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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) 1992-2014, Free Software Foundation, Inc. --
10 -- --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
20 -- --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
23 -- --
24 ------------------------------------------------------------------------------
84 -----------------------
85 -- Local Subprograms --
86 -----------------------
88 -- Second pass (top-down) type checking and overload resolution procedures
89 -- Typ is the type required by context. These procedures propagate the type
90 -- information recursively to the descendants of N. If the node is not
91 -- overloaded, its Etype is established in the first pass. If overloaded,
92 -- the Resolve routines set the correct type. For arith. operators, the
93 -- Etype is the base type of the context.
95 -- Note that Resolve_Attribute is separated off in Sem_Attr
98 -- Enforce the restrictions on the use of discriminants when constraining
99 -- a component of a discriminated type (record or concurrent type).
102 -- Given a node for an operator associated with type T, check that
103 -- the operator is visible. Operators all of whose operands are
104 -- universal must be checked for visibility during resolution
105 -- because their type is not determinable based on their operands.
107 procedure Check_Fully_Declared_Prefix
110 -- Check that the type of the prefix of a dereference is not incomplete
113 -- Determine whether node Ghost_Ref appears within a Ghost-friendly context
114 -- where Ghost entity Ghost_Id can safely reside.
117 -- Given a call node, N, 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 -- If the type of the object being initialized uses the secondary stack
124 -- directly or indirectly, create a transient scope for the call to the
125 -- init proc. This is because we do not create transient scopes for the
126 -- initialization of individual components within the init proc itself.
127 -- Could be optimized away perhaps?
130 -- N is the node for a logical operator. If the operator is predefined, and
131 -- the root type of the operands is Standard.Boolean, then a check is made
132 -- for restriction No_Direct_Boolean_Operators. This procedure also handles
133 -- the style check for Style_Check_Boolean_And_Or.
136 -- N is either an indexed component or a selected component. This function
137 -- returns true if the prefix refers to an object that has an address
138 -- clause (the case in which we may want to issue a warning).
141 -- Determine whether E is an access type declared by an access declaration,
142 -- and not an (anonymous) allocator type.
145 -- Utility to check whether the entity for an operator is a predefined
146 -- operator, in which case the expression is left as an operator in the
147 -- tree (else it is rewritten into a call). An instance of an intrinsic
148 -- conversion operation may be given an operator name, but is not treated
149 -- like an operator. Note that an operator that is an imported back-end
150 -- builtin has convention Intrinsic, but is expected to be rewritten into
151 -- a call, so such an operator is not treated as predefined by this
152 -- predicate.
155 -- If a default expression in entry call N depends on the discriminants
156 -- of the task, it must be replaced with a reference to the discriminant
157 -- of the task being called.
159 procedure Resolve_Op_Concat_Arg
164 -- Internal procedure for Resolve_Op_Concat to resolve one operand of
165 -- concatenation operator. The operand is either of the array type or of
166 -- the component type. If the operand is an aggregate, and the component
167 -- type is composite, this is ambiguous if component type has aggregates.
170 -- Does the first part of the work of Resolve_Op_Concat
173 -- Does the "rest" of the work of Resolve_Op_Concat, after the left operand
174 -- has been resolved. See Resolve_Op_Concat for details.
212 function Operator_Kind
215 -- Utility to map the name of an operator into the corresponding Node. Used
216 -- by other node rewriting procedures.
219 -- Resolve actuals of call, and add default expressions for missing ones.
220 -- N is the Node_Id for the subprogram call, and Nam is the entity of the
221 -- called subprogram.
224 -- Called from Resolve_Call, when the prefix denotes an entry or element
225 -- of entry family. Actuals are resolved as for subprograms, and the node
226 -- is rebuilt as an entry call. Also called for protected operations. Typ
227 -- is the context type, which is used when the operation is a protected
228 -- function with no arguments, and the return value is indexed.
231 -- A call to a user-defined intrinsic operator is rewritten as a call to
232 -- the corresponding predefined operator, with suitable conversions. Note
233 -- that this applies only for intrinsic operators that denote predefined
234 -- operators, not ones that are intrinsic imports of back-end builtins.
237 -- Ditto, for arithmetic unary operators
240 -- If an operator node resolves to a call to a user-defined operator,
241 -- rewrite the node as a function call.
243 procedure Make_Call_Into_Operator
247 -- Inverse transformation: if an operator is given in functional notation,
248 -- then after resolving the node, transform into an operator node, so
249 -- that operands are resolved properly. Recall that predefined operators
250 -- do not have a full signature and special resolution rules apply.
252 procedure Rewrite_Renamed_Operator
256 -- An operator can rename another, e.g. in an instantiation. In that
257 -- case, the proper operator node must be constructed and resolved.
260 -- The String_Literal_Subtype is built for all strings that are not
261 -- operands of a static concatenation operation. If the argument is
262 -- not a N_String_Literal node, then the call has no effect.
265 -- Build subtype of array type, with the range specified by the slice
268 -- Called after N has been resolved and evaluated, but before range checks
269 -- have been applied. Currently simplifies a combination of floating-point
270 -- to integer conversion and Rounding or Truncation attribute.
273 -- A universal_fixed expression in an universal context is unambiguous if
274 -- there is only one applicable fixed point type. Determining whether there
275 -- is only one requires a search over all visible entities, and happens
276 -- only in very pathological cases (see 6115-006).
278 -------------------------
279 -- Ambiguous_Character --
280 -------------------------
285 begin
289 -- First the ones in Standard
294 -- Include Wide_Wide_Character in Ada 2005 mode
300 -- Now any other types that match
310 -------------------------
311 -- Analyze_And_Resolve --
312 -------------------------
315 begin
321 begin
326 -- Versions with check(s) suppressed
328 procedure Analyze_And_Resolve
332 is
335 begin
337 declare
339 begin
345 else
346 declare
348 begin
356 and then Scope_Is_Transient
357 then
358 -- This can only happen if a transient scope was created for an inner
359 -- expression, which will be removed upon completion of the analysis
360 -- of an enclosing construct. The transient scope must have the
361 -- suppress status of the enclosing environment, not of this Analyze
362 -- call.
365 Scope_Suppress;
369 procedure Analyze_And_Resolve
372 is
375 begin
377 declare
379 begin
385 else
386 declare
388 begin
397 Scope_Suppress;
401 ----------------------------
402 -- Check_Discriminant_Use --
403 ----------------------------
411 begin
412 -- Any use in a spec-expression is legal
419 -- Discriminant cannot be used to constrain a scalar type
426 then
431 -- The following check catches the unusual case where a
432 -- discriminant appears within an index constraint that is part of
433 -- a larger expression within a constraint on a component, e.g. "C
434 -- : Int range 1 .. F (new A(1 .. D))". For now we only check case
435 -- of record components, and note that a similar check should also
436 -- apply in the case of discriminant constraints below. ???
438 -- Note that the check for N_Subtype_Declaration below is to
439 -- detect the valid use of discriminants in the constraints of a
440 -- subtype declaration when this subtype declaration appears
441 -- inside the scope of a record type (which is syntactically
442 -- illegal, but which may be created as part of derived type
443 -- processing for records). See Sem_Ch3.Build_Derived_Record_Type
444 -- for more info.
