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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) 1992-2015, 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
40 -- Given a type that implements interfaces look for its associated
41 -- definition node and return its list of interfaces.
44 -- Add A to the list of access types to process when expanding the
45 -- freeze node of E.
48 -- Given a block statement N, generate an internal E_Block label and make
49 -- it the identifier of the block. Id denotes the generated entity. If the
50 -- block already has an identifier, Id returns the entity of its label.
53 -- Add pragma Prag to the contract of an entry, a package [body], a
54 -- subprogram [body] or variable denoted by Id. The following are valid
55 -- pragmas:
56 -- Abstract_States
57 -- Async_Readers
58 -- Async_Writers
59 -- Contract_Cases
60 -- Depends
61 -- Effective_Reads
62 -- Effective_Writes
63 -- Extensions_Visible
64 -- Global
65 -- Initial_Condition
66 -- Initializes
67 -- Part_Of
68 -- Postcondition
69 -- Precondition
70 -- Refined_Depends
71 -- Refined_Global
72 -- Refined_Post
73 -- Refined_States
74 -- Test_Case
77 -- These procedures adds a declaration N at the library level, to be
78 -- elaborated before any other code in the unit. It is used for example
79 -- for the entity that marks whether a unit has been elaborated. The
80 -- declaration is added to the Declarations list of the Aux_Decls_Node
81 -- for the current unit. The declarations are added in the current scope,
82 -- so the caller should push a new scope as required before the call.
85 -- Given two types, returns True if we are in Allow_Integer_Address mode
86 -- and one of the types is (a descendent of) System.Address (and this type
87 -- is private), and the other type is any integer type.
92 -- Returns True if the value of V is the word size or an addressable factor
93 -- of the word size (typically 8, 16, 32 or 64).
95 procedure Aggregate_Constraint_Checks
98 -- Checks expression Exp against subtype Check_Typ. If Exp is an aggregate
99 -- and Check_Typ a constrained record type with discriminants, we generate
100 -- the appropriate discriminant checks. If Exp is an array aggregate then
101 -- emit the appropriate length checks. If Exp is a scalar type, or a string
102 -- literal, Exp is changed into Check_Typ'(Exp) to ensure that range checks
103 -- are performed at run time. Also used for expressions in the argument of
104 -- 'Update, which shares some of the features of an aggregate.
107 -- If the alignment of the type or object E is currently known to the
108 -- compiler, then this function returns the alignment value in bits.
109 -- Otherwise Uint_0 is returned, indicating that the alignment of the
110 -- entity is not yet known to the compiler.
113 -- If the parent of the operation is declared in the visible part of
114 -- the current scope, the inherited operation is visible even though the
115 -- derived type that inherits the operation may be completed in the private
116 -- part of the current package.
118 procedure Apply_Compile_Time_Constraint_Error
127 -- N is a subexpression which will raise constraint error when evaluated
128 -- at runtime. Msg is a message that explains the reason for raising the
129 -- exception. The last character is ? if the message is always a warning,
130 -- even in Ada 95, and is not a ? if the message represents an illegality
131 -- (because of violation of static expression rules) in Ada 95 (but not
132 -- in Ada 83). Typically this routine posts all messages at the Sloc of
133 -- node N. However, if Loc /= No_Location, Loc is the Sloc used to output
134 -- the message. After posting the appropriate message, and if the flag
135 -- Rep is set, this routine replaces the expression with an appropriate
136 -- N_Raise_Constraint_Error node using the given Reason code. This node
137 -- is then marked as being static if the original node is static, but
138 -- sets the flag Raises_Constraint_Error, preventing further evaluation.
139 -- The error message may contain a } or & insertion character. This
140 -- normally references Etype (N), unless the Ent argument is given
141 -- explicitly, in which case it is used instead. The type of the raise
142 -- node that is built is normally Etype (N), but if the Typ parameter
143 -- is present, this is used instead. Warn is normally False. If it is
144 -- True then the message is treated as a warning even though it does
145 -- not end with a ? (this is used when the caller wants to parameterize
146 -- whether an error or warning is given).
149 -- Given the entity of an abstract state or a variable, determine whether
150 -- Id is subject to external property Async_Readers and if it is, the
151 -- related expression evaluates to True.
154 -- Given the entity of an abstract state or a variable, determine whether
155 -- Id is subject to external property Async_Writers and if it is, the
156 -- related expression evaluates to True.
159 -- If at the point of declaration an array type has a private or limited
160 -- component, several array operations are not avaiable on the type, and
161 -- the array type is flagged accordingly. If in the immediate scope of
162 -- the array type the component becomes non-private or non-limited, these
163 -- operations become avaiable. This can happen if the scopes of both types
164 -- are open, and the scope of the array is not outside the scope of the
165 -- component.
167 procedure Bad_Attribute
171 -- Called when node N is expected to contain a valid attribute name, and
172 -- Nam is found instead. If Warn is set True this is a warning, else this
173 -- is an error.
175 procedure Bad_Predicated_Subtype_Use
180 -- This is called when Typ, a predicated subtype, is used in a context
181 -- which does not allow the use of a predicated subtype. Msg is passed to
182 -- Error_Msg_FE to output an appropriate message using N as the location,
183 -- and Typ as the entity. The caller must set up any insertions other than
184 -- the & for the type itself. Note that if Typ is a generic actual type,
185 -- then the message will be output as a warning, and a raise Program_Error
186 -- is inserted using Insert_Action with node N as the insertion point. Node
187 -- N also supplies the source location for construction of the raise node.
188 -- If Typ does not have any predicates, the call has no effect. Set flag
189 -- Suggest_Static when the context warrants an advice on how to avoid the
190 -- use error.
192 function Bad_Unordered_Enumeration_Reference
195 -- Node N contains a potentially dubious reference to type T, either an
196 -- explicit comparison, or an explicit range. This function returns True
197 -- if the type T is an enumeration type for which No pragma Order has been
198 -- given, and the reference N is not in the same extended source unit as
199 -- the declaration of T.
201 function Build_Actual_Subtype
204 -- Build an anonymous subtype for an entity or expression, using the
205 -- bounds of the entity or the discriminants of the enclosing record.
206 -- T is the type for which the actual subtype is required, and N is either
207 -- a defining identifier, or any subexpression.
209 function Build_Actual_Subtype_Of_Component
212 -- Determine whether a selected component has a type that depends on
213 -- discriminants, and build actual subtype for it if so.
215 function Build_Default_Init_Cond_Call
219 -- Build a call to the default initial condition procedure of type Typ with
220 -- Obj_Id as the actual parameter.
223 -- Inspect the contents of private declarations Priv_Decls and build the
224 -- bodies the default initial condition procedures for all types subject
225 -- to pragma Default_Initial_Condition.
228 -- If private type Typ is subject to pragma Default_Initial_Condition,
229 -- build the declaration of the procedure which verifies the assumption
230 -- of the pragma at runtime. The declaration is inserted after the related
231 -- pragma.
233 function Build_Default_Subtype
236 -- If T is an unconstrained type with defaulted discriminants, build a
237 -- subtype constrained by the default values, insert the subtype
238 -- declaration in the tree before N, and return the entity of that
239 -- subtype. Otherwise, simply return T.
241 function Build_Discriminal_Subtype_Of_Component
243 -- Determine whether a record component has a type that depends on
244 -- discriminants, and build actual subtype for it if so.
247 -- Given a compilation unit node N, allocate an elaboration counter for
248 -- the compilation unit, and install it in the Elaboration_Entity field
249 -- of Spec_Id, the entity for the compilation unit.
251 procedure Build_Explicit_Dereference
254 -- AI05-139: Names with implicit dereference. If the expression N is a
255 -- reference type and the context imposes the corresponding designated
256 -- type, convert N into N.Disc.all. Such expressions are always over-
257 -- loaded with both interpretations, and the dereference interpretation
258 -- carries the name of the reference discriminant.
261 -- Returns True if the expression cannot possibly raise Constraint_Error.
262 -- The response is conservative in the sense that a result of False does
263 -- not necessarily mean that CE could be raised, but a response of True
264 -- means that for sure CE cannot be raised.
266 procedure Check_Dynamically_Tagged_Expression
270 -- Check wrong use of dynamically tagged expression
273 -- Verify that the full declaration of type T has been seen. If not, place
274 -- error message on node N. Used in object declarations, type conversions
275 -- and qualified expressions.
278 -- (Ada 2012): If the construct N has two or more direct constituents that
279 -- are names or expressions whose evaluation may occur in an arbitrary
280 -- order, at least one of which contains a function call with an in out or
281 -- out parameter, then the construct is legal only if: for each name that
282 -- is passed as a parameter of mode in out or out to some inner function
283 -- call C2 (not including the construct N itself), there is no other name
284 -- anywhere within a direct constituent of the construct C other than
285 -- the one containing C2, that is known to refer to the same object (RM
286 -- 6.4.1(6.17/3)).
289 -- AI05-139-2: Accessors and iterators for containers. This procedure
290 -- checks whether T is a reference type, and if so it adds an interprettion
291 -- to N whose type is the designated type of the reference_discriminant.
