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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S E M _ R E S --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2020, 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 ------------------------------------------------------------------------------
88 -----------------------
89 -- Local Subprograms --
90 -----------------------
92 -- Second pass (top-down) type checking and overload resolution procedures
93 -- Typ is the type required by context. These procedures propagate the
94 -- type information recursively to the descendants of N. If the node is not
95 -- overloaded, its Etype is established in the first pass. If overloaded,
96 -- the Resolve routines set the correct type. For arithmetic operators, the
97 -- Etype is the base type of the context.
99 -- Note that Resolve_Attribute is separated off in Sem_Attr
102 -- Enforce the restrictions on the use of discriminants when constraining
103 -- a component of a discriminated type (record or concurrent type).
106 -- Given a node for an operator associated with type T, check that the
107 -- operator is visible. Operators all of whose operands are universal must
108 -- be checked for visibility during resolution because their type is not
109 -- determinable based on their operands.
111 procedure Check_Fully_Declared_Prefix
114 -- Check that the type of the prefix of a dereference is not incomplete
117 -- Given a call node, Call, which is known to occur immediately within the
118 -- subprogram being called, determines whether it is a detectable case of
119 -- an infinite recursion, and if so, outputs appropriate messages. Returns
120 -- True if an infinite recursion is detected, and False otherwise.
123 -- N is the node for a logical operator. If the operator is predefined, and
124 -- the root type of the operands is Standard.Boolean, then a check is made
125 -- for restriction No_Direct_Boolean_Operators. This procedure also handles
126 -- the style check for Style_Check_Boolean_And_Or.
129 -- N is either an indexed component or a selected component. This function
130 -- returns true if the prefix refers to an object that has an address
131 -- clause (the case in which we may want to issue a warning).
134 -- Determine whether E is an access type declared by an access declaration,
135 -- and not an (anonymous) allocator type.
138 -- Utility to check whether the entity for an operator is a predefined
139 -- operator, in which case the expression is left as an operator in the
140 -- tree (else it is rewritten into a call). An instance of an intrinsic
141 -- conversion operation may be given an operator name, but is not treated
142 -- like an operator. Note that an operator that is an imported back-end
143 -- builtin has convention Intrinsic, but is expected to be rewritten into
144 -- a call, so such an operator is not treated as predefined by this
145 -- predicate.
147 procedure Preanalyze_And_Resolve
151 -- Subsidiary of public versions of Preanalyze_And_Resolve.
154 -- If a default expression in entry call N depends on the discriminants
155 -- of the task, it must be replaced with a reference to the discriminant
156 -- of the task being called.
158 procedure Resolve_Op_Concat_Arg
163 -- Internal procedure for Resolve_Op_Concat to resolve one operand of
164 -- concatenation operator. The operand is either of the array type or of
165 -- the component type. If the operand is an aggregate, and the component
166 -- type is composite, this is ambiguous if component type has aggregates.
169 -- Does the first part of the work of Resolve_Op_Concat
172 -- Does the "rest" of the work of Resolve_Op_Concat, after the left operand
173 -- has been resolved. See Resolve_Op_Concat for details.
213 function Operator_Kind
216 -- Utility to map the name of an operator into the corresponding Node. Used
217 -- by other node rewriting procedures.
220 -- Resolve actuals of call, and add default expressions for missing ones.
221 -- N is the Node_Id for the subprogram call, and Nam is the entity of the
222 -- called subprogram.
225 -- Called from Resolve_Call, when the prefix denotes an entry or element
226 -- of entry family. Actuals are resolved as for subprograms, and the node
227 -- is rebuilt as an entry call. Also called for protected operations. Typ
228 -- is the context type, which is used when the operation is a protected
229 -- function with no arguments, and the return value is indexed.
232 -- Called when P is the prefix of an indexed component, or of a selected
233 -- component, or of a slice. If P is of an access type, we unconditionally
234 -- rewrite it as an explicit dereference. This ensures that the expander
235 -- and the code generator have a fully explicit tree to work with.
238 -- A call to a user-defined intrinsic operator is rewritten as a call to
239 -- the corresponding predefined operator, with suitable conversions. Note
240 -- that this applies only for intrinsic operators that denote predefined
241 -- operators, not ones that are intrinsic imports of back-end builtins.
244 -- Ditto, for arithmetic unary operators
247 -- If an operator node resolves to a call to a user-defined operator,
248 -- rewrite the node as a function call.
250 procedure Make_Call_Into_Operator
254 -- Inverse transformation: if an operator is given in functional notation,
255 -- then after resolving the node, transform into an operator node, so that
256 -- operands are resolved properly. Recall that predefined operators do not
257 -- have a full signature and special resolution rules apply.
259 procedure Rewrite_Renamed_Operator
263 -- An operator can rename another, e.g. in an instantiation. In that
264 -- case, the proper operator node must be constructed and resolved.
267 -- The String_Literal_Subtype is built for all strings that are not
268 -- operands of a static concatenation operation. If the argument is not
269 -- a N_String_Literal node, then the call has no effect.
272 -- Build subtype of array type, with the range specified by the slice
275 -- Called after N has been resolved and evaluated, but before range checks
276 -- have been applied. This rewrites the conversion into a simpler form.
279 -- A universal_fixed expression in an universal context is unambiguous if
280 -- there is only one applicable fixed point type. Determining whether there
281 -- is only one requires a search over all visible entities, and happens
282 -- only in very pathological cases (see 6115-006).
284 -------------------------
285 -- Ambiguous_Character --
286 -------------------------
291 begin
295 -- First the ones in Standard
300 -- Include Wide_Wide_Character in Ada 2005 mode
306 -- Now any other types that match
316 -------------------------
317 -- Analyze_And_Resolve --
318 -------------------------
321 begin
327 begin
332 -- Versions with check(s) suppressed
334 procedure Analyze_And_Resolve
338 is
341 begin
343 declare
345 begin
351 else
352 declare
354 begin
362 and then Scope_Is_Transient
363 then
364 -- This can only happen if a transient scope was created for an inner
365 -- expression, which will be removed upon completion of the analysis
366 -- of an enclosing construct. The transient scope must have the
367 -- suppress status of the enclosing environment, not of this Analyze
368 -- call.
371 Scope_Suppress;
375 procedure Analyze_And_Resolve
378 is
381 begin
383 declare
385 begin
391 else
392 declare
394 begin
403 Scope_Suppress;
407 ----------------------------
408 -- Check_Discriminant_Use --
409 ----------------------------
417 begin
418 -- Any use in a spec-expression is legal
425 -- Discriminant cannot be used to constrain a scalar type
432 then
437 -- The following check catches the unusual case where a
438 -- discriminant appears within an index constraint that is part
439 -- of a larger expression within a constraint on a component,
440 -- e.g. "C : Int range 1 .. F (new A(1 .. D))". For now we only
441 -- check case of record components, and note that a similar check
442 -- should also apply in the case of discriminant constraints
443 -- below. ???
445 -- Note that the check for N_Subtype_Declaration below is to
446 -- detect the valid use of discriminants in the constraints of a
447 -- subtype declaration when this subtype declaration appears
448 -- inside the scope of a record type (which is syntactically
449 -- illegal, but which may be created as part of derived type
450 -- processing for records). See Sem_Ch3.Build_Derived_Record_Type
451 -- for more info.
455 and then not
457 and then
459 | N_Subtype_Declaration
461 then
462 Error_Msg_N
467 -- Detect a common error:
469 -- type R (D : Positive := 100) is record
470 -- Name : String (1 .. D);
471 -- end record;
473 -- The default value causes an object of type R to be allocated
474 -- with room for Positive'Last characters. The RM does not mandate
475 -- the allocation of the maximum size, but that is what GNAT does
476 -- so we should warn the programmer that there is a problem.
485 -- Return True if type T has a large enough range that any
486 -- array whose index type covered the whole range of the type
487 -- would likely raise Storage_Error.
489 ------------------------
490 -- Large_Storage_Type --
491 ------------------------
494 begin
495 -- The type is considered large if its bounds are known at
496 -- compile time and if it requires at least as many bits as
497 -- a Positive to store the possible values.
501 and then
506 -- Start of processing for Check_Large
508 begin
509 -- Check that the Disc has a large range
515 -- If the enclosing type is limited, we allocate only the
516 -- default value, not the maximum, and there is no need for
517 -- a warning.
523 -- Check that it is the high bound
527 then
531 -- Check the array allows a large range at this bound. First
532 -- find the array
546 -- Next, find the dimension
554 loop
563 -- Now, check the dimension has a large range
569 -- Warn about the danger
571 Error_Msg_N
581 -- Legal case is in index or discriminant constraint
584 | N_Discriminant_Association
585 then
587 Error_Msg_N
592 then
593 Error_Msg_N
599 -- Otherwise, context is an expression. It should not be within (i.e. a
600 -- subexpression of) a constraint for a component.
602 else
606 N_Component_Declaration | N_Subtype_Indication | N_Entry_Declaration
607 loop
613 -- If the discriminant is used in an expression that is a bound of a
614 -- scalar type, an Itype is created and the bounds are attached to
615 -- its range, not to the original subtype indication. Such use is of
616 -- course a double fault.
620 | N_Derived_Type_Definition
623 -- The constraint itself may be given by a subtype indication,
624 -- rather than by a more common discrete range.
627 and then
631 then
632 Error_Msg_N
638 --------------------------------
639 -- Check_For_Visible_Operator --
640 --------------------------------
643 begin
645 Error_Msg_NE -- CODEFIX
647 Error_Msg_N -- CODEFIX
652 ----------------------------------
653 -- Check_Fully_Declared_Prefix --
654 ----------------------------------
656 procedure Check_Fully_Declared_Prefix
659 is
660 begin
661 -- Check that the designated type of the prefix of a dereference is
662 -- not an incomplete type. This cannot be done unconditionally, because
663 -- dereferences of private types are legal in default expressions. This
664 -- case is taken care of in Check_Fully_Declared, called below. There
665 -- are also 2005 cases where it is legal for the prefix to be unfrozen.
667 -- This consideration also applies to similar checks for allocators,
668 -- qualified expressions, and type conversions.
670 -- An additional exception concerns other per-object expressions that
671 -- are not directly related to component declarations, in particular
672 -- representation pragmas for tasks. These will be per-object
673 -- expressions if they depend on discriminants or some global entity.
674 -- If the task has access discriminants, the designated type may be
675 -- incomplete at the point the expression is resolved. This resolution
676 -- takes place within the body of the initialization procedure, where
677 -- the discriminant is replaced by its discriminal.
681 then
684 -- Ada 2005 (AI-326): Tagged incomplete types allowed. The wrong usages
685 -- are handled by Analyze_Access_Attribute, Analyze_Assignment,
686 -- Analyze_Object_Renaming, and Freeze_Entity.
692 E_Incomplete_Type
694 then
696 else
701 ------------------------------
702 -- Check_Infinite_Recursion --
703 ------------------------------
707 -- Return the nearest enclosing declaration or statement that houses
708 -- arbitrary node N.
711 -- Determine whether call N invokes the related enclosing subprogram
712 -- with actuals that differ from the subprogram's formals.
715 -- Determine whether arbitrary node N denotes a conditional construct
718 -- Determine whether arbitrary node N denotes a control flow statement
719 -- or a construct that may contains such a statement.
722 -- Determine whether arbitrary node N appears immediately within the
723 -- statements of an entry or subprogram body.
726 -- Determine whether arbitrary node N appears immediately within the
727 -- body of an entry or subprogram, and is preceded by a single raise
728 -- statement.
731 -- Determine whether arbitrary node N denotes a raise statement
734 -- Determine whether arbitrary node N is the sole source statement in
735 -- the body of the enclosing subprogram.
738 -- Determine whether arbitrary node N is preceded by a control flow
739 -- statement.
742 -- Determine whether arbitrary node N appears within a conditional
743 -- construct.
745 ----------------------------------------
746 -- Enclosing_Declaration_Or_Statement --
747 ----------------------------------------
749 function Enclosing_Declaration_Or_Statement
751 is
754 begin
760 -- Prevent the search from going too far
772 --------------------------------------
773 -- Invoked_With_Different_Arguments --
774 --------------------------------------
782 begin
783 -- Determine whether the formals of the invoked subprogram are not
784 -- used as actuals in the call.
790 -- The current actual does not match the current formal
794 then
805 ------------------------------
806 -- Is_Conditional_Statement --
807 ------------------------------
810 begin
811 return
813 | N_Case_Expression
814 | N_Case_Statement
815 | N_If_Expression
816 | N_If_Statement
817 | N_Or_Else;
820 -------------------------------
821 -- Is_Control_Flow_Statement --
822 -------------------------------
825 begin
826 -- It is assumed that all statements may affect the control flow in
827 -- some way. A raise statement may be expanded into a non-statement
828 -- node.
833 --------------------------------
834 -- Is_Immediately_Within_Body --
835 --------------------------------
840 begin
841 return
848 --------------------
849 -- Is_Raise_Idiom --
850 --------------------
856 begin
859 -- Assume that no raise statement has been seen yet
863 -- Examine the statements preceding the input node, skipping
864 -- internally-generated constructs.
869 -- Multiple raise statements violate the idiom
885 -- At this point the node must be preceded by a raise statement,
886 -- and the raise statement has to be the sole statement within
887 -- the enclosing entry or subprogram body.
889 return
896 ------------------------
897 -- Is_Raise_Statement --
898 ------------------------
901 begin
902 -- A raise statement may be transfomed into a Raise_xxx_Error node
904 return
909 -----------------------
910 -- Is_Sole_Statement --
911 -----------------------
916 begin
917 -- The input node appears within the statements of an entry or
918 -- subprogram body. Examine the statements preceding the node.
925 -- The statement is preceded by another statement or a source
926 -- construct. This indicates that the node does not appear by
927 -- itself.
931 then
941 -- The input node is within a construct nested inside the entry or
942 -- subprogram body.
947 ----------------------------------------
948 -- Preceded_By_Control_Flow_Statement --
949 ----------------------------------------
951 function Preceded_By_Control_Flow_Statement
953 is
956 begin
960 -- Examine the statements preceding the input node
973 -- Assume that the node is part of some control flow statement
978 ----------------------------------
979 -- Within_Conditional_Statement --
980 ----------------------------------
985 begin
991 -- Prevent the search from going too far
1003 -- Local variables
1008 -- Start of processing for Check_Infinite_Recursion
1010 begin
1011 -- The call is assumed to be safe when the enclosing subprogram is
1012 -- invoked with actuals other than its formals.
1013 --
1014 -- procedure Proc (F1 : ...; F2 : ...; ...; FN : ...) is
1015 -- begin
1016 -- ...
1017 -- Proc (A1, A2, ..., AN);
1018 -- ...
1019 -- end Proc;
1024 -- The call is assumed to be safe when the invocation of the enclosing
1025 -- subprogram depends on a conditional statement.
1026 --
1027 -- procedure Proc (F1 : ...; F2 : ...; ...; FN : ...) is
1028 -- begin
1029 -- ...
1030 -- if Some_Condition then
1031 -- Proc (F1, F2, ..., FN);
1032 -- end if;
1033 -- ...
1034 -- end Proc;
1039 -- The context of the call is assumed to be safe when the invocation of
1040 -- the enclosing subprogram is preceded by some control flow statement.
1041 --
1042 -- procedure Proc (F1 : ...; F2 : ...; ...; FN : ...) is
1043 -- begin
1044 -- ...
1045 -- if Some_Condition then
1046 -- ...
1047 -- end if;
1048 -- ...
1049 -- Proc (F1, F2, ..., FN);
1050 -- ...
1051 -- end Proc;
1056 -- Detect an idiom where the context of the call is preceded by a single
1057 -- raise statement.
1058 --
1059 -- procedure Proc (F1 : ...; F2 : ...; ...; FN : ...) is
1060 -- begin
1061 -- raise ...;
1062 -- Proc (F1, F2, ..., FN);
1063 -- end Proc;
1069 -- At this point it is certain that infinite recursion will take place
1070 -- as long as the call is executed. Detect a case where the context of
1071 -- the call is the sole source statement within the subprogram body.
1072 --
1073 -- procedure Proc (F1 : ...; F2 : ...; ...; FN : ...) is
1074 -- begin
1075 -- Proc (F1, F2, ..., FN);
1076 -- end Proc;
1077 --
1078 -- Install an explicit raise to prevent the infinite recursion.
1089 -- Otherwise infinite recursion could take place, considering other flow
1090 -- control constructs such as gotos, exit statements, etc.
1092 else
1101 ---------------------------------------
1102 -- Check_No_Direct_Boolean_Operators --
1103 ---------------------------------------
1106 begin
1109 then
1110 -- Restriction only applies to original source code
1117 -- Do style check (but skip if in instance, error is on template)
1126 ------------------------------
1127 -- Check_Parameterless_Call --
1128 ------------------------------
1134 -- If the prefix is of an access_to_subprogram type, the node must be
1135 -- rewritten as a call. Ditto if the prefix is overloaded and all its
1136 -- interpretations are access to subprograms.
1138 ---------------------------
1139 -- Prefix_Is_Access_Subp --
1140 ---------------------------
1146 begin
1147 -- If the context is an attribute reference that can apply to
1148 -- functions, this is never a parameterless call (RM 4.1.4(6)).
1152 in Name_Address | Name_Code_Address | Name_Access
1153 then
1158 return
1161 else
1166 then
1177 -- Start of processing for Check_Parameterless_Call
1179 begin
1180 -- Defend against junk stuff if errors already detected
1187 then
1194 -- If the context expects a value, and the name is a procedure, this is
1195 -- most likely a missing 'Access. Don't try to resolve the parameterless
1196 -- call, error will be caught when the outer call is analyzed.
1201 and then
1203 | N_Function_Call
1204 | N_Procedure_Call_Statement
1205 then
1209 -- Rewrite as call if overloadable entity that is (or could be, in the
1210 -- overloaded case) a function call. If we know for sure that the entity
1211 -- is an enumeration literal, we do not rewrite it.
1213 -- If the entity is the name of an operator, it cannot be a call because
1214 -- operators cannot have default parameters. In this case, this must be
1215 -- a string whose contents coincide with an operator name. Set the kind
1216 -- of the node appropriately.
1224 -- Rewrite as call if it is an explicit dereference of an expression of
1225 -- a subprogram access type, and the subprogram type is not that of a
1226 -- procedure or entry.
1228 or else
1231 -- Rewrite as call if it is a selected component which is a function,
1232 -- this is the case of a call to a protected function (which may be
1233 -- overloaded with other protected operations).
1235 or else
1238 or else
1240 E_Entry | E_Procedure
1243 -- If one of the above three conditions is met, rewrite as call. Apply
1244 -- the rewriting only once.
1246 then
1249 then
1251 -- This may be a prefixed call that was not fully analyzed, e.g.
1252 -- an actual in an instance.
1257 then
1265 -- The node is the name of the parameterless call. Preserve its
1266 -- descendants, which may be complex expressions.
1270 -- If overloaded, overload set belongs to new copy
1274 -- Change node to parameterless function call (note that the
1275 -- Parameter_Associations associations field is left set to Empty,
1276 -- its normal default value since there are no parameters)
1294 --------------------------------
1295 -- Is_Atomic_Ref_With_Address --
1296 --------------------------------
1301 begin
1305 else
1306 declare
1309 begin
1317 -----------------------------
1318 -- Is_Definite_Access_Type --
1319 -----------------------------
1323 begin
1329 ----------------------
1330 -- Is_Predefined_Op --
1331 ----------------------
1334 begin
1335 -- Predefined operators are intrinsic subprograms
1341 -- A call to a back-end builtin is never a predefined operator
1352 -----------------------------
1353 -- Make_Call_Into_Operator --
1354 -----------------------------
1356 procedure Make_Call_Into_Operator
1360 is
1375 -- If the operand is not universal, and the operator is given by an
1376 -- expanded name, verify that the operand has an interpretation with a
1377 -- type defined in the given scope of the operator.
1380 -- Find a type of the given class in package Pack that contains the
1381 -- operator.
1383 ---------------------------
1384 -- Operand_Type_In_Scope --
1385 ---------------------------
1392 begin
1396 else
1410 ---------------
1411 -- Type_In_P --
1412 ---------------
1418 -- Verify that node is not part of the type declaration for the
1419 -- candidate type, which would otherwise be invisible.
1421 -------------
1422 -- In_Decl --
1423 -------------
1429 begin
1438 else
1441 loop
1444 else
1453 -- Start of processing for Type_In_P
1455 begin
1456 -- If the context type is declared in the prefix package, this is the
1457 -- desired base type.
1462 else
1476 -- Start of processing for Make_Call_Into_Operator
1478 begin
1481 -- Ensure that the corresponding operator has the same parent as the
1482 -- original call. This guarantees that parent traversals performed by
1483 -- the ABE mechanism succeed.
1487 -- Binary operator
1497 -- Unary operator
1499 else
1505 -- If the operator is denoted by an expanded name, and the prefix is
1506 -- not Standard, but the operator is a predefined one whose scope is
1507 -- Standard, then this is an implicit_operator, inserted as an
1508 -- interpretation by the procedure of the same name. This procedure
1509 -- overestimates the presence of implicit operators, because it does
1510 -- not examine the type of the operands. Verify now that the operand
1511 -- type appears in the given scope. If right operand is universal,
1512 -- check the other operand. In the case of concatenation, either
1513 -- argument can be the component type, so check the type of the result.
1514 -- If both arguments are literals, look for a type of the right kind
1515 -- defined in the given scope. This elaborate nonsense is brought to
1516 -- you courtesy of b33302a. The type itself must be frozen, so we must
1517 -- find the type of the proper class in the given scope.
1519 -- A final wrinkle is the multiplication operator for fixed point types,
1520 -- which is defined in Standard only, and not in the scope of the
1521 -- fixed point type itself.
1526 -- If this is a package renaming, get renamed entity, which will be
1527 -- the scope of the operands if operaton is type-correct.
1533 -- If the entity being called is defined in the given package, it is
1534 -- a renaming of a predefined operator, and known to be legal.
1538 then
1541 -- Visibility does not need to be checked in an instance: if the
1542 -- operator was not visible in the generic it has been diagnosed
1543 -- already, else there is an implicit copy of it in the instance.
1551 then
1556 -- Ada 2005 AI-420: Predefined equality on Universal_Access is
1557 -- available.
1563 then
1566 else
1575 and then Is_Binary
1577 then
1583 -- Verify that the scope contains a type that corresponds to
1584 -- the given literal. Optimize the case where Pack is Standard.
1605 else
1614 else
1623 then
1626 -- If the type is defined elsewhere, and the operator is not
1627 -- defined in the given scope (by a renaming declaration, e.g.)
1628 -- then this is an error as well. If an extension of System is
1629 -- present, and the type may be defined there, Pack must be
1630 -- System itself.
1637 then
1640 else
1646 then
1653 Error_Msg_NE
1658 -- Detect a mismatch between the context type and the result type
1659 -- in the named package, which is otherwise not detected if the
1660 -- operands are universal. Check is only needed if source entity is
1661 -- an operator, not a function that renames an operator.
1668 and then not In_Instance
1669 then
1672 then
1673 -- Already checked above
1677 -- Operator may be defined in an extension of System
1682 then
1685 else
1686 -- Could we use Wrong_Type here??? (this would require setting
1687 -- Etype (N) to the actual type found where Typ was expected).
1698 else
1702 -- If this is a call to a function that renames a predefined equality,
1703 -- the renaming declaration provides a type that must be used to
1704 -- resolve the operands. This must be done now because resolution of
1705 -- the equality node will not resolve any remaining ambiguity, and it
1706 -- assumes that the first operand is not overloaded.
1711 then
1719 -- Do rewrite setting Comes_From_Source on the result if the original
1720 -- call came from source. Although it is not strictly the case that the
1721 -- operator as such comes from the source, logically it corresponds
1722 -- exactly to the function call in the source, so it should be marked
1723 -- this way (e.g. to make sure that validity checks work fine).
1725 declare
1727 begin
1732 -- If this is an arithmetic operator and the result type is private,
1733 -- the operands and the result must be wrapped in conversion to
1734 -- expose the underlying numeric type and expand the proper checks,
1735 -- e.g. on division.
1739 when N_Op_Add
1740 | N_Op_Divide
1741 | N_Op_Expon
1742 | N_Op_Mod
1743 | N_Op_Multiply
1744 | N_Op_Rem
1745 | N_Op_Subtract
1746 =>
1749 when N_Op_Abs
1750 | N_Op_Minus
1751 | N_Op_Plus
1752 =>
1758 else
1763 -------------------
1764 -- Operator_Kind --
1765 -------------------
1767 function Operator_Kind
1770 is
1773 begin
1774 -- Use CASE statement or array???
