Geek Gadgets 1/ADE-1.bin/ade-dist/gnat-2.06-src.tgz/tar.out/fsf/gnat/ada/sinfo.ads

Text File | 1996-09-28 | 269KB | 7,199 lines

------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                                S I N F O                                 --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--                            $Revision: 1.254 $                            --
--                                                                          --
--        Copyright (c) 1992,1993,1994,1995 NYU, All Rights Reserved        --
--                                                                          --
-- The GNAT library is free software; you can redistribute it and/or modify --
-- it under terms of the GNU Library General Public License as published by --
-- the Free Software  Foundation; either version 2, or (at your option) any --
-- later version.  The GNAT library is distributed in the hope that it will --
-- be useful, but WITHOUT ANY WARRANTY;  without even  the implied warranty --
-- of MERCHANTABILITY  or  FITNESS FOR  A PARTICULAR PURPOSE.  See the  GNU --
-- Library  General  Public  License for  more  details.  You  should  have --
-- received  a copy of the GNU  Library  General Public License  along with --
-- the GNAT library;  see the file  COPYING.LIB.  If not, write to the Free --
-- Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.        --
--                                                                          --
------------------------------------------------------------------------------

--  This package defines the structure of the abstract syntax tree. The Tree
--  package provides a basic tree structure. Sinfo describes how this
--  structure is used to represent the syntax of an Ada program.

--  Note: the grammar used here is taken from Version 5.95 of the RM, dated
--  November 1994. The grammar in the RM is followed very closely in the tree
--  design, and is repeated as part of this source file.

--  The tree contains not only the full syntactic representation of the
--  program, but also the results of semantic analysis. In particular, the
--  nodes for defining identifiers, defining character literals and defining
--  operator symbols, collectively referred to as entities, represent what
--  would normally be regarded as the symbol table information. In addition
--  a number of the tree nodes contain semantic information.

--  WARNING: There is a C version of this package. Any changes to this
--  source file must be properly reflected in this C header file sinfo.h
--  which is created automatically from sinfo.ads using xsinfo.spt.

with Types;  use Types;
with Uintp;  use Uintp;
with Urealp; use Urealp;

package Sinfo is

   ---------------------------------
   -- Making Changes to This File --
   ---------------------------------

   --  If changes are made to this file, a number of related steps must be
   --  carried out to ensure consistency. First, if a field access function
   --  is added, it appears in six places:

   --    The documentation associated with the node
   --    The spec of the access function in sinfo.ads
   --    The body of the access function in sinfo.adb
   --    The spec of the set procedure in sinfo.ads
   --    The body of the set procedure in sinfo.adb
   --    The pragma Inline at the end of sinfo.ads

   --  The field chosen must be consistent in all places, and, for a node
   --  that is a subexpression, must not overlap any of the standard
   --  expression fields. In the body, the calls to the Dcheck_Node debug
   --  procedure will need cross-references adding in alphabetical order.

   --  In addition, if any of the standard expression fields is changed, then
   --  the utiliy program which creates the Treeprs spec (in file treeprs.ads)
   --  must be updated appropriately, since it special cases expression fields.

   --  If a new tree node is added, then the following changes are made

   --    Add it to the documentation in the appropriate place
   --    Add its fields to this documentation section
   --    Define it in the appropriate classification in Node_Kind
   --    In the body (sinfo), add entries to the Dcheck calls for all
   --     its fields (except standard expression fields) to include
   --     the new node in the debug cross-reference list
   --    Add an appropriate section to the case statement in sprint.adb
   --    Add an appropriate section to the case statement in sem.adb
   --    For a subexpression, add an appropriate sections to the case
   --     statement in sem_eval.adb
   --    For a subexpression, add an appropriate sections to the case
   --     statement in sem_res.adb

   --  Finally, four utility programs must be run:

   --    Run csinfo.spt to check that you have made the changes consistently.
   --     It checks most of the rules given above, with clear error messages.
   --     This utility reads sinfo.ads and sinfo.adb and generates a report
   --     to standard output.

   --    Run xsinfo.spt to create a-sinfo.h, the corresponding C header. This
   --     utility reads sinfo.ads and generates a-sinfo.h. Note that it
   --     does not need to read sinfo.adb, since the contents of the body
   --     are algorithmically determinable from the spec.

   --    Run xtreeprs.spt to create treeprs.ads, an updated version of
   --     the module that is used to drive the tree print routine. This
   --     utility reads (but does not modify) treeprs.adt, the template
   --     that provides the basic structure of the file, and then fills in
   --     the data from the comments in sinfo.ads.

   --    Run xnmake.spt to create nmake.ads and nmake.adb, the package body
   --     and spec of the Nmake package which contains functions for
   --     constructing nodes.

   --  Note: sometime we could write a utility that actually generated the
   --  body of sinfo from the spec instead of simply checking it, since, as
   --  noted above, the contents of the body can be determined from the spec.

   --------------------------------
   -- Implicit Nodes in the Tree --
   --------------------------------

   --  Generally the structure of the tree very closely follows the grammar
   --  as defined in the RM. However, certain nodes are omitted to save
   --  space and simplify semantic processing. Two general classes of such
   --  omitted nodes are as follows:

   --   If the only possibilities for a non-terminal are one or more other
   --   non terminals (i.e. the rule is a "skinny" rule), then usually the
   --   corresponding node is omitted from the tree, and the target construct
   --   appears directly. For example, a real type definition is either a
   --   floating point definition or a fixed point definition. No explicit
   --   node appears for real type definition. Instead either the floating
   --   point definition or fixed point definition appears directly.

   --   If a non-terminal corresponds to a list of some other non-terminal
   --   (possibly with separating punctuation), then usually it is omitted
   --   from the tree, and a list of components appears instead. For
   --   example, sequence of statements does not appear explicitly in the
   --   tree. Instead a list of statements appears directly.

   --  Some additional cases of omitted nodes occur and are documented
   --  individually. In particular, many nodes are omitted in the tree
   --  generated for an expression.

   -------------------------------------------
   -- Handling of Defining Identifier Lists --
   -------------------------------------------

   --  In several declarative forms in the syntax, lists of defining
   --  identifiers appear (object declarations, component declarations,
   --  number declarations etc.)

   --  The semantics of such statements are equivalent to a series of
   --  identical declarations of single defining identifiers (except that
   --  conformance checks require the same grouping of identifiers in the
   --  parameter case).

   --  To simplify semantic processing, the parser breaks down such multiple
   --  declaration cases into sequences of single declarations, duplicating
   --  type and initialization information as required. The flags More_Ids
   --  and Prev_Ids are used to record the original form of the source in
   --  the case where the original source used a list of names, More_Ids
   --  being set on all but the last name and Prev_Ids being set on all
   --  but the first name. These flags are used to reconstruct the original
   --  source (e.g. in the Sprint package), and also are included in the
   --  conformance checks, but otherwise have no semantic significance.

   --  Note: the reason that we use More_Ids and Prev_Ids rather than
   --  First_Name and Last_Name flags is so that the flags are off in the
   --  normal one identifier case, which minimizes tree print output.

   -----------------------
   -- Use of Node Lists --
   -----------------------

   --  With a few exceptions, if a construction of the form {non-terminal}
   --  appears in the tree, lists are used in the corresponding tree node
   --  (see package Mlists for handling of node lists). In this case a field
   --  of the parent node points to a list of nodes for the non-terminal. The
   --  field name for such fields has a plural name which always ends in "s".
   --  For example, a case statement has a field Alternatives pointing to a
   --  list of case statement alternative nodes.

   --  Only fields pointing to lists have names ending in "s", so generally
   --  the structure is strongly typed, fields not ending in s point to
   --  single nodes, and fields ending in s point to lists.

   --  The following example shows how a traversal of a list is written. We
   --  suppose here that Stmt points to a N_Case_Statement node which has
   --  a list field called Alternatives:

   --   Alt := First (Alternatives (Stmt));
   --   while Present (Alt) loop
   --      ..
   --      -- processing for case statement alternative Alt
   --      ..
   --      Alt := Next (Alt);
   --   end loop;

   --  The Present function tests for Empty, which in this case signals the
   --  end of the list. First returns Empty immediately if the list is empty.
   --  Present is defined in Atree, First and Next are defined in Nlists.

   --  The exceptions to this rule occur with {DEFINING_IDENTIFIERS} in all
   --  contexts, which is handled as described in the previous section, and
   --  with {,library_unit_NAME} in the N_With_Clause mode, which is handled
   --  using the First_Name and Last_Name flags, as further detailed in the
   --  description of the N_With_Clause node.

   ---------------------
   -- Optional Fields --
   ---------------------

   --  Fields which correspond to a section of the syntax enclosed in square
   --  brackets are generally omitted (and the corresponding field set to
   --  Empty for a node, or No_List for a list). The documentation of such
   --  fields notes these cases. One exception to this rule occurs in the
   --  case of possibly empty statement sequences (such as the sequence of
   --  statements in an entry call alternative). Such cases appear in the
   --  syntax rules as [SEQUENCE_OF_STATEMENTS] and the fields corresponding
   --  to such optional statement sequences always contain an empty list (not
   --  No_List) if no statements are present.

   --  Note: the utility program that constructs the body and spec of the
   --  Nmake package relies on the format of the comments to determine if
   --  a field should have a default value in the corresponding make routine.
   --  The rule is that if the first line of the description of the field
   --  contains the string "(set to xxx if", then a default value of xxx is
   --  provided for this field in the corresponding Make_yyy routine.

   -----------------------------------
   -- Note on Body/Spec Terminology --
   -----------------------------------

   --  In informal discussions about Ada, it is customary to refer to package
   --  and subprogram specs and bodies. However, this is not technically
   --  correct, what is normally referred to as a spec or specification is in
   --  fact a package declaration or subprogram declaration. We are careful
   --  in GNAT to use the correct terminology and in particular, the full
   --  word specification is never used as an incorrect substitute for
   --  declaration. The structure and terminology used in the tree also
   --  reflects the grammar and thus uses declaration and specification in
   --  the technically correct manner.

   --  However, there are contexts in which the informal terminology is
   --  useful. We have the word "body" to refer to the Interp_Etype declared by
   --  the declaration of a unit body, and in some contexts we need a
   --  similar term to refer to the entity declared by the package or
   --  subprogram declaration, and simply using declaration can be confusing
   --  since the body also has a declaration.

   --  An example of such a context is the link between the package body
   --  and its declaration. With_Declaration is confusing, since
   --  the package body itself is a declaration.

   --  To deal with this problem, we reserve the informal term Spec, i.e.
   --  the popular abbreviation used in this context, to refer to the entity
   --  declared by the package or subprogram declaration. So in the above
   --  example case, the field in the body is called With_Spec.

   --  Another important context for the use of the word Spec is in error
   --  messages, where a hyper-correct use of declaration would be confusing
   --  to a typical Ada programmer, and even for an expert programmer can
   --  cause confusion since the body has a declaration as well.

   --  So, to summarize:

   --     Declaration    always refers to the syntactic entity that is called
   --                    a declaration. In particular, subprogram declaration
   --                    and package declaration are used to describe the
   --                    syntactic entity that includes the semicolon.

   --     Specification  always refers to the syntactic entity that is called
   --                    a specification. In particular, the terms procedure
   --                    specification, function specification, package
   --                    specification, subprogram specification always refer
   --                    to the syntactic entity that has no semicolon.

   --     Spec           is an informal term, used to refer to the entity
   --                    that is declared by a task declaration, protected
   --                    declaration, generic declaration, subprogram
   --                    declaration or package declaration.

   --  This convention is followed throughout the GNAT documentation
   --  both internal and external, and in all error message text.

   ------------------------
   -- Internal Use Nodes --
   ------------------------

   --  These are Node_Kind settings used in the internal implementation
   --  which are not logically part of the specification.

   --  N_Unused_At_Start
   --  Completely unused entry at the start of the enumeration type. This
   --  is inserted so that no legitimate value is zero, which helps to get
   --  better debugging behavior, since zero is a likely uninitialized value).

   --  N_Unused_At_End
   --  Completely unused entry at the end of the enumeration type. This is
   --  handy so that arrays with Node_Kind as the index type have an extra
   --  entry at the end (see for example the use of the Pchar_Pos_Array in
   --  Treepr, where the extra entry provides the limit value when dealing
   --  with the last used entry in the array).

   ---------------------
   -- Syntactic Nodes --
   ---------------------

   --  In the following node definitions, all fields, both syntactic and
   --  semantic, are documented. The one exception is in the case of entities
   --  (defining indentifiers, character literals and operator symbols),
   --  where the usage of the fields depends on the entity kind. Entity
   --  fields are fully documented in the separate package Einfo.

   --  In the node definitions, three common sets of fields are abbreviated
   --  to save both space in the documentation, and also space in the string
   --  (defined in Tree_Print_Strings) used to print trees. The following
   --  abbreviations are used:

   --  Note: the utility program that creates the Treeprs spec (in the file
   --  treeprs.ads) knows about the special fields here, so it must be
   --  modified if any change is made to these fields.

   --    "plus fields for binary operator"
   --       Chars                   (Name1)      Name_Id for the operator
   --       Left_Opnd               (Node2)      left operand expression
   --       Right_Opnd              (Node3)      right operand expression
   --       Entity                  (Node4-Sem)  defining entity for operator
   --       Do_Overflow_Check       (Flag17-Sem) set if overflow check needed
   --       Has_Private_View        (Flag11-Sem) set in generic units.

   --    "plus fields for unary operator"
   --       Chars                   (Name1)      Name_Id for the operator
   --       Right_Opnd              (Node3)      right operand expression
   --       Entity                  (Node4-Sem)  defining entity for operator
   --       Do_Overflow_Check       (Flag17-Sem) set if overflow check needed
   --       Has_Private_View        (Flag11-Sem) set in generic units.

   --    "plus fields for expression"
   --       Paren_Count                          number of parentheses levels
   --       Etype                   (Node5-Sem)  type of the expression
   --       Assignment_OK           (Flag1-Sem)  set if modification is OK
   --       Is_Overloaded           (Flag5-Sem)  >1 type interpretation exists
   --       Is_Static_Expression    (Flag6-Sem)  set for static expression
   --       Raises_Constraint_Error (Flag7-Sem)  evaluation raises CE
   --       Has_No_Side_Effects     (Flag8-Sem)  set if known to be SE free
   --       Do_Range_Check          (Flag9-Sem)  set if a range check needed
   --       Is_Controlling_Actual   (Flag16-Sem) set for controlling argument
   --       Cannot_Be_Constant      (Flag18-Sem) set if constant not possible

   --  Note: see under (EXPRESSION) for further details on the use of
   --  the Paren_Count field to record the number of parentheses levels.

   --  Node_Kind is the type used in the Nkind field to indicate the node
   --  kind. The actual definition of this type is given later (the reason
   --  for this is that we want the descriptions ordered by logical chapter
   --  in the RM, but the type definition is reordered to facilitate the
   --  definition of some subtype ranges. The individual descriptions of
   --  the nodes show how the various fields are used in each node kind,
   --  as well as providing logical names for the fields. Functions and
   --  procedures are provided for accessing and setting these fields
   --  using these logical names.

   -----------------------
   -- Gigi Restrictions --
   -----------------------

   --  The tree passed to Gigi is more restricted than the general tree form.
   --  For example, as a result of expansion, most of the tasking nodes can
   --  never appear. For each node to which either a complete or partial
   --  restriction applies, a note entitled "Gigi restriction" appears which
   --  documents the restriction.

   --  Note that most of these restrictions apply only to trees generated when
   --  code is being generated, since they involved expander actions that
   --  destroy the tree.

   --  The list of notes is by no means complete ???

   ------------------------
   -- Common Flag Fields --
   ------------------------

   --  The following flag fields appear in all nodes

   --  Analyzed (Flag15-Sem)
   --    This flag is used to indicate that a node (and all its children
   --    have been analyzed. It is used to avoid reanalysis of a node that
   --    has already been analyzed, both for efficiency and functional
   --    correctness reasons.

   --  Error_Posted (Flag13)
   --    This flag is used to avoid multiple error messages being posted
   --    on or referring to the same node. This flag is set if an error
   --    message refers to a node or is posted on its source location,
   --    and has the effect of inhibiting further messages involving
   --    this same node.

   --  Comes_From_Source
   --    This flag is on for any nodes built by the scanner or parser from
   --    the source program, and off for any nodes built by the analyzer or
   --    expander. It indicates that a node comes from the original source.
   --    This flag is defined in Atree.

   ------------------------------------
   -- Description of Semantic Fields --
   ------------------------------------

   --  The meaning of the syntactic fields is generally clear from their
   --  names without any further description, since the names are chosen
   --  to correspond very closely to the syntax in the reference manual.
   --  This section describes the usage of the semantic fields, which are
   --  used to contain additional information determined during semantic
   --  analysis.

   --  Actions (List1-Sem)
   --    Present in an N_Expression_Actions node, to contain the list of
   --    associated actions, and in an N_Freeze_Entity node where it
   --    holds the list of associated freezing actions.

   --  Activation_Chain_Entity (Node2-Sem)
   --    This is used in tree nodes representing task activators (blocks,
   --    subprogram bodies, package declarations, and task bodies). It is
   --    initially Empty, and then gets set to point to the entity for the
   --    declared Activation_Chain variable when the first task is declared.
   --    When tasks are declared in the corresponding declarative region
   --    this entity is located by name (its name is always _Chain) and
   --    the declared tasks are added to the chain.

   --  Acts_As_Spec (Flag4-Sem)
   --    A flag set in the N_Subprogram_Body node for a subprogram body
   --    which is acting as its own spec. This flag also appears in the
   --    compilation unit node at the library level for such a subprogram
   --    (see further description in spec of Lib package).

   --  Aggregate_Bounds (Node3-Sem)
   --    Present in N_Aggregate nodes. Points to an N_Range node that is used
   --    to hold the bounds of the aggregate. We don't need a full blown itype
   --    for the bounds of internal aggregates, since this type would never be
   --    used other than to reference the bounds in any case. This field is
   --    used only when the N_Aggregate node is for a nested array aggregate.
   --    Note that in any case a subaggregate has no type in the official RM
   --    semantics, so it is quite appropriate not to build a full Itype for
   --    a subaggregate. See Sem_Aggr for further details.

   --  Assignment_OK (Flag1-Sem)
   --     This flag is set in a subexpression node corresponding to indicate
   --     that the associated object can be modified, even if this would not
   --     normally be permissible (either by direct assignment, or by being
   --     passed as an out or in-out parameter. This is used by the expander
   --     for a number of purposes, including initialzation of constants and
   --     limited type objects (such as tasks), setting discriminant fields,
   --     setting tag values, etc.

   --  Backwards_OK (Flag5-Sem)
   --     A flag present in the N_Assignment_Statement node. It is used only
   --     if the type being assigned is an array type, and is set if analysis
   --     determines that it is definitely safe to do the copy backwards, i.e.
   --     starting at the highest addressed element. Note that if neither of
   --     the flags Forwards_OK or Backwards_OK is set, it means that the
   --     front end could not determine that either direction is definitely
   --     safe, and a runtime check is required.

   --  Body_Required (Flag3-Sem)
   --     A flag that appears in the N_Compilation_Unit node for a package
   --     spec to indicate that a body is required. In Ada 95, if this flag
   --     is not set, then a body may not be present. In Ada 83, if this flag
   --     is not set, then a body is optional.

   --  Cannot_Be_Constant (Flag18-Sem)
   --     Besides expressions that are static by Ada 95, rules, Gigi treats
   --     some additional expressions as constants (an example would be
   --     X.C'First_Bit, which is not static, but which may often be known
   --     to be a compile time constant by Gigi. In order to test whether
   --     an non-static expression is static in this sense, Gigi evaluates
   --     the expression. This causes trouble if the expression contains any
   --     attached implicit types, or any expression actions nodes. This flag
   --     is set on all expression nodes with implicit types and expression
   --     action nodes, and on all their ancestor expressions. It is used by
   --     Gigi to avoid the troublesome evaluation attempts.

   --  Cleanup_Call (Node5-Sem)
   --     This is optionally present in a handled statement sequence node.
   --     It represents the call to be made to a cleanup procedure on scope
   --     exit (either normal or abnormal). This is a N_Procedure_Call node
   --     where the name of the procedure is a simple identifier, and so are
   --     all the parameters.

   --  Controlling_Argument (Node1-Sem)
   --     This field is set in procedure and function call nodes if the call
   --     is a dispatching call (it is Empty for a non-dispatching call).
   --     It indicates the source of the controlling tag for the call. For
   --     Procedure calls, the Controlling_Argument is one of the actuals.
   --     For a function that has a dispatching result, it is an entity in
   --     the context of the call that can provide a tag, or else it is the
   --     tag of the root type of the class.

   --  Conversion_OK (Flag14-Sem)
   --     A flag set on type conversion nodes to indicate that the conversion
   --     is to be considered as being valid, even though it is the case that
   --     the conversion is not valid Ada. This is used for the Enum_Rep,
   --     Fixed_Value and Integer_Value attributes, for internal conversions
   --     done for fixed-point operations, and for certain conversions for
   --     calls to initialization procedures. If Conversion_OK is set, then
   --     Etype must be set (the analyzer assumes that Etype has been set).
   --     For the case of fixed-point operands, it also indicates that the
   --     conversion is to be a direct conversion of the underlying integer
   --     result, with no regard to the small operand.

   --  Corresponding_Body (Node5-Sem)
   --     This field is set in subprogram declarations, where it is needed
   --     if a pragma Inline is present and the subprogram is called, in
   --     generic declarations if the generic is instantiated, and also in
   --     package declarations that contain inlined subprograms that are
   --     called, or generic declarations that are instantiated. It points
   --     to the defining entity for the corresponding body.

   --  Corresponding_Integer_Value (Uint4-Sem)
   --     This field is set in real literals of fixed-point types (it is not
   --     used for floating-point types). It contains the integer value used
   --     to represent the fixed-point value. It is also set on the universal
   --     real literals used to represent bounds of fixed-point base types
   --     and their first named subtypes.

   --  Corresponding_Spec (Node5-Sem)
   --     This field is set in subprogram, package, task, and protected body
   --     nodes, where it points to the defining entity in the corresponding
   --     spec. The attribute is also set in N_With_Clause nodes, where
   --     it points to the defining entity for the with'ed spec, and in
   --     a subprogram naming declaration when it is a Renaming_As_Body.
   --     The field is Empty if there is no corresponding spec, as in the
   --     case of a subprogram body that serves as its own spec.

   --  Corresponding_Stub (Node3-Sem)
   --    This field is present in an N_Subunit node. It holds the node in
   --    the parent unit that is the stub declaration for the subunit. it is
   --    set when analysis of the stub forces loading of the proper body. If
   --    expansion of the proper body creates new declarative nodes, they are
   --    inserted at the point of the corresponding_stub.

   --  Debug_Statement (Node3-Sem)
   --    This field is present in an N_Pragma node. It is used only for
   --    a Debug pragma or pragma Assert with a second parameter. The
   --    parameter is of the form of an expression, as required by the
   --    pragma syntax, but is actually a procedure call. To simplify
   --    semantic processing, the parser creates a copy of the argument
   --    rearranged into a procedure call statement and places it in the
   --    Debug_Statement field.

   --  Do_Access_Check (Flag11-Sem)
   --     This flag is set on N_Explicit_Dereference, N_Indexed_Component or
   --     N_Selected_Component nodes to indicate that the Prefix field of
   --     the node points to a pointer whose value must be checked for null
   --     before carrying out the operation. The actual check is dealt with
   --     by Gigi (all the front end does is to set the flag).

   --  Do_Accessibility_Check (Flag3-Sem)
   --     This flag is set on N_Parameter_Specification nodesto indicate that
   --     that an accessibility check is required for the parameter. It is
   --     not yet decided who takes care of this check (TBD).

   --  Do_Discriminant_Check (Flag3-Sem)
   --     This flag is set on N_Selected_Component nodes to indicate that a
   --     discriminant check is required using the discriminant check routine
   --     associated with the selector. The actual check is dealt with by
   --     Gigi (all the front end does is to set the flag).

   --  Do_Division_Check (Flag3-Sem)
   --     This flag is set on a division operator (/ mod rem) to indicate
   --     that a zero divide check is required. The actual check is dealt
   --     with by the backend (all the front end does is to set the flag).

   --  Do_Length_Check (Flag4-Sem)
   --     This flag is set in an N_Assignment_Statement, N_Op_And, N_Op_Or,
   --     N_Op_Xor, or N_Type_Conversion node to indicate that a length check
   --     is required. It is not determined who deals with this flag (TBD).

   --  Do_Overflow_Check (Flag17-Sem)
   --     This flag is set on an operator where an overflow check is required
   --     on the operation. The actual check is dealt with by the backend
   --     (all the front end does is to set the flag). The other cases where
   --     this flag is used is on a Type_Conversion node and for attribute
   --     reference nodes. For a type conversion, it means that the conversion
   --     is from one base type to another, and the value may not fit in the
   --     target base type. See also the description of Do_Range_Check for
   --     this case. The only attribute references which use this flag are
   --     Pred and Succ, where it means that the result should be checked
   --     for going outside the base range.

   --  Do_Range_Check (Flag9-Sem)
   --     This flag is set on an expression which appears in a context where
   --     a range check is required. The target type is clear from the
   --     context. The contexts in which this flag can appear are limited to
   --     the following.

   --       Right side of an assignment. In this case the target type is
   --       taken from the left side of the assignment, which is referenced
   --       by the Name of the N_Assignment_Statement node.

   --       Subscript expressions in an indexed component. In this case the
   --       target type is determined from the type of the array, which is
   --       referenced by the Prefix of the N_Indexed_Component node.

   --       Parameter expression for an IN parameter, appearing either
   --       directly in the Parameter_Associations list of a call or as
   --       the Expression of an N_Parameter_Association node that appears
   --       in this list. In either case, the check is against the type of
   --       the formal. Note that OUT and IN OUT parameters are handled by
   --       expanding assignments and explicit type conversions where a
   --       range check is required.

   --       Initialization expression for the initial value in an object
   --       declaration. In this case the Do_Range_Check flag is set on
   --       the initialization expression, and the check is against the
   --       range of the type of the object being declared.

   --       The expression of a type conversion. In this case the range check
   --       is against the target type of the conversion. See also the use of
   --       Do_Overflow_Check on a type conversion. The distinction is that
   --       the ovrflow check protects against a value that is outside the
   --       range of the target base type, whereas a range check checks that
   --       the resulting value (which is a value of the base type of the
   --       target type), satisfies the range constraint of the target type.

   --     Note: when a range check is required in contexts other than those
   --     listed above (e.g. in a return statement), an additional type
   --     conversion node is introduced to represent the required check.

   --  Do_Storage_Check (Flag17-Sem)
   --     This flag is set in an N_Allocator node to indicate that a storage
   --     check is required for the allocation, or in an N_Subprogram_Body
   --     node to indicate that a stack check is required in the subprogram
   --     prolog. The N_Allocator case is handled by the routine that expands
   --     the call to the runtime routine. The N_Subprogram_Body case is
   --     handled by the backend, and all the semantics does is set the flag.

   --  Do_Tag_Check (Flag3-Sem)
   --     This flag is set on an N_Assignment_Statement, N_Function_Call,
   --     N_Procedure_Call_Statement, N_Type_Conversion or N_Return_Statememt
   --     node to indicate that the tag check can be suppressed. It is not
   --     yet decided how this flag is used (TBD).

   --  Elaborate_Present (Flag4-Sem)
   --     This flag is set in the N_With_Clause node to indicate that a
   --     pragma Elaborate pragma appears for the with'ed units.

   --  Elaborate_All_Present (Flag1-Sem)
   --     This flag is set in the N_With_Clause node to indicate that a
   --     pragma Elaborate_All pragma appears for the with'ed units.

   --  Elaborate_Body_Present (Flag7-Sem)
   --     This flag is set in the N_Compilation_Unit node to indicate that
   --     a valid Elaborate_Body pragma appears for this unit.

   --  Enclosing_Variant (Node2-Sem)
   --     This field is present in the N_Variant node and identifies the
   --     Node_Id corresponding to the immediately enclosing variant when
   --     the variant is nested, and N_Empty otherwise. Set during semantic
   --     processing of the variant part of a record type.

   --  Entity (Node4-Sem)
   --     Appears in all direct names (identifier, character literal,
   --     operator symbol), as well as expanded names, and attributes that
   --     denote entities, such as 'Class. Points to the entity for the
   --     corresponding defining occurrence. Set after name resolution.
   --     In the case of identifiers in a WITH list, the corresponding
   --     defining occurrence is in a separately compiled file, and this
   --     pointer must be set using the library Load procedure. Note that
   --     during name resolution, the value in Entity may be temporarily
   --     incorrect (e.g. during overload resolution, Entity is
   --     initially set to the first possible correct interpretation, and
   --     then later modified if necessary to contain the correct value
   --     after resolution).

   --  Etype (Node5-Sem)
   --     Appears in all expression nodes, all direct names, and all
   --     entities. Points to the entity for the related type. Set after
   --     type resolution. Normally this is the actual subtype of the
   --     expression. However, in certain contexts such as the right side
   --     of an assignment, subscripts, arguments to calls, returned value
   --     in a function, initial value etc. it is the desired target type.
   --     In the event that this is different from the actual type, the
   --     Do_Range_Check flag will be set if a range check is required.
   --     During semantic analysis, this is used to point to a list of
   --     N_Interpretation nodes to represent possible interpretations
   --     resulting from overloading, see Sem_Type for further details.

   --  First_Inlined_Subprogram (Node5-Sem)
   --     Present in the N_Compilation_Unit node for the main program. Points
   --     to a chain of entities for subprograms that are to be inlined. The
   --     Next_Inlined_Subprogram field of these entities is used as a link
   --     pointer with Empty marking the end of the list. This field is Empty
   --     if there are no inlined subprograms or inlining is not active.

   --  First_Itype (Node2-Sem)
   --     Points to first of a list of entities for implicit types associated
   --     with a node. Set to Empty if there are no associated implicit types.
   --     See package Itypes for further details.

   --  First_Named_Actual (Node4-Sem)
   --     Present in procedure call statement and function call nodes, and
   --     also in Intrinsic nodes. Set during semantic analysis to point to
   --     the first named parameter where parameters are ordered by declaration
   --     order (as opposed to the actual order in the call which may be
   --     different due to named associations). Note: this field points to the
   --     explicit actual parameter itself, not the N_Parameter_Association
   --     node (its parent).