292 -- If N is a generalized indexing operation, the interpretation is added
293 -- both to the corresponding function call, and to the indexing node.
296 -- Within a protected function, the current object is a constant, and
297 -- internal calls to a procedure or entry are illegal. Similarly, other
298 -- uses of a protected procedure in a renaming or a generic instantiation
299 -- in the context of a protected function are illegal (AI05-0225).
301 procedure Check_Later_Vs_Basic_Declarations
304 -- If During_Parsing is True, check for misplacement of later vs basic
305 -- declarations in Ada 83. If During_Parsing is False, and the SPARK
306 -- restriction is set, do the same: although SPARK 95 removes the
307 -- distinction between initial and later declarative items, the distinction
308 -- remains in the Examiner (JB01-005). Note that the Examiner does not
309 -- count package declarations in later declarative items.
312 -- Check whether Ent denotes an entity declared in an uplevel scope, which
313 -- is accessed inside a nested procedure, and set the Has_Uplevel_Reference
314 -- flag accordingly. This is currently only enabled for if on a VM target,
315 -- or if Opt.Unnest_Subprogram_Mode is active. N is the node for the
316 -- possible uplevel reference.
319 -- Determine whether object or state Id introduces a hidden state. If this
320 -- is the case, emit an error.
323 -- N is one of the statement forms that is a potentially blocking
324 -- operation. If it appears within a protected action, emit warning.
327 -- Determine whether the contract of subprogram Subp_Id mentions attribute
328 -- 'Result and it contains an expression that evaluates differently in pre-
329 -- and post-state.
331 procedure Check_Unprotected_Access
334 -- Check whether the expression is a pointer to a protected component,
335 -- and the context is external to the protected operation, to warn against
336 -- a possible unlocked access to data.
338 procedure Collect_Interfaces
343 -- Ada 2005 (AI-251): Collect whole list of abstract interfaces that are
344 -- directly or indirectly implemented by T. Exclude_Parents is used to
345 -- avoid the addition of inherited interfaces to the generated list.
346 -- Use_Full_View is used to collect the interfaces using the full-view
347 -- (if available).
349 procedure Collect_Interface_Components
352 -- Ada 2005 (AI-251): Collect all the tag components associated with the
353 -- secondary dispatch tables of a tagged type.
355 procedure Collect_Interfaces_Info
360 -- Ada 2005 (AI-251): Collect all the interfaces associated with T plus
361 -- the record component and tag associated with each of these interfaces.
362 -- On exit Ifaces_List, Components_List and Tags_List have the same number
363 -- of elements, and elements at the same position on these tables provide
364 -- information on the same interface type.
366 procedure Collect_Parents
370 -- Collect all the parents of Typ. Use_Full_View is used to collect them
371 -- using the full-view of private parents (if available).
374 -- Called upon type derivation and extension. We scan the declarative part
375 -- in which the type appears, and collect subprograms that have one
376 -- subsidiary subtype of the type. These subprograms can only appear after
377 -- the type itself.
379 function Compile_Time_Constraint_Error
385 -- This is similar to Apply_Compile_Time_Constraint_Error in that it
386 -- generates a warning (or error) message in the same manner, but it does
387 -- not replace any nodes. For convenience, the function always returns its
388 -- first argument. The message is a warning if the message ends with ?, or
389 -- we are operating in Ada 83 mode, or the Warn parameter is set to True.
392 -- Sets the Has_Delayed_Freeze flag of New if the Delayed_Freeze flag of
393 -- Old is set and Old has no yet been Frozen (i.e. Is_Frozen is false).
396 -- Determine whether pragma Prag contains a reference to the entity of an
397 -- abstract state with a visible refinement. Prag must denote one of the
398 -- following pragmas:
399 -- Depends
400 -- Global
403 -- Utility to create a parameter profile for a new subprogram spec, when
404 -- the subprogram has a body that acts as spec. This is done for some cases
405 -- of inlining, and for private protected ops. Also used to create bodies
406 -- for stubbed subprograms.
408 function Copy_Component_List
411 -- Copy components from record type R_Typ that come from source. Used to
412 -- create a new compatible record type. Loc is the source location assigned
413 -- to the created nodes.
416 -- If a type is a generic actual type, return the corresponding formal in
417 -- the generic parent unit. There is no direct link in the tree for this
418 -- attribute, except in the case of formal private and derived types.
419 -- Possible optimization???
422 -- Return the corresponding spec of Subp_Decl when it denotes a body [stub]
423 -- or the defining entity of subprogram declaration Subp_Decl in all other
424 -- cases.
428 -- Find the currently visible definition for a given identifier, that is to
429 -- say the first entry in the visibility chain for the Chars of N.
432 -- Find whether there is a previous definition for identifier N in the
433 -- current scope. Because declarations for a scope are not necessarily
434 -- contiguous (e.g. for packages) the first entry on the visibility chain
435 -- for N is not necessarily in the current scope.
438 -- Get entity representing current scope
441 -- Returns current enclosing subprogram. If Current_Scope is a subprogram,
442 -- then that is what is returned, otherwise the Enclosing_Subprogram of the
443 -- Current_Scope is returned. The returned value is Empty if this is called
444 -- from a library package which is not within any subprogram.
447 -- Same as Type_Access_Level, except that if the type is the type of an Ada
448 -- 2012 stand-alone object of an anonymous access type, then return the
449 -- static accesssibility level of the object. In that case, the dynamic
450 -- accessibility level of the object may take on values in a range. The low
451 -- bound of of that range is returned by Type_Access_Level; this function
452 -- yields the high bound of that range. Also differs from Type_Access_Level
453 -- in the case of a descendant of a generic formal type (returns Int'Last
454 -- instead of 0).
457 -- Given a declaration N, returns the associated defining entity. If the
458 -- declaration has a specification, the entity is obtained from the
459 -- specification. If the declaration has a defining unit name, then the
460 -- defining entity is obtained from the defining unit name ignoring any
461 -- child unit prefixes.
462 --
463 -- Iterator loops also have a defining entity, which holds the list of
464 -- local entities declared during loop expansion. These entities need
465 -- debugging information, generated through Qualify_Entity_Names, and
466 -- the loop declaration must be placed in the table Name_Qualify_Units.
468 function Denotes_Discriminant
471 -- Returns True if node N is an Entity_Name node for a discriminant. If the
472 -- flag Check_Concurrent is true, function also returns true when N denotes
473 -- the discriminal of the discriminant of a concurrent type. This is needed
474 -- to disable some optimizations on private components of protected types,
475 -- and constraint checks on entry families constrained by discriminants.
478 -- Detect suspicious overlapping between actuals in a call, when both are
479 -- writable (RM 2012 6.4.1(6.4/3))
482 -- Functions to detect suspicious overlapping between actuals in a call,
483 -- when one of them is writable. The predicates are those proposed in
484 -- AI05-0144, to detect dangerous order dependence in complex calls.
485 -- I would add a parameter Warn which enables more extensive testing of
486 -- cases as we find appropriate when we are only warning ??? Or perhaps
487 -- return an indication of (Error, Warn, OK) ???
490 -- Returns True if node N denotes a single variable without parentheses
493 -- Returns True if N denotes a discriminant or if N is a range, a subtype
494 -- indication or a scalar subtype where one of the bounds is a
495 -- discriminant.
497 function Designate_Same_Unit
500 -- Returns True if Name1 and Name2 designate the same unit name; each of
501 -- these names is supposed to be a selected component name, an expanded
502 -- name, a defining program unit name or an identifier.
505 -- Expr should be an expression of an access type. Builds an integer
506 -- literal except in cases involving anonymous access types where
507 -- accessibility levels are tracked at runtime (access parameters and Ada
508 -- 2012 stand-alone objects).
511 -- Same as Einfo.Extra_Accessibility except thtat object renames
512 -- are looked through.
515 -- Given the entity of an abstract state or a variable, determine whether
516 -- Id is subject to external property Effective_Reads and if it is, the
517 -- related expression evaluates to True.
520 -- Given the entity of an abstract state or a variable, determine whether
521 -- Id is subject to external property Effective_Writes and if it is, the
522 -- related expression evaluates to True.
525 -- Returns the enclosing N_Compilation_Unit Node that is the root of a
526 -- subtree containing N.
529 -- Returns the closest ancestor of Typ that is a CPP type.
531 function Enclosing_Generic_Body
533 -- Returns the Node_Id associated with the innermost enclosing generic
534 -- body, if any. If none, then returns Empty.
536 function Enclosing_Generic_Unit
538 -- Returns the Node_Id associated with the innermost enclosing generic
539 -- unit, if any. If none, then returns Empty.
541 function Enclosing_Lib_Unit_Entity
543 -- Returns the entity of enclosing library unit node which is the
544 -- root of the current scope (which must not be Standard_Standard, and the
545 -- caller is responsible for ensuring this condition) or other specified
546 -- entity.
549 -- Utility function to return the Ada entity of the package enclosing
550 -- the entity E, if any. Returns Empty if no enclosing package.
553 -- Utility function to return the Ada entity of the subprogram enclosing
554 -- the entity E, if any. Returns Empty if no enclosing subprogram.
