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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S E M _ U T I L --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 1992-2014, Free Software Foundation, Inc. --
10 -- --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
20 -- --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
23 -- --
24 ------------------------------------------------------------------------------
26 -- Package containing utility procedures used throughout the semantics
39 -- Given a type that implements interfaces look for its associated
40 -- definition node and return its list of interfaces.
43 -- Add A to the list of access types to process when expanding the
44 -- freeze node of E.
47 -- Given a block statement N, generate an internal E_Block label and make
48 -- it the identifier of the block. Id denotes the generated entity. If the
49 -- block already has an identifier, Id returns the entity of its label.
52 -- Add pragma Prag to the contract of an entry, a package [body], a
53 -- subprogram [body] or variable denoted by Id. The following are valid
54 -- pragmas:
55 -- Abstract_States
56 -- Async_Readers
57 -- Async_Writers
58 -- Contract_Cases
59 -- Depends
60 -- Effective_Reads
61 -- Effective_Writes
62 -- Global
63 -- Initial_Condition
64 -- Initializes
65 -- Part_Of
66 -- Postcondition
67 -- Precondition
68 -- Refined_Depends
69 -- Refined_Global
70 -- Refined_Post
71 -- Refined_States
72 -- Test_Case
75 -- These procedures adds a declaration N at the library level, to be
76 -- elaborated before any other code in the unit. It is used for example
77 -- for the entity that marks whether a unit has been elaborated. The
78 -- declaration is added to the Declarations list of the Aux_Decls_Node
79 -- for the current unit. The declarations are added in the current scope,
80 -- so the caller should push a new scope as required before the call.
83 -- Given two types, returns True if we are in Allow_Integer_Address mode
84 -- and one of the types is (a descendent of) System.Address (and this type
85 -- is private), and the other type is any integer type.
90 -- Returns True if the value of V is the word size of an addressable
91 -- factor of the word size (typically 8, 16, 32 or 64).
94 -- If the alignment of the type or object E is currently known to the
95 -- compiler, then this function returns the alignment value in bits.
96 -- Otherwise Uint_0 is returned, indicating that the alignment of the
97 -- entity is not yet known to the compiler.
100 -- If the parent of the operation is declared in the visible part of
101 -- the current scope, the inherited operation is visible even though the
102 -- derived type that inherits the operation may be completed in the private
103 -- part of the current package.
105 procedure Apply_Compile_Time_Constraint_Error
114 -- N is a subexpression which will raise constraint error when evaluated
115 -- at runtime. Msg is a message that explains the reason for raising the
116 -- exception. The last character is ? if the message is always a warning,
117 -- even in Ada 95, and is not a ? if the message represents an illegality
118 -- (because of violation of static expression rules) in Ada 95 (but not
119 -- in Ada 83). Typically this routine posts all messages at the Sloc of
120 -- node N. However, if Loc /= No_Location, Loc is the Sloc used to output
121 -- the message. After posting the appropriate message, and if the flag
122 -- Rep is set, this routine replaces the expression with an appropriate
123 -- N_Raise_Constraint_Error node using the given Reason code. This node
124 -- is then marked as being static if the original node is static, but
125 -- sets the flag Raises_Constraint_Error, preventing further evaluation.
126 -- The error message may contain a } or & insertion character. This
127 -- normally references Etype (N), unless the Ent argument is given
128 -- explicitly, in which case it is used instead. The type of the raise
129 -- node that is built is normally Etype (N), but if the Typ parameter
130 -- is present, this is used instead. Warn is normally False. If it is
131 -- True then the message is treated as a warning even though it does
132 -- not end with a ? (this is used when the caller wants to parameterize
133 -- whether an error or warning is given).
136 -- Given the entity of an abstract state or a variable, determine whether
137 -- Id is subject to external property Async_Readers and if it is, the
138 -- related expression evaluates to True.
141 -- Given the entity of an abstract state or a variable, determine whether
142 -- Id is subject to external property Async_Writers and if it is, the
143 -- related expression evaluates to True.
146 -- If at the point of declaration an array type has a private or limited
147 -- component, several array operations are not avaiable on the type, and
148 -- the array type is flagged accordingly. If in the immediate scope of
149 -- the array type the component becomes non-private or non-limited, these
150 -- operations become avaiable. This can happen if the scopes of both types
151 -- are open, and the scope of the array is not outside the scope of the
152 -- component.
154 procedure Bad_Attribute
158 -- Called when node N is expected to contain a valid attribute name, and
159 -- Nam is found instead. If Warn is set True this is a warning, else this
160 -- is an error.
162 procedure Bad_Predicated_Subtype_Use
167 -- This is called when Typ, a predicated subtype, is used in a context
168 -- which does not allow the use of a predicated subtype. Msg is passed to
169 -- Error_Msg_FE to output an appropriate message using N as the location,
170 -- and Typ as the entity. The caller must set up any insertions other than
171 -- the & for the type itself. Note that if Typ is a generic actual type,
172 -- then the message will be output as a warning, and a raise Program_Error
173 -- is inserted using Insert_Action with node N as the insertion point. Node
174 -- N also supplies the source location for construction of the raise node.
175 -- If Typ does not have any predicates, the call has no effect. Set flag
176 -- Suggest_Static when the context warrants an advice on how to avoid the
177 -- use error.
179 function Bad_Unordered_Enumeration_Reference
182 -- Node N contains a potentially dubious reference to type T, either an
183 -- explicit comparison, or an explicit range. This function returns True
184 -- if the type T is an enumeration type for which No pragma Order has been
185 -- given, and the reference N is not in the same extended source unit as
186 -- the declaration of T.
188 function Build_Actual_Subtype
191 -- Build an anonymous subtype for an entity or expression, using the
192 -- bounds of the entity or the discriminants of the enclosing record.
193 -- T is the type for which the actual subtype is required, and N is either
194 -- a defining identifier, or any subexpression.
196 function Build_Actual_Subtype_Of_Component
199 -- Determine whether a selected component has a type that depends on
200 -- discriminants, and build actual subtype for it if so.
202 function Build_Default_Subtype
205 -- If T is an unconstrained type with defaulted discriminants, build a
206 -- subtype constrained by the default values, insert the subtype
207 -- declaration in the tree before N, and return the entity of that
208 -- subtype. Otherwise, simply return T.
210 function Build_Discriminal_Subtype_Of_Component
212 -- Determine whether a record component has a type that depends on
213 -- discriminants, and build actual subtype for it if so.
216 -- Given a compilation unit node N, allocate an elaboration counter for
217 -- the compilation unit, and install it in the Elaboration_Entity field
218 -- of Spec_Id, the entity for the compilation unit.
220 procedure Build_Explicit_Dereference
223 -- AI05-139: Names with implicit dereference. If the expression N is a
224 -- reference type and the context imposes the corresponding designated
225 -- type, convert N into N.Disc.all. Such expressions are always over-
226 -- loaded with both interpretations, and the dereference interpretation
227 -- carries the name of the reference discriminant.
230 -- Returns True if the expression cannot possibly raise Constraint_Error.
231 -- The response is conservative in the sense that a result of False does
232 -- not necessarily mean that CE could be raised, but a response of True
233 -- means that for sure CE cannot be raised.
235 procedure Check_Dynamically_Tagged_Expression
239 -- Check wrong use of dynamically tagged expression
241 procedure Check_Expression_Against_Static_Predicate
244 -- Determine whether an arbitrary expression satisfies the static predicate
245 -- of a type. The routine does nothing if Expr is not known at compile time
246 -- or Typ lacks a static predicate, otherwise it may emit a warning if the
247 -- expression is prohibited by the predicate.
250 -- Verify that the full declaration of type T has been seen. If not, place
251 -- error message on node N. Used in object declarations, type conversions
252 -- and qualified expressions.
255 -- (Ada 2012): If the construct N has two or more direct constituents that
256 -- are names or expressions whose evaluation may occur in an arbitrary
257 -- order, at least one of which contains a function call with an in out or
258 -- out parameter, then the construct is legal only if: for each name that
259 -- is passed as a parameter of mode in out or out to some inner function
260 -- call C2 (not including the construct N itself), there is no other name
261 -- anywhere within a direct constituent of the construct C other than
262 -- the one containing C2, that is known to refer to the same object (RM
263 -- 6.4.1(6.17/3)).
266 -- AI05-139-2: Accessors and iterators for containers. This procedure
267 -- checks whether T is a reference type, and if so it adds an interprettion
268 -- to Expr whose type is the designated type of the reference_discriminant.
271 -- Within a protected function, the current object is a constant, and
272 -- internal calls to a procedure or entry are illegal. Similarly, other
273 -- uses of a protected procedure in a renaming or a generic instantiation
274 -- in the context of a protected function are illegal (AI05-0225).