   --  First_Real_Statement (Node2-Sem)
   --     Present in N_Handled_Sequence_Of_Statements node. Normally set to
   --     Empty. Used only when declarations are moved into the statement
   --     part of a construct as a result of wrapping an AT END handler that
   --     is required to cover the declarations. In this case, this field is
   --     used to remember the location in the statements list of the first
   --     real statement, i.e. the statement that used to be first in the
   --     statement list before the declarations were prepended.

   --  First_Subtype_Link (Node5-Sem)
   --     Present in N_Freeze_Entity node for an anonymous base type that
   --     is implicitly created by the declaration of a first subtype. It
   --     points to the entity for the first subtype.

   --  Float_Truncate (Flag11-Sem)
   --     A flag present in type conversion nodes. This is used for float
   --     to integer conversions where truncation is required rather than
   --     rounding. Note that Gigi does not handle type conversions from real
   --     to integer with rounding (see Expand_N_Type_Conversion).

   --  Forwards_OK (Flag5-Sem)
   --     A flag present in the N_Assignment_Statement node. It is used only
   --     if the type being assigned is an array type, and is set if analysis
   --     determines that it is definitely safe to do the copy forwards, i.e.
   --     starting at the lowest addressed element. Note that if neither of
   --     the flags Forwards_OK or Backwards_OK is set, it means that the
   --     front end could not determine that either direction is definitely
   --     safe, and a runtime check is required.

   --  Generic_Parent (Node5-Sem)
   --     Generic_parent is defined on declaration nodes that are instances.
   --     The value of Generic_Parent is the generic entity from which the
   --     instance is obtained.

   --  Has_Dynamic_Itype (Flag14-Sem)
   --     Flag set if the node has a non-Empty Itypes list, and at least one
   --     of the Itypes in the list is dynamic. A dynamic Itype is a type that
   --     has either a range constraint or a discriminant constraint involving
   --     a dynamic expression. A dynamic expression is a non-static expression
   --     that is not the name of an enclosing discriminant. Operationally,
   --     dynamic Itypes are those that require runtime elaboration.

   --  Has_No_Elab_Code (Flag17-Sem)
   --     A flag that appears in the N_Compilation_Unit node to indicate
   --     whether or not elaboration code is present for this unit. It is
   --     initially set true for subprogram specs and bodies and false for
   --     package specs and bodies. Gigi may set the flag in the package
   --     case if it determines that no elaboration code is generated. Note
   --     that this flag is not related to the Is_Preelaborated status, there
   --     can be preelaborated packages that generate elaboration code, and
   --     non-preelaborated packages which do not generate elaboration code.

   --  Has_No_Side_Effects (Flag8-Sem)
   --     A flag present in all expression nodes. Set by semantic analysis
   --     after determining that a given subexpression has no side effects.

   --  Has_Priority_Pragma (Flag6-Sem)
   --     A flag present in N_Subprogram_Body, N_Task_Definition and
   --     N_Protected_Definition nodes to flag the presence of either
   --     a Priority or Interrupt_Priority pragma in the declaration
   --     sequence (public or private in the task and protected cases)

   --  Has_Private_View (Flag11-Sem)
   --     A flag present in generic nodes that have an entity, to indicate
   --     that the node has a private type. Used to exchange private
   --     and full declarations if the visibility at instantiation is
   --     different from the visibility at generic definition.

   --  Has_Storage_Size_Pragma (Flag5-Sem)
   --     A flag present in an N_Task_Definition node to flag the presence
   --     of a Storage_Size pragma

   --  Homonym (Node4-Sem)
   --     Present in defining identifiers, defining character literals and
   --     defining operator symbols (i.e. in all entities). Within a given
   --     scope, homonyms are chained using this field. See Einfo for details.

   --  Implicit_With (Flag17-Sem)
   --     This flag is set in the N_With_Clause node that is implicitly
   --     generated for runtime units that are loaded by the expander, and
   --     also for package System, if it is loaded implicitly by a use of
   --     the 'Address or 'Tag attribute

   --  Is_Controlling_Argument (Flag16-Sem)
   --     This flag is set on in an expression that is a controlling argument
   --     in a dispatching call. It is off in all other cases. See Sem_Disp
   --     for details of its use.

   --  Is_Current_Instance (Flag14-Sem)
   --     This flag is set on identifiers that denote the current type
   --     declaration (RM 8.6), that is to say that appear legally within
   --     the declaration itself (record or task).

   --  Is_Overloaded (Flag5-Sem)
   --     A flag present in all expression nodes. Used temporarily during
   --     overloading determination. The setting of this flag is not
   --     relevant once overloading analysis is complete.

   --  Is_Static_Expression (Flag6-Sem)
   --     Indicates that an expression is a static expression (RM 4.9). See
   --     spec of package Sem_Eval for full details on the use of this flag.

   --  Is_Task_Master (Flag5-Sem)
   --     A flag set in a Subprogram_Body, Block_Statement or Task_Body node
   --     to indicate that the construct is a task master (i.e. has declared
   --     tasks or declares an access to a task type).

   --  Library_Unit (Node4-Sem)
   --    In a stub node, the Library_Unit field points to the compilation unit
   --    node of the corresponding subunit.
   --
   --    In a with clause node, the Library_Unit field points to the spec
   --    of the with'ed unit.
   --
   --    In a compilation unit node, the use of this field depends on
   --    the unit type:
   --
   --      For a subprogram body, the Library_Unit field points to the
   --      compilation unit node of the corresponding spec, unless
   --      Acts_As_Spec is set, in which case it points to itself.
   --
   --      For a package body, the Library_Unit field points to the
   --      compilation unit node of the corresponding spec.
   --
   --      For a subprogram spec to which pragma Inline applies, the
   --      Library_Unit field points to the compilation unit node of
   --      the corresponding body, if inlining is active.
   --
   --      For a generic declaration, the Library_Unit field points
   --      to the compilation unit node of the corresponding generic body.
   --
   --      For a subunit, the Library_Unit field points to the compilation
   --      unit node of the parent body.
   --
   --    Note that this field is not used to hold the parent pointer for a
   --    child unit (which might in any case need to use it for some other
   --    purpose as described above). Instead for a child unit, implicit
   --    with's are generated for all parents.

   --  Next_Entity (Node2-Sem)
   --     Present in defining identifiers, defining character literals and
   --     defining operator symbols (i.e. in all entities). The entities of
   --     a scope are chained, and this field is used as the forward pointer
   --     for this list. See Einfo for further details.

   --  Next_Interp (Node2-Sem)
   --     Used to chain entries in the N_Interpretation node list used to
   --     store multiple overloaded interpretations of a single node.

   --  Next_Named_Actual (Node4-Sem)
   --     Present in parameter association node. Set during semantic
   --     analysis to point to the next named parameter, where parameters
   --     are ordered by declaration order (as opposed to the actual order
   --     in the call, which may be different due to named associations).
   --     Not that this field points to the explicit actual parameter itself,
   --     not to the N_Parameter_Association node (its parent).

   --  Next_Use_Clause (Node3-Sem)
   --     While use clauses are active during semantic processing, they
   --     are chained from the scope stack entry, using Next_Use_Clause
   --     as a link pointer, with Empty marking the end of the list. The
   --     head pointer is in the scope stack entry (First_Use_Clause). At
   --     the end of semantic processing (i.e. when Gigi sees the tree,
   --     the contents of this field is undefined and should not be read).

   --  No_Default_Init (Flag7-Sem)
   --     Present in N_Object_Declaration to indicate that the object must
   --     not be initialized (by Initialize or a call to _init_proc). This
   --     is needed for controlled aggregates.

   --  No_Defer (Flag1-Sem)
   --     Present in N_Raise_Statement node. Normally a raise statement makes
   --     a call to defer task abortion. If this flag is set, this defer call
   --     is suppressed (this is used to deal with the raise Program_Error
   --     statements that appear in System.Finalization_Implementation).

   --  Object_Definition_Itypes (Node5-Sem)
   --     Used to store Itypes coming from the Object_Definition of an object
   --     declaration. These must be kept separate from the Itypes for the
   --     declaration itself. See processing in Sem_Ch3 for further details.

   --  Others_Discrete_Choices (List1-Sem)
   --     When a case statement or variant is analyzed, the semantic checks
   --     determine the actual list of choices that correspond to an others
   --     choice. This list is materialized for later use by the expander
   --     and the Others_Discrete_Choices field of an N_Others_Choice node
   --     points to this materialized list of choices, which is in standard
   --     format for a list of discrete choices, except that of course it
   --     cannot contain an N_Others_Choice entry.

   --  Parent_Spec (Node4-Sem)
   --     For a library unit that is a child unit spec (package or subprogram
   --     declaration, generic declaration or instantiation, or library level
   --     rename, this field points to the compilation unit node for the parent
   --     package specification. This field is Empty for library bodies (the
   --     parent spec in this case can be found from the corresponding spec).

   --  Procedure_To_Call (Node4-Sem)
   --     Present in N_Allocator. N_Free_Statement, and N_Return_Statement
   --     nodes. References the entity for the declaration of the procedure
   --     to be called to accomplish the required operation (i.e. for the
   --     Allocate procedure in the case of N_Allocator and N_Return_Statement
   --     (for allocating the return value), and for the Deallocate procedure
   --     in the case of N_Free_Statement.

   --  Raises_Constraint_Error (Flag7-Sem)
   --     Set on a potentially static subexpression that will raise a
   --     constraint error exception if it is evaluated (e.g. because
   --     of a zero divide). See Sem_Eval spec for further details.

   --  Redundant_Use (Flag3-Sem)
   --     A flag present in Identifier nodes. Used only for identifiers
   --     referenced in use package clauses. Set to indicate that a use
   --     is redundant (and therefore need not be undone on scope exit)

   --  Return_Type (Node2-Sem)
   --     Present in N_Return_Statement node. For a procedure, this is set
   --     to Standard_Void_Type. For a function it references the entity
   --     for the returned type.

   --  Rounded_Result (Flag12-Sem)
   --     Present in N_Type_Conversion, N_Op_Divide and N_Op_Multiply nodes.
   --     Used in the fixed-point cases to indicate that the result must be
   --     rounded as a result of the use of the 'Round attribute. Also used
   --     for integer N_Op_Divide nodes to indicate that the result should
   --     be rounded to the nearest integer (breaking ties away from zero),
   --     rather than truncated towards zero as usual. These rounded integer
   --     operations are the result of expansion of rounded fixed-point
   --     divide, conersion and multiplication operations.

   --  Scope (Node3-Sem)
   --     Present in defining identifiers, defining character literals and
   --     defining operator symbols (i.e. in all entities). The entities of
   --     a scope all use this field to reference the corresponding scope
   --     entity. See Einfo for further details.

   --  Storage_Pool (Node1-Sem)
   --     Present in N_Allocato, N_Free_Statement and N_Return_Statement
   --     nodes. References the entity for the storage pool to be used for
   --     the allocate or free call or for the allocation of the returned
   --     value from a function. Empty indicates that the global default
   --     default pool is to be used.

   --  Treat_Fixed_As_Integer (Flag14-Sem)
   --     This flag appears in operator nodes for divide, multiply, mod and
   --     rem on fixed-point operands. It indicates that the operands are
   --     to be treated as integer values, ignoring small values. This flag
   --     is only set as a result of expansion of fixed-point operations.
   --     Typically a fixed-point multplication in the source generates
   --     subsidiary multiplication and division operations that work with
   --     the underlying integer values and have this flag set. Note that
   --     this flag is not needed on other arithmetic operations (add, neg,
   --     subtract etc) since in these cases it is always the case that fixed
   --     is treated as integer. The Etype field MUST be set if this flag
   --     is set. The analyzer knows to leave such nodes alone, and whoever
   --     makes them must set the correct Etype value.

   --  TSS_Elist (Elist3-Sem)
   --     Present in N_Freeze_Entity nodes. Holds an element list containing
   --     entries for each TSS (type support subprogram) associated with the
   --     frozen type. The elements of the list are the entities for the
   --     subprograms (see package Exp_TSS for further details). Set to
   --     No_Elist if there are no type support subprograms for the type
   --     or if the freeze node is not for a type.

      ---------------------
      -- 2.3  Identifier --
      ---------------------

      --  IDENTIFIER ::= IDENTIFIER_LETTER {[UNDERLINE] LETTER_OR_DIGIT}
      --  LETTER_OR_DIGIT ::= IDENTIFIER_LETTER | DIGIT

      --  An IDENTIFIER shall not be a reserved word

      --  In the Ada grammar identifiers are the bottom level tokens which
      --  have very few semantics. Actual program identifiers are direct
      --  names. If we were being 100% honest with the grammar, then we would
      --  have a node called N_Direct_Name which would point to an identifier.
      --  However, that's too many extra nodes, so we just use the N_Identifier
      --  node directly as a direct name, and it contains the expression fields
      --  and Entity field that correspond to its use as a direct name. In
      --  those few cases where identifiers appear in contexts where they are
      --  not direct names (pragmas, pragma argument associations, attribute
      --  references and attribute definition clauses), the Chars field of the
      --  node contains the Name_Id for the identifier name.

      --  Note: in GNAT, a reserved word can be treated as an identifier
      --  in two cases. First, an incorrect use of a reserved word as an
      --  identifier is diagnosed and then treated as a normal identifier.
      --  Second, an attribute designator of the form of a reserved word
      --  (access, delta, digits, range) is treated as an identifier.

      --  Note: The set of letters that is permitted in an identifier depends
      --  on the character set in use. See package Csets for full details.

      --  N_Identifier
      --  Sloc points to identifier
      --  Chars (Name1) contains the Name_Id for the identifier
      --  Entity (Node4-Sem)
      --  Redundant_Use (Flag3-Sem) set for redundant use clause
      --  Has_Private_View (Flag11-Sem) set in generic units.
      --  Is_Current_Instance (Flag14-Sem) set if entity is enclosing type.
      --  plus fields for expression

      --------------------------
      -- 2.4  Numeric Literal --
      --------------------------

      --  NUMERIC_LITERAL ::= DECIMAL_LITERAL | BASED_LITERAL

      ----------------------------
      -- 2.4.1  Decimal Literal --
      ----------------------------

      --  DECIMAL_LITERAL ::= NUMERAL [.NUMERAL] [EXPONENT]

      --  NUMERAL ::= DIGIT {[UNDERLINE] DIGIT}

      --  EXPONENT ::= E [+] NUMERAL | E - NUMERAL

      --  Decimal literals appear in the tree as either integer literal nodes
      --  or real literal nodes, depending on whether a period is present.

      --  Note: literal nodes appear as a result of direct use of literals
      --  in the source program, and also as the result of evaluating
      --  expressions at compile time. In the latter case, it is possible
      --  to construct real literals that have no syntactic representation
      --  using the standard literal format. Such literals are listed by
      --  Sprint using the notation [numerator / denominator].

      --  N_Integer_Literal
      --  Sloc points to literal
      --  Intval (Uint3) contains integer value of literal
      --  plus fields for expression

      --  N_Real_Literal
      --  Sloc points to literal
      --  Realval (Ureal3) contains real value of literal
      --  Corresponding_Integer_Value (Uint4-Sem)
      --  plus fields for expression

      --------------------------
      -- 2.4.2  Based Literal --
      --------------------------

      --  BASED_LITERAL ::=
      --   BASE # BASED_NUMERAL [.BASED_NUMERAL] # [EXPONENT]

      --  BASE ::= NUMERAL

      --  BASED_NUMERAL ::=
      --    EXTENDED_DIGIT {[UNDERLINE] EXTENDED_DIGIT}

      --  EXTENDED_DIGIT ::= DIGIT | A | B | C | D | E | F

      --  Based literals appear in the tree as either integer literal nodes
      --  or real literal nodes, depending on whether a period is present.

      ----------------------------
      -- 2.5  Character Literal --
      ----------------------------

      --  CHARACTER_LITERAL ::= ' GRAPHIC_CHARACTER '

      --  N_Character_Literal
      --  Sloc points to literal
      --  Chars (Name1) contains the Name_Id for the identifier
      --  Char_Literal_Value (Char_Code2) contains the literal value
      --  Entity (Node4-Sem)
      --  Has_Private_View (Flag11-Sem) set in generic units.
      --  plus fields for expression

      --  Note: the Entity field will be missing (and set to Empty) for
      --  character literals whose type is Standard.Wide_Character or
      --  Standard.Character or a type derived from one of these two.
      --  In this case the character literal stands for its own coding.
      --  The reason we take this irregular short cut is to avoid the
      --  need to build lots of junk defining character literal nodes.

      -------------------------
      -- 2.6  String Literal --
      -------------------------

      --  STRING LITERAL ::= "{STRING_ELEMENT}"

      --  A STRING_ELEMENT is either a pair of quotation marks ("), or a
      --  single GRAPHIC_CHARACTER other than a quotation mark.

      --  N_String_Literal
      --  Sloc points to literal
      --  Strval (Str3) contains Id of string value
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  plus fields for expression

      ------------------
      -- 2.7  Comment --
      ------------------

      --  A COMMENT starts with two adjacent hyphens and extends up to the
      --  end of the line. A COMMENT may appear on any line of a program.

      --  Comments are skipped by the scanner and do not appear in the tree.
      --  It is possible to reconstruct the position of comments with respect
      --  to the elements of the tree by using the source position (Sloc)
      --  pointers that appear in every tree node.

      -----------------
      -- 2.8  Pragma --
      -----------------

      --  PRAGMA ::= pragma IDENTIFIER
      --    [(PRAGMA_ARGUMENT_ASSOCIATION {, PRAGMA_ARGUMENT_ASSOCIATION})];

      --  Note that a pragma may appear in the tree anywhere a declaration
      --  or a statement may appear, as well as in some other situations
      --  which are explicitly documented.

      --  N_Pragma
      --  Sloc points to PRAGMA
      --  Chars (Name1) identifier name from pragma identifier
      --  Pragma_Argument_Associations (List2) (set to No_List if none)
      --  Debug_Statement (Node3-Sem)

      --------------------------------------
      -- 2.8  Pragma Argument Association --
      --------------------------------------

      --  PRAGMA_ARGUMENT_ASSOCIATION ::=
      --    [pragma_argument_IDENTIFIER =>] NAME
      --  | [pragma_argument_IDENTIFIER =>] EXPRESSION

      --  N_Pragma_Argument_Association
      --  Sloc points to first token in association
      --  Chars (Name1) (set to No_Name if no pragma argument identifier)
      --  Expression (Node3)

      ------------------------
      -- 2.9  Reserved Word --
      ------------------------

      --  Reserved words are parsed by the scanner, and returned as the
      --  corresponding token types (e.g. PACKAGE is returned as Tok_Package)

      ----------------------------
      -- 3.1  Basic Declaration --
      ----------------------------

      --  BASIC_DECLARATION ::=
      --    TYPE_DECLARATION          | SUBTYPE_DECLARATION
      --  | OBJECT_DECLARATION        | NUMBER_DECLARATION
      --  | SUBPROGRAM_DECLARATION    | ABSTRACT_SUBPROGRAM_DECLARATION
      --  | PACKAGE_DECLARATION       | RENAMING_DECLARATION
      --  | EXCEPTION_DECLARATION     | GENERIC_DECLARATION
      --  | GENERIC_INSTANTIATION

      --  Basic declaration also includes IMPLICIT_LABEL_DECLARATION
      --  see further description in section on semantic nodes.

      --  Also, in the tree that is constructed, a pragma may appear
      --  anywhere that a declaration may appear.

      ------------------------------
      -- 3.1  Defining Identifier --
      ------------------------------

      --  DEFINING_IDENTIFIER ::= IDENTIFIER

      --  A defining identifier is an entity, which has additional fields
      --  depending on the setting of the Ekind field. These additional
      --  fields are defined (and access subprograms declared) in package
      --  Entity_Info.

      --  Note: N_Defining_Identifier is an extended node whose fields are
      --  deliberate layed out to match the layout of fields in an ordinary
      --  N_Identifier node allowing for easy alteration of an identifier
      --  node into a defining identifier node. For details, see procedure
      --  Sinfo.CN.Change_Identifier_To_Defining_Identifier.

      --  N_Defining_Identifier
      --  Sloc points to identifier
      --  Chars (Name1) contains the Name_Id for the identifier
      --  Next_Entity (Node2-Sem)
      --  Scope (Node3-Sem)
      --  Homonym (Node4-Sem)
      --  Etype (Node5-Sem)

      -----------------------------
      -- 3.2.1  Type Declaration --
      -----------------------------

      --  TYPE_DECLARATION ::=
      --    FULL_TYPE_DECLARATION
      --  | INCOMPLETE_TYPE_DECLARATION
      --  | PRIVATE_TYPE_DECLARATION
      --  | PRIVATE_EXTENSION_DECLARATION

      ----------------------------------
      -- 3.2.1  Full Type Declaration --
      ----------------------------------

      --  FULL_TYPE_DECLARATION ::=
      --    type DEFINING_IDENTIFIER [KNOWN_DISCRIMINANT_PART]
      --      is TYPE_DEFINITION;
      --  | TASK_TYPE_DECLARATION
      --  | PROTECTED_TYPE_DECLARATION

      --  The full type declaration node is used only for the first case. The
      --  second case (concurrent type declaration), is represented directly
      --  by a task type declaration or a protected type declaration.

      --  N_Full_Type_Declaration
      --  Sloc points to TYPE
      --  Defining_Identifier (Node1)
      --  Discriminant_Specifications (List4) (set to No_List if none)
      --  Type_Definition (Node3)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      ----------------------------
      -- 3.2.1  Type Definition --
      ----------------------------

      --  TYPE_DEFINITION ::=
      --    ENUMERATION_TYPE_DEFINITION  | INTEGER_TYPE_DEFINITION
      --  | REAL_TYPE_DEFINITION         | ARRAY_TYPE_DEFINITION
      --  | RECORD_TYPE_DEFINITION       | ACCESS_TYPE_DEFINITION
      --  | DERIVED_TYPE_DEFINITION

      --------------------------------
      -- 3.2.2  Subtype Declaration --
      --------------------------------

      --  SUBTYPE_DECLARATION ::=
      --    subtype DEFINING_IDENTIFIER is SUBTYPE_INDICATION;

      --  The subtype indication field is set to Empty for subtypes
      --  declared in package Standard (Positive, Natural).

      --  N_Subtype_Declaration
      --  Sloc points to SUBTYPE
      --  Defining_Identifier (Node1)
      --  Subtype_Indication (Node5)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      -------------------------------
      -- 3.2.2  Subtype Indication --
      -------------------------------

      --  SUBTYPE_INDICATION ::= SUBTYPE_MARK [CONSTRAINT]

      --  Note: if no constraint is present, the subtype indication appears
      --  directly in the tree as a subtype mark. The N_Subtype_Indication
      --  node is used only if a constraint is present.

      --  Note: the reason that this node has expression fields is that a
      --  subtype indication can appear as an operand of a membership test.

      --  N_Subtype_Indication
      --  Sloc points to first token of subtype mark
      --  Subtype_Mark (Node4)
      --  Constraint (Node3)
      --  Etype (Node5-Sem)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      --  Note: Etype is a copy of the Etype field of the Subtype_Mark. The
      --  reason for this redundancy is so that in a list of array index types,
      --  the Etype can be uniformly accessed to determine the subscript type.
      --  This means that no Itype is constructed for the actual subtype that
      --  is created by the subtype indication. If such an Itype is required,
      --  it is constructed in the context in which the indication appears.

      --  Note: First_Itype is always Empty and Has_Dynamic_Itype is always
      --  False, since no Itypes are ever associated with this node. The
      --  reason that these fields are present is simply to enable the
      --  declaration of the N_Has_Itypes subtype range.

      -------------------------
      -- 3.2.2  Subtype Mark --
      -------------------------

      --  SUBTYPE_MARK ::= subtype_NAME

      -----------------------
      -- 3.2.2  Constraint --
      -----------------------

      --  CONSTRAINT ::= SCALAR_CONSTRAINT | COMPOSITE_CONSTRAINT

      ------------------------------
      -- 3.2.2  Scalar Constraint --
      ------------------------------

      --  SCALAR_CONSTRAINT ::=
      --    RANGE_CONSTRAINT | DIGITS_CONSTRAINT | DELTA_CONSTRAINT

      ---------------------------------
      -- 3.2.2  Composite Constraint --
      ---------------------------------

      --  COMPOSITE_CONSTRAINT ::=
      --    INDEX_CONSTRAINT | DISCRIMINANT_CONSTRAINT

      -------------------------------
      -- 3.3.1  Object Declaration --
      -------------------------------

      --  OBJECT_DECLARATION ::=
      --    DEFINING_IDENTIFIER_LIST : [aliased] [constant]
      --      SUBTYPE_INDICATION [:= EXPRESSION];
      --  | DEFINING_IDENTIFIER_LIST : [aliased] [constant]
      --      ARRAY_TYPE_DEFINITION [:= EXPRESSION];
      --  | SINGLE_TASK_DECLARATION
      --  | SINGLE_PROTECTED_DECLARATION

      --  Note: aliased is not permitted in Ada 83 mode

      --  The N_Object_Declaration node is only for the first two cases.
      --  Single task declaration is handled by P_Task (9.1)
      --  Single protected declaration is handled by P_protected (9.5)

      --  Although the syntax allows multiple identifiers in the list, the
      --  semantics is as though successive declarations were given with
      --  identical type definition and expression components. To simplify
      --  semantic processing, the parser represents a multiple declaration
      --  case as a sequence of single declarations, using the More_Ids and
      --  Prev_Ids flags to preserve the original source form as described
      --  in the section on "Handling of Defining Identifier Lists".

      --  Note: if a range check is required for the initialization
      --  expression then the Do_Range_Check flag is set in the Expression,
      --  with the check being done against the type given by the object
      --  definition, which is also the Etype of the defining identifier.

      --  N_Object_Declaration
      --  Sloc points to first identifier
      --  Defining_Identifier (Node1)
      --  Aliased_Present (Flag1) set if ALIASED appears
      --  Constant_Present (Flag17) set if CONSTANT appears
      --  Object_Definition (Node4) subtype indication/array type definition
      --  Expression (Node3) (set to Empty if not present)
      --  More_Ids (Flag5) (set to False if no more identifiers in list)
      --  Prev_Ids (Flag6) (set to False if no previous identifiers in list)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Object_Definition_Itypes (Node5-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  No_Default_Init (Flag7)

      -------------------------------------
      -- 3.3.1  Defining Identifier List --
      -------------------------------------

      --  DEFINING_IDENTIFIER_LIST ::=
      --    DEFINING_IDENTIFIER {, DEFINING_IDENTIFIER}

      -------------------------------
      -- 3.3.2  Number Declaration --
      -------------------------------

      --  NUMBER_DECLARATION ::=
      --    DEFINING_IDENTIFIER_LIST : constant := static_EXPRESSION;

      --  Although the syntax allows multiple identifiers in the list, the
      --  semantics is as though successive declarations were given with
      --  identical expressions. To simplify semantic processing, the parser
      --  represents a multiple declaration case as a sequence of single
      --  declarations, using the More_Ids and Prev_Ids flags to preserve
      --  the original source form as described in the section on "Handling
      --  of Defining Identifier Lists".

      --  N_Number_Declaration
      --  Sloc points to first identifier
      --  Defining_Identifier (Node1)
      --  Expression (Node3)
      --  More_Ids (Flag5) (set to False if no more identifiers in list)
      --  Prev_Ids (Flag6) (set to False if no previous identifiers in list)

      ----------------------------------
      -- 3.4  Derived Type Definition --
      ----------------------------------

      --  DERIVED_TYPE_DEFINITION ::=
      --    [abstract] new parent_SUBTYPE_INDICATION [RECORD_EXTENSION_PART]

      --  Note: ABSTRACT, record extension part not permitted in Ada 83 mode

      --  Note: a record extension part is required if ABSTRACT is present

      --  N_Derived_Type_Definition
      --  Sloc points to NEW
      --  Abstract_Present (Flag4)
      --  Subtype_Indication (Node5)
      --  Record_Extension_Part (Node3) (set to Empty if not present)

      ---------------------------
      -- 3.5  Range Constraint --
      ---------------------------

      --  RANGE_CONSTRAINT ::= range RANGE

      --  N_Range_Constraint
      --  Sloc points to RANGE
      --  Range_Expression (Node4)

      ----------------
      -- 3.5  Range --
      ----------------

      --  RANGE ::=
      --    RANGE_ATTRIBUTE_REFERENCE
      --  | SIMPLE_EXPRESSION .. SIMPLE_EXPRESSION

      --  Note: the case of a range given as a range attribute reference
      --  appears directly in the tree as an attribute reference.

      --  Note: the field name for a reference to a range is Range_Expression
      --  rather than Range, because range is a reserved keyword in Ada!

      --  Note: the reason that this node has expression fields is that a
      --  range can appear as an operand of a membership test. The Etype
      --  field is the type of the range (we do NOT construct an implicit
      --  subtype to represent the range exactly).

      --  N_Range
      --  Sloc points to ..
      --  Low_Bound (Node1)
      --  High_Bound (Node2)
      --  plus fields for expression

      --  Note: if the range appears in a context, such as a subtype
      --  declaration, where range checks are required on one or both of
      --  the expression fields, then type conversion nodes are inserted
      --  to represent the required checks.

      ----------------------------------------
      -- 3.5.1  Enumeration Type Definition --
      ----------------------------------------

      --  ENUMERATION_TYPE_DEFINITION ::=
      --    (ENUMERATION_LITERAL_SPECIFICATION
      --      {, ENUMERATION_LITERAL_SPECIFICATION})

      --  Note: the Literals field in the node described below is null for
      --  the case of the standard types CHARACTER and WIDE_CHARACTER, for
      --  which special processing handles these types as special cases.

      --  N_Enumeration_Type_Definition
      --  Sloc points to left parenthesis
      --  Literals (List1) (Empty for CHARACTER or WIDE_CHARACTER)

      ----------------------------------------------
      -- 3.5.1  Enumeration Literal Specification --
      ----------------------------------------------

      --  ENUMERATION_LITERAL_SPECIFICATION ::=
      --    DEFINING_IDENTIFIER | DEFINING_CHARACTER_LITERAL

      ---------------------------------------
      -- 3.5.1  Defining Character Literal --
      ---------------------------------------

      --  DEFINING_CHARACTER_LITERAL ::= CHARACTER_LITERAL

      --  A defining character literal is an entity, which has additional
      --  fields depending on the setting of the Ekind field. These
      --  additional fields are defined (and access subprograms declared)
      --  in package Entity_Info.

      --  Note: N_Defining_Character_Literal is an extended node whose fields
      --  are deliberate layed out to match the layout of fields in an ordinary
      --  N_Character_Literal node allowing for easy alteration of a character
      --  literal node into a defining character literal node. For details, see
      --  Sinfo.CN.Change_Character_Literal_To_Defining_Character_Literal.