557 -- Make sure a freeze node is allocated for entity E. If necessary, build
558 -- and initialize a new freeze node and set Has_Delayed_Freeze True for E.
561 -- Insert new name in symbol table of current scope with check for
562 -- duplications (error message is issued if a conflict is found).
563 -- Note: Enter_Name is not used for overloadable entities, instead these
564 -- are entered using Sem_Ch6.Enter_Overloadable_Entity.
567 -- Return the entity of N or Empty. If N is a renaming, return the entity
568 -- of the root renamed object.
571 -- This procedure is called after issuing a message complaining about an
572 -- inappropriate use of limited type T. If useful, it adds additional
573 -- continuation lines to the message explaining why type T is limited.
574 -- Messages are placed at node N.
578 -- Extensions_Visible does not yield a mode when SPARK_Mode is off. This
579 -- value acts as a default in a non-SPARK compilation.
581 Extensions_Visible_False,
582 -- A value of "False" signifies that Extensions_Visible is either
583 -- missing or the pragma is present and the value of its Boolean
584 -- expression is False.
586 Extensions_Visible_True);
587 -- A value of "True" signifies that Extensions_Visible is present and
588 -- the value of its Boolean expression is True.
590 function Extensions_Visible_Status
592 -- Given the entity of a subprogram or formal parameter subject to pragma
593 -- Extensions_Visible, return the Boolean value denoted by the expression
594 -- of the pragma.
596 procedure Find_Actual
600 -- Determines if the node N is an actual parameter of a function of a
601 -- procedure call. If so, then Formal points to the entity for the formal
602 -- (Ekind is E_In_Parameter, E_Out_Parameter, or E_In_Out_Parameter) and
603 -- Call is set to the node for the corresponding call. If the node N is not
604 -- an actual parameter then Formal and Call are set to Empty.
607 -- Find specific type of a class-wide type, and handle the case of an
608 -- incomplete type coming either from a limited_with clause or from an
609 -- incomplete type declaration. If resulting type is private return its
610 -- full view.
612 function Find_Body_Discriminal
614 -- Given a discriminant of the record type that implements a task or
615 -- protected type, return the discriminal of the corresponding discriminant
616 -- of the actual concurrent type.
618 function Find_Corresponding_Discriminant
621 -- Because discriminants may have different names in a generic unit and in
622 -- an instance, they are resolved positionally when possible. A reference
623 -- to a discriminant carries the discriminant that it denotes when it is
624 -- analyzed. Subsequent uses of this id on a different type denotes the
625 -- discriminant at the same position in this new type.
628 -- Given an arbitrary entity, try to find the nearest enclosing iterator
629 -- loop. If such a loop is found, return the entity of its identifier (the
630 -- E_Loop scope), otherwise return Empty.
633 -- Find the nested loop statement in a conditional block. Loops subject to
634 -- attribute 'Loop_Entry are transformed into blocks. Parts of the original
635 -- loop are nested within the block.
637 procedure Find_Overlaid_Entity
641 -- The node N should be an address representation clause. Determines if
642 -- the target expression is the address of an entity with an optional
643 -- offset. If so, set Ent to the entity and, if there is an offset, set
644 -- Off to True, otherwise to False. If N is not an address representation
645 -- clause, or if it is not possible to determine that the address is of
646 -- this form, then set Ent to Empty.
649 -- Return the type of formal parameter Param as determined by its
650 -- specification.
652 -- The following type describes the placement of an arbitrary entity with
653 -- respect to SPARK visible / hidden state space.
657 -- An entity is not in the visible, private or body state space when
658 -- the immediate enclosing construct is not a package.
660 Visible_State_Space,
661 -- An entity is in the visible state space when it appears immediately
662 -- within the visible declarations of a package or when it appears in
663 -- the visible state space of a nested package which in turn is declared
664 -- in the visible declarations of an enclosing package:
666 -- package Pack is
667 -- Visible_Variable : ...
668 -- package Nested
669 -- with Abstract_State => Visible_State
670 -- is
671 -- Visible_Nested_Variable : ...
672 -- end Nested;
673 -- end Pack;
675 -- Entities associated with a package instantiation inherit the state
676 -- space from the instance placement:
678 -- generic
679 -- package Gen is
680 -- Generic_Variable : ...
681 -- end Gen;
683 -- with Gen;
684 -- package Pack is
685 -- package Inst is new Gen;
686 -- -- Generic_Variable is in the visible state space of Pack
687 -- end Pack;
689 Private_State_Space,
690 -- An entity is in the private state space when it appears immediately
691 -- within the private declarations of a package or when it appears in
692 -- the visible state space of a nested package which in turn is declared
693 -- in the private declarations of an enclosing package:
695 -- package Pack is
696 -- private
697 -- Private_Variable : ...
698 -- package Nested
699 -- with Abstract_State => Private_State
700 -- is
701 -- Private_Nested_Variable : ...
702 -- end Nested;
703 -- end Pack;
705 -- The same placement principle applies to package instantiations
707 Body_State_Space);
708 -- An entity is in the body state space when it appears immediately
709 -- within the declarations of a package body or when it appears in the
710 -- visible state space of a nested package which in turn is declared in
711 -- the declarations of an enclosing package body:
713 -- package body Pack is
714 -- Body_Variable : ...
715 -- package Nested
716 -- with Abstract_State => Body_State
717 -- is
718 -- Body_Nested_Variable : ...
719 -- end Nested;
720 -- end Pack;
722 -- The same placement principle applies to package instantiations
724 procedure Find_Placement_In_State_Space
728 -- Determine the state space placement of an item. Item_Id denotes the
729 -- entity of an abstract state, variable or package instantiation.
730 -- Placement captures the precise placement of the item in the enclosing
731 -- state space. If the state space is that of a package, Pack_Id denotes
732 -- its entity, otherwise Pack_Id is Empty.
735 -- N is a case statement whose expression is a compile-time value.
736 -- Determine the alternative chosen, so that the code of non-selected
737 -- alternatives, and the warnings that may apply to them, are removed.
740 -- Node is an N_Function_Call or N_Procedure_Call_Statement node. The
741 -- result returned is the first actual parameter in declaration order
742 -- (not the order of parameters as they appeared in the source, which
743 -- can be quite different as a result of the use of named parameters).
744 -- Empty is returned for a call with no parameters. The procedure for
745 -- iterating through the actuals in declaration order is to use this
746 -- function to find the first actual, and then use Next_Actual to obtain
747 -- the next actual in declaration order. Note that the value returned
748 -- is always the expression (not the N_Parameter_Association nodes,
749 -- even if named association is used).
751 procedure Gather_Components
757 -- The purpose of this procedure is to gather the valid components in a
758 -- record type according to the values of its discriminants, in order to
759 -- validate the components of a record aggregate.
760 --
761 -- Typ is the type of the aggregate when its constrained discriminants
762 -- need to be collected, otherwise it is Empty.
763 --
764 -- Comp_List is an N_Component_List node.
765 --
766 -- Governed_By is a list of N_Component_Association nodes, where each
767 -- choice list contains the name of a discriminant and the expression
768 -- field gives its value. The values of the discriminants governing
769 -- the (possibly nested) variant parts in Comp_List are found in this
770 -- Component_Association List.
771 --
772 -- Into is the list where the valid components are appended. Note that
773 -- Into need not be an Empty list. If it's not, components are attached
774 -- to its tail.
775 --
776 -- Report_Errors is set to True if the values of the discriminants are
777 -- non-static.
778 --
779 -- This procedure is also used when building a record subtype. If the
780 -- discriminant constraint of the subtype is static, the components of the
781 -- subtype are only those of the variants selected by the values of the
782 -- discriminants. Otherwise all components of the parent must be included
783 -- in the subtype for semantic analysis.
786 -- Given a node for an expression, obtain the actual subtype of the
787 -- expression. In the case of a parameter where the formal is an
788 -- unconstrained array or discriminated type, this will be the previously
789 -- constructed subtype of the actual. Note that this is not quite the
790 -- "Actual Subtype" of the RM, since it is always a constrained type, i.e.
791 -- it is the subtype of the value of the actual. The actual subtype is also
792 -- returned in other cases where it has already been constructed for an
793 -- object. Otherwise the expression type is returned unchanged, except for
794 -- the case of an unconstrained array type, where an actual subtype is
795 -- created, using Insert_Actions if necessary to insert any associated
796 -- actions.
799 -- This is like Get_Actual_Subtype, except that it never constructs an
800 -- actual subtype. If an actual subtype is already available, i.e. the
801 -- Actual_Subtype field of the corresponding entity is set, then it is
802 -- returned. Otherwise the Etype of the node is returned.
805 -- Return the body node for a stub (subprogram or package)
807 function Get_Cursor_Type
810 -- Find Cursor type in scope of formal container Typ, by locating primitive
811 -- operation First. For use in resolving the other primitive operations
812 -- of an Iterable type and expanding loops and quantified expressions
813 -- over formal containers.
816 -- This is used to construct the string literal node representing a
817 -- default external name, i.e. one that is constructed from the name of an
818 -- entity, or (in the case of extended DEC import/export pragmas, an
819 -- identifier provided as the external name. Letters in the name are
820 -- according to the setting of Opt.External_Name_Default_Casing.