1811 else
1815 -- Unary operators
1817 else
1826 else
1834 ----------------------------
1835 -- Preanalyze_And_Resolve --
1836 ----------------------------
1838 procedure Preanalyze_And_Resolve
1842 is
1846 Inside_Preanalysis_Without_Freezing;
1847 begin
1852 Inside_Preanalysis_Without_Freezing :=
1859 -- Normally, we suppress all checks for this preanalysis. There is no
1860 -- point in processing them now, since they will be applied properly
1861 -- and in the proper location when the default expressions reanalyzed
1862 -- and reexpanded later on. We will also have more information at that
1863 -- point for possible suppression of individual checks.
1865 -- However, in SPARK mode, most expansion is suppressed, and this
1866 -- later reanalysis and reexpansion may not occur. SPARK mode does
1867 -- require the setting of checking flags for proof purposes, so we
1868 -- do the SPARK preanalysis without suppressing checks.
1870 -- This special handling for SPARK mode is required for example in the
1871 -- case of Ada 2012 constructs such as quantified expressions, which are
1872 -- expanded in two separate steps.
1876 else
1880 Expander_Mode_Restore;
1885 Inside_Preanalysis_Without_Freezing :=
1889 pragma Assert
1893 ----------------------------
1894 -- Preanalyze_And_Resolve --
1895 ----------------------------
1898 begin
1902 -- Version without context type
1907 begin
1914 Expander_Mode_Restore;
1918 ------------------------------------------
1919 -- Preanalyze_With_Freezing_And_Resolve --
1920 ------------------------------------------
1922 procedure Preanalyze_With_Freezing_And_Resolve
1925 is
1926 begin
1930 ----------------------------------
1931 -- Replace_Actual_Discriminants --
1932 ----------------------------------
1939 -- Comment needed???
1941 -------------------
1942 -- Process_Discr --
1943 -------------------
1948 begin
1954 then
1970 -- Start of processing for Replace_Actual_Discriminants
1972 begin
1976 -- Allow the replacement of concurrent discriminants in GNATprove even
1977 -- though this is a light expansion activity. Note that generic units
1978 -- are not modified.
1983 else
1999 -------------
2000 -- Resolve --
2001 -------------
2017 -- Determine whether a node comes from a predefined library unit or
2018 -- Standard.
2021 -- Try and fix up a literal so that it matches its expected type. New
2022 -- literals are manufactured if necessary to avoid cascaded errors.
2025 -- Additional diagnostics when an ambiguous call has an ambiguous
2026 -- argument (typically a controlling actual).
2029 -- Called when attempt at resolving current expression fails
2031 ------------------------------------
2032 -- Comes_From_Predefined_Lib_Unit --
2033 -------------------------------------
2036 begin
2037 return
2041 --------------------
2042 -- Patch_Up_Value --
2043 --------------------
2046 begin
2063 then
2068 Char_Literal_Value =>
2084 -------------------------------
2085 -- Report_Ambiguous_Argument --
2086 -------------------------------
2093 begin
2097 then
2100 -- Examine possible interpretations, and adapt the message
2101 -- for inherited subprograms declared by a type derivation.
2109 else
2117 -- Additional message and hint if the ambiguity involves an Ada2020
2118 -- container aggregate.
2123 -----------------------
2124 -- Resolution_Failed --
2125 -----------------------
2128 begin
2131 -- Set the type to the desired one to minimize cascaded errors. Note
2132 -- that this is an approximation and does not work in all cases.
2139 -- The caller will return without calling the expander, so we need
2140 -- to set the analyzed flag. Note that it is fine to set Analyzed
2141 -- to True even if we are in the middle of a shallow analysis,
2142 -- (see the spec of sem for more details) since this is an error
2143 -- situation anyway, and there is no point in repeating the
2144 -- analysis later (indeed it won't work to repeat it later, since
2145 -- we haven't got a clear resolution of which entity is being
2146 -- referenced.)
2152 Literal_Aspect_Map :
2158 -- Start of processing for Resolve
2160 begin
2165 -- Access attribute on remote subprogram cannot be used for a non-remote
2166 -- access-to-subprogram type.
2170 | Name_Unrestricted_Access
2171 | Name_Unchecked_Access
2177 then
2178 Error_Msg_N
2184 -- If the context is a Remote_Access_To_Subprogram, access attributes
2185 -- must be resolved with the corresponding fat pointer. There is no need
2186 -- to check for the attribute name since the return type of an
2187 -- attribute is never a remote type.
2192 then
2193 declare
2201 begin
2202 -- Check that Typ is a remote access-to-subprogram type
2206 -- Prefix (N) must statically denote a remote subprogram
2207 -- declared in a package specification.
2211 Attr = Attribute_Unrestricted_Access
2212 then
2227 or else
2229 then
2231 Error_Msg_N
2233 N);
2236 -- If we are generating code in distributed mode, perform
2237 -- semantic checks against corresponding remote entities.
2239 if Expander_Active
2241 then
2242 Check_Subtype_Conformant
2244 Old_Id => Designated_Type
2270 then
2275 -- Return if already analyzed
2282 -- Any case of Any_Type as the Etype value means that we had a
2283 -- previous error.
2292 -- The resolution of an Expression_With_Actions is determined by
2293 -- its Expression, but if the node comes from source it is a
2294 -- Declare_Expression and requires scope management.
2299 then
2302 else
2309 -- If not overloaded, then we know the type, and all that needs doing
2310 -- is to check that this type is compatible with the context.
2316 -- In the overloaded case, we must select the interpretation that
2317 -- is compatible with the context (i.e. the type passed to Resolve)
2319 else
2320 -- Loop through possible interpretations
2329 -- We are only interested in interpretations that are compatible
2330 -- with the expected type, any other interpretations are ignored.
2335 Write_Eol;
2338 else
2339 -- Skip the current interpretation if it is disabled by an
2340 -- abstract operator. This action is performed only when the
2341 -- type against which we are resolving is the same as the
2342 -- type of the interpretation.
2349 then
2357 -- First matching interpretation
2365 -- Matching interpretation that is not the first, maybe an
2366 -- error, but there are some cases where preference rules are
2367 -- used to choose between the two possibilities. These and
2368 -- some more obscure cases are handled in Disambiguate.
2370 else
2371 -- If the current statement is part of a predefined library
2372 -- unit, then all interpretations which come from user level
2373 -- packages should not be considered. Check previous and
2374 -- current one.
2382 -- Previous interpretation must be discarded
2392 -- Otherwise apply further disambiguation steps
2397 -- Disambiguation has succeeded. Skip the remaining
2398 -- interpretations.
2408 else
2409 -- Before we issue an ambiguity complaint, check for the
2410 -- case of a subprogram call where at least one of the
2411 -- arguments is Any_Type, and if so suppress the message,
2412 -- since it is a cascaded error. This can also happen for
2413 -- a generalized indexing operation.
2418 then
2419 declare
2423 begin
2439 Write_Eol;
2452 then
2457 then
2461 -- Not that special case, so issue message using the flag
2462 -- Ambiguous to control printing of the header message
2463 -- only at the start of an ambiguous set.
2468 then
2469 Error_Msg_N
2472 else
2473 Error_Msg_NE -- CODEFIX
2481 Error_Msg_N
2483 else
2484 Error_Msg_N -- CODEFIX
2490 then
2491 Report_Ambiguous_Argument;
2497 -- By default, the error message refers to the candidate
2498 -- interpretation. But if it is a predefined operator, it
2499 -- is implicitly declared at the declaration of the type
2500 -- of the operand. Recover the sloc of that declaration
2501 -- for the error message.
2507 Standard_Standard
2508 then
2513 then
2521 Standard_Standard
2522 then
2527 then
2531 -- If this is an indirect call, use the subprogram_type
2532 -- in the message, to have a meaningful location. Also
2533 -- indicate if this is an inherited operation, created
2534 -- by a type declaration.
2539 then
2541 Error_Msg_Sloc :=
2543 else
2550 then
2551 -- Special-case the message for universal_fixed
2552 -- operators, which are not declared with the type
2553 -- of the operand, but appear forever in Standard.
2557 then
2558 Error_Msg_N
2561 else
2562 Error_Msg_N
2566 elsif
2568 then
2569 Error_Msg_N
2571 else
2572 Error_Msg_N -- CODEFIX
2579 -- We have a matching interpretation, Expr_Type is the type
2580 -- from this interpretation, and Seen is the entity.
2582 -- For an operator, just set the entity name. The type will be
2583 -- set by the specific operator resolution routine.
2590 | N_Character_Literal
2591 | N_Delta_Aggregate
2592 | N_If_Expression
2593 then
2596 -- AI05-0139-2: Expression is overloaded because type has
2597 -- implicit dereference. The context may be the one that
2598 -- requires implicit dereferemce.
2604 -- If the expression is an entity, generate a reference
2605 -- to it, as this is not done for an overloaded construct
2606 -- during analysis.
2610 then
2613 -- Examine access discriminants of entity type,
2614 -- to check whether one of them yields the
2615 -- expected type.
2617 declare
2621 begin
2642 then
2643 -- If the node is a general indexing, the dereference is
2644 -- is inserted when resolving the rewritten form, else
2645 -- insert it now.
2649 then
2653 -- For an explicit dereference, attribute reference, range,
2654 -- short-circuit form (which is not an operator node), or call
2655 -- with a name that is an explicit dereference, there is
2656 -- nothing to be done at this point.
2659 | N_And_Then
2660 | N_Explicit_Dereference
2661 | N_Identifier
2662 | N_Indexed_Component
2663 | N_Or_Else
2664 | N_Range
2665 | N_Selected_Component
2666 | N_Slice
2668 then
2671 -- For procedure or function calls, set the type of the name,
2672 -- and also the entity pointer for the prefix.
2676 then
2683 then
2688 -- For all other cases, just set the type of the Name
2690 else
2698 -- Move to next interpretation
2706 -- At this stage Found indicates whether or not an acceptable
2707 -- interpretation exists. If not, then we have an error, except that if
2708 -- the context is Any_Type as a result of some other error, then we
2709 -- suppress the error report.
2714 -- If type we are looking for is Void, then this is the procedure
2715 -- call case, and the error is simply that what we gave is not a
2716 -- procedure name (we think of procedure calls as expressions with
2717 -- types internally, but the user doesn't think of them this way).
2721 -- Special case message if function used as a procedure
2726 then
2727 Error_Msg_NE
2730 Error_Msg_N
2734 -- Otherwise give general message (not clear what cases this
2735 -- covers, but no harm in providing for them).
2737 else
2743 -- Otherwise we do have a subexpression with the wrong type
2745 -- Check for the case of an allocator which uses an access type
2746 -- instead of the designated type. This is a common error and we
2747 -- specialize the message, posting an error on the operand of the
2748 -- allocator, complaining that we expected the designated type of
2749 -- the allocator.
2755 then
2759 -- Check for view mismatch on Null in instances, for which the
2760 -- view-swapping mechanism has no identifier.
2766 then
2771 -- Check for an aggregate. Sometimes we can get bogus aggregates
2772 -- from misuse of parentheses, and we are about to complain about
2773 -- the aggregate without even looking inside it.
2775 -- Instead, if we have an aggregate of type Any_Composite, then
2776 -- analyze and resolve the component fields, and then only issue
2777 -- another message if we get no errors doing this (otherwise
2778 -- assume that the errors in the aggregate caused the problem).
2782 then
2785 then
2794 -- Disable expansion in any case. If there is a type mismatch
2795 -- it may be fatal to try to expand the aggregate. The flag
2796 -- would otherwise be set to false when the error is posted.
2800 declare
2802 -- Check one aggregate, and set Found to True if we have a
2803 -- definite error in any of its elements
2806 -- Check one element of aggregate and set Found to True if
2807 -- we definitely have an error in the element.
2809 ----------------
2810 -- Check_Aggr --
2811 ----------------
2816 begin
2829 -- If this is a default-initialized component, then
2830 -- there is nothing to check. The box will be
2831 -- replaced by the appropriate call during late
2832 -- expansion.
2836 then
2845 ----------------
2846 -- Check_Elmt --
2847 ----------------
2850 begin
2851 -- If we have a nested aggregate, go inside it (to
2852 -- attempt a naked analyze-resolve of the aggregate can
2853 -- cause undesirable cascaded errors). Do not resolve
2854 -- expression if it needs a type from context, as for
2855 -- integer * fixed expression.
2860 else
2865 then
2875 begin
2880 -- Rewrite Literal as a call if the corresponding literal aspect
2881 -- is set.
2884 and then Present
2886 then
2887 declare
2889 -- Returns the text of a literal node
2891 -------------------
2892 -- Literal_Text --
2893 -------------------
2896 begin
2901 else
2923 Make_Function_Call
2927 begin
2932 else
2937 -- Conversion needed in case of an inherited aspect
2938 -- of a derived type.
2939 --
2940 -- ??? Need to do something different here for downward
2941 -- tagged conversion case (which is only possible in the
2942 -- case of a null extension); the current call to
2943 -- Convert_To results in an error message about an illegal
2944 -- downward conversion.
2954 -- Looks like we have a type error, but check for special case
2955 -- of Address wanted, integer found, with the configuration pragma
2956 -- Allow_Integer_Address active. If we have this case, introduce
2957 -- an unchecked conversion to allow the integer expression to be
2958 -- treated as an Address. The reverse case of integer wanted,
2959 -- Address found, is treated in an analogous manner.
2966 -- Under relaxed RM semantics silently replace occurrences of null
2967 -- by System.Null_Address.
2975 -- That special Allow_Integer_Address check did not apply, so we
2976 -- have a real type error. If an error message was issued already,
2977 -- Found got reset to True, so if it's still False, issue standard
2978 -- Wrong_Type message.
2982 declare
2985 begin
2991 -- Protected operation: retrieve operation name
2995 else
3000 Error_Msg_NE
3006 declare
3010 begin
3017 Error_Msg_NE
3023 else
3027 else
3033 Resolution_Failed;
3036 -- Test if we have more than one interpretation for the context
3039 Resolution_Failed;
3042 -- Only one interpretation
3044 else
3045 -- In Ada 2005, if we have something like "X : T := 2 + 2;", where
3046 -- the "+" on T is abstract, and the operands are of universal type,
3047 -- the above code will have (incorrectly) resolved the "+" to the
3048 -- universal one in Standard. Therefore check for this case and give
3049 -- an error. We can't do this earlier, because it would cause legal
3050 -- cases to get errors (when some other type has an abstract "+").
3056 then
3061 then
3062 Error_Msg_NE
3071 -- Here we have an acceptable interpretation for the context
3073 -- Propagate type information and normalize tree for various
3074 -- predefined operations. If the context only imposes a class of
3075 -- types, rather than a specific type, propagate the actual type
3076 -- downward.
3082 Typ = Any_Discrete
3083 then
3086 -- Any_Fixed is legal in a real context only if a specific fixed-
3087 -- point type is imposed. If Norman Cohen can be confused by this,
3088 -- it deserves a separate message.
3092 then
3099 -- A user-defined operator is transformed into a function call at
3100 -- this point, so that further processing knows that operators are
3101 -- really operators (i.e. are predefined operators). User-defined
3102 -- operators that are intrinsic are just renamings of the predefined
3103 -- ones, and need not be turned into calls either, but if they rename
3104 -- a different operator, we must transform the node accordingly.
3105 -- Instantiations of Unchecked_Conversion are intrinsic but are
3106 -- treated as functions, even if given an operator designator.
3111 then
3116 and then
3118 N_Subprogram_Renaming_Declaration
3119 then
3122 -- If the node is rewritten, it will be fully resolved in
3123 -- Rewrite_Renamed_Operator.
3132 when N_Aggregate =>
3133 Resolve_Aggregate (N, Ctx_Type);
3135 when N_Allocator =>
3136 Resolve_Allocator (N, Ctx_Type);
3138 when N_Short_Circuit =>
3139 Resolve_Short_Circuit (N, Ctx_Type);
3141 when N_Attribute_Reference =>
3142 Resolve_Attribute (N, Ctx_Type);
3144 when N_Case_Expression =>
3145 Resolve_Case_Expression (N, Ctx_Type);
3147 when N_Character_Literal =>
3148 Resolve_Character_Literal (N, Ctx_Type);
3150 when N_Delta_Aggregate =>
3151 Resolve_Delta_Aggregate (N, Ctx_Type);
3153 when N_Expanded_Name =>
3154 Resolve_Entity_Name (N, Ctx_Type);
3156 when N_Explicit_Dereference =>
3157 Resolve_Explicit_Dereference (N, Ctx_Type);
3159 when N_Expression_With_Actions =>
3160 Resolve_Expression_With_Actions (N, Ctx_Type);
3162 when N_Extension_Aggregate =>
3163 Resolve_Extension_Aggregate (N, Ctx_Type);
3165 when N_Function_Call =>
3166 Resolve_Call (N, Ctx_Type);
3168 when N_Identifier =>
3169 Resolve_Entity_Name (N, Ctx_Type);
3171 when N_If_Expression =>
3172 Resolve_If_Expression (N, Ctx_Type);
3174 when N_Indexed_Component =>
3175 Resolve_Indexed_Component (N, Ctx_Type);
3177 when N_Integer_Literal =>
3178 Resolve_Integer_Literal (N, Ctx_Type);
3180 when N_Membership_Test =>
3181 Resolve_Membership_Op (N, Ctx_Type);
3183 when N_Null =>
3184 Resolve_Null (N, Ctx_Type);
3186 when N_Op_And
3187 | N_Op_Or
3188 | N_Op_Xor
3189 =>
3190 Resolve_Logical_Op (N, Ctx_Type);
3192 when N_Op_Eq
3193 | N_Op_Ne
3194 =>
3195 Resolve_Equality_Op (N, Ctx_Type);
3197 when N_Op_Ge
3198 | N_Op_Gt
3199 | N_Op_Le
3200 | N_Op_Lt
3201 =>
3202 Resolve_Comparison_Op (N, Ctx_Type);
3204 when N_Op_Not =>
3205 Resolve_Op_Not (N, Ctx_Type);
3207 when N_Op_Add
3208 | N_Op_Divide
3209 | N_Op_Mod
3210 | N_Op_Multiply
3211 | N_Op_Rem
3212 | N_Op_Subtract
3213 =>
3214 Resolve_Arithmetic_Op (N, Ctx_Type);
3216 when N_Op_Concat =>
3217 Resolve_Op_Concat (N, Ctx_Type);
3219 when N_Op_Expon =>
3220 Resolve_Op_Expon (N, Ctx_Type);
3222 when N_Op_Abs
3223 | N_Op_Minus
3224 | N_Op_Plus
3225 =>
3226 Resolve_Unary_Op (N, Ctx_Type);
3228 when N_Op_Shift =>
3229 Resolve_Shift (N, Ctx_Type);
3231 when N_Procedure_Call_Statement =>
3232 Resolve_Call (N, Ctx_Type);
3234 when N_Operator_Symbol =>
3235 Resolve_Operator_Symbol (N, Ctx_Type);
3237 when N_Qualified_Expression =>
3238 Resolve_Qualified_Expression (N, Ctx_Type);
3240 -- Why is the following null, needs a comment ???
3242 when N_Quantified_Expression =>
3243 null;
3245 when N_Raise_Expression =>
3246 Resolve_Raise_Expression (N, Ctx_Type);
3248 when N_Raise_xxx_Error =>
3249 Set_Etype (N, Ctx_Type);
3251 when N_Range =>
3252 Resolve_Range (N, Ctx_Type);
3254 when N_Real_Literal =>
3255 Resolve_Real_Literal (N, Ctx_Type);
3257 when N_Reference =>
3258 Resolve_Reference (N, Ctx_Type);
3260 when N_Selected_Component =>
3261 Resolve_Selected_Component (N, Ctx_Type);
3263 when N_Slice =>
3264 Resolve_Slice (N, Ctx_Type);
3266 when N_String_Literal =>
3267 Resolve_String_Literal (N, Ctx_Type);
3269 when N_Target_Name =>
3270 Resolve_Target_Name (N, Ctx_Type);
3272 when N_Type_Conversion =>
3273 Resolve_Type_Conversion (N, Ctx_Type);
3275 when N_Unchecked_Expression =>
3276 Resolve_Unchecked_Expression (N, Ctx_Type);
3278 when N_Unchecked_Type_Conversion =>
3279 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
3280 end case;
3282 -- Mark relevant use-type and use-package clauses as effective using
3283 -- the original node because constant folding may have occured and
3284 -- removed references that need to be examined.
3286 if Nkind (Original_Node (N)) in N_Op then
3287 Mark_Use_Clauses (Original_Node (N));
3288 end if;
3290 -- Ada 2012 (AI05-0149): Apply an (implicit) conversion to an
3291 -- expression of an anonymous access type that occurs in the context
3292 -- of a named general access type, except when the expression is that
3293 -- of a membership test. This ensures proper legality checking in
3294 -- terms of allowed conversions (expressions that would be illegal to
3295 -- convert implicitly are allowed in membership tests).
3297 if Ada_Version >= Ada_2012
3298 and then Ekind (Base_Type (Ctx_Type)) = E_General_Access_Type
3299 and then Ekind (Etype (N)) = E_Anonymous_Access_Type
3300 and then Nkind (Parent (N)) not in N_Membership_Test
3301 then
3302 Rewrite (N, Convert_To (Ctx_Type, Relocate_Node (N)));
3303 Analyze_And_Resolve (N, Ctx_Type);
3304 end if;
3306 -- If the subexpression was replaced by a non-subexpression, then
3307 -- all we do is to expand it. The only legitimate case we know of
3308 -- is converting procedure call statement to entry call statements,
3309 -- but there may be others, so we are making this test general.
3311 if Nkind (N) not in N_Subexpr then
3312 Debug_A_Exit ("resolving ", N, " (done)");
3313 Expand (N);
3314 return;
3315 end if;
3317 -- The expression is definitely NOT overloaded at this point, so
3318 -- we reset the Is_Overloaded flag to avoid any confusion when
3319 -- reanalyzing the node.
3321 Set_Is_Overloaded (N, False);
3323 -- Freeze expression type, entity if it is a name, and designated
3324 -- type if it is an allocator (RM 13.14(10,11,13)).
3326 -- Now that the resolution of the type of the node is complete, and
3327 -- we did not detect an error, we can expand this node. We skip the
3328 -- expand call if we are in a default expression, see section
3329 -- "Handling of Default Expressions" in Sem spec.
3331 Debug_A_Exit ("resolving ", N, " (done)");
3333 -- We unconditionally freeze the expression, even if we are in
3334 -- default expression mode (the Freeze_Expression routine tests this
3335 -- flag and only freezes static types if it is set).
3337 -- Ada 2012 (AI05-177): The declaration of an expression function
3338 -- does not cause freezing, but we never reach here in that case.
3339 -- Here we are resolving the corresponding expanded body, so we do
3340 -- need to perform normal freezing.
3342 -- As elsewhere we do not emit freeze node within a generic. We make
3343 -- an exception for entities that are expressions, only to detect
3344 -- misuses of deferred constants and preserve the output of various
3345 -- tests.
3347 if not Inside_A_Generic or else Is_Entity_Name (N) then
3348 Freeze_Expression (N);
3349 end if;
3351 -- Now we can do the expansion
3353 Expand (N);
3354 end if;
3355 end Resolve;
3357 -------------
3358 -- Resolve --
3359 -------------
3361 -- Version with check(s) suppressed
3363 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
3364 begin
3365 if Suppress = All_Checks then
3366 declare
3367 Sva : constant Suppress_Array := Scope_Suppress.Suppress;
3368 begin
3369 Scope_Suppress.Suppress := (others => True);
3370 Resolve (N, Typ);
3371 Scope_Suppress.Suppress := Sva;
3372 end;
3374 else
3375 declare
3376 Svg : constant Boolean := Scope_Suppress.Suppress (Suppress);
3377 begin
3378 Scope_Suppress.Suppress (Suppress) := True;
3379 Resolve (N, Typ);
3380 Scope_Suppress.Suppress (Suppress) := Svg;
3381 end;
3382 end if;
3383 end Resolve;
3385 -------------
3386 -- Resolve --
3387 -------------
3389 -- Version with implicit type
3391 procedure Resolve (N : Node_Id) is
3392 begin
3393 Resolve (N, Etype (N));
3394 end Resolve;
3396 ---------------------
3397 -- Resolve_Actuals --
3398 ---------------------
3400 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
3401 Loc : constant Source_Ptr := Sloc (N);
3402 A : Node_Id;
3403 A_Id : Entity_Id;
3404 A_Typ : Entity_Id := Empty; -- init to avoid warning
3405 F : Entity_Id;
3406 F_Typ : Entity_Id;
3407 Prev : Node_Id := Empty;
3408 Orig_A : Node_Id;
3409 Real_F : Entity_Id := Empty; -- init to avoid warning
3411 Real_Subp : Entity_Id;
3412 -- If the subprogram being called is an inherited operation for
3413 -- a formal derived type in an instance, Real_Subp is the subprogram
3414 -- that will be called. It may have different formal names than the
3415 -- operation of the formal in the generic, so after actual is resolved
3416 -- the name of the actual in a named association must carry the name
3417 -- of the actual of the subprogram being called.