      --  N_Defining_Character_Literal
      --  Sloc points to literal
      --  Chars (Name1) contains the Name_Id for the identifier
      --  Next_Entity (Node2-Sem)
      --  Scope (Node3-Sem)
      --  Homonym (Node4-Sem)
      --  Etype (Node5-Sem)

      ------------------------------------
      -- 3.5.4  Integer Type Definition --
      ------------------------------------

      --  Note: there is an error in this rule in the latest version of the
      --  grammar, so we have retained the old rule pending clarification.

      --  INTEGER_TYPE_DEFINITION ::=
      --    SIGNED_INTEGER_TYPE_DEFINITION
      --    MODULAR_TYPE_DEFINITION

      -------------------------------------------
      -- 3.5.4  Signed Integer Type Definition --
      -------------------------------------------

      --  SIGNED_INTEGER_TYPE_DEFINITION ::=
      --    range static_SIMPLE_EXPRESSION .. static_SIMPLE_EXPRESSION

      --  Note: the Low_Bound and High_Bound fields are set to Empty for
      --  integer types defined in package Standard.

      --  N_Signed_Integer_Type_Definition
      --  Sloc points to RANGE
      --  Low_Bound (Node1)
      --  High_Bound (Node2)

      -----------------------------------------
      -- 3.5.4  Unsigned Range Specification --
      -----------------------------------------

      --  MODULAR_TYPE_DEFINITION ::= mod static_EXPRESSION

      --  N_Modular_Type_Definition
      --  Sloc points to MOD
      --  Expression (Node3)

      ---------------------------------
      -- 3.5.6  Real Type Definition --
      ---------------------------------

      --  REAL_TYPE_DEFINITION ::=
      --    FLOATING_POINT_DEFINITION | FIXED_POINT_DEFINITION

      --------------------------------------
      -- 3.5.7  Floating Point Definition --
      --------------------------------------

      --  FLOATING_POINT_DEFINITION ::=
      --    digits static_SIMPLE_EXPRESSION [REAL_RANGE_SPECIFICATION]

      --  Note: The Digits_Expression and Real_Range_Specifications fields
      --  are set to Empty for floating-point types declared in Standard.

      --  N_Floating_Point_Definition
      --  Sloc points to DIGITS
      --  Digits_Expression (Node2)
      --  Real_Range_Specification (Node4) (set to Empty if not present)

      -------------------------------------
      -- 3.5.7  Real Range Specification --
      -------------------------------------

      --  REAL_RANGE_SPECIFICATION ::=
      --    range static_SIMPLE_EXPRESSION .. static_SIMPLE_EXPRESSION

      --  N_Real_Range_Specification
      --  Sloc points to RANGE
      --  Low_Bound (Node1)
      --  High_Bound (Node2)

      -----------------------------------
      -- 3.5.9  Fixed Point Definition --
      -----------------------------------

      --  FIXED_POINT_DEFINITION ::=
      --    ORDINARY_FIXED_POINT_DEFINITION | DECIMAL_FIXED_POINT_DEFINITION

      --------------------------------------------
      -- 3.5.9  Ordinary Fixed Point Definition --
      --------------------------------------------

      --  ORDINARY_FIXED_POINT_DEFINITION ::=
      --    delta static_EXPRESSION REAL_RANGE_SPECIFICATION

      --  Note: In Ada 83, the EXPRESSION must be a SIMPLE_EXPRESSION

      --  Note: the Delta_Expression and Real_Range_Specification fields
      --  are set to Empty for fixed point types declared in Standard.

      --  N_Ordinary_Fixed_Point_Definition
      --  Sloc points to DELTA
      --  Delta_Expression (Node3)
      --  Real_Range_Specification (Node4)

      -------------------------------------------
      -- 3.5.9  Decimal Fixed Point Definition --
      -------------------------------------------

      --  DECIMAL_FIXED_POINT_DEFINITION ::=
      --    delta static_EXPRESSION
      --      digits static_EXPRESSION [REAL_RANGE_SPECIFICATION]

      --  Note: decimal types are not permitted in Ada 83 mode

      --  N_Decimal_Fixed_Point_Definition
      --  Sloc points to DELTA
      --  Delta_Expression (Node3)
      --  Digits_Expression (Node2)
      --  Real_Range_Specification (Node4) (set to Empty if not present)

      ------------------------------
      -- 3.5.9  Digits Constraint --
      ------------------------------

      --  DIGITS_CONSTRAINT ::=
      --    digits static_EXPRESSION [RANGE_CONSTRAINT]

      --  Note: in Ada 83, the EXPRESSION must be a SIMPLE_EXPRESSION
      --  Note: in Ada 95, reduced accuracy subtypes are obsolescent

      --  N_Digits_Constraint
      --  Sloc points to DIGITS
      --  Digits_Expression (Node2)
      --  Range_Constraint (Node4) (set to Empty if not present)

      --------------------------------
      -- 3.6  Array Type Definition --
      --------------------------------

      --  ARRAY_TYPE_DEFINITION ::=
      --    UNCONSTRAINED_ARRAY_DEFINITION | CONSTRAINED_ARRAY_DEFINITION

      -----------------------------------------
      -- 3.6  Unconstrained Array Definition --
      -----------------------------------------

      --  UNCONSTRAINED_ARRAY_DEFINITION ::=
      --    array (INDEX_SUBTYPE_DEFINITION {, INDEX_SUBTYPE_DEFINITION}) of
      --      COMPONENT_DEFINITION

      --  Note: dimensionality of array is indicated by number of entries in
      --  the Subtype_Marks list, which has one entry for each dimension.

      --  N_Unconstrained_Array_Definition
      --  Sloc points to ARRAY
      --  Subtype_Marks (List2)
      --  Aliased_Present (Flag1) from component definition
      --  Subtype_Indication (Node5) from component definition

      -----------------------------------
      -- 3.6  Index Subtype Definition --
      -----------------------------------

      --  INDEX_SUBTYPE_DEFINITION ::= SUBTYPE_MARK range <>

      --  There is no explicit node in the tree for an index subtype
      --  definition since the N_Unconstrained_Array_Definition node
      --  incorporates the type marks which appear in this context.

      ---------------------------------------
      -- 3.6  Constrained Array Definition --
      ---------------------------------------

      --  CONSTRAINED_ARRAY_DEFINITION ::=
      --    array (DISCRETE_SUBTYPE_DEFINITION
      --      {, DISCRETE_SUBTYPE_DEFINITION})
      --        of COMPONENT_DEFINITION

      --  Note: dimensionality of array is indicated by number of entries
      --  in the Discrete_Subtype_Definitions list, which has one entry
      --  for each dimension.

      --  N_Constrained_Array_Definition
      --  Sloc points to ARRAY
      --  Discrete_Subtype_Definitions (List2)
      --  Aliased_Present (Flag1) from component definition
      --  Subtype_Indication (Node5) from component definition

      --------------------------------------
      -- 3.6  Discrete Subtype Definition --
      --------------------------------------

      --  DISCRETE_SUBTYPE_DEFINITION ::=
      --    discrete_SUBTYPE_INDICATION | RANGE

      -------------------------------
      -- 3.6  Component Definition --
      -------------------------------

      --  COMPONENT_DEFINITION ::= [aliased] SUBTYPE_INDICATION

      --  There is no explicit node in the tree for a component definition.
      --  Instead the subtype indication appears directly, and the ALIASED
      --  indication (Aliased_Present flag) is in the parent node.

      --  Note: although the syntax does not permit a component definition to
      --  be an anonymous array (and the parser will diagnose such an attempt
      --  with an appropriate message), it is possible for anonymous arrays
      --  to appear as component definitions. The semantics and back end handle
      --  this case properly, and the expander in fact generates such cases.

      -----------------------------
      -- 3.6.1  Index Constraint --
      -----------------------------

      --  INDEX_CONSTRAINT ::= (DISCRETE_RANGE {, DISCRETE_RANGE})

      --  It is not in general possible to distinguish between discriminant
      --  constraints and index constraints at parse time, since a simple
      --  name could be either the subtype mark of a discrete range, or an
      --  expression in a discriminant association with no name. Either
      --  entry appears simply as the name, and the semantic parse must
      --  distinguish between the two cases. Thus we use a common tree
      --  node format for both of these constraint types.

      --  See Discriminant_Constraint for format of node

      ---------------------------
      -- 3.6.1  Discrete Range --
      ---------------------------

      --  DISCRETE_RANGE ::= discrete_SUBTYPE_INDICATION | RANGE

      ----------------------------
      -- 3.7  Discriminant Part --
      ----------------------------

      --  DISCRIMINANT_PART ::=
      --    UNKNOWN_DISCRIMINANT_PART | KNOWN_DISCRIMINANT_PART

      ------------------------------------
      -- 3.7  Unknown Discriminant Part --
      ------------------------------------

      --  UNKNOWN_DISCRIMINANT_PART ::= (<>)

      --  Note: unknown discriminant parts are not permitted in Ada 83 mode

      --  There is no explicit node in the tree for an unknown discriminant
      --  part. Instead the Unknown_Discriminants_Present flag is set in the
      --  parent node.

      ----------------------------------
      -- 3.7  Known Discriminant Part --
      ----------------------------------

      --  KNOWN_DISCRIMINANT_PART ::=
      --    (DISCRIMINANT_SPECIFICATION {; DISCRIMINANT_SPECIFICATION})

      -------------------------------------
      -- 3.7  Discriminant Specification --
      -------------------------------------

      --  DISCRIMINANT_SPECIFICATION ::=
      --    DEFINING_IDENTIFIER_LIST : SUBTYPE_MARK
      --      [:= DEFAULT_EXPRESSION]
      --  | DEFINING_IDENTIFIER_LIST : ACCESS_DEFINITION
      --      [:= DEFAULT_EXPRESSION]

      --  Although the syntax allows multiple identifiers in the list, the
      --  semantics is as though successive specifications were given with
      --  identical type definition and expression components. To simplify
      --  semantic processing, the parser represents a multiple declaration
      --  case as a sequence of single specifications, using the More_Ids and
      --  Prev_Ids flags to preserve the original source form as described
      --  in the section on "Handling of Defining Identifier Lists".

      --  N_Discriminant_Specification
      --  Sloc points to first identifier
      --  Defining_Identifier (Node1)
      --  Discriminant_Type (Node2) subtype mark or
      --    access parameter definition
      --  Expression (Node3) (set to Empty if no default expression)
      --  More_Ids (Flag5) (set to False if no more identifiers in list)
      --  Prev_Ids (Flag6) (set to False if no previous identifiers in list)

      -----------------------------
      -- 3.7  Default Expression --
      -----------------------------

      --  DEFAULT_EXPRESSION ::= EXPRESSION

      ------------------------------------
      -- 3.7.1  Discriminant Constraint --
      ------------------------------------

      --  DISCRIMINANT_CONSTRAINT ::=
      --    (DISCRIMINANT_ASSOCIATION {, DISCRIMINANT_ASSOCIATION})

      --  It is not in general possible to distinguish between discriminant
      --  constraints and index constraints at parse time, since a simple
      --  name could be either the subtype mark of a discrete range, or an
      --  expression in a discriminant association with no name. Either
      --  entry appears simply as the name, and the semantic parse must
      --  distinguish between the two cases. Thus we use a common tree
      --  node format for both of these constraint types.

      --  N_Index_Or_Discriminant_Constraint
      --  Sloc points to left paren
      --  Constraints (List1) points to list of discrete ranges or
      --    discriminant associations

      -------------------------------------
      -- 3.7.1  Discriminant Association --
      -------------------------------------

      --  DISCRIMINANT_ASSOCIATION ::=
      --    [discriminant_SELECTOR_NAME
      --      {| discriminant_SELECTOR_NAME} =>] EXPRESSION

      --  Note: a discriminant association that has no selector name list
      --  appears directly as an expression in the tree.

      --  N_Discriminant_Association
      --  Sloc points to first token of discriminant association
      --  Selector_Names (List1) (always non-empty, since if no selector
      --   names are present, this node is not used, see comment above)
      --  Expression (Node3)

      ---------------------------------
      -- 3.8  Record Type Definition --
      ---------------------------------

      --  RECORD_TYPE_DEFINITION ::=
      --    [[abstract] tagged] [limited] RECORD_DEFINITION

      --  Note: ABSTRACT, TAGGED, LIMITED are not permitted in Ada 83 mode

      --  There is no explicit node in the tree for a record type definition.
      --  Instead the flags for Tagged_Present and Limited_Present appear in
      --  the N_Record_Definition node for a record definition appearing in
      --  the context of a record type definition.

      ----------------------------
      -- 3.8  Record Definition --
      ----------------------------

      --  RECORD_DEFINITION ::=
      --    record
      --      COMPONENT_LIST
      --    end record
      --  | null record

      --  Note: the Abstract_Present, Tagged_Present and Limited_Present
      --  flags appear only for a record definition appearing in a record
      --  type definition.

      --  Note: the NULL RECORD case is not permitted in Ada 83

      --  N_Record_Definition
      --  Sloc points to RECORD or NULL
      --  Abstract_Present (Flag4)
      --  Tagged_Present (Flag1)
      --  Limited_Present (Flag17)
      --  Component_List (Node1) empty in null record case
      --  Null_Present (Flag3) set in null record case

      -------------------------
      -- 3.8  Component List --
      -------------------------

      --  COMPONENT_LIST ::=
      --    COMPONENT_ITEM {COMPONENT_ITEM}
      --  | {COMPONENT_ITEM} VARIANT_PART
      --  | null;

      --  N_Component_List
      --  Sloc points to first token of component list
      --  Component_Items (List3)
      --  Variant_Part (Node4) (set to Empty if no variant part)
      --  Null_Present (Flag3)

      -------------------------
      -- 3.8  Component Item --
      -------------------------

      --  COMPONENT_ITEM ::= COMPONENT_DECLARATION | REPRESENTATION_CLAUSE

      --------------------------------
      -- 3.8  Component Declaration --
      --------------------------------

      --  COMPONENT_DECLARATION ::=
      --    DEFINING_IDENTIFIER_LIST : COMPONENT_DEFINITION
      --      [:= DEFAULT_EXPRESSION]

      --  Note: although the syntax does not permit a component definition to
      --  be an anonymous array (and the parser will diagnose such an attempt
      --  with an appropriate message), it is possible for anonymous arrays
      --  to appear as component definitions. The semantics and back end handle
      --  this case properly, and the expander in fact generates such cases.

      --  Although the syntax allows multiple identifiers in the list, the
      --  semantics is as though successive declarations were given with the
      --  same component definition and expression components. To simplify
      --  semantic processing, the parser represents a multiple declaration
      --  case as a sequence of single declarations, using the More_Ids and
      --  Prev_Ids flags to preserve the original source form as described
      --  in the section on "Handling of Defining Identifier Lists".

      --  N_Component_Declaration
      --  Sloc points to identifier
      --  Defining_Identifier (Node1)
      --  Aliased_Present (Flag1) from component definition
      --  Subtype_Indication (Node5) from component definition
      --  Expression (Node3) (set to Empty if no default expression)
      --  More_Ids (Flag5) (set to False if no more identifiers in list)
      --  Prev_Ids (Flag6) (set to False if no previous identifiers in list)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      -------------------------
      -- 3.8.1  Variant Part --
      -------------------------

      --  VARIANT_PART ::=
      --    case discriminant_DIRECT_NAME is
      --      VARIANT
      --      {VARIANT}
      --    end case;

      --  N_Variant_Part
      --  Sloc points to CASE
      --  Name (Node2)
      --  Variants (List1)

      --------------------
      -- 3.8.1  Variant --
      --------------------

      --  VARIANT ::=
      --    when DISCRETE_CHOICE_LIST =>
      --      COMPONENT_LIST

      --  N_Variant
      --  Sloc points to WHEN
      --  Discrete_Choices (List4)
      --  Component_List (Node1)
      --  Enclosing_Variant (Node2-Sem)

      ---------------------------------
      -- 3.8.1  Discrete Choice List --
      ---------------------------------

      --  DISCRETE_CHOICE_LIST ::= DISCRETE_CHOICE {| DISCRETE_CHOICE}

      ----------------------------
      -- 3.8.1  Discrete Choice --
      ----------------------------

      --  DISCRETE_CHOICE ::= EXPRESSION | DISCRETE_RANGE | others

      --  Note: in Ada 83 mode, the expression must be a simple expression

      --  The only choice that appears explicitly is the OTHERS choice, as
      --  defined here. Other cases of discrete choice (expression and
      --  discrete range) appear directly. This production is also used
      --  for the OTHERS possibility of an exception choice.

      --  Note: in accordance with the syntax, the parser does not check that
      --  OTHERS appears at the end on its own in a choice list context. This
      --  is a semantic check.

      --  N_Others_Choice
      --  Sloc points to OTHERS
      --  Others_Discrete_Choices (List1-Sem)

      ----------------------------------
      -- 3.9.1  Record Extension Part --
      ----------------------------------

      --  RECORD_EXTENSION_PART ::= with RECORD_DEFINITION

      --  Note: record extension parts are not permitted in Ada 83 mode

      ----------------------------------
      -- 3.10  Access Type Definition --
      ----------------------------------

      --  ACCESS_TYPE_DEFINITION ::=
      --    ACCESS_TO_OBJECT_DEFINITION
      --  | ACCESS_TO_SUBPROGRAM_DEFINITION

      ---------------------------------------
      -- 3.10  Access To Object Definition --
      ---------------------------------------

      --  ACCESS_TO_OBJECT_DEFINITION ::=
      --    access [GENERAL_ACCESS_MODIFIER] SUBTYPE_INDICATION

      --  N_Access_To_Object_Definition
      --  Sloc points to ACCESS
      --  All_Present (Flag1)
      --  Subtype_Indication (Node5)
      --  Constant_Present (Flag17)

      -----------------------------------
      -- 3.10  General Access Modifier --
      -----------------------------------

      --  GENERAL_ACCESS_MODIFIER ::= all | constant

      --  Note: general access modifiers are not permitted in Ada 83 mode

      --  There is no explicit node in the tree for general access modifier.
      --  Instead the All_Present or Constant_Present flags are set in the
      --  parent node.

      -------------------------------------------
      -- 3.10  Access To Subprogram Definition --
      -------------------------------------------

      --  ACCESS_TO_SUBPROGRAM_DEFINITION
      --    access [protected] procedure PARAMETER_PROFILE
      --  | access [protected] function PARAMETER_AND_RESULT_PROFILE

      --  Note: access to subprograms are not permitted in Ada 83 mode

      --  N_Access_Function_Definition
      --  Sloc points to ACCESS
      --  Protected_Present (Flag1)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  Parameter_Specifications (List3) (set to No_List if no formal part)
      --  Subtype_Mark (Node4) result subtype

      --  N_Access_Procedure_Definition
      --  Sloc points to ACCESS
      --  Protected_Present (Flag1)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  Parameter_Specifications (List3) (set to No_List if no formal part)

      -----------------------------
      -- 3.10  Access Definition --
      -----------------------------

      --  ACCESS_DEFINITION ::= access SUBTYPE_MARK

      --  N_Access_Definition
      --  Sloc points to ACCESS
      --  Subtype_Mark (Node4)

      -----------------------------------------
      -- 3.10.1  Incomplete Type Declaration --
      -----------------------------------------

      --  INCOMPLETE_TYPE_DECLARATION ::=
      --    type DEFINING_IDENTIFIER [DISCRIMINANT_PART];

      --  N_Incomplete_Type_Declaration
      --  Sloc points to TYPE
      --  Defining_Identifier (Node1)
      --  Discriminant_Specifications (List4) (set to No_List if no
      --   discriminant part, or if the discriminant part is an
      --   unknown discriminant part)
      --  Unknown_Discriminants_Present (Flag3) set if (<>) discriminant
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      ----------------------------
      -- 3.11  Declarative Part --
      ----------------------------

      --  DECLARATIVE_PART ::= {DECLARATIVE_ITEM}

      --  Note: although the parser enforces the syntactic requirement that
      --  a declarative part can contain only declarations, the semantic
      --  processing may add statements to the list of actions in a
      --  declarative part, so the code generator should be prepared
      --  to accept a statement in this position.

      ----------------------------
      -- 3.11  Declarative Item --
      ----------------------------

      --  DECLARATIVE_ITEM ::= BASIC_DECLARATIVE_ITEM | BODY

      ----------------------------------
      -- 3.11  Basic Declarative Item --
      ----------------------------------

      --  BASIC_DECLARATIVE_ITEM ::=
      --    BASIC_DECLARATION | REPRESENTATION_CLAUSE | USE_CLAUSE

      ----------------
      -- 3.11  Body --
      ----------------

      --  BODY ::= PROPER_BODY | BODY_STUB

      -----------------------
      -- 3.11  Proper Body --
      -----------------------

      --  PROPER_BODY ::=
      --    SUBPROGRAM_BODY | PACKAGE_BODY | TASK_BODY | PROTECTED_BODY

      ---------------
      -- 4.1  Name --
      ---------------

      --  NAME ::=
      --    DIRECT_NAME        | EXPLICIT_DEREFERENCE
      --  | INDEXED_COMPONENT  | SLICE
      --  | SELECTED_COMPONENT | ATTRIBUTE_REFERENCE
      --  | TYPE_CONVERSION    | FUNCTION_CALL
      --  | CHARACTER_LITERAL

      ----------------------
      -- 4.1  Direct Name --
      ----------------------

      --  DIRECT_NAME ::= IDENTIFIER | OPERATOR_SYMBOL

      -----------------
      -- 4.1  Prefix --
      -----------------

      --  PREFIX ::= NAME | IMPLICIT_DEREFERENCE

      -------------------------------
      -- 4.1  Explicit Dereference --
      -------------------------------

      --  EXPLICIT_DEREFERENCE ::= NAME . all

      --  N_Explicit_Dereference
      --  Sloc points to ALL
      --  Prefix (Node3)
      --  Do_Access_Check (Flag11-Sem)
      --  plus fields for expression

      -------------------------------
      -- 4.1  Implicit Dereference --
      -------------------------------

      --  IMPLICIT_DEREFERENCE ::= NAME

      ------------------------------
      -- 4.1.1  Indexed Component --
      ------------------------------

      --  INDEXED_COMPONENT ::= PREFIX (EXPRESSION {, EXPRESSION})

      --  Note: the parser may generate this node in some situations where it
      --  should be a function call. The semantic  pass must correct this
      --  misidentification (which is inevitable at the parser level).

      --  N_Indexed_Component
      --  Sloc points to first token of prefix
      --  Prefix (Node3)
      --  Expressions (List1)
      --  Do_Access_Check (Flag11-Sem)
      --  plus fields for expression

      --  Note: if any of the subscripts requires a range check, then the
      --  Do_Range_Check flag is set on the corresponding expression, with
      --  the index type being determined from the type of the Prefix, which
      --  references the array being indexed.

      ------------------
      -- 4.1.2  Slice --
      ------------------

      --  SLICE ::= PREFIX (DISCRETE_RANGE)

      --  Note: an implicit subtype is created to describe the resulting
      --  type, so that the bounds of this type are the bounds of the slice.

      --  N_Slice
      --  Sloc points to first token of prefix
      --  Prefix (Node3)
      --  Discrete_Range (Node4)
      --  Do_Access_Check (Flag11-Sem)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  plus fields for expression

      -------------------------------
      -- 4.1.3  Selected Component --
      -------------------------------

      --  SELECTED_COMPONENT ::= PREFIX . SELECTOR_NAME

      --  Note: selected components that are semantically expanded names get
      --  changed during semantic processing into the separate N_Expanded_Name
      --  node. See description of this node in the section on semantic nodes.

      --  N_Selected_Component
      --  Sloc points to period
      --  Prefix (Node3)
      --  Selector_Name (Node2)
      --  Do_Access_Check (Flag11-Sem)
      --  Do_Discriminant_Check (Flag3-Sem)
      --  plus fields for expression

      --------------------------
      -- 4.1.3  Selector Name --
      --------------------------

      --  SELECTOR_NAME ::= IDENTIFIER | CHARACTER_LITERAL | OPERATOR_SYMBOL

      --------------------------------
      -- 4.1.4  Attribute Reference --
      --------------------------------

      --  ATTRIBUTE_REFERENCE ::= PREFIX ' ATTRIBUTE_DESIGNATOR

      --  Note: the syntax is quite ambiguous at this point. Consider:

      --    A'Length (X)  X is part of the attribute designator
      --    A'Pos (X)     X is an explicit actual parameter of function A'Pos
      --    A'Class (X)   X is the expression of a type conversion

      --  It would be possible for the parser to distinguish these cases
      --  by looking at the attribute identifier. However, that would mean
      --  more work in introducing new implementation defined attributes,
      --  and also it would mean that special processing for attributes
      --  would be scattered around, instead of being centralized in the
      --  semantic routine that handles an N_Attribute_Reference node.
      --  Consequently, the parser in all the above cases stores the
      --  expression (X in these examples) as a single element list in
      --  in the Expressions field of the N_Attribute_Reference node.

      --  Similarly, for attributes like Max which take two arguments,
      --  we store the two arguments as a two element list in the
      --  Expressions field. Of course it is clear at parse time that
      --  this case is really a function call with an attribute as the
      --  prefix, but it turns out to be convenient to handle the two
      --  argument case in a similar manner to the one argument case,
      --  and indeed in general the parser will accept any number of
      --  expressions in this position and store them as a list in the
      --  attribute reference node. This allows for future addition of
      --  attributes that take more than two arguments.

      --  Note: named associates are not permitted in function calls where
      --  the function is an attribute (see RM 6.4(3)) so it is legitimate
      --  to skip the normal subprogram argument processing.

      --  Note: for the attributes whose designators are technically keywords,
      --  i.e. digits, access, delta, range, the Chars field contains the
      --  corresponding name, even though no identifier is involved.

      --  See Sem_Attr for a complete description of which attributes are
      --  passed onto Gigi, and which are handled entirely by the front end.

      --  N_Attribute_Reference
      --  Sloc points to apostrophe
      --  Prefix (Node3)
      --  Attribute_Name (Name2) identifier name from attribute designator
      --  Expressions (List1) (set to No_List if no associated expressions)
      --  Entity (Node4-Sem) used if the attribute yields a type
      --  Do_Access_Check (Flag11-Sem)
      --  Do_Overflow_Check (Flag17-Sem)
      --  plus fields for expression

      ---------------------------------
      -- 4.1.4  Attribute Designator --
      ---------------------------------

      --  ATTRIBUTE_DESIGNATOR ::=
      --    IDENTIFIER [(static_EXPRESSION)]
      --  | access | delta | digits

      --  There is no explicit node in the tree for an attribute designator.
      --  Instead the Chars and Expressions fields of the parent node
      --  (N_Attribute_Reference node) hold the information.

      --  Note: if ACCESS, DELTA or DIGITS appears in an attribute
      --  designator, then they are treated as identifiers internally
      --  rather than the keywords of the same name.

      --------------------------------------
      -- 4.1.4  Range Attribute Reference --
      --------------------------------------

      --  RANGE_ATTRIBUTE_REFERENCE ::= PREFIX ' RANGE_ATTRIBUTE_DESIGNATOR

      --  A range attribute reference is represented in the tree using the
      --  normal N_Attribute_Reference node.

      ---------------------------------------
      -- 4.1.4  Range Attribute Designator --
      ---------------------------------------

      --  RANGE_ATTRIBUTE_DESIGNATOR ::= Range [(static_EXPRESSION)]

      --  A range attribute designator is represented in the tree using the
      --  normal N_Attribute_Reference node.

      --------------------
      -- 4.3  Aggregate --
      --------------------

      --  AGGREGATE ::=
      --    RECORD_AGGREGATE | EXTENSION_AGGREGATE | ARRAY_AGGREGATE

      -----------------------------
      -- 4.3.1  Record Aggregate --
      -----------------------------

      --  RECORD_AGGREGATE ::= (RECORD_COMPONENT_ASSOCIATION_LIST)

      --  N_Aggregate
      --  Sloc points to left parenthesis
      --  Expressions (List1) (set to No_List if none or null record case)
      --  Component_Associations (List4) (set to No_List if none)
      --  Null_Record_Present (Flag17)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Aggregate_Bounds (Node3-Sem)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  plus fields for expression

      --  Note: this structure is used for both record and array aggregates
      --  since the two cases are not separable by the parser. The parser
      --  makes no attempt to enforce consistency here, so it is up to the
      --  semantic phase to make sure that the aggregate is consistent (i.e.
      --  that it is not a "half-and-half" case that mixes record and array
      --  syntax. In particular, for a record aggregate, the expressions
      --  field will be set if there are positional associations.

      ----------------------------------------------
      -- 4.3.1  Record Component Association List --
      ----------------------------------------------

      --  RECORD_COMPONENT_ASSOCIATION_LIST ::=
      --     RECORD_COMPONENT_ASSOCIATION {, RECORD_COMPONENT_ASSOCIATION}
      --   | null record

      --  There is no explicit node in the tree for a record component
      --  association list. Instead the Null_Record_Present flag is set in
      --  the parent node for the NULL RECORD case.

      ------------------------------------------------------
      -- 4.3.1  Record Component Association (also 4.3.3) --
      ------------------------------------------------------

      --  RECORD_COMPONENT_ASSOCIATION ::=
      --    [COMPONENT_CHOICE_LIST =>] EXPRESSION

      --  N_Component_Association
      --  Sloc points to first selector name
      --  Choices (List1)
      --  Expression (Node3)

      --  Note: this structure is used for both record component associations
      --  and array component associations, since the two cases aren't always
      --  separable by the parser. The choices list may represent either a
      --  list of selector names in the record aggregate case, or a list of
      --  discrete choices in the array aggregate case or an N_Others_Choice
      --  node (which appears as a singleton list).

      ------------------------------------
      --  4.3.1  Commponent Choice List --
      ------------------------------------

      --  COMPONENT_CHOICE_LIST ::=
      --    component_SELECTOR_NAME {| component_SELECTOR_NAME}
      --  | others

      --  The entries of a component choice list appear in the Choices list
      --  of the associated N_Component_Association, as either selector
      --  names, or as an N_Others_Choice node.