448 and then not
450 and then
452 N_Subtype_Declaration)
454 then
455 Error_Msg_N
460 -- Detect a common error:
462 -- type R (D : Positive := 100) is record
463 -- Name : String (1 .. D);
464 -- end record;
466 -- The default value causes an object of type R to be allocated
467 -- with room for Positive'Last characters. The RM does not mandate
468 -- the allocation of the maximum size, but that is what GNAT does
469 -- so we should warn the programmer that there is a problem.
478 -- Return True if type T has a large enough range that any
479 -- array whose index type covered the whole range of the type
480 -- would likely raise Storage_Error.
482 ------------------------
483 -- Large_Storage_Type --
484 ------------------------
487 begin
488 -- The type is considered large if its bounds are known at
489 -- compile time and if it requires at least as many bits as
490 -- a Positive to store the possible values.
494 and then
499 -- Start of processing for Check_Large
501 begin
502 -- Check that the Disc has a large range
508 -- If the enclosing type is limited, we allocate only the
509 -- default value, not the maximum, and there is no need for
510 -- a warning.
516 -- Check that it is the high bound
520 then
524 -- Check the array allows a large range at this bound. First
525 -- find the array
539 -- Next, find the dimension
547 loop
556 -- Now, check the dimension has a large range
562 -- Warn about the danger
564 Error_Msg_N
574 -- Legal case is in index or discriminant constraint
577 N_Discriminant_Association)
578 then
580 Error_Msg_N
585 then
586 Error_Msg_N
592 -- Otherwise, context is an expression. It should not be within (i.e. a
593 -- subexpression of) a constraint for a component.
595 else
599 N_Subtype_Indication,
600 N_Entry_Declaration)
601 loop
607 -- If the discriminant is used in an expression that is a bound of a
608 -- scalar type, an Itype is created and the bounds are attached to
609 -- its range, not to the original subtype indication. Such use is of
610 -- course a double fault.
614 N_Derived_Type_Definition)
617 -- The constraint itself may be given by a subtype indication,
618 -- rather than by a more common discrete range.
621 and then
625 then
626 Error_Msg_N
632 --------------------------------
633 -- Check_For_Visible_Operator --
634 --------------------------------
637 begin
639 Error_Msg_NE -- CODEFIX
641 Error_Msg_N -- CODEFIX
646 ----------------------------------
647 -- Check_Fully_Declared_Prefix --
648 ----------------------------------
650 procedure Check_Fully_Declared_Prefix
653 is
654 begin
655 -- Check that the designated type of the prefix of a dereference is
656 -- not an incomplete type. This cannot be done unconditionally, because
657 -- dereferences of private types are legal in default expressions. This
658 -- case is taken care of in Check_Fully_Declared, called below. There
659 -- are also 2005 cases where it is legal for the prefix to be unfrozen.
661 -- This consideration also applies to similar checks for allocators,
662 -- qualified expressions, and type conversions.
664 -- An additional exception concerns other per-object expressions that
665 -- are not directly related to component declarations, in particular
666 -- representation pragmas for tasks. These will be per-object
667 -- expressions if they depend on discriminants or some global entity.
668 -- If the task has access discriminants, the designated type may be
669 -- incomplete at the point the expression is resolved. This resolution
670 -- takes place within the body of the initialization procedure, where
671 -- the discriminant is replaced by its discriminal.
675 then
678 -- Ada 2005 (AI-326): Tagged incomplete types allowed. The wrong usages
679 -- are handled by Analyze_Access_Attribute, Analyze_Assignment,
680 -- Analyze_Object_Renaming, and Freeze_Entity.
686 E_Incomplete_Type
688 then
690 else
695 -------------------------
696 -- Check_Ghost_Context --
697 -------------------------
701 -- Verify that the Ghost policy at the point of declaration of entity Id
702 -- matches the policy at the point of reference. If this is not the case
703 -- emit an error at Err_N.
706 -- Determine whether node Context denotes a Ghost-friendly context where
707 -- a Ghost entity can safely reside.
709 -------------------------
710 -- Is_OK_Ghost_Context --
711 -------------------------
715 -- Determine whether node Decl is a Ghost declaration or appears
716 -- within a Ghost declaration.
718 --------------------------
719 -- Is_Ghost_Declaration --
720 --------------------------
727 begin
728 -- Climb the parent chain looking for an object declaration
733 when N_Abstract_Subprogram_Declaration |
734 N_Exception_Declaration |
735 N_Exception_Renaming_Declaration |
736 N_Full_Type_Declaration |
737 N_Generic_Function_Renaming_Declaration |
738 N_Generic_Package_Declaration |
739 N_Generic_Package_Renaming_Declaration |
740 N_Generic_Procedure_Renaming_Declaration |
741 N_Generic_Subprogram_Declaration |
742 N_Number_Declaration |
743 N_Object_Declaration |
744 N_Object_Renaming_Declaration |
745 N_Package_Declaration |
746 N_Package_Renaming_Declaration |
747 N_Private_Extension_Declaration |
748 N_Private_Type_Declaration |
749 N_Subprogram_Declaration |
750 N_Subprogram_Renaming_Declaration |
751 N_Subtype_Declaration =>
758 -- Special cases
760 -- A reference to a Ghost entity may appear as the default
761 -- expression of a formal parameter of a subprogram body. This
762 -- context must be treated as suitable because the relation
763 -- between the spec and the body has not been established and
764 -- the body is not marked as Ghost yet. The real check was
765 -- performed on the spec.
769 then
772 -- References to Ghost entities may be relocated in internally
773 -- generated bodies.
777 then
780 -- The original context is an expression function that has
781 -- been split into a spec and a body. The context is OK as
782 -- long as the the initial declaration is Ghost.
785 Subp_Decl :=
793 -- Otherwise this is either an internal body or an internal
794 -- completion. Both are OK because the real check was done
795 -- before expansion activities.
800 -- Prevent the search from going too far
812 -- Start of processing for Is_OK_Ghost_Context
814 begin
815 -- The Ghost entity appears within an assertion expression
820 -- The Ghost entity is part of a declaration or its completion
825 -- The Ghost entity is referenced within a Ghost statement
830 else
835 ------------------------
836 -- Check_Ghost_Policy --
837 ------------------------
842 begin
843 -- The Ghost policy in effect a the point of declaration and at the
844 -- point of use must match (SPARK RM 6.9(13)).
862 -- Start of processing for Check_Ghost_Context
864 begin
865 -- Once it has been established that the reference to the Ghost entity
866 -- is within a suitable context, ensure that the policy at the point of
867 -- declaration and at the point of use match.
872 -- Otherwise the Ghost entity appears in a non-Ghost context and affects
873 -- its behavior or value.
875 else
876 SPARK_Msg_N
878 Ghost_Ref);
882 ------------------------------
883 -- Check_Infinite_Recursion --
884 ------------------------------
891 -- Check whether list of actuals is identical to list of formals of
892 -- called function (which is also the enclosing scope).