276 procedure Check_Later_Vs_Basic_Declarations
279 -- If During_Parsing is True, check for misplacement of later vs basic
280 -- declarations in Ada 83. If During_Parsing is False, and the SPARK
281 -- restriction is set, do the same: although SPARK 95 removes the
282 -- distinction between initial and later declarative items, the distinction
283 -- remains in the Examiner (JB01-005). Note that the Examiner does not
284 -- count package declarations in later declarative items.
287 -- Check whether Ent denotes an entity declared in an uplevel scope, which
288 -- is accessed inside a nested procedure, and set Has_Up_Level_Access flag
289 -- accordingly. This is currently only enabled for VM_Target /= No_VM.
292 -- Determine whether object or state Id introduces a hidden state. If this
293 -- is the case, emit an error.
296 -- N is one of the statement forms that is a potentially blocking
297 -- operation. If it appears within a protected action, emit warning.
299 procedure Check_Result_And_Post_State
302 -- Determine whether pragma Prag mentions attribute 'Result and whether
303 -- the pragma contains an expression that evaluates differently in pre-
304 -- and post-state. Prag is a [refined] postcondition or a contract-cases
305 -- pragma. Result_Seen is set when the pragma mentions attribute 'Result.
308 -- Given a generic package [body] or a generic subprogram [body], inspect
309 -- the aspect specifications (if any) and flag SPARK_Mode as illegal.
311 procedure Check_Unprotected_Access
314 -- Check whether the expression is a pointer to a protected component,
315 -- and the context is external to the protected operation, to warn against
316 -- a possible unlocked access to data.
319 -- Check that this the target is OpenVMS, and if so, return with no effect,
320 -- otherwise post an error noting this can only be used with OpenVMS ports.
321 -- The argument is the construct in question and is used to post the error
322 -- message.
324 procedure Collect_Interfaces
329 -- Ada 2005 (AI-251): Collect whole list of abstract interfaces that are
330 -- directly or indirectly implemented by T. Exclude_Parents is used to
331 -- avoid the addition of inherited interfaces to the generated list.
332 -- Use_Full_View is used to collect the interfaces using the full-view
333 -- (if available).
335 procedure Collect_Interface_Components
338 -- Ada 2005 (AI-251): Collect all the tag components associated with the
339 -- secondary dispatch tables of a tagged type.
341 procedure Collect_Interfaces_Info
346 -- Ada 2005 (AI-251): Collect all the interfaces associated with T plus
347 -- the record component and tag associated with each of these interfaces.
348 -- On exit Ifaces_List, Components_List and Tags_List have the same number
349 -- of elements, and elements at the same position on these tables provide
350 -- information on the same interface type.
352 procedure Collect_Parents
356 -- Collect all the parents of Typ. Use_Full_View is used to collect them
357 -- using the full-view of private parents (if available).
360 -- Called upon type derivation and extension. We scan the declarative part
361 -- in which the type appears, and collect subprograms that have one
362 -- subsidiary subtype of the type. These subprograms can only appear after
363 -- the type itself.
365 function Compile_Time_Constraint_Error
371 -- This is similar to Apply_Compile_Time_Constraint_Error in that it
372 -- generates a warning (or error) message in the same manner, but it does
373 -- not replace any nodes. For convenience, the function always returns its
374 -- first argument. The message is a warning if the message ends with ?, or
375 -- we are operating in Ada 83 mode, or the Warn parameter is set to True.
378 -- Sets the Has_Delayed_Freeze flag of New if the Delayed_Freeze flag of
379 -- Old is set and Old has no yet been Frozen (i.e. Is_Frozen is false).
382 -- Determine whether pragma Prag contains a reference to the entity of an
383 -- abstract state with a visible refinement. Prag must denote one of the
384 -- following pragmas:
385 -- Depends
386 -- Global
389 -- Utility to create a parameter profile for a new subprogram spec, when
390 -- the subprogram has a body that acts as spec. This is done for some cases
391 -- of inlining, and for private protected ops. Also used to create bodies
392 -- for stubbed subprograms.
394 function Copy_Component_List
397 -- Copy components from record type R_Typ that come from source. Used to
398 -- create a new compatible record type. Loc is the source location assigned
399 -- to the created nodes.
402 -- If a type is a generic actual type, return the corresponding formal in
403 -- the generic parent unit. There is no direct link in the tree for this
404 -- attribute, except in the case of formal private and derived types.
405 -- Possible optimization???
409 -- Find the currently visible definition for a given identifier, that is to
410 -- say the first entry in the visibility chain for the Chars of N.
413 -- Find whether there is a previous definition for identifier N in the
414 -- current scope. Because declarations for a scope are not necessarily
415 -- contiguous (e.g. for packages) the first entry on the visibility chain
416 -- for N is not necessarily in the current scope.
419 -- Get entity representing current scope
422 -- Returns current enclosing subprogram. If Current_Scope is a subprogram,
423 -- then that is what is returned, otherwise the Enclosing_Subprogram of the
424 -- Current_Scope is returned. The returned value is Empty if this is called
425 -- from a library package which is not within any subprogram.
428 -- Same as Type_Access_Level, except that if the type is the type of an Ada
429 -- 2012 stand-alone object of an anonymous access type, then return the
430 -- static accesssibility level of the object. In that case, the dynamic
431 -- accessibility level of the object may take on values in a range. The low
432 -- bound of of that range is returned by Type_Access_Level; this function
433 -- yields the high bound of that range. Also differs from Type_Access_Level
434 -- in the case of a descendant of a generic formal type (returns Int'Last
435 -- instead of 0).
438 -- Given a declaration N, returns the associated defining entity. If the
439 -- declaration has a specification, the entity is obtained from the
440 -- specification. If the declaration has a defining unit name, then the
441 -- defining entity is obtained from the defining unit name ignoring any
442 -- child unit prefixes.
444 function Denotes_Discriminant
447 -- Returns True if node N is an Entity_Name node for a discriminant. If the
448 -- flag Check_Concurrent is true, function also returns true when N denotes
449 -- the discriminal of the discriminant of a concurrent type. This is needed
450 -- to disable some optimizations on private components of protected types,
451 -- and constraint checks on entry families constrained by discriminants.
454 -- Detect suspicious overlapping between actuals in a call, when both are
455 -- writable (RM 2012 6.4.1(6.4/3))
458 -- Functions to detect suspicious overlapping between actuals in a call,
459 -- when one of them is writable. The predicates are those proposed in
460 -- AI05-0144, to detect dangerous order dependence in complex calls.
461 -- I would add a parameter Warn which enables more extensive testing of
462 -- cases as we find appropriate when we are only warning ??? Or perhaps
463 -- return an indication of (Error, Warn, OK) ???
466 -- Returns True if node N denotes a single variable without parentheses
469 -- Returns True if N denotes a discriminant or if N is a range, a subtype
470 -- indication or a scalar subtype where one of the bounds is a
471 -- discriminant.
473 function Designate_Same_Unit
476 -- Return true if Name1 and Name2 designate the same unit name; each of
477 -- these names is supposed to be a selected component name, an expanded
478 -- name, a defining program unit name or an identifier.
481 -- Expr should be an expression of an access type. Builds an integer
482 -- literal except in cases involving anonymous access types where
483 -- accessibility levels are tracked at runtime (access parameters and Ada
484 -- 2012 stand-alone objects).
487 -- Same as Einfo.Extra_Accessibility except thtat object renames
488 -- are looked through.
491 -- Given the entity of an abstract state or a variable, determine whether
492 -- Id is subject to external property Effective_Reads and if it is, the
493 -- related expression evaluates to True.
496 -- Given the entity of an abstract state or a variable, determine whether
497 -- Id is subject to external property Effective_Writes and if it is, the
498 -- related expression evaluates to True.
501 -- Returns the enclosing N_Compilation_Unit Node that is the root of a
502 -- subtree containing N.
505 -- Returns the closest ancestor of Typ that is a CPP type.
507 function Enclosing_Generic_Body
509 -- Returns the Node_Id associated with the innermost enclosing generic
510 -- body, if any. If none, then returns Empty.
512 function Enclosing_Generic_Unit
514 -- Returns the Node_Id associated with the innermost enclosing generic
515 -- unit, if any. If none, then returns Empty.
517 function Enclosing_Lib_Unit_Entity
519 -- Returns the entity of enclosing library unit node which is the
520 -- root of the current scope (which must not be Standard_Standard, and the
521 -- caller is responsible for ensuring this condition) or other specified
522 -- entity.
525 -- Utility function to return the Ada entity of the package enclosing
526 -- the entity E, if any. Returns Empty if no enclosing package.