823 -- If expression N references a part of an object, return this object.
824 -- Otherwise return Empty. Expression N should have been resolved already.
827 -- Returns the true generic entity in an instantiation. If the name in the
828 -- instantiation is a renaming, the function returns the renamed generic.
831 -- Implements the notion introduced ever-so briefly in RM 7.3.1 (5.2/3):
832 -- in a child unit a derived type is within the derivation class of an
833 -- ancestor declared in a parent unit, even if there is an intermediate
834 -- derivation that does not see the full view of that ancestor.
837 -- This procedure assigns to L and H respectively the values of the low and
838 -- high bounds of node N, which must be a range, subtype indication, or the
839 -- name of a scalar subtype. The result in L, H may be set to Error if
840 -- there was an earlier error in the range.
842 function Get_Enum_Lit_From_Pos
846 -- This function returns an identifier denoting the E_Enumeration_Literal
847 -- entity for the specified value from the enumeration type or subtype T.
848 -- The second argument is the Pos value, which is assumed to be in range.
849 -- The third argument supplies a source location for constructed nodes
850 -- returned by this function.
852 function Get_Iterable_Type_Primitive
855 -- Retrieve one of the primitives First, Next, Has_Element, Element from
856 -- the value of the Iterable aspect of a formal type.
859 -- Retrieve the fully expanded name of the library unit declared by
860 -- Decl_Node into the name buffer.
864 -- An entity value is associated with each name in the name table. The
865 -- Get_Name_Entity_Id function fetches the Entity_Id of this entity, which
866 -- is the innermost visible entity with the given name. See the body of
867 -- Sem_Ch8 for further details on handling of entity visibility.
870 -- Return the Name component of Test_Case pragma N
871 -- Bad name now that this no longer applies to Contract_Case ???
874 -- Get defining entity of parent unit of a child unit. In most cases this
875 -- is the defining entity of the unit, but for a child instance whose
876 -- parent needs a body for inlining, the instantiation node of the parent
877 -- has not yet been rewritten as a package declaration, and the entity has
878 -- to be retrieved from the Instance_Spec of the unit.
882 -- Obtains the Pragma_Id from the Chars field of Pragma_Identifier (N)
885 -- Recursive routine to analyze reason argument for pragma Warnings. The
886 -- value of the reason argument is appended to the current string using
887 -- Store_String_Chars. The reason argument is expected to be a string
888 -- literal or concatenation of string literals. An error is given for
889 -- any other form.
892 -- Given a node, return the renamed object if the node represents a renamed
893 -- object, otherwise return the node unchanged. The node may represent an
894 -- arbitrary expression.
897 -- Given an entity for an exception, package, subprogram or generic unit,
898 -- returns the ultimately renamed entity if this is a renaming. If this is
899 -- not a renamed entity, returns its argument. It is an error to call this
900 -- with any other kind of entity.
903 -- Nod is either a procedure call statement, or a function call, or an
904 -- accept statement node. This procedure finds the Entity_Id of the related
905 -- subprogram or entry and returns it, or if no subprogram can be found,
906 -- returns Empty.
909 -- Given the entity for a subprogram (E_Function or E_Procedure), return
910 -- the corresponding N_Subprogram_Body node. If the corresponding body
911 -- is missing (as for an imported subprogram), return Empty.
915 -- Given an entity for a task type or subtype, retrieves the
916 -- Task_Body_Procedure field from the corresponding task type declaration.
919 -- Returns true if type or subtype T is an access type, or has a component
920 -- (at any recursive level) that is an access type. This is a conservative
921 -- predicate, if it is not known whether or not T contains access values
922 -- (happens for generic formals in some cases), then False is returned.
923 -- Note that tagged types return False. Even though the tag is implemented
924 -- as an access type internally, this function tests only for access types
925 -- known to the programmer. See also Has_Tagged_Component.
928 -- Simple predicate to test for defaulted discriminants
931 -- Result of Has_Compatible_Alignment test, description found below. Note
932 -- that the values are arranged in increasing order of problematicness.
934 function Has_Compatible_Alignment
937 -- Obj is an object entity, and expr is a node for an object reference. If
938 -- the alignment of the object referenced by Expr is known to be compatible
939 -- with the alignment of Obj (i.e. is larger or the same), then the result
940 -- is Known_Compatible. If the alignment of the object referenced by Expr
941 -- is known to be less than the alignment of Obj, then Known_Incompatible
942 -- is returned. If neither condition can be reliably established at compile
943 -- time, then Unknown is returned. This is used to determine if alignment
944 -- checks are required for address clauses, and also whether copies must
945 -- be made when objects are passed by reference.
946 --
947 -- Note: Known_Incompatible does not mean that at run time the alignment
948 -- of Expr is known to be wrong for Obj, just that it can be determined
949 -- that alignments have been explicitly or implicitly specified which are
950 -- incompatible (whereas Unknown means that even this is not known). The
951 -- appropriate reaction of a caller to Known_Incompatible is to treat it as
952 -- Unknown, but issue a warning that there may be an alignment error.
955 -- Determines if the node can have declarations
958 -- Determines if the floating-point type E supports denormal numbers.
959 -- Returns False if E is not a floating-point type.
961 function Has_Discriminant_Dependent_Constraint
963 -- Returns True if and only if Comp has a constrained subtype that depends
964 -- on a discriminant.
967 -- Determines if the range of the floating-point type E includes
968 -- infinities. Returns False if E is not a floating-point type.
970 function Has_Interfaces
973 -- Where T is a concurrent type or a record type, returns true if T covers
974 -- any abstract interface types. In case of private types the argument
975 -- Use_Full_View controls if the check is done using its full view (if
976 -- available).
979 -- This is a simple minded function for determining whether an expression
980 -- has no obvious side effects. It is used only for determining whether
981 -- warnings are needed in certain situations, and is not guaranteed to
982 -- be accurate in either direction. Exceptions may mean an expression
983 -- does in fact have side effects, but this may be ignored and True is
984 -- returned, or a complex expression may in fact be side effect free
985 -- but we don't recognize it here and return False. The Side_Effect_Free
986 -- routine in Remove_Side_Effects is much more extensive and perhaps could
987 -- be shared, so that this routine would be more accurate.
990 -- Determine whether node N has a null exclusion
993 -- Predicate to determine whether a controlled type has a user-defined
994 -- Initialize primitive (and, in Ada 2012, whether that primitive is
995 -- non-null), which causes the type to not have preelaborable
996 -- initialization.
999 -- Return True iff type E has preelaborable initialization as defined in
1000 -- Ada 2005 (see AI-161 for details of the definition of this attribute).
1003 -- Check if a type has a (sub)component of a private type that has not
1004 -- yet received a full declaration.
1007 -- Determines if the floating-point type E supports signed zeros.
1008 -- Returns False if E is not a floating-point type.
1011 -- Determine whether subprogram [body] Subp_Id has a significant contract.
1012 -- All subprograms have a N_Contract node, but this does not mean that the
1013 -- contract is useful.
1016 -- Return whether an array type has static bounds
1019 -- Tests if type T is derived from Ada.Streams.Root_Stream_Type, or in the
1020 -- case of a composite type, has a component for which this predicate is
1021 -- True, and if so returns True. Otherwise a result of False means that
1022 -- there is no Stream type in sight. For a private type, the test is
1023 -- applied to the underlying type (or returns False if there is no
1024 -- underlying type).
1027 -- Returns true if the last character of E is Suffix. Used in Assertions.
1030 -- Returns the name of E adding Suffix
1033 -- Returns the name of E without Suffix
1036 -- Returns True if Typ is a composite type (array or record) which is
1037 -- either itself a tagged type, or has a component (recursively) which is
1038 -- a tagged type. Returns False for non-composite type, or if no tagged
1039 -- component is present. This function is used to check if "=" has to be
1040 -- expanded into a bunch component comparisons.
1043 -- Given an arbitrary type, determine whether it contains at least one
1044 -- volatile component.
1047 -- Subp is a subprogram marked with pragma Implemented. Return the specific
1048 -- implementation requirement which the pragma imposes. The return value is
1049 -- either Name_By_Any, Name_By_Entry or Name_By_Protected_Procedure.
1051 function Implements_Interface
1055 -- Returns true if the Typ_Ent implements interface Iface_Ent
1058 -- Determine whether an arbitrary node appears in a pragma that acts as an
1059 -- assertion expression. See Sem_Prag for the list of qualifying pragmas.
1062 -- Returns True if the current scope is within a generic instance
1065 -- Returns True if current scope is within the body of an instance, where
1066 -- several semantic checks (e.g. accessibility checks) are relaxed.
1069 -- Returns True if current scope is with the private part or the body of
1070 -- an instance. Other semantic checks are suppressed in this context.
1073 -- Returns True if current scope is within the visible part of a package
1074 -- instance, where several additional semantic checks apply.
1077 -- Returns True if current scope is within a package body
1080 -- Returns True if node N belongs to a parameter specification
1083 -- Returns true if the expression N occurs within a pragma with name Nam
1086 -- Returns True if N denotes a component or subcomponent in a record or
1087 -- array that has Reverse_Storage_Order.