894 ------------------------
895 -- Same_Argument_List --
896 ------------------------
903 begin
906 else
915 then
926 -- Start of processing for Check_Infinite_Recursion
928 begin
929 -- Special case, if this is a procedure call and is a call to the
930 -- current procedure with the same argument list, then this is for
931 -- sure an infinite recursion and we insert a call to raise SE.
935 and then Same_Argument_List
936 then
937 declare
939 begin
943 then
955 -- If not that special case, search up tree, quitting if we reach a
956 -- construct (e.g. a conditional) that tells us that this is not a
957 -- case for an infinite recursion warning.
960 loop
963 -- If no parent, then we were not inside a subprogram, this can for
964 -- example happen when processing certain pragmas in a spec. Just
965 -- return False in this case.
971 -- Done if we get to subprogram body, this is definitely an infinite
972 -- recursion case if we did not find anything to stop us.
976 -- If appearing in conditional, result is false
979 N_And_Then,
980 N_Case_Expression,
981 N_Case_Statement,
982 N_If_Expression,
983 N_If_Statement)
984 then
989 then
990 -- If the call is the expression of a return statement and the
991 -- actuals are identical to the formals, it's worth a warning.
992 -- However, we skip this if there is an immediately preceding
993 -- raise statement, since the call is never executed.
995 -- Furthermore, this corresponds to a common idiom:
997 -- function F (L : Thing) return Boolean is
998 -- begin
999 -- raise Program_Error;
1000 -- return F (L);
1001 -- end F;
1003 -- for generating a stub function
1006 and then Same_Argument_List
1007 then
1010 -- OK, return statement is in a statement list, look for raise
1012 declare
1015 begin
1016 -- Skip past N_Freeze_Entity nodes generated by expansion
1021 loop
1025 -- If no raise statement, give warning. We look at the
1026 -- original node, because in the case of "raise ... with
1027 -- ...", the node has been transformed into a call.
1030 and then
1038 else
1050 -------------------------------
1051 -- Check_Initialization_Call --
1052 -------------------------------
1058 -- Check whether the creation of an object of the type will involve
1059 -- use of the secondary stack. If T is a record type, this is true
1060 -- if the expression for some component uses the secondary stack, e.g.
1061 -- through a call to a function that returns an unconstrained value.
1062 -- False if T is controlled, because cleanups occur elsewhere.
1064 -------------
1065 -- Uses_SS --
1066 -------------
1073 begin
1074 -- Normally we want to use the underlying type, but if it's not set
1075 -- then continue with T.
1092 then
1093 -- The expression for a dynamic component may be rewritten
1094 -- as a dereference, so retrieve original node.
1098 -- Return True if the expression is a call to a function
1099 -- (including an attribute function such as Image, or a
1100 -- user-defined operator) with a result that requires a
1101 -- transient scope.
1108 then
1121 else
1126 -- Start of processing for Check_Initialization_Call
1128 begin
1129 -- Establish a transient scope if the type needs it
1136 ---------------------------------------
1137 -- Check_No_Direct_Boolean_Operators --
1138 ---------------------------------------
1141 begin
1144 then
1145 -- Restriction only applies to original source code
1152 -- Do style check (but skip if in instance, error is on template)
1161 ------------------------------
1162 -- Check_Parameterless_Call --
1163 ------------------------------
1169 -- If the prefix is of an access_to_subprogram type, the node must be
1170 -- rewritten as a call. Ditto if the prefix is overloaded and all its
1171 -- interpretations are access to subprograms.
1173 ---------------------------
1174 -- Prefix_Is_Access_Subp --
1175 ---------------------------
1181 begin
1182 -- If the context is an attribute reference that can apply to
1183 -- functions, this is never a parameterless call (RM 4.1.4(6)).
1187 Name_Code_Address,
1188 Name_Access)
1189 then
1194 return
1197 else
1202 then
1213 -- Start of processing for Check_Parameterless_Call
1215 begin
1216 -- Defend against junk stuff if errors already detected
1223 then
1230 -- If the context expects a value, and the name is a procedure, this is
1231 -- most likely a missing 'Access. Don't try to resolve the parameterless
1232 -- call, error will be caught when the outer call is analyzed.
1237 and then
1239 N_Function_Call,
1240 N_Procedure_Call_Statement)
1241 then
1245 -- Rewrite as call if overloadable entity that is (or could be, in the
1246 -- overloaded case) a function call. If we know for sure that the entity
1247 -- is an enumeration literal, we do not rewrite it.
1249 -- If the entity is the name of an operator, it cannot be a call because
1250 -- operators cannot have default parameters. In this case, this must be
1251 -- a string whose contents coincide with an operator name. Set the kind
1252 -- of the node appropriately.
1260 -- Rewrite as call if it is an explicit dereference of an expression of
1261 -- a subprogram access type, and the subprogram type is not that of a
1262 -- procedure or entry.
1264 or else
1267 -- Rewrite as call if it is a selected component which is a function,
1268 -- this is the case of a call to a protected function (which may be
1269 -- overloaded with other protected operations).
1271 or else
1274 or else
1276 E_Procedure)
1279 -- If one of the above three conditions is met, rewrite as call. Apply
1280 -- the rewriting only once.
1282 then
1285 then
1287 -- This may be a prefixed call that was not fully analyzed, e.g.
1288 -- an actual in an instance.
1293 then
1301 -- The node is the name of the parameterless call. Preserve its
1302 -- descendants, which may be complex expressions.
1306 -- If overloaded, overload set belongs to new copy
1310 -- Change node to parameterless function call (note that the
1311 -- Parameter_Associations associations field is left set to Empty,
1312 -- its normal default value since there are no parameters)
1330 --------------------------------
1331 -- Is_Atomic_Ref_With_Address --
1332 --------------------------------
1337 begin
1341 else
1342 declare
1345 begin
1353 -----------------------------
1354 -- Is_Definite_Access_Type --
1355 -----------------------------
1359 begin
1365 ----------------------
1366 -- Is_Predefined_Op --
1367 ----------------------
1370 begin
1371 -- Predefined operators are intrinsic subprograms
1377 -- A call to a back-end builtin is never a predefined operator
1388 -----------------------------
1389 -- Make_Call_Into_Operator --
1390 -----------------------------
1392 procedure Make_Call_Into_Operator
1396 is
1411 -- If the operand is not universal, and the operator is given by an
1412 -- expanded name, verify that the operand has an interpretation with a
1413 -- type defined in the given scope of the operator.
1416 -- Find a type of the given class in package Pack that contains the
1417 -- operator.
1419 ---------------------------
1420 -- Operand_Type_In_Scope --
1421 ---------------------------
1428 begin
1432 else
1446 ---------------
1447 -- Type_In_P --
1448 ---------------
1454 -- Verify that node is not part of the type declaration for the
1455 -- candidate type, which would otherwise be invisible.
1457 -------------
1458 -- In_Decl --
1459 -------------
1465 begin
1474 else
1477 loop
1480 else
1489 -- Start of processing for Type_In_P
1491 begin
1492 -- If the context type is declared in the prefix package, this is the
1493 -- desired base type.