      --------------------------------
      -- 4.3.2  Extension Aggregate --
      --------------------------------

      --  EXTENSION_AGGREGATE ::=
      --    (ANCESTOR_PART with RECORD_COMPONENT_ASSOCIATION_LIST)

      --  Note: extension aggregates are not permitted in Ada 83 mode

      --  N_Extension_Aggregate
      --  Sloc points to left parenthesis
      --  Ancestor_Part (Node3)
      --  Expressions (List1) (set to No_List if none or null record case)
      --  Component_Associations (List4) (set to No_List if none)
      --  Null_Record_Present (Flag17)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  plus fields for expression

      --------------------------
      -- 4.3.2  Ancestor Part --
      --------------------------

      --  ANCESTOR_PART ::= EXPRESSION | SUBTYPE_MARK

      ----------------------------
      -- 4.3.3  Array Aggregate --
      ----------------------------

      --  ARRAY_AGGREGATE ::=
      --    POSITIONAL_ARRAY_AGGREGATE | NAMED_ARRAY_AGGREGATE

      ---------------------------------------
      -- 4.3.3  Positional Array Aggregate --
      ---------------------------------------

      --  POSITIONAL_ARRAY_AGGREGATE ::=
      --    (EXPRESSION, EXPRESSION {, EXPRESSION})
      --  | (EXPRESSION {, EXPRESSION}, others => EXPRESSION)

      --  See Record_Aggregate (4.3.1) for node structure

      ----------------------------------
      -- 4.3.3  Named Array Aggregate --
      ----------------------------------

      --  NAMED_ARRAY_AGGREGATE ::=
      --  | (ARRAY_COMPONENT_ASSOCIATION {, ARRAY_COMPONENT_ASSOCIATION})

      --  See Record_Aggregate (4.3.1) for node structure

      ----------------------------------------
      -- 4.3.3  Array Component Association --
      ----------------------------------------

      --  ARRAY_COMPONENT_ASSOCIATION ::=
      --    DISCRETE_CHOICE_LIST => EXPRESSION

      --  See Record_Component_Association (4.3.1) for node structure

      --------------------------------------------------
      -- 4.4  Expression/Relation/Term/Factor/Primary --
      --------------------------------------------------

      --  EXPRESSION ::=
      --    RELATION {and RELATION} | RELATION {and then RELATION}
      --  | RELATION {or RELATION}  | RELATION {or else RELATION}
      --  | RELATION {xor RELATION}

      --  RELATION ::=
      --    SIMPLE_EXPRESSION [RELATIONAL_OPERATOR SIMPLE_EXPRESSION]
      --  | SIMPLE_EXPRESSION [not] in RANGE
      --  | SIMPLE_EXPRESSION [not] in SUBTYPE_MARK

      --  SIMPLE_EXPRESSION ::=
      --    [UNARY_ADDING_OPERATOR] TERM {BINARY_ADDING_OPERATOR TERM}

      --  TERM ::= FACTOR {MULTIPLYING_OPERATOR FACTOR}

      --  FACTOR ::= PRIMARY [** PRIMARY] | abs PRIMARY | not PRIMARY

      --  No nodes are generated for any of these constructs. Instead, the
      --  node for the operator appears directly. When we refer to an
      --  expression in this description, we mean any of the possible
      --  consistuent components of an expression (e.g. identifier is
      --  an example of an expression).

      ------------------
      -- 4.4  Primary --
      ------------------

      --  PRIMARY ::=
      --    NUMERIC_LITERAL  | null
      --  | STRING_LITERAL   | AGGREGATE
      --  | NAME             | QUALIFIED_EXPRESSION
      --  | ALLOCATOR        | (EXPRESSION)

      --  Usually there is no explicit node in the tree for primary. Instead
      --  the constituent (e.g. AGGREGATE) appears directly. There are two
      --  exceptions. First, there is an explicit node for a null primary.

      --  N_Null
      --  Sloc points to NULL
      --  plus fields for expression

      --  Second, the case of (EXPRESSION) is handled specially. Ada requires
      --  that the parser keep track of which subexpressions are enclosed
      --  in parentheses, and how many levels of parentheses are used. This
      --  information is required for optimization purposes, and also for
      --  some semantic checks (e.g. (((1))) in a procedure spec does not
      --  conform with ((((1)))) in the body).

      --  The parentheses are recorded by keeping a Paren_Count field in every
      --  subexpression node (it is actually present in all nodes, but only
      --  used in subexpression nodes). This count records the number of
      --  levels of parentheses. If the number of levels in the source exceeds
      --  the maximum accomodated by this count, then the count is simply left
      --  at the maximum value. This means that there are some pathalogical
      --  cases of failure to detect conformance failures (e.g. an expression
      --  with 500 levels of parens will conform with one with 501 levels),
      --  but we do not need to lose sleep over this.

      --  Historical note: in versions of GNAT prior to 1.75, there was a node
      --  type N_Parenthesized_Expression used to accurately record unlimited
      --  numbers of levels of parentheses. However, it turned out to be a
      --  real nuisance to have to take into account the possible presence of
      --  this node during semantic analysis, since basically parentheses have
      --  zero relevance to semantic analysis.

      --  Note: the level of parentheses always present in things like
      --  aggregates does not count, only the parentheses in the primary
      --  (EXPRESSION) affect the setting of the Paren_Count field.

      --------------------------------------
      -- 4.5  Short Circuit Control Forms --
      --------------------------------------

      --  EXPRESSION ::=
      --    RELATION {and then RELATION} | RELATION {or else RELATION}

      --  N_And_Then
      --  Sloc points to AND of AND THEN
      --  Left_Opnd (Node2)
      --  Right_Opnd (Node3)
      --  Actions (List1-Sem)
      --  plus fields for expression

      --  N_Or_Else
      --  Sloc points to OR of OR ELSE
      --  Left_Opnd (Node2)
      --  Right_Opnd (Node3)
      --  Actions (List1-Sem)
      --  plus fields for expression

      ---------------------------
      -- 4.5  Membership Tests --
      ---------------------------

      --  RELATION ::=
      --    SIMPLE_EXPRESSION [not] in RANGE
      --  | SIMPLE_EXPRESSION [not] in SUBTYPE_MARK

      --  N_In
      --  Sloc points to IN
      --  Left_Opnd (Node2)
      --  Right_Opnd (Node3)
      --  plus fields for expression

      --  N_Not_In
      --  Sloc points to NOT of NOT IN
      --  Left_Opnd (Node2)
      --  Right_Opnd (Node3)
      --  plus fields for expression

      --------------------
      -- 4.5  Operators --
      --------------------

      --  LOGICAL_OPERATOR             ::=  and | or  | xor

      --  RELATIONAL_OPERATOR          ::=  =   | /=  | <   | <= | > | >=

      --  BINARY_ADDING_OPERATOR       ::=  +   |  -  | &

      --  UNARY_ADDING_OPERATOR        ::=  +   |  -

      --  MULTIPLYING_OPERATOR         ::=  *   |  /  | mod | rem

      --  HIGHEST_PRECEDENCE_OPERATOR  ::=  **  | abs | not

      --  Sprint syntax if Treat_Fixed_As_Integer is set:

      --     x #* y
      --     x #/ y
      --     x #mod y
      --     x #rem y

      --  Note: For the operators * / mod rem with fixed-point operands, Gigi
      --  will only be given nodes with the Treat_Fixed_As_Integer flag set.
      --  All handling of smalls for multiplication and division is handled
      --  by the front end (mod and rem result only from expansion). Gigi
      --  thus never needs to worry about small values (for other operators
      --  operating on fixed-point, e.g. addition, the small value does not
      --  have any semantic effect anyway, these are always integer operations.

      --  N_Op_And
      --  Sloc points to AND
      --  Do_Length_Check (Flag4-Sem)
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Or
      --  Sloc points to OR
      --  Do_Length_Check (Flag4-Sem)
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Xor
      --  Sloc points to XOR
      --  Do_Length_Check (Flag4-Sem)
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Eq
      --  Sloc points to =
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Ne
      --  Sloc points to /=
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Lt
      --  Sloc points to <
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Le
      --  Sloc points to <=
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Gt
      --  Sloc points to >
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Ge
      --  Sloc points to >=
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Add
      --  Sloc points to + (binary)
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Subtract
      --  Sloc points to - (binary)
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Concat
      --  Sloc points to &
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Multiply
      --  Sloc points to *
      --  Treat_Fixed_As_Integer (Flag14-Sem)
      --  Rounded_Result (Flag12-Sem)
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Divide
      --  Sloc points to /
      --  Treat_Fixed_As_Integer (Flag14-Sem)
      --  Do_Division_Check (Flag3-Sem)
      --  Rounded_Result (Flag12-Sem)
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Mod
      --  Sloc points to MOD
      --  Treat_Fixed_As_Integer (Flag14-Sem)
      --  Do_Division_Check (Flag3-Sem)
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Rem
      --  Sloc points to REM
      --  Treat_Fixed_As_Integer (Flag14-Sem)
      --  Do_Division_Check (Flag3-Sem)
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Expon
      --  Sloc points to **
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Plus
      --  Sloc points to + (unary)
      --  plus fields for unary operator
      --  plus fields for expression

      --  N_Op_Minus
      --  Sloc points to - (unary)
      --  plus fields for unary operator
      --  plus fields for expression

      --  N_Op_Abs
      --  Sloc points to ABS
      --  plus fields for unary operator
      --  plus fields for expression

      --  N_Op_Not
      --  Sloc points to NOT
      --  plus fields for unary operator
      --  plus fields for expression

      --  See also shift operators in section B.2

      --  Note on fixed-point operations passed to Gigi: For adding operators,
      --  the semantics is to treat these simply as integer operations, with
      --  the small values being ignored (the bounds are already stored in
      --  units of small, so that constraint checking works as usual). For the
      --  case of multiply/divide/rem/mod operations, Gigi will only see fixed
      --  point operands if the Treat_Fixed_As_Integer flag is set and will
      --  thus treat these nodes in identical manner, ignoring small values.

      --------------------------
      -- 4.6  Type Conversion --
      --------------------------

      --  TYPE_CONVERSION ::=
      --    SUBTYPE_MARK (EXPRESSION) | SUBTYPE_MARK (NAME)

      --  In the (NAME) case, the name is stored as the expression

      --  Note: the parser never generates a type conversion node, since it
      --  looks like an indexed component which is generated by preference.
      --  The semantic pass must correct this misidentification.

      --  Gigi handles conversions that involve no change in the root type,
      --  and also all conversions from integer to floating-point types.
      --  Conversions from floating-point to integer are only handled in
      --  the case where Float_Truncate flag set. Other conversions from
      --  floating-point to integer (involving rounding) and all conversions
      --  involving fixed-point types are handled by the expander.

      --  Sprint syntax if Float_Truncate set: X^(Y)
      --  Sprint syntax if Conversion_OK set X?(Y)
      --  Sprint syntax if both flags set X?^(Y)

      --  Note: If either the operand or result type is fixed-point, Gigi will
      --  only see a type conversion node with Treat_Fixed_As_Integer set. The
      --  front end takes care of all handling of small's for conversions.

      --  N_Type_Conversion
      --  Sloc points to first token of subtype mark
      --  Subtype_Mark (Node4)
      --  Expression (Node3)
      --  Do_Overflow_Check (Flag17-Sem)
      --  Do_Tag_Check (Flag3-Sem)
      --  Do_Length_Check (Flag4-Sem)
      --  Float_Truncate (Flag11-Sem)
      --  Rounded_Result (Flag12-Sem)
      --  Conversion_OK (Flag14-Sem)
      --  plus fields for expression

      --  Note: if a range check is required, then the Do_Range_Check flag
      --  is set in the Expression with the check being done against the
      --  target type range (after the base type conversion, if any).

      -------------------------------
      -- 4.7  Qualified Expression --
      -------------------------------

      --  QUALIFIED_EXPRESSION ::=
      --    SUBTYPE_MARK ' (EXPRESSION) | SUBTYPE_MARK ' AGGREGATE

      --  Note: the parentheses in the (EXPRESSION) case are deemed to enclose
      --  the expression, so the Expression field of this node always points
      --  to a parenthesized expression in this case (i.e. Paren_Count will
      --  always be non-zero for the referenced expression if is is not an
      --  aggregate).

      --  N_Qualified_Expression
      --  Sloc points to apostrophe
      --  Subtype_Mark (Node4)
      --  Expression (Node3) expression or aggregate
      --  plus fields for expression

      --------------------
      -- 4.8  Allocator --
      --------------------

      --  ALLOCATOR ::=
      --    new SUBTYPE_INDICATION | new QUALIFIED_EXPRESSION

      --  Sprint syntax (when storage pool present)
      --    new xxx (storage_pool = pool)

      --  N_Allocator
      --  Sloc points to NEW
      --  Expression (Node3) subtype indication or qualified expression
      --  Storage_Pool (Node1-Sem)
      --  Procedure_To_Call (Node4-Sem)
      --  Do_Storage_Check (Flag17-Sem)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  plus fields for expression

      ---------------------------------
      -- 5.1  Sequence Of Statements --
      ---------------------------------

      --  SEQUENCE_OF_STATEMENTS ::= STATEMENT {STATEMENT}

      --  Note: Although the parser will not accept a declaration as a
      --  statement, the semantic analyzer may insert declarations (e.g.
      --  declarations of implicit types needed for execution of other
      --  statements) into a sequence of statements, so the code genmerator
      --  should be prepared to accept a declaration where a statement is
      --  expected. Note also that pragmas can appear as statements.

      --------------------
      -- 5.1  Statement --
      --------------------

      --  STATEMENT ::=
      --    {LABEL} SIMPLE_STATEMENT | {LABEL} COMPOUND_STATEMENT

      --  There is no explicit node in the tree for a statement. Instead, the
      --  individual statement appears directly. Labels are treated  as a
      --  kind of statement, i.e. they are linked into a statement list at
      --  the point they appear, so the labeled statement appears following
      --  the label or labels in the statement list.

      ---------------------------
      -- 5.1  Simple Statement --
      ---------------------------

      --  SIMPLE_STATEMENT ::=      NULL_STATEMENT
      --  | ASSIGNMENT_STATEMENT  | EXIT_STATEMENT
      --  | GOTO_STATEMENT        | PROCEDURE_CALL_STATEMENT
      --  | RETURN_STATEMENT      | ENTRY_CALL_STATEMENT
      --  | REQUEUE_STATEMENT     | DELAY_STATEMENT
      --  | ABORT_STATEMENT       | RAISE_STATEMENT
      --  | CODE_STATEMENT

      -----------------------------
      -- 5.1  Compound Statement --
      -----------------------------

      --  COMPOUND_STATEMENT ::=
      --    IF_STATEMENT         | CASE_STATEMENT
      --  | LOOP_STATEMENT       | BLOCK_STATEMENT
      --  | ACCEPT_STATEMENT     | SELECT_STATEMENT

      -------------------------
      -- 5.1  Null Statement --
      -------------------------

      --  NULL_STATEMENT ::= null;

      --  N_Null_Statement
      --  Sloc points to NULL

      ----------------
      -- 5.1  Label --
      ----------------

      --  LABEL ::= <<label_STATEMENT_IDENTIFIER>>

      --  Note that the occurrence of a label is not a defining identifier,
      --  but rather a referencing occurrence. The defining occurrence is
      --  in the implicit label declaration which occurs in the innermost
      --  enclosing block.

      --  N_Label
      --  Sloc points to <<
      --  Identifier (Node1) direct name of statement identifier

      -------------------------------
      -- 5.1  Statement Identifier --
      -------------------------------

      --  STATEMENT_INDENTIFIER ::= DIRECT_NAME

      --  The IDENTIFIER of a STATEMENT_IDENTIFIER shall be an identifier
      --  (not an OPERATOR_SYMBOL)

      -------------------------------
      -- 5.2  Assignment Statement --
      -------------------------------

      --  ASSIGNMENT_STATEMENT ::=
      --    variable_NAME := EXPRESSION;

      --  N_Assignment_Statement
      --  Sloc points to :=
      --  Name (Node2)
      --  Expression (Node3)
      --  Do_Tag_Check (Flag3-Sem)
      --  Do_Length_Check (Flag4-Sem)
      --  Forwards_OK (Flag5-Sem)
      --  Backwards_OK (Flag6-Sem)

      --  Note: if a range check is required, then the Do_Range_Check flag
      --  is set in the Expression (right hand side), with the check being
      --  done against the type of the Name (left hand side).

      -----------------------
      -- 5.3  If Statement --
      -----------------------

      --  IF_STATEMENT ::=
      --    if CONDITION then
      --      SEQUENCE_OF_STATEMENTS
      --    {elsif CONDITION then
      --      SEQUENCE_OF_STATEMENTS}
      --    [else
      --      SEQUENCE_OF_STATEMENTS]
      --    end if;

      --  N_If_Statement
      --  Sloc points to IF
      --  Condition (Node5)
      --  Then_Statements (List2)
      --  Elsif_Parts (List3) (set to No_List if none present)
      --  Else_Statements (List4) (set to No_List if no else part present)

      --  N_Elsif_Part
      --  Sloc points to ELSIF
      --  Condition (Node5)
      --  Then_Statements (List2)
      --  Condition_Actions (List3-Sem)

      --------------------
      -- 5.3  Condition --
      --------------------

      --  CONDITION ::= boolean_EXPRESSION

      -------------------------
      -- 5.4  Case Statement --
      -------------------------

      --  CASE_STATEMENT ::=
      --    case EXPRESSION is
      --      CASE_STATEMENT_ALTERNATIVE
      --      {CASE_STATEMENT_ALTERNATIVE}
      --    end case;

      --  N_Case_Statement
      --  Sloc points to CASE
      --  Expression (Node3)
      --  Alternatives (List4)

      -------------------------------------
      -- 5.4  Case Statement Alternative --
      -------------------------------------

      --  CASE_STATEMENT_ALTERNATIVE ::=
      --    when DISCRETE_CHOICE_LIST =>
      --      SEQUENCE_OF_STATEMENTS

      --  N_Case_Statement_Alternative
      --  Sloc points to WHEN
      --  Discrete_Choices (List4)
      --  Statements (List3)

      -------------------------
      -- 5.5  Loop Statement --
      -------------------------

      --  LOOP_STATEMENT ::=
      --    [loop_STATEMENT_IDENTIFIER :]
      --      [ITERATION_SCHEME] loop
      --        SEQUENCE_OF_STATEMENTS
      --      end loop [loop_IDENTIFIER];

      --  Note: The occurrence of a loop label is not a defining identifier
      --  but rather a referencing occurrence. The defining occurrence is in
      --  the implicit label declaration which occurs in the innermost
      --  enclosing block.

      --  Note: there is always a loop statement identifier present in
      --  the tree, even if none was given in the source. In the case where
      --  no loop identifier is given in the source, the parser creates
      --  a name of the form _Loop_n, where n is a decimal integer (the
      --  two underlines ensure that the loop names created in this manner
      --  do not conflict with any user defined identifiers), and the flag
      --  Has_Created_Identifier is set to True. The only exception to the
      --  rule that all loop statement nodes have identifiers occurs for
      --  loops constructed by the expander, and the semantic analyzer will
      --  create and supply dummy loop identifiers in these cases.

      --  N_Loop_Statement
      --  Sloc points to LOOP
      --  Identifier (Node1) loop identifier (set to Empty if no identifier)
      --  Iteration_Scheme (Node2) (set to Empty if no iteration scheme)
      --  Statements (List3)
      --  Has_Created_Identifier (Flag1)

      --------------------------
      -- 5.5 Iteration Scheme --
      --------------------------

      --  ITERATION_SCHEME ::=
      --    while CONDITION | for LOOP_PARAMETER_SPECIFICATION

      --  N_Iteration_Scheme
      --  Sloc points to WHILE or FOR
      --  Condition (Node5) (set to Empty if for case)
      --  Condition_Actions (List3-Sem)
      --  Loop_Parameter_Specification (Node1) (set to Empty if while case)

      ---------------------------------------
      -- 5.5  Loop parameter specification --
      ---------------------------------------

      --  LOOP_PARAMETER_SPECIFICATION ::=
      --    DEFINING_IDENTIFIER in [reverse] DISCRETE_SUBTYPE_DEFINITION

      --  N_Loop_Parameter_Specification
      --  Sloc points to first identifier
      --  Defining_Identifier (Node1)
      --  Reverse_Present (Flag1)
      --  Discrete_Subtype_Definition (Node4)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      --------------------------
      -- 5.6  Block Statement --
      --------------------------

      --  BLOCK_STATEMENT ::=
      --    [block_STATEMENT_IDENTIFIER:]
      --      [declare
      --        DECLARATIVE_PART]
      --      begin
      --        HANDLED_SEQUENCE_OF_STATEMENTS
      --      end [block_IDENTIFIER];

      --  Note that the occurrence of a block identifier is not a defining
      --  identifier, but rather a referencing occurrence. The defining
      --  occurrence is in the implicit label declaration which occurs in
      --  the innermost enclosing block.

      --  Note: there is always a block statement identifier present in
      --  the tree, even if none was given in the source. In the case where
      --  no block identifier is given in the source, the parser creates
      --  a name of the form _Block_n, where n is a decimal integer (the
      --  two underlines ensure that the block names created in this manner
      --  do not conflict with any user defined identifiers), and the flag
      --  Has_Created_Identifier is set to True. The only exception to the
      --  rule that all loop statement nodes have identifiers occurs for
      --  blocks constructed by the expander, and the semantic analyzer
      --  creates and supplies dummy names for the blocks).

      --  N_Block_Statement
      --  Sloc points to DECLARE or BEGIN
      --  Identifier (Node1) block direct name (set to Empty if not present)
      --  Declarations (List3) (set to No_List if no DECLARE part)
      --  Handled_Statement_Sequence (Node4)
      --  Is_Task_Master (Flag5-Sem)
      --  Activation_Chain_Entity (Node2-Sem)
      --  Has_Created_Identifier (Flag1)

      -------------------------
      -- 5.7  Exit Statement --
      -------------------------

      --  EXIT_STATEMENT ::= exit [loop_NAME] [when CONDITION];

      --  N_Exit_Statement
      --  Sloc points to EXIT
      --  Name (Node2) (set to Empty if no loop name present)
      --  Condition (Node5) (set to Empty if no when part present)

      -------------------------
      -- 5.9  Goto Statement --
      -------------------------

      --  GOTO_STATEMENT ::= goto label_NAME;

      --  N_Goto_Statement
      --  Sloc points to GOTO
      --  Name (Node2)

      ---------------------------------
      -- 6.1  Subprogram Declaration --
      ---------------------------------

      --  SUBPROGRAM_DECLARATION ::= SUBPROGRAM_SPECIFICATION;

      --  N_Subprogram_Declaration
      --  Sloc points to FUNCTION or PROCEDURE
      --  Specification (Node1)
      --  Corresponding_Body (Node5-Sem)
      --  Parent_Spec (Node4-Sem)

      ------------------------------------------
      -- 6.1  Abstract Subprogram Declaration --
      ------------------------------------------

      --  ABSTRACT_SUBPROGRAM_DECLARATION ::=
      --    SUBPROGRAM_SPECIFICATION is abstract;

      --  N_Abstract_Subprogram_Declaration
      --  Sloc points to ABSTRACT
      --  Specification (Node1)

      -----------------------------------
      -- 6.1  Subprogram Specification --
      -----------------------------------

      --  SUBPROGRAM_SPECIFICATION ::=
      --    procedure DEFINING_PROGRAM_UNIT_NAME PARAMETER_PROFILE
      --  | function DEFINING_DESIGNATOR PARAMETER_AND_RESULT_PROFILE

      --  Note: there are no separate nodes for the profiles, instead the
      --  information appears directly in the following nodes.

      --  N_Function_Specification
      --  Sloc points to FUNCTION
      --  Defining_Unit_Name (Node1) (the designator)
      --  Parameter_Specifications (List3) (set to No_List if no formal part)
      --  Subtype_Mark (Node4) for return type
      --  Generic_Parent (Node5-Sem)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      --  N_Procedure_Specification
      --  Sloc points to PROCEDURE
      --  Defining_Unit_Name (Node1)
      --  Parameter_Specifications (List3) (set to No_List if no formal part)
      --  Generic_Parent (Node5-Sem)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      ---------------------
      -- 6.1  Designator --
      ---------------------

      --  DESIGNATOR ::=
      --    [PARENT_UNIT_NAME .] IDENTIFIER | OPERATOR_SYMBOL

      --  Designators that are simply identifiers or operator symbols appear
      --  directly in the tree in this form. The following node is used only
      --  in the case where the designator has a parent unit name component.

      --  N_Designator
      --  Sloc points to period
      --  Name (Node2) holds the parent unit name. Note that this is always
      --   non-Empty, since this node is only used for the case where a
      --   parent library unit package name is present.
      --  Identifier (Node1)

      ------------------------------
      -- 6.1  Defining Designator --
      ------------------------------

      --  DEFINING_DESIGNATOR ::=
      --    DEFINING_PROGRAM_UNIT_NAME | DEFINING_OPERATOR_SYMBOL

      -------------------------------------
      -- 6.1  Defining Program Unit Name --
      -------------------------------------

      --  DEFINING_PROGRAM_UNIT_NAME ::=
      --    [PARENT_UNIT_NAME .] DEFINING_IDENTIFIER

      --  The parent unit name is present only in the case of a child unit
      --  name (permissible only for Ada 95 for a library level unit, i.e.
      --  a unit at scope level one). If no such name is present, the defining
      --  program unit name is represented simply as the defining identifier.
      --  In the child unit case, the following node is used to represent the
      --  child unit name.

      --  N_Defining_Program_Unit_Name
      --  Sloc points to period
      --  Name (Node2) holds the parent unit name. Note that this is always
      --   non-Empty, since this node is only used for the case where a
      --   parent unit name is present.
      --  Defining_Identifier (Node1)

      --------------------------
      -- 6.1  Operator Symbol --
      --------------------------

      --  OPERATOR_SYMBOL ::= STRING_LITERAL

      --  Note: the fields of the N_Operator_Symbol node are laid out to
      --  match the corresponding fields of an N_Character_Literal node. This
      --  allows easy conversion of the operator symbol node into a character
      --  literal node in the case where a string constant of the form of an
      --  operator symbol is scanned out as such, but turns out semantically
      --  to be a string literal that is not an operator. For details see
      --  Sinfo.CN.Change_Operator_Symbol_To_String_Literal.

      --  N_Operator_Symbol
      --  Sloc points to literal
      --  Chars (Name1) contains the Name_Id for the operator symbol
      --  Strval (Str3) Id of string value. This is used if the operator
      --   symbol turns out to be a normal string after all.
      --  Entity (Node4-Sem)
      --  Has_Private_View (Flag11-Sem) set in generic units.
      --  Etype (Node5-Sem)

      -----------------------------------
      -- 6.1  Defining Operator Symbol --
      -----------------------------------

      --  DEFINING_OPERATOR_SYMBOL ::= OPERATOR_SYMBOL

      --  A defining operator symbol is an entity, which has additional
      --  fields depending on the setting of the Ekind field. These
      --  additional fields are defined (and access subprograms declared)
      --  in package Entity_Info.

      --  Note: N_Defining_Operator_Symbol is an extended node whose fields
      --  are deliberate layed out to match the layout of fields in an ordinary
      --  N_Operator_Symbol node allowing for easy alteration of an operator
      --  symbol node into a defining operator symbol node. For details, see
      --  Sinfo.CN.Change_Operator_Symbol_To_Defining_Operator_Symbol.

      --  N_Defining_Operator_Symbol
      --  Sloc points to literal
      --  Chars (Name1) contains the Name_Id for the operator symbol
      --  Next_Entity (Node2-Sem)
      --  Scope (Node3-Sem)
      --  Homonym (Node4-Sem)
      --  Etype (Node5-Sem)

      ----------------------------
      -- 6.1  Parameter Profile --
      ----------------------------

      --  PARAMETER_PROFILE ::= [FORMAL_PART]

      ---------------------------------------
      -- 6.1  Parameter and Result Profile --
      ---------------------------------------

      --  PARAMETER_AND_RESULT_PROFILE ::= [FORMAL_PART] return SUBTYPE_MARK

      --  There is no explicit node in the tree for a parameter and result
      --  profile. Instead the information appears directly in the parent.

      ----------------------
      -- 6.1  Formal part --
      ----------------------

      --  FORMAL_PART ::=
      --    (PARAMETER_SPECIFICATION {; PARAMETER_SPECIFICATION})

      ----------------------------------
      -- 6.1  Parameter specification --
      ----------------------------------

      --  PARAMETER_SPECIFICATION ::=
      --    DEFINING_IDENTIFIER_LIST : MODE SUBTYPE_MARK
      --      [:= DEFAULT_EXPRESSION]
      --  | DEFINING_IDENTIFIER_LIST : ACCESS_DEFINITION
      --      [:= DEFAULT_EXPRESSION]

      --  Although the syntax allows multiple identifiers in the list, the
      --  semantics is as though successive specifications were given with
      --  identical type definition and expression components. To simplify
      --  semantic processing, the parser represents a multiple declaration
      --  case as a sequence of single Specifications, using the More_Ids and
      --  Prev_Ids flags to preserve the original source form as described
      --  in the section on "Handling of Defining Identifier Lists".

      --  N_Parameter_Specification
      --  Sloc points to first identifier
      --  Defining_Identifier (Node1)
      --  In_Present (Flag1)
      --  Out_Present (Flag17)
      --  Parameter_Type (Node2) subtype mark or access definition
      --  Expression (Node3) (set to Empty if no initialization present)
      --  Do_Accessibility_Check (Flag3-Sem)
      --  More_Ids (Flag5) (set to False if no more identifiers in list)
      --  Prev_Ids (Flag6) (set to False if no previous identifiers in list)

      ---------------
      -- 6.1  Mode --
      ---------------

      --  MODE ::= [in] | in out | out

      --  There is no explicit node in the tree for the Mode. Instead the
      --  In_Present and Out_Present flags are set in the parent node to
      --  record the presence of keywords specifying the mode.

      --------------------------
      -- 6.3  Subprogram Body --
      --------------------------

      --  SUBPROGRAM_BODY ::=
      --    SUBPROGRAM_SPECIFICATION is
      --      DECLARATIVE_PART
      --    begin
      --      HANDLED_SEQUENCE_OF_STATEMENTS
      --    end [DESIGNATOR];

      --  N_Subprogram_Body
      --  Sloc points to FUNCTION or PROCEDURE
      --  Specification (Node1)
      --  Declarations (List3)
      --  Handled_Statement_Sequence (Node4)
      --  Bad_Is_Detected (Flag1) used only by parser
      --  Corresponding_Spec (Node5-Sem)
      --  Acts_As_Spec (Flag4-Sem)
      --  Do_Storage_Check (Flag17-Sem)
      --  Is_Task_Master (Flag5-Sem)
      --  Activation_Chain_Entity (Node2-Sem)
      --  Has_Priority_Pragma (Flag6-Sem)

      -----------------------------------
      -- 6.4  Procedure Call Statement --
      -----------------------------------

      --  PROCEDURE_CALL_STATEMENT ::=
      --    procedure_NAME; | procedure_PREFIX ACTUAL_PARAMETER_PART;

      --  Note: the reason that a procedure call has expression fields is
      --  that it semantically resembles an expression, e.g. overloading is
      --  allowed and a type is concocted for semantic processing purposes.
      --  Certain of these fields, such as Parens are not relevant, but it
      --  is easier to just supply all of them together!