529 -- Utility function to return the Ada entity of the subprogram enclosing
530 -- the entity E, if any. Returns Empty if no enclosing subprogram.
533 -- Make sure a freeze node is allocated for entity E. If necessary, build
534 -- and initialize a new freeze node and set Has_Delayed_Freeze True for E.
537 -- Insert new name in symbol table of current scope with check for
538 -- duplications (error message is issued if a conflict is found).
539 -- Note: Enter_Name is not used for overloadable entities, instead these
540 -- are entered using Sem_Ch6.Enter_Overloadable_Entity.
543 -- Return the entity of N or Empty. If N is a renaming, return the entity
544 -- of the root renamed object.
547 -- This procedure is called after issuing a message complaining about an
548 -- inappropriate use of limited type T. If useful, it adds additional
549 -- continuation lines to the message explaining why type T is limited.
550 -- Messages are placed at node N.
552 procedure Find_Actual
556 -- Determines if the node N is an actual parameter of a function of a
557 -- procedure call. If so, then Formal points to the entity for the formal
558 -- (Ekind is E_In_Parameter, E_Out_Parameter, or E_In_Out_Parameter) and
559 -- Call is set to the node for the corresponding call. If the node N is not
560 -- an actual parameter then Formal and Call are set to Empty.
562 function Find_Body_Discriminal
564 -- Given a discriminant of the record type that implements a task or
565 -- protected type, return the discriminal of the corresponding discriminant
566 -- of the actual concurrent type.
568 function Find_Corresponding_Discriminant
571 -- Because discriminants may have different names in a generic unit and in
572 -- an instance, they are resolved positionally when possible. A reference
573 -- to a discriminant carries the discriminant that it denotes when it is
574 -- analyzed. Subsequent uses of this id on a different type denotes the
575 -- discriminant at the same position in this new type.
578 -- Given an arbitrary entity, try to find the nearest enclosing iterator
579 -- loop. If such a loop is found, return the entity of its identifier (the
580 -- E_Loop scope), otherwise return Empty.
583 -- Find the nested loop statement in a conditional block. Loops subject to
584 -- attribute 'Loop_Entry are transformed into blocks. Parts of the original
585 -- loop are nested within the block.
587 procedure Find_Overlaid_Entity
591 -- The node N should be an address representation clause. Determines if
592 -- the target expression is the address of an entity with an optional
593 -- offset. If so, set Ent to the entity and, if there is an offset, set
594 -- Off to True, otherwise to False. If N is not an address representation
595 -- clause, or if it is not possible to determine that the address is of
596 -- this form, then set Ent to Empty.
599 -- Return the type of formal parameter Param as determined by its
600 -- specification.
602 -- The following type describes the placement of an arbitrary entity with
603 -- respect to SPARK visible / hidden state space.
607 -- An entity is not in the visible, private or body state space when
608 -- the immediate enclosing construct is not a package.
610 Visible_State_Space,
611 -- An entity is in the visible state space when it appears immediately
612 -- within the visible declarations of a package or when it appears in
613 -- the visible state space of a nested package which in turn is declared
614 -- in the visible declarations of an enclosing package:
616 -- package Pack is
617 -- Visible_Variable : ...
618 -- package Nested
619 -- with Abstract_State => Visible_State
620 -- is
621 -- Visible_Nested_Variable : ...
622 -- end Nested;
623 -- end Pack;
625 -- Entities associated with a package instantiation inherit the state
626 -- space from the instance placement:
628 -- generic
629 -- package Gen is
630 -- Generic_Variable : ...
631 -- end Gen;
633 -- with Gen;
634 -- package Pack is
635 -- package Inst is new Gen;
636 -- -- Generic_Variable is in the visible state space of Pack
637 -- end Pack;
639 Private_State_Space,
640 -- An entity is in the private state space when it appears immediately
641 -- within the private declarations of a package or when it appears in
642 -- the visible state space of a nested package which in turn is declared
643 -- in the private declarations of an enclosing package:
645 -- package Pack is
646 -- private
647 -- Private_Variable : ...
648 -- package Nested
649 -- with Abstract_State => Private_State
650 -- is
651 -- Private_Nested_Variable : ...
652 -- end Nested;
653 -- end Pack;
655 -- The same placement principle applies to package instantiations
657 Body_State_Space);
658 -- An entity is in the body state space when it appears immediately
659 -- within the declarations of a package body or when it appears in the
660 -- visible state space of a nested package which in turn is declared in
661 -- the declarations of an enclosing package body:
663 -- package body Pack is
664 -- Body_Variable : ...
665 -- package Nested
666 -- with Abstract_State => Body_State
667 -- is
668 -- Body_Nested_Variable : ...
669 -- end Nested;
670 -- end Pack;
672 -- The same placement principle applies to package instantiations
674 procedure Find_Placement_In_State_Space
678 -- Determine the state space placement of an item. Item_Id denotes the
679 -- entity of an abstract state, variable or package instantiation.
680 -- Placement captures the precise placement of the item in the enclosing
681 -- state space. If the state space is that of a package, Pack_Id denotes
682 -- its entity, otherwise Pack_Id is Empty.
685 -- N is a case statement whose expression is a compile-time value.
686 -- Determine the alternative chosen, so that the code of non-selected
687 -- alternatives, and the warnings that may apply to them, are removed.
690 -- Node is an N_Function_Call or N_Procedure_Call_Statement node. The
691 -- result returned is the first actual parameter in declaration order
692 -- (not the order of parameters as they appeared in the source, which
693 -- can be quite different as a result of the use of named parameters).
694 -- Empty is returned for a call with no parameters. The procedure for
695 -- iterating through the actuals in declaration order is to use this
696 -- function to find the first actual, and then use Next_Actual to obtain
697 -- the next actual in declaration order. Note that the value returned
698 -- is always the expression (not the N_Parameter_Association nodes,
699 -- even if named association is used).
701 procedure Gather_Components
707 -- The purpose of this procedure is to gather the valid components in a
708 -- record type according to the values of its discriminants, in order to
709 -- validate the components of a record aggregate.
710 --
711 -- Typ is the type of the aggregate when its constrained discriminants
712 -- need to be collected, otherwise it is Empty.
713 --
714 -- Comp_List is an N_Component_List node.
715 --
716 -- Governed_By is a list of N_Component_Association nodes, where each
717 -- choice list contains the name of a discriminant and the expression
718 -- field gives its value. The values of the discriminants governing
719 -- the (possibly nested) variant parts in Comp_List are found in this
720 -- Component_Association List.
721 --
722 -- Into is the list where the valid components are appended. Note that
723 -- Into need not be an Empty list. If it's not, components are attached
724 -- to its tail.
725 --
726 -- Report_Errors is set to True if the values of the discriminants are
727 -- non-static.
728 --
729 -- This procedure is also used when building a record subtype. If the
730 -- discriminant constraint of the subtype is static, the components of the
731 -- subtype are only those of the variants selected by the values of the
732 -- discriminants. Otherwise all components of the parent must be included
733 -- in the subtype for semantic analysis.
736 -- Given a node for an expression, obtain the actual subtype of the
737 -- expression. In the case of a parameter where the formal is an
738 -- unconstrained array or discriminated type, this will be the previously
739 -- constructed subtype of the actual. Note that this is not quite the
740 -- "Actual Subtype" of the RM, since it is always a constrained type, i.e.
741 -- it is the subtype of the value of the actual. The actual subtype is also
742 -- returned in other cases where it has already been constructed for an
743 -- object. Otherwise the expression type is returned unchanged, except for
744 -- the case of an unconstrained array type, where an actual subtype is
745 -- created, using Insert_Actions if necessary to insert any associated
746 -- actions.
749 -- This is like Get_Actual_Subtype, except that it never constructs an
750 -- actual subtype. If an actual subtype is already available, i.e. the
751 -- Actual_Subtype field of the corresponding entity is set, then it is
752 -- returned. Otherwise the Etype of the node is returned.
755 -- Return the body node for a stub (subprogram or package)
757 function Get_Cursor_Type
760 -- Find Cursor type in scope of formal container Typ, by locating primitive
761 -- operation First. For use in resolving the other primitive operations
762 -- of an Iterable type and expanding loops and quantified expressions
763 -- over formal containers.
766 -- This is used to construct the string literal node representing a
767 -- default external name, i.e. one that is constructed from the name of an
768 -- entity, or (in the case of extended DEC import/export pragmas, an
769 -- identifier provided as the external name. Letters in the name are
770 -- according to the setting of Opt.External_Name_Default_Casing.
773 -- If expression N references a part of an object, return this object.