1498 else
1502 and then not In_Decl
1503 then
1514 -- Start of processing for Make_Call_Into_Operator
1516 begin
1519 -- Binary operator
1529 -- Unary operator
1531 else
1537 -- If the operator is denoted by an expanded name, and the prefix is
1538 -- not Standard, but the operator is a predefined one whose scope is
1539 -- Standard, then this is an implicit_operator, inserted as an
1540 -- interpretation by the procedure of the same name. This procedure
1541 -- overestimates the presence of implicit operators, because it does
1542 -- not examine the type of the operands. Verify now that the operand
1543 -- type appears in the given scope. If right operand is universal,
1544 -- check the other operand. In the case of concatenation, either
1545 -- argument can be the component type, so check the type of the result.
1546 -- If both arguments are literals, look for a type of the right kind
1547 -- defined in the given scope. This elaborate nonsense is brought to
1548 -- you courtesy of b33302a. The type itself must be frozen, so we must
1549 -- find the type of the proper class in the given scope.
1551 -- A final wrinkle is the multiplication operator for fixed point types,
1552 -- which is defined in Standard only, and not in the scope of the
1553 -- fixed point type itself.
1558 -- If this is a package renaming, get renamed entity, which will be
1559 -- the scope of the operands if operaton is type-correct.
1565 -- If the entity being called is defined in the given package, it is
1566 -- a renaming of a predefined operator, and known to be legal.
1570 then
1573 -- Visibility does not need to be checked in an instance: if the
1574 -- operator was not visible in the generic it has been diagnosed
1575 -- already, else there is an implicit copy of it in the instance.
1583 then
1588 -- Ada 2005 AI-420: Predefined equality on Universal_Access is
1589 -- available.
1594 then
1597 else
1606 and then Is_Binary
1608 then
1614 -- Verify that the scope contains a type that corresponds to
1615 -- the given literal. Optimize the case where Pack is Standard.
1637 else
1646 else
1655 then
1658 -- If the type is defined elsewhere, and the operator is not
1659 -- defined in the given scope (by a renaming declaration, e.g.)
1660 -- then this is an error as well. If an extension of System is
1661 -- present, and the type may be defined there, Pack must be
1662 -- System itself.
1669 then
1672 else
1678 then
1685 Error_Msg_NE
1690 -- Detect a mismatch between the context type and the result type
1691 -- in the named package, which is otherwise not detected if the
1692 -- operands are universal. Check is only needed if source entity is
1693 -- an operator, not a function that renames an operator.
1700 and then not In_Instance
1701 then
1704 then
1705 -- Already checked above
1709 -- Operator may be defined in an extension of System
1713 then
1716 else
1717 -- Could we use Wrong_Type here??? (this would require setting
1718 -- Etype (N) to the actual type found where Typ was expected).
1729 else
1733 -- If this is a call to a function that renames a predefined equality,
1734 -- the renaming declaration provides a type that must be used to
1735 -- resolve the operands. This must be done now because resolution of
1736 -- the equality node will not resolve any remaining ambiguity, and it
1737 -- assumes that the first operand is not overloaded.
1742 then
1750 -- Do rewrite setting Comes_From_Source on the result if the original
1751 -- call came from source. Although it is not strictly the case that the
1752 -- operator as such comes from the source, logically it corresponds
1753 -- exactly to the function call in the source, so it should be marked
1754 -- this way (e.g. to make sure that validity checks work fine).
1756 declare
1758 begin
1763 -- If this is an arithmetic operator and the result type is private,
1764 -- the operands and the result must be wrapped in conversion to
1765 -- expose the underlying numeric type and expand the proper checks,
1766 -- e.g. on division.
1770 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
1771 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
1780 else
1784 -- If in ASIS_Mode, propagate operand types to original actuals of
1785 -- function call, which would otherwise not be fully resolved. If
1786 -- the call has already been constant-folded, nothing to do. We
1787 -- relocate the operand nodes rather than copy them, to preserve
1788 -- original_node pointers, given that the operands themselves may
1789 -- have been rewritten. If the call was itself a rewriting of an
1790 -- operator node, nothing to do.
1792 if ASIS_Mode
1795 then
1801 else
1810 -------------------
1811 -- Operator_Kind --
1812 -------------------
1814 function Operator_Kind
1817 is
1820 begin
1821 -- Use CASE statement or array???
1858 else
1862 -- Unary operators
1864 else
1873 else
1881 ----------------------------
1882 -- Preanalyze_And_Resolve --
1883 ----------------------------
1888 begin
1892 -- Normally, we suppress all checks for this preanalysis. There is no
1893 -- point in processing them now, since they will be applied properly
1894 -- and in the proper location when the default expressions reanalyzed
1895 -- and reexpanded later on. We will also have more information at that
1896 -- point for possible suppression of individual checks.
1898 -- However, in SPARK mode, most expansion is suppressed, and this
1899 -- later reanalysis and reexpansion may not occur. SPARK mode does
1900 -- require the setting of checking flags for proof purposes, so we
1901 -- do the SPARK preanalysis without suppressing checks.
1903 -- This special handling for SPARK mode is required for example in the
1904 -- case of Ada 2012 constructs such as quantified expressions, which are
1905 -- expanded in two separate steps.
1909 else
1913 Expander_Mode_Restore;
1917 -- Version without context type
1922 begin
1929 Expander_Mode_Restore;
1933 ----------------------------------
1934 -- Replace_Actual_Discriminants --
1935 ----------------------------------
1942 -- Comment needed???
1944 -------------------
1945 -- Process_Discr --
1946 -------------------
1951 begin
1957 then
1973 -- Start of processing for Replace_Actual_Discriminants
1975 begin
1989 else
1994 -------------
1995 -- Resolve --
1996 -------------
2012 -- Determine whether a node comes from a predefined library unit or
2013 -- Standard.
2016 -- Try and fix up a literal so that it matches its expected type. New
2017 -- literals are manufactured if necessary to avoid cascaded errors.
2020 -- Additional diagnostics when an ambiguous call has an ambiguous
2021 -- argument (typically a controlling actual).
2024 -- Called when attempt at resolving current expression fails
2026 ------------------------------------
2027 -- Comes_From_Predefined_Lib_Unit --
2028 -------------------------------------
2031 begin
2032 return
2034 or else Is_Predefined_File_Name
2038 --------------------
2039 -- Patch_Up_Value --
2040 --------------------
2043 begin
2060 then
2065 Char_Literal_Value =>
2081 -------------------------------
2082 -- Report_Ambiguous_Argument --
2083 -------------------------------
2090 begin
2094 then
2097 -- Could use comments on what is going on here???
2105 else
2114 -----------------------
2115 -- Resolution_Failed --
2116 -----------------------
2119 begin
2125 -- The caller will return without calling the expander, so we need
2126 -- to set the analyzed flag. Note that it is fine to set Analyzed
2127 -- to True even if we are in the middle of a shallow analysis,
2128 -- (see the spec of sem for more details) since this is an error
2129 -- situation anyway, and there is no point in repeating the
2130 -- analysis later (indeed it won't work to repeat it later, since
2131 -- we haven't got a clear resolution of which entity is being
2132 -- referenced.)
2138 -- Start of processing for Resolve
2140 begin
2145 -- Access attribute on remote subprogram cannot be used for a non-remote
2146 -- access-to-subprogram type.