      --  N_Procedure_Call_Statement
      --  Sloc points to first token of name or prefix
      --  Name (Node2) stores name or prefix
      --  Parameter_Associations (List3) (set to No_List if no
      --   actual parameter part)
      --  First_Named_Actual (Node4-Sem)
      --  Controlling_Argument (Node1-Sem) controlling tag (set to Empty if
      --   non-dispatching call)
      --  Do_Tag_Check (Flag3-Sem)
      --  plus fields for expression

      --  If any IN parameter requires a range check, then the corresponding
      --  argument expression has the Do_Range_Check flag set, and the range
      --  check is done against the formal type. Note that this argument
      --  expression may appear directly in the Parameter_Associations list,
      --  or may be a descendent of an N_Parameter_Association node that
      --  appears in this list.

      ------------------------
      -- 6.4  Function Call --
      ------------------------

      --  FUNCTION_CALL ::=
      --    function_NAME | function_PREFIX ACTUAL_PARAMETER_PART

      --  Note: the parser may generate an indexed component node or simply
      --  a name node instead of a function call node. The semantic pass must
      --  correct this misidentification.

      --  N_Function_Call
      --  Sloc points to first token of name or prefix
      --  Name (Node2) stores name or prefix
      --  Parameter_Associations (List3) (set to No_List if no
      --   actual parameter part)
      --  First_Named_Actual (Node4-Sem)
      --  Controlling_Argument (Node1-Sem) controlling tag (set to Empty if
      --   non-dispatching call)
      --  Do_Tag_Check (Flag3-Sem)
      --  plus fields for expression

      --------------------------------
      -- 6.4  Actual Parameter Part --
      --------------------------------

      --  ACTUAL_PARAMETER_PART ::=
      --    (PARAMETER_ASSOCIATION {,PARAMETER_ASSOCIATION})

      --------------------------------
      -- 6.4  Parameter Association --
      --------------------------------

      --  PARAMETER_ASSOCIATION ::=
      --    [formal_parameter_SELECTOR_NAME =>] EXPLICIT_ACTUAL_PARAMETER

      --  Note: the N_Parameter_Association node is built only if a formal
      --  parameter selector name is present, otherwise the parameter
      --  association appears in the tree simply as the node for the
      --  explicit actual parameter.

      --  N_Parameter_Association
      --  Sloc points to formal parameter
      --  Selector_Name (Node2) (always non-Empty, since this node is
      --   only used if a formal parameter selector name is present)
      --  Explicit_Actual_Parameter (Node3)
      --  Next_Named_Actual (Node4-Sem)

      ---------------------------
      -- 6.4  Actual Parameter --
      ---------------------------

      --  EXPLICIT_ACTUAL_PARAMETER ::= EXPRESSION | variable_NAME

      ---------------------------
      -- 6.5  Return Statement --
      ---------------------------

      --  RETURN_STATEMENT ::= return [EXPRESSION];

      --  N_Return_Statement
      --  Sloc points to RETURN
      --  Expression (Node3) (set to Empty if no expression present)
      --  Storage_Pool (Node1-Sem)
      --  Procedure_To_Call (Node4-Sem)
      --  Do_Tag_Check (Flag3-Sem)
      --  Return_Type (Node2-Sem)

      --  Note: if a range check is required, then Do_Range_Check is set
      --  on the Expression. The range check is against Return_Type.

      ------------------------------
      -- 7.1  Package Declaration --
      ------------------------------

      --  PACKAGE_DECLARATION ::= PACKAGE_SPECIFICATION;

      --  Note: the activation chain entity for a package spec is used for
      --  all tasks declared in the package spec, or in the package body.

      --  N_Package_Declaration
      --  Sloc points to PACKAGE
      --  Specification (Node1)
      --  Corresponding_Body (Node5-Sem)
      --  Parent_Spec (Node4-Sem)
      --  Activation_Chain_Entity (Node2-Sem)

      --------------------------------
      -- 7.1  Package Specification --
      --------------------------------

      --  PACKAGE_SPECIFICATION ::=
      --    package DEFINING_PROGRAM_UNIT_NAME is
      --      {BASIC_DECLARATIVE_ITEM}
      --    [private
      --      {BASIC_DECLARATIVE_ITEM}]
      --    end [[PARENT_UNIT_NAME .] IDENTIFIER]

      --  N_Package_Specification
      --  Sloc points to PACKAGE
      --  Defining_Unit_Name (Node1)
      --  Visible_Declarations (List2)
      --  Private_Declarations (List4) (set to No_List if no private
      --   part present)
      --  Generic_Parent (Node5-Sem)

      -----------------------
      -- 7.1  Package Body --
      -----------------------

      --  PACKAGE_BODY ::=
      --    package body DEFINING_PROGRAM_UNIT_NAME is
      --      DECLARATIVE_PART
      --    [begin
      --      HANDLED_SEQUENCE_OF_STATEMENTS]
      --    end [[PARENT_UNIT_NAME .] IDENTIFIER];

      --  N_Package_Body
      --  Sloc points to PACKAGE
      --  Defining_Unit_Name (Node1)
      --  Declarations (List3)
      --  Handled_Statement_Sequence (Node4) (set to Empty if not present)
      --  Corresponding_Spec (Node5-Sem)

      -----------------------------------
      -- 7.4  Private Type Declaration --
      -----------------------------------

      --  PRIVATE_TYPE_DECLARATION ::=
      --    type DEFINING_IDENTIFIER [DISCRIMINANT_PART]
      --      is [[abstract] tagged] [limited] private;

      --  Note: TAGGED is not permitted in Ada 83 mode

      --  N_Private_Type_Declaration
      --  Sloc points to TYPE
      --  Defining_Identifier (Node1)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  Discriminant_Specifications (List4) (set to No_List if no
      --   discriminant part)
      --  Unknown_Discriminants_Present (Flag3) set if (<>) discriminant
      --  Abstract_Present (Flag4)
      --  Tagged_Present (Flag1)
      --  Limited_Present (Flag17)

      ----------------------------------------
      -- 7.4  Private Extension Declaration --
      ----------------------------------------

      --  PRIVATE_EXTENSION_DECLARATION ::=
      --    type DEFINING_IDENTIFIER [DISCRIMINANT_PART] is
      --      [abstract] new ancestor_SUBTYPE_INDICATION with private;

      --  Note: private extension declarations are not allowed in Ada 83 mode

      --  N_Private_Extension_Declaration
      --  Sloc points to TYPE
      --  Defining_Identifier (Node1)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  Discriminant_Specifications (List4) (set to No_List if no
      --   discriminant part)
      --  Unknown_Discriminants_Present (Flag3) set if (<>) discriminant
      --  Abstract_Present (Flag4)
      --  Subtype_Indication (Node5)

      ---------------------
      -- 8.4  Use Clause --
      ---------------------

      --  USE_CLAUSE ::= USE_PACKAGE_CLAUSE | USE_TYPE_CLAUSE

      -----------------------------
      -- 8.4  Use Package Clause --
      -----------------------------

      --  USE_PACKAGE_CLAUSE ::= use package_NAME {, package_NAME};

      --  N_Use_Package_Clause
      --  Sloc points to USE
      --  Names (List2)
      --  Next_Use_Clause (Node3-Sem)

      --------------------------
      -- 8.4  Use Type Clause --
      --------------------------

      --  USE_TYPE_CLAUSE ::= use type SUBTYPE_MARK {, SUBTYPE_MARK};

      --  Note: use type clause is not permitted in Ada 83 mode

      --  N_Use_Type_Clause
      --  Sloc points to USE
      --  Subtype_Marks (List2)
      --  Next_Use_Clause (Node3-Sem)

      -------------------------------
      -- 8.5  Renaming Declaration --
      -------------------------------

      --  RENAMING_DECLARATION ::=
      --    OBJECT_RENAMING_DECLARATION
      --  | EXCEPTION_RENAMING_DECLARATION
      --  | PACKAGE_RENAMING_DECLARATION
      --  | SUBPROGRAM_RENAMING_DECLARATION
      --  | GENERIC_RENAMING_DECLARATION

      --------------------------------------
      -- 8.5  Object Renaming Declaration --
      --------------------------------------

      --  OBJECT_RENAMING_DECLARATION ::=
      --    DEFINING_IDENTIFIER : SUBTYPE_MARK renames object_NAME;

      --  N_Object_Renaming_Declaration
      --  Sloc points to first identifier
      --  Defining_Identifier (Node1)
      --  Subtype_Mark (Node4)
      --  Name (Node2)

      -----------------------------------------
      -- 8.5  Exception Renaming Declaration --
      -----------------------------------------

      --  EXCEPTION_RENAMING_DECLARATION ::=
      --    DEFINING_IDENTIFIER : exception renames exception_NAME;

      --  N_Exception_Renaming_Declaration
      --  Sloc points to first identifier
      --  Defining_Identifier (Node1)
      --  Name (Node2)

      ---------------------------------------
      -- 8.5  Package Renaming Declaration --
      ---------------------------------------

      --  PACKAGE_RENAMING_DECLARATION ::=
      --    package DEFINING_PROGRAM_UNIT_NAME renames package_NAME;

      --  N_Package_Renaming_Declaration
      --  Sloc points to PACKAGE
      --  Defining_Unit_Name (Node1)
      --  Name (Node2)
      --  Parent_Spec (Node4-Sem)

      ------------------------------------------
      -- 8.5  Subprogram Renaming Declaration --
      ------------------------------------------

      --  SUBPROGRAM_RENAMING_DECLARATION ::=
      --    SUBPROGRAM_SPECIFICATION renames callable_entity_NAME;

      --  N_Subprogram_Renaming_Declaration
      --  Sloc points to RENAMES
      --  Specification (Node1)
      --  Name (Node2)
      --  Parent_Spec (Node4-Sem)
      --  Corresponding_Spec (Node5-Sem)

      -----------------------------------------
      -- 8.5.5  Generic Renaming Declaration --
      -----------------------------------------

      --  GENERIC_RENAMING_DECLARATION ::=
      --    generic package DEFINING_PROGRAM_UNIT_NAME
      --      renames generic_package_NAME
      --  | generic procedure DEFINING_PROGRAM_UNIT_NAME
      --      renames generic_procedure_NAME
      --  | generic function DEFINING_PROGRAM_UNIT_NAME
      --      renames generic_function_NAME

      --  N_Generic_Package_Renaming_Declaration
      --  Sloc points to GENERIC
      --  Defining_Unit_Name (Node1)
      --  Name (Node2)
      --  Parent_Spec (Node4-Sem)

      --  N_Generic_Procedure_Renaming_Declaration
      --  Sloc points to GENERIC
      --  Defining_Unit_Name (Node1)
      --  Name (Node2)
      --  Parent_Spec (Node4-Sem)

      --  N_Generic_Function_Renaming_Declaration
      --  Sloc points to GENERIC
      --  Defining_Unit_Name (Node1)
      --  Name (Node2)
      --  Parent_Spec (Node4-Sem)

      --------------------------------
      -- 9.1  Task Type Declaration --
      --------------------------------

      --  TASK_TYPE_DECLARATION ::=
      --    task type DEFINING_IDENTIFIER [KNOWN_DISCRIMINANT_PART]
      --      [is TASK_DEFINITITION];

      --  N_Task_Type_Declaration
      --  Sloc points to TASK
      --  Defining_Identifier (Node1)
      --  Discriminant_Specifications (List4) (set to No_List if no
      --   discriminant part)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  Task_Definition (Node3) (set to Empty if not present)
      --  Corresponding_Body (Node5-Sem)

      ----------------------------------
      -- 9.1  Single Task Declaration --
      ----------------------------------

      --  SINGLE_TASK_DECLARATION ::=
      --    task DEFINING_IDENTIFIER [is TASK_DEFINITION];

      --  N_Single_Task_Declaration
      --  Sloc points to TASK
      --  Defining_Identifier (Node1)
      --  Task_Definition (Node3) (set to Empty if not present)

      --------------------------
      -- 9.1  Task Definition --
      --------------------------

      --  TASK_DEFINITION ::=
      --      {TASK_ITEM}
      --    [private
      --      {TASK_ITEM}]
      --    end [task_IDENTIFIER]

      --  Note: as a result of semantic analysis, the list of task items can
      --  include implicit type declarations resulting from entry families.

      --  N_Task_Definition
      --  Sloc points to first token of task definition
      --  Visible_Declarations (List2)
      --  Private_Declarations (List4) (set to No_List if no private part)
      --  Has_Priority_Pragma (Flag6-Sem)
      --  Has_Storage_Size_Pragma (Flag5-Sem)

      --------------------
      -- 9.1  Task Item --
      --------------------

      --  TASK_ITEM ::= ENTRY_DECLARATION | REPRESENTATION_CLAUSE

      --------------------
      -- 9.1  Task Body --
      --------------------

      --  TASK_BODY ::=
      --    task body task_DEFINING_IDENTIFIER is
      --      DECLARATIVE_PART
      --    begin
      --      HANDLED_SEQUENCE_OF_STATEMENTS
      --    end [task_IDENTIFIER];

      --  Gigi restriction: This node never appears.

      --  N_Task_Body
      --  Sloc points to TASK
      --  Defining_Identifier (Node1)
      --  Declarations (List3)
      --  Handled_Statement_Sequence (Node4)
      --  Is_Task_Master (Flag5-Sem)
      --  Activation_Chain_Entity (Node2-Sem)
      --  Corresponding_Spec (Node5-Sem)

      -------------------------------------
      -- 9.4  Protected Type Declaration --
      -------------------------------------

      --  PROTECTED_TYPE_DECLARATION ::=
      --    protected type DEFINING_IDENTIFIER [KNOWN_DISCRIMINANT_PART]
      --      is PROTECTED_DEFINITION;

      --  Note: protected type declarations are not permitted in Ada 83 mode

      --  N_Protected_Type_Declaration
      --  Sloc points to PROTECTED
      --  Defining_Identifier (Node1)
      --  Discriminant_Specifications (List4) (set to No_List if no
      --   discriminant part)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  Protected_Definition (Node3)
      --  Corresponding_Body (Node5-Sem)

      ---------------------------------------
      -- 9.4  Single Protected Declaration --
      ---------------------------------------

      --  SINGLE_PROTECTED_DECLARATION ::=
      --    protected DEFINING_IDENTIFIER is PROTECTED_DEFINITION;

      --  Note: single protected declarations are not allowed in Ada 83 mode

      --  N_Single_Protected_Declaration
      --  Sloc points to PROTECTED
      --  Defining_Identifier (Node1)
      --  Protected_Definition (Node3)

      -------------------------------
      -- 9.4  Protected Definition --
      -------------------------------

      --  PROTECTED_DEFINITION ::=
      --      {PROTECTED_OPERATION_DECLARATION}
      --    [private
      --      {PROTECTED_ELEMENT_DECLARATION}]
      --    end [protected_IDENTIFIER]

      --  N_Protected_Definition
      --  Sloc points to first token of protected definition
      --  Visible_Declarations (List2)
      --  Private_Declarations (List4) (set to No_List if no private part)
      --  Has_Priority_Pragma (Flag6-Sem)

      ------------------------------------------
      -- 9.4  Protected Operation Declaration --
      ------------------------------------------

      --  PROTECTED_OPERATION_DECLARATION ::=
      --    SUBPROGRAM_DECLARATION
      --  | ENTRY_DECLARATION
      --  | REPRESENTATION_CLAUSE

      ----------------------------------------
      -- 9.4  Protected Element Declaration --
      ----------------------------------------

      --  PROTECTED_ELEMENT_DECLARATION ::=
      --    PROTECTED_OPERATION_DECLARATION | COMPONENT_DECLARATION

      -------------------------
      -- 9.4  Protected Body --
      -------------------------

      --  PROTECTED_BODY ::=
      --    protected body DEFINING_IDENTIFIER is
      --      {PROTECTED_OPERATION_ITEM}
      --    end [protected_IDENTIFIER];

      --  Note: protected bodies are not allowed in Ada 83 mode

      --  Gigi restriction: This node never appears.

      --  N_Protected_Body
      --  Sloc points to PROTECTED
      --  Defining_Identifier (Node1)
      --  Declarations (List3) protected operation items (and pragmas)
      --  Corresponding_Spec (Node5-Sem)

      -----------------------------------
      -- 9.4  Protected Operation Item --
      -----------------------------------

      --  PROTECTED_OPERATION_ITEM ::=
      --    SUBPROGRAM_DECLARATION
      --  | SUBPROGRAM_BODY
      --  | ENTRY_BODY
      --  | REPRESENTATION_CLAUSE

      ------------------------------
      -- 9.5.2  Entry Declaration --
      ------------------------------

      --  ENTRY_DECLARATION ::=
      --    entry DEFINING_IDENTIFIER
      --      [(DISCRETE_SUBTYPE_DEFINITION)] PARAMETER_PROFILE;

      --  N_Entry_Declaration
      --  Sloc points to ENTRY
      --  Defining_Identifier (Node1)
      --  Discrete_Subtype_Definition (Node4) (set to Empty if not present)
      --  Parameter_Specifications (List3) (set to No_List if no formal part)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      -----------------------------
      -- 9.5.2  Accept statement --
      -----------------------------

      --  ACCEPT_STATEMENT ::=
      --    accept entry_DIRECT_NAME
      --      [(ENTRY_INDEX)] PARAMETER_PROFILE [do
      --        HANDLED_SEQUENCE_OF_STATEMENTS
      --    end [entry_IDENTIFIER]];

      --  Gigi restriction: This node never appears.

      --  N_Accept_Statement
      --  Sloc points to ACCEPT
      --  Entry_Direct_Name (Node1)
      --  Entry_Index (Node5) (set to Empty if not present)
      --  Parameter_Specifications (List3) (set to No_List if no formal part)
      --  Handled_Statement_Sequence (Node4)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      ------------------------
      -- 9.5.2  Entry Index --
      ------------------------

      --  ENTRY_INDEX ::= EXPRESSION

      -----------------------
      -- 9.5.2  Entry Body --
      -----------------------

      --  ENTRY_BODY ::=
      --    entry DEFINING_IDENTIFIER ENTRY_BODY_FORMAL_PART ENTRY_BARRIER is
      --      DECLARATIVE_PART
      --    begin
      --      HANDLED_SEQUENCE_OF_STATEMENTS
      --    end [entry_IDENTIFIER];

      --  ENTRY_BARRIER ::= when CONDITION

      --  Note: we store the CONDITION of the ENTRY_BARRIER in the node for
      --  the ENTRY_BODY_FORMAL_PART to avoid the N_Entry_Body node getting
      --  too full (it would otherwise have too many fields)

      --  Gigi restriction: This node never appears.

      --  N_Entry_Body
      --  Sloc points to ENTRY
      --  Defining_Identifier (Node1)
      --  Entry_Body_Formal_Part (Node5)
      --  Declarations (List3)
      --  Handled_Statement_Sequence (Node4)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      -----------------------------------
      -- 9.5.2  Entry Body Formal Part --
      -----------------------------------

      --  ENTRY_BODY_FORMAL_PART ::=
      --    [(ENTRY_INDEX_SPECIFIATION)] PARAMETER_PROFILE

      --  Note that an entry body formal part node is present even if it is
      --  empty. This reflects the grammar, in which it is the components of
      --  the entry body formal part that are optional, not the entry body
      --  formal part itself. Also this means that the barrier condition
      --  always has somewhere to be stored.

      --  Gigi restriction: This node never appears.

      --  N_Entry_Body_Formal_Part
      --  Entry_Index_Specification (Node1) (set to Empty if not present)
      --  Parameter_Specifications (List3) (set to No_List if no formal part)
      --  Condition (Node5) from entry barrier of entry body

      --------------------------
      -- 9.5.2  Entry Barrier --
      --------------------------

      --  ENTRY_BARRIER ::= when CONDITION

      --------------------------------------
      -- 9.5.2  Entry Index Specification --
      --------------------------------------

      --  ENTRY_INDEX_SPECIFICATION ::=
      --    for DEFINING_IDENTIFIER in DISCRETE_SUBTYPE_DEFINITION

      --  Gigi restriction: This node never appears.

      --  N_Entry_Index_Specification
      --  Sloc points to FOR
      --  Defining_Identifier (Node1)
      --  Discrete_Subtype_Definition (Node4)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      ---------------------------------
      -- 9.5.3  Entry Call Statement --
      ---------------------------------

      --  ENTRY_CALL_STATEMENT ::= entry_NAME [ACTUAL_PARAMETER_PART];

      --  The parser may generate a procedure call for this construct. The
      --  semantic pass must correct this misidentification where needed.

      --  Gigi restriction: This node never appears.

      --  N_Entry_Call_Statement
      --  Sloc points to first token of name
      --  Name (Node2)
      --  Parameter_Associations (List3) (set to No_List if no
      --   actual parameter part)
      --  First_Named_Actual (Node4-Sem)

      ------------------------------
      -- 9.5.4  Requeue Statement --
      ------------------------------

      --  REQUEUE_STATEMENT ::= requeue entry_NAME [with abort];

      --  Note: requeue statements are not permitted in Ada 83 mode

      --  Gigi restriction: This node never appears.

      --  N_Requeue_Statement
      --  Sloc points to REQUEUE
      --  Name (Node2)
      --  Abort_Present (Flag1)

      --------------------------
      -- 9.6  Delay Statement --
      --------------------------

      --  DELAY_STATEMENT ::=
      --    DELAY_UNTIL_STATEMENT
      --  | DELAY_RELATIVE_STATEMENT

      --------------------------------
      -- 9.6  Delay Until Statement --
      --------------------------------

      --  DELAY_UNTIL_STATEMENT ::= delay until delay_EXPRESSION;

      --  Note: delay until statements are not permitted in Ada 83 mode

      --  Gigi restriction: This node never appears.

      --  N_Delay_Until_Statement
      --  Sloc points to DELAY
      --  Expression (Node3)

      -----------------------------------
      -- 9.6  Delay Relative Statement --
      -----------------------------------

      --  DELAY_RELATIVE_STATEMENT ::= delay delay_EXPRESSION;

      --  Gigi restriction: This node never appears.

      --  N_Delay_Relative_Statement
      --  Sloc points to DELAY
      --  Expression (Node3)

      ---------------------------
      -- 9.7  Select Statement --
      ---------------------------

      --  SELECT_STATEMENT ::=
      --    SELECTIVE_ACCEPT
      --  | TIMED_ENTRY_CALL
      --  | CONDITIONAL_ENTRY_CALL
      --  | ASYNCHRONOUS_SELECT

      -----------------------------
      -- 9.7.1  Selective Accept --
      -----------------------------

      --  SELECTIVE_ACCEPT ::=
      --    select
      --      [GUARD]
      --        SELECT_ALTERNATIVE
      --    {or
      --      [GUARD]
      --        SELECT_ALTERNATIVE}
      --    [else
      --      SEQUENCE_OF_STATEMENTS]
      --    end select;

      --  Gigi restriction: This node never appears.

      --  Note: the guard expression, if present, appears in the node for
      --  the select alternative.

      --  N_Selective_Accept
      --  Sloc points to SELECT
      --  Select_Alternatives (List1)
      --  Else_Statements (List4) (set to No_List if no else part)

      ------------------
      -- 9.7.1  Guard --
      ------------------

      --  GUARD ::= when CONDITION =>

      --  As noted above, the CONDITION that is part of a GUARD is included
      --  in the node for the select alernative for convenience.

      -------------------------------
      -- 9.7.1  Select Alternative --
      -------------------------------

      --  SELECT_ALTERNATIVE ::=
      --    ACCEPT_ALTERNATIVE
      --  | DELAY_ALTERNATIVE
      --  | TERMINATE_ALTERNATIVE

      -------------------------------
      -- 9.7.1  Accept Alternative --
      -------------------------------

      --  ACCEPT_ALTERNATIVE ::=
      --    ACCEPT_STATEMENT [SEQUENCE_OF_STATEMENTS]

      --  Gigi restriction: This node never appears.

      --  N_Accept_Alternative
      --  Sloc points to ACCEPT
      --  Accept_Statement (Node2)
      --  Condition (Node5) from the guard (set to Empty if no guard present)
      --  Statements (List3) (set to Empty_List if no statements)

      ------------------------------
      -- 9.7.1  Delay Alternative --
      ------------------------------

      --  DELAY_ALTERNATIVE ::=
      --    DELAY_STATEMENT [SEQUENCE_OF_STATEMENTS]

      --  Gigi restriction: This node never appears.

      --  N_Delay_Alternative
      --  Sloc points to DELAY
      --  Delay_Statement (Node2)
      --  Condition (Node5) from the guard (set to Empty if no guard present)
      --  Statements (List3) (set to Empty_List if no statements)

      ----------------------------------
      -- 9.7.1  Terminate Alternative --
      ----------------------------------

      --  TERMINATE_ALTERNATIVE ::= terminate;

      --  Gigi restriction: This node never appears.

      --  N_Terminate_Alternative
      --  Sloc points to TERMINATE
      --  Condition (Node5) from the guard (set to Empty if no guard present)

      -----------------------------
      -- 9.7.2  Timed Entry Call --
      -----------------------------

      --  TIMED_ENTRY_CALL ::=
      --    select
      --      ENTRY_CALL_ALTERNATIVE
      --    or
      --      DELAY_ALTERNATIVE
      --    end select;

      --  Gigi restriction: This node never appears.

      --  N_Timed_Entry_Call
      --  Sloc points to SELECT
      --  Entry_Call_Alternative (Node1)
      --  Delay_Alternative (Node4)

      -----------------------------------
      -- 9.7.2  Entry Call Alternative --
      -----------------------------------

      --  ENTRY_CALL_ALTERNATIVE ::=
      --    ENTRY_CALL_STATEMENT [SEQUENCE_OF_STATEMENTS]

      --  Gigi restriction: This node never appears.

      --  N_Entry_Call_Alternative
      --  Sloc points to first token of entry call statement
      --  Entry_Call_Statement (Node1)
      --  Statements (List3) (set to Empty_List if no statements)

      -----------------------------------
      -- 9.7.3  Conditional Entry Call --
      -----------------------------------

      --  CONDITIONAL_ENTRY_CALL ::=
      --    select
      --      ENTRY_CALL_ALTERNATIVE
      --    else
      --      SEQUENCE_OF_STATEMENTS
      --    end select;

      --  Gigi restriction: This node never appears.

      --  N_Conditional_Entry_Call
      --  Sloc points to SELECT
      --  Entry_Call_Alternative (Node1)
      --  Else_Statements (List4)

      --------------------------------
      -- 9.7.4  Asynchronous Select --
      --------------------------------

      --  ASYNCHRONOUS_SELECT ::=
      --    select
      --      TRIGGERING_ALTERNATIVE
      --    then abort
      --      ABORTABLE_PART
      --    end select;

      --  Note: asynchronous select is not permitted in Ada 83 mode

      --  Gigi restriction: This node never appears.

      --  N_Asynchronous_Select
      --  Sloc points to SELECT
      --  Triggering_Alternative (Node1)
      --  Abortable_Part (Node2)

      -----------------------------------
      -- 9.7.4  Triggering Alternative --
      -----------------------------------

      --  TRIGGERING_ALTERNATIVE ::=
      --    TRIGGERING_STATEMENT [SEQUENCE_OF_STATEMENTS]

      --  Gigi restriction: This node never appears.

      --  N_Triggering_Alternative
      --  Sloc points to first token of triggering statement
      --  Triggering_Statement (Node1)
      --  Statements (List3) (set to Empty_List if no statements)

      ---------------------------------
      -- 9.7.4  Triggering Statement --
      ---------------------------------

      --  TRIGGERING_STATEMENT ::= ENTRY_CALL_STATEMENT | DELAY_STATEMENT

      ---------------------------
      -- 9.7.4  Abortable Part --
      ---------------------------

      --  ABORTABLE_PART ::= SEQUENCE_OF_STATEMENTS

      --  Gigi restriction: This node never appears.

      --  N_Abortable_Part
      --  Sloc points to ABORT
      --  Statements (List3)

      --------------------------
      -- 9.8  Abort Statement --
      --------------------------

      --  ABORT_STATEMENT ::= abort task_NAME {, task_NAME};

      --  Gigi restriction: This node never appears.

      --  N_Abort_Statement
      --  Sloc points to ABORT
      --  Names (List2)

      -------------------------
      -- 10.1.1  Compilation --
      -------------------------

      --  COMPILATION ::= {COMPILATION_UNIT}

      --  There is no explicit node in the tree for a compilation, since in
      --  general the compiler is processing only a single compilation unit
      --  at a time. It is possible to parse multiple units in syntax check
      --  only mode, but they the trees are discarded in any case.

      ------------------------------
      -- 10.1.1  Compilation Unit --
      ------------------------------

      --  COMPILATION_UNIT ::=
      --    CONTEXT_CLAUSE LIBRARY_ITEM
      --  | CONTEXT_CLAUSE SUBUNIT

      --  N_Compilation_Unit
      --  Sloc points to first token of defining unit name
      --  Library_Unit (Node4-Sem) corresponding/parent spec/body
      --  Context_Items (List1) context items and pragmas preceding unit
      --  Private_Present (Flag1) set if library unit has private keyword
      --  Unit (Node2) library item or subunit
      --  Following_Pragmas (List3) pragmas after unit (set to No_List if
      --   no following pragmas)
      --  Has_No_Elab_Code (Flag17-Sem)
      --  Body_Required (Flag3-Sem) set for spec if body is required
      --  Acts_As_Spec (Flag4-Sem) flag for subprogram body with no spec
      --  Elaborate_Body_Present (Flag7-Sem) set if Elaborate_Body pragma
      --  First_Inlined_Subprogram (Node5-Sem)

      --------------------------
      -- 10.1.1  Library Item --
      --------------------------

      --  LIBRARY_ITEM ::=
      --    [private] LIBRARY_UNIT_DECLARATION
      --  | LIBRARY_UNIT_BODY
      --  | [private] LIBRARY_UNIT_RENAMING_DECLARATION

      --  Note: PRIVATE is not allowed in Ada 83 mode

      --  There is no explicit node in the tree for library item, instead
      --  the declaration or body, and the flag for private if present,
      --  appear in the N_Compilation_Unit clause.