774 -- Otherwise return Empty. Expression N should have been resolved already.
777 -- Return the Ensures component of Test_Case pragma N, or Empty otherwise
778 -- Bad name now that this no longer applies to Contract_Case ???
781 -- Returns the true generic entity in an instantiation. If the name in the
782 -- instantiation is a renaming, the function returns the renamed generic.
785 -- Implements the notion introduced ever-so briefly in RM 7.3.1 (5.2/3):
786 -- in a child unit a derived type is within the derivation class of an
787 -- ancestor declared in a parent unit, even if there is an intermediate
788 -- derivation that does not see the full view of that ancestor.
791 -- This procedure assigns to L and H respectively the values of the low and
792 -- high bounds of node N, which must be a range, subtype indication, or the
793 -- name of a scalar subtype. The result in L, H may be set to Error if
794 -- there was an earlier error in the range.
796 function Get_Enum_Lit_From_Pos
800 -- This function returns an identifier denoting the E_Enumeration_Literal
801 -- entity for the specified value from the enumeration type or subtype T.
802 -- The second argument is the Pos value, which is assumed to be in range.
803 -- The third argument supplies a source location for constructed nodes
804 -- returned by this function.
806 function Get_Iterable_Type_Primitive
809 -- Retrieve one of the primitives First, Next, Has_Element, Element from
810 -- the value of the Iterable aspect of a formal type.
813 -- Retrieve the fully expanded name of the library unit declared by
814 -- Decl_Node into the name buffer.
818 -- An entity value is associated with each name in the name table. The
819 -- Get_Name_Entity_Id function fetches the Entity_Id of this entity, which
820 -- is the innermost visible entity with the given name. See the body of
821 -- Sem_Ch8 for further details on handling of entity visibility.
824 -- Return the Name component of Test_Case pragma N
825 -- Bad name now that this no longer applies to Contract_Case ???
829 -- Obtains the Pragma_Id from the Chars field of Pragma_Identifier (N)
832 -- Recursive routine to analyze reason argument for pragma Warnings. The
833 -- value of the reason argument is appended to the current string using
834 -- Store_String_Chars. The reason argument is expected to be a string
835 -- literal or concatenation of string literals. An error is given for
836 -- any other form.
839 -- Given a node, return the renamed object if the node represents a renamed
840 -- object, otherwise return the node unchanged. The node may represent an
841 -- arbitrary expression.
844 -- Given an entity for an exception, package, subprogram or generic unit,
845 -- returns the ultimately renamed entity if this is a renaming. If this is
846 -- not a renamed entity, returns its argument. It is an error to call this
847 -- with any other kind of entity.
850 -- Return the Requires component of Test_Case pragma N, or Empty otherwise
851 -- Bad name now that this no longer applies to Contract_Case ???
854 -- Nod is either a procedure call statement, or a function call, or an
855 -- accept statement node. This procedure finds the Entity_Id of the related
856 -- subprogram or entry and returns it, or if no subprogram can be found,
857 -- returns Empty.
860 -- Given the entity for a subprogram (E_Function or E_Procedure), return
861 -- the corresponding N_Subprogram_Body node. If the corresponding body
862 -- is missing (as for an imported subprogram), return Empty.
866 -- Given an entity for a task type or subtype, retrieves the
867 -- Task_Body_Procedure field from the corresponding task type declaration.
870 -- Returns true if type or subtype T is an access type, or has a component
871 -- (at any recursive level) that is an access type. This is a conservative
872 -- predicate, if it is not known whether or not T contains access values
873 -- (happens for generic formals in some cases), then False is returned.
874 -- Note that tagged types return False. Even though the tag is implemented
875 -- as an access type internally, this function tests only for access types
876 -- known to the programmer. See also Has_Tagged_Component.
879 -- Result of Has_Compatible_Alignment test, description found below. Note
880 -- that the values are arranged in increasing order of problematicness.
882 function Has_Compatible_Alignment
885 -- Obj is an object entity, and expr is a node for an object reference. If
886 -- the alignment of the object referenced by Expr is known to be compatible
887 -- with the alignment of Obj (i.e. is larger or the same), then the result
888 -- is Known_Compatible. If the alignment of the object referenced by Expr
889 -- is known to be less than the alignment of Obj, then Known_Incompatible
890 -- is returned. If neither condition can be reliably established at compile
891 -- time, then Unknown is returned. This is used to determine if alignment
892 -- checks are required for address clauses, and also whether copies must
893 -- be made when objects are passed by reference.
894 --
895 -- Note: Known_Incompatible does not mean that at run time the alignment
896 -- of Expr is known to be wrong for Obj, just that it can be determined
897 -- that alignments have been explicitly or implicitly specified which are
898 -- incompatible (whereas Unknown means that even this is not known). The
899 -- appropriate reaction of a caller to Known_Incompatible is to treat it as
900 -- Unknown, but issue a warning that there may be an alignment error.
903 -- Determines if the node can have declarations
906 -- Determines if the floating-point type E supports denormal numbers.
907 -- Returns False if E is not a floating-point type.
909 function Has_Discriminant_Dependent_Constraint
911 -- Returns True if and only if Comp has a constrained subtype that depends
912 -- on a discriminant.
915 -- Determines if the range of the floating-point type E includes
916 -- infinities. Returns False if E is not a floating-point type.
918 function Has_Interfaces
921 -- Where T is a concurrent type or a record type, returns true if T covers
922 -- any abstract interface types. In case of private types the argument
923 -- Use_Full_View controls if the check is done using its full view (if
924 -- available).
927 -- This is a simple minded function for determining whether an expression
928 -- has no obvious side effects. It is used only for determining whether
929 -- warnings are needed in certain situations, and is not guaranteed to
930 -- be accurate in either direction. Exceptions may mean an expression
931 -- does in fact have side effects, but this may be ignored and True is
932 -- returned, or a complex expression may in fact be side effect free
933 -- but we don't recognize it here and return False. The Side_Effect_Free
934 -- routine in Remove_Side_Effects is much more extensive and perhaps could
935 -- be shared, so that this routine would be more accurate.
938 -- Determine whether node N has a null exclusion
941 -- Predicate to determine whether a controlled type has a user-defined
942 -- Initialize primitive (and, in Ada 2012, whether that primitive is
943 -- non-null), which causes the type to not have preelaborable
944 -- initialization.
947 -- Return True iff type E has preelaborable initialization as defined in
948 -- Ada 2005 (see AI-161 for details of the definition of this attribute).
951 -- Check if a type has a (sub)component of a private type that has not
952 -- yet received a full declaration.
955 -- Determines if the floating-point type E supports signed zeros.
956 -- Returns False if E is not a floating-point type.
959 -- Return whether an array type has static bounds
962 -- Tests if type T is derived from Ada.Streams.Root_Stream_Type, or in the
963 -- case of a composite type, has a component for which this predicate is
964 -- True, and if so returns True. Otherwise a result of False means that
965 -- there is no Stream type in sight. For a private type, the test is
966 -- applied to the underlying type (or returns False if there is no
967 -- underlying type).
970 -- Returns true if the last character of E is Suffix. Used in Assertions.
973 -- Returns the name of E adding Suffix
976 -- Returns the name of E without Suffix
979 -- Returns True if Typ is a composite type (array or record) which is
980 -- either itself a tagged type, or has a component (recursively) which is
981 -- a tagged type. Returns False for non-composite type, or if no tagged
982 -- component is present. This function is used to check if "=" has to be
983 -- expanded into a bunch component comparisons.
986 -- Given an arbitrary type, determine whether it contains at least one
987 -- volatile component.
990 -- Subp is a subprogram marked with pragma Implemented. Return the specific
991 -- implementation requirement which the pragma imposes. The return value is
992 -- either Name_By_Any, Name_By_Entry or Name_By_Protected_Procedure.
994 function Implements_Interface
998 -- Returns true if the Typ_Ent implements interface Iface_Ent
1001 -- Determine whether an arbitrary node appears in a pragma that acts as an
1002 -- assertion expression. See Sem_Prag for the list of qualifying pragmas.
1005 -- Returns True if the current scope is within a generic instance
1008 -- Returns True if current scope is within the body of an instance, where
1009 -- several semantic checks (e.g. accessibility checks) are relaxed.
1012 -- Returns True if current scope is with the private part or the body of
1013 -- an instance. Other semantic checks are suppressed in this context.
1016 -- Returns True if current scope is within the visible part of a package
1017 -- instance, where several additional semantic checks apply.
1020 -- Returns True if current scope is within a package body
1023 -- Returns True if node N belongs to a parameter specification
1026 -- Returns true if the expression N occurs within a pragma with name Nam
1029 -- Returns True if N denotes a component or subcomponent in a record or
1030 -- array that has Reverse_Storage_Order.