2150 Name_Unrestricted_Access,
2151 Name_Unchecked_Access)
2157 then
2158 Error_Msg_N
2164 -- If the context is a Remote_Access_To_Subprogram, access attributes
2165 -- must be resolved with the corresponding fat pointer. There is no need
2166 -- to check for the attribute name since the return type of an
2167 -- attribute is never a remote type.
2172 then
2173 declare
2181 begin
2182 -- Check that Typ is a remote access-to-subprogram type
2186 -- Prefix (N) must statically denote a remote subprogram
2187 -- declared in a package specification.
2191 Attr = Attribute_Unrestricted_Access
2192 then
2207 or else
2209 then
2211 Error_Msg_N
2213 N);
2216 -- If we are generating code in distributed mode, perform
2217 -- semantic checks against corresponding remote entities.
2219 if Expander_Active
2221 then
2222 Check_Subtype_Conformant
2224 Old_Id => Designated_Type
2250 then
2255 -- Return if already analyzed
2262 -- Any case of Any_Type as the Etype value means that we had a
2263 -- previous error.
2272 -- The resolution of an Expression_With_Actions is determined by
2273 -- its Expression.
2281 -- If not overloaded, then we know the type, and all that needs doing
2282 -- is to check that this type is compatible with the context.
2288 -- In the overloaded case, we must select the interpretation that
2289 -- is compatible with the context (i.e. the type passed to Resolve)
2291 else
2292 -- Loop through possible interpretations
2302 -- We are only interested in interpretations that are compatible
2303 -- with the expected type, any other interpretations are ignored.
2308 Write_Eol;
2311 else
2312 -- Skip the current interpretation if it is disabled by an
2313 -- abstract operator. This action is performed only when the
2314 -- type against which we are resolving is the same as the
2315 -- type of the interpretation.
2322 then
2330 -- First matching interpretation
2338 -- Matching interpretation that is not the first, maybe an
2339 -- error, but there are some cases where preference rules are
2340 -- used to choose between the two possibilities. These and
2341 -- some more obscure cases are handled in Disambiguate.
2343 else
2344 -- If the current statement is part of a predefined library
2345 -- unit, then all interpretations which come from user level
2346 -- packages should not be considered. Check previous and
2347 -- current one.
2355 -- Previous interpretation must be discarded
2365 -- Otherwise apply further disambiguation steps
2370 -- Disambiguation has succeeded. Skip the remaining
2371 -- interpretations.
2381 else
2382 -- Before we issue an ambiguity complaint, check for
2383 -- the case of a subprogram call where at least one
2384 -- of the arguments is Any_Type, and if so, suppress
2385 -- the message, since it is a cascaded error.
2388 declare
2392 begin
2404 Write_Eol;
2417 then
2422 then
2426 -- Not that special case, so issue message using the
2427 -- flag Ambiguous to control printing of the header
2428 -- message only at the start of an ambiguous set.
2433 then
2434 Error_Msg_N
2437 else
2438 Error_Msg_NE -- CODEFIX
2446 Error_Msg_N
2448 else
2449 Error_Msg_N -- CODEFIX
2455 then
2456 Report_Ambiguous_Argument;
2462 -- By default, the error message refers to the candidate
2463 -- interpretation. But if it is a predefined operator, it
2464 -- is implicitly declared at the declaration of the type
2465 -- of the operand. Recover the sloc of that declaration
2466 -- for the error message.
2472 Standard_Standard
2473 then
2478 then
2486 Standard_Standard
2487 then
2492 then
2496 -- If this is an indirect call, use the subprogram_type
2497 -- in the message, to have a meaningful location. Also
2498 -- indicate if this is an inherited operation, created
2499 -- by a type declaration.
2504 then
2506 Error_Msg_Sloc :=
2508 else
2515 then
2516 -- Special-case the message for universal_fixed
2517 -- operators, which are not declared with the type
2518 -- of the operand, but appear forever in Standard.
2522 then
2523 Error_Msg_N
2526 else
2527 Error_Msg_N
2531 elsif
2533 then
2534 Error_Msg_N
2536 else
2537 Error_Msg_N -- CODEFIX
2544 -- We have a matching interpretation, Expr_Type is the type
2545 -- from this interpretation, and Seen is the entity.
2547 -- For an operator, just set the entity name. The type will be
2548 -- set by the specific operator resolution routine.
2563 -- AI05-0139-2: Expression is overloaded because type has
2564 -- implicit dereference. If type matches context, no implicit
2565 -- dereference is involved.
2576 then
2577 -- If the node is a general indexing, the dereference is
2578 -- is inserted when resolving the rewritten form, else
2579 -- insert it now.
2583 then
2587 -- For an explicit dereference, attribute reference, range,
2588 -- short-circuit form (which is not an operator node), or call
2589 -- with a name that is an explicit dereference, there is
2590 -- nothing to be done at this point.
2593 N_Attribute_Reference,
2594 N_And_Then,
2595 N_Indexed_Component,
2596 N_Or_Else,
2597 N_Range,
2598 N_Selected_Component,
2599 N_Slice)
2601 then
2604 -- For procedure or function calls, set the type of the name,
2605 -- and also the entity pointer for the prefix.
2609 then
2616 then
2621 -- For all other cases, just set the type of the Name
2623 else
2631 -- Move to next interpretation
2639 -- At this stage Found indicates whether or not an acceptable
2640 -- interpretation exists. If not, then we have an error, except that if
2641 -- the context is Any_Type as a result of some other error, then we
2642 -- suppress the error report.
2647 -- If type we are looking for is Void, then this is the procedure
2648 -- call case, and the error is simply that what we gave is not a
2649 -- procedure name (we think of procedure calls as expressions with
2650 -- types internally, but the user doesn't think of them this way).
2654 -- Special case message if function used as a procedure
2659 then
2660 Error_Msg_NE
2664 -- Otherwise give general message (not clear what cases this
2665 -- covers, but no harm in providing for them).
2667 else
2673 -- Otherwise we do have a subexpression with the wrong type
2675 -- Check for the case of an allocator which uses an access type
2676 -- instead of the designated type. This is a common error and we
2677 -- specialize the message, posting an error on the operand of the
2678 -- allocator, complaining that we expected the designated type of
2679 -- the allocator.
2685 then
2689 -- Check for view mismatch on Null in instances, for which the
2690 -- view-swapping mechanism has no identifier.
2696 then
2701 -- Check for an aggregate. Sometimes we can get bogus aggregates
2702 -- from misuse of parentheses, and we are about to complain about
2703 -- the aggregate without even looking inside it.
2705 -- Instead, if we have an aggregate of type Any_Composite, then
2706 -- analyze and resolve the component fields, and then only issue
2707 -- another message if we get no errors doing this (otherwise
2708 -- assume that the errors in the aggregate caused the problem).
2712 then
2713 -- Disable expansion in any case. If there is a type mismatch
2714 -- it may be fatal to try to expand the aggregate. The flag
2715 -- would otherwise be set to false when the error is posted.
2719 declare
2721 -- Check one aggregate, and set Found to True if we have a
2722 -- definite error in any of its elements
2725 -- Check one element of aggregate and set Found to True if
2726 -- we definitely have an error in the element.