      ----------------------------------------
      -- 10.1.1  Library Unit Declararation --
      ----------------------------------------

      --  LIBRARY_UNIT_DECLARATION ::=
      --    SUBPROGRAM_DECLARATION | PACKAGE_DECLARATION
      --  | GENERIC_DECLARATION    | GENERIC_INSTANTIATION

      -------------------------------------------------
      -- 10.1.1  Library Unit Renaming Declararation --
      -------------------------------------------------

      --  LIBRARY_UNIT_RENAMING_DECLARATION ::=
      --    PACKAGE_RENAMING_DECLARATION
      --  | GENERIC_RENAMING_DECLARATION
      --  | SUBPROGRAM_RENAMING_DECLARATION

      -------------------------------
      -- 10.1.1  Library unit body --
      -------------------------------

      --  LIBRARY_UNIT_BODY ::= SUBPROGRAM_BODY | PACKAGE_BODY

      ------------------------------
      -- 10.1.1  Parent Unit Name --
      ------------------------------

      --  PARENT_UNIT_NAME ::= NAME

      ----------------------------
      -- 10.1.2  Context clause --
      ----------------------------

      --  CONTEXT_CLAUSE ::= {CONTEXT_ITEM}

      --  Note: context items can also include pragma Elaborate and pragma
      --  Elaborate_Body, so these items can also appear in this list as
      --  well as other configuration pragmas that might appear. In addition,
      --  any pragmas appearing after the compilation unit, in particular,
      --  pragma Inline's are appended to the end of this list.

      --------------------------
      -- 10.1.2  Context_Item --
      --------------------------

      --  CONTEXT_ITEM ::= WITH_CLAUSE | USE_CLAUSE

      -------------------------
      -- 10.1.2  With clause --
      -------------------------

      --  WITH_CLAUSE ::=
      --    with library_unit_NAME {,library_unit_NAME};

      --  A separate With clause is built for each name, so that we have
      --  a Corresponding_Spec field for each with'ed spec. The flags
      --  First_Name and Last_Name are used to reconstruct the exact
      --  source form. When a list of names appears in one with clause,
      --  the first name in the list has First_Name set, and the last
      --  has Last_Name set. If the with clause has only one name, then
      --  both of the flags First_Name and Last_Name are set in this name.

      --  Note: in the case of implicit with's that are installed by the
      --  Rtsfind routine, Implicit_With is set, and the Sloc is typically
      --  set to Standard_Location, but it is incorrect to test the Sloc
      --  to find out if a with clause is implicit, test the flag instead.

      --  N_With_Clause
      --  Sloc points to first token of library unit name
      --  Name (Node2)
      --  Library_Unit (Node4-Sem)
      --  Corresponding_Spec (Node5-Sem)
      --  First_Name (Flag5) (set to True if first name or only one name)
      --  Last_Name (Flag6) (set to True if last name or only one name)
      --  Context_Installed (Flag3-Sem)
      --  Elaborate_Present (Flag4-Sem)
      --  Elaborate_All_Present (Flag1-Sem)
      --  Implicit_With (Flag17-Sem)

      ---------------------
      -- 10.2  Body stub --
      ---------------------

      --  BODY_STUB ::=
      --    SUBPROGRAM_BODY_STUB
      --  | PACKAGE_BODY_STUB
      --  | TASK_BODY_STUB
      --  | PROTECTED_BODY_STUB

      ----------------------------------
      -- 10.1.3  Subprogram Body Stub --
      ----------------------------------

      --  SUBPROGRAM_BODY_STUB ::=
      --    SUBPROGRAM_SPECIFICATION is separate;

      --  N_Subprogram_Body_Stub
      --  Sloc points to FUNCTION or PROCEDURE
      --  Specification (Node1)
      --  Library_Unit (Node4-Sem) points to the subunit
      --  Corresponding_Body (Node5-Sem)

      -------------------------------
      -- 10.1.3  Package Body Stub --
      -------------------------------

      --  PACKAGE_BODY_STUB ::=
      --    package body DEFINING_IDENTIFIER is separate;

      --  N_Package_Body_Stub
      --  Sloc points to PACKAGE
      --  Defining_Identifier (Node1)
      --  Library_Unit (Node4-Sem) points to the subunit
      --  Corresponding_Body (Node5-Sem)

      ----------------------------
      -- 10.1.3  Task Body Stub --
      ----------------------------

      --  TASK_BODY_STUB ::=
      --    task body DEFINING_IDENTIFIER is separate;

      --  N_Task_Body_Stub
      --  Sloc points to TASK
      --  Defining_Identifier (Node1)
      --  Library_Unit (Node4-Sem) points to the subunit
      --  Corresponding_Body (Node5-Sem)

      ---------------------------------
      -- 10.1.3  Protected Body Stub --
      ---------------------------------

      --  PROTECTED_BODY_STUB ::=
      --    protected body DEFINING_IDENTIFIER is separate;

      --  Note: protected body stubs are not allowed in Ada 83 mode

      --  N_Protected_Body_Stub
      --  Sloc points to PROTECTED
      --  Defining_Identifier (Node1)
      --  Library_Unit (Node4-Sem) points to the subunit
      --  Corresponding_Body (Node5-Sem)

      ---------------------
      -- 10.1.3  Subunit --
      ---------------------

      --  SUBUNIT ::= separate (PARENT_UNIT_NAME) PROPER_BODY

      --  N_Subunit
      --  Sloc points to SEPARATE
      --  Name (Node2) is the name of the parent unit
      --  Proper_Body (Node1) is the subunit body
      --  Corresponding_Stub (Node3-Sem) is the stub declaration for the unit.

      ---------------------------------
      -- 11.1  Exception Declaration --
      ---------------------------------

      --  EXCEPTION_DECLARATION ::= DEFINING_IDENTIFIER_LIST : exception;

      --  For consistency with object declarations etc, the parser converts
      --  the case of multiple identifiers being declared to a series of
      --  declarations in which the expression is copied, using the More_Ids
      --  and Prev_Ids flags to remember the souce form as described in the
      --  section on "Handling of Defining Identifier Lists".

      --  N_Exception_Declaration
      --  Sloc points to EXCEPTION
      --  Defining_Identifier (Node1)
      --  More_Ids (Flag5) (set to False if no more identifiers in list)
      --  Prev_Ids (Flag6) (set to False if no previous identifiers in list)

      ------------------------------------------
      -- 11.2  Handled Sequence Of Statements --
      ------------------------------------------

      --  HANDLED_SEQUENCE_OF_STATEMENTS ::=
      --      SEQUENCE_OF_STATEMENTS
      --    [exception
      --      EXCEPTION_HANDLER
      --      {EXCEPTION_HANDLER}]
      --    [at end
      --      cleanup_procedure_call (param, param, param, ...);]

      --  The AT END phrase is a GNAT extension to provide for cleanups. It is
      --  used only internally currently, but is considered to be syntactic.
      --  At the moment, the only cleanup action allowed is a single call to
      --  a parameterless procedure, and the Identifier field of the node is
      --  the procedure to be called. Also there is a current restriction
      --  that exception handles and a cleanup cannot be present in the same
      --  frame, so at least one of Exception_Handlers or the Identifier must
      --  be missing.

      --  The AT END cleanup handler protects only the sequence of statements
      --  (not the associated declarations of the parent), just like exception
      --  handlers. The big difference is that the cleanup procedure is called
      --  on either a normal or an abnormal exit from the statement sequence.

      --  Note: although in the Ada syntax, the sequence of statements can
      --  only contain statements, at the tree level, it is fine to mix in
      --  declarations into this statement sequence. This is used in some
      --  cases where a cleanup procedure is required to cover declarations
      --  as well as statements.

      --  N_Handled_Sequence_Of_Statements
      --  Sloc points to first token of first statement
      --  Statements (List3)
      --  Exception_Handlers (List4) (set to No_List if none present)
      --  Identifier (Node1) (set to Empty if no clean up procedure)
      --  Cleanup_Call (Node5-Sem) Cleanup call (set to Empty if no cleanup)
      --  First_Real_Statement (Node2-Sem)

      --  Note: the parent always contains a Declarations field which contains
      --  declarations associated with the handled sequence of statements. This
      --  is true even in the case of an accept statement (see description of
      --  the N_Accept_Statement node).

      --  Note the Identifier field is obsolescent, and will be removed
      --  once all instances of cleanup calls use Cleanup_Call ??? It is
      --  the name of a parameterless procedure call.

      -----------------------------
      -- 11.2  Exception Handler --
      -----------------------------

      --  EXCEPTION_HANDLER ::=
      --    when [CHOICE_PARAMETER_SPECIFICATION :]
      --      EXCEPTION_CHOICE {| EXCEPTION_CHOICE} =>
      --        SEQUENCE_OF_STATEMENTS

      --  Note: choice parameter specification is not allowed in Ada 83 mode

      --  N_Exception_Handler
      --  Sloc points to WHEN
      --  Choice_Parameter (Node2) (set to Empty if not present)
      --  Exception_Choices (List4)
      --  Statements (List3)

      ------------------------------------------
      -- 11.2  Choice parameter specification --
      ------------------------------------------

      --  CHOICE_PARAMETER_SPECIFICATION ::= DEFINING_IDENTIFIER

      ----------------------------
      -- 11.2  Exception Choice --
      ----------------------------

      --  EXCEPTION_CHOICE ::= exception_NAME | others

      --  Except in the case of OTHERS, no explicit node appears in the tree
      --  for exception choice. Instead the exception name appears directly.
      --  An OTHERS choice is represented by a N_Others_Choice node (see
      --  section 3.8.1.

      ---------------------------
      -- 11.3  Raise Statement --
      ---------------------------

      --  RAISE_STATEMENT ::= raise [exception_NAME];

      --  N_Raise_Statement
      --  Sloc points to RAISE
      --  Name (Node2) (set to Empty if no exception name present)
      --  No_Defer (Flag1-Sem)

      -------------------------------
      -- 12.1  Generic Declaration --
      -------------------------------

      --  GENERIC_DECLARATION ::=
      --    GENERIC_SUBPROGRAM_DECLARATION | GENERIC_PACKAGE_DECLARATION

      ------------------------------------------
      -- 12.1  Generic Subprogram Declaration --
      ------------------------------------------

      --  GENERIC_SUBPROGRAM_DECLARATION ::=
      --    GENERIC_FORMAL_PART SUBPROGRAM_SPECIFICATION;

      --  N_Generic_Subprogram_Declaration
      --  Sloc points to GENERIC
      --  Specification (Node1) subprogram specification
      --  Corresponding_Body (Node5-Sem)
      --  Generic_Formal_Declarations (List3) from generic formal part
      --  Parent_Spec (Node4-Sem)

      ---------------------------------------
      -- 12.1  Generic Package Declaration --
      ---------------------------------------

      --  GENERIC_PACKAGE_DECLARATION ::=
      --    GENERIC_FORMAL_PART PACKAGE_SPECIFICATION;

      --  Note: when we do generics right, the Activation_Chain_Entity entry
      --  for this node can be removed (since the expander won't see generic
      --  units any more).

      --  N_Generic_Package_Declaration
      --  Sloc points to GENERIC
      --  Specification (Node1) package specification
      --  Corresponding_Body (Node5-Sem)
      --  Generic_Formal_Declarations (List3) from generic formal part
      --  Parent_Spec (Node4-Sem)
      --  Activation_Chain_Entity (Node2-Sem)

      -------------------------------
      -- 12.1  Generic Formal Part --
      -------------------------------

      --  GENERIC_FORMAL_PART ::=
      --    generic {GENERIC_FORMAL_PARAMETER_DECLARATION | USE_CLAUSE}

      ------------------------------------------------
      -- 12.1  Generic Formal Parameter Declaration --
      ------------------------------------------------

      --  GENERIC_FORMAL_PARAMETER_DECLARATION ::=
      --    FORMAL_OBJECT_DECLARATION
      --  | FORMAL_TYPE_DECLARATION
      --  | FORMAL_SUBPROGRAM_DECLARATION
      --  | FORMAL_PACKAGE_DECLARATION

      ---------------------------------
      -- 12.3  Generic Instantiation --
      ---------------------------------

      --  GENERIC_INSTANTIATION ::=
      --    package DEFINING_PROGRAM_UNIT_NAME is
      --      new generic_package_NAME [GENERIC_ACTUAL_PART];
      --  | procedure DEFINING_PROGRAM_UNIT_NAME is
      --      new generic_procedure_NAME [GENERIC_ACTUAL_PART];
      --  | function DEFINING_DESIGNATOR is
      --      new generic_function_NAME [GENERIC_ACTUAL_PART];

      --  N_Package_Instantiation
      --  Sloc points to PACKAGE
      --  Defining_Unit_Name (Node1)
      --  Name (Node2)
      --  Parent_Spec (Node4-Sem)
      --  Generic_Associations (List3) (set to No_List if no
      --   generic actual part)

      --  N_Procedure_Instantiation
      --  Sloc points to PROCEDURE
      --  Defining_Unit_Name (Node1)
      --  Name (Node2)
      --  Parent_Spec (Node4-Sem)
      --  Generic_Associations (List3) (set to No_List if no
      --   generic actual part)

      --  N_Function_Instantiation
      --  Sloc points to FUNCTION
      --  Defining_Unit_Name (Node1)
      --  Name (Node2)
      --  Generic_Associations (List3) (set to No_List if no
      --   generic actual part)
      --  Parent_Spec (Node4-Sem)

      ------------------------------
      -- 12.3 Generic Actual Part --
      ------------------------------

      --  GENERIC_ACTUAL_PART ::=
      --    (GENERIC_ASSOCIATION {, GENERIC_ASSOCIATION})

      -------------------------------
      -- 12.3  Generic Association --
      -------------------------------

      --  GENERIC_ASSOCIATION ::=
      --    [generic_formal_parameter_SELECTOR_NAME =>]
      --      EXPLICIT_GENERIC_ACTUAL_PARAMETER

      --  Note: unlike the procedure call case, a generic association node
      --  is generated for every association, even if no formal is present.
      --  In this case the parser will leave the Selector_Name field set
      --  to Empty, to be filled in later by the semantic pass.

      --  N_Generic_Association
      --  Sloc points to first token of generic association
      --  Selector_Name (Node2) (set to Empty if no formal
      --   parameter selector name)
      --  Explicit_Generic_Actual_Parameter (Node1)

      ---------------------------------------------
      -- 12.3  Explicit Generic Actual Parameter --
      ---------------------------------------------

      --  EXPLICIT_GENERIC_ACTUAL_PARAMETER ::=
      --    EXPRESSION      | variable_NAME   | subprogram_NAME
      --  | entry_NAME      | SUBTYPE_MARK    | package_instance_NAME

      -------------------------------------
      -- 12.4  Formal Object Declaration --
      -------------------------------------

      --  FORMAL_OBJECT_DECLARATION ::=
      --    DEFINING_IDENTIFIER_LIST :
      --      MODE SUBTYPE_MARK [:= DEFAULT_EXPRESSION];

      --  Although the syntax allows multiple identifiers in the list, the
      --  semantics is as though successive declarations were given with
      --  identical type definition and expression components. To simplify
      --  semantic processing, the parser represents a multiple declaration
      --  case as a sequence of single declarations, using the More_Ids and
      --  Prev_Ids flags to preserve the original source form as described
      --  in the section on "Handling of Defining Identifier Lists".

      --  N_Formal_Object_Declaration
      --  Sloc points to first identifier
      --  Defining_Identifier (Node1)
      --  In_Present (Flag1)
      --  Out_Present (Flag17)
      --  Subtype_Mark (Node4)
      --  Expression (Node3) (set to Empty if no default expression)
      --  More_Ids (Flag5) (set to False if no more identifiers in list)
      --  Prev_Ids (Flag6) (set to False if no previous identifiers in list)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)

      -----------------------------------
      -- 12.5  Formal Type Declaration --
      -----------------------------------

      --  FORMAL_TYPE_DECLARATION ::=
      --    type DEFINING_IDENTIFIER [DISCRIMINANT_PART]
      --      is FORMAL_TYPE_DEFINITION;

      --  N_Formal_Type_Declaration
      --  Sloc points to TYPE
      --  Defining_Identifier (Node1)
      --  Formal_Type_Definition (Node3)
      --  Discriminant_Specifications (List4) (set to No_List if no
      --   discriminant part)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  Unknown_Discriminants_Present (Flag3) set if (<>) discriminant

      ----------------------------------
      -- 12.5  Formal type definition --
      ----------------------------------

      --  FORMAL_TYPE_DEFINITION ::=
      --    FORMAL_PRIVATE_TYPE_DEFINITION
      --  | FORMAL_DERIVED_TYPE_DEFINITION
      --  | FORMAL_DISCRETE_TYPE_DEFINITION
      --  | FORMAL_SIGNED_INTEGER_TYPE_DEFINITION
      --  | FORMAL_MODULAR_TYPE_DEFINITION
      --  | FORMAL_FLOATING_POINT_DEFINITION
      --  | FORMAL_ORDINARY_FIXED_POINT_DEFINITION
      --  | FORMAL_DECIMAL_FIXED_POINT_DEFINITION
      --  | FORMAL_ARRAY_TYPE_DEFINITION
      --  | FORMAL_ACCESS_TYPE_DEFINITION

      ---------------------------------------------
      -- 12.5.1  Formal Private Type Definition --
      ---------------------------------------------

      --  FORMAL_PRIVATE_TYPE_DEFINITION ::=
      --    [[abstract] tagged] [limited] private

      --  Note: TAGGED is not allowed in Ada 83 mode

      --  N_Formal_Private_Type_Definition
      --  Sloc points to PRIVATE
      --  Abstract_Present (Flag4)
      --  Tagged_Present (Flag1)
      --  Limited_Present (Flag17)

      --------------------------------------------
      -- 12.5.1  Formal Derived Type Definition --
      --------------------------------------------

      --  FORMAL_DERIVED_TYPE_DEFINITION ::=
      --    [abstract] new SUBTYPE_MARK [with private]

      --  Note: this construct is not allowed in Ada 83 mode

      --  N_Formal_Derived_Type_Definition
      --  Sloc points to NEW
      --  Subtype_Mark (Node4)
      --  Private_Present (Flag1)
      --  Abstract_Present (Flag4)

      ---------------------------------------------
      -- 12.5.2  Formal Discrete Type Definition --
      ---------------------------------------------

      --  FORMAL_DISCRETE_TYPE_DEFINITION ::= (<>)

      --  N_Formal_Discrete_Type_Definition
      --  Sloc points to <>

      ---------------------------------------------------
      -- 12.5.2  Formal Signed Integer Type Definition --
      ---------------------------------------------------

      --  FORMAL_SIGNED_INTEGER_TYPE_DEFINITION ::= range <>

      --  N_Formal_Signed_Integer_Type_Definition
      --  Sloc points to RANGE

      --------------------------------------------
      -- 12.5.2  Formal Modular Type Definition --
      --------------------------------------------

      --  FORMAL_MODULAR_TYPE_DEFINITION ::= mod <>

      --  N_Formal_Modular_Type_Definition
      --  Sloc points to MOD

      ----------------------------------------------
      -- 12.5.2  Formal Floating Point Definition --
      ----------------------------------------------

      --  FORMAL_FLOATING_POINT_DEFINITION ::= digits <>

      --  N_Formal_Floating_Point_Definition
      --  Sloc points to DIGITS

      ----------------------------------------------------
      -- 12.5.2  Formal Ordinary Fixed Point Definition --
      ----------------------------------------------------

      --  FORMAL_ORDINARY_FIXED_POINT_DEFINITION ::= delta <>

      --  N_Formal_Ordinary_Fixed_Point_Definition
      --  Sloc points to DELTA

      ---------------------------------------------------
      -- 12.5.2  Formal Decimal Fixed Point Definition --
      ---------------------------------------------------

      --  FORMAL_DECIMAL_FIXED_POINT_DEFINITION ::= delta <> digits <>

      --  Note: formal decimal fixed point definition not allowed in Ada 83

      --  N_Formal_Decimal_Fixed_Point_Definition
      --  Sloc points to DELTA

      ------------------------------------------
      -- 12.5.3  Formal Array Type Definition --
      ------------------------------------------

      --  FORMAL_ARRAY_TYPE_DEFINITION ::= ARRAY_TYPE_DEFINITION

      -------------------------------------------
      -- 12.5.4  Formal Access Type Definition --
      -------------------------------------------

      --  FORMAL_ACCESS_TYPE_DEFINITION ::= ACCESS_TYPE_DEFINITION

      -----------------------------------------
      -- 12.6  Formal Subprogram Declaration --
      -----------------------------------------

      --  FORMAL_SUBPROGRAM_DECLARATION ::=
      --    with SUBPROGRAM_SPECIFICATION [is SUBPROGRAM_DEFAULT];

      --  N_Formal_Subprogram_Declaration
      --  Sloc points to WITH
      --  Specification (Node1)
      --  Default_Name (Node2) (set to Empty if no subprogram default)
      --  Box_Present (Flag1)

      --  Note: if no subprogram default is present, then Name is set
      --  to Empty, and Box_Present is False.

      ------------------------------
      -- 12.6  Subprogram Default --
      ------------------------------

      --  SUBPROGRAM_DEFAULT ::= DEFAULT_NAME | <>

      --  There is no separate node in the tree for a subprogram default.
      --  Instead the parent (N_Formal_Subprogram_Declaration) node contains
      --  the default name or box indication, as needed.

      ------------------------
      -- 12.6  Default Name --
      ------------------------

      --  DEFAULT_NAME ::= NAME

      --------------------------------------
      -- 12.7  Formal Package Declaration --
      --------------------------------------

      --  FORMAL_PACKAGE_DECLARATION ::=
      --    with package DEFINING_IDENTIFIER
      --      is new generic_package_NAME FORMAL_PACKAGE_ACTUAL_PART;

      --  Note: formal package declarations not allowed in Ada 83 mode

      --  N_Formal_Package_Declaration
      --  Sloc points to WITH
      --  Defining_Identifier (Node1)
      --  Name (Node2)
      --  Generic_Associations (List3) (set to No_List if (<>) case or
      --   empty generic actual part)
      --  Box_Present (Flag1)

      --------------------------------------
      -- 12.7  Formal Package Actual Part --
      --------------------------------------

      --  FORMAL_PACKAGE_ACTUAL_PART ::=
      --    (<>) | [GENERIC_ACTUAL_PART]

      --  There is no explicit node in the tree for a formal package
      --  actual part. Instead the information appears in the parent node
      --  (i.e. the formal package declaration node itself).

      ---------------------------------
      -- 13.1  Representation clause --
      ---------------------------------

      --  REPRESENTATION_CLAUSE ::=
      --    ATTRIBUTE_DEFINITION_CLAUSE
      --  | ENUMERATION_REPRESENTATION_CLAUSE
      --  | RECORD_REPRESENTATION_CLAUSE
      --  | AT_CLAUSE

      ----------------------
      -- 13.1  Local Name --
      ----------------------

      --  LOCAL_NAME :=
      --    DIRECT_NAME
      --  | DIRECT_NAME'ATTRIBUTE_DESIGNATOR
      --  | library_unit_NAME

      --  The construct DIRECT_NAME'ATTRIBUTE_DESIGNATOR appears in the tree
      --  as an attribute reference, which has essentially the same form.

      ---------------------------------------
      -- 13.3  Attribute definition clause --
      ---------------------------------------

      --  ATTRIBUTE_DEFINITION_CLAUSE ::=
      --    for LOCAL_NAME'ATTRIBUTE_DESIGNATOR use EXPRESSION;
      --  | for LOCAL_NAME'ATTRIBUTE_DESIGNATOR use NAME;

      --  In Ada 83, the expression must be a simple expression and the
      --  local name must be a direct name.

      --  Note: The only attribute definition clause that is processed
      --  by Gigi is the alignment clause (for all other cases, the
      --  information is extracted by the front end and either results
      --  in setting entity information, e.g. Esize for the Size case,
      --  or in appropriate expansion actions (e.g. in the storage size
      --  case). For the alignment case, Gigi requires that the expression
      --  be an integer literal.

      --  N_Attribute_Definition_Clause
      --  Sloc points to FOR
      --  Name (Node2) the local name
      --  Chars (Name1) the identifier name from the attribute designator
      --  Expression (Node3) the expression or name

      ---------------------------------------------
      -- 13.4  Enumeration representation clause --
      ---------------------------------------------

      --  ENUMERATION_REPRESENTATION_CLAUSE ::=
      --    for first_subtype_LOCAL_NAME use ENUMERATION_AGGREGATE;

      --  In Ada 83, the name must be a direct name

      --  N_Enumeration_Representation_Clause
      --  Sloc points to FOR
      --  Identifier (Node1) direct name
      --  Array_Aggregate (Node4)

      ---------------------------------
      -- 13.4  Enumeration aggregate --
      ---------------------------------

      --  ENUMERATION_AGGREGATE ::= ARRAY_AGGREGATE

      ------------------------------------------
      -- 13.5.1  Record representation clause --
      ------------------------------------------

      --  RECORD_REPRESENTATION_CLAUSE ::=
      --    for first_subtype_LOCAL_NAME use
      --      record [MOD_CLAUSE]
      --        {COMPONENT_CLAUSE}
      --      end record;

      --  Gigi restriction: Mod_Clause is always Empty (if present it is
      --  replaced by a corresponding Alignment attribute definition clause).

      --  N_Record_Representation_Clause
      --  Sloc points to FOR
      --  Identifier (Node1) direct name
      --  Mod_Clause (Node2) (set to Empty if no mod clause present)
      --  Component_Clauses (List3)

      ------------------------------
      -- 13.5.1  Component clause --
      ------------------------------

      --  COMPONENT_CLAUSE ::=
      --    component_LOCAL_NAME at POSITION
      --      range FIRST_BIT .. LAST_BIT;

      --  N_Component_Clause
      --  Sloc points to AT
      --  Component_Name (Node1) points to Name or Attribute_Reference
      --  Position (Node2)
      --  First_Bit (Node3)
      --  Last_Bit (Node4)

      ----------------------
      -- 13.5.1  Position --
      ----------------------

      --  POSITION ::= static_EXPRESSION

      -----------------------
      -- 13.5.1  First_Bit --
      -----------------------

      --  FIRST_BIT ::= static_SIMPLE_EXPRESSION

      ----------------------
      -- 13.5.1  Last_Bit --
      ----------------------

      --  LAST_BIT ::= static_SIMPLE_EXPRESSION

      --------------------------
      -- 13.8  Code statement --
      --------------------------

      --  CODE_STATEMENT ::= QUALIFIED_EXPRESSION;

      --  N_Code_Statement
      --  Sloc points to first token of subtype mark
      --  Expression (Node3)

      ------------------------
      -- 13.12  Restriction --
      ------------------------

      --  RESTRICTION ::=
      --    restriction_IDENTIFIER
      --  | restriction_parameter_IDENTIFIER => EXPRESSION

      --  There is no explicit node for restrictions. Instead the restriction
      --  appears in normal pragma syntax as a pragma argument association,
      --  which has the same syntactic form.

      --------------------------
      -- B.2  Shift Operators --
      --------------------------

      --  Calls to the intrinsic shift functions are converted to one of
      --  the following shift nodes, which have the form of normal binary
      --  operator names. Note that for a given shift operation, one node
      --  covers all possible types, as for normal operators.

      --  Note: it is perfectly permissible for the expander to generate
      --  shift operation nodes directly, in which case they will be analyzed
      --  and parsed in the usual manner.

      --  Sprint syntax: shift-function-name!(expr, count)

      --  Note: the Left_Opnd field holds the first argument (the value to
      --  be shifted). The Right_Opnd field holds the second argument (the
      --  shift count). The Chars field is the name of the intrinsic function.

      --  N_Op_Rotate_Left
      --  Sloc points to the function name
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Rotate_Right
      --  Sloc points to the function name
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Shift_Left
      --  Sloc points to the function name
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Shift_Right_Arithmetic
      --  Sloc points to the function name
      --  plus fields for binary operator
      --  plus fields for expression

      --  N_Op_Shift_Right
      --  Sloc points to the function name
      --  plus fields for binary operator
      --  plus fields for expression

   --------------------------
   -- Obsolescent Features --
   --------------------------

      --  The syntax descriptions and tree nodes for obsolescent features are
      --  grouped together, corresponding to their location in appendix I in
      --  the RM. However, parsing and semantic analysis for these constructs
      --  is located in an appropriate chapter (see individual notes).

      ---------------------------
      -- I.3  Delta Constraint --
      ---------------------------

      --  Note: the parse routine for this construct is located in section
      --  3.5.9 of Par-Ch3, and semantic analysis is in Sem_Ch3, which is
      --  where delta constraint logically belongs.

      --  DELTA CONSTRAINT ::= DELTA STATIC_EXPRESSION [RANGE_CONSTRAINT]

      --  N_Delta_Constraint
      --  Sloc points to DELTA
      --  Delta_Expression (Node3)
      --  Range_Constraint (Node4) (set to Empty if not present)

      --------------------
      -- I.7  At Clause --
      --------------------

      --  AT_CLAUSE ::= for DIRECT_NAME use at EXPRESSION;

      --  Note: the parse routine for this construct is located in Par-Ch13,
      --  and the semantic analysis is in Sem_Ch13, where at clause logically
      --  belongs if it were not obsolescent.

      --  Note: in Ada 83 the expression must be a simple expression

      --  Gigi restriction: This node never appears, it is rewritten as an
      --  address attribute definition clause.

      --  N_At_Clause
      --  Sloc points to FOR
      --  Identifier (Node1)
      --  Expression (Node3)

      ---------------------
      -- I.8  Mod clause --
      ---------------------

      --  MOD_CLAUSE ::= at mod static_EXPRESSION;

      --  Note: the parse routine for this construct is located in Par-Ch13,
      --  and the semantic analysis is in Sem_Ch13, where mod clause logically
      --  belongs if it were not obsolescent.

      --  Note: in Ada 83, the expression must be a simple expression

      --  Gigi restriction: this node never appears. It is replaced
      --  by a corresponding Alignment attribute definition clause.

      --  N_Mod_Clause
      --  Sloc points to AT
      --  Expression (Node3)

   --------------------
   -- Semantic Nodes --
   --------------------

   --  These semantic nodes are used to hold additional semantic information.
   --  They are inserted into the tree as a resut of semantic processing.
   --  Although there are no legitimate source syntax constructions that
   --  correspond directly to these nodes, we need a source syntax for the
   --  reconstructed tree printed by Sprint, and the node descriptions here
   --  show this syntax.

      ---------------------
      -- Concat Multiple --
      ---------------------

      --  During semantic analysis, this node is created if a sequence of
      --  concatenation nodes construct a single concatenation result. The
      --  creation of this node is used to optimize both compile time
      --  evaluation and run time processing for concatenation, by avoiding
      --  the construction of intermediate results.