1033 -- Determines if the current scope is within a subprogram compilation unit
1034 -- (inside a subprogram declaration, subprogram body, or generic subprogram
1035 -- declaration) or within a task or protected body. The test is for
1036 -- appearing anywhere within such a construct (that is it does not need
1037 -- to be directly within).
1040 -- Determine whether a declaration occurs within the visible part of a
1041 -- package specification. The package must be on the scope stack, and the
1042 -- corresponding private part must not.
1045 -- Given the entity of a type, retrieve the incomplete or private view of
1046 -- the same type. Note that Typ may not have a partial view to begin with,
1047 -- in that case the function returns Empty.
1050 -- In a context that requires a composite or subprogram type and where a
1051 -- prefix is an access type, rewrite the access type node N (which is the
1052 -- prefix, e.g. of an indexed component) as an explicit dereference.
1055 -- Examine all deferred constants in the declaration list Decls and check
1056 -- whether they have been completed by a full constant declaration or an
1057 -- Import pragma. Emit the error message if that is not the case.
1060 -- Determines if N is an actual parameter of out mode in a subprogram call
1063 -- Determines if N is an actual parameter in a subprogram call
1066 -- Determines if N is an actual parameter of a formal of tagged type in a
1067 -- subprogram call.
1070 -- Determine if Obj is an aliased view, i.e. the name of an object to which
1071 -- 'Access or 'Unchecked_Access can apply. Note that this routine uses the
1072 -- rules of the language, it does not take into account the restriction
1073 -- No_Implicit_Aliasing, so it can return True if the restriction is active
1074 -- and Obj violates the restriction. The caller is responsible for calling
1075 -- Restrict.Check_No_Implicit_Aliasing if True is returned, but there is a
1076 -- requirement for obeying the restriction in the call context.
1078 function Is_Ancestor_Package
1081 -- Determine whether package E1 is an ancestor of E2
1084 -- Determines if the given node denotes an atomic object in the sense of
1085 -- the legality checks described in RM C.6(12).
1088 -- Determine whether node N denotes attribute 'Result
1091 -- Determine whether node N denotes a body or a package declaration
1094 -- True if T is a bounded string type. Used to make sure "=" composes
1095 -- properly for bounded string types.
1098 -- Exp is the expression for an array bound. Determines whether the
1099 -- bound is a compile-time known value, or a constant entity, or an
1100 -- enumeration literal, or an expression composed of constant-bound
1101 -- subexpressions which are evaluated by means of standard operators.
1104 -- This routine recognizes expressions that denote an element of one of
1105 -- the predefined containers, when the source only contains an indexing
1106 -- operation and an implicit dereference is inserted by the compiler.
1107 -- In the absence of this optimization, the indexing creates a temporary
1108 -- controlled cursor that sets the tampering bit of the container, and
1109 -- restricts the use of the convenient notation C (X) to contexts that
1110 -- do not check the tampering bit (e.g. C.Include (X, C (Y)). Exp is an
1111 -- explicit dereference. The transformation applies when it has the form
1112 -- F (X).Discr.all.
1114 function Is_Controlling_Limited_Procedure
1116 -- Ada 2005 (AI-345): Determine whether Proc_Nam is a primitive procedure
1117 -- of a limited interface with a controlling first parameter.
1120 -- Returns True if N is a call to a CPP constructor
1122 function Is_Child_Or_Sibling
1125 -- Determine the following relations between two arbitrary packages:
1126 -- 1) One package is the parent of a child package
1127 -- 2) Both packages are siblings and share a common parent
1130 -- First determine whether type T is an interface and then check whether
1131 -- it is of protected, synchronized or task kind.
1134 -- Returns true if type T represents a delegate. A Delegate is the CIL
1135 -- object used to represent access-to-subprogram types. This is only
1136 -- relevant to CIL, will always return false for other targets.
1138 function Is_Dependent_Component_Of_Mutable_Object
1140 -- Returns True if Object is the name of a subcomponent that depends on
1141 -- discriminants of a variable whose nominal subtype is unconstrained and
1142 -- not indefinite, and the variable is not aliased. Otherwise returns
1143 -- False. The nodes passed to this function are assumed to denote objects.
1146 -- N is a subexpression node of an access type. This function returns true
1147 -- if N appears as the prefix of a node that does a dereference of the
1148 -- access value (selected/indexed component, explicit dereference or a
1149 -- slice), and false otherwise.
1152 -- Returns True if type T1 is a descendent of type T2, and false otherwise.
1153 -- This is the RM definition, a type is a descendent of another type if it
1154 -- is the same type or is derived from a descendent of the other type.
1157 -- Predicate to determine whether a scope entity comes from a rewritten
1158 -- expression function call, and should be inlined unconditionally. Also
1159 -- used to determine that such a call does not constitute a freeze point.
1163 -- The argument is a Uint value which is the Boolean'Pos value of a Boolean
1164 -- operand (i.e. is either 0 for False, or 1 for True). This function tests
1165 -- if it is False (i.e. zero).
1168 -- Returns True iff the number U is a model number of the fixed-point type
1169 -- T, i.e. if it is an exact multiple of Small.
1172 -- Typ is a type entity. This function returns true if this type is fully
1173 -- initialized, meaning that an object of the type is fully initialized.
1174 -- Note that initialization resulting from use of pragma Normalized_Scalars
1175 -- does not count. Note that this is only used for the purpose of issuing
1176 -- warnings for objects that are potentially referenced uninitialized. This
1177 -- means that the result returned is not crucial, but should err on the
1178 -- side of thinking things are fully initialized if it does not know.
1181 -- E is a subprogram. Return True is E is an implicit operation inherited
1182 -- by a derived type declaration.
1184 function Is_Inherited_Operation_For_Type
1187 -- E is a subprogram. Return True is E is an implicit operation inherited
1188 -- by the derived type declaration for type Typ.
1191 -- AI05-0139-2: Check whether Typ is one of the predefined interfaces in
1192 -- Ada.Iterator_Interfaces, or it is derived from one.
1195 -- Returns True if the given name contains any of the following substrings
1196 -- discard
1197 -- dummy
1198 -- ignore
1199 -- junk
1200 -- unused
1201 -- Used to suppress warnings on names matching these patterns. The contents
1202 -- of Name_Buffer and Name_Len are desteoyed by this call.
1206 -- Returns Yes if N is definitely used as Name in an assignment statement.
1207 -- Returns No if N is definitely NOT used as a Name in an assignment
1208 -- statement. Returns Unknown if we can't tell at this stage (happens in
1209 -- the case where we don't know the type of N yet, and we have something
1210 -- like N.A := 3, where this counts as N being used on the left side of
1211 -- an assignment only if N is not an access type. If it is an access type
1212 -- then it is N.all.A that is assigned, not N.
1215 -- A library-level declaration is one that is accessible from Standard,
1216 -- i.e. a library unit or an entity declared in a library package.
1219 -- Determine whether a given type is a limited class-wide type, in which
1220 -- case it needs a Master_Id, because extensions of its designated type
1221 -- may include task components. A class-wide type that comes from a
1222 -- limited view must be treated in the same way.
1225 -- Determines whether Expr is a reference to a variable or IN OUT mode
1226 -- parameter of the current enclosing subprogram.
1227 -- Why are OUT parameters not considered here ???
1230 -- Determines if the tree referenced by N represents an object. Both
1231 -- variable and constant objects return True (compare Is_Variable).
1234 -- Used to test if AV is an acceptable formal for an OUT or IN OUT formal.
1235 -- Note that the Is_Variable function is not quite the right test because
1236 -- this is a case in which conversions whose expression is a variable (in
1237 -- the Is_Variable sense) with a non-tagged type target are considered view
1238 -- conversions and hence variables.
1240 function Is_Partially_Initialized_Type
1243 -- Typ is a type entity. This function returns true if this type is partly
1244 -- initialized, meaning that an object of the type is at least partly
1245 -- initialized (in particular in the record case, that at least one
1246 -- component has an initialization expression). Note that initialization
1247 -- resulting from the use of pragma Normalized_Scalars does not count.
1248 -- Include_Implicit controls whether implicit initialization of access
1249 -- values to null, and of discriminant values, is counted as making the
1250 -- type be partially initialized. For the default setting of True, these
1251 -- implicit cases do count, and discriminated types or types containing
1252 -- access values not explicitly initialized will return True. Otherwise
1253 -- if Include_Implicit is False, these cases do not count as making the
1254 -- type be partially initialized.