2728 ----------------
2729 -- Check_Aggr --
2730 ----------------
2735 begin
2748 -- If this is a default-initialized component, then
2749 -- there is nothing to check. The box will be
2750 -- replaced by the appropriate call during late
2751 -- expansion.
2762 ----------------
2763 -- Check_Elmt --
2764 ----------------
2767 begin
2768 -- If we have a nested aggregate, go inside it (to
2769 -- attempt a naked analyze-resolve of the aggregate can
2770 -- cause undesirable cascaded errors). Do not resolve
2771 -- expression if it needs a type from context, as for
2772 -- integer * fixed expression.
2777 else
2782 then
2792 begin
2797 -- Looks like we have a type error, but check for special case
2798 -- of Address wanted, integer found, with the configuration pragma
2799 -- Allow_Integer_Address active. If we have this case, introduce
2800 -- an unchecked conversion to allow the integer expression to be
2801 -- treated as an Address. The reverse case of integer wanted,
2802 -- Address found, is treated in an analogous manner.
2810 -- That special Allow_Integer_Address check did not appply, so we
2811 -- have a real type error. If an error message was issued already,
2812 -- Found got reset to True, so if it's still False, issue standard
2813 -- Wrong_Type message.
2817 declare
2820 begin
2826 -- Protected operation: retrieve operation name
2830 else
2835 Error_Msg_NE
2841 declare
2845 begin
2852 Error_Msg_NE
2858 else
2862 else
2868 Resolution_Failed;
2871 -- Test if we have more than one interpretation for the context
2874 Resolution_Failed;
2877 -- Only one intepretation
2879 else
2880 -- In Ada 2005, if we have something like "X : T := 2 + 2;", where
2881 -- the "+" on T is abstract, and the operands are of universal type,
2882 -- the above code will have (incorrectly) resolved the "+" to the
2883 -- universal one in Standard. Therefore check for this case and give
2884 -- an error. We can't do this earlier, because it would cause legal
2885 -- cases to get errors (when some other type has an abstract "+").
2891 then
2896 then
2897 Error_Msg_NE
2906 -- Here we have an acceptable interpretation for the context
2908 -- Propagate type information and normalize tree for various
2909 -- predefined operations. If the context only imposes a class of
2910 -- types, rather than a specific type, propagate the actual type
2911 -- downward.
2917 Typ = Any_Discrete
2918 then
2921 -- Any_Fixed is legal in a real context only if a specific fixed-
2922 -- point type is imposed. If Norman Cohen can be confused by this,
2923 -- it deserves a separate message.
2927 then
2934 -- A user-defined operator is transformed into a function call at
2935 -- this point, so that further processing knows that operators are
2936 -- really operators (i.e. are predefined operators). User-defined
2937 -- operators that are intrinsic are just renamings of the predefined
2938 -- ones, and need not be turned into calls either, but if they rename
2939 -- a different operator, we must transform the node accordingly.
2940 -- Instantiations of Unchecked_Conversion are intrinsic but are
2941 -- treated as functions, even if given an operator designator.
2946 then
2952 and then
2954 N_Subprogram_Renaming_Declaration
2955 then
2958 -- If the node is rewritten, it will be fully resolved in
2959 -- Rewrite_Renamed_Operator.
2969 when N_Aggregate => Resolve_Aggregate (N, Ctx_Type);
2971 when N_Allocator => Resolve_Allocator (N, Ctx_Type);
2973 when N_Short_Circuit
2974 => Resolve_Short_Circuit (N, Ctx_Type);
2976 when N_Attribute_Reference
2977 => Resolve_Attribute (N, Ctx_Type);
2979 when N_Case_Expression
2980 => Resolve_Case_Expression (N, Ctx_Type);
2982 when N_Character_Literal
2983 => Resolve_Character_Literal (N, Ctx_Type);
2985 when N_Expanded_Name
2986 => Resolve_Entity_Name (N, Ctx_Type);
2988 when N_Explicit_Dereference
2989 => Resolve_Explicit_Dereference (N, Ctx_Type);
2991 when N_Expression_With_Actions
2992 => Resolve_Expression_With_Actions (N, Ctx_Type);
2994 when N_Extension_Aggregate
2995 => Resolve_Extension_Aggregate (N, Ctx_Type);
2997 when N_Function_Call
2998 => Resolve_Call (N, Ctx_Type);
3000 when N_Identifier
3001 => Resolve_Entity_Name (N, Ctx_Type);
3003 when N_If_Expression
3004 => Resolve_If_Expression (N, Ctx_Type);
3006 when N_Indexed_Component
3007 => Resolve_Indexed_Component (N, Ctx_Type);
3009 when N_Integer_Literal
3010 => Resolve_Integer_Literal (N, Ctx_Type);
3012 when N_Membership_Test
3013 => Resolve_Membership_Op (N, Ctx_Type);
3015 when N_Null => Resolve_Null (N, Ctx_Type);
3017 when N_Op_And | N_Op_Or | N_Op_Xor
3018 => Resolve_Logical_Op (N, Ctx_Type);
3020 when N_Op_Eq | N_Op_Ne
3021 => Resolve_Equality_Op (N, Ctx_Type);
3023 when N_Op_Lt | N_Op_Le | N_Op_Gt | N_Op_Ge
3024 => Resolve_Comparison_Op (N, Ctx_Type);
3026 when N_Op_Not => Resolve_Op_Not (N, Ctx_Type);
3028 when N_Op_Add | N_Op_Subtract | N_Op_Multiply |
3029 N_Op_Divide | N_Op_Mod | N_Op_Rem
3031 => Resolve_Arithmetic_Op (N, Ctx_Type);
3033 when N_Op_Concat => Resolve_Op_Concat (N, Ctx_Type);
3035 when N_Op_Expon => Resolve_Op_Expon (N, Ctx_Type);
3037 when N_Op_Plus | N_Op_Minus | N_Op_Abs
3038 => Resolve_Unary_Op (N, Ctx_Type);
3040 when N_Op_Shift => Resolve_Shift (N, Ctx_Type);
3042 when N_Procedure_Call_Statement
3043 => Resolve_Call (N, Ctx_Type);
3045 when N_Operator_Symbol
3046 => Resolve_Operator_Symbol (N, Ctx_Type);
3048 when N_Qualified_Expression
3049 => Resolve_Qualified_Expression (N, Ctx_Type);
3051 -- Why is the following null, needs a comment ???