3419 procedure Check_Aliased_Parameter;
3420 -- Check rules on aliased parameters and related accessibility rules
3421 -- in (RM 3.10.2 (10.2-10.4)).
3423 procedure Check_Argument_Order;
3424 -- Performs a check for the case where the actuals are all simple
3425 -- identifiers that correspond to the formal names, but in the wrong
3426 -- order, which is considered suspicious and cause for a warning.
3428 procedure Check_Prefixed_Call;
3429 -- If the original node is an overloaded call in prefix notation,
3431 -- Try_Object_Operation has already verified that there is a valid
3432 -- interpretation, but the form of the actual can only be determined
3433 -- once the primitive operation is identified.
3436 -- Emit an error concerning the illegal usage of an effectively volatile
3437 -- object for reading in interfering context (SPARK RM 7.1.3(10)).
3440 -- If the actual is missing in a call, insert in the actuals list
3441 -- an instance of the default expression. The insertion is always
3442 -- a named association.
3445 -- Check whether T1 and T2, or their full views, are derived from a
3446 -- common type. Used to enforce the restrictions on array conversions
3447 -- of AI95-00246.
3450 -- Predicate to determine whether an actual that is a concatenation
3451 -- will be evaluated statically and does not need a transient scope.
3452 -- This must be determined before the actual is resolved and expanded
3453 -- because if needed the transient scope must be introduced earlier.
3455 -----------------------------
3456 -- Check_Aliased_Parameter --
3457 -----------------------------
3462 begin
3470 else
3477 -- In a generic body assume the worst for generic formals:
3478 -- they can have a constrained partial view (AI05-041).
3484 then
3487 else
3492 else
3504 then
3512 then
3513 Error_Msg_N
3519 --------------------------
3520 -- Check_Argument_Order --
3521 --------------------------
3524 begin
3525 -- Nothing to do if no parameters, or original node is neither a
3526 -- function call nor a procedure call statement (happens in the
3527 -- operator-transformed-to-function call case), or the call is to an
3528 -- operator symbol (which is usually in infix form), or the call does
3529 -- not come from source, or this warning is off.
3531 if not Warn_On_Parameter_Order
3537 N_Defining_Operator_Symbol)
3539 then
3543 declare
3546 begin
3547 -- Nothing to do if only one parameter
3553 -- Here if at least two arguments
3555 declare
3561 -- Set True if an out of order case is found
3563 begin
3564 -- Collect identifier names of actuals, fail if any actual is
3565 -- not a simple identifier, and record max length of name.
3571 else
3577 -- If we got this far, all actuals are identifiers and the list
3578 -- of their names is stored in the Actuals array.
3583 -- If we ran out of formals, that's odd, probably an error
3584 -- which will be detected elsewhere, but abandon the search.
3590 -- If name matches and is in order OK
3595 else
3596 -- If no match, see if it is elsewhere in list and if so
3597 -- flag potential wrong order if type is compatible.
3601 and then
3603 then
3609 -- No match
3617 -- If Formals left over, also probably an error, skip warning
3623 -- Here we give the warning if something was out of order
3626 Error_Msg_N
3633 -------------------------
3634 -- Check_Prefixed_Call --
3635 -------------------------
3644 begin
3645 -- Check whether the call is a prefixed call, with or without
3646 -- additional actuals.
3649 or else
3655 then
3658 then
3659 -- Introduce dereference on object in prefix
3661 New_A :=
3669 then
3670 -- Introduce an implicit 'Access in prefix
3673 Error_Msg_NE
3689 ---------------------------------------
3690 -- Flag_Effectively_Volatile_Objects --
3691 ---------------------------------------
3695 -- Determine whether arbitrary node N denotes an effectively volatile
3696 -- object for reading and if it does, emit an error.
3698 -----------------
3699 -- Flag_Object --
3700 -----------------
3705 begin
3706 -- Do not consider nested function calls because they have already
3707 -- been processed during their own resolution.
3717 then
3718 Error_Msg_N
3730 -- Start of processing for Flag_Effectively_Volatile_Objects
3732 begin
3736 --------------------
3737 -- Insert_Default --
3738 --------------------
3744 begin
3745 -- Missing argument in call, nothing to insert
3750 else
3751 -- Note that we do a full New_Copy_Tree, so that any associated
3752 -- Itypes are properly copied. This may not be needed any more,
3753 -- but it does no harm as a safety measure. Defaults of a generic
3754 -- formal may be out of bounds of the corresponding actual (see
3755 -- cc1311b) and an additional check may be required.
3757 Actval :=
3758 New_Copy_Tree
3763 -- Propagate dimension information, if any.
3769 then
3775 then
3778 then
3779 -- If default is a real literal, do not introduce a
3780 -- conversion whose effect may depend on the run-time
3781 -- size of universal real.
3785 else
3796 -- Resolve aggregates with their base type, to avoid scope
3797 -- anomalies: the subtype was first built in the subprogram
3798 -- declaration, and the current call may be nested.
3802 else
3806 else
3809 -- See note above concerning aggregates
3813 then
3816 -- Resolve entities with their own type, which may differ from
3817 -- the type of a reference in a generic context (the view
3818 -- swapping mechanism did not anticipate the re-analysis of
3819 -- default values in calls).
3824 else
3829 -- If default is a tag indeterminate function call, propagate tag
3830 -- to obtain proper dispatching.
3834 then
3839 -- If the default expression raises constraint error, then just
3840 -- silently replace it with an N_Raise_Constraint_Error node, since
3841 -- we already gave the warning on the subprogram spec. If node is
3842 -- already a Raise_Constraint_Error leave as is, to prevent loops in
3843 -- the warnings removal machinery.
3847 then
3856 Assoc :=
3861 -- Case of insertion is first named actual
3865 then
3872 else
3876 else
3880 -- Case of insertion is not first named actual
3882 else
3883 Set_Next_Named_Actual
3895 -------------------
3896 -- Same_Ancestor --
3897 -------------------
3903 begin
3906 then
3912 then
3919 --------------------------
3920 -- Static_Concatenation --
3921 --------------------------
3924 begin
3931 -- Concatenation is static when both operands are static and
3932 -- the concatenation operator is a predefined one.
3935 and then
3937 and then
3942 declare
3944 begin
3947 and then
3951 else
3957 -- Start of processing for Resolve_Actuals
3959 begin
3960 Check_Argument_Order;
3964 and then In_Instance
3967 then
3969 else
3974 Check_Prefixed_Call;
3988 -- If we have an error in any actual or formal, indicated by a type
3989 -- of Any_Type, then abandon resolution attempt, and set result type
3990 -- to Any_Type. Skip this if the actual is a Raise_Expression, whose
3991 -- type is imposed from context.
3995 then
4002 -- Case where actual is present
4004 -- If the actual is an entity, generate a reference to it now. We
4005 -- do this before the actual is resolved, because a formal of some
4006 -- protected subprogram, or a task discriminant, will be rewritten
4007 -- during expansion, and the source entity reference may be lost.
4012 then
4013 -- Annotate the tree by creating a variable reference marker when
4014 -- the actual denotes a variable reference, in case the reference
4015 -- is folded or optimized away. The variable reference marker is
4016 -- automatically saved for later examination by the ABE Processing
4017 -- phase. The status of the reference is set as follows:
4019 -- status mode
4020 -- read IN, IN OUT
4021 -- write IN OUT, OUT
4023 if Needs_Variable_Reference_Marker
4026 then
4027 Build_Variable_Reference_Marker
4038 then
4045 -- RM 6.4.1(12): For an out parameter that is passed by
4046 -- copy, the formal parameter object is created, and:
4048 -- * For an access type, the formal parameter is initialized
4049 -- from the value of the actual, without checking that the
4050 -- value satisfies any constraint, any predicate, or any
4051 -- exclusion of the null value.
4053 -- * For a scalar type that has the Default_Value aspect
4054 -- specified, the formal parameter is initialized from the
4055 -- value of the actual, without checking that the value
4056 -- satisfies any constraint or any predicate.
4057 -- I do not understand why this case is included??? this is
4058 -- not a case where an OUT parameter is treated as IN OUT.
4060 -- * For a composite type with discriminants or that has
4061 -- implicit initial values for any subcomponents, the
4062 -- behavior is as for an in out parameter passed by copy.
4064 -- Hence for these cases we generate the read reference now
4065 -- (the write reference will be generated later by
4066 -- Note_Possible_Modification).
4069 and then
4071 or else
4073 and then
4075 or else
4078 or else Is_Partially_Initialized_Type
4080 then
4090 then
4091 -- If style checking mode on, check match of formal name
4099 -- If the formal is Out or In_Out, do not resolve and expand the
4100 -- conversion, because it is subsequently expanded into explicit
4101 -- temporaries and assignments. However, the object of the
4102 -- conversion can be resolved. An exception is the case of tagged
4103 -- type conversion with a class-wide actual. In that case we want
4104 -- the tag check to occur and no temporary will be needed (no
4105 -- representation change can occur) and the parameter is passed by
4106 -- reference, so we go ahead and resolve the type conversion.
4107 -- Another exception is the case of reference to component or
4108 -- subcomponent of a bit-packed array, in which case we want to
4109 -- defer expansion to the point the in and out assignments are
4110 -- performed.
4116 then
4117 declare
4120 begin
4121 -- Check RM 4.6 (24.2/2)
4125 then
4126 -- In a view conversion, the conversion must be legal in
4127 -- both directions, and thus both component types must be
4128 -- aliased, or neither (4.6 (8)).
4130 -- Check RM 4.6 (24.8/2)
4134 then
4135 -- This normally illegal conversion is legal in an
4136 -- expanded instance body because of RM 12.3(11).
4137 -- At runtime, conversion must create a new object.
4140 Error_Msg_N
4145 -- Check RM 4.6 (24/3)
4148 -- Check view conv between unrelated by ref array
4149 -- types.
4153 then
4154 Error_Msg_N
4158 -- In Ada 2005 mode, check view conversion component
4159 -- type cannot be private, tagged, or volatile. Note
4160 -- that we only apply this to source conversions. The
4161 -- generated code can contain conversions which are
4162 -- not subject to this test, and we cannot extract the
4163 -- component type in such cases since it is not
4164 -- present.
4168 then
4169 declare
4172 begin
4177 then
4178 Error_Msg_N
4188 -- AI12-0074 & AI12-0377
4189 -- Check 6.4.1: If the mode is out, the actual parameter is
4190 -- a view conversion, and the type of the formal parameter
4191 -- is a scalar type, then either:
4192 -- - the target and operand type both do not have the
4193 -- Default_Value aspect specified; or
4194 -- - the target and operand type both have the
4195 -- Default_Value aspect specified, and there shall exist
4196 -- a type (other than a root numeric type) that is an
4197 -- ancestor of both the target type and the operand
4198 -- type.
4202 then
4205 then
4206 Error_Msg_N
4211 then
4212 Error_Msg_N
4219 -- Resolve expression if conversion is all OK
4224 then
4228 -- If the actual is a function call that returns a limited
4229 -- unconstrained object that needs finalization, create a
4230 -- transient scope for it, so that it can receive the proper
4231 -- finalization list.
4233 elsif Expander_Active
4239 then
4243 -- A small optimization: if one of the actuals is a concatenation
4244 -- create a block around a procedure call to recover stack space.
4245 -- This alleviates stack usage when several procedure calls in
4246 -- the same statement list use concatenation. We do not perform
4247 -- this wrapping for code statements, where the argument is a
4248 -- static string, and we want to preserve warnings involving
4249 -- sequences of such statements.
4251 elsif Expander_Active
4257 then
4261 else
4265 and then
4268 then
4269 Error_Msg_N
4282 -- (Ada 2005: AI-251): If the actual is an allocator whose
4283 -- directly designated type is a class-wide interface, we build
4284 -- an anonymous access type to use it as the type of the
4285 -- allocator. Later, when the subprogram call is expanded, if
4286 -- the interface has a secondary dispatch table the expander
4287 -- will add a type conversion to force the correct displacement
4288 -- of the pointer.
4291 declare
4295 begin
4296 -- Displace the pointer to the object to reference its
4297 -- secondary dispatch table.
4301 then
4307 -- Ada 2005, AI-162:If the actual is an allocator, the
4308 -- innermost enclosing statement is the master of the
4309 -- created object. This needs to be done with expansion
4310 -- enabled only, otherwise the transient scope will not
4311 -- be removed in the expansion of the wrapped construct.
4313 if Expander_Active
4316 then
4317 Establish_Transient_Scope
4327 -- (Ada 2005): The call may be to a primitive operation of a
4328 -- tagged synchronized type, declared outside of the type. In
4329 -- this case the controlling actual must be converted to its
4330 -- corresponding record type, which is the formal type. The
4331 -- actual may be a subtype, either because of a constraint or
4332 -- because it is a generic actual, so use base type to locate
4333 -- concurrent type.
4340 then
4341 -- If the actual is overloaded, look for an interpretation
4342 -- that has a synchronized type.
4347 else
4348 declare
4352 begin
4357 then
4367 declare
4370 begin
4373 else
4377 -- Tagged synchronized type (case 1): the actual is a
4378 -- concurrent type.
4382 then
4384 Unchecked_Convert_To
4388 -- Tagged synchronized type (case 2): the formal is a
4389 -- concurrent type.
4392 and then Present
4397 then
4400 -- Common case
4402 else
4407 -- Not a synchronized operation
4409 else
4417 -- An actual cannot be an untagged formal incomplete type
4422 then
4423 Error_Msg_N
4427 -- has warnings suppressed, then we reset Never_Set_In_Source for
4428 -- the calling entity. The reason for this is to catch cases like
4429 -- GNAT.Spitbol.Patterns.Vstring_Var where the called subprogram
4430 -- uses trickery to modify an IN parameter.
4437 then
4441 -- Perform error checks for IN and IN OUT parameters
4445 -- Check unset reference. For scalar parameters, it is clearly
4446 -- wrong to pass an uninitialized value as either an IN or
4447 -- IN-OUT parameter. For composites, it is also clearly an
4448 -- error to pass a completely uninitialized value as an IN
4449 -- parameter, but the case of IN OUT is trickier. We prefer
4450 -- not to give a warning here. For example, suppose there is
4451 -- a routine that sets some component of a record to False.
4452 -- It is perfectly reasonable to make this IN-OUT and allow
4453 -- either initialized or uninitialized records to be passed
4454 -- in this case.
4456 -- For partially initialized composite values, we also avoid
4457 -- warnings, since it is quite likely that we are passing a
4458 -- partially initialized value and only the initialized fields
4459 -- will in fact be read in the subprogram.
4464 then
4468 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
4469 -- actual to a nested call, since this constitutes a reading of
4470 -- the parameter, which is not allowed.
4475 then
4480 -- In -gnatd.q mode, forget that a given array is constant when
4481 -- it is passed as an IN parameter to a foreign-convention
4482 -- subprogram. This is in case the subprogram evilly modifies the
4483 -- object. Of course, correct code would use IN OUT.
4485 if Debug_Flag_Dot_Q
4491 then
4495 -- Case of OUT or IN OUT parameter
4499 -- For an Out parameter, check for useless assignment. Note
4500 -- that we can't set Last_Assignment this early, because we may
4501 -- kill current values in Resolve_Call, and that call would
4502 -- clobber the Last_Assignment field.
4504 -- Note: call Warn_On_Useless_Assignment before doing the check
4505 -- below for Is_OK_Variable_For_Out_Formal so that the setting
4506 -- of Referenced_As_LHS/Referenced_As_Out_Formal properly
4507 -- reflects the last assignment, not this one.
4514 then
4519 -- Validate the form of the actual. Note that the call to
4520 -- Is_OK_Variable_For_Out_Formal generates the required
4521 -- reference in this case.
4523 -- A call to an initialization procedure for an aggregate
4524 -- component may initialize a nested component of a constant
4525 -- designated object. In this context the object is variable.
4529 then
4535 then
4536 Error_Msg_N
4541 Error_Msg_N
4548 -- What's the following about???
4552 else
4553 Kill_All_Checks;
4562 -- Apply appropriate constraint/predicate checks for IN [OUT] case
4566 -- Apply predicate tests except in certain special cases. Note
4567 -- that it might be more consistent to apply these only when
4568 -- expansion is active (in Exp_Ch6.Expand_Actuals), as we do
4569 -- for the outbound predicate tests ??? In any case indicate
4570 -- the function being called, for better warnings if the call
4571 -- leads to an infinite recursion.
4577 -- Apply required constraint checks
4590 then
4593 -- For view conversions of a discriminated object, apply
4594 -- check to object itself, the conversion alreay has the
4595 -- proper type.
4599 then
4606 then
4612 then
4615 else
4619 -- Ada 2005 (AI-231): Note that the controlling parameter case
4620 -- already existed in Ada 95, which is partially checked
4621 -- elsewhere (see Checks), and we don't want the warning
4622 -- message to differ.
4627 then
4629 Apply_Compile_Time_Constraint_Error
4635 Apply_Compile_Time_Constraint_Error
4644 -- Checks for OUT parameters and IN OUT parameters
4648 -- If there is a type conversion, make sure the return value
4649 -- meets the constraints of the variable before the conversion.
4654 -- Special case here tailored to Exp_Ch6.Is_Legal_Copy,
4655 -- which would prevent the check from being generated.
4656 -- This is for Starlet only though, so long obsolete.
4661 then
4663 else
4664 Apply_Scalar_Range_Check
4668 -- In addition the return value must meet the constraints
4669 -- of the object type (see the comment below).
4673 else
4674 Apply_Range_Check
4678 -- If no conversion, apply scalar range checks and length check
4679 -- based on the subtype of the actual (NOT that of the formal).
4680 -- This indicates that the check takes place on return from the
4681 -- call. During expansion the required constraint checks are
4682 -- inserted. In GNATprove mode, in the absence of expansion,
4683 -- the flag indicates that the returned value is valid.
4685 else
4691 then
4694 else
4699 -- Note: we do not apply the predicate checks for the case of
4700 -- OUT and IN OUT parameters. They are instead applied in the
4701 -- Expand_Actuals routine in Exp_Ch6.
4704 -- An actual associated with an access parameter is implicitly
4705 -- converted to the anonymous access type of the formal and must
4706 -- satisfy the legality checks for access conversions.
4710 Error_Msg_N
4714 -- If the actual is an access selected component of a variable,
4715 -- the call may modify its designated object. It is reasonable
4716 -- to treat this as a potential modification of the enclosing
4717 -- record, to prevent spurious warnings that it should be
4718 -- declared as a constant, because intuitively programmers
4719 -- regard the designated subcomponent as part of the record.
4724 then
4729 -- Check illegal cases of atomic/volatile actual (RM C.6(12,13))
4733 then
4736 then
4737 Error_Msg_NE
4740 Error_Msg_N
4745 then
4746 Error_Msg_NE
4749 Error_Msg_N
4756 then
4757 Error_Msg_N
4759 A);
4760 Error_Msg_NE
4766 -- Check that subprograms don't have improper controlling
4767 -- arguments (RM 3.9.2 (9)).
4769 -- A primitive operation may have an access parameter of an
4770 -- incomplete tagged type, but a dispatching call is illegal
4771 -- if the type is still incomplete.
4777 declare
4779 begin
4783 then
4784 Error_Msg_NE
4795 -- Apply legality rule 3.9.2 (9/1)
4800 and then not In_Instance
4801 then
4806 Error_Msg_NE
4810 -- Apply the checks described in 3.10.2(27): if the context is a
4811 -- specific access-to-object, the actual cannot be class-wide.
4812 -- Use base type to exclude access_to_subprogram cases.
4819 and then
4824 -- Disable these checks for call to imported C++ subprograms
4826 and then not
4830 then
4831 Error_Msg_N
4836 Error_Msg_NE
4841 Check_Aliased_Parameter;
4845 -- If it is a named association, treat the selector_name as a
4846 -- proper identifier, and mark the corresponding entity.
4850 -- Ignore reference in SPARK mode, as it refers to an entity not
4851 -- in scope at the point of reference, so the reference should
4852 -- be ignored for computing effects of subprograms.
4854 and then not GNATprove_Mode
4855 then
4856 -- If subprogram is overridden, use name of formal that
4857 -- is being called.
4863 else
4877 -- The following checks are only relevant when SPARK_Mode is on as
4878 -- they are not standard Ada legality rule. Internally generated
4879 -- temporaries are ignored.
4883 -- An effectively volatile object for reading may act as an
4884 -- actual when the corresponding formal is of a non-scalar
4885 -- effectively volatile type for reading (SPARK RM 7.1.3(10)).
4889 then
4892 -- An effectively volatile object for reading may act as an
4893 -- actual in a call to an instance of Unchecked_Conversion.
4894 -- (SPARK RM 7.1.3(10)).
4899 -- The actual denotes an object
4902 Error_Msg_N
4906 -- Otherwise the actual denotes an expression. Inspect the
4907 -- expression and flag each effectively volatile object
4908 -- for reading as illegal because it apprears within an
4909 -- interfering context. Note that this is usually done in
4910 -- Resolve_Entity_Name, but when the effectively volatile
4911 -- object for reading appears as an actual in a call, the
4912 -- call must be resolved first.
4914 else
4918 -- An effectively volatile variable cannot act as an actual
4919 -- parameter in a procedure call when the variable has enabled
4920 -- property Effective_Reads and the corresponding formal is of
4921 -- mode IN (SPARK RM 7.1.3(10)).
4926 then
4932 then
4933 Error_Msg_NE
4944 -- A formal parameter of a specific tagged type whose related
4945 -- subprogram is subject to pragma Extensions_Visible with value
4946 -- "False" cannot act as an actual in a subprogram with value
4947 -- "True" (SPARK RM 6.1.7(3)).
4951 Extensions_Visible_True
4952 then
4953 Error_Msg_N
4956 Error_Msg_NE
4960 -- The actual parameter of a Ghost subprogram whose formal is of
4961 -- mode IN OUT or OUT must be a Ghost variable (SPARK RM 6.9(12)).
4969 then
4970 Error_Msg_NE
4976 else
4983 -- Case where actual is not present
4985 else
4986 Insert_Default;
4997 -----------------------
4998 -- Resolve_Allocator --
4999 -----------------------
5011 procedure Check_Allocator_Discrim_Accessibility
5014 -- Check that accessibility level associated with an access discriminant
5015 -- initialized in an allocator by the expression Disc_Exp is not deeper
5016 -- than the level of the allocator type Alloc_Typ. An error message is
5017 -- issued if this condition is violated. Specialized checks are done for
5018 -- the cases of a constraint expression which is an access attribute or
5019 -- an access discriminant.
5021 procedure Check_Allocator_Discrim_Accessibility_Exprs
5024 -- Dispatch checks performed by Check_Allocator_Discrim_Accessibility
5025 -- across all expressions within a given conditional expression.
5028 -- If the allocator is an actual in a call, it is allowed to be class-
5029 -- wide when the context is not because it is a controlling actual.
5031 -------------------------------------------
5032 -- Check_Allocator_Discrim_Accessibility --
5033 -------------------------------------------
5035 procedure Check_Allocator_Discrim_Accessibility
5038 is
5039 begin
5042 then
5043 Error_Msg_N
5046 -- When the expression is an Access attribute the level of the prefix
5047 -- object must not be deeper than that of the allocator's type.
5051 Attribute_Access
5054 then
5055 Error_Msg_N
5057 Disc_Exp);
5059 -- When the expression is an access discriminant the check is against
5060 -- the level of the prefix object.
5066 then
5067 Error_Msg_N
5069 Disc_Exp);
5071 -- All other cases are legal
5073 else
5078 -------------------------------------------------
5079 -- Check_Allocator_Discrim_Accessibility_Exprs --
5080 -------------------------------------------------
5082 procedure Check_Allocator_Discrim_Accessibility_Exprs
5085 is
5089 begin
5090 -- When conditional expressions are constant folded we know at
5091 -- compile time which expression to check - so don't bother with
5092 -- the rest of the cases.