1090 -- Determines if the current scope is within a subprogram compilation unit
1091 -- (inside a subprogram declaration, subprogram body, or generic subprogram
1092 -- declaration) or within a task or protected body. The test is for
1093 -- appearing anywhere within such a construct (that is it does not need
1094 -- to be directly within).
1097 -- Determine whether a declaration occurs within the visible part of a
1098 -- package specification. The package must be on the scope stack, and the
1099 -- corresponding private part must not.
1102 -- Given the entity of a constant or a type, retrieve the incomplete or
1103 -- partial view of the same entity. Note that Id may not have a partial
1104 -- view in which case the function returns Empty.
1107 -- Inherit the default initial condition procedure from the parent type of
1108 -- derived type Typ.
1111 -- Inherit the rep item chain of type From_Typ without clobbering any
1112 -- existing rep items on Typ's chain. Typ is the destination type.
1114 procedure Inherit_Subprogram_Contract
1117 -- Inherit relevant contract items from source subprogram From_Subp. Subp
1118 -- denotes the destination subprogram. The inherited items are:
1119 -- Extensions_Visible
1120 -- ??? it would be nice if this routine handles Pre'Class and Post'Class
1123 -- In a context that requires a composite or subprogram type and where a
1124 -- prefix is an access type, rewrite the access type node N (which is the
1125 -- prefix, e.g. of an indexed component) as an explicit dereference.
1128 -- Examine all deferred constants in the declaration list Decls and check
1129 -- whether they have been completed by a full constant declaration or an
1130 -- Import pragma. Emit the error message if that is not the case.
1133 -- Install both the generic formal parameters and the formal parameters of
1134 -- generic subprogram Subp_Id into visibility.
1137 -- Determines if N is an actual parameter of out mode in a subprogram call
1140 -- Determines if N is an actual parameter in a subprogram call
1143 -- Determines if N is an actual parameter of a formal of tagged type in a
1144 -- subprogram call.
1147 -- Determine if Obj is an aliased view, i.e. the name of an object to which
1148 -- 'Access or 'Unchecked_Access can apply. Note that this routine uses the
1149 -- rules of the language, it does not take into account the restriction
1150 -- No_Implicit_Aliasing, so it can return True if the restriction is active
1151 -- and Obj violates the restriction. The caller is responsible for calling
1152 -- Restrict.Check_No_Implicit_Aliasing if True is returned, but there is a
1153 -- requirement for obeying the restriction in the call context.
1155 function Is_Ancestor_Package
1158 -- Determine whether package E1 is an ancestor of E2
1161 -- Determines if the given node denotes an atomic object in the sense of
1162 -- the legality checks described in RM C.6(12).
1165 -- Determine whether node N denotes attribute 'Result
1168 -- Determine whether node N denotes a body or a package declaration
1171 -- True if T is a bounded string type. Used to make sure "=" composes
1172 -- properly for bounded string types.
1175 -- Exp is the expression for an array bound. Determines whether the
1176 -- bound is a compile-time known value, or a constant entity, or an
1177 -- enumeration literal, or an expression composed of constant-bound
1178 -- subexpressions which are evaluated by means of standard operators.
1181 -- This routine recognizes expressions that denote an element of one of
1182 -- the predefined containers, when the source only contains an indexing
1183 -- operation and an implicit dereference is inserted by the compiler.
1184 -- In the absence of this optimization, the indexing creates a temporary
1185 -- controlled cursor that sets the tampering bit of the container, and
1186 -- restricts the use of the convenient notation C (X) to contexts that
1187 -- do not check the tampering bit (e.g. C.Include (X, C (Y)). Exp is an
1188 -- explicit dereference. The transformation applies when it has the form
1189 -- F (X).Discr.all.
1191 function Is_Controlling_Limited_Procedure
1193 -- Ada 2005 (AI-345): Determine whether Proc_Nam is a primitive procedure
1194 -- of a limited interface with a controlling first parameter.
1197 -- Returns True if N is a call to a CPP constructor
1199 function Is_Child_Or_Sibling
1202 -- Determine the following relations between two arbitrary packages:
1203 -- 1) One package is the parent of a child package
1204 -- 2) Both packages are siblings and share a common parent
1207 -- First determine whether type T is an interface and then check whether
1208 -- it is of protected, synchronized or task kind.
1211 -- Determine whether arbitrary node N denotes a declaration
1214 -- Returns true if type T represents a delegate. A Delegate is the CIL
1215 -- object used to represent access-to-subprogram types. This is only
1216 -- relevant to CIL, will always return false for other targets.
1218 function Is_Dependent_Component_Of_Mutable_Object
1220 -- Returns True if Object is the name of a subcomponent that depends on
1221 -- discriminants of a variable whose nominal subtype is unconstrained and
1222 -- not indefinite, and the variable is not aliased. Otherwise returns
1223 -- False. The nodes passed to this function are assumed to denote objects.
1226 -- N is a subexpression node of an access type. This function returns true
1227 -- if N appears as the prefix of a node that does a dereference of the
1228 -- access value (selected/indexed component, explicit dereference or a
1229 -- slice), and false otherwise.
1232 -- Returns True if type T1 is a descendent of type T2, and false otherwise.
1233 -- This is the RM definition, a type is a descendent of another type if it
1234 -- is the same type or is derived from a descendent of the other type.
1237 -- The SPARK property "effectively volatile" applies to both types and
1238 -- objects. To qualify as such, an entity must be either volatile or be
1239 -- (of) an array type subject to aspect Volatile_Components.
1242 -- Determine whether an arbitrary node denotes an effectively volatile
1243 -- object.
1246 -- Predicate to determine whether a scope entity comes from a rewritten
1247 -- expression function call, and should be inlined unconditionally. Also
1248 -- used to determine that such a call does not constitute a freeze point.
1251 -- Determine whether node N denotes a reference to a formal parameter of
1252 -- a specific tagged type whose related subprogram is subject to pragma
1253 -- Extensions_Visible with value "False". Several other constructs fall
1254 -- under this category:
1255 -- 1) A qualified expression whose operand is EVF
1256 -- 2) A type conversion whose operand is EVF
1257 -- 3) An if expression with at least one EVF dependent_expression
1258 -- 4) A case expression with at least one EVF dependent_expression
1262 -- The argument is a Uint value which is the Boolean'Pos value of a Boolean
1263 -- operand (i.e. is either 0 for False, or 1 for True). This function tests
1264 -- if it is False (i.e. zero).
1267 -- Returns True iff the number U is a model number of the fixed-point type
1268 -- T, i.e. if it is an exact multiple of Small.
1271 -- Typ is a type entity. This function returns true if this type is fully
1272 -- initialized, meaning that an object of the type is fully initialized.
1273 -- Note that initialization resulting from use of pragma Normalized_Scalars
1274 -- does not count. Note that this is only used for the purpose of issuing
1275 -- warnings for objects that are potentially referenced uninitialized. This
1276 -- means that the result returned is not crucial, but should err on the
1277 -- side of thinking things are fully initialized if it does not know.
1280 -- E is a subprogram. Return True is E is an implicit operation inherited
1281 -- by a derived type declaration.
1283 function Is_Inherited_Operation_For_Type
1286 -- E is a subprogram. Return True is E is an implicit operation inherited
1287 -- by the derived type declaration for type Typ.
1290 -- AI05-0139-2: Check whether Typ is one of the predefined interfaces in
1291 -- Ada.Iterator_Interfaces, or it is derived from one.
1295 -- Returns Yes if N is definitely used as Name in an assignment statement.
1296 -- Returns No if N is definitely NOT used as a Name in an assignment
1297 -- statement. Returns Unknown if we can't tell at this stage (happens in
1298 -- the case where we don't know the type of N yet, and we have something
1299 -- like N.A := 3, where this counts as N being used on the left side of
1300 -- an assignment only if N is not an access type. If it is an access type
1301 -- then it is N.all.A that is assigned, not N.
1304 -- A library-level declaration is one that is accessible from Standard,
1305 -- i.e. a library unit or an entity declared in a library package.
1308 -- Determine whether a given type is a limited class-wide type, in which
1309 -- case it needs a Master_Id, because extensions of its designated type
1310 -- may include task components. A class-wide type that comes from a
1311 -- limited view must be treated in the same way.
1314 -- Determines whether Expr is a reference to a variable or IN OUT mode
1315 -- parameter of the current enclosing subprogram.
1316 -- Why are OUT parameters not considered here ???
1319 -- Determines if the tree referenced by N represents an object. Both
1320 -- variable and constant objects return True (compare Is_Variable).
1323 -- Used to test if AV is an acceptable formal for an OUT or IN OUT formal.
1324 -- Note that the Is_Variable function is not quite the right test because
1325 -- this is a case in which conversions whose expression is a variable (in
1326 -- the Is_Variable sense) with an untagged type target are considered view
1327 -- conversions and hence variables.
1329 function Is_Partially_Initialized_Type
1332 -- Typ is a type entity. This function returns true if this type is partly
1333 -- initialized, meaning that an object of the type is at least partly
1334 -- initialized (in particular in the record case, that at least one
1335 -- component has an initialization expression). Note that initialization
1336 -- resulting from the use of pragma Normalized_Scalars does not count.