3053 when N_Quantified_Expression
3054 => null;
3056 when N_Raise_Expression
3057 => Resolve_Raise_Expression (N, Ctx_Type);
3059 when N_Raise_xxx_Error
3060 => Set_Etype (N, Ctx_Type);
3062 when N_Range => Resolve_Range (N, Ctx_Type);
3064 when N_Real_Literal
3065 => Resolve_Real_Literal (N, Ctx_Type);
3067 when N_Reference => Resolve_Reference (N, Ctx_Type);
3069 when N_Selected_Component
3070 => Resolve_Selected_Component (N, Ctx_Type);
3072 when N_Slice => Resolve_Slice (N, Ctx_Type);
3074 when N_String_Literal
3075 => Resolve_String_Literal (N, Ctx_Type);
3077 when N_Type_Conversion
3078 => Resolve_Type_Conversion (N, Ctx_Type);
3080 when N_Unchecked_Expression =>
3081 Resolve_Unchecked_Expression (N, Ctx_Type);
3083 when N_Unchecked_Type_Conversion =>
3084 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
3085 end case;
3087 -- Ada 2012 (AI05-0149): Apply an (implicit) conversion to an
3088 -- expression of an anonymous access type that occurs in the context
3089 -- of a named general access type, except when the expression is that
3090 -- of a membership test. This ensures proper legality checking in
3091 -- terms of allowed conversions (expressions that would be illegal to
3092 -- convert implicitly are allowed in membership tests).
3094 if Ada_Version >= Ada_2012
3095 and then Ekind (Ctx_Type) = E_General_Access_Type
3096 and then Ekind (Etype (N)) = E_Anonymous_Access_Type
3097 and then Nkind (Parent (N)) not in N_Membership_Test
3098 then
3099 Rewrite (N, Convert_To (Ctx_Type, Relocate_Node (N)));
3100 Analyze_And_Resolve (N, Ctx_Type);
3101 end if;
3103 -- If the subexpression was replaced by a non-subexpression, then
3104 -- all we do is to expand it. The only legitimate case we know of
3105 -- is converting procedure call statement to entry call statements,
3106 -- but there may be others, so we are making this test general.
3108 if Nkind (N) not in N_Subexpr then
3109 Debug_A_Exit ("resolving ", N, " (done)");
3110 Expand (N);
3111 return;
3112 end if;
3114 -- The expression is definitely NOT overloaded at this point, so
3115 -- we reset the Is_Overloaded flag to avoid any confusion when
3116 -- reanalyzing the node.
3118 Set_Is_Overloaded (N, False);
3120 -- Freeze expression type, entity if it is a name, and designated
3121 -- type if it is an allocator (RM 13.14(10,11,13)).
3123 -- Now that the resolution of the type of the node is complete, and
3124 -- we did not detect an error, we can expand this node. We skip the
3125 -- expand call if we are in a default expression, see section
3126 -- "Handling of Default Expressions" in Sem spec.
3128 Debug_A_Exit ("resolving ", N, " (done)");
3130 -- We unconditionally freeze the expression, even if we are in
3131 -- default expression mode (the Freeze_Expression routine tests this
3132 -- flag and only freezes static types if it is set).
3134 -- Ada 2012 (AI05-177): The declaration of an expression function
3135 -- does not cause freezing, but we never reach here in that case.
3136 -- Here we are resolving the corresponding expanded body, so we do
3137 -- need to perform normal freezing.
3139 Freeze_Expression (N);
3141 -- Now we can do the expansion
3143 Expand (N);
3144 end if;
3145 end Resolve;
3147 -------------
3148 -- Resolve --
3149 -------------
3151 -- Version with check(s) suppressed
3153 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
3154 begin
3155 if Suppress = All_Checks then
3156 declare
3157 Sva : constant Suppress_Array := Scope_Suppress.Suppress;
3158 begin
3159 Scope_Suppress.Suppress := (others => True);
3160 Resolve (N, Typ);
3161 Scope_Suppress.Suppress := Sva;
3162 end;
3164 else
3165 declare
3166 Svg : constant Boolean := Scope_Suppress.Suppress (Suppress);
3167 begin
3168 Scope_Suppress.Suppress (Suppress) := True;
3169 Resolve (N, Typ);
3170 Scope_Suppress.Suppress (Suppress) := Svg;
3171 end;
3172 end if;
3173 end Resolve;
3175 -------------
3176 -- Resolve --
3177 -------------
3179 -- Version with implicit type
3181 procedure Resolve (N : Node_Id) is
3182 begin
3183 Resolve (N, Etype (N));
3184 end Resolve;
3186 ---------------------
3187 -- Resolve_Actuals --
3188 ---------------------
3190 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
3191 Loc : constant Source_Ptr := Sloc (N);
3192 A : Node_Id;
3193 A_Id : Entity_Id;
3194 A_Typ : Entity_Id;
3195 F : Entity_Id;
3196 F_Typ : Entity_Id;
3197 Prev : Node_Id := Empty;
3198 Orig_A : Node_Id;
3200 procedure Check_Aliased_Parameter;
3201 -- Check rules on aliased parameters and related accessibility rules
3202 -- in (RM 3.10.2 (10.2-10.4)).
3204 procedure Check_Argument_Order;
3205 -- Performs a check for the case where the actuals are all simple
3206 -- identifiers that correspond to the formal names, but in the wrong
3207 -- order, which is considered suspicious and cause for a warning.
3209 procedure Check_Prefixed_Call;
3210 -- If the original node is an overloaded call in prefix notation,
3212 -- Try_Object_Operation has already verified that there is a valid
3213 -- interpretation, but the form of the actual can only be determined
3214 -- once the primitive operation is identified.
3217 -- If the actual is missing in a call, insert in the actuals list
3218 -- an instance of the default expression. The insertion is always
3219 -- a named association.
3221 procedure Property_Error
3225 -- Emit an error concerning variable Var with entity Var_Id that has
3226 -- enabled property Prop_Nam when it acts as an actual parameter in a
3227 -- call and the corresponding formal parameter is of mode IN.
3230 -- Check whether T1 and T2, or their full views, are derived from a
3231 -- common type. Used to enforce the restrictions on array conversions
3232 -- of AI95-00246.
3235 -- Predicate to determine whether an actual that is a concatenation
3236 -- will be evaluated statically and does not need a transient scope.
3237 -- This must be determined before the actual is resolved and expanded
3238 -- because if needed the transient scope must be introduced earlier.
3240 ------------------------------
3241 -- Check_Aliased_Parameter --
3242 ------------------------------
3247 begin
3255 else
3262 -- In a generic body assume the worst for generic formals:
3263 -- they can have a constrained partial view (AI05-041).
3269 then
3272 else
3277 else
3289 then
3297 then
3298 Error_Msg_N
3304 --------------------------
3305 -- Check_Argument_Order --
3306 --------------------------
3309 begin
3310 -- Nothing to do if no parameters, or original node is neither a
3311 -- function call nor a procedure call statement (happens in the
3312 -- operator-transformed-to-function call case), or the call does
3313 -- not come from source, or this warning is off.
3315 if not Warn_On_Parameter_Order
3319 then
3323 declare
3326 begin
3327 -- Nothing to do if only one parameter
3333 -- Here if at least two arguments
3335 declare
3341 -- Set True if an out of order case is found
3343 begin
3344 -- Collect identifier names of actuals, fail if any actual is
3345 -- not a simple identifier, and record max length of name.
3351 else
3357 -- If we got this far, all actuals are identifiers and the list
3358 -- of their names is stored in the Actuals array.
3363 -- If we ran out of formals, that's odd, probably an error
3364 -- which will be detected elsewhere, but abandon the search.
3370 -- If name matches and is in order OK
3375 else
3376 -- If no match, see if it is elsewhere in list and if so
3377 -- flag potential wrong order if type is compatible.