      --  Sprint syntax: expression && expression && expression ..

      --  N_Concat_Multiple
      --  Sloc points to first of the & operators
      --  Expressions (List1) points to list of operands
      --  plus fields for expression

      ----------------------------
      -- Conditional Expression --
      ----------------------------

      --  This node is used to represent an expression corresponding to the
      --  C construct (condition ? then-expression : else_expression), where
      --  Expressions is a three element list, whose first expression is the
      --  condition, and whose second and third expressions are the then and
      --  else expressions respectively.

      --  Sprint syntax: (if expr then expr else expr)

      --  N_Conditional_Expression
      --  Expressions (List1)
      --  Then_Actions (List2-Sem)
      --  Else_Actions (List3-Sem)
      --  plus fields for expression

      -------------------
      -- Expanded_Name --
      -------------------

      --  The N_Expanded_Name node is used to represent a selected component
      --  name that has been resolved to an expanded name. The semantic phase
      --  replaces N_Selected_Component nodes that represent names by the use
      --  of this node, leaving the N_Selected_Component node used only when
      --  the prefix is a record or protected type.

      --  The fields of the N_Expanded_Name node are layed out identically
      --  to those of the N_Selected_Component node, allowing conversion of
      --  an expanded name node to a selected component node to be done
      --  easily, see Sinfo.CN.Change_Selected_Component_To_Expanded_Name.

      --  There is no special sprint syntax for an expanded name.

      --  N_Expanded_Name
      --  Sloc points to the period
      --  Chars (Name1) copy of Chars field of selector name
      --  Prefix (Node3)
      --  Selector_Name (Node2)
      --  Entity (Node4-Sem)
      --  Redundant_Use (Flag3-Sem) set for redundant use clause
      --  Has_Private_View (Flag11-Sem) set in generic units.
      --  Is_Current_Instance (Flag14-Sem) set if entity is enclosing type.
      --  plus fields for expression

      ------------------------
      -- Expression Actions --
      ------------------------

      --  The N_Expression_Actions node is inserted into an expression as a
      --  result of semantic processing that indicates that some actions
      --  (e.g. the creation of some implicit types) are required as part
      --  of the processing for an expression. The list of actions can
      --  include declarations, statements and expressions.

      --  Sprint syntax: [action; action; action; expression]

      --  N_Expression_Actions
      --  Sloc is set to some relevant token in the original source
      --  Actions (List1)
      --  Expression (Node3)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  plus fields for expression

      --------------------
      -- Free Statement --
      --------------------

      --  The N_Free_Statement node is generated as a result of a call to an
      --  instantiation of Unchecked_Deallocation. The instantiation of this
      --  generic is handled specially and generates this node directly.

      --  Sprint syntax: free expression

      --  N_Free_Statement
      --  Sloc is copied from call to unchecked deallocation procedure
      --  Expression (Node3) argument to unchecked deallocation call
      --  Storage_Pool (Node1-Sem)
      --  Procedure_To_Call (Node4-Sem)

      -------------------
      -- Freeze Entity --
      -------------------

      --  This node marks the point in a declarative part at which an entity
      --  declared therein becomes frozen. The expander places initialization
      --  procedures for types at those points. Gigi uses the freezing point
      --  to elaborate entities that may depend on previous private types.

      --  The Entity field points back to the entity for the type (whose
      --  Freeze_Node field points back to this freeze node). Itypes can
      --  be present in the case where freezing generates associated types,
      --  or in the case of an Itype which itself needs freezing (in this
      --  case the Itype sits on its own freeze node)

      --  The Actions field contains a list of declarations and statements
      --  generated by the expander which are associated with the freeze
      --  node, and are elaborated as though the freeze node were replaced
      --  by this sequence of actions.

      --  Note: the Sloc field in the freeze node references a construct
      --  associated with the freezing point. This is used for posting
      --  messages in some error/warning situations, e.g. the case where
      --  a primitive operation of a tagged type is declared too late.

      --  Sprint syntax: freeze entity-name [
      --                   freeze actions
      --                 ]

      --  N_Freeze_Entity
      --  Sloc set near freeze point (see above special note)
      --  Entity (Node4-Sem)
      --  TSS_Elist (Elist3-Sem) (set to No_Elist if no associated TSS's)
      --  Actions (List1) (set to No_List if no freeze actions)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  First_Subtype_Link (Node5-Sem) (set to Empty if no link)
      --  Has_Dynamic_Itype (Flag14-Sem)

      --------------------------------
      -- Implicit Label Declaration --
      --------------------------------

      --  An implicit label declaration is created for every occurrence of a
      --  label on a statement or a label on a block or loop. It is chained
      --  in the declarations of the innermost enclosing block as specified
      --  in RM section 5.1 (3).

      --  Note: from the grammar, this might better be called an implicit
      --  statement identifier declaration, but the term we choose seems
      --  friendlier, since at least informally statement identifiers are
      --  called labels in both cases (i.e. when used in labels, and when
      --  used as the identifiers of blocks and loops).

      --  Note: although this is logically a semantic node, since it does
      --  not correspond directly to a source syntax construction, these
      --  nodes are actually created by the parser in a post pass done just
      --  after parsing is complete, before semantic analysis is started (see
      --  the Par.Labl subunit in file par-labl.adb).

      --  Sprint syntax: labelname : label;

      --  The label field in the implicit label node points to the node
      --  containing the label (N_Label, N_Loop_Statement, N_Block_Statement).

      --  N_Implicit_Label_Declaration
      --  Sloc points to the << of the label
      --  Defining_Identifier (Node1)
      --  Label (Node2) points to the associated node

      --------------------
      -- Implicit Types --
      --------------------

      --  Normally implicit types are attached to the node to which they
      --  apply. For example, in the case of a subexpression which requires
      --  implicit types, the implicit types are attached to the subexpression
      --  node. However, in certain situations, there is no node to which the
      --  list of implicit types can be attached, and in this situation, an
      --  N_Implicit_Types node is created to hold the list.

      --  Sprint syntax: implicit type type-name is <Einfo.Entity_Kind name>.

      --  N_Implicit_Types
      --  Sloc is copied from the node giving rise to first implicit type
      --  First_Itype (Node2-Sem)
      --  Has_Dynamic_Itype (Flag14-Sem)

      --------------------
      -- Interpretation --
      --------------------

      --  During overload resolution, the Etype field of a possibly overloaded
      --  reference is used to point to a chain of N_Interpretation nodes, one
      --  for each possible interpretation. See Sem_Type for further details.

      --  Note that these nodes are simply for temporary use by the semantic
      --  analyzer. Logically they are not part of the tree, and are always
      --  eventually eliminated when final type determination is complete.
      --  Gigi will never see these nodes in the final tree.

      --  Sprint syntax: none, since Sprint does not print type information

      --  N_Interpretation
      --  Sloc is copied from the node to which the interpretation applies
      --  Chars (Name1) is copied from Chars (Etype)
      --  Next_Interp (Node2-Sem)
      --  Entity (Node4-Sem)
      --  Etype (Node5-Sem)

      ----------------------------
      -- Raise_Constraint_Error --
      ----------------------------

      --  This node is created during semantic analysis to replace a node
      --  for an expression that is determined to definitely raise constraint
      --  error. The creation of this node will usually be accompanied by a
      --  warning message (unless it appears within the right operand of a
      --  short circuit form whose left argument is static and decisively
      --  eliminates elaboration of the constraint error.

      --  Sprint syntax: [constraint_error]

      --  N_Raise_Constraint_Error
      --  Sloc is copied from the expression generating the exception
      --  plus fields for expression

      ---------------
      -- Reference --
      ---------------

      --  For a number of purposes, we need to construct references to objects.
      --  These references are subsequently treated as normal access values.
      --  An example is the construction of the parameter block passed to a
      --  task entry. The N_Reference node is provided for this purpose. It is
      --  similar in effect to the use of the Unrestricted_Access attribute,
      --  and like Unrestricted_Access can be applied to objects which would
      --  not be valid prefixes for the Unchecked_Access attribute (e.g.
      --  objects which are not aliased, and slices). In addition it can be
      --  applied to composite type values as well as objects, including string
      --  values and aggregates.

      --  Note: we use the Prefix field for this expression so that the
      --  resulting node can be treated using common code with the attribute
      --  nodes for the 'Access and related attributes. Logically it would make
      --  more sense to call it an Expression field, but then we would have to
      --  special case the treatment of the N_Reference node.

      --  Sprint syntax: prefix'reference

      --  N_Reference
      --  Sloc is copied from the expression
      --  Prefix (Node3)
      --  First_Itype (Node2-Sem) (set to Empty if no Itypes)
      --  Has_Dynamic_Itype (Flag14-Sem)
      --  plus fields for expression

      -------------------------------
      -- Unchecked Type Conversion --
      -------------------------------

      --  An unchecked type conversion node represents the semantic action
      --  corresponding to a call to an instantiation of Unchecked_Conversion.
      --  It is generated as a result of actual use of Unchecked_Conversion
      --  and also the expander generates unchecked type conversion nodes
      --  directly for expansion of complex semantic actions.

      --  Note: an unchecked type conversion is a variable as far as the
      --  semantics are concerned, which is convenient for the expander.
      --  This does not change what Ada source programs are legal, since
      --  clearly a function call to an instantiation of Unchecked_Conversion
      --  is not a variable in any case.

      --  Sprint syntax: subtype-mark!(expression).

      --  N_Unchecked_Type_Conversion
      --  Sloc points to related node in source
      --  Subtype_Mark (Node4)
      --  Expression (Node3)
      --  plus fields for expression

   -----------
   -- Empty --
   -----------

   --  N_Empty
   --  Chars (Name1) is set to No_Name
   --  Used as the contents of the Nkind field of the dummy Empty node
   --  and in some other situations to indicate an uninitialized value.

   -----------
   -- Error --
   -----------

   --  N_Error
   --  Chars (Name1) is set to Error_Name
   --  Used as the contents of the Nkind field of the dummy Error node

   --------------------------
   -- Node Type Definition --
   --------------------------

   --  The following is the definition of the Node_Kind type. As previously
   --  discussed, this is separated off to allow rearrangement of the order
   --  to facilitiate definition of subtype ranges. The comments show the
   --  subtype classes which apply to each set of node kinds. The first
   --  entry in the comment characterizes the following list of nodes.

   type Node_Kind is (
      N_Unused_At_Start,

      --  N_Representation_Clause
      N_At_Clause,
      N_Component_Clause,
      N_Enumeration_Representation_Clause,
      N_Mod_Clause,
      N_Record_Representation_Clause,

      --  N_Representation_Clause, N_Has_Chars

      N_Attribute_Definition_Clause,

      --  N_Has_Chars
      N_Empty,
      N_Error,
      N_Pragma,
      N_Pragma_Argument_Association,

      --  N_Entity, N_Has_Etype, N_Has_Chars
      N_Defining_Character_Literal,
      N_Defining_Identifier,
      N_Defining_Operator_Symbol,

      --  N_Has_Etype, N_Has_Chars

      N_Interpretation,

      --  N_Subexpr, N_Has_Etype, N_Has_Chars, N_Subexpr_Has_Entity
      N_Expanded_Name,

      --  N_Direct_Name, N_Subexpr, N_Has_Etype,
      --  N_Has_Chars, N_Subexpr_Has_Entity
      N_Identifier,
      N_Character_Literal,
      N_Operator_Symbol,

      --  N_Binary_Op, N_Op, N_Subexpr, N_Has_Etype,
      --  N_Has_Chars, N_Subexpr_Has_Entity
      N_Op_Add,
      N_Op_And,
      N_Op_Concat,
      N_Op_Divide,
      N_Op_Eq,
      N_Op_Expon,
      N_Op_Ge,
      N_Op_Gt,
      N_Op_Le,
      N_Op_Lt,
      N_Op_Mod,
      N_Op_Multiply,
      N_Op_Ne,
      N_Op_Or,
      N_Op_Rem,
      N_Op_Subtract,
      N_Op_Xor,

      --  N_Binary_Op, N_Op, N_Subexpr, N_Has_Etype,
      --  N_Op_Shift, N_Has_Chars, N_Subexpr_Has_Entity
      N_Op_Rotate_Left,
      N_Op_Rotate_Right,
      N_Op_Shift_Left,
      N_Op_Shift_Right,
      N_Op_Shift_Right_Arithmetic,

      --  N_Unary_Op, N_Op, N_Subexpr, N_Has_Etype,
      --  N_Has_Chars, N_Subexpr_Has_Entity
      N_Op_Abs,
      N_Op_Minus,
      N_Op_Not,
      N_Op_Plus,

      --  N_Subexpr, N_Has_Etype, N_Subexpr_Has_Entity
      N_Attribute_Reference,

      --  N_Subexpr, N_Has_Etype
      N_And_Then,
      N_Concat_Multiple,
      N_Conditional_Expression,
      N_Explicit_Dereference,
      N_Function_Call,
      N_In,
      N_Indexed_Component,
      N_Integer_Literal,
      N_Not_In,
      N_Null,
      N_Or_Else,
      N_Procedure_Call_Statement,
      N_Qualified_Expression,
      N_Raise_Constraint_Error,
      N_Range,
      N_Real_Literal,
      N_Selected_Component,
      N_Type_Conversion,
      N_Unchecked_Type_Conversion,

      --  N_Subexpr, N_Has_Etype, N_Has_Itypes
      N_Allocator,
      N_Aggregate,
      N_Expression_Actions,
      N_Extension_Aggregate,
      N_Reference,
      N_Slice,
      N_String_Literal,

      --  N_Has_Etype, N_Has_Itypes
      N_Subtype_Indication,

      --  N_Has_Itypes
      N_Component_Declaration,
      N_Entry_Body,
      N_Entry_Declaration,
      N_Entry_Index_Specification,
      N_Formal_Object_Declaration,
      N_Formal_Type_Declaration,
      N_Freeze_Entity,
      N_Full_Type_Declaration,
      N_Incomplete_Type_Declaration,
      N_Implicit_Types,
      N_Loop_Parameter_Specification,
      N_Object_Declaration,
      N_Private_Extension_Declaration,
      N_Private_Type_Declaration,
      N_Subtype_Declaration,
      N_Protected_Type_Declaration,
      N_Accept_Statement,

      --  N_Has_Itypes, N_Subprogram_Specification
      N_Function_Specification,
      N_Procedure_Specification,

      --  N_Has_Itypes, N_Access_To_Subprogram_Definition
      N_Access_Function_Definition,
      N_Access_Procedure_Definition,

      --  N_Has_Itypes, N_Later_Decl_Item,
      N_Task_Type_Declaration,

      --  N_Body_Stub, N_Later_Decl_Item
      N_Package_Body_Stub,
      N_Protected_Body_Stub,
      N_Subprogram_Body_Stub,
      N_Task_Body_Stub,

      --  N_Generic_Instantiation, N_Later_Decl_Item
      N_Function_Instantiation,
      N_Package_Instantiation,
      N_Procedure_Instantiation,

      --  N_Unit_Body, N_Later_Decl_Item
      N_Package_Body,
      N_Subprogram_Body,

      --  N_Later_Decl_Item
      N_Implicit_Label_Declaration,
      N_Package_Declaration,
      N_Single_Task_Declaration,
      N_Subprogram_Declaration,
      N_Task_Body,
      N_Use_Package_Clause,

      --  N_Generic_Declaration, N_Later_Decl_Item
      N_Generic_Package_Declaration,
      N_Generic_Subprogram_Declaration,

      --  N_Array_Type_Definition
      N_Constrained_Array_Definition,
      N_Unconstrained_Array_Definition,

      --  N_Renaming_Declaration
      N_Exception_Renaming_Declaration,
      N_Object_Renaming_Declaration,
      N_Package_Renaming_Declaration,
      N_Subprogram_Renaming_Declaration,

      --  N_Generic_Renaming_Declarations, N_Renaming_Declaration
      N_Generic_Function_Renaming_Declaration,
      N_Generic_Package_Renaming_Declaration,
      N_Generic_Procedure_Renaming_Declaration,

      --  N_Statement
      N_Abort_Statement,
      N_Assignment_Statement,
      N_Asynchronous_Select,
      N_Block_Statement,
      N_Case_Statement,
      N_Code_Statement,
      N_Conditional_Entry_Call,
      N_Delay_Relative_Statement,
      N_Delay_Until_Statement,
      N_Entry_Call_Statement,
      N_Exit_Statement,
      N_Free_Statement,
      N_Goto_Statement,
      N_If_Statement,
      N_Loop_Statement,
      N_Null_Statement,
      N_Raise_Statement,
      N_Requeue_Statement,
      N_Return_Statement,
      N_Selective_Accept,
      N_Timed_Entry_Call,

      --  Other nodes (not part of any subtype class)
      N_Abortable_Part,
      N_Abstract_Subprogram_Declaration,
      N_Accept_Alternative,
      N_Access_Definition,
      N_Access_To_Object_Definition,
      N_Case_Statement_Alternative,
      N_Compilation_Unit,
      N_Component_Association,
      N_Component_List,
      N_Derived_Type_Definition,
      N_Decimal_Fixed_Point_Definition,
      N_Defining_Program_Unit_Name,
      N_Delay_Alternative,
      N_Delta_Constraint,
      N_Designator,
      N_Digits_Constraint,
      N_Discriminant_Association,
      N_Discriminant_Specification,
      N_Elsif_Part,
      N_Enumeration_Type_Definition,
      N_Entry_Body_Formal_Part,
      N_Entry_Call_Alternative,
      N_Exception_Declaration,
      N_Exception_Handler,
      N_Floating_Point_Definition,
      N_Formal_Decimal_Fixed_Point_Definition,
      N_Formal_Derived_Type_Definition,
      N_Formal_Discrete_Type_Definition,
      N_Formal_Floating_Point_Definition,
      N_Formal_Modular_Type_Definition,
      N_Formal_Ordinary_Fixed_Point_Definition,
      N_Formal_Package_Declaration,
      N_Formal_Private_Type_Definition,
      N_Formal_Signed_Integer_Type_Definition,
      N_Formal_Subprogram_Declaration,
      N_Generic_Association,
      N_Handled_Sequence_Of_Statements,
      N_Index_Or_Discriminant_Constraint,
      N_Iteration_Scheme,
      N_Label,
      N_Modular_Type_Definition,
      N_Number_Declaration,
      N_Ordinary_Fixed_Point_Definition,
      N_Others_Choice,
      N_Package_Specification,
      N_Parameter_Association,
      N_Parameter_Specification,
      N_Protected_Body,
      N_Protected_Definition,
      N_Range_Constraint,
      N_Real_Range_Specification,
      N_Record_Definition,
      N_Signed_Integer_Type_Definition,
      N_Single_Protected_Declaration,
      N_Subunit,
      N_Task_Definition,
      N_Terminate_Alternative,
      N_Triggering_Alternative,
      N_Use_Type_Clause,
      N_Variant,
      N_Variant_Part,
      N_With_Clause,
      N_Unused_At_End);

   ----------------------------
   -- Node Class Definitions --
   ----------------------------

   subtype N_Access_To_Subprogram_Definition is Node_Kind range
     N_Access_Function_Definition ..
     N_Access_Procedure_Definition;

   subtype N_Array_Type_Definition is Node_Kind range
     N_Constrained_Array_Definition ..
     N_Unconstrained_Array_Definition;

   subtype N_Binary_Op is Node_Kind range
     N_Op_Add ..
     N_Op_Shift_Right_Arithmetic;

   subtype N_Body_Stub is Node_Kind range
     N_Package_Body_Stub ..
     N_Task_Body_Stub;

   subtype N_Direct_Name is Node_Kind range
     N_Identifier ..
     N_Operator_Symbol;

   subtype N_Entity is Node_Kind range
     N_Defining_Character_Literal ..
     N_Defining_Operator_Symbol;

   subtype N_Generic_Declaration is Node_Kind range
     N_Generic_Package_Declaration ..
     N_Generic_Subprogram_Declaration;

   subtype N_Generic_Instantiation is Node_Kind range
     N_Function_Instantiation ..
     N_Procedure_Instantiation;

   subtype N_Generic_Renaming_Declaration is Node_Kind range
     N_Generic_Function_Renaming_Declaration ..
     N_Generic_Procedure_Renaming_Declaration;

   subtype N_Has_Chars is Node_Kind range
     N_Attribute_Definition_Clause ..
     N_Op_Plus;

   subtype N_Has_Etype is Node_Kind range
     N_Defining_Character_Literal ..
     N_Subtype_Indication;

   subtype N_Has_Itypes is Node_Kind range
     N_Allocator ..
     N_Task_Type_Declaration;
   --  Nodes having First_Itype and Has_Dynamic_Itype fields

   subtype N_Op_Shift is Node_Kind range
     N_Op_Rotate_Left ..
     N_Op_Shift_Right_Arithmetic;

   subtype N_Later_Decl_Item is Node_Kind range
     N_Package_Body_Stub .. N_Generic_Subprogram_Declaration;
   --  Note: this is Ada 83 relevant only (see Ada 83 RM 3.9 (2)) and
   --  includes only those items which can appear as later declarative
   --  items. This also includes N_Implicit_Label_Declaration which is
   --  not specifically in the grammar but may appear as a valid later
   --  declarative items. It does NOT include N_Pragma which can also
   --  appear among later declarative items.

   subtype N_Op is Node_Kind range
     N_Op_Add ..
     N_Op_Plus;

   subtype N_Renaming_Declaration is Node_Kind range
     N_Exception_Renaming_Declaration ..
     N_Generic_Procedure_Renaming_Declaration;

   subtype N_Representation_Clause is Node_Kind range
     N_At_Clause ..
     N_Attribute_Definition_Clause;

   subtype N_Statement is Node_Kind range
     N_Abort_Statement ..
     N_Timed_Entry_Call;
   --  Note that this includes all statement types except for the cases of the
   --  N_Procedure_Call_Statement which is considered to be a subexpression
   --  (since overloading is possible, so it needs to go through the normal
   --  overloading resolution for expressions), and also the special case of
   --  N_Accept_Statement (which has Itypes and therefore cannot be fit into
   --  the range of statement types).

   subtype N_Subexpr is Node_Kind range
     N_Expanded_Name ..
     N_String_Literal;
   --  Nodes with expression fields

   subtype N_Subexpr_Has_Entity is Node_Kind range
     N_Expanded_Name ..
     N_Attribute_Reference;
   --  Subexpression nodes that have Entity fields

   subtype N_Subprogram_Specification is Node_Kind range
     N_Function_Specification ..
     N_Procedure_Specification;

   subtype N_Unary_Op is Node_Kind range
     N_Op_Abs ..
     N_Op_Plus;

   subtype N_Unit_Body is Node_Kind range
     N_Package_Body ..
     N_Subprogram_Body;

   ---------------------------
   -- Node Access Functions --
   ---------------------------

   --  The following functions return the contents of the indicated field of
   --  the node referenced by the argument, which is a Node_Id. They provide
   --  logical access to fields in the node which could be accessed using the
   --  Atree.Unchecked_Access package, but the idea is always to use these
   --  higher level routines which preserve strong typing. In debug mode,
   --  these routines check that they are being applied to an appropriate
   --  node, as well as checking that the node is in range.

   function Abort_Present
     (N : Node_Id) return Boolean;    -- Flag1

   function Abortable_Part
     (N : Node_Id) return Node_Id;    -- Node2

   function Abstract_Present
     (N : Node_Id) return Boolean;    -- Flag4

   function Accept_Statement
     (N : Node_Id) return Node_Id;    -- Node2

   function Actions
     (N : Node_Id) return List_Id;    -- List1

   function Activation_Chain_Entity
     (N : Node_Id) return Node_Id;    -- Node2

   function Acts_As_Spec
     (N : Node_Id) return Boolean;    -- Flag4

   function Aggregate_Bounds
     (N : Node_Id) return Node_Id;    -- Node3

   function Aliased_Present
     (N : Node_Id) return Boolean;    -- Flag1

   function All_Present
     (N : Node_Id) return Boolean;    -- Flag1

   function Alternatives
     (N : Node_Id) return List_Id;    -- List4

   function Analyzed
     (N : Node_Id) return Boolean;    -- Flag15

   function Ancestor_Part
     (N : Node_Id) return Node_Id;    -- Node3

   function Array_Aggregate
     (N : Node_Id) return Node_Id;    -- Node4

   function Assignment_OK
     (N : Node_Id) return Boolean;    -- Flag1

   function Attribute_Name
     (N : Node_Id) return Name_Id;    -- Name2

   function Backwards_OK
     (N : Node_Id) return Boolean;    -- Flag6

   function Bad_Is_Detected
     (N : Node_Id) return Boolean;    -- Flag1

   function Body_Required
     (N : Node_Id) return Boolean;    -- Flag3

   function Box_Present
     (N : Node_Id) return Boolean;    -- Flag1

   function Cannot_Be_Constant
     (N : Node_Id) return Boolean;    -- Flag18

   function Char_Literal_Value
     (N : Node_Id) return Char_Code;  -- Char_Code2

   function Chars
     (N : Node_Id) return Name_Id;    -- Name1

   function Choice_Parameter
     (N : Node_Id) return Node_Id;    -- Node2

   function Choices
     (N : Node_Id) return List_Id;    -- List1

   function Cleanup_Call
     (N : Node_Id) return Node_Id;    -- Node5

   function Component_Associations
     (N : Node_Id) return List_Id;    -- List4

   function Component_Clauses
     (N : Node_Id) return List_Id;    -- List3

   function Component_Items
     (N : Node_Id) return List_Id;    -- List3

   function Component_List
     (N : Node_Id) return Node_Id;    -- Node1

   function Component_Name
     (N : Node_Id) return Node_Id;    -- Node1

   function Condition
     (N : Node_Id) return Node_Id;    -- Node5

   function Condition_Actions
     (N : Node_Id) return List_Id;    -- List3

   function Constant_Present
     (N : Node_Id) return Boolean;    -- Flag17

   function Constraint
     (N : Node_Id) return Node_Id;    -- Node3

   function Constraints
     (N : Node_Id) return List_Id;    -- List1

   function Context_Installed
     (N : Node_Id) return Boolean;    -- Flag3

   function Context_Items
     (N : Node_Id) return List_Id;    -- List1

   function Controlling_Argument
     (N : Node_Id) return Node_Id;    -- Node1

   function Conversion_OK
     (N : Node_Id) return Boolean;    -- Flag14

   function Corresponding_Body
     (N : Node_Id) return Node_Id;    -- Node5

   function Corresponding_Integer_Value
     (N : Node_Id) return Uint;       -- Uint4

   function Corresponding_Spec
     (N : Node_Id) return Node_Id;    -- Node5

   function Corresponding_Stub
     (N : Node_Id) return Node_Id;    -- Node3

   function Debug_Statement
     (N : Node_Id) return Node_Id;    -- Node3

   function Declarations
     (N : Node_Id) return List_Id;    -- List3

   function Default_Name
     (N : Node_Id) return Node_Id;    -- Node2

   function Defining_Identifier
     (N : Node_Id) return Entity_Id;  -- Node1

   function Defining_Unit_Name
     (N : Node_Id) return Node_Id;    -- Node1

   function Delay_Alternative
     (N : Node_Id) return Node_Id;    -- Node4

   function Delay_Statement
     (N : Node_Id) return Node_Id;    -- Node2

   function Delta_Expression
     (N : Node_Id) return Node_Id;    -- Node3

   function Digits_Expression
     (N : Node_Id) return Node_Id;    -- Node2

   function Discrete_Choices
     (N : Node_Id) return List_Id;    -- List4

   function Discrete_Range
     (N : Node_Id) return Node_Id;    -- Node4

   function Discrete_Subtype_Definition
     (N : Node_Id) return Node_Id;    -- Node4

   function Discrete_Subtype_Definitions
     (N : Node_Id) return List_Id;    -- List2

   function Discriminant_Specifications
     (N : Node_Id) return List_Id;    -- List4

   function Discriminant_Type
     (N : Node_Id) return Node_Id;    -- Node2

   function Do_Access_Check
     (N : Node_Id) return Boolean;    -- Flag11

   function Do_Accessibility_Check
     (N : Node_Id) return Boolean;    -- Flag3

   function Do_Discriminant_Check
     (N : Node_Id) return Boolean;    -- Flag3

   function Do_Division_Check
     (N : Node_Id) return Boolean;    -- Flag3

   function Do_Length_Check
     (N : Node_Id) return Boolean;    -- Flag4

   function Do_Overflow_Check
     (N : Node_Id) return Boolean;    -- Flag17

   function Do_Range_Check
     (N : Node_Id) return Boolean;    -- Flag9

   function Do_Storage_Check
     (N : Node_Id) return Boolean;    -- Flag17

   function Do_Tag_Check
     (N : Node_Id) return Boolean;    -- Flag3

   function Elaborate_Present
     (N : Node_Id) return Boolean;    -- Flag4

   function Elaborate_All_Present
     (N : Node_Id) return Boolean;    -- Flag1

   function Elaborate_Body_Present
     (N : Node_Id) return Boolean;    -- Flag7

   function Else_Actions
     (N : Node_Id) return List_Id;    -- List3

   function Else_Statements
     (N : Node_Id) return List_Id;    -- List4

   function Elsif_Parts
     (N : Node_Id) return List_Id;    -- List3

   function Enclosing_Variant
     (N : Node_Id) return Node_Id;    -- Node2

   function Entity
     (N : Node_Id) return Node_Id;    -- Node4

   function Entry_Body_Formal_Part
     (N : Node_Id) return Node_Id;    -- Node5

   function Entry_Call_Alternative
     (N : Node_Id) return Node_Id;    -- Node1

   function Entry_Call_Statement
     (N : Node_Id) return Node_Id;    -- Node1

   function Entry_Direct_Name
     (N : Node_Id) return Node_Id;    -- Node1

   function Entry_Index
     (N : Node_Id) return Node_Id;    -- Node5

   function Entry_Index_Specification
     (N : Node_Id) return Node_Id;    -- Node1

   function Error_Posted
     (N : Node_Id) return Boolean;    -- Flag13

   function Etype
     (N : Node_Id) return Node_Id;    -- Node5

   function Exception_Choices
     (N : Node_Id) return List_Id;    -- List4

   function Exception_Handlers
     (N : Node_Id) return List_Id;    -- List4

   function Explicit_Actual_Parameter
     (N : Node_Id) return Node_Id;    -- Node3

   function Explicit_Generic_Actual_Parameter
     (N : Node_Id) return Node_Id;    -- Node1