1337 -- Include_Implicit controls whether implicit initialization of access
1338 -- values to null, and of discriminant values, is counted as making the
1339 -- type be partially initialized. For the default setting of True, these
1340 -- implicit cases do count, and discriminated types or types containing
1341 -- access values not explicitly initialized will return True. Otherwise
1342 -- if Include_Implicit is False, these cases do not count as making the
1343 -- type be partially initialized.
1346 -- Predicate to implement definition given in RM 6.1.1 (20/3)
1349 -- Determines if type T is a potentially persistent type. A potentially
1350 -- persistent type is defined (recursively) as a scalar type, an untagged
1351 -- record whose components are all of a potentially persistent type, or an
1352 -- array with all static constraints whose component type is potentially
1353 -- persistent. A private type is potentially persistent if the full type
1354 -- is potentially persistent.
1357 -- Return True if node N denotes a protected type name which represents
1358 -- the current instance of a protected object according to RM 9.4(21/2).
1361 -- Return True if a compilation unit is the specification or the
1362 -- body of a remote call interface package.
1365 -- Return True if E is a remote access-to-class-wide type
1368 -- Return True if E is a remote access to subprogram type
1371 -- Return True if N denotes a potentially remote call
1374 -- Return True if Proc_Nam is a procedure renaming of an entry
1377 -- AI05-0139-2: Check whether Typ is derived from the predefined interface
1378 -- Ada.Iterator_Interfaces.Reversible_Iterator.
1381 -- Given an N_Identifier node N, determines if it is a Selector_Name.
1382 -- As described in Sinfo, Selector_Names are special because they
1383 -- represent use of the N_Identifier node for a true identifier, when
1384 -- normally such nodes represent a direct name.
1387 -- Determines if the tree referenced by N represents an initialization
1388 -- expression in SPARK 2005, suitable for initializing an object in an
1389 -- object declaration.
1392 -- Determines if the tree referenced by N represents an object in SPARK
1393 -- 2005. This differs from Is_Object_Reference in that only variables,
1394 -- constants, formal parameters, and selected_components of those are
1395 -- valid objects in SPARK 2005.
1398 -- Determine whether an arbitrary [private] type is specifically tagged
1402 -- Check if the node N is a statement node. Note that this includes
1403 -- the case of procedure call statements (unlike the direct use of
1404 -- the N_Statement_Other_Than_Procedure_Call subtype from Sinfo).
1405 -- Note that a label is *not* a statement, and will return False.
1407 function Is_Subprogram_Stub_Without_Prior_Declaration
1409 -- Return True if N is a subprogram stub with no prior subprogram
1410 -- declaration.
1413 -- Returns True if E is a synchronized tagged type (AARM 3.9.4 (6/2))
1416 -- Returns True if the node N is a statement which is known to cause an
1417 -- unconditional transfer of control at runtime, i.e. the following
1418 -- statement definitely will not be executed.
1422 -- The argument is a Uint value which is the Boolean'Pos value of a Boolean
1423 -- operand (i.e. is either 0 for False, or 1 for True). This function tests
1424 -- if it is True (i.e. non-zero).
1427 -- Determine whether an arbitrary entity denotes an instance of function
1428 -- Ada.Unchecked_Conversion.
1432 -- True if T is Universal_Integer or Universal_Real
1435 -- Returns true if type T represents a value type. This is only relevant to
1436 -- CIL, will always return false for other targets. A value type is a CIL
1437 -- object that is accessed directly, as opposed to the other CIL objects
1438 -- that are accessed through managed pointers.
1441 -- Returns true if E has variable size components
1444 -- Returns true if E has variable size components
1446 function Is_Variable
1449 -- Determines if the tree referenced by N represents a variable, i.e. can
1450 -- appear on the left side of an assignment. There is one situation (formal
1451 -- parameters) in which untagged type conversions are also considered
1452 -- variables, but Is_Variable returns False for such cases, since it has
1453 -- no knowledge of the context. Note that this is the point at which
1454 -- Assignment_OK is checked, and True is returned for any tree thus marked.
1455 -- Use_Original_Node is used to perform the test on Original_Node (N). By
1456 -- default is True since this routine is commonly invoked as part of the
1457 -- semantic analysis and it must not be disturbed by the rewriten nodes.
1460 -- Check whether T is derived from a visibly controlled type. This is true
1461 -- if the root type is declared in Ada.Finalization. If T is derived
1462 -- instead from a private type whose full view is controlled, an explicit
1463 -- Initialize/Adjust/Finalize subprogram does not override the inherited
1464 -- one.
1467 -- Determines if the given node denotes an volatile object in the sense of
1468 -- the legality checks described in RM C.6(12). Note that the test here is
1469 -- for something actually declared as volatile, not for an object that gets
1470 -- treated as volatile (see Einfo.Treat_As_Volatile).
1473 -- Applies to Itypes. True if the Itype is attached to a declaration for
1474 -- the type through its Parent field, which may or not be present in the
1475 -- tree.
1478 -- This procedure is called to clear all constant indications from all
1479 -- entities in the current scope and in any parent scopes if the current
1480 -- scope is a block or a package (and that recursion continues to the top
1481 -- scope that is not a block or a package). This is used when the
1482 -- sequential flow-of-control assumption is violated (occurrence of a
1483 -- label, head of a loop, or start of an exception handler). The effect of
1484 -- the call is to clear the Current_Value field (but we do not need to
1485 -- clear the Is_True_Constant flag, since that only gets reset if there
1486 -- really is an assignment somewhere in the entity scope). This procedure
1487 -- also calls Kill_All_Checks, since this is a special case of needing to
1488 -- forget saved values. This procedure also clears the Is_Known_Null and
1489 -- Is_Known_Non_Null and Is_Known_Valid flags in variables, constants or
1490 -- parameters since these are also not known to be trustable any more.
1491 --
1492 -- The Last_Assignment_Only flag is set True to clear only Last_Assignment
1493 -- fields and leave other fields unchanged. This is used when we encounter
1494 -- an unconditional flow of control change (return, goto, raise). In such
1495 -- cases we don't need to clear the current values, since it may be that
1496 -- the flow of control change occurs in a conditional context, and if it
1497 -- is not taken, then it is just fine to keep the current values. But the
1498 -- Last_Assignment field is different, if we have a sequence assign-to-v,
1499 -- conditional-return, assign-to-v, we do not want to complain that the
1500 -- second assignment clobbers the first.
1502 procedure Kill_Current_Values
1505 -- This performs the same processing as described above for the form with
1506 -- no argument, but for the specific entity given. The call has no effect
1507 -- if the entity Ent is not for an object. Last_Assignment_Only has the
1508 -- same meaning as for the call with no Ent.
1511 -- Called when an address clause or pragma Import is applied to an entity.
1512 -- If the entity is a variable or a constant, and size check code is
1513 -- present, this size check code is killed, since the object will not be
1514 -- allocated by the program.
1517 -- The node N is an entity reference. This function determines whether the
1518 -- reference is for sure an assignment of the entity, returning True if
1519 -- so. This differs from May_Be_Lvalue in that it defaults in the other
1520 -- direction. Cases which may possibly be assignments but are not known to
1521 -- be may return True from May_Be_Lvalue, but False from this function.
1524 -- HSS is a handled statement sequence. This function returns the last
1525 -- statement in Statements (HSS) that has Comes_From_Source set. If no
1526 -- such statement exists, Empty is returned.
1528 function Matching_Static_Array_Bounds
1531 -- L_Typ and R_Typ are two array types. Returns True when they have the
1532 -- same number of dimensions, and the same static bounds for each index
1533 -- position.
1536 -- Given a node which designates the context of analysis and an origin in
1537 -- the tree, traverse from Root_Nod and mark all allocators as either
1538 -- dynamic or static depending on Context_Nod. Any incorrect marking is
1539 -- cleaned up during resolution.
1542 -- Determines if N could be an lvalue (e.g. an assignment left hand side).
1543 -- An lvalue is defined as any expression which appears in a context where
1544 -- a name is required by the syntax, and the identity, rather than merely
1545 -- the value of the node is needed (for example, the prefix of an Access
1546 -- attribute is in this category). Note that, as implied by the name, this
1547 -- test is conservative. If it cannot be sure that N is NOT an lvalue, then
1548 -- it returns True. It tries hard to get the answer right, but it is hard
1549 -- to guarantee this in all cases. Note that it is more possible to give
1550 -- correct answer if the tree is fully analyzed.
1553 -- Returns True if a function has defaults for all but its first
1554 -- formal. Used in Ada 2005 mode to solve the syntactic ambiguity that
1555 -- results from an indexing of a function call written in prefix form.
1558 -- Copy recursively an analyzed list of nodes. Uses New_Copy_Tree defined
1559 -- below. As for New_Copy_Tree, it is illegal to attempt to copy extended
1560 -- nodes (entities) either directly or indirectly using this function.