5097 -- Non-constant-folded if expressions
5100 -- Check both expressions if they are still present in the face
5101 -- of expansion.
5108 Check_Allocator_Discrim_Accessibility_Exprs
5113 -- Non-constant-folded case expressions
5116 -- Check all alternatives
5120 Check_Allocator_Discrim_Accessibility_Exprs
5126 -- Base case, check the accessibility of the original node of the
5127 -- expression.
5129 else
5134 ----------------------------
5135 -- In_Dispatching_Context --
5136 ----------------------------
5141 begin
5147 -- Start of processing for Resolve_Allocator
5149 begin
5150 -- Replace general access with specific type
5160 -- For qualified expression, resolve the expression using the given
5161 -- subtype (nothing to do for type mark, subtype indication)
5166 and then not In_Dispatching_Context
5167 then
5168 Error_Msg_N
5172 -- Do a full resolution to apply constraint and predicate checks
5177 -- Allocators generated by the build-in-place expansion mechanism
5178 -- are explicitly marked as coming from source but do not need to be
5179 -- checked for limited initialization. To exclude this case, ensure
5180 -- that the parent of the allocator is a source node.
5181 -- The return statement constructed for an Expression_Function does
5182 -- not come from source but requires a limited check.
5186 and then
5188 or else
5192 and then not In_Instance_Body
5193 then
5196 Error_Msg_N
5199 else
5200 Error_Msg_N
5208 -- Calls to build-in-place functions are not currently supported in
5209 -- allocators for access types associated with a simple storage pool.
5210 -- Supporting such allocators may require passing additional implicit
5211 -- parameters to build-in-place functions (or a significant revision
5212 -- of the current b-i-p implementation to unify the handling for
5213 -- multiple kinds of storage pools). ???
5217 then
5218 declare
5221 begin
5223 and then
5224 Present (Get_Rep_Pragma
5226 then
5227 Error_Msg_N
5234 -- A special accessibility check is needed for allocators that
5235 -- constrain access discriminants. The level of the type of the
5236 -- expression used to constrain an access discriminant cannot be
5237 -- deeper than the type of the allocator (in contrast to access
5238 -- parameters, where the level of the actual can be arbitrary).
5240 -- We can't use Valid_Conversion to perform this check because in
5241 -- general the type of the allocator is unrelated to the type of
5242 -- the access discriminant.
5246 then
5253 then
5256 -- Get the first component expression of the aggregate
5266 else
5270 else
5276 Check_Allocator_Discrim_Accessibility_Exprs
5290 else
5295 else
5304 -- For a subtype mark or subtype indication, freeze the subtype
5306 else
5310 Error_Msg_N
5314 -- A special accessibility check is needed for allocators that
5315 -- constrain access discriminants. The level of the type of the
5316 -- expression used to constrain an access discriminant cannot be
5317 -- deeper than the type of the allocator (in contrast to access
5318 -- parameters, where the level of the actual can be arbitrary).
5319 -- We can't use Valid_Conversion to perform this check because
5320 -- in general the type of the allocator is unrelated to the type
5321 -- of the access discriminant.
5326 then
5336 else
5340 Check_Allocator_Discrim_Accessibility_Exprs
5351 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
5352 -- check that the level of the type of the created object is not deeper
5353 -- than the level of the allocator's access type, since extensions can
5354 -- now occur at deeper levels than their ancestor types. This is a
5355 -- static accessibility level check; a run-time check is also needed in
5356 -- the case of an initialized allocator with a class-wide argument (see
5357 -- Expand_Allocator_Expression).
5361 then
5362 declare
5365 begin
5370 else
5376 then
5379 Error_Msg_N
5389 -- Do not apply Ada 2005 accessibility checks on a class-wide
5390 -- allocator if the type given in the allocator is a formal
5391 -- type. A run-time check will be performed in the instance.
5394 Error_Msg_N
5402 -- Check for allocation from an empty storage pool. But do not complain
5403 -- if it's a return statement for a build-in-place function, because the
5404 -- allocator is there just in case the caller uses an allocator. If the
5405 -- caller does use an allocator, it will be caught at the call site.
5409 then
5412 -- If the context is an unchecked conversion, as may happen within an
5413 -- inlined subprogram, the allocator is being resolved with its own
5414 -- anonymous type. In that case, if the target type has a specific
5415 -- storage pool, it must be inherited explicitly by the allocator type.
5419 then
5420 Set_Associated_Storage_Pool
5428 -- Check that an allocator with task parts isn't for a nested access
5429 -- type when restriction No_Task_Hierarchy applies.
5433 then
5437 -- An illegal allocator may be rewritten as a raise Program_Error
5438 -- statement.
5442 -- Avoid coextension processing for an allocator that is the
5443 -- expansion of a build-in-place function call.
5447 N_Qualified_Expression
5449 N_Function_Call
5450 and then Is_Expanded_Build_In_Place_Call
5452 then
5455 else
5456 -- An anonymous access discriminant is the definition of a
5457 -- coextension.
5461 N_Discriminant_Specification
5462 then
5463 declare
5467 begin
5470 -- Ada 2012 AI05-0052: If the designated type of the
5471 -- allocator is limited, then the allocator shall not
5472 -- be used to define the value of an access discriminant
5473 -- unless the discriminated type is immutably limited.
5478 then
5479 Error_Msg_N
5482 N);
5486 -- Avoid marking an allocator as a dynamic coextension if it is
5487 -- within a static construct.
5492 -- Finalization and deallocation of coextensions utilizes an
5493 -- approximate implementation which does not directly adhere
5494 -- to the semantic rules. Warn on potential issues involving
5495 -- coextensions.
5498 Error_Msg_N
5501 else
5502 Error_Msg_N
5508 -- Cleanup for potential static coextensions
5510 else
5514 -- Anonymous access-to-controlled objects are not finalized on
5515 -- time because this involves run-time ownership and currently
5516 -- this property is not available. In rare cases the object may
5517 -- not be finalized at all. Warn on potential issues involving
5518 -- anonymous access-to-controlled objects.
5522 then
5523 Error_Msg_N
5533 -- Report a simple error: if the designated object is a local task,
5534 -- its body has not been seen yet, and its activation will fail an
5535 -- elaboration check.
5542 then
5548 -- Ada 2012 (AI05-0111-3): Detect an attempt to allocate a task or a
5549 -- type with a task component on a subpool. This action must raise
5550 -- Program_Error at runtime.
5556 then
5568 ---------------------------
5569 -- Resolve_Arithmetic_Op --
5570 ---------------------------
5572 -- Used for resolving all arithmetic operators except exponentiation
5583 -- We do the resolution using the base type, because intermediate values
5584 -- in expressions always are of the base type, not a subtype of it.
5587 -- Returns True if N is in a context that expects "any real type"
5590 -- Return True iff given type is Integer or universal real/integer
5593 -- Choose type of integer literal in fixed-point operation to conform
5594 -- to available fixed-point type. T is the type of the other operand,
5595 -- which is needed to determine the expected type of N.
5598 -- Set operand type to T if universal
5600 -------------------------------
5601 -- Expected_Type_Is_Any_Real --
5602 -------------------------------
5605 begin
5606 -- N is the expression after "delta" in a fixed_point_definition;
5607 -- see RM-3.5.9(6):
5610 | N_Decimal_Fixed_Point_Definition
5612 -- N is one of the bounds in a real_range_specification;
5613 -- see RM-3.5.7(5):
5615 | N_Real_Range_Specification
5617 -- N is the expression of a delta_constraint;
5618 -- see RM-J.3(3):
5620 | N_Delta_Constraint;
5623 -----------------------------
5624 -- Is_Integer_Or_Universal --
5625 -----------------------------
5632 begin
5638 else
5644 then
5655 ----------------------------
5656 -- Set_Mixed_Mode_Operand --
5657 ----------------------------
5663 begin
5666 -- A universal integer literal is resolved as standard integer
5667 -- except in the case of a fixed-point result, where we leave it
5668 -- as universal (to be handled by Exp_Fixd later on)
5672 else
5680 then
5681 -- A universal real can appear in a fixed-type context. We resolve
5682 -- the literal with that context, even though this might raise an
5683 -- exception prematurely (the other operand may be zero).
5690 then
5691 -- Integer arg in mixed-mode operation. Resolve with universal
5692 -- type, in case preference rule must be applied.
5698 -- If the operand is part of a fixed multiplication operation,
5699 -- a conversion will be applied to each operand, so resolve it
5700 -- with its own type.
5705 else
5706 -- Not a mixed-mode operation, resolve with context
5713 -- N may itself be a mixed-mode operation, so use context type
5720 then
5721 -- Must be (fixed * fixed) operation, operand must have one
5722 -- compatible interpretation.
5729 then
5730 -- C * F(X) in a fixed context, where C is a real literal or a
5731 -- fixed-point expression. F must have either a fixed type
5732 -- interpretation or an integer interpretation, but not both.
5739 else
5746 else
5754 -- Reanalyze the literal with the fixed type of the context. If
5755 -- context is Universal_Fixed, we are within a conversion, leave
5756 -- the literal as a universal real because there is no usable
5757 -- fixed type, and the target of the conversion plays no role in
5758 -- the resolution.
5760 declare
5764 begin
5767 else
5773 then
5775 else
5783 -- A universal real conditional expression can appear in a fixed-type
5784 -- context and must be resolved with that context to facilitate the
5785 -- code generation in the back end. However, If the context is
5786 -- Universal_fixed (i.e. as an operand of a multiplication/division
5787 -- involving a fixed-point operand) the conditional expression must
5788 -- resolve to a unique visible fixed_point type, normally Duration.
5793 then
5797 else
5801 else
5806 ----------------------
5807 -- Set_Operand_Type --
5808 ----------------------
5811 begin
5814 then
5819 -- Start of processing for Resolve_Arithmetic_Op
5821 begin
5826 then
5830 -- Special-case for mixed-mode universal expressions or fixed point type
5831 -- operation: each argument is resolved separately. The same treatment
5832 -- is required if one of the operands of a fixed point operation is
5833 -- universal real, since in this case we don't do a conversion to a
5834 -- specific fixed-point type (instead the expander handles the case).
5836 -- Set the type of the node to its universal interpretation because
5837 -- legality checks on an exponentiation operand need the context.
5842 then
5853 or else
5856 then
5861 -- If context is a fixed type and one operand is integer, the other
5862 -- is resolved with the type of the context.
5867 then
5874 then
5878 -- If both operands are universal and the context is a floating
5879 -- point type, the operands are resolved to the type of the context.
5885 else
5890 -- Check the rule in RM05-4.5.5(19.1/2) disallowing universal_fixed
5891 -- multiplying operators from being used when the expected type is
5892 -- also universal_fixed. Note that B_Typ will be Universal_Fixed in
5893 -- some cases where the expected type is actually Any_Real;
5894 -- Expected_Type_Is_Any_Real takes care of that case.
5898 then
5902 N_Type_Conversion | N_Unchecked_Type_Conversion
5903 then
5910 else
5914 N_Type_Conversion | N_Unchecked_Type_Conversion
5915 then
5916 Error_Msg_N
5921 -- The expected type is "any real type" in contexts like
5923 -- type T is delta <universal_fixed-expression> ...
5925 -- in which case we need to set the type to Universal_Real
5926 -- so that static expression evaluation will work properly.
5930 else
5940 then
5945 -- If no previous errors, this is only possible if one operand is
5946 -- overloaded and the context is universal. Resolve as such.
5951 else
5953 and then
5955 then
5959 -- If the context is Universal_Fixed and the operands are also
5960 -- universal fixed, this is an error, unless there is only one
5961 -- applicable fixed_point type (usually Duration).
5969 else
5974 else
5979 -- If one of the arguments was resolved to a non-universal type.
5980 -- label the result of the operation itself with the same type.
5981 -- Do the same for the universal argument, if any.
5993 -- Set overflow and division checking bit
6000 -- Give warning if explicit division by zero
6004 then
6010 or else
6013 then
6014 -- Specialize the warning message according to the operation.
6015 -- When SPARK_Mode is On, force a warning instead of an error
6016 -- in that case, as this likely corresponds to deactivated
6017 -- code. The following warnings are for the case
6022 -- For division, we have two cases, for float division
6023 -- of an unconstrained float type, on a machine where
6024 -- Machine_Overflows is false, we don't get an exception
6025 -- at run-time, but rather an infinity or Nan. The Nan
6026 -- case is pretty obscure, so just warn about infinities.
6030 and then not Machine_Overflows_On_Target
6031 then
6032 Error_Msg_N
6036 -- For all other cases, we get a Constraint_Error
6038 else
6039 Apply_Compile_Time_Constraint_Error
6046 Apply_Compile_Time_Constraint_Error
6052 Apply_Compile_Time_Constraint_Error
6057 -- Division by zero can only happen with division, rem,
6058 -- and mod operations.
6064 -- In GNATprove mode, we enable the division check so that
6065 -- GNATprove will issue a message if it cannot be proved.
6071 -- Otherwise just set the flag to check at run time
6073 else
6078 -- If Restriction No_Implicit_Conditionals is active, then it is
6079 -- violated if either operand can be negative for mod, or for rem
6080 -- if both operands can be negative.
6084 then
6085 declare
6092 -- Set if corresponding operand might be negative
6094 begin
6095 Determine_Range
6099 Determine_Range
6103 -- Check if we will be generating conditionals. There are two
6104 -- cases where that can happen, first for REM, the only case
6105 -- is largest negative integer mod -1, where the division can
6106 -- overflow, but we still have to give the right result. The
6107 -- front end generates a test for this annoying case. Here we
6108 -- just test if both operands can be negative (that's what the
6109 -- expander does, so we match its logic here).
6111 -- The second case is mod where either operand can be negative.
6112 -- In this case, the back end has to generate additional tests.
6115 or else
6117 then
6128 ------------------
6129 -- Resolve_Call --
6130 ------------------
6145 begin
6146 -- Preserve relevant elaboration-related attributes of the context which
6147 -- are no longer available or very expensive to recompute once analysis,
6148 -- resolution, and expansion are over.
6150 Mark_Elaboration_Attributes
6156 -- The context imposes a unique interpretation with type Typ on a
6157 -- procedure or function call. Find the entity of the subprogram that
6158 -- yields the expected type, and propagate the corresponding formal
6159 -- constraints on the actuals. The caller has established that an
6160 -- interpretation exists, and emitted an error if not unique.
6162 -- First deal with the case of a call to an access-to-subprogram,
6163 -- dereference made explicit in Analyze_Call.
6169 else
6170 -- Find the interpretation whose type (a subprogram type) has a
6171 -- return type that is compatible with the context. Analysis of
6172 -- the node has established that one exists.
6191 -- If the prefix is not an entity, then resolve it
6197 -- For an indirect call, we always invalidate checks, since we do not
6198 -- know whether the subprogram is local or global. Yes we could do
6199 -- better here, e.g. by knowing that there are no local subprograms,
6200 -- but it does not seem worth the effort. Similarly, we kill all
6201 -- knowledge of current constant values.
6203 Kill_Current_Values;
6205 -- If this is a procedure call which is really an entry call, do
6206 -- the conversion of the procedure call to an entry call. Protected
6207 -- operations use the same circuitry because the name in the call
6208 -- can be an arbitrary expression with special resolution rules.
6212 then
6219 -- Annotate the tree by creating a call marker in case the original
6220 -- call is transformed by expansion. The call marker is automatically
6221 -- saved for later examination by the ABE Processing phase.
6225 -- Kill checks and constant values, as above for indirect case
6226 -- Who knows what happens when another task is activated?
6228 Kill_Current_Values;
6231 -- Normal subprogram call with name established in Resolve
6237 -- Otherwise we must have the case of an overloaded call
6239 else
6242 -- Initialize Nam to prevent warning (we know it will be assigned
6243 -- in the loop below, but the compiler does not know that).
6259 -- Check that a call to Current_Task does not occur in an entry body
6262 declare
6265 begin
6267 loop
6270 -- Exclude calls that occur within the default of a formal
6271 -- parameter of the entry, since those are evaluated outside
6272 -- of the body.
6279 then
6282 Error_Msg_NE
6296 -- Check that a procedure call does not occur in the context of the
6297 -- entry call statement of a conditional or timed entry call. Note that
6298 -- the case of a call to a subprogram renaming of an entry will also be
6299 -- rejected. The test for N not being an N_Entry_Call_Statement is
6300 -- defensive, covering the possibility that the processing of entry
6301 -- calls might reach this point due to later modifications of the code
6302 -- above.
6307 then
6311 -- Ada 2005 (AI-345): If a procedure_call_statement is used
6312 -- for a procedure_or_entry_call, the procedure_name or
6313 -- procedure_prefix of the procedure_call_statement shall denote
6314 -- an entry renamed by a procedure, or (a view of) a primitive
6315 -- subprogram of a limited interface whose first parameter is
6316 -- a controlling parameter.
6321 then
6322 Error_Msg_N
6327 -- Check that this is not a call to a protected procedure or entry from
6328 -- within a protected function.
6332 -- Freeze the subprogram name if not in a spec-expression. Note that
6333 -- we freeze procedure calls as well as function calls. Procedure calls
6334 -- are not frozen according to the rules (RM 13.14(14)) because it is
6335 -- impossible to have a procedure call to a non-frozen procedure in
6336 -- pure Ada, but in the code that we generate in the expander, this
6337 -- rule needs extending because we can generate procedure calls that
6338 -- need freezing.
6340 -- In Ada 2012, expression functions may be called within pre/post
6341 -- conditions of subsequent functions or expression functions. Such
6342 -- calls do not freeze when they appear within generated bodies,
6343 -- (including the body of another expression function) which would
6344 -- place the freeze node in the wrong scope. An expression function
6345 -- is frozen in the usual fashion, by the appearance of a real body,
6346 -- or at the end of a declarative part. However an implicit call to
6347 -- an expression function may appear when it is part of a default
6348 -- expression in a call to an initialization procedure, and must be
6349 -- frozen now, even if the body is inserted at a later point.
6350 -- Otherwise, the call freezes the expression if expander is active,
6351 -- for example as part of an object declaration.
6354 and then not In_Spec_Expression
6356 and then
6359 then
6362 -- Force freeze of expression function in call
6371 -- For a predefined operator, the type of the result is the type imposed
6372 -- by context, except for a predefined operation on universal fixed.
6373 -- Otherwise the type of the call is the type returned by the subprogram
6374 -- being called.
6381 -- If the subprogram returns an array type, and the context requires the
6382 -- component type of that array type, the node is really an indexing of
6383 -- the parameterless call. Resolve as such. A pathological case occurs
6384 -- when the type of the component is an access to the array type. In
6385 -- this case the call is truly ambiguous. If the call is to an intrinsic
6386 -- subprogram, it can't be an indexed component. This check is necessary
6387 -- because if it's Unchecked_Conversion, and we have "type T_Ptr is
6388 -- access T;" and "type T is array (...) of T_Ptr;" (i.e. an array of
6389 -- pointers to the same array), the compiler gets confused and does an
6390 -- infinite recursion.
6393 and then
6396 or else
6399 and then
6402 then
6403 declare
6408 begin
6409 -- If this is a parameterless call there is no ambiguity and the
6410 -- call has the type of the function.
6419 -- Annotate the tree by creating a call marker in case the
6420 -- original call is transformed by expansion. The call marker
6421 -- is automatically saved for later examination by the ABE
6422 -- Processing phase.
6429 then
6430 Error_Msg_N
6432 else
6435 -- The called entity may be an explicit dereference, in which
6436 -- case there is no entity to set.
6444 or else
6446 and then
6448 then
6451 -- Indexed call to a parameterless function
6453 Index_Node :=
6455 Prefix =>
6458 else
6459 -- An Ada 2005 prefixed call to a primitive operation
6460 -- whose first parameter is the prefix. This prefix was
6461 -- prepended to the parameter list, which is actually a
6462 -- list of indexes. Remove the prefix in order to build
6463 -- the proper indexed component.
6465 Index_Node :=
6467 Prefix =>
6470 Parameter_Associations =>
6471 New_List
6476 -- Preserve the parenthesis count of the node
6480 -- Since we are correcting a node classification error made
6481 -- by the parser, we call Replace rather than Rewrite.
6492 -- Annotate the tree by creating a call marker in case
6493 -- the original call is transformed by expansion. The call
6494 -- marker is automatically saved for later examination by
6495 -- the ABE Processing phase.
6506 else
6507 -- If the called function is not declared in the main unit and it
6508 -- returns the limited view of type then use the available view (as
6509 -- is done in Try_Object_Operation) to prevent back-end confusion;
6510 -- for the function entity itself. The call must appear in a context
6511 -- where the nonlimited view is available. If the function entity is
6512 -- in the extended main unit then no action is needed, because the
6513 -- back end handles this case. In either case the type of the call
6514 -- is the nonlimited view.
6518 then
6525 else
6530 -- In the case where the call is to an overloaded subprogram, Analyze
6531 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
6532 -- such a case Normalize_Actuals needs to be called once more to order
6533 -- the actuals correctly. Otherwise the call will have the ordering
6534 -- given by the last overloaded subprogram whether this is the correct
6535 -- one being called or not.
6542 -- In any case, call is fully resolved now. Reset Overload flag, to
6543 -- prevent subsequent overload resolution if node is analyzed again
6548 -- A Ghost entity must appear in a specific context
6554 -- If we are calling the current subprogram from immediately within its
6555 -- body, then that is the case where we can sometimes detect cases of
6556 -- infinite recursion statically. Do not try this in case restriction
6557 -- No_Recursion is in effect anyway, and do it only for source calls.
6562 -- Issue warning for possible infinite recursion in the absence
6563 -- of the No_Recursion restriction.
6569 then
6570 -- Here we detected and flagged an infinite recursion, so we do
6571 -- not need to test the case below for further warnings. Also we
6572 -- are all done if we now have a raise SE node.
6578 -- If call is to immediately containing subprogram, then check for
6579 -- the case of a possible run-time detectable infinite recursion.
6581 else
6585 -- Ada 202x (AI12-0075): Static functions are never allowed
6586 -- to make a recursive call, as specified by 6.8(5.4/5).
6589 Error_Msg_N
6598 -- Although in general case, recursion is not statically
6599 -- checkable, the case of calling an immediately containing
6600 -- subprogram is easy to catch.
6606 -- If the recursive call is to a parameterless subprogram,
6607 -- then even if we can't statically detect infinite
6608 -- recursion, this is pretty suspicious, and we output a
6609 -- warning. Furthermore, we will try later to detect some
6610 -- cases here at run time by expanding checking code (see
6611 -- Detect_Infinite_Recursion in package Exp_Ch6).
6613 -- If the recursive call is within a handler, do not emit a
6614 -- warning, because this is a common idiom: loop until input
6615 -- is correct, catch illegal input in handler and restart.
6621 then
6622 -- For the case of a procedure call. We give the message
6623 -- only if the call is the first statement in a sequence
6624 -- of statements, or if all previous statements are
6625 -- simple assignments. This is simply a heuristic to
6626 -- decrease false positives, without losing too many good
6627 -- warnings. The idea is that these previous statements
6628 -- may affect global variables the procedure depends on.
6629 -- We also exclude raise statements, that may arise from
6630 -- constraint checks and are probably unrelated to the
6631 -- intended control flow.
6635 then
6636 declare
6638 begin
6642 | N_Raise_Constraint_Error
6643 then
6652 -- Do not give warning if we are in a conditional context
6654 declare
6656 begin
6662 then
6667 -- Here warning is to be issued
6683 -- Check obsolescent reference to Ada.Characters.Handling subprogram
6687 -- If subprogram name is a predefined operator, it was given in
6688 -- functional notation. Replace call node with operator node, so
6689 -- that actuals can be resolved appropriately.
6697 then
6703 -- Create a transient scope if the resulting type requires it
6705 -- There are several notable exceptions:
6707 -- a) In init procs, the transient scope overhead is not needed, and is
6708 -- even incorrect when the call is a nested initialization call for a
6709 -- component whose expansion may generate adjust calls. However, if the
6710 -- call is some other procedure call within an initialization procedure
6711 -- (for example a call to Create_Task in the init_proc of the task
6712 -- run-time record) a transient scope must be created around this call.
6714 -- b) Enumeration literal pseudo-calls need no transient scope
6716 -- c) Intrinsic subprograms (Unchecked_Conversion and source info
6717 -- functions) do not use the secondary stack even though the return
6718 -- type may be unconstrained.
6720 -- d) Calls to a build-in-place function, since such functions may
6721 -- allocate their result directly in a target object, and cases where
6722 -- the result does get allocated in the secondary stack are checked for
6723 -- within the specialized Exp_Ch6 procedures for expanding those
6724 -- build-in-place calls.