1257 -- Predicate to implement definition given in RM 6.1.1 (20/3)
1260 -- Determines if type T is a potentially persistent type. A potentially
1261 -- persistent type is defined (recursively) as a scalar type, a non-tagged
1262 -- record whose components are all of a potentially persistent type, or an
1263 -- array with all static constraints whose component type is potentially
1264 -- persistent. A private type is potentially persistent if the full type
1265 -- is potentially persistent.
1268 -- Return True if node N denotes a protected type name which represents
1269 -- the current instance of a protected object according to RM 9.4(21/2).
1272 -- Return True if a compilation unit is the specification or the
1273 -- body of a remote call interface package.
1276 -- Return True if E is a remote access-to-class-wide type
1279 -- Return True if E is a remote access to subprogram type
1282 -- Return True if N denotes a potentially remote call
1285 -- Return True if Proc_Nam is a procedure renaming of an entry
1288 -- AI05-0139-2: Check whether Typ is derived from the predefined interface
1289 -- Ada.Iterator_Interfaces.Reversible_Iterator.
1292 -- Given an N_Identifier node N, determines if it is a Selector_Name.
1293 -- As described in Sinfo, Selector_Names are special because they
1294 -- represent use of the N_Identifier node for a true identifier, when
1295 -- normally such nodes represent a direct name.
1298 -- Determines if the tree referenced by N represents an initialization
1299 -- expression in SPARK, suitable for initializing an object in an object
1300 -- declaration.
1303 -- Determines if the tree referenced by N represents an object in SPARK
1306 -- Determine whether an arbitrary node denotes a volatile object reference
1307 -- according to the semantics of SPARK. To qualify as volatile, an object
1308 -- must be subject to aspect/pragma Volatile or Atomic or have a [sub]type
1309 -- subject to the same attributes. Note that volatile components do not
1310 -- render an object volatile.
1314 -- Check if the node N is a statement node. Note that this includes
1315 -- the case of procedure call statements (unlike the direct use of
1316 -- the N_Statement_Other_Than_Procedure_Call subtype from Sinfo).
1317 -- Note that a label is *not* a statement, and will return False.
1319 function Is_Subprogram_Stub_Without_Prior_Declaration
1321 -- Return True if N is a subprogram stub with no prior subprogram
1322 -- declaration.
1325 -- Returns True if E is a synchronized tagged type (AARM 3.9.4 (6/2))
1328 -- Returns True if the node N is a statement which is known to cause an
1329 -- unconditional transfer of control at runtime, i.e. the following
1330 -- statement definitely will not be executed.
1334 -- The argument is a Uint value which is the Boolean'Pos value of a Boolean
1335 -- operand (i.e. is either 0 for False, or 1 for True). This function tests
1336 -- if it is True (i.e. non-zero).
1339 -- Determine whether an arbitrary entity denotes an instance of function
1340 -- Ada.Unchecked_Conversion.
1344 -- True if T is Universal_Integer or Universal_Real
1347 -- Returns true if type T represents a value type. This is only relevant to
1348 -- CIL, will always return false for other targets. A value type is a CIL
1349 -- object that is accessed directly, as opposed to the other CIL objects
1350 -- that are accessed through managed pointers.
1353 -- Returns true if E has variable size components
1356 -- Returns true if E has variable size components
1359 -- Determine whether an operator is one of the intrinsics defined
1360 -- in the DEC system extension.
1362 function Is_Variable
1365 -- Determines if the tree referenced by N represents a variable, i.e. can
1366 -- appear on the left side of an assignment. There is one situation (formal
1367 -- parameters) in which non-tagged type conversions are also considered
1368 -- variables, but Is_Variable returns False for such cases, since it has
1369 -- no knowledge of the context. Note that this is the point at which
1370 -- Assignment_OK is checked, and True is returned for any tree thus marked.
1371 -- Use_Original_Node is used to perform the test on Original_Node (N). By
1372 -- default is True since this routine is commonly invoked as part of the
1373 -- semantic analysis and it must not be disturbed by the rewriten nodes.
1376 -- Check whether T is derived from a visibly controlled type. This is true
1377 -- if the root type is declared in Ada.Finalization. If T is derived
1378 -- instead from a private type whose full view is controlled, an explicit
1379 -- Initialize/Adjust/Finalize subprogram does not override the inherited
1380 -- one.
1383 -- Determines if the given node denotes an volatile object in the sense of
1384 -- the legality checks described in RM C.6(12). Note that the test here is
1385 -- for something actually declared as volatile, not for an object that gets
1386 -- treated as volatile (see Einfo.Treat_As_Volatile).
1389 -- Applies to Itypes. True if the Itype is attached to a declaration for
1390 -- the type through its Parent field, which may or not be present in the
1391 -- tree.
1394 -- This procedure is called to clear all constant indications from all
1395 -- entities in the current scope and in any parent scopes if the current
1396 -- scope is a block or a package (and that recursion continues to the top
1397 -- scope that is not a block or a package). This is used when the
1398 -- sequential flow-of-control assumption is violated (occurrence of a
1399 -- label, head of a loop, or start of an exception handler). The effect of
1400 -- the call is to clear the Current_Value field (but we do not need to
1401 -- clear the Is_True_Constant flag, since that only gets reset if there
1402 -- really is an assignment somewhere in the entity scope). This procedure
1403 -- also calls Kill_All_Checks, since this is a special case of needing to
1404 -- forget saved values. This procedure also clears the Is_Known_Null and
1405 -- Is_Known_Non_Null and Is_Known_Valid flags in variables, constants or
1406 -- parameters since these are also not known to be trustable any more.
1407 --
1408 -- The Last_Assignment_Only flag is set True to clear only Last_Assignment
1409 -- fields and leave other fields unchanged. This is used when we encounter
1410 -- an unconditional flow of control change (return, goto, raise). In such
1411 -- cases we don't need to clear the current values, since it may be that
1412 -- the flow of control change occurs in a conditional context, and if it
1413 -- is not taken, then it is just fine to keep the current values. But the
1414 -- Last_Assignment field is different, if we have a sequence assign-to-v,
1415 -- conditional-return, assign-to-v, we do not want to complain that the
1416 -- second assignment clobbers the first.
1418 procedure Kill_Current_Values
1421 -- This performs the same processing as described above for the form with
1422 -- no argument, but for the specific entity given. The call has no effect
1423 -- if the entity Ent is not for an object. Last_Assignment_Only has the
1424 -- same meaning as for the call with no Ent.
1427 -- Called when an address clause or pragma Import is applied to an entity.
1428 -- If the entity is a variable or a constant, and size check code is
1429 -- present, this size check code is killed, since the object will not be
1430 -- allocated by the program.
1433 -- The node N is an entity reference. This function determines whether the
1434 -- reference is for sure an assignment of the entity, returning True if
1435 -- so. This differs from May_Be_Lvalue in that it defaults in the other
1436 -- direction. Cases which may possibly be assignments but are not known to
1437 -- be may return True from May_Be_Lvalue, but False from this function.
1440 -- HSS is a handled statement sequence. This function returns the last
1441 -- statement in Statements (HSS) that has Comes_From_Source set. If no
1442 -- such statement exists, Empty is returned.
1444 function Matching_Static_Array_Bounds
1447 -- L_Typ and R_Typ are two array types. Returns True when they have the
1448 -- same number of dimensions, and the same static bounds for each index
1449 -- position.
1452 -- Given a node which designates the context of analysis and an origin in
1453 -- the tree, traverse from Root_Nod and mark all allocators as either
1454 -- dynamic or static depending on Context_Nod. Any erroneous marking is
1455 -- cleaned up during resolution.
1458 -- Determines if N could be an lvalue (e.g. an assignment left hand side).
1459 -- An lvalue is defined as any expression which appears in a context where
1460 -- a name is required by the syntax, and the identity, rather than merely
1461 -- the value of the node is needed (for example, the prefix of an Access
1462 -- attribute is in this category). Note that, as implied by the name, this
1463 -- test is conservative. If it cannot be sure that N is NOT an lvalue, then
1464 -- it returns True. It tries hard to get the answer right, but it is hard
1465 -- to guarantee this in all cases. Note that it is more possible to give
1466 -- correct answer if the tree is fully analyzed.
1469 -- Return true if Subp must be inlined by the frontend
1472 -- Returns True if a function has defaults for all but its first
1473 -- formal. Used in Ada 2005 mode to solve the syntactic ambiguity that
1474 -- results from an indexing of a function call written in prefix form.
1477 -- Copy recursively an analyzed list of nodes. Uses New_Copy_Tree defined
1478 -- below. As for New_Copy_Tree, it is illegal to attempt to copy extended
1479 -- nodes (entities) either directly or indirectly using this function.