   function Expression
     (N : Node_Id) return Node_Id;    -- Node3

   function Expressions
     (N : Node_Id) return List_Id;    -- List1

   function First_Bit
     (N : Node_Id) return Node_Id;    -- Node3

   function First_Inlined_Subprogram
     (N : Node_Id) return Entity_Id;  -- Node5

   function First_Itype
     (N : Node_Id) return Entity_Id;  -- Node2

   function First_Name
     (N : Node_Id) return Boolean;    -- Flag5

   function First_Named_Actual
     (N : Node_Id) return Node_Id;    -- Node4

   function First_Real_Statement
     (N : Node_Id) return Node_Id;    -- Node2

   function First_Subtype_Link
     (N : Node_Id) return Entity_Id;  -- Node5

   function Float_Truncate
     (N : Node_Id) return Boolean;    -- Flag11

   function Following_Pragmas
     (N : Node_Id) return List_Id;    -- List3

   function Formal_Type_Definition
     (N : Node_Id) return Node_Id;    -- Node3

   function Forwards_OK
     (N : Node_Id) return Boolean;    -- Flag5

   function Generic_Associations
     (N : Node_Id) return List_Id;    -- List3

   function Generic_Formal_Declarations
     (N : Node_Id) return List_Id;    -- List3

   function Generic_Parent
     (N : Node_Id) return Node_Id;    -- Node5

   function Handled_Statement_Sequence
     (N : Node_Id) return Node_Id;    -- Node4

   function Has_Created_Identifier
     (N : Node_Id) return Boolean;    -- Flag1

   function Has_Dynamic_Itype
     (N : Node_Id) return Boolean;    -- Flag14

   function Has_No_Elab_Code
     (N : Node_Id) return Boolean;    -- Flag17

   function Has_No_Side_Effects
     (N : Node_Id) return Boolean;    -- Flag8

   function Has_Priority_Pragma
     (N : Node_Id) return Boolean;    -- Flag6

   function Has_Private_View
     (N : Node_Id) return Boolean;    -- Flag11

   function Has_Storage_Size_Pragma
     (N : Node_Id) return Boolean;    -- Flag5

   function High_Bound
     (N : Node_Id) return Node_Id;    -- Node2

   function Homonym
     (N : Node_Id) return Node_Id;    -- Node4

   function Identifier
     (N : Node_Id) return Node_Id;    -- Node1

   function Implicit_With
     (N : Node_Id) return Boolean;    -- Flag17

   function In_Present
     (N : Node_Id) return Boolean;    -- Flag1

   function Intval
     (N : Node_Id) return Uint;       -- Uint3

   function Is_Controlling_Actual
     (N : Node_Id) return Boolean;    -- Flag16

   function Is_Current_Instance
     (N : Node_Id) return Boolean;    -- Flag14

   function Is_Overloaded
     (N : Node_Id) return Boolean;    -- Flag5

   function Is_Static_Expression
     (N : Node_Id) return Boolean;    -- Flag6

   function Is_Task_Master
     (N : Node_Id) return Boolean;    -- Flag5

   function Iteration_Scheme
     (N : Node_Id) return Node_Id;    -- Node2

   function Left_Opnd
     (N : Node_Id) return Node_Id;    -- Node2

   function Label
     (N : Node_Id) return Node_Id;    -- Node2

   function Last_Bit
     (N : Node_Id) return Node_Id;    -- Node4

   function Last_Name
     (N : Node_Id) return Boolean;    -- Flag6

   function Library_Unit
     (N : Node_Id) return Node_Id;    -- Node4

   function Literals
     (N : Node_Id) return List_Id;    -- List1

   function Limited_Present
     (N : Node_Id) return Boolean;    -- Flag17

   function Loop_Parameter_Specification
     (N : Node_Id) return Node_Id;    -- Node1

   function Low_Bound
     (N : Node_Id) return Node_Id;    -- Node1

   function Mod_Clause
     (N : Node_Id) return Node_Id;    -- Node2

   function More_Ids
     (N : Node_Id) return Boolean;    -- Flag5

   function Name
     (N : Node_Id) return Node_Id;    -- Node2

   function Names
     (N : Node_Id) return List_Id;    -- List2

   function Next_Entity
     (N : Node_Id) return Node_Id;    -- Node2

   function Next_Interp
     (N : Node_Id) return Node_Id;    -- Node2

   function Next_Named_Actual
     (N : Node_Id) return Node_Id;    -- Node4

   function Next_Use_Clause
     (N : Node_Id) return Node_Id;    -- Node3

   function No_Default_Init
     (N : Node_Id) return Boolean;    -- Flag7

   function No_Defer
     (N : Node_Id) return Boolean;    -- Flag1

   function Null_Present
     (N : Node_Id) return Boolean;    -- Flag3

   function Null_Record_Present
     (N : Node_Id) return Boolean;    -- Flag17

   function Object_Definition
     (N : Node_Id) return Node_Id;    -- Node4

   function Object_Definition_Itypes
     (N : Node_Id) return Node_Id;    -- Node5

   function Others_Discrete_Choices
     (N : Node_Id) return List_Id;    -- List1

   function Out_Present
     (N : Node_Id) return Boolean;    -- Flag17

   function Parameter_Associations
     (N : Node_Id) return List_Id;    -- List3

   function Parameter_Specifications
     (N : Node_Id) return List_Id;    -- List3

   function Parameter_Type
     (N : Node_Id) return Node_Id;    -- Node2

   function Parent_Spec
     (N : Node_Id) return Node_Id;    -- Node4

   function Position
     (N : Node_Id) return Node_Id;    -- Node2

   function Pragma_Argument_Associations
     (N : Node_Id) return List_Id;    -- List2

   function Prefix
     (N : Node_Id) return Node_Id;    -- Node3

   function Prev_Ids
     (N : Node_Id) return Boolean;    -- Flag6

   function Private_Declarations
     (N : Node_Id) return List_Id;    -- List4

   function Private_Present
     (N : Node_Id) return Boolean;    -- Flag1

   function Procedure_To_Call
     (N : Node_Id) return Node_Id;    -- Node4

   function Proper_Body
     (N : Node_Id) return Node_Id;    -- Node1

   function Protected_Definition
     (N : Node_Id) return Node_Id;    -- Node3

   function Protected_Present
     (N : Node_Id) return Boolean;    -- Flag1

   function Raises_Constraint_Error
     (N : Node_Id) return Boolean;    -- Flag7

   function Range_Constraint
     (N : Node_Id) return Node_Id;    -- Node4

   function Range_Expression
     (N : Node_Id) return Node_Id;    -- Node4

   function Realval
     (N : Node_Id) return Ureal;      -- Ureal3

   function Real_Range_Specification
     (N : Node_Id) return Node_Id;    -- Node4

   function Record_Extension_Part
     (N : Node_Id) return Node_Id;    -- Node3

   function Redundant_Use
     (N : Node_Id) return Boolean;    -- Flag3

   function Return_Type
     (N : Node_Id) return Node_Id;    -- Node2

   function Reverse_Present
     (N : Node_Id) return Boolean;    -- Flag1

   function Right_Opnd
     (N : Node_Id) return Node_Id;    -- Node3

   function Rounded_Result
     (N : Node_Id) return Boolean;    -- Flag12

   function Scope
     (N : Node_Id) return Node_Id;    -- Node3

   function Select_Alternatives
     (N : Node_Id) return List_Id;    -- List1

   function Selector_Name
     (N : Node_Id) return Node_Id;    -- Node2

   function Selector_Names
     (N : Node_Id) return List_Id;    -- List1

   function Specification
     (N : Node_Id) return Node_Id;    -- Node1

   function Statements
     (N : Node_Id) return List_Id;    -- List3

   function Storage_Pool
     (N : Node_Id) return Node_Id;    -- Node1

   function Strval
     (N : Node_Id) return String_Id;  -- Str3

   function Subtype_Indication
     (N : Node_Id) return Node_Id;    -- Node5

   function Subtype_Mark
     (N : Node_Id) return Node_Id;    -- Node4

   function Subtype_Marks
     (N : Node_Id) return List_Id;    -- List2

   function Tagged_Present
     (N : Node_Id) return Boolean;    -- Flag1

   function Task_Definition
     (N : Node_Id) return Node_Id;    -- Node3

   function Then_Actions
     (N : Node_Id) return List_Id;    -- List2

   function Then_Statements
     (N : Node_Id) return List_Id;    -- List2

   function Treat_Fixed_As_Integer
     (N : Node_Id) return Boolean;    -- Flag14

   function Triggering_Alternative
     (N : Node_Id) return Node_Id;    -- Node1

   function Triggering_Statement
     (N : Node_Id) return Node_Id;    -- Node1

   function TSS_Elist
     (N : Node_Id) return Elist_Id;   -- Elist3

   function Type_Definition
     (N : Node_Id) return Node_Id;    -- Node3

   function Unit
     (N : Node_Id) return Node_Id;    -- Node2

   function Unknown_Discriminants_Present
     (N : Node_Id) return Boolean;    -- Flag3

   function Variant_Part
     (N : Node_Id) return Node_Id;    -- Node4

   function Variants
     (N : Node_Id) return List_Id;    -- List1

   function Visible_Declarations
     (N : Node_Id) return List_Id;    -- List2

   --  End functions (note used by xsinfo utility program to end processing)

   ----------------------------
   -- Node Update Procedures --
   ----------------------------

   --  These are the corresponding node update routines, which again provide
   --  a high level logical access with type checking. In addition to setting
   --  the indicated field of the node N to the given Val, in the case of
   --  tree pointers (List1-4), the parent pointer of the Val node is set to
   --  point back to node N. This automates the setting of the parent pointer.

   procedure Set_Abort_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Abortable_Part
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Abstract_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag4

   procedure Set_Accept_Statement
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Actions
     (N : Node_Id; Val : List_Id);            -- List1

   procedure Set_Activation_Chain_Entity
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Acts_As_Spec
     (N : Node_Id; Val : Boolean := True);    -- Flag4

   procedure Set_Aggregate_Bounds
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Aliased_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_All_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Alternatives
     (N : Node_Id; Val : List_Id);            -- List4

   procedure Set_Analyzed
     (N : Node_Id; Val : Boolean := True);    -- Flag15

   procedure Set_Ancestor_Part
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Array_Aggregate
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Assignment_OK
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Attribute_Name
     (N : Node_Id; Val : Name_Id);            -- Name2

   procedure Set_Backwards_OK
     (N : Node_Id; Val : Boolean := True);    -- Flag6

   procedure Set_Bad_Is_Detected
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Body_Required
     (N : Node_Id; Val : Boolean := True);    -- Flag3

   procedure Set_Box_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Cannot_Be_Constant
     (N : Node_Id; Val : Boolean := True);    -- Flag18

   procedure Set_Char_Literal_Value
     (N : Node_Id; Val : Char_Code);          -- Char_Code2

   procedure Set_Chars
     (N : Node_Id; Val : Name_Id);            -- Name1

   procedure Set_Choice_Parameter
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Choices
     (N : Node_Id; Val : List_Id);            -- List1

   procedure Set_Cleanup_Call
     (N : Node_Id; Val : Node_Id);            -- Node5

   procedure Set_Component_Associations
     (N : Node_Id; Val : List_Id);            -- List4

   procedure Set_Component_Clauses
     (N : Node_Id; Val : List_Id);            -- List3

   procedure Set_Component_Items
     (N : Node_Id; Val : List_Id);            -- List3

   procedure Set_Component_List
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Component_Name
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Condition
     (N : Node_Id; Val : Node_Id);            -- Node5

   procedure Set_Condition_Actions
     (N : Node_Id; Val : List_Id);            -- List3

   procedure Set_Constant_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag17

   procedure Set_Constraint
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Constraints
     (N : Node_Id; Val : List_Id);            -- List1

   procedure Set_Context_Installed
     (N : Node_Id; Val : Boolean := True);    -- Flag3

   procedure Set_Context_Items
     (N : Node_Id; Val : List_Id);            -- List1

   procedure Set_Controlling_Argument
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Conversion_OK
     (N : Node_Id; Val : Boolean := True);    -- Flag14

   procedure Set_Corresponding_Body
     (N : Node_Id; Val : Node_Id);            -- Node5

   procedure Set_Corresponding_Integer_Value
     (N : Node_Id; Val : Uint);               -- Uint4

   procedure Set_Corresponding_Spec
     (N : Node_Id; Val : Node_Id);            -- Node5

   procedure Set_Corresponding_Stub
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Debug_Statement
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Declarations
     (N : Node_Id; Val : List_Id);            -- List3

   procedure Set_Default_Name
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Defining_Identifier
     (N : Node_Id; Val : Entity_Id);          -- Node1

   procedure Set_Defining_Unit_Name
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Delay_Alternative
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Delay_Statement
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Delta_Expression
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Digits_Expression
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Discrete_Choices
     (N : Node_Id; Val : List_Id);            -- List4

   procedure Set_Discrete_Range
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Discrete_Subtype_Definition
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Discrete_Subtype_Definitions
     (N : Node_Id; Val : List_Id);            -- List2

   procedure Set_Discriminant_Specifications
     (N : Node_Id; Val : List_Id);            -- List4

   procedure Set_Discriminant_Type
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Do_Access_Check
     (N : Node_Id; Val : Boolean := True);    -- Flag11

   procedure Set_Do_Accessibility_Check
     (N : Node_Id; Val : Boolean := True);    -- Flag3

   procedure Set_Do_Discriminant_Check
     (N : Node_Id; Val : Boolean := True);    -- Flag3

   procedure Set_Do_Division_Check
     (N : Node_Id; Val : Boolean := True);    -- Flag3

   procedure Set_Do_Length_Check
     (N : Node_Id; Val : Boolean := True);    -- Flag4

   procedure Set_Do_Overflow_Check
     (N : Node_Id; Val : Boolean := True);    -- Flag17

   procedure Set_Do_Range_Check
     (N : Node_Id; Val : Boolean := True);    -- Flag9

   procedure Set_Do_Storage_Check
     (N : Node_Id; Val : Boolean := True);    -- Flag17

   procedure Set_Do_Tag_Check
     (N : Node_Id; Val : Boolean := True);    -- Flag3

   procedure Set_Elaborate_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag4

   procedure Set_Elaborate_All_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Elaborate_Body_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag7

   procedure Set_Else_Actions
     (N : Node_Id; Val : List_Id);            -- List3

   procedure Set_Else_Statements
     (N : Node_Id; Val : List_Id);            -- List4

   procedure Set_Elsif_Parts
     (N : Node_Id; Val : List_Id);            -- List3

   procedure Set_Enclosing_Variant
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Entity
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Entry_Body_Formal_Part
     (N : Node_Id; Val : Node_Id);            -- Node5

   procedure Set_Entry_Call_Alternative
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Entry_Call_Statement
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Entry_Direct_Name
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Entry_Index
     (N : Node_Id; Val : Node_Id);            -- Node5

   procedure Set_Entry_Index_Specification
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Error_Posted
     (N : Node_Id; Val : Boolean := True);    -- Flag13

   procedure Set_Etype
     (N : Node_Id; Val : Node_Id);            -- Node5

   procedure Set_Exception_Choices
     (N : Node_Id; Val : List_Id);            -- List4

   procedure Set_Exception_Handlers
     (N : Node_Id; Val : List_Id);            -- List4

   procedure Set_Explicit_Actual_Parameter
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Explicit_Generic_Actual_Parameter
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Expression
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Expressions
     (N : Node_Id; Val : List_Id);            -- List1

   procedure Set_First_Bit
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_First_Inlined_Subprogram
     (N : Node_Id; Val : Entity_Id);          -- Node5

   procedure Set_First_Itype
     (N : Node_Id; Val : Entity_Id);          -- Node2

   procedure Set_First_Name
     (N : Node_Id; Val : Boolean := True);    -- Flag5

   procedure Set_First_Named_Actual
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_First_Real_Statement
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_First_Subtype_Link
     (N : Node_Id; Val : Entity_Id);          -- Node5

   procedure Set_Float_Truncate
     (N : Node_Id; Val : Boolean := True);    -- Flag11

   procedure Set_Following_Pragmas
     (N : Node_Id; Val : List_Id);            -- List3

   procedure Set_Formal_Type_Definition
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Forwards_OK
     (N : Node_Id; Val : Boolean := True);    -- Flag5

   procedure Set_Generic_Associations
     (N : Node_Id; Val : List_Id);            -- List3

   procedure Set_Generic_Formal_Declarations
     (N : Node_Id; Val : List_Id);            -- List3

   procedure Set_Generic_Parent
     (N : Node_Id; Val : Node_Id);            -- Node5

   procedure Set_Handled_Statement_Sequence
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Has_Created_Identifier
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Has_Dynamic_Itype
     (N : Node_Id; Val : Boolean := True);    -- Flag14

   procedure Set_Has_No_Elab_Code
     (N : Node_Id; Val : Boolean := True);    -- Flag17

   procedure Set_Has_No_Side_Effects
     (N : Node_Id; Val : Boolean := True);    -- Flag8

   procedure Set_Has_Priority_Pragma
     (N : Node_Id; Val : Boolean := True);    -- Flag6

   procedure Set_Has_Private_View
     (N : Node_Id; Val : Boolean := True);    -- Flag11

   procedure Set_Has_Storage_Size_Pragma
     (N : Node_Id; Val : Boolean := True);    -- Flag5

   procedure Set_High_Bound
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Homonym
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Identifier
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Implicit_With
     (N : Node_Id; Val : Boolean := True);    -- Flag17

   procedure Set_In_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Intval
     (N : Node_Id; Val : Uint);               -- Uint3

   procedure Set_Is_Controlling_Actual
     (N : Node_Id; Val : Boolean := True);    -- Flag16

   procedure Set_Is_Current_Instance
     (N : Node_Id; Val : Boolean := True);    -- Flag14

   procedure Set_Is_Overloaded
     (N : Node_Id; Val : Boolean := True);    -- Flag5

   procedure Set_Is_Static_Expression
     (N : Node_Id; Val : Boolean := True);    -- Flag6

   procedure Set_Is_Task_Master
     (N : Node_Id; Val : Boolean := True);    -- Flag5

   procedure Set_Iteration_Scheme
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Label
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Last_Bit
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Last_Name
     (N : Node_Id; Val : Boolean := True);    -- Flag6

   procedure Set_Library_Unit
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Left_Opnd
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Literals
     (N : Node_Id; Val : List_Id);            -- List1

   procedure Set_Limited_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag17

   procedure Set_Loop_Parameter_Specification
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Low_Bound
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Mod_Clause
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_More_Ids
     (N : Node_Id; Val : Boolean := True);    -- Flag5

   procedure Set_Name
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Names
     (N : Node_Id; Val : List_Id);            -- List2

   procedure Set_Next_Entity
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Next_Interp
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Next_Named_Actual
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Next_Use_Clause
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_No_Default_Init
     (N : Node_Id; Val : Boolean := True);    -- Flag7

   procedure Set_No_Defer
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Null_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag3

   procedure Set_Null_Record_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag17

   procedure Set_Object_Definition
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Object_Definition_Itypes
     (N : Node_Id; Val : Node_Id);            -- Node5

   procedure Set_Others_Discrete_Choices
     (N : Node_Id; Val : List_Id);            -- List1

   procedure Set_Out_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag17

   procedure Set_Parameter_Associations
     (N : Node_Id; Val : List_Id);            -- List3

   procedure Set_Parameter_Specifications
     (N : Node_Id; Val : List_Id);            -- List3

   procedure Set_Parameter_Type
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Parent_Spec
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Position
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Pragma_Argument_Associations
     (N : Node_Id; Val : List_Id);            -- List2

   procedure Set_Prefix
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Prev_Ids
     (N : Node_Id; Val : Boolean := True);    -- Flag6

   procedure Set_Private_Declarations
     (N : Node_Id; Val : List_Id);            -- List4

   procedure Set_Private_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Procedure_To_Call
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Proper_Body
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Protected_Definition
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Protected_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Raises_Constraint_Error
     (N : Node_Id; Val : Boolean := True);    -- Flag7

   procedure Set_Range_Constraint
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Range_Expression
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Realval
     (N : Node_Id; Val : Ureal);              -- Ureal3

   procedure Set_Real_Range_Specification
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Record_Extension_Part
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Redundant_Use
     (N : Node_Id; Val : Boolean := True);    -- Flag3

   procedure Set_Return_Type
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Reverse_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Right_Opnd
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Rounded_Result
     (N : Node_Id; Val : Boolean := True);    -- Flag12

   procedure Set_Scope
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Select_Alternatives
     (N : Node_Id; Val : List_Id);            -- List1

   procedure Set_Selector_Name
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Selector_Names
     (N : Node_Id; Val : List_Id);            -- List1

   procedure Set_Specification
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Statements
     (N : Node_Id; Val : List_Id);            -- List3

   procedure Set_Storage_Pool
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Strval
     (N : Node_Id; Val : String_Id);          -- Str3

   procedure Set_Subtype_Indication
     (N : Node_Id; Val : Node_Id);            -- Node5

   procedure Set_Subtype_Mark
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Subtype_Marks
     (N : Node_Id; Val : List_Id);            -- List2

   procedure Set_Tagged_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag1

   procedure Set_Task_Definition
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Then_Actions
     (N : Node_Id; Val : List_Id);            -- List2

   procedure Set_Then_Statements
     (N : Node_Id; Val : List_Id);            -- List2

   procedure Set_Treat_Fixed_As_Integer
     (N : Node_Id; Val : Boolean := True);    -- Flag14

   procedure Set_Triggering_Alternative
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_Triggering_Statement
     (N : Node_Id; Val : Node_Id);            -- Node1

   procedure Set_TSS_Elist
     (N : Node_Id; Val : Elist_Id);           -- Elist3

   procedure Set_Type_Definition
     (N : Node_Id; Val : Node_Id);            -- Node3

   procedure Set_Unit
     (N : Node_Id; Val : Node_Id);            -- Node2

   procedure Set_Unknown_Discriminants_Present
     (N : Node_Id; Val : Boolean := True);    -- Flag3

   procedure Set_Variant_Part
     (N : Node_Id; Val : Node_Id);            -- Node4

   procedure Set_Variants
     (N : Node_Id; Val : List_Id);            -- List1

   procedure Set_Visible_Declarations
     (N : Node_Id; Val : List_Id);            -- List2

   --------------------
   -- Inline Pragmas --
   --------------------

   pragma Inline (Abort_Present);
   pragma Inline (Abortable_Part);
   pragma Inline (Abstract_Present);
   pragma Inline (Accept_Statement);
   pragma Inline (Actions);
   pragma Inline (Activation_Chain_Entity);
   pragma Inline (Acts_As_Spec);
   pragma Inline (Aggregate_Bounds);
   pragma Inline (Aliased_Present);
   pragma Inline (All_Present);
   pragma Inline (Alternatives);
   pragma Inline (Analyzed);
   pragma Inline (Ancestor_Part);
   pragma Inline (Array_Aggregate);
   pragma Inline (Assignment_OK);
   pragma Inline (Attribute_Name);
   pragma Inline (Backwards_OK);
   pragma Inline (Bad_Is_Detected);
   pragma Inline (Body_Required);
   pragma Inline (Box_Present);
   pragma Inline (Cannot_Be_Constant);
   pragma Inline (Char_Literal_Value);
   pragma Inline (Chars);
   pragma Inline (Choice_Parameter);
   pragma Inline (Choices);
   pragma Inline (Cleanup_Call);
   pragma Inline (Component_Associations);
   pragma Inline (Component_Clauses);
   pragma Inline (Component_Items);
   pragma Inline (Component_List);
   pragma Inline (Component_Name);
   pragma Inline (Condition);
   pragma Inline (Condition_Actions);
   pragma Inline (Constant_Present);
   pragma Inline (Constraint);
   pragma Inline (Constraints);
   pragma Inline (Context_Installed);
   pragma Inline (Context_Items);
   pragma Inline (Controlling_Argument);
   pragma Inline (Conversion_OK);
   pragma Inline (Corresponding_Body);
   pragma Inline (Corresponding_Integer_Value);
   pragma Inline (Corresponding_Spec);
   pragma Inline (Corresponding_Stub);
   pragma Inline (Debug_Statement);
   pragma Inline (Declarations);
   pragma Inline (Default_Name);
   pragma Inline (Defining_Identifier);
   pragma Inline (Defining_Unit_Name);
   pragma Inline (Delay_Alternative);
   pragma Inline (Delay_Statement);
   pragma Inline (Delta_Expression);
   pragma Inline (Digits_Expression);
   pragma Inline (Discrete_Choices);
   pragma Inline (Discrete_Range);
   pragma Inline (Discrete_Subtype_Definition);
   pragma Inline (Discrete_Subtype_Definitions);
   pragma Inline (Discriminant_Specifications);
   pragma Inline (Discriminant_Type);
   pragma Inline (Do_Access_Check);
   pragma Inline (Do_Accessibility_Check);
   pragma Inline (Do_Discriminant_Check);
   pragma Inline (Do_Length_Check);
   pragma Inline (Do_Division_Check);
   pragma Inline (Do_Overflow_Check);
   pragma Inline (Do_Range_Check);
   pragma Inline (Do_Storage_Check);
   pragma Inline (Do_Tag_Check);
   pragma Inline (Elaborate_Present);
   pragma Inline (Elaborate_All_Present);
   pragma Inline (Elaborate_Body_Present);
   pragma Inline (Else_Actions);
   pragma Inline (Else_Statements);
   pragma Inline (Elsif_Parts);
   pragma Inline (Enclosing_Variant);
   pragma Inline (Entity);
   pragma Inline (Entry_Body_Formal_Part);
   pragma Inline (Entry_Call_Alternative);
   pragma Inline (Entry_Call_Statement);
   pragma Inline (Entry_Direct_Name);
   pragma Inline (Entry_Index);
   pragma Inline (Entry_Index_Specification);
   pragma Inline (Error_Posted);
   pragma Inline (Etype);
   pragma Inline (Exception_Choices);
   pragma Inline (Exception_Handlers);
   pragma Inline (Explicit_Actual_Parameter);
   pragma Inline (Explicit_Generic_Actual_Parameter);
   pragma Inline (Expression);
   pragma Inline (Expressions);
   pragma Inline (First_Bit);
   pragma Inline (First_Inlined_Subprogram);
   pragma Inline (First_Itype);
   pragma Inline (First_Name);
   pragma Inline (First_Named_Actual);
   pragma Inline (First_Real_Statement);
   pragma Inline (First_Subtype_Link);
   pragma Inline (Float_Truncate);
   pragma Inline (Following_Pragmas);
   pragma Inline (Formal_Type_Definition);
   pragma Inline (Forwards_OK);
   pragma Inline (Generic_Associations);
   pragma Inline (Generic_Formal_Declarations);
   pragma Inline (Generic_Parent);
   pragma Inline (Handled_Statement_Sequence);
   pragma Inline (Has_Created_Identifier);
   pragma Inline (Has_Dynamic_Itype);
   pragma Inline (Has_No_Elab_Code);
   pragma Inline (Has_No_Side_Effects);
   pragma Inline (Has_Priority_Pragma);
   pragma Inline (Has_Private_View);
   pragma Inline (Has_Storage_Size_Pragma);
   pragma Inline (High_Bound);
   pragma Inline (Homonym);
   pragma Inline (Identifier);
   pragma Inline (Implicit_With);
   pragma Inline (In_Present);
   pragma Inline (Intval);
   pragma Inline (Is_Controlling_Actual);
   pragma Inline (Is_Current_Instance);
   pragma Inline (Is_Overloaded);
   pragma Inline (Is_Static_Expression);
   pragma Inline (Is_Task_Master);
   pragma Inline (Iteration_Scheme);
   pragma Inline (Label);
   pragma Inline (Last_Bit);
   pragma Inline (Last_Name);
   pragma Inline (Library_Unit);
   pragma Inline (Left_Opnd);
   pragma Inline (Limited_Present);
   pragma Inline (Literals);
   pragma Inline (Loop_Parameter_Specification);
   pragma Inline (Low_Bound);
   pragma Inline (Mod_Clause);
   pragma Inline (More_Ids);
   pragma Inline (Name);
   pragma Inline (Names);
   pragma Inline (Next_Entity);
   pragma Inline (Next_Interp);
   pragma Inline (Next_Named_Actual);
   pragma Inline (Next_Use_Clause);
   pragma Inline (No_Default_Init);
   pragma Inline (No_Defer);
   pragma Inline (Null_Present);
   pragma Inline (Null_Record_Present);
   pragma Inline (Object_Definition);
   pragma Inline (Object_Definition_Itypes);
   pragma Inline (Others_Discrete_Choices);
   pragma Inline (Out_Present);
   pragma Inline (Parameter_Associations);
   pragma Inline (Parameter_Specifications);
   pragma Inline (Parameter_Type);
   pragma Inline (Parent_Spec);
   pragma Inline (Position);
   pragma Inline (Pragma_Argument_Associations);
   pragma Inline (Prefix);
   pragma Inline (Prev_Ids);
   pragma Inline (Private_Declarations);
   pragma Inline (Private_Present);
   pragma Inline (Procedure_To_Call);
   pragma Inline (Proper_Body);
   pragma Inline (Protected_Definition);
   pragma Inline (Protected_Present);
   pragma Inline (Raises_Constraint_Error);
   pragma Inline (Range_Constraint);
   pragma Inline (Range_Expression);
   pragma Inline (Realval);
   pragma Inline (Real_Range_Specification);
   pragma Inline (Record_Extension_Part);
   pragma Inline (Redundant_Use);
   pragma Inline (Return_Type);
   pragma Inline (Reverse_Present);
   pragma Inline (Right_Opnd);
   pragma Inline (Rounded_Result);
   pragma Inline (Scope);
   pragma Inline (Select_Alternatives);
   pragma Inline (Selector_Name);
   pragma Inline (Selector_Names);
   pragma Inline (Specification);
   pragma Inline (Statements);
   pragma Inline (Storage_Pool);
   pragma Inline (Strval);
   pragma Inline (Subtype_Indication);
   pragma Inline (Subtype_Mark);
   pragma Inline (Subtype_Marks);
   pragma Inline (Tagged_Present);
   pragma Inline (Task_Definition);
   pragma Inline (Then_Actions);
   pragma Inline (Then_Statements);
   pragma Inline (Triggering_Alternative);
   pragma Inline (Triggering_Statement);
   pragma Inline (Treat_Fixed_As_Integer);
   pragma Inline (TSS_Elist);
   pragma Inline (Type_Definition);
   pragma Inline (Unit);
   pragma Inline (Unknown_Discriminants_Present);
   pragma Inline (Variant_Part);
   pragma Inline (Variants);
   pragma Inline (Visible_Declarations);

   pragma Inline (Set_Analyzed);
   pragma Inline (Set_Entity);
   pragma Inline (Set_Error_Posted);
   pragma Inline (Set_Etype);

end Sinfo;