6726 -- e) Calls to inlinable expression functions do not use the secondary
6727 -- stack (since the call will be replaced by its returned object).
6729 -- f) If the subprogram is marked Inline_Always, then even if it returns
6730 -- an unconstrained type the call does not require use of the secondary
6731 -- stack. However, inlining will only take place if the body to inline
6732 -- is already present. It may not be available if e.g. the subprogram is
6733 -- declared in a child instance.
6735 -- g) If the subprogram is a static expression function and the call is
6736 -- a static call (the actuals are all static expressions), then we never
6737 -- want to create a transient scope (this could occur in the case of a
6738 -- static string-returning call).
6744 then
6752 then
6755 -- A return statement from an ignored Ghost function does not use the
6756 -- secondary stack (or any other one).
6758 elsif Expander_Active
6762 then
6765 -- If the call appears within the bounds of a loop, it will be
6766 -- rewritten and reanalyzed, nothing left to do here.
6773 -- A protected function cannot be called within the definition of the
6774 -- enclosing protected type, unless it is part of a pre/postcondition
6775 -- on another protected operation. This may appear in the entry wrapper
6776 -- created for an entry with preconditions.
6781 and then not In_Spec_Expression
6783 then
6784 Error_Msg_NE
6788 -- Propagate interpretation to actuals, and add default expressions
6789 -- where needed.
6794 -- Overloaded literals are rewritten as function calls, for purpose of
6795 -- resolution. After resolution, we can replace the call with the
6796 -- literal itself.
6802 -- Avoid validation, since it is a static function call
6808 -- If the subprogram is not global, then kill all saved values and
6809 -- checks. This is a bit conservative, since in many cases we could do
6810 -- better, but it is not worth the effort. Similarly, we kill constant
6811 -- values. However we do not need to do this for internal entities
6812 -- (unless they are inherited user-defined subprograms), since they
6813 -- are not in the business of molesting local values.
6815 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
6816 -- kill all checks and values for calls to global subprograms. This
6817 -- takes care of the case where an access to a local subprogram is
6818 -- taken, and could be passed directly or indirectly and then called
6819 -- from almost any context.
6821 -- Note: we do not do this step till after resolving the actuals. That
6822 -- way we still take advantage of the current value information while
6823 -- scanning the actuals.
6825 -- We suppress killing values if we are processing the nodes associated
6826 -- with N_Freeze_Entity nodes. Otherwise the declaration of a tagged
6827 -- type kills all the values as part of analyzing the code that
6828 -- initializes the dispatch tables.
6832 or else Suppress_Value_Tracking_On_Call
6837 then
6838 Kill_Current_Values;
6841 -- If we are warning about unread OUT parameters, this is the place to
6842 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
6843 -- after the above call to Kill_Current_Values (since that call clears
6844 -- the Last_Assignment field of all local variables).
6849 then
6850 declare
6854 begin
6864 then
6874 -- If the subprogram is a primitive operation, check whether or not
6875 -- it is a correct dispatching call.
6879 then
6884 and then not In_Instance
6885 then
6889 -- If this is a dispatching call, generate the appropriate reference,
6890 -- for better source navigation in GNAT Studio.
6894 then
6897 -- Normal case, not a dispatching call: generate a call reference
6899 else
6907 -- Check for violation of restriction No_Specific_Termination_Handlers
6908 -- and warn on a potentially blocking call to Abort_Task.
6912 or else
6914 then
6921 -- A call to Ada.Real_Time.Timing_Events.Set_Handler to set a relative
6922 -- timing event violates restriction No_Relative_Delay (AI-0211). We
6923 -- need to check the second argument to determine whether it is an
6924 -- absolute or relative timing event.
6929 then
6933 -- Issue an error for a call to an eliminated subprogram. This routine
6934 -- will not perform the check if the call appears within a default
6935 -- expression.
6939 -- Implement rule in 12.5.1 (23.3/2): In an instance, if the actual is
6940 -- class-wide and the call dispatches on result in a context that does
6941 -- not provide a tag, the call raises Program_Error.
6944 and then In_Instance
6949 then
6950 -- Verify that none of the formals are controlling
6952 declare
6956 begin
6978 -- Check for calling a function with OUT or IN OUT parameter when the
6979 -- calling context (us right now) is not Ada 2012, so does not allow
6980 -- OUT or IN OUT parameters in function calls. Functions declared in
6981 -- a predefined unit are OK, as they may be called indirectly from a
6982 -- user-declared instantiation.
6988 then
6993 -- Check the dimensions of the actuals in the call. For function calls,
6994 -- propagate the dimensions from the returned type to N.
6998 -- All done, evaluate call and deal with elaboration issues
7006 -- Annotate the tree by creating a call marker in case the original call
7007 -- is transformed by expansion. The call marker is automatically saved
7008 -- for later examination by the ABE Processing phase.
7016 -- Ada 202x (AI12-0075): If the call is a static call to a static
7017 -- expression function, then we want to "inline" the call, replacing
7018 -- it with the folded static result. This is not done if the checking
7019 -- for a potentially static expression is enabled or if an error has
7020 -- been posted on the call (which may be due to the check for recursive
7021 -- calls, in which case we don't want to fall into infinite recursion
7022 -- when doing the inlining).
7024 if not Checking_Potentially_Static_Expression
7028 then
7031 -- In GNATprove mode, expansion is disabled, but we want to inline some
7032 -- subprograms to facilitate formal verification. Indirect calls through
7033 -- a subprogram type or within a generic cannot be inlined. Inlining is
7034 -- performed only for calls subject to SPARK_Mode on.
7036 elsif GNATprove_Mode
7039 and then not Inside_A_Generic
7040 then
7047 -- Nothing to do if the subprogram is not eligible for inlining in
7048 -- GNATprove mode, or inlining is disabled with switch -gnatdm
7052 or else Debug_Flag_M
7053 then
7056 -- Calls cannot be inlined inside assertions, as GNATprove treats
7057 -- assertions as logic expressions. Only issue a message when the
7058 -- body has been seen, otherwise this leads to spurious messages
7059 -- on expression functions.
7063 Cannot_Inline
7067 -- Calls cannot be inlined inside default expressions
7070 Cannot_Inline
7073 -- Calls cannot be inlined inside quantified expressions, which
7074 -- are left in expression form for GNATprove. Since these
7075 -- expressions are only preanalyzed, we need to detect the failure
7076 -- to inline outside of the case for Full_Analysis below.
7079 Cannot_Inline
7082 -- Inlining should not be performed during preanalysis
7086 -- Do not inline calls inside expression functions or functions
7087 -- generated by the front end for subtype predicates, as this
7088 -- would prevent interpreting them as logical formulas in
7089 -- GNATprove. Only issue a message when the body has been seen,
7090 -- otherwise this leads to spurious messages on callees that
7091 -- are themselves expression functions.
7094 and then
7099 then
7102 then
7104 Cannot_Inline
7109 Cannot_Inline
7114 Cannot_Inline
7118 else
7119 Cannot_Inline
7125 -- Cannot inline a call inside the definition of a record type,
7126 -- typically inside the constraints of the type. Calls in
7127 -- default expressions are also not inlined, but this is
7128 -- filtered out above when testing In_Default_Expr.
7131 Cannot_Inline
7134 -- With the one-pass inlining technique, a call cannot be
7135 -- inlined if the corresponding body has not been seen yet.
7138 Cannot_Inline
7141 -- Nothing to do if there is no body to inline, indicating that
7142 -- the subprogram is not suitable for inlining in GNATprove
7143 -- mode.
7148 -- Calls cannot be inlined inside potentially unevaluated
7149 -- expressions, as this would create complex actions inside
7150 -- expressions, that are not handled by GNATprove.
7153 Cannot_Inline
7157 -- Calls cannot be inlined inside the conditions of while
7158 -- loops, as this would create complex actions inside
7159 -- the condition, that are not handled by GNATprove.
7162 Cannot_Inline
7165 -- Do not inline calls which would possibly lead to missing a
7166 -- type conversion check on an input parameter.
7169 Cannot_Inline
7173 -- Otherwise, inline the call, issuing an info message when
7174 -- -gnatd_f is set.
7176 else
7178 Error_Msg_NE
7189 -----------------------------
7190 -- Resolve_Case_Expression --
7191 -----------------------------
7199 begin
7211 -- When the expression is of a scalar subtype different from the
7212 -- result subtype, then insert a conversion to ensure the generation
7213 -- of a constraint check.
7223 -- Apply RM 4.5.7 (17/3): whether the expression is statically or
7224 -- dynamically tagged must be known statically.
7232 Error_Msg_N
7246 -------------------------------
7247 -- Resolve_Character_Literal --
7248 -------------------------------
7254 begin
7255 -- Verify that the character does belong to the type of the context
7260 -- Wide_Wide_Character literals must always be defined, since the set
7261 -- of wide wide character literals is complete, i.e. if a character
7262 -- literal is accepted by the parser, then it is OK for wide wide
7263 -- character (out of range character literals are rejected).
7268 -- Always accept character literal for type Any_Character, which
7269 -- occurs in error situations and in comparisons of literals, both
7270 -- of which should accept all literals.
7275 -- For Standard.Character or a type derived from it, check that the
7276 -- literal is in range.
7283 -- For Standard.Wide_Character or a type derived from it, check that the
7284 -- literal is in range.
7291 -- If the entity is already set, this has already been resolved in a
7292 -- generic context, or comes from expansion. Nothing else to do.
7297 -- Otherwise we have a user defined character type, and we can use the
7298 -- standard visibility mechanisms to locate the referenced entity.
7300 else
7313 -- If we fall through, then the literal does not match any of the
7314 -- entries of the enumeration type. This isn't just a constraint error
7315 -- situation, it is an illegality (see RM 4.2).
7317 Error_Msg_NE
7321 ---------------------------
7322 -- Resolve_Comparison_Op --
7323 ---------------------------
7325 -- Context requires a boolean type, and plays no role in resolution.
7326 -- Processing identical to that for equality operators. The result type is
7327 -- the base type, which matters when pathological subtypes of booleans with
7328 -- limited ranges are used.
7335 begin
7336 -- If this is an intrinsic operation which is not predefined, use the
7337 -- types of its declared arguments to resolve the possibly overloaded
7338 -- operands. Otherwise the operands are unambiguous and specify the
7339 -- expected type.
7344 else
7355 -- Skip remaining processing if already set to Any_Type
7361 -- Deal with other error cases
7365 T = Any_Character
7366 then
7369 else
7377 -- Resolve the operands if types OK
7386 -- Check comparison on unordered enumeration
7390 Error_Msg_NE
7397 -- Evaluate the relation (note we do this after the above check since
7398 -- this Eval call may change N to True/False. Skip this evaluation
7399 -- inside assertions, in order to keep assertions as written by users
7400 -- for tools that rely on these, e.g. GNATprove for loop invariants.
7401 -- Except evaluation is still performed even inside assertions for
7402 -- comparisons between values of universal type, which are useless
7403 -- for static analysis tools, and not supported even by GNATprove.
7407 and then
7409 then
7414 --------------------------------
7415 -- Resolve_Declare_Expression --
7416 --------------------------------
7418 procedure Resolve_Declare_Expression
7421 is
7423 begin
7424 -- Install the scope created for local declarations, if
7425 -- any. The syntax allows a Declare_Expression with no
7426 -- declarations, in analogy with block statements.
7427 -- Note that that scope has no explicit declaration, but
7428 -- appears as the scope of all entities declared therein.
7441 declare
7444 begin
7453 End_Scope;
7455 else
7460 -----------------------------------------
7461 -- Resolve_Discrete_Subtype_Indication --
7462 -----------------------------------------
7464 procedure Resolve_Discrete_Subtype_Indication
7467 is
7471 begin
7479 else
7489 Error_Msg_NE
7492 -- Rewrite the constraint as a range of Typ
7493 -- to allow compilation to proceed further.
7505 else
7509 -- Additionally, we must check that the bounds are compatible
7510 -- with the given subtype, which might be different from the
7511 -- type of the context.
7515 -- ??? If the above check statically detects a Constraint_Error
7516 -- it replaces the offending bound(s) of the range R with a
7517 -- Constraint_Error node. When the itype which uses these bounds
7518 -- is frozen the resulting call to Duplicate_Subexpr generates
7519 -- a new temporary for the bounds.
7521 -- Unfortunately there are other itypes that are also made depend
7522 -- on these bounds, so when Duplicate_Subexpr is called they get
7523 -- a forward reference to the newly created temporaries and Gigi
7524 -- aborts on such forward references. This is probably sign of a
7525 -- more fundamental problem somewhere else in either the order of
7526 -- itype freezing or the way certain itypes are constructed.
7528 -- To get around this problem we call Remove_Side_Effects right
7529 -- away if either bounds of R are a Constraint_Error.
7531 declare
7535 begin
7551 -------------------------
7552 -- Resolve_Entity_Name --
7553 -------------------------
7555 -- Used to resolve identifiers and expanded names
7558 function Is_Assignment_Or_Object_Expression
7561 -- Determine whether node Context denotes an assignment statement or an
7562 -- object declaration whose expression is node Expr.
7565 -- Determine whether Expr is part of an N_Attribute_Reference
7566 -- expression.
7568 ----------------------------------------
7569 -- Is_Assignment_Or_Object_Expression --
7570 ----------------------------------------
7572 function Is_Assignment_Or_Object_Expression
7575 is
7576 begin
7578 N_Assignment_Statement | N_Object_Declaration
7580 then
7583 -- Check whether a construct that yields a name is the expression of
7584 -- an assignment statement or an object declaration.
7587 | N_Explicit_Dereference
7588 | N_Indexed_Component
7589 | N_Selected_Component
7590 | N_Slice
7592 or else
7594 | N_Unchecked_Type_Conversion
7596 then
7597 return
7598 Is_Assignment_Or_Object_Expression
7602 -- Otherwise the context is not an assignment statement or an object
7603 -- declaration.
7605 else
7610 -----------------------------
7611 -- Is_Attribute_Expression --
7612 -----------------------------
7616 begin
7628 -- Local variables
7633 -- Start of processing for Resolve_Entity_Name
7635 begin
7636 -- If garbage from errors, set to Any_Type and return
7643 -- Replace named numbers by corresponding literals. Note that this is
7644 -- the one case where Resolve_Entity_Name must reset the Etype, since
7645 -- it is currently marked as universal.
7655 -- For enumeration literals, we need to make sure that a proper style
7656 -- check is done, since such literals are overloaded, and thus we did
7657 -- not do a style check during the first phase of analysis.
7663 -- Case of (sub)type name appearing in a context where an expression
7664 -- is expected. This is legal if occurrence is a current instance.
7665 -- See RM 8.6 (17/3).
7671 -- Any other use is an error
7673 else
7674 Error_Msg_N
7678 -- Check discriminant use if entity is discriminant in current scope,
7679 -- i.e. discriminant of record or concurrent type currently being
7680 -- analyzed. Uses in corresponding body are unrestricted.
7685 then
7688 -- A parameterless generic function cannot appear in a context that
7689 -- requires resolution.
7694 -- In Ada 83 an OUT parameter cannot be read, but attributes of
7695 -- array types (i.e. bounds and length) are legal.
7703 or else Is_Assignment_Or_Object_Expression
7706 then
7711 -- In all other cases, just do the possible static evaluation
7713 else
7714 -- A deferred constant that appears in an expression must have a
7715 -- completion, unless it has been removed by in-place expansion of
7716 -- an aggregate. A constant that is a renaming does not need
7717 -- initialization.
7723 and then not In_Spec_Expression
7726 then
7730 then
7732 else
7733 Error_Msg_N
7743 -- When the entity appears in a parameter association, retrieve the
7744 -- related subprogram call.
7752 -- The following checks are only relevant when SPARK_Mode is on as
7753 -- they are not standard Ada legality rules.
7757 -- An effectively volatile object for reading must appear in
7758 -- non-interfering context (SPARK RM 7.1.3(10)).
7763 then
7764 SPARK_Msg_N
7769 -- Check for possible elaboration issues with respect to reads of
7770 -- variables. The act of renaming the variable is not considered a
7771 -- read as it simply establishes an alias.
7773 if Legacy_Elaboration_Checks
7775 and then Dynamic_Elaboration_Checks
7777 then
7782 -- The variable may eventually become a constituent of a single
7783 -- protected/task type. Record the reference now and verify its
7784 -- legality when analyzing the contract of the variable
7785 -- (SPARK RM 9.3).
7791 -- A Ghost entity must appear in a specific context
7798 -- We may be resolving an entity within expanded code, so a reference to
7799 -- an entity should be ignored when calculating effective use clauses to
7800 -- avoid inappropriate marking.
7807 -------------------
7808 -- Resolve_Entry --
7809 -------------------
7821 -- If the bounds of the entry family being called depend on task
7822 -- discriminants, build a new index subtype where a discriminant is
7823 -- replaced with the value of the discriminant of the target task.
7824 -- The target task is the prefix of the entry name in the call.
7826 -----------------------
7827 -- Actual_Index_Type --
7828 -----------------------
7838 -- If the bound is given by a discriminant, replace with a reference
7839 -- to the discriminant of the same name in the target task. If the
7840 -- entry name is the target of a requeue statement and the entry is
7841 -- in the current protected object, the bound to be used is the
7842 -- discriminal of the object (see Apply_Range_Check for details of
7843 -- the transformation).
7845 -----------------------------
7846 -- Actual_Discriminant_Ref --
7847 -----------------------------
7853 begin
7858 then
7864 then
7865 -- Note: here Bound denotes a discriminant of the corresponding
7866 -- record type tskV, whose discriminal is a formal of the
7867 -- init-proc tskVIP. What we want is the body discriminal,
7868 -- which is associated to the discriminant of the original
7869 -- concurrent type tsk.
7871 return New_Occurrence_Of
7874 else
7875 Ref :=
7885 -- Start of processing for Actual_Index_Type
7887 begin
7890 then
7893 else
7907 -- Start of processing for Resolve_Entry
7909 begin
7910 -- Find name of entry being called, and resolve prefix of name with its
7911 -- own type. The prefix can be overloaded, and the name and signature of
7912 -- the entry must be taken into account.
7916 -- Case of dealing with entry family within the current tasks
7920 else
7926 -- Entry call to an entry (or entry family) in the current task. This
7927 -- is legal even though the task will deadlock. Rewrite as call to
7928 -- current task.
7930 -- This can also be a call to an entry in an enclosing task. If this
7931 -- is a single task, we have to retrieve its name, because the scope
7932 -- of the entry is the task type, not the object. If the enclosing
7933 -- task is a task type, the identity of the task is given by its own
7934 -- self variable.
7936 -- Finally this can be a requeue on an entry of the same task or
7937 -- protected object.
7944 then
7945 -- S is an enclosing task or protected object. The concurrent
7946 -- declaration has been converted into a type declaration, and
7947 -- the object itself has an object declaration that follows
7948 -- the type in the same declarative part.
7960 -- Call to current task. Will be transformed into call to Self
7967 New_N :=
7970 Selector_Name =>
7977 then
7978 -- Use the entry name (which must be unique at this point) to find
7979 -- the prefix that returns the corresponding task/protected type.
7981 declare
7987 begin
8009 -- We do not resolve the prefix because an Entry_Family has no type,
8010 -- although it has the semantics of an array since it can be indexed.
8011 -- In order to perform the associated range check, we would need to
8012 -- build an array type on the fly and set it on the prefix, but this
8013 -- would be wasteful since only the index type matters. Therefore we
8014 -- attach this index type directly, so that Actual_Index_Expression
8015 -- can pick it up later in order to generate the range check.
8022 -- Generate a reference for the index when it denotes an entity
8028 -- Up to this point the expression could have been the actual in a
8029 -- simple entry call, and be given by a named association.
8033 else
8039 ------------------------
8040 -- Resolve_Entry_Call --
8041 ------------------------
8052 begin
8053 -- We kill all checks here, because it does not seem worth the effort to
8054 -- do anything better, an entry call is a big operation.
8056 Kill_All_Checks;
8058 -- Processing of the name is similar for entry calls and protected
8059 -- operation calls. Once the entity is determined, we can complete
8060 -- the resolution of the actuals.
8062 -- The selector may be overloaded, in the case of a protected object
8063 -- with overloaded functions. The type of the context is used for
8064 -- resolution.
8069 then
8070 declare
8074 begin
8093 -- Simple entry or protected operation call
8106 -- Call to member of entry family
8113 -- We cannot in general check the maximum depth of protected entry calls
8114 -- at compile time. But we can tell that any protected entry call at all
8115 -- violates a specified nesting depth of zero.
8121 -- Use context type to disambiguate a protected function that can be
8122 -- called without actuals and that returns an array type, and where the
8123 -- argument list may be an indexing of the returned value.
8128 and then
8134 and then
8135 Covers
8138 then
8139 declare
8142 begin
8143 Index_Node :=
8145 Prefix =>
8149 -- Since we are correcting a node classification error made by the
8150 -- parser, we call Replace rather than Rewrite.
8163 then
8164 -- Note the entity being called before rewriting the call, so that
8165 -- it appears used at this point.
8169 -- Rewrite as call to the precondition wrapper, adding the task
8170 -- object to the list of actuals. If the call is to a member of an
8171 -- entry family, include the index as well.
8173 declare
8177 begin
8186 New_Call :=
8188 Name =>
8193 -- Preanalyze and resolve new call. Current procedure is called
8194 -- from Resolve_Call, after which expansion will take place.
8201 -- The operation name may have been overloaded. Order the actuals
8202 -- according to the formals of the resolved entity, and set the return
8203 -- type to that of the operation.
8210 -- Reset the Is_Overloaded flag, since resolution is now completed
8212 -- Simple entry call
8217 -- Call to a member of an entry family
8227 -- Create a call reference to the entry
8235 -- Verify that a procedure call cannot masquerade as an entry
8236 -- call where an entry call is expected.
8241 then
8246 then
8251 then
8256 -- After resolution, entry calls and protected procedure calls are
8257 -- changed into entry calls, for expansion. The structure of the node
8258 -- does not change, so it can safely be done in place. Protected
8259 -- function calls must keep their structure because they are
8260 -- subexpressions.
8264 -- A protected operation that is not a function may modify the
8265 -- corresponding object, and cannot apply to a constant. If this
8266 -- is an internal call, the prefix is the type itself.
8272 then
8273 Error_Msg_N
8275 Entry_Name);
8278 declare
8281 begin
8282 Entry_Call :=
8287 -- Inherit relevant attributes from the original call
8289 Set_First_Named_Actual
8292 Set_Is_Elaboration_Checks_OK_Node
8295 Set_Is_Elaboration_Warnings_OK_Node
8298 Set_Is_SPARK_Mode_On_Node
8305 -- Protected functions can return on the secondary stack, in which case
8306 -- we must trigger the transient scope mechanism.
8308 elsif Expander_Active
8310 then
8314 -- Now we know that this is not a call to a function that returns an
8315 -- array type; moreover, we know the name of the called entry. Detect
8316 -- overlapping actuals, just like for a subprogram call.
8322 -------------------------
8323 -- Resolve_Equality_Op --
8324 -------------------------
8326 -- Both arguments must have the same type, and the boolean context does
8327 -- not participate in the resolution. The first pass verifies that the
8328 -- interpretation is not ambiguous, and the type of the left argument is
8329 -- correctly set, or is Any_Type in case of ambiguity. If both arguments
8330 -- are strings or aggregates, allocators, or Null, they are ambiguous even
8331 -- though they carry a single (universal) type. Diagnose this case here.
8339 -- The resolution rule for if expressions requires that each such must
8340 -- have a unique type. This means that if several dependent expressions
8341 -- are of a non-null anonymous access type, and the context does not
8342 -- impose an expected type (as can be the case in an equality operation)
8343 -- the expression must be rejected.
8346 -- Attempt to explain the nature of a redundant comparison with True. If
8347 -- the expression N is too complex, this routine issues a general error
8348 -- message.
8351 -- In the case of allocators and access attributes, the context must
8352 -- provide an indication of the specific access type to be used. If
8353 -- one operand is of such a "generic" access type, check whether there
8354 -- is a specific visible access type that has the same designated type.
8355 -- This is semantically dubious, and of no interest to any real code,
8356 -- but c48008a makes it all worthwhile.
8358 -------------------------
8359 -- Check_If_Expression --
8360 -------------------------
8366 begin
8373 then
8379 ------------------------
8380 -- Explain_Redundancy --
8381 ------------------------
8388 begin
8391 -- Strip the operand down to an entity
8393 loop
8396 else
8401 -- The construct denotes an entity
8406 -- Do not generate an error message when the comparison is done
8407 -- against the enumeration literal Standard.True.