1481 function New_Copy_Tree
1486 -- Given a node that is the root of a subtree, Copy_Tree copies the entire
1487 -- syntactic subtree, including recursively any descendents whose parent
1488 -- field references a copied node (descendents not linked to a copied node
1489 -- by the parent field are not copied, instead the copied tree references
1490 -- the same descendent as the original in this case, which is appropriate
1491 -- for non-syntactic fields such as Etype). The parent pointers in the
1492 -- copy are properly set. Copy_Tree (Empty/Error) returns Empty/Error.
1493 -- The one exception to the rule of not copying semantic fields is that
1494 -- any implicit types attached to the subtree are duplicated, so that
1495 -- the copy contains a distinct set of implicit type entities. Thus this
1496 -- function is used when it is necessary to duplicate an analyzed tree,
1497 -- declared in the same or some other compilation unit. This function is
1498 -- declared here rather than in atree because it uses semantic information
1499 -- in particular concerning the structure of itypes and the generation of
1500 -- public symbols.
1502 -- The Map argument, if set to a non-empty Elist, specifies a set of
1503 -- mappings to be applied to entities in the tree. The map has the form:
1504 --
1505 -- old entity 1
1506 -- new entity to replace references to entity 1
1507 -- old entity 2
1508 -- new entity to replace references to entity 2
1509 -- ...
1510 --
1511 -- The call destroys the contents of Map in this case
1512 --
1513 -- The parameter New_Sloc, if set to a value other than No_Location, is
1514 -- used as the Sloc value for all nodes in the new copy. If New_Sloc is
1515 -- set to its default value No_Location, then the Sloc values of the
1516 -- nodes in the copy are simply copied from the corresponding original.
1517 --
1518 -- The Comes_From_Source indication is unchanged if New_Sloc is set to
1519 -- the default No_Location value, but is reset if New_Sloc is given, since
1520 -- in this case the result clearly is neither a source node or an exact
1521 -- copy of a source node.
1522 --
1523 -- The parameter New_Scope, if set to a value other than Empty, is the
1524 -- value to use as the Scope for any Itypes that are copied. The most
1525 -- typical value for this parameter, if given, is Current_Scope.
1527 function New_External_Entity
1535 -- This function creates an N_Defining_Identifier node for an internal
1536 -- created entity, such as an implicit type or subtype, or a record
1537 -- initialization procedure. The entity name is constructed with a call
1538 -- to New_External_Name (Related_Id, Suffix, Suffix_Index, Prefix), so
1539 -- that the generated name may be referenced as a public entry, and the
1540 -- Is_Public flag is set if needed (using Set_Public_Status). If the
1541 -- entity is for a type or subtype, the size/align fields are initialized
1542 -- to unknown (Uint_0).
1544 function New_Internal_Entity
1549 -- This function is similar to New_External_Entity, except that the
1550 -- name is constructed by New_Internal_Name (Id_Char). This is used
1551 -- when the resulting entity does not have to be referenced as a
1552 -- public entity (and in this case Is_Public is not set).
1556 -- Next_Actual (N) is equivalent to N := Next_Actual (N). Note that we
1557 -- inline this procedural form, but not the functional form that follows.
1560 -- Find next actual parameter in declaration order. As described for
1561 -- First_Actual, this is the next actual in the declaration order, not
1562 -- the call order, so this does not correspond to simply taking the
1563 -- next entry of the Parameter_Associations list. The argument is an
1564 -- actual previously returned by a call to First_Actual or Next_Actual.
1565 -- Note that the result produced is always an expression, not a parameter
1566 -- association node, even if named notation was used.
1569 -- Tests if type T can be determined at compile time to have no scalar
1570 -- parts in the sense of the Valid_Scalars attribute. Returns True if
1571 -- this is the case, meaning that the result of Valid_Scalars is True.
1573 procedure Normalize_Actuals
1578 -- Reorders lists of actuals according to names of formals, value returned
1579 -- in Success indicates success of reordering. For more details, see body.
1580 -- Errors are reported only if Report is set to True.
1583 -- This routine is called if the sub-expression N maybe the target of
1584 -- an assignment (e.g. it is the left side of an assignment, used as
1585 -- an out parameters, or used as prefixes of access attributes). It
1586 -- sets May_Be_Modified in the associated entity if there is one,
1587 -- taking into account the rule that in the case of renamed objects,
1588 -- it is the flag in the renamed object that must be set.
1589 --
1590 -- The parameter Sure is set True if the modification is sure to occur
1591 -- (e.g. target of assignment, or out parameter), and to False if the
1592 -- modification is only potential (e.g. address of entity taken).
1595 -- [Ada 2012: AI05-0125-1]: If S is an inherited dispatching primitive S2,
1596 -- or overrides an inherited dispatching primitive S2, the original
1597 -- corresponding operation of S is the original corresponding operation of
1598 -- S2. Otherwise, it is S itself.
1601 -- Return the accessibility level of the view of the object Obj. For
1602 -- convenience, qualified expressions applied to object names are also
1603 -- allowed as actuals for this function.
1606 -- N is a pragma node or aspect specification node. This function returns
1607 -- the name of the pragma or aspect in original source form, taking into
1608 -- account possible rewrites, and also cases where a pragma comes from an
1609 -- aspect (in such cases, the name can be different from the pragma name,
1610 -- e.g. a Pre aspect generates a Precondition pragma). This also deals with
1611 -- the presence of 'Class, which results in one of the special names
1612 -- Name_uPre, Name_uPost, Name_uInvariant, or Name_uType_Invariant being
1613 -- returned to represent the corresponding aspects with x'Class names.
1616 -- Returns True if the names of both entities correspond with matching
1617 -- primitives. This routine includes support for the case in which one
1618 -- or both entities correspond with entities built by Derive_Subprogram
1619 -- with a special name to avoid being overridden (i.e. return true in case
1620 -- of entities with names "nameP" and "name" or vice versa).
1623 -- Returns some private component (if any) of the given Type_Id.
1624 -- Used to enforce the rules on visibility of operations on composite
1625 -- types, that depend on the full view of the component type. For a
1626 -- record type there may be several such components, we just return
1627 -- the first one.
1629 procedure Process_End_Label
1633 -- N is a node whose End_Label is to be processed, generating all
1634 -- appropriate cross-reference entries, and performing style checks
1635 -- for any identifier references in the end label. Typ is either
1636 -- 'e' or 't indicating the type of the cross-reference entity
1637 -- (e for spec, t for body, see Lib.Xref spec for details). The
1638 -- parameter Ent gives the entity to which the End_Label refers,
1639 -- and to which cross-references are to be generated.
1642 -- Determine whether entity Id is referenced within expression Expr
1645 -- Returns True if the expression Expr contains any references to a
1646 -- generic type. This can only happen within a generic template.
1649 -- Removes E from the homonym chain
1652 -- This is used to construct the second argument in a call to Rep_To_Pos
1653 -- which is Standard_True if range checks are enabled (E is an entity to
1654 -- which the Range_Checks_Suppressed test is applied), and Standard_False
1655 -- if range checks are suppressed. Loc is the location for the node that
1656 -- is returned (which is a New_Occurrence of the appropriate entity).
1657 --
1658 -- Note: one might think that it would be fine to always use True and
1659 -- to ignore the suppress in this case, but it is generally better to
1660 -- believe a request to suppress exceptions if possible, and further
1661 -- more there is at least one case in the generated code (the code for
1662 -- array assignment in a loop) that depends on this suppression.
1665 -- N is a node which should have an entity value if it is an entity name.
1666 -- If not, then check if there were previous errors. If so, just fill
1667 -- in with Any_Id and ignore. Otherwise signal a program error exception.
1668 -- This is used as a defense mechanism against ill-formed trees caused by
1669 -- previous errors (particularly in -gnatq mode).
1671 function Requires_State_Refinement
1674 -- Determine whether a package denoted by its spec and body entities
1675 -- requires refinement of abstract states.
1678 -- Id is a type entity. The result is True when temporaries of this type
1679 -- need to be wrapped in a transient scope to be reclaimed properly when a
1680 -- secondary stack is in use. Examples of types requiring such wrapping are
1681 -- controlled types and variable-sized types including unconstrained
1682 -- arrays.
1685 -- Reset the Analyzed flags in all nodes of the tree whose root is N
1688 -- Return true if Subp is a function that returns an unconstrained type
1690 function Safe_To_Capture_Value
1694 -- The caller is interested in capturing a value (either the current value,
1695 -- or an indication that the value is non-null) for the given entity Ent.
1696 -- This value can only be captured if sequential execution semantics can be
1697 -- properly guaranteed so that a subsequent reference will indeed be sure
1698 -- that this current value indication is correct. The node N is the
1699 -- construct which resulted in the possible capture of the value (this
1700 -- is used to check if we are in a conditional).