1562 function New_Copy_Tree
1567 -- Given a node that is the root of a subtree, Copy_Tree copies the entire
1568 -- syntactic subtree, including recursively any descendents whose parent
1569 -- field references a copied node (descendents not linked to a copied node
1570 -- by the parent field are not copied, instead the copied tree references
1571 -- the same descendent as the original in this case, which is appropriate
1572 -- for non-syntactic fields such as Etype). The parent pointers in the
1573 -- copy are properly set. Copy_Tree (Empty/Error) returns Empty/Error.
1574 -- The one exception to the rule of not copying semantic fields is that
1575 -- any implicit types attached to the subtree are duplicated, so that
1576 -- the copy contains a distinct set of implicit type entities. Thus this
1577 -- function is used when it is necessary to duplicate an analyzed tree,
1578 -- declared in the same or some other compilation unit. This function is
1579 -- declared here rather than in atree because it uses semantic information
1580 -- in particular concerning the structure of itypes and the generation of
1581 -- public symbols.
1583 -- The Map argument, if set to a non-empty Elist, specifies a set of
1584 -- mappings to be applied to entities in the tree. The map has the form:
1585 --
1586 -- old entity 1
1587 -- new entity to replace references to entity 1
1588 -- old entity 2
1589 -- new entity to replace references to entity 2
1590 -- ...
1591 --
1592 -- The call destroys the contents of Map in this case
1593 --
1594 -- The parameter New_Sloc, if set to a value other than No_Location, is
1595 -- used as the Sloc value for all nodes in the new copy. If New_Sloc is
1596 -- set to its default value No_Location, then the Sloc values of the
1597 -- nodes in the copy are simply copied from the corresponding original.
1598 --
1599 -- The Comes_From_Source indication is unchanged if New_Sloc is set to
1600 -- the default No_Location value, but is reset if New_Sloc is given, since
1601 -- in this case the result clearly is neither a source node or an exact
1602 -- copy of a source node.
1603 --
1604 -- The parameter New_Scope, if set to a value other than Empty, is the
1605 -- value to use as the Scope for any Itypes that are copied. The most
1606 -- typical value for this parameter, if given, is Current_Scope.
1608 function New_External_Entity
1616 -- This function creates an N_Defining_Identifier node for an internal
1617 -- created entity, such as an implicit type or subtype, or a record
1618 -- initialization procedure. The entity name is constructed with a call
1619 -- to New_External_Name (Related_Id, Suffix, Suffix_Index, Prefix), so
1620 -- that the generated name may be referenced as a public entry, and the
1621 -- Is_Public flag is set if needed (using Set_Public_Status). If the
1622 -- entity is for a type or subtype, the size/align fields are initialized
1623 -- to unknown (Uint_0).
1625 function New_Internal_Entity
1630 -- This function is similar to New_External_Entity, except that the
1631 -- name is constructed by New_Internal_Name (Id_Char). This is used
1632 -- when the resulting entity does not have to be referenced as a
1633 -- public entity (and in this case Is_Public is not set).
1637 -- Next_Actual (N) is equivalent to N := Next_Actual (N). Note that we
1638 -- inline this procedural form, but not the functional form that follows.
1641 -- Find next actual parameter in declaration order. As described for
1642 -- First_Actual, this is the next actual in the declaration order, not
1643 -- the call order, so this does not correspond to simply taking the
1644 -- next entry of the Parameter_Associations list. The argument is an
1645 -- actual previously returned by a call to First_Actual or Next_Actual.
1646 -- Note that the result produced is always an expression, not a parameter
1647 -- association node, even if named notation was used.
1649 procedure Normalize_Actuals
1654 -- Reorders lists of actuals according to names of formals, value returned
1655 -- in Success indicates success of reordering. For more details, see body.
1656 -- Errors are reported only if Report is set to True.
1659 -- This routine is called if the sub-expression N maybe the target of
1660 -- an assignment (e.g. it is the left side of an assignment, used as
1661 -- an out parameters, or used as prefixes of access attributes). It
1662 -- sets May_Be_Modified in the associated entity if there is one,
1663 -- taking into account the rule that in the case of renamed objects,
1664 -- it is the flag in the renamed object that must be set.
1665 --
1666 -- The parameter Sure is set True if the modification is sure to occur
1667 -- (e.g. target of assignment, or out parameter), and to False if the
1668 -- modification is only potential (e.g. address of entity taken).
1671 -- Return the accessibility level of the view of the object Obj. For
1672 -- convenience, qualified expressions applied to object names are also
1673 -- allowed as actuals for this function.
1676 -- [Ada 2012: AI05-0125-1]: If S is an inherited dispatching primitive S2,
1677 -- or overrides an inherited dispatching primitive S2, the original
1678 -- corresponding operation of S is the original corresponding operation of
1679 -- S2. Otherwise, it is S itself.
1682 -- Retrieve the name of aspect or pragma N taking into account a possible
1683 -- rewrite and whether the pragma is generated from an aspect as the names
1684 -- may be different. The routine also deals with 'Class in which case it
1685 -- returns the following values:
1686 --
1687 -- Invariant -> Name_uInvariant
1688 -- Post'Class -> Name_uPost
1689 -- Pre'Class -> Name_uPre
1690 -- Type_Invariant -> Name_uType_Invariant
1691 -- Type_Invariant'Class -> Name_uType_Invariant
1694 -- Given a policy, return the policy identifier associated with it. If no
1695 -- such policy is in effect, the value returned is No_Name.
1698 -- Subp is the entity for a subprogram call. This function returns True if
1699 -- predicate tests are required for the arguments in this call (this is the
1700 -- normal case). It returns False for special cases where these predicate
1701 -- tests should be skipped (see body for details).
1704 -- Returns True if the names of both entities correspond with matching
1705 -- primitives. This routine includes support for the case in which one
1706 -- or both entities correspond with entities built by Derive_Subprogram
1707 -- with a special name to avoid being overridden (i.e. return true in case
1708 -- of entities with names "nameP" and "name" or vice versa).
1711 -- Returns some private component (if any) of the given Type_Id.
1712 -- Used to enforce the rules on visibility of operations on composite
1713 -- types, that depend on the full view of the component type. For a
1714 -- record type there may be several such components, we just return
1715 -- the first one.
1717 procedure Process_End_Label
1721 -- N is a node whose End_Label is to be processed, generating all
1722 -- appropriate cross-reference entries, and performing style checks
1723 -- for any identifier references in the end label. Typ is either
1724 -- 'e' or 't indicating the type of the cross-reference entity
1725 -- (e for spec, t for body, see Lib.Xref spec for details). The
1726 -- parameter Ent gives the entity to which the End_Label refers,
1727 -- and to which cross-references are to be generated.
1730 -- Determine whether entity Id is referenced within expression Expr
1733 -- Returns True if the expression Expr contains any references to a
1734 -- generic type. This can only happen within a generic template.
1737 -- Removes E from the homonym chain
1740 -- This is used to construct the second argument in a call to Rep_To_Pos
1741 -- which is Standard_True if range checks are enabled (E is an entity to
1742 -- which the Range_Checks_Suppressed test is applied), and Standard_False
1743 -- if range checks are suppressed. Loc is the location for the node that
1744 -- is returned (which is a New_Occurrence of the appropriate entity).
1745 --
1746 -- Note: one might think that it would be fine to always use True and
1747 -- to ignore the suppress in this case, but it is generally better to
1748 -- believe a request to suppress exceptions if possible, and further
1749 -- more there is at least one case in the generated code (the code for
1750 -- array assignment in a loop) that depends on this suppression.
1753 -- N is a node which should have an entity value if it is an entity name.
1754 -- If not, then check if there were previous errors. If so, just fill
1755 -- in with Any_Id and ignore. Otherwise signal a program error exception.
1756 -- This is used as a defense mechanism against ill-formed trees caused by
1757 -- previous errors (particularly in -gnatq mode).
1759 function Requires_State_Refinement
1762 -- Determine whether a package denoted by its spec and body entities
1763 -- requires refinement of abstract states.
1766 -- Id is a type entity. The result is True when temporaries of this type
1767 -- need to be wrapped in a transient scope to be reclaimed properly when a
1768 -- secondary stack is in use. Examples of types requiring such wrapping are
1769 -- controlled types and variable-sized types including unconstrained
1770 -- arrays.
1773 -- Reset the Analyzed flags in all nodes of the tree whose root is N
1776 -- Set the current SPARK_Mode to whatever Mode denotes. This routime must
1777 -- be used in tandem with Save_SPARK_Mode_And_Set.
1780 -- Return true if Subp is a function that returns an unconstrained type
1783 -- Similar to attribute Root_Type, but this version always follows the
1784 -- Full_View of a private type (if available) while searching for the
1785 -- ultimate derivation ancestor.
1787 function Safe_To_Capture_Value
1791 -- The caller is interested in capturing a value (either the current value,
1792 -- or an indication that the value is non-null) for the given entity Ent.
1793 -- This value can only be captured if sequential execution semantics can be
1794 -- properly guaranteed so that a subsequent reference will indeed be sure
1795 -- that this current value indication is correct. The node N is the
1796 -- construct which resulted in the possible capture of the value (this
1797 -- is used to check if we are in a conditional).
1798 --
1799 -- Cond is used to skip the test for being inside a conditional. It is used
1800 -- in the case of capturing values from if/while tests, which already do a
1801 -- proper job of handling scoping issues without this help.