8411 -- Build a customized error message
8438 -- The construct is too complex to disect, issue a general message
8440 else
8445 -----------------------------
8446 -- Find_Unique_Access_Type --
8447 -----------------------------
8454 begin
8456 then
8460 then
8462 else
8474 then
8487 -- Start of processing for Resolve_Equality_Op
8489 begin
8500 T = Any_Character
8501 then
8504 else
8513 then
8522 -- If expressions must have a single type, and if the context does
8523 -- not impose one the dependent expressions cannot be anonymous
8524 -- access types.
8526 -- Why no similar processing for case expressions???
8531 then
8539 -- If the unique type is a class-wide type then it will be expanded
8540 -- into a dispatching call to the predefined primitive. Therefore we
8541 -- check here for potential violation of such restriction.
8547 -- Only warn for redundant equality comparison to True for objects
8548 -- (e.g. "X = True") and operations (e.g. "(X < Y) = True"). For
8549 -- other expressions, it may be a matter of preference to write
8550 -- "Expr = True" or "Expr".
8552 if Warn_On_Redundant_Constructs
8557 and then
8559 or else
8561 then
8562 Error_Msg_N -- CODEFIX
8567 -- If the equality is overloaded and the operands have resolved
8568 -- properly, set the proper equality operator on the node. The
8569 -- current setting is the first one found during analysis, which
8570 -- is not necessarily the one to which the node has resolved.
8573 declare
8577 begin
8580 -- If the equality is user-defined, the type of the operands
8581 -- matches that of the formals. For a predefined operator,
8582 -- it is the scope that matters, given that the predefined
8583 -- equality has Any_Type formals. In either case the result
8584 -- type (most often Boolean) must match the context. The scope
8585 -- is either that of the type, if there is a generated equality
8586 -- (when there is an equality for the component type), or else
8587 -- Standard otherwise.
8591 and then
8595 then
8605 -- If expansion is active and this is an inherited operation,
8606 -- replace it with its ancestor. This must not be done during
8607 -- preanalysis because the type may not be frozen yet, as when
8608 -- the context is a precondition or postcondition.
8621 -- If this is an inequality, it may be the implicit inequality
8622 -- created for a user-defined operation, in which case the corres-
8623 -- ponding equality operation is not intrinsic, and the operation
8624 -- cannot be constant-folded. Else fold.
8629 or else Is_Intrinsic_Subprogram
8631 then
8637 then
8641 -- Ada 2005: If one operand is an anonymous access type, convert the
8642 -- other operand to it, to ensure that the underlying types match in
8643 -- the back-end. Same for access_to_subprogram, and the conversion
8644 -- verifies that the types are subtype conformant.
8646 -- We apply the same conversion in the case one of the operands is a
8647 -- private subtype of the type of the other.
8649 -- Why the Expander_Active test here ???
8651 if Expander_Active
8652 and then
8654 | E_Anonymous_Access_Subprogram_Type
8656 then
8676 ----------------------------------
8677 -- Resolve_Explicit_Dereference --
8678 ----------------------------------
8686 -- The candidate prefix type, if overloaded
8691 begin
8695 -- A useful optimization: check whether the dereference denotes an
8696 -- element of a container, and if so rewrite it as a call to the
8697 -- corresponding Element function.
8699 -- Disabled for now, on advice of ARG. A more restricted form of the
8700 -- predicate might be acceptable ???
8702 -- if Is_Container_Element (N) then
8703 -- return;
8704 -- end if;
8708 -- Use the context type to select the prefix that has the correct
8709 -- designated type. Keep the first match, which will be the inner-
8710 -- most.
8717 then
8722 -- Remove access types that do not match, but preserve access
8723 -- to subprogram interpretations, in case a further dereference
8724 -- is needed (see below).
8737 else
8738 -- If no interpretation covers the designated type of the prefix,
8739 -- this is the pathological case where not all implementations of
8740 -- the prefix allow the interpretation of the node as a call. Now
8741 -- that the expected type is known, Remove other interpretations
8742 -- from prefix, rewrite it as a call, and resolve again, so that
8743 -- the proper call node is generated.
8754 New_N :=
8756 Name =>
8767 -- If not overloaded, resolve P with its own type
8769 else
8773 -- If the prefix might be null, add an access check
8777 then
8781 -- If the designated type is a packed unconstrained array type, and the
8782 -- explicit dereference is not in the context of an attribute reference,
8783 -- then we must compute and set the actual subtype, since it is needed
8784 -- by Gigi. The reason we exclude the attribute case is that this is
8785 -- handled fine by Gigi, and in fact we use such attributes to build the
8786 -- actual subtype. We also exclude generated code (which builds actual
8787 -- subtypes directly if they are needed).
8794 then
8800 -- Note: No Eval processing is required for an explicit dereference,
8801 -- because such a name can never be static.
8805 -------------------------------------
8806 -- Resolve_Expression_With_Actions --
8807 -------------------------------------
8812 -- True if Act is an action of a declare_expression that is allowed in a
8813 -- static declare_expression.
8816 -- True if all actions of N are allowed in a static declare_expression.
8819 -- Expr is an expression with compile-time-known value. This returns the
8820 -- literal node that reprsents that value.
8823 begin
8828 then
8838 -- No other declarations, nor even pragmas, are allowed in a
8839 -- declare expression, so if we see something else, it must be
8840 -- an internally generated expression_with_actions.
8849 begin
8864 begin
8869 else
8878 pragma Assert
8886 begin
8893 -- If the value of the expression is known at compile time, and all
8894 -- of the actions (if any) are suitable, then replace the declare
8895 -- expression with its expression. This allows the declare expression
8896 -- as a whole to be static if appropriate. See AI12-0368.
8902 Rewrite
8909 ----------------------------------
8910 -- Resolve_Generalized_Indexing --
8911 ----------------------------------
8915 begin
8920 ---------------------------
8921 -- Resolve_If_Expression --
8922 ---------------------------
8926 -- When a dependent expression is of a subtype different from
8927 -- the context subtype, then insert a qualification to ensure
8928 -- the generation of a constraint check. This was previously
8929 -- for scalar types. For array types apply a length check, given
8930 -- that the context in general allows sliding, while a qualified
8931 -- expression forces equality of bounds.
8933 -----------------
8934 -- Apply_Check --
8935 -----------------
8941 begin
8946 or else Inside_A_Generic
8947 then
8953 else
8963 -- Local variables
8969 -- Start of processing for Resolve_If_Expression
8971 begin
8972 -- Defend against malformed expressions
8990 -- If ELSE expression present, just resolve using the determined type
8991 -- If type is universal, resolve to any member of the class.
9000 else
9006 -- Apply RM 4.5.7 (17/3): whether the expression is statically or
9007 -- dynamically tagged must be known statically.
9012 then
9018 -- If no ELSE expression is present, root type must be Standard.Boolean
9019 -- and we provide a Standard.True result converted to the appropriate
9020 -- Boolean type (in case it is a derived boolean type).
9023 Else_Expr :=
9028 else
9042 ----------------------------------
9043 -- Resolve_Implicit_Dereference --
9044 ----------------------------------
9049 begin
9050 -- In an instance the proper view may not always be correct for
9051 -- private types, see e.g. Sem_Type.Covers for similar handling.
9056 and then In_Instance
9057 then
9068 -------------------------------
9069 -- Resolve_Indexed_Component --
9070 -------------------------------
9078 begin
9086 -- Use the context type to select the prefix that yields the correct
9087 -- component type.
9089 declare
9096 begin
9103 and then
9104 Covers
9107 then
9116 else
9122 else
9133 else
9140 -- If the prefix's type is an access type, get to the real array type.
9141 -- Note: we do not apply an access check because an explicit dereference
9142 -- will be introduced later, and the check will happen there.
9148 -- If name was overloaded, set component type correctly now.
9149 -- If a misplaced call to an entry family (which has no index types)
9150 -- return. Error will be diagnosed from calling context.
9154 else
9161 -- The prefix may have resolved to a string literal, in which case its
9162 -- etype has a special representation. This is only possible currently
9163 -- if the prefix is a static concatenation, written in functional
9164 -- notation.
9169 else
9184 -- Do not generate the warning on suspicious index if we are analyzing
9185 -- package Ada.Tags; otherwise we will report the warning with the
9186 -- Prims_Ptr field of the dispatch table.
9189 or else not
9191 Ada_Tags)
9192 then
9197 -- If the array type is atomic and the component is not, then this is
9198 -- worth a warning before Ada 2020, since we have a situation where the
9199 -- access to the component may cause extra read/writes of the atomic
9200 -- object, or partial word accesses, both of which may be unexpected.
9206 and then Has_Atomic_Components
9210 then
9211 Error_Msg_N
9213 Error_Msg_N
9218 -----------------------------
9219 -- Resolve_Integer_Literal --
9220 -----------------------------
9223 begin
9228 --------------------------------
9229 -- Resolve_Intrinsic_Operator --
9230 --------------------------------
9239 -- If the operand is a literal, it cannot be the expression in a
9240 -- conversion. Use a qualified expression instead.
9242 ---------------------
9243 -- Convert_Operand --
9244 ---------------------
9250 begin
9252 Res :=
9258 else
9265 -- Start of processing for Resolve_Intrinsic_Operator
9267 begin
9268 -- We must preserve the original entity in a generic setting, so that
9269 -- the legality of the operation can be verified in an instance.
9284 -- If the result or operand types are private, rewrite with unchecked
9285 -- conversions on the operands and the result, to expose the proper
9286 -- underlying numeric type.
9291 then
9296 else
9317 then
9318 -- Add explicit conversion where needed, and save interpretations in
9319 -- case operands are overloaded.
9326 else
9332 else
9342 else
9347 --------------------------------------
9348 -- Resolve_Intrinsic_Unary_Operator --
9349 --------------------------------------
9351 procedure Resolve_Intrinsic_Unary_Operator
9354 is
9359 begin
9378 else
9383 ------------------------
9384 -- Resolve_Logical_Op --
9385 ------------------------
9390 begin
9393 -- Predefined operations on scalar types yield the base type. On the
9394 -- other hand, logical operations on arrays yield the type of the
9395 -- arguments (and the context).
9399 else
9403 -- The following test is required because the operands of the operation
9404 -- may be literals, in which case the resulting type appears to be
9405 -- compatible with a signed integer type, when in fact it is compatible
9406 -- only with modular types. If the context itself is universal, the
9407 -- operation is illegal.
9415 Error_Msg_N
9423 then
9427 -- Replace AND by AND THEN, or OR by OR ELSE, if Short_Circuit_And_Or
9428 -- is active and the result type is standard Boolean (do not mess with
9429 -- ops that return a nonstandard Boolean type, because something strange
9430 -- is going on).
9432 -- Note: you might expect this replacement to be done during expansion,
9433 -- but that doesn't work, because when the pragma Short_Circuit_And_Or
9434 -- is used, no part of the right operand of an "and" or "or" operator
9435 -- should be executed if the left operand would short-circuit the
9436 -- evaluation of the corresponding "and then" or "or else". If we left
9437 -- the replacement to expansion time, then run-time checks associated
9438 -- with such operands would be evaluated unconditionally, due to being
9439 -- before the condition prior to the rewriting as short-circuit forms
9440 -- during expansion.
9442 if Short_Circuit_And_Or
9445 then
9446 -- Mark the corresponding putative SCO operator as truly a logical
9447 -- (and short-circuit) operator.
9460 -- Case of OR changed to OR ELSE
9462 else
9470 -- Return now, since analysis of the rewritten ops will take care of
9471 -- other reference bookkeeping and expression folding.
9487 ---------------------------
9488 -- Resolve_Membership_Op --
9489 ---------------------------
9491 -- The context can only be a boolean type, and does not determine the
9492 -- arguments. Arguments should be unambiguous, but the preference rule for
9493 -- universal types applies.
9503 -- Analysis has determined a unique type for the left operand. Use it as
9504 -- the basis to resolve the disjuncts.
9506 ----------------------------
9507 -- Resolve_Set_Membership --
9508 ----------------------------
9513 begin
9514 -- If the left operand is overloaded, find type compatible with not
9515 -- overloaded alternative of the right operand.
9524 else
9529 -- Unclear how to resolve expression if all alternatives are also
9530 -- overloaded.
9536 else
9545 -- Alternative is an expression, a range
9546 -- or a subtype mark.
9550 then
9557 -- Check for duplicates for discrete case
9560 declare
9569 begin
9570 -- Loop checking duplicates. This is quadratic, but giant sets
9571 -- are unlikely in this context so it's a reasonable choice.
9578 | N_Character_Literal
9579 | N_Has_Entity
9580 then
9597 -- RM 4.5.2 (28.1/3) specifies that for types other than records or
9598 -- limited types, evaluation of a membership test uses the predefined
9599 -- equality for the type. This may be confusing to users, and the
9600 -- following warning appears useful for the most common case.
9604 then
9605 Error_Msg_NE
9607 Error_Msg_N
9612 -- Start of processing for Resolve_Membership_Op
9614 begin
9620 Resolve_Set_Membership;
9624 and then
9626 or else
9629 then
9632 -- Ada 2005 (AI-251): Support the following case:
9634 -- type I is interface;
9635 -- type T is tagged ...
9637 -- function Test (O : I'Class) is
9638 -- begin
9639 -- return O in T'Class.
9640 -- end Test;
9642 -- In this case we have nothing else to do. The membership test will be
9643 -- done at run time.
9649 then
9651 else
9655 -- If mixed-mode operations are present and operands are all literal,
9656 -- the only interpretation involves Duration, which is probably not
9657 -- the intention of the programmer.
9672 then
9678 else
9683 -- Here after resolving membership operation
9690 ------------------
9691 -- Resolve_Null --
9692 ------------------
9697 begin
9698 -- Handle restriction against anonymous null access values This
9699 -- restriction can be turned off using -gnatdj.
9701 -- Ada 2005 (AI-231): Remove restriction
9704 and then not Debug_Flag_J
9707 then
9708 -- In the common case of a call which uses an explicitly null value
9709 -- for an access parameter, give specialized error message.
9712 Error_Msg_N
9715 -- Standard message for all other cases (are there any?)
9717 else
9718 Error_Msg_N
9723 -- Ada 2005 (AI-231): Generate the null-excluding check in case of
9724 -- assignment to a null-excluding object.
9729 then
9732 -- Decide whether to generate an if_statement around our
9733 -- null-excluding check to avoid them on certain internal object
9734 -- declarations by looking at the type the current Init_Proc
9735 -- belongs to.
9737 -- Generate:
9738 -- if T1b_skip_null_excluding_check then
9739 -- [constraint_error "access check failed"]
9740 -- end if;
9742 if Needs_Conditional_Null_Excluding_Check
9744 then
9747 Condition =>
9749 New_External_Name
9751 Then_Statements =>
9752 New_List (
9756 -- Otherwise, simply create the check
9758 else
9763 else
9764 Insert_Action
9772 -- In a distributed context, null for a remote access to subprogram may
9773 -- need to be replaced with a special record aggregate. In this case,
9774 -- return after having done the transformation.
9779 then
9783 -- The null literal takes its type from the context
9788 -----------------------
9789 -- Resolve_Op_Concat --
9790 -----------------------
9794 -- We wish to avoid deep recursion, because concatenations are often
9795 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
9796 -- operands nonrecursively until we find something that is not a simple
9797 -- concatenation (A in this case). We resolve that, and then walk back
9798 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
9799 -- to do the rest of the work at each level. The Parent pointers allow
9800 -- us to avoid recursion, and thus avoid running out of memory. See also
9801 -- Sem_Ch4.Analyze_Concatenation, where a similar approach is used.
9806 begin
9807 -- The following code is equivalent to:
9809 -- Resolve_Op_Concat_First (NN, Typ);
9810 -- Resolve_Op_Concat_Arg (N, ...);
9811 -- Resolve_Op_Concat_Rest (N, Typ);
9813 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
9814 -- operand is a concatenation.
9816 -- Walk down left operands
9818 loop
9827 -- Now (given the above example) NN is A&B and Op1 is A
9829 -- First resolve Op1 ...
9833 -- ... then walk NN back up until we reach N (where we started), calling
9834 -- Resolve_Op_Concat_Rest along the way.
9836 loop
9843 ---------------------------
9844 -- Resolve_Op_Concat_Arg --
9845 ---------------------------
9847 procedure Resolve_Op_Concat_Arg
9852 is
9856 begin
9858 if Is_Comp
9862 then
9864 else
9868 -- If both Array & Array and Array & Component are visible, there is a
9869 -- potential ambiguity that must be reported.
9874 then
9878 -- If the operation is user-defined and not overloaded use its
9879 -- profile. The operation may be a renaming, in which case it has
9880 -- been rewritten, and we want the original profile.
9885 then
9887 Etype
9891 -- Otherwise an aggregate may match both the array type and the
9892 -- component type.
9894 else
9899 else
9903 then
9904 declare
9909 begin
9914 -- Special-case the error message when the overloading is
9915 -- caused by a function that yields an array and can be
9916 -- called without parameters.
9921 Error_Msg_NE
9923 Error_Msg_NE
9927 else
9935 or else
9937 then
9938 Error_Msg_N -- CODEFIX
9956 else
9961 else
9968 -----------------------------
9969 -- Resolve_Op_Concat_First --
9970 -----------------------------
9977 begin
9978 -- The parser folds an enormous sequence of concatenations of string
9979 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
9980 -- in the right operand. If the expression resolves to a predefined "&"
9981 -- operator, all is well. Otherwise, the parser's folding is wrong, so
9982 -- we give an error. See P_Simple_Expression in Par.Ch4.
9987 then
10002 ----------------------------
10003 -- Resolve_Op_Concat_Rest --
10004 ----------------------------
10010 begin
10019 -- If this is not a static concatenation, but the result is a string
10020 -- type (and not an array of strings) ensure that static string operands
10021 -- have their subtypes properly constructed.
10025 then
10031 ----------------------
10032 -- Resolve_Op_Expon --
10033 ----------------------
10038 begin
10039 -- Catch attempts to do fixed-point exponentiation with universal
10040 -- operands, which is a case where the illegality is not caught during
10041 -- normal operator analysis. This is not done in preanalysis mode
10042 -- since the tree is not fully decorated during preanalysis.
10054 then
10064 then
10071 then
10075 -- We do the resolution using the base type, because intermediate values
10076 -- in expressions are always of the base type, not a subtype of it.
10081 -- For integer types, right argument must be in Natural range
10096 -- Evaluate the exponentiation operator for dimensioned type
10099 else
10103 -- Set overflow checking bit. Much cleverer code needed here eventually
10104 -- and perhaps the Resolve routines should be separated for the various
10105 -- arithmetic operations, since they will need different processing. ???
10114 --------------------
10115 -- Resolve_Op_Not --
10116 --------------------
10122 -- This function determines if the parent node is a boolean operator or
10123 -- operation (comparison op, membership test, or short circuit form) and
10124 -- the not in question is the left operand of this operation. Note that
10125 -- if the not is in parens, then false is returned.
10127 -----------------------
10128 -- Parent_Is_Boolean --
10129 -----------------------
10132 begin
10136 else
10138 when N_And_Then
10139 | N_In
10140 | N_Not_In
10141 | N_Op_And
10142 | N_Op_Eq
10143 | N_Op_Ge
10144 | N_Op_Gt
10145 | N_Op_Le
10146 | N_Op_Lt
10147 | N_Op_Ne
10148 | N_Op_Or
10149 | N_Op_Xor
10150 | N_Or_Else
10151 =>
10160 -- Start of processing for Resolve_Op_Not
10162 begin
10163 -- Predefined operations on scalar types yield the base type. On the
10164 -- other hand, logical operations on arrays yield the type of the
10165 -- arguments (and the context).
10169 else
10173 -- Straightforward case of incorrect arguments
10180 -- Special case of probable missing parens
10184 Error_Msg_N
10187 else
10188 Error_Msg_N
10195 -- OK resolution of NOT
10197 else
10198 -- Warn if non-boolean types involved. This is a case like not a < b
10199 -- where a and b are modular, where we will get (not a) < b and most
10200 -- likely not (a < b) was intended.
10202 if Warn_On_Questionable_Missing_Parens
10204 and then Parent_Is_Boolean
10205 then
10209 -- Warn on double negation if checking redundant constructs
10211 if Warn_On_Redundant_Constructs
10216 then
10220 -- Complete resolution and evaluation of NOT
10221 -- If argument is an equality and expected type is boolean, that
10222 -- expected type has no effect on resolution, and there are
10223 -- special rules for resolution of Eq, Neq in the presence of
10224 -- overloaded operands, so we directly call its resolution routines.
10226 declare
10230 begin
10234 then
10240 then
10250 else
10263 -----------------------------
10264 -- Resolve_Operator_Symbol --
10265 -----------------------------
10267 -- Nothing to be done, all resolved already
10273 begin
10277 ----------------------------------
10278 -- Resolve_Qualified_Expression --
10279 ----------------------------------
10287 begin
10290 -- A qualified expression requires an exact match of the type, class-
10291 -- wide matching is not allowed. However, if the qualifying type is
10292 -- specific and the expression has a class-wide type, it may still be
10293 -- okay, since it can be the result of the expansion of a call to a
10294 -- dispatching function, so we also have to check class-wideness of the
10295 -- type of the expression's original node.
10298 or else
10302 then
10306 -- If the target type is unconstrained, then we reset the type of the
10307 -- result from the type of the expression. For other cases, the actual
10308 -- subtype of the expression is the target type. But we avoid doing it
10309 -- for an allocator since this is not needed and might be problematic.
10314 then
10321 -- If we still have a qualified expression after the static evaluation,
10322 -- then apply a scalar range check if needed. The reason that we do this
10323 -- after the Eval call is that otherwise, the application of the range
10324 -- check may convert an illegal static expression and result in warning
10325 -- rather than giving an error (e.g Integer'(Integer'Last + 1)).
10329 then
10333 -- AI12-0100: Once the qualified expression is resolved, check whether
10334 -- operand statisfies a static predicate of the target subtype, if any.
10335 -- In the static expression case, a predicate check failure is an error.
10338 Check_Expression_Against_Static_Predicate
10343 ------------------------------
10344 -- Resolve_Raise_Expression --
10345 ------------------------------
10348 begin
10352 else
10357 -------------------
10358 -- Resolve_Range --
10359 -------------------
10366 -- Returns True if N is of the form X'First .. X'Last where X is the
10367 -- same entity for both attributes.
10369 --------------------
10370 -- First_Last_Ref --
10371 --------------------
10377 begin
10382 then
10383 declare
10386 begin
10390 then
10399 -- Start of processing for Resolve_Range
10401 begin
10407 -- Reanalyze the lower bound after both bounds have been analyzed, so
10408 -- that the range is known to be static or not by now. This may trigger
10409 -- more compile-time evaluation, which is useful for static analysis
10410 -- with GNATprove. This is not needed for compilation or static analysis
10411 -- with CodePeer, as full expansion does that evaluation then.
10418 -- Check for inappropriate range on unordered enumeration type
10422 -- Exclude X'First .. X'Last if X is the same entity for both
10424 and then not First_Last_Ref
10425 then
10427 Error_Msg_NE
10434 -- We have to check the bounds for being within the base range as
10435 -- required for a non-static context. Normally this is automatic and
10436 -- done as part of evaluating expressions, but the N_Range node is an
10437 -- exception, since in GNAT we consider this node to be a subexpression,
10438 -- even though in Ada it is not. The circuit in Sem_Eval could check for
10439 -- this, but that would put the test on the main evaluation path for
10440 -- expressions.
10445 -- Check for an ambiguous range over character literals. This will
10446 -- happen with a membership test involving only literals.
10454 -- If bounds are static, constant-fold them, so size computations are
10455 -- identical between front-end and back-end. Do not perform this
10456 -- transformation while analyzing generic units, as type information
10457 -- would be lost when reanalyzing the constant node in the instance.
10470 --------------------------
10471 -- Resolve_Real_Literal --
10472 --------------------------
10477 begin
10478 -- Special processing for fixed-point literals to make sure that the
10479 -- value is an exact multiple of small where this is required. We skip
10480 -- this for the universal real case, and also for generic types.
10486 then
10487 declare
10494 begin
10495 -- Case of literal is not an exact multiple of the Small
10499 -- For a source program literal for a decimal fixed-point type,
10500 -- this is statically illegal (RM 4.9(36)).