1701 --
1702 -- Cond is used to skip the test for being inside a conditional. It is used
1703 -- in the case of capturing values from if/while tests, which already do a
1704 -- proper job of handling scoping issues without this help.
1705 --
1706 -- The only entities whose values can be captured are OUT and IN OUT formal
1707 -- parameters, and variables unless Cond is True, in which case we also
1708 -- allow IN formals, loop parameters and constants, where we cannot ever
1709 -- capture actual value information, but we can capture conditional tests.
1712 -- Determine if two (possibly expanded) names are the same name. This is
1713 -- a purely syntactic test, and N1 and N2 need not be analyzed.
1716 -- Determine if Node1 and Node2 are known to designate the same object.
1717 -- This is a semantic test and both nodes must be fully analyzed. A result
1718 -- of True is decisively correct. A result of False does not necessarily
1719 -- mean that different objects are designated, just that this could not
1720 -- be reliably determined at compile time.
1723 -- Determines if T1 and T2 represent exactly the same type. Two types
1724 -- are the same if they are identical, or if one is an unconstrained
1725 -- subtype of the other, or they are both common subtypes of the same
1726 -- type with identical constraints. The result returned is conservative.
1727 -- It is True if the types are known to be the same, but a result of
1728 -- False is indecisive (e.g. the compiler may not be able to tell that
1729 -- two constraints are identical).
1732 -- Determines if Node1 and Node2 are known to be the same value, which is
1733 -- true if they are both compile time known values and have the same value,
1734 -- or if they are the same object (in the sense of function Same_Object).
1735 -- A result of False does not necessarily mean they have different values,
1736 -- just that it is not possible to determine they have the same value.
1739 -- Determines if the entity Scope1 is the same as Scope2, or if it is
1740 -- inside it, where both entities represent scopes. Note that scopes
1741 -- are only partially ordered, so Scope_Within_Or_Same (A,B) and
1742 -- Scope_Within_Or_Same (B,A) can both be False for a given pair A,B.
1745 -- Like Scope_Within_Or_Same, except that this function returns
1746 -- False in the case where Scope1 and Scope2 are the same scope.
1749 -- Same as Basic_Set_Convention, but with an extra check for access types.
1750 -- In particular, if E is an access-to-subprogram type, and Val is a
1751 -- foreign convention, then we set Can_Use_Internal_Rep to False on E.
1752 -- Also, if the Etype of E is set and is an anonymous access type with
1753 -- no convention set, this anonymous type inherits the convention of E.
1757 -- Establish the entity E as the currently visible definition of its
1758 -- associated name (i.e. the Node_Id associated with its name).
1761 -- Sets the Debug_Info_Needed flag on entity T , and also on any entities
1762 -- that are needed by T (for an object, the type of the object is needed,
1763 -- and for a type, various subsidiary types are needed -- see body for
1764 -- details). Never has any effect on T if the Debug_Info_Off flag is set.
1765 -- This routine should always be used instead of Set_Needs_Debug_Info to
1766 -- ensure that subsidiary entities are properly handled.
1769 -- This procedure has the same calling sequence as Set_Entity, but it
1770 -- performs additional checks as follows:
1771 --
1772 -- If Style_Check is set, then it calls a style checking routine which
1773 -- can check identifier spelling style. This procedure also takes care
1774 -- of checking the restriction No_Implementation_Identifiers.
1775 --
1776 -- If restriction No_Abort_Statements is set, then it checks that the
1777 -- entity is not Ada.Task_Identification.Abort_Task.
1778 --
1779 -- If restriction No_Dynamic_Attachment is set, then it checks that the
1780 -- entity is not one of the restricted names for this restriction.
1781 --
1782 -- If restriction No_Implementation_Identifiers is set, then it checks
1783 -- that the entity is not implementation defined.
1787 -- Sets the Entity_Id value associated with the given name, which is the
1788 -- Id of the innermost visible entity with the given name. See the body
1789 -- of package Sem_Ch8 for further details on the handling of visibility.
1792 -- The arguments may be parameter associations, whose descendants
1793 -- are the optional formal name and the actual parameter. Positional
1794 -- parameters are already members of a list, and do not need to be
1795 -- chained separately. See also First_Actual and Next_Actual.
1799 -- Sets Optimize_Alignment_Space/Time flags in E from current settings
1802 -- If an entity (visible or otherwise) is defined in a library
1803 -- package, or a package that is itself public, then this subprogram
1804 -- labels the entity public as well.
1807 -- N is the node for either a left hand side (Out_Param set to False),
1808 -- or an Out or In_Out parameter (Out_Param set to True). If there is
1809 -- an assignable entity being referenced, then the appropriate flag
1810 -- (Referenced_As_LHS if Out_Param is False, Referenced_As_Out_Parameter
1811 -- if Out_Param is True) is set True, and the other flag set False.
1814 -- Set the flag Is_Transient of the current scope
1818 -- Copies the Esize field and Has_Biased_Representation flag from sub(type)
1819 -- entity T2 to (sub)type entity T1. Also copies the Is_Unsigned_Type flag
1820 -- in the fixed-point and discrete cases, and also copies the alignment
1821 -- value from T2 to T1. It does NOT copy the RM_Size field, which must be
1822 -- separately set if this is required to be copied also.
1825 -- True if the current scope is transient
1828 -- This function analyzes the given expression node and then resolves it
1829 -- as Standard.Boolean. If the result is static, then Uint_1 or Uint_0 is
1830 -- returned corresponding to the value, otherwise an error message is
1831 -- output and No_Uint is returned.
1834 -- This function analyzes the given expression node and then resolves it
1835 -- as any integer type. If the result is static, then the value of the
1836 -- universal expression is returned, otherwise an error message is output
1837 -- and a value of No_Uint is returned.
1840 -- Return True if it can be statically determined that the Expressions
1841 -- E1 and E2 refer to different objects
1844 -- Determine whether node N is a loop statement subject to at least one
1845 -- 'Loop_Entry attribute.
1848 -- Return the accessibility level of the view denoted by Subp
1851 -- Return True if Typ supports the GCC built-in atomic operations (i.e. if
1852 -- Typ is properly sized and aligned).
1855 -- Print debugging information on entry to each unit being analyzed
1858 -- Move a list of entities from one scope to another, and recompute
1859 -- Is_Public based upon the new scope.
1862 -- Return the accessibility level of Typ
1864 function Type_Without_Stream_Operation
1867 -- AI05-0161: In Ada 2012, if the restriction No_Default_Stream_Attributes
1868 -- is active then we cannot generate stream subprograms for composite types
1869 -- with elementary subcomponents that lack user-defined stream subprograms.
1870 -- This predicate determines whether a type has such an elementary
1871 -- subcomponent. If Op is TSS_Null, a type that lacks either Read or Write
1872 -- prevents the construction of a composite stream operation. If Op is
1873 -- specified we check only for the given stream operation.
1876 -- Return the entity which represents declaration N, so that different
1877 -- views of the same entity have the same unique defining entity:
1878 -- * package spec and body;
1879 -- * subprogram declaration, subprogram stub and subprogram body;
1880 -- * private view and full view of a type;
1881 -- * private view and full view of a deferred constant.
1882 -- In other cases, return the defining entity for N.
1885 -- Return the unique entity for entity E, which would be returned by
1886 -- Unique_Defining_Entity if applied to the enclosing declaration of E.
1889 -- Return a unique name for entity E, which could be used to identify E
1890 -- across compilation units.
1893 -- Determine whether a compilation unit is visible in the current context,
1894 -- because there is a with_clause that makes the unit available. Used to
1895 -- provide better messages on common visiblity errors on operators.
1898 -- Yields Universal_Integer or Universal_Real if this is a candidate
1902 -- Removes any qualifications from Expr. For example, for T1'(T2'(X)), this
1903 -- returns X. If Expr is not a qualified expression, returns Expr.
1906 -- [Ada 2012:AI-0125-1]: Collect all the visible parents and progenitors
1907 -- of a type extension or private extension declaration. If the full-view
1908 -- of private parents and progenitors is available then it is used to
1909 -- generate the list of visible ancestors; otherwise their partial
1910 -- view is added to the resulting list.
1913 -- Determines if Current_Scope is within an init proc
1916 -- Returns True if entity Id is declared within scope S
1919 -- Output error message for incorrectly typed expression. Expr is the node
1920 -- for the incorrectly typed construct (Etype (Expr) is the type found),
1921 -- and Expected_Type is the entity for the expected type. Note that Expr
1922 -- does not have to be a subexpression, anything with an Etype field may
1923 -- be used.