1802 --
1803 -- The only entities whose values can be captured are OUT and IN OUT formal
1804 -- parameters, and variables unless Cond is True, in which case we also
1805 -- allow IN formals, loop parameters and constants, where we cannot ever
1806 -- capture actual value information, but we can capture conditional tests.
1809 -- Determine if two (possibly expanded) names are the same name. This is
1810 -- a purely syntactic test, and N1 and N2 need not be analyzed.
1813 -- Determine if Node1 and Node2 are known to designate the same object.
1814 -- This is a semantic test and both nodes must be fully analyzed. A result
1815 -- of True is decisively correct. A result of False does not necessarily
1816 -- mean that different objects are designated, just that this could not
1817 -- be reliably determined at compile time.
1820 -- Determines if T1 and T2 represent exactly the same type. Two types
1821 -- are the same if they are identical, or if one is an unconstrained
1822 -- subtype of the other, or they are both common subtypes of the same
1823 -- type with identical constraints. The result returned is conservative.
1824 -- It is True if the types are known to be the same, but a result of
1825 -- False is indecisive (e.g. the compiler may not be able to tell that
1826 -- two constraints are identical).
1829 -- Determines if Node1 and Node2 are known to be the same value, which is
1830 -- true if they are both compile time known values and have the same value,
1831 -- or if they are the same object (in the sense of function Same_Object).
1832 -- A result of False does not necessarily mean they have different values,
1833 -- just that it is not possible to determine they have the same value.
1835 procedure Save_SPARK_Mode_And_Set
1838 -- Save the current SPARK_Mode in effect in Mode. Establish the SPARK_Mode
1839 -- (if any) of a package or a subprogram denoted by Context. This routine
1840 -- must be used in tandem with Restore_SPARK_Mode.
1843 -- Tests if type T can be determined at compile time to have at least one
1844 -- scalar part in the sense of the Valid_Scalars attribute. Returns True if
1845 -- this is the case, and False if no scalar parts are present (meaning that
1846 -- the result of Valid_Scalars applied to T is always vacuously True).
1849 -- Determines if the entity Scope1 is the same as Scope2, or if it is
1850 -- inside it, where both entities represent scopes. Note that scopes
1851 -- are only partially ordered, so Scope_Within_Or_Same (A,B) and
1852 -- Scope_Within_Or_Same (B,A) can both be False for a given pair A,B.
1855 -- Like Scope_Within_Or_Same, except that this function returns
1856 -- False in the case where Scope1 and Scope2 are the same scope.
1859 -- Same as Basic_Set_Convention, but with an extra check for access types.
1860 -- In particular, if E is an access-to-subprogram type, and Val is a
1861 -- foreign convention, then we set Can_Use_Internal_Rep to False on E.
1862 -- Also, if the Etype of E is set and is an anonymous access type with
1863 -- no convention set, this anonymous type inherits the convention of E.
1867 -- Establish the entity E as the currently visible definition of its
1868 -- associated name (i.e. the Node_Id associated with its name).
1871 -- Sets the Debug_Info_Needed flag on entity T , and also on any entities
1872 -- that are needed by T (for an object, the type of the object is needed,
1873 -- and for a type, various subsidiary types are needed -- see body for
1874 -- details). Never has any effect on T if the Debug_Info_Off flag is set.
1875 -- This routine should always be used instead of Set_Needs_Debug_Info to
1876 -- ensure that subsidiary entities are properly handled.
1879 -- This procedure has the same calling sequence as Set_Entity, but it
1880 -- performs additional checks as follows:
1881 --
1882 -- If Style_Check is set, then it calls a style checking routine which
1883 -- can check identifier spelling style. This procedure also takes care
1884 -- of checking the restriction No_Implementation_Identifiers.
1885 --
1886 -- If restriction No_Abort_Statements is set, then it checks that the
1887 -- entity is not Ada.Task_Identification.Abort_Task.
1888 --
1889 -- If restriction No_Dynamic_Attachment is set, then it checks that the
1890 -- entity is not one of the restricted names for this restriction.
1891 --
1892 -- If restriction No_Long_Long_Integers is set, then it checks that the
1893 -- entity is not Standard.Long_Long_Integer.
1894 --
1895 -- If restriction No_Implementation_Identifiers is set, then it checks
1896 -- that the entity is not implementation defined.
1900 -- Sets the Entity_Id value associated with the given name, which is the
1901 -- Id of the innermost visible entity with the given name. See the body
1902 -- of package Sem_Ch8 for further details on the handling of visibility.
1905 -- The arguments may be parameter associations, whose descendants
1906 -- are the optional formal name and the actual parameter. Positional
1907 -- parameters are already members of a list, and do not need to be
1908 -- chained separately. See also First_Actual and Next_Actual.
1912 -- Sets Optimize_Alignment_Space/Time flags in E from current settings
1915 -- If an entity (visible or otherwise) is defined in a library
1916 -- package, or a package that is itself public, then this subprogram
1917 -- labels the entity public as well.
1920 -- N is the node for either a left hand side (Out_Param set to False),
1921 -- or an Out or In_Out parameter (Out_Param set to True). If there is
1922 -- an assignable entity being referenced, then the appropriate flag
1923 -- (Referenced_As_LHS if Out_Param is False, Referenced_As_Out_Parameter
1924 -- if Out_Param is True) is set True, and the other flag set False.
1927 -- Set the flag Is_Transient of the current scope
1931 -- Copies the Esize field and Has_Biased_Representation flag from sub(type)
1932 -- entity T2 to (sub)type entity T1. Also copies the Is_Unsigned_Type flag
1933 -- in the fixed-point and discrete cases, and also copies the alignment
1934 -- value from T2 to T1. It does NOT copy the RM_Size field, which must be
1935 -- separately set if this is required to be copied also.
1938 -- True if the current scope is transient
1941 -- This function analyzes the given expression node and then resolves it
1942 -- as Standard.Boolean. If the result is static, then Uint_1 or Uint_0 is
1943 -- returned corresponding to the value, otherwise an error message is
1944 -- output and No_Uint is returned.
1947 -- This function analyzes the given expression node and then resolves it
1948 -- as any integer type. If the result is static, then the value of the
1949 -- universal expression is returned, otherwise an error message is output
1950 -- and a value of No_Uint is returned.
1953 -- Return True if it can be statically determined that the Expressions
1954 -- E1 and E2 refer to different objects
1957 -- Determine whether node N is a loop statement subject to at least one
1958 -- 'Loop_Entry attribute.
1961 -- Return the accessibility level of the view denoted by Subp
1964 -- Return True if Typ supports the GCC built-in atomic operations (i.e. if
1965 -- Typ is properly sized and aligned).
1968 -- Print debugging information on entry to each unit being analyzed
1971 -- Move a list of entities from one scope to another, and recompute
1972 -- Is_Public based upon the new scope.
1975 -- Return the accessibility level of Typ
1977 function Type_Without_Stream_Operation
1980 -- AI05-0161: In Ada 2012, if the restriction No_Default_Stream_Attributes
1981 -- is active then we cannot generate stream subprograms for composite types
1982 -- with elementary subcomponents that lack user-defined stream subprograms.
1983 -- This predicate determines whether a type has such an elementary
1984 -- subcomponent. If Op is TSS_Null, a type that lacks either Read or Write
1985 -- prevents the construction of a composite stream operation. If Op is
1986 -- specified we check only for the given stream operation.
1989 -- Return the entity which represents declaration N, so that different
1990 -- views of the same entity have the same unique defining entity:
1991 -- * package spec and body;
1992 -- * subprogram declaration, subprogram stub and subprogram body;
1993 -- * private view and full view of a type;
1994 -- * private view and full view of a deferred constant.
1995 -- In other cases, return the defining entity for N.
1998 -- Return the unique entity for entity E, which would be returned by
1999 -- Unique_Defining_Entity if applied to the enclosing declaration of E.
2002 -- Return a unique name for entity E, which could be used to identify E
2003 -- across compilation units.
2006 -- Determine whether a compilation unit is visible in the current context,
2007 -- because there is a with_clause that makes the unit available. Used to
2008 -- provide better messages on common visiblity errors on operators.
2011 -- Yields Universal_Integer or Universal_Real if this is a candidate
2015 -- Removes any qualifications from Expr. For example, for T1'(T2'(X)), this
2016 -- returns X. If Expr is not a qualified expression, returns Expr.
2019 -- [Ada 2012:AI-0125-1]: Collect all the visible parents and progenitors
2020 -- of a type extension or private extension declaration. If the full-view
2021 -- of private parents and progenitors is available then it is used to
2022 -- generate the list of visible ancestors; otherwise their partial
2023 -- view is added to the resulting list.
2026 -- Determines if Current_Scope is within an init proc
2029 -- Returns True if entity Id is declared within scope S
2032 -- Output error message for incorrectly typed expression. Expr is the node
2033 -- for the incorrectly typed construct (Etype (Expr) is the type found),
2034 -- and Expected_Type is the entity for the expected type. Note that Expr
2035 -- does not have to be a subexpression, anything with an Etype field may
2036 -- be used.