10505 then
10509 -- Generate a warning if literal from source
10512 and then Warn_On_Bad_Fixed_Value
10513 then
10514 Error_Msg_N
10516 N);
10519 -- Replace literal by a value that is the exact representation
10520 -- of a value of the type, i.e. a multiple of the small value,
10521 -- by truncation, since Machine_Rounds is false for all GNAT
10522 -- fixed-point types (RM 4.9(38)).
10532 -- In all cases, set the corresponding integer field
10538 -- Now replace the actual type by the expected type as usual
10544 -----------------------
10545 -- Resolve_Reference --
10546 -----------------------
10551 begin
10552 -- Replace general access with specific type
10560 -- If we are taking the reference of a volatile entity, then treat it as
10561 -- a potential modification of this entity. This is too conservative,
10562 -- but necessary because remove side effects can cause transformations
10563 -- of normal assignments into reference sequences that otherwise fail to
10564 -- notice the modification.
10571 --------------------------------
10572 -- Resolve_Selected_Component --
10573 --------------------------------
10588 -- Check whether this is the initialization of a component within an
10589 -- init proc (by assignment or call to another init proc). If true,
10590 -- there is no need for a discriminant check.
10592 --------------------
10593 -- Init_Component --
10594 --------------------
10597 begin
10598 return Inside_Init_Proc
10604 -- Start of processing for Resolve_Selected_Component
10606 begin
10609 -- Use the context type to select the prefix that has a selector
10610 -- of the correct name and type.
10618 else
10622 -- Locate selected component. For a private prefix the selector
10623 -- can denote a discriminant.
10627 -- The visible components of a class-wide type are those of
10628 -- the root type.
10638 then
10645 else
10649 Error_Msg_N
10654 else
10657 -- There may be an implicit dereference. Retrieve
10658 -- designated record type.
10662 else
10668 -- Resolution chooses the new interpretation.
10669 -- Find the component with the right name.
10674 loop
10691 -- There must be a legal interpretation at this point
10696 -- In general the expected type is the type of the context, not the
10697 -- type of the candidate selected component.
10702 -- The type of the context and that of the component are
10703 -- compatible and in general identical, but if they are anonymous
10704 -- access-to-subprogram types, the relevant type is that of the
10705 -- component. This matters in Unnest_Subprograms mode, where the
10706 -- relevant context is the one in which the type is declared, not
10707 -- the point of use. This determines what activation record to use.
10712 -- When the type of the component is an access to a class-wide type
10713 -- the relevant type is that of the component (since in such case we
10714 -- may need to generate implicit type conversions or dispatching
10715 -- calls).
10720 then
10724 else
10725 -- Resolve prefix with its type
10730 -- Generate cross-reference. We needed to wait until full overloading
10731 -- resolution was complete to do this, since otherwise we can't tell if
10732 -- we are an lvalue or not.
10736 else
10740 -- If the prefix's type is an access type, get to the real record type.
10741 -- Note: we do not apply an access check because an explicit dereference
10742 -- will be introduced later, and the check will happen there.
10748 else
10751 -- If the prefix is an entity it may have a deferred reference set
10752 -- during analysis of the selected component. After resolution we
10753 -- can transform it into a proper reference. This prevents spurious
10754 -- warnings on useless assignments when the same selected component
10755 -- is the actual for an out parameter in a subsequent call.
10759 then
10762 else
10768 -- Set flag for expander if discriminant check required on a component
10769 -- appearing within a variant.
10775 and then
10778 and then not Init_Component
10779 then
10787 -- If the prefix is a record conversion, this may be a renamed
10788 -- discriminant whose bounds differ from those of the original
10789 -- one, so we must ensure that a range check is performed.
10794 then
10798 -- Note: No Eval processing is required, because the prefix is of a
10799 -- record type, or protected type, and neither can possibly be static.
10801 -- If the record type is atomic and the component is not, then this is
10802 -- worth a warning before Ada 2020, since we have a situation where the
10803 -- access to the component may cause extra read/writes of the atomic
10804 -- object, or partial word accesses, both of which may be unexpected.
10811 then
10812 Error_Msg_N
10815 Error_Msg_N
10824 -------------------
10825 -- Resolve_Shift --
10826 -------------------
10833 begin
10834 -- We do the resolution using the base type, because intermediate values
10835 -- in expressions always are of the base type, not a subtype of it.
10848 ---------------------------
10849 -- Resolve_Short_Circuit --
10850 ---------------------------
10857 begin
10858 -- Ensure all actions associated with the left operand (e.g.
10859 -- finalization of transient objects) are fully evaluated locally within
10860 -- an expression with actions. This is particularly helpful for coverage
10861 -- analysis. However this should not happen in generics or if option
10862 -- Minimize_Expression_With_Actions is set.
10865 declare
10867 begin
10875 -- Set Comes_From_Source on L to preserve warnings for unset
10876 -- reference.
10885 -- Check for issuing warning for always False assert/check, this happens
10886 -- when assertions are turned off, in which case the pragma Assert/Check
10887 -- was transformed into:
10889 -- if False and then <condition> then ...
10891 -- and we detect this pattern
10893 if Warn_On_Assertion_Failure
10900 then
10901 declare
10904 begin
10905 -- Special handling of Asssert pragma
10909 then
10910 declare
10912 Original_Node
10913 (Expression
10916 begin
10917 -- Don't warn if original condition is explicit False,
10918 -- since obviously the failure is expected in this case.
10922 then
10925 -- Issue warning. We do not want the deletion of the
10926 -- IF/AND-THEN to take this message with it. We achieve this
10927 -- by making sure that the expanded code points to the Sloc
10928 -- of the expression, not the original pragma.
10930 else
10931 -- Note: Use Error_Msg_F here rather than Error_Msg_N.
10932 -- The source location of the expression is not usually
10933 -- the best choice here. For example, it gets located on
10934 -- the last AND keyword in a chain of boolean expressiond
10935 -- AND'ed together. It is best to put the message on the
10936 -- first character of the assertion, which is the effect
10937 -- of the First_Node call here.
10939 Error_Msg_F
10941 Expression
10946 -- Similar processing for Check pragma
10950 then
10951 -- Don't want to warn if original condition is explicit False
10953 declare
10955 Original_Node
10956 (Expression
10958 begin
10961 then
10964 -- Post warning
10966 else
10967 -- Again use Error_Msg_F rather than Error_Msg_N, see
10968 -- comment above for an explanation of why we do this.
10970 Error_Msg_F
10972 Expression
10980 -- Continue with processing of short circuit
10989 -------------------
10990 -- Resolve_Slice --
10991 -------------------
11000 begin
11003 -- Use the context type to select the prefix that yields the correct
11004 -- array type.
11006 declare
11013 begin
11021 then
11029 else
11034 else
11045 else
11051 -- If the prefix's type is an access type, get to the real array type.
11052 -- Note: we do not apply an access check because an explicit dereference
11053 -- will be introduced later, and the check will happen there.
11058 -- If the prefix is an access to an unconstrained array, we must use
11059 -- the actual subtype of the object to perform the index checks. The
11060 -- object denoted by the prefix is implicit in the node, so we build
11061 -- an explicit representation for it in order to compute the actual
11062 -- subtype.
11067 declare
11071 begin
11082 then
11085 -- If the name is a selected component that depends on discriminants,
11086 -- build an actual subtype for it. This can happen only when the name
11087 -- itself is overloaded; otherwise the actual subtype is created when
11088 -- the selected component is analyzed.
11091 and then Full_Analysis
11093 then
11094 declare
11097 begin
11102 -- Maybe this should just be "else", instead of checking for the
11103 -- specific case of slice??? This is needed for the case where the
11104 -- prefix is an Image attribute, which gets expanded to a slice, and so
11105 -- has a constrained subtype which we want to use for the slice range
11106 -- check applied below (the range check won't get done if the
11107 -- unconstrained subtype of the 'Image is used).
11113 -- Obtain the type of the array index
11117 else
11121 -- If name was overloaded, set slice type correctly now
11125 -- Handle the generation of a range check that compares the array index
11126 -- against the discrete_range. The check is not applied to internally
11127 -- built nodes associated with the expansion of dispatch tables. Check
11128 -- that Ada.Tags has already been loaded to avoid extra dependencies on
11129 -- the unit.
11131 if Tagged_Type_Expansion
11137 then
11140 -- The discrete_range is specified by a subtype indication. Create a
11141 -- shallow copy and inherit the type, parent and source location from
11142 -- the discrete_range. This ensures that the range check is inserted
11143 -- relative to the slice and that the runtime exception points to the
11144 -- proper construct.
11153 -- The discrete_range is a regular range. Resolve the bounds and remove
11154 -- their side effects.
11156 else
11173 -- Check bad use of type with predicates
11175 declare
11178 begin
11181 then
11183 else
11188 Bad_Predicated_Subtype_Use
11193 -- Otherwise here is where we check suspicious indexes
11205 ----------------------------
11206 -- Resolve_String_Literal --
11207 ----------------------------
11218 begin
11219 -- For a string appearing in a concatenation, defer creation of the
11220 -- string_literal_subtype until the end of the resolution of the
11221 -- concatenation, because the literal may be constant-folded away. This
11222 -- is a useful optimization for long concatenation expressions.
11224 -- If the string is an aggregate built for a single character (which
11225 -- happens in a non-static context) or a is null string to which special
11226 -- checks may apply, we build the subtype. Wide strings must also get a
11227 -- string subtype if they come from a one character aggregate. Strings
11228 -- generated by attributes might be static, but it is often hard to
11229 -- determine whether the enclosing context is static, so we generate
11230 -- subtypes for them as well, thus losing some rarer optimizations ???
11231 -- Same for strings that come from a static conversion.
11233 Need_Check :=
11242 -- If the resolving type is itself a string literal subtype, we can just
11243 -- reuse it, since there is no point in creating another.
11249 and then not Need_Check
11251 | N_Attribute_Reference
11252 | N_Qualified_Expression
11253 | N_Type_Conversion
11254 then
11257 -- Do not generate a string literal subtype for the default expression
11258 -- of a formal parameter in GNATprove mode. This is because the string
11259 -- subtype is associated with the freezing actions of the subprogram,
11260 -- however freezing is disabled in GNATprove mode and as a result the
11261 -- subtype is unavailable.
11263 elsif GNATprove_Mode
11265 then
11268 -- Otherwise we must create a string literal subtype. Note that the
11269 -- whole idea of string literal subtypes is simply to avoid the need
11270 -- for building a full fledged array subtype for each literal.
11272 else
11278 or else Need_Check
11279 then
11286 then
11292 -- The validity of a null string has been checked in the call to
11293 -- Eval_String_Literal.
11298 -- Always accept string literal with component type Any_Character, which
11299 -- occurs in error situations and in comparisons of literals, both of
11300 -- which should accept all literals.
11305 -- If the type is bit-packed, then we always transform the string
11306 -- literal into a full fledged aggregate.
11311 -- Deal with cases of Wide_Wide_String, Wide_String, and String
11313 else
11314 -- For Standard.Wide_Wide_String, or any other type whose component
11315 -- type is Standard.Wide_Wide_Character, we know that all the
11316 -- characters in the string must be acceptable, since the parser
11317 -- accepted the characters as valid character literals.
11322 -- For the case of Standard.String, or any other type whose component
11323 -- type is Standard.Character, we must make sure that there are no
11324 -- wide characters in the string, i.e. that it is entirely composed
11325 -- of characters in range of type Character.
11327 -- If the string literal is the result of a static concatenation, the
11328 -- test has already been performed on the components, and need not be
11329 -- repeated.
11333 then
11337 -- If we are out of range, post error. This is one of the
11338 -- very few places that we place the flag in the middle of
11339 -- a token, right under the offending wide character. Not
11340 -- quite clear if this is right wrt wide character encoding
11341 -- sequences, but it's only an error message.
11343 Error_Msg
11350 -- For the case of Standard.Wide_String, or any other type whose
11351 -- component type is Standard.Wide_Character, we must make sure that
11352 -- there are no wide characters in the string, i.e. that it is
11353 -- entirely composed of characters in range of type Wide_Character.
11355 -- If the string literal is the result of a static concatenation,
11356 -- the test has already been performed on the components, and need
11357 -- not be repeated.
11361 then
11365 -- If we are out of range, post error. This is one of the
11366 -- very few places that we place the flag in the middle of
11367 -- a token, right under the offending wide character.
11369 -- This is not quite right, because characters in general
11370 -- will take more than one character position ???
11372 Error_Msg
11379 -- If the root type is not a standard character, then we will convert
11380 -- the string into an aggregate and will let the aggregate code do
11381 -- the checking. Standard Wide_Wide_Character is also OK here.
11383 else
11387 -- See if the component type of the array corresponding to the string
11388 -- has compile time known bounds. If yes we can directly check
11389 -- whether the evaluation of the string will raise constraint error.
11390 -- Otherwise we need to transform the string literal into the
11391 -- corresponding character aggregate and let the aggregate code do
11392 -- the checking. We use the same transformation if the component
11393 -- type has a static predicate, which will be applied to each
11394 -- character when the aggregate is resolved.
11398 -- Check for the case of full range, where we are definitely OK
11404 -- Here the range is not the complete base type range, so check
11406 declare
11414 begin
11417 then
11423 then
11424 Apply_Compile_Time_Constraint_Error
11426 CE_Range_Check_Failed,
11439 -- If we got here we meed to transform the string literal into the
11440 -- equivalent qualified positional array aggregate. This is rather
11441 -- heavy artillery for this situation, but it is hard work to avoid.
11443 declare
11448 begin
11449 -- Build the character literals, we give them source locations that
11450 -- correspond to the string positions, which is a bit tricky given
11451 -- the possible presence of wide character escape sequences.
11465 -- Should we have a call to Skip_Wide here ???
11467 -- ??? else
11468 -- Skip_Wide (P);
11476 Expression =>
11483 -------------------------
11484 -- Resolve_Target_Name --
11485 -------------------------
11488 begin
11492 -----------------------------
11493 -- Resolve_Type_Conversion --
11494 -----------------------------
11506 -- Set to False to suppress cases where we want to suppress the test
11507 -- for redundancy to avoid possible false positives on this warning.
11509 begin
11510 if not Conv_OK
11512 then
11516 -- If the Operand Etype is Universal_Fixed, then the conversion is
11517 -- never redundant. We need this check because by the time we have
11518 -- finished the rather complex transformation, the conversion looks
11519 -- redundant when it is not.
11524 -- If the operand is marked as Any_Fixed, then special processing is
11525 -- required. This is also a case where we suppress the test for a
11526 -- redundant conversion, since most certainly it is not redundant.
11531 -- Mixed-mode operation involving a literal. Context must be a fixed
11532 -- type which is applied to the literal subsequently.
11534 -- Multiplication and division involving two fixed type operands must
11535 -- yield a universal real because the result is computed in arbitrary
11536 -- precision.
11542 then
11548 or else
11550 then
11551 -- Return if expression is ambiguous
11556 -- If nothing else, the available fixed type is Duration
11558 else
11562 -- Resolve the real operand with largest available precision
11566 else
11572 -- If the operand is a literal (it could be a non-static and
11573 -- illegal exponentiation) check whether the use of Duration
11574 -- is potentially inaccurate.
11579 then
11580 Error_Msg_N
11583 Error_Msg_N
11590 then
11593 else
11604 -- Note: we do the Eval_Type_Conversion call before applying the
11605 -- required checks for a subtype conversion. This is important, since
11606 -- both are prepared under certain circumstances to change the type
11607 -- conversion to a constraint error node, but in the case of
11608 -- Eval_Type_Conversion this may reflect an illegality in the static
11609 -- case, and we would miss the illegality (getting only a warning
11610 -- message), if we applied the type conversion checks first.
11614 -- Even when evaluation is not possible, we may be able to simplify the
11615 -- conversion or its expression. This needs to be done before applying
11616 -- checks, since otherwise the checks may use the original expression
11617 -- and defeat the simplifications. This is specifically the case for
11618 -- elimination of the floating-point Truncation attribute in
11619 -- float-to-int conversions.
11623 -- If after evaluation we still have a type conversion, then we may need
11624 -- to apply checks required for a subtype conversion.
11626 -- Skip these type conversion checks if universal fixed operands
11627 -- are involved, since range checks are handled separately for
11628 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
11634 then
11638 -- Issue warning for conversion of simple object to its own type. We
11639 -- have to test the original nodes, since they may have been rewritten
11640 -- by various optimizations.
11644 -- Here we test for a redundant conversion if the warning mode is
11645 -- active (and was not locally reset), and we have a type conversion
11646 -- from source not appearing in a generic instance.
11648 if Test_Redundant
11651 and then not In_Instance
11652 then
11656 -- If the node is part of a larger expression, the Target_Type
11657 -- may not be the original type of the node if the context is a
11658 -- condition. Recover original type to see if conversion is needed.
11662 then
11666 -- If we have an entity name, then give the warning if the entity
11667 -- is the right type, or if it is a loop parameter covered by the
11668 -- original type (that's needed because loop parameters have an
11669 -- odd subtype coming from the bounds).
11673 and then
11675 or else
11679 -- If not an entity, then type of expression must match
11682 then
11683 -- One more check, do not give warning if the analyzed conversion
11684 -- has an expression with non-static bounds, and the bounds of the
11685 -- target are static. This avoids junk warnings in cases where the
11686 -- conversion is necessary to establish staticness, for example in
11687 -- a case statement.
11691 then
11694 -- Finally, if this type conversion occurs in a context requiring
11695 -- a prefix, and the expression is a qualified expression then the
11696 -- type conversion is not redundant, since a qualified expression
11697 -- is not a prefix, whereas a type conversion is. For example, "X
11698 -- := T'(Funx(...)).Y;" is illegal because a selected component
11699 -- requires a prefix, but a type conversion makes it legal: "X :=
11700 -- T(T'(Funx(...))).Y;"
11702 -- In Ada 2012, a qualified expression is a name, so this idiom is
11703 -- no longer needed, but we still suppress the warning because it
11704 -- seems unfriendly for warnings to pop up when you switch to the
11705 -- newer language version.
11709 | N_Indexed_Component
11710 | N_Selected_Component
11711 | N_Slice
11712 | N_Explicit_Dereference
11713 then
11716 -- Never warn on conversion to Long_Long_Integer'Base since
11717 -- that is most likely an artifact of the extended overflow
11718 -- checking and comes from complex expanded code.
11723 -- Here we give the redundant conversion warning. If it is an
11724 -- entity, give the name of the entity in the message. If not,
11725 -- just mention the expression.
11727 else
11730 Error_Msg_NE -- CODEFIX
11733 else
11734 Error_Msg_NE
11742 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
11743 -- No need to perform any interface conversion if the type of the
11744 -- expression coincides with the target type.
11747 and then Expander_Active
11749 then
11750 declare
11754 begin
11755 -- If the type of the operand is a limited view, use nonlimited
11756 -- view when available. If it is a class-wide type, recover the
11757 -- class-wide type of the nonlimited view.
11761 then
11766 -- It seems that Non_Limited_View should also be applied for
11767 -- Target when it has a limited view, but that leads to missing
11768 -- error checks on interface conversions further below. ???
11773 -- If the type of the operand is a limited view, use nonlimited
11774 -- view when available. If it is a class-wide type, recover the
11775 -- class-wide type of the nonlimited view.
11779 then
11787 -- If the target type is a limited view, use nonlimited view
11788 -- when available.
11792 then
11800 -- Conversion from interface type
11802 -- It seems that it would be better for the error checks below
11803 -- to be performed as part of Validate_Conversion (and maybe some
11804 -- of the error checks above could be moved as well?). ???
11808 -- Ada 2005 (AI-217): Handle entities from limited views
11812 Error_Msg_NE -- CODEFIX
11815 Error_Msg_N
11817 N);
11820 and then not
11823 then
11825 Error_Msg_NE -- CODEFIX
11828 Error_Msg_N
11830 N);
11832 else
11836 -- Conversion to interface type
11840 -- Handle subtypes
11847 or else Interface_Present_In_Ancestor
11850 then
11852 else
11855 Error_Msg_N
11863 -- Ada 2012: Once the type conversion is resolved, check whether the
11864 -- operand statisfies a static predicate of the target subtype, if any.
11865 -- In the static expression case, a predicate check failure is an error.
11868 Check_Expression_Against_Static_Predicate
11872 -- If at this stage we have a fixed point to integer conversion, make
11873 -- sure that the Do_Range_Check flag is set which is not always done
11874 -- by exp_fixd.adb.
11881 then
11885 -- Generating C code a type conversion of an access to constrained
11886 -- array type to access to unconstrained array type involves building
11887 -- a fat pointer which in general cannot be generated on the fly. We
11888 -- remove side effects in order to store the result of the conversion
11889 -- into a temporary.
11891 if Modify_Tree_For_C
11898 then
11903 ----------------------
11904 -- Resolve_Unary_Op --
11905 ----------------------
11914 begin
11915 -- Deal with intrinsic unary operators
11921 then
11926 -- Deal with universal cases
11929 or else
11931 then
11938 -- Generate warning for expressions like abs (x mod 2)
11940 if Warn_On_Redundant_Constructs
11942 then
11946 Error_Msg_N -- CODEFIX
11951 -- Deal with reference generation
11958 -- Set overflow checking bit. Much cleverer code needed here eventually
11959 -- and perhaps the Resolve routines should be separated for the various
11960 -- arithmetic operations, since they will need different processing ???
11968 -- Generate warning for expressions like -5 mod 3 for integers. No need
11969 -- to worry in the floating-point case, since parens do not affect the
11970 -- result so there is no point in giving in a warning.
11972 declare
11981 begin
11982 if Warn_On_Questionable_Missing_Parens
11986 then
11989 -- We are looking for cases where the right operand is not
11990 -- parenthesized, and is a binary operator, multiply, divide, or
11991 -- mod. These are the cases where the grouping can affect results.
11995 then
11996 -- For mod, we always give the warning, since the value is
11997 -- affected by the parenthesization (e.g. (-5) mod 315 /=
11998 -- -(5 mod 315)). But for the other cases, the only concern is
11999 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
12000 -- overflows, but (-2) * 64 does not). So we try to give the
12001 -- message only when overflow is possible.
12005 then
12010 else
12016 else
12020 -- Note that the test below is deliberately excluding the
12021 -- largest negative number, since that is a potentially
12022 -- troublesome case (e.g. -2 * x, where the result is the
12023 -- largest negative integer has an overflow with 2 * x).
12030 -- For the multiplication case, the only case we have to worry
12031 -- about is when (-a)*b is exactly the largest negative number
12032 -- so that -(a*b) can cause overflow. This can only happen if
12033 -- a is a power of 2, and more generally if any operand is a
12034 -- constant that is not a power of 2, then the parentheses
12035 -- cannot affect whether overflow occurs. We only bother to
12036 -- test the left most operand
12038 -- Loop looking at left operands for one that has known value
12045 -- Operand value of 0 or 1 skips warning
12050 -- Otherwise check power of 2, if power of 2, warn, if
12051 -- anything else, skip warning.
12053 else
12057 else
12066 -- Keep looking at left operands
12071 -- For rem or "/" we can only have a problematic situation
12072 -- if the divisor has a value of minus one or one. Otherwise
12073 -- overflow is impossible (divisor > 1) or we have a case of
12074 -- division by zero in any case.
12079 then
12083 -- If we fall through warning should be issued
12085 -- Shouldn't we test Warn_On_Questionable_Missing_Parens ???
12087 Error_Msg_N
12094 ----------------------------------
12095 -- Resolve_Unchecked_Expression --
12096 ----------------------------------
12098 procedure Resolve_Unchecked_Expression
12101 is
12102 begin
12107 ---------------------------------------
12108 -- Resolve_Unchecked_Type_Conversion --
12109 ---------------------------------------
12111 procedure Resolve_Unchecked_Type_Conversion
12114 is
12120 begin
12121 -- Resolve operand using its own type
12125 -- If the expression is a conversion to universal integer of an
12126 -- an expression with an integer type, then we can eliminate the
12127 -- intermediate conversion to universal integer.
12132 then
12137 -- In an inlined context, the unchecked conversion may be applied
12138 -- to a literal, in which case its type is the type of the context.
12139 -- (In other contexts conversions cannot apply to literals).
12141 if In_Inlined_Body
12145 then
12153 ------------------------------
12154 -- Rewrite_Operator_As_Call --
12155 ------------------------------
12162 begin
12169 New_N :=
12180 ------------------------------
12181 -- Rewrite_Renamed_Operator --
12182 ------------------------------
12184 procedure Rewrite_Renamed_Operator
12188 is
12193 begin
12194 -- Do not perform this transformation within a pre/postcondition,
12195 -- because the expression will be reanalyzed, and the transformation
12196 -- might affect the visibility of the operator, e.g. in an instance.
12197 -- Note that fully analyzed and expanded pre/postconditions appear as
12198 -- pragma Check equivalents.
12204 -- Likewise when an expression function is being preanalyzed, since the
12205 -- expression will be reanalyzed as part of the generated body.
12208 declare
12210 begin
12213 N_Expression_Function
12214 then
12220 -- Rewrite the operator node using the real operator, not its renaming.
12221 -- Exclude user-defined intrinsic operations of the same name, which are
12222 -- treated separately and rewritten as calls.
12231 -- Indicate that both the original entity and its renaming are
12232 -- referenced at this point.
12243 -- If the context type is private, add the appropriate conversions so
12244 -- that the operator is applied to the full view. This is done in the
12245 -- routines that resolve intrinsic operators.
12249 when N_Op_Add
12250 | N_Op_Divide
12251 | N_Op_Expon
12252 | N_Op_Mod
12253 | N_Op_Multiply
12254 | N_Op_Rem
12255 | N_Op_Subtract
12256 =>
12259 when N_Op_Abs
12260 | N_Op_Minus
12261 | N_Op_Plus
12262 =>
12272 -- Operator renames a user-defined operator of the same name. Use the
12273 -- original operator in the node, which is the one Gigi knows about.
12280 -----------------------
12281 -- Set_Slice_Subtype --
12282 -----------------------
12284 -- Build an implicit subtype declaration to represent the type delivered by
12285 -- the slice. This is an abbreviated version of an array subtype. We define
12286 -- an index subtype for the slice, using either the subtype name or the
12287 -- discrete range of the slice. To be consistent with index usage elsewhere
12288 -- we create a list header to hold the single index. This list is not
12289 -- otherwise attached to the syntax tree.
12300 begin
12306 else
12307 -- We force the evaluation of a range. This is definitely needed in
12308 -- the renamed case, and seems safer to do unconditionally. Note in
12309 -- any case that since we will create and insert an Itype referring
12310 -- to this range, we must make sure any side effect removal actions
12311 -- are inserted before the Itype definition.
12317 -- If the discrete range is given by a subtype indication, the
12318 -- type of the slice is the base of the subtype mark.
12321 declare
12323 begin
12332 -- Take a new copy of Drange (where bounds have been rewritten to
12333 -- reference side-effect-free names). Using a separate tree ensures
12334 -- that further expansion (e.g. while rewriting a slice assignment
12335 -- into a FOR loop) does not attempt to remove side effects on the
12336 -- bounds again (which would cause the bounds in the index subtype
12337 -- definition to refer to temporaries before they are defined) (the
12338 -- reason is that some names are considered side effect free here
12339 -- for the subtype, but not in the context of a loop iteration
12340 -- scheme).
12362 -- The Etype of the existing Slice node is reset to this slice subtype.
12363 -- Its bounds are obtained from its first index.
12367 -- For bit-packed slice subtypes, freeze immediately (except in the case
12368 -- of being in a "spec expression" where we never freeze when we first
12369 -- see the expression).
12374 -- For all other cases insert an itype reference in the slice's actions
12375 -- so that the itype is frozen at the proper place in the tree (i.e. at
12376 -- the point where actions for the slice are analyzed). Note that this
12377 -- is different from freezing the itype immediately, which might be
12378 -- premature (e.g. if the slice is within a transient scope). This needs
12379 -- to be done only if expansion is enabled.
12386 --------------------------------
12387 -- Set_String_Literal_Subtype --
12388 --------------------------------
12396 begin
12408 -- The low bound is set from the low bound of the corresponding index
12409 -- type. Note that we do not store the high bound in the string literal
12410 -- subtype, but it can be deduced if necessary from the length and the
12411 -- low bound.
12416 -- If the lower bound is not static we create a range for the string
12417 -- literal, using the index type and the known length of the literal.
12418 -- If the length is 1, then the upper bound is set to a mere copy of
12419 -- the lower bound; or else, if the index type is a signed integer,
12420 -- then the upper bound is computed as Low_Bound + L - 1; otherwise,
12421 -- the upper bound is computed as T'Val (T'Pos (Low_Bound) + L - 1).
12423 else
12424 declare
12434 begin
12439 High_Bound :=
12444 else
12445 High_Bound :=
12448 Prefix =>
12452 Left_Opnd =>
12455 Prefix =>
12457 Expressions =>
12459 Right_Opnd =>
12464 Set_String_Literal_Low_Bound
12467 else
12468 -- If the index type is an enumeration type, build bounds
12469 -- expression with attributes.
12471 Set_String_Literal_Low_Bound
12475 Prefix =>
12479 Analyze_And_Resolve
12482 -- Build bona fide subtype for the string, and wrap it in an
12483 -- unchecked conversion, because the back end expects the
12484 -- String_Literal_Subtype to have a static lower bound.
12486 Index_Subtype :=
12493 -- In this context, the Index_Type may already have a constraint,
12494 -- so use common base type on string subtype. The base type may
12495 -- be used when generating attributes of the string, for example
12496 -- in the context of a slice assignment.
12521 ------------------------------
12522 -- Simplify_Type_Conversion --
12523 ------------------------------
12526 begin
12528 declare
12533 begin
12534 -- Special processing if the conversion is the expression of a
12535 -- Rounding or Truncation attribute reference. In this case we
12536 -- replace:
12538 -- ityp (ftyp'Rounding (x)) or ityp (ftyp'Truncation (x))
12540 -- by
12542 -- ityp (x)
12544 -- with the Float_Truncate flag set to False or True respectively,
12545 -- which is more efficient. We reuse Rounding for Machine_Rounding
12546 -- as System.Fat_Gen, which is a permissible behavior.
12549 and then
12555 | Name_Machine_Rounding
12556 | Name_Truncation
12557 then
12558 declare
12561 begin
12567 -- Special processing for the conversion of an integer literal to
12568 -- a dynamic type: we first convert the literal to the root type
12569 -- and then convert the result to the target type, the goal being
12570 -- to avoid doing range checks in universal integer.
12576 then
12580 -- If the expression is a conversion to universal integer of an
12581 -- an expression with an integer type, then we can eliminate the
12582 -- intermediate conversion to universal integer.
12587 then
12595 -----------------------------
12596 -- Unique_Fixed_Point_Type --
12597 -----------------------------
12601 -- Give error messages for true ambiguity. Messages are posted on node
12602 -- N, and entities T1, T2 are the possible interpretations.
12604 -----------------------
12605 -- Fixed_Point_Error --
12606 -----------------------
12609 begin
12615 -- Local variables
12623 -- Start of processing for Unique_Fixed_Point_Type
12625 begin
12626 -- The operations on Duration are visible, so Duration is always a
12627 -- possible interpretation.
12631 -- Look for fixed-point types in enclosing scopes
12640 then
12644 else
12655 -- Look for visible fixed type declarations in the context
12666 then
12670 else
12685 else
12686 -- When the context is a type conversion, issue the warning on the
12687 -- expression of the conversion because it is the actual operation.
12691 else
12695 Error_Msg_NE
12702 ----------------------
12703 -- Valid_Conversion --
12704 ----------------------
12706 function Valid_Conversion
12711 is
12716 function Conversion_Check
12719 -- Little routine to post Msg if Valid is False, returns Valid value
12722 -- If Report_Errs, then calls Errout.Error_Msg_N with its arguments
12724 procedure Conversion_Error_NE
12728 -- If Report_Errs, then calls Errout.Error_Msg_NE with its arguments
12731 -- Return True if expression is within an instance but is not in one of
12732 -- the actuals of the instantiation. Type conversions within an instance
12733 -- are not rechecked because type visbility may lead to spurious errors,
12734 -- but conversions in an actual for a formal object must be checked.
12736 function Is_Discrim_Of_Bad_Access_Conversion_Argument
12738 -- Implicit anonymous-to-named access type conversions are not allowed
12739 -- if the "statically deeper than" relationship does not apply to the
12740 -- type of the conversion operand. See RM 8.6(28.1) and AARM 8.6(28.d).
12741 -- We deal with most such cases elsewhere so that we can emit more
12742 -- specific error messages (e.g., if the operand is an access parameter
12743 -- or a saooaaat (stand-alone object of an anonymous access type)), but
12744 -- here is where we catch the case where the operand is an access
12745 -- discriminant selected from a dereference of another such "bad"
12746 -- conversion argument.
12748 function Valid_Tagged_Conversion
12751 -- Specifically test for validity of tagged conversions
12754 -- Check index and component conformance, and accessibility levels if
12755 -- the component types are anonymous access types (Ada 2005).
12757 ----------------------
12758 -- Conversion_Check --
12759 ----------------------
12761 function Conversion_Check
12764 is
12765 begin
12766 if not Valid
12768 -- A generic unit has already been analyzed and we have verified
12769 -- that a particular conversion is OK in that context. Since the
12770 -- instance is reanalyzed without relying on the relationships
12771 -- established during the analysis of the generic, it is possible
12772 -- to end up with inconsistent views of private types. Do not emit
12773 -- the error message in such cases. The rest of the machinery in
12774 -- Valid_Conversion still ensures the proper compatibility of
12775 -- target and operand types.
12777 and then not In_Instance_Code
12778 then
12785 ------------------------
12786 -- Conversion_Error_N --
12787 ------------------------
12790 begin
12796 -------------------------
12797 -- Conversion_Error_NE --
12798 -------------------------
12800 procedure Conversion_Error_NE
12804 is
12805 begin
12811 ----------------------
12812 -- In_Instance_Code --
12813 ----------------------
12818 begin
12822 else
12826 -- The expression is part of an actual object if it appears in
12827 -- the generated object declaration in the instance.
12831 then
12834 else
12835 exit when
12844 -- Otherwise the expression appears within the instantiated unit
12850 --------------------------------------------------
12851 -- Is_Discrim_Of_Bad_Access_Conversion_Argument --
12852 --------------------------------------------------
12854 function Is_Discrim_Of_Bad_Access_Conversion_Argument
12856 is
12862 begin
12874 -- return False if Expr not of form <prefix>.all.Some_Component
12878 then
12879 -- conditional expressions, declare expressions ???
12886 -- The "statically deeper relationship" does not apply
12887 -- to generic formal access types, so a prefix of such
12888 -- a type is a "bad" prefix.
12893 -- The "statically deeper relationship" does apply to
12894 -- any other named access type.
12903 -- The "statically deeper relationship" applies to some
12904 -- anonymous access types and not to others. Return
12905 -- True for the cases where it does not apply. Also check
12906 -- recursively for the
12907 -- <prefix>.all.Access_Discrim.all.Access_Discrim case,
12908 -- where the correct result depends on <prefix>.
12911 N_Procedure_Specification | -- access parameter
12912 N_Function_Specification | -- access parameter
12913 N_Object_Declaration -- saooaaat
12917 ----------------------------
12918 -- Valid_Array_Conversion --
12919 ----------------------------
12936 begin
12937 -- Error if wrong number of dimensions
12939 if
12941 then
12942 Conversion_Error_N
12946 -- Number of dimensions matches
12948 else
12949 -- Loop through indexes of the two arrays
12957 -- Error if index types are incompatible
12963 then
12964 Conversion_Error_N
12966 Operand);
12974 -- If component types have same base type, all set
12979 -- Here if base types of components are not the same. The only
12980 -- time this is allowed is if we have anonymous access types.
12982 -- The conversion of arrays of anonymous access types can lead
12983 -- to dangling pointers. AI-392 formalizes the accessibility
12984 -- checks that must be applied to such conversions to prevent
12985 -- out-of-scope references.
12988 E_Anonymous_Access_Type
12989 | E_Anonymous_Access_Subprogram_Type
12991 and then
12993 then
12996 then
12999 Conversion_Error_N
13009 -- Conversion not allowed because of accessibility levels
13011 else
13012 Conversion_Error_N
13018 else
13022 -- All other cases where component base types do not match
13024 else
13025 Conversion_Error_N
13027 Operand);
13031 -- Check that component subtypes statically match. For numeric
13032 -- types this means that both must be either constrained or
13033 -- unconstrained. For enumeration types the bounds must match.
13034 -- All of this is checked in Subtypes_Statically_Match.
13036 if not Subtypes_Statically_Match
13038 then
13039 Conversion_Error_N
13048 -----------------------------
13049 -- Valid_Tagged_Conversion --
13050 -----------------------------
13052 function Valid_Tagged_Conversion
13055 is
13056 begin
13057 -- Upward conversions are allowed (RM 4.6(22))
13061 then
13064 -- Downward conversion are allowed if the operand is class-wide
13065 -- (RM 4.6(23)).
13069 then
13074 then
13075 return
13079 -- Ada 2005 (AI-251): The conversion to/from interface types is
13080 -- always valid. The types involved may be class-wide (sub)types.
13084 then
13087 -- If the operand is a class-wide type obtained through a limited_
13088 -- with clause, and the context includes the nonlimited view, use
13089 -- it to determine whether the conversion is legal.
13095 then
13100 then
13103 else
13104 Conversion_Error_NE
13111 -- Start of processing for Valid_Conversion
13113 begin
13117 declare
13125 begin
13126 -- Remove procedure calls, which syntactically cannot appear in
13127 -- this context, but which cannot be removed by type checking,
13128 -- because the context does not impose a type.
13130 -- The node may be labelled overloaded, but still contain only one
13131 -- interpretation because others were discarded earlier. If this
13132 -- is the case, retain the single interpretation if legal.
13140 then
13141 -- More than one candidate interpretation is available
13149 -- When compiling for a system where Address is of a visible
13150 -- integer type, spurious ambiguities can be produced when
13151 -- arithmetic operations have a literal operand and return
13152 -- System.Address or a descendant of it. These ambiguities
13153 -- are usually resolved by the context, but for conversions
13154 -- there is no context type and the removal of the spurious
13155 -- operations must be done explicitly here.
13157 if not Address_Is_Private
13159 then
13184 Conversion_Error_N
13187 -- If the interpretation involves a standard operator, use
13188 -- the location of the type, which may be user-defined.
13192 else
13196 Conversion_Error_N -- CODEFIX
13201 else
13205 Conversion_Error_N -- CODEFIX
13217 -- Deal with conversion of integer type to address if the pragma
13218 -- Allow_Integer_Address is in effect. We convert the conversion to
13219 -- an unchecked conversion in this case and we are all done.
13227 -- If we are within a child unit, check whether the type of the
13228 -- expression has an ancestor in a parent unit, in which case it
13229 -- belongs to its derivation class even if the ancestor is private.
13230 -- See RM 7.3.1 (5.2/3).
13234 -- Numeric types
13238 -- A universal fixed expression can be converted to any numeric type
13243 -- Also no need to check when in an instance or inlined body, because
13244 -- the legality has been established when the template was analyzed.
13245 -- Furthermore, numeric conversions may occur where only a private
13246 -- view of the operand type is visible at the instantiation point.
13247 -- This results in a spurious error if we check that the operand type
13248 -- is a numeric type.
13250 -- Note: in a previous version of this unit, the following tests were
13251 -- applied only for generated code (Comes_From_Source set to False),
13252 -- but in fact the test is required for source code as well, since
13253 -- this situation can arise in source code.
13258 -- Otherwise we need the conversion check
13260 else
13261 return Conversion_Check
13263 or else
13269 -- Array types
13275 then
13276 Conversion_Error_N
13280 else
13284 -- Ada 2005 (AI-251): Internally generated conversions of access to
13285 -- interface types added to force the displacement of the pointer to
13286 -- reference the corresponding dispatch table.
13291 then
13294 -- Ada 2005 (AI-251): Anonymous access types where target references an
13295 -- interface type.
13299 E_General_Access_Type | E_Anonymous_Access_Type
13301 then
13302 -- Check the static accessibility rule of 4.6(17). Note that the
13303 -- check is not enforced when within an instance body, since the
13304 -- RM requires such cases to be caught at run time.
13306 -- If the operand is a rewriting of an allocator no check is needed
13307 -- because there are no accessibility issues.
13315 then
13316 -- In an instance, this is a run-time check, but one we know
13317 -- will fail, so generate an appropriate warning. The raise
13318 -- will be generated by Expand_N_Type_Conversion.
13322 Conversion_Error_N
13324 Operand);
13327 else
13328 Conversion_Error_N
13330 Operand);
13334 -- Special accessibility checks are needed in the case of access
13335 -- discriminants declared for a limited type.
13339 then
13340 -- When the operand is a selected access discriminant the check
13341 -- needs to be made against the level of the object denoted by
13342 -- the prefix of the selected name (Object_Access_Level handles
13343 -- checking the prefix of the operand for this case).
13348 then
13349 -- In an instance, this is a run-time check, but one we know
13350 -- will fail, so generate an appropriate warning. The raise
13351 -- will be generated by Expand_N_Type_Conversion.
13355 Conversion_Error_N
13360 -- Real error if not in instance body
13362 else
13363 Conversion_Error_N
13370 -- The case of a reference to an access discriminant from
13371 -- within a limited type declaration (which will appear as
13372 -- a discriminal) is always illegal because the level of the
13373 -- discriminant is considered to be deeper than any (nameable)
13374 -- access type.
13378 and then
13381 then
13382 Conversion_Error_N
13384 Operand);
13392 -- General and anonymous access types
13395 E_General_Access_Type | E_Anonymous_Access_Type
13396 and then
13397 Conversion_Check
13399 and then
13401 E_Access_Subprogram_Type |
13402 E_Access_Protected_Subprogram_Type,
13404 then
13407 then
13408 Conversion_Error_N
13413 -- Check the static accessibility rule of 4.6(17). Note that the
13414 -- check is not enforced when within an instance body, since the RM
13415 -- requires such cases to be caught at run time.
13420 N_Object_Declaration
13421 then
13422 -- Ada 2012 (AI05-0149): Perform legality checking on implicit
13423 -- conversions from an anonymous access type to a named general
13424 -- access type. Such conversions are not allowed in the case of
13425 -- access parameters and stand-alone objects of an anonymous
13426 -- access type. The implicit conversion case is recognized by
13427 -- testing that Comes_From_Source is False and that it's been
13428 -- rewritten. The Comes_From_Source test isn't sufficient because
13429 -- nodes in inlined calls to predefined library routines can have
13430 -- Comes_From_Source set to False. (Is there a better way to test
13431 -- for implicit conversions???).
13432 --
13433 -- Do not treat a rewritten 'Old attribute reference like other
13434 -- rewrite substitutions. This makes a difference, for example,
13435 -- in the case where we are generating the expansion of a
13436 -- membership test of the form
13437 -- Saooaaat'Old in Named_Access_Type
13438 -- because in this case Valid_Conversion needs to return True
13439 -- (otherwise the expansion will be False - see the call site
13440 -- in exp_ch4.adb).
13448 then
13451 -- Implicit conversions aren't allowed for objects of an
13452 -- anonymous access type, since such objects have nonstatic
13453 -- levels in Ada 2012.
13456 N_Object_Declaration
13457 then
13458 Conversion_Error_N
13463 -- Implicit conversions aren't allowed for anonymous access
13464 -- parameters. We exclude anonymous access results as well
13465 -- as universal_access "=".
13469 N_Function_Specification |
13470 N_Procedure_Specification
13472 then
13473 Conversion_Error_N
13478 -- Detect access discriminant values that are illegal
13479 -- implicit anonymous-to-named access conversion operands.
13482 then
13483 Conversion_Error_N
13488 -- In other cases, the level of the operand's type must be
13489 -- statically less deep than that of the target type, else
13490 -- implicit conversion is disallowed (by RM12-8.6(27.1/3)).
13494 then
13495 Conversion_Error_N
13502 -- Check if the operand is deeper than the target type, taking
13503 -- care to avoid the case where we are converting a result of a
13504 -- function returning an anonymous access type since the "master
13505 -- of the call" would be target type of the conversion unless
13506 -- the target type is anonymous access as well - see RM 3.10.2
13507 -- (10.3/3).
13512 N_Function_Specification
13514 Anonymous_Access_Kind)
13515 then
13516 -- In an instance, this is a run-time check, but one we know
13517 -- will fail, so generate an appropriate warning. The raise
13518 -- will be generated by Expand_N_Type_Conversion.
13522 Conversion_Error_N
13524 Operand);
13527 -- If not in an instance body, this is a real error
13529 else
13530 -- Avoid generation of spurious error message
13533 Conversion_Error_N
13535 Operand);
13541 -- Special accessibility checks are needed in the case of access
13542 -- discriminants declared for a limited type.
13546 then
13547 -- When the operand is a selected access discriminant the check
13548 -- needs to be made against the level of the object denoted by
13549 -- the prefix of the selected name (Object_Access_Level handles
13550 -- checking the prefix of the operand for this case).
13555 then
13556 -- In an instance, this is a run-time check, but one we know
13557 -- will fail, so generate an appropriate warning. The raise
13558 -- will be generated by Expand_N_Type_Conversion.
13562 Conversion_Error_N
13567 -- If not in an instance body, this is a real error
13569 else
13570 Conversion_Error_N
13577 -- The case of a reference to an access discriminant from
13578 -- within a limited type declaration (which will appear as
13579 -- a discriminal) is always illegal because the level of the
13580 -- discriminant is considered to be deeper than any (nameable)
13581 -- access type.
13584 and then
13587 then
13588 Conversion_Error_N
13590 Operand);
13596 -- In the presence of limited_with clauses we have to use nonlimited
13597 -- views, if available.
13601 -- Helper function to handle limited views
13603 --------------------------
13604 -- Full_Designated_Type --
13605 --------------------------
13610 begin
13611 -- Handle the limited view of a type
13615 then
13617 else
13622 -- Local Declarations
13630 -- Start of processing for Check_Limited
13632 begin
13636 else
13638 Conversion_Error_NE
13643 -- Ada 2005 AI-384: legality rule is symmetric in both
13644 -- designated types. The conversion is legal (with possible
13645 -- constraint check) if either designated type is
13646 -- unconstrained.
13649 or else
13651 and then
13654 then
13655 -- Special case, if Value_Size has been used to make the
13656 -- sizes different, the conversion is not allowed even
13657 -- though the subtypes statically match.
13662 then
13663 Conversion_Error_NE
13666 Conversion_Error_NE
13671 -- Normal case where conversion is allowed
13673 else
13677 else
13678 Error_Msg_NE
13686 -- Access to subprogram types. If the operand is an access parameter,
13687 -- the type has a deeper accessibility that any master, and cannot be
13688 -- assigned. We must make an exception if the conversion is part of an
13689 -- assignment and the target is the return object of an extended return
13690 -- statement, because in that case the accessibility check takes place
13691 -- after the return.
13695 -- Note: this test of Opnd_Type is there to prevent entering this
13696 -- branch in the case of a remote access to subprogram type, which
13697 -- is internally represented as an E_Record_Type.
13700 then
13704 and then
13708 then
13709 Conversion_Error_N
13711 Operand);
13712 Conversion_Error_N
13715 Operand);
13717 Error_Msg_NE
13722 -- Check that the designated types are subtype conformant
13728 -- Check the static accessibility rule of 4.6(20)
13732 then
13733 Conversion_Error_N
13735 Operand);
13737 -- Check that if the operand type is declared in a generic body,
13738 -- then the target type must be declared within that same body
13739 -- (enforces last sentence of 4.6(20)).
13742 declare
13748 begin
13755 Conversion_Error_N
13764 -- Remote access to subprogram types
13768 then
13769 -- It is valid to convert from one RAS type to another provided
13770 -- that their specification statically match.
13772 -- Note: at this point, remote access to subprogram types have been
13773 -- expanded to their E_Record_Type representation, and we need to
13774 -- go back to the original access type definition using the
13775 -- Corresponding_Remote_Type attribute in order to check that the
13776 -- designated profiles match.
13781 Check_Subtype_Conformant
13784 Old_Id =>
13786 Err_Loc =>
13787 N);
13790 -- If it was legal in the generic, it's legal in the instance
13795 -- If both are tagged types, check legality of view conversions
13798 and then
13800 then
13803 -- Types derived from the same root type are convertible
13808 -- In an instance or an inlined body, there may be inconsistent views of
13809 -- the same type, or of types derived from a common root.
13812 and then
13815 then
13818 -- Special check for common access type error case
13822 then
13824 Conversion_Error_NE -- CODEFIX
13828 -- Here we have a real conversion error
13830 else
13831 -- Check for missing regular with_clause when only a limited view of
13832 -- target is available.
13835 Conversion_Error_NE
13838 Conversion_Error_NE
13843 and then In_Package_Body
13844 then
13845 Conversion_Error_NE
13847 Conversion_Error_NE
13851 else
13852 Conversion_Error_NE