3381 and then
3383 then
3389 -- No match
3397 -- If Formals left over, also probably an error, skip warning
3403 -- Here we give the warning if something was out of order
3406 Error_Msg_N
3413 -------------------------
3414 -- Check_Prefixed_Call --
3415 -------------------------
3424 begin
3425 -- Check whether the call is a prefixed call, with or without
3426 -- additional actuals.
3429 or else
3435 then
3438 then
3439 -- Introduce dereference on object in prefix
3441 New_A :=
3449 then
3450 -- Introduce an implicit 'Access in prefix
3453 Error_Msg_NE
3469 --------------------
3470 -- Insert_Default --
3471 --------------------
3477 begin
3478 -- Missing argument in call, nothing to insert
3483 else
3484 -- Note that we do a full New_Copy_Tree, so that any associated
3485 -- Itypes are properly copied. This may not be needed any more,
3486 -- but it does no harm as a safety measure. Defaults of a generic
3487 -- formal may be out of bounds of the corresponding actual (see
3488 -- cc1311b) and an additional check may be required.
3490 Actval :=
3491 New_Copy_Tree
3498 then
3504 then
3507 then
3508 -- If default is a real literal, do not introduce a
3509 -- conversion whose effect may depend on the run-time
3510 -- size of universal real.
3514 else
3525 -- Resolve aggregates with their base type, to avoid scope
3526 -- anomalies: the subtype was first built in the subprogram
3527 -- declaration, and the current call may be nested.
3531 else
3535 else
3538 -- See note above concerning aggregates
3542 then
3545 -- Resolve entities with their own type, which may differ from
3546 -- the type of a reference in a generic context (the view
3547 -- swapping mechanism did not anticipate the re-analysis of
3548 -- default values in calls).
3553 else
3558 -- If default is a tag indeterminate function call, propagate tag
3559 -- to obtain proper dispatching.
3563 then
3569 -- If the default expression raises constraint error, then just
3570 -- silently replace it with an N_Raise_Constraint_Error node, since
3571 -- we already gave the warning on the subprogram spec. If node is
3572 -- already a Raise_Constraint_Error leave as is, to prevent loops in
3573 -- the warnings removal machinery.
3577 then
3585 Assoc :=
3590 -- Case of insertion is first named actual
3594 then
3601 else
3605 else
3609 -- Case of insertion is not first named actual
3611 else
3612 Set_Next_Named_Actual
3624 --------------------
3625 -- Property_Error --
3626 --------------------
3628 procedure Property_Error
3632 is
3633 begin
3635 Error_Msg_NE
3641 -------------------
3642 -- Same_Ancestor --
3643 -------------------
3649 begin
3652 then
3658 then
3665 --------------------------
3666 -- Static_Concatenation --
3667 --------------------------
3670 begin
3677 -- Concatenation is static when both operands are static and
3678 -- the concatenation operator is a predefined one.
3681 and then
3683 and then
3688 declare
3690 begin
3693 and then
3697 else
3703 -- Start of processing for Resolve_Actuals
3705 begin
3706 Check_Argument_Order;
3710 Check_Prefixed_Call;
3719 -- If we have an error in any actual or formal, indicated by a type
3720 -- of Any_Type, then abandon resolution attempt, and set result type
3721 -- to Any_Type. Skip this if the actual is a Raise_Expression, whose
3722 -- type is imposed from context.
3726 then
3733 -- Case where actual is present
3735 -- If the actual is an entity, generate a reference to it now. We
3736 -- do this before the actual is resolved, because a formal of some
3737 -- protected subprogram, or a task discriminant, will be rewritten
3738 -- during expansion, and the source entity reference may be lost.
3743 then
3749 then
3756 -- RM 6.4.1(12): For an out parameter that is passed by
3757 -- copy, the formal parameter object is created, and:
3759 -- * For an access type, the formal parameter is initialized
3760 -- from the value of the actual, without checking that the
3761 -- value satisfies any constraint, any predicate, or any
3762 -- exclusion of the null value.
3764 -- * For a scalar type that has the Default_Value aspect
3765 -- specified, the formal parameter is initialized from the
3766 -- value of the actual, without checking that the value
3767 -- satisfies any constraint or any predicate.
3768 -- I do not understand why this case is included??? this is
3769 -- not a case where an OUT parameter is treated as IN OUT.
3771 -- * For a composite type with discriminants or that has
3772 -- implicit initial values for any subcomponents, the
3773 -- behavior is as for an in out parameter passed by copy.
3775 -- Hence for these cases we generate the read reference now
3776 -- (the write reference will be generated later by
3777 -- Note_Possible_Modification).
3780 and then
3782 or else
3784 and then
3786 or else
3789 or else Is_Partially_Initialized_Type
3791 then
3801 then
3802 -- If style checking mode on, check match of formal name
3810 -- If the formal is Out or In_Out, do not resolve and expand the
3811 -- conversion, because it is subsequently expanded into explicit
3812 -- temporaries and assignments. However, the object of the
3813 -- conversion can be resolved. An exception is the case of tagged
3814 -- type conversion with a class-wide actual. In that case we want
3815 -- the tag check to occur and no temporary will be needed (no
3816 -- representation change can occur) and the parameter is passed by
3817 -- reference, so we go ahead and resolve the type conversion.
3818 -- Another exception is the case of reference to component or
3819 -- subcomponent of a bit-packed array, in which case we want to
3820 -- defer expansion to the point the in and out assignments are
3821 -- performed.
3826 then
3829 then
3830 -- In a view conversion, the conversion must be legal in
3831 -- both directions, and thus both component types must be
3832 -- aliased, or neither (4.6 (8)).
3834 -- The extra rule in 4.6 (24.9.2) seems unduly restrictive:
3835 -- the privacy requirement should not apply to generic
3836 -- types, and should be checked in an instance. ARG query
3837 -- is in order ???
3841 then
3842 Error_Msg_N
3846 -- Comment here??? what set of cases???
3848 elsif
3850 then
3851 -- Check view conv between unrelated by ref array types
3855 then
3856 Error_Msg_N
3860 -- In Ada 2005 mode, check view conversion component
3861 -- type cannot be private, tagged, or volatile. Note
3862 -- that we only apply this to source conversions. The
3863 -- generated code can contain conversions which are
3864 -- not subject to this test, and we cannot extract the
3865 -- component type in such cases since it is not present.
3869 then
3870 declare
3872 Component_Type
3874 begin
3879 then
3880 Error_Msg_N
3891 -- Resolve expression if conversion is all OK
3896 then
3900 -- If the actual is a function call that returns a limited
3901 -- unconstrained object that needs finalization, create a
3902 -- transient scope for it, so that it can receive the proper
3903 -- finalization list.
3908 and then Expander_Active
3910 then
3914 -- A small optimization: if one of the actuals is a concatenation
3915 -- create a block around a procedure call to recover stack space.
3916 -- This alleviates stack usage when several procedure calls in
3917 -- the same statement list use concatenation. We do not perform
3918 -- this wrapping for code statements, where the argument is a
3919 -- static string, and we want to preserve warnings involving
3920 -- sequences of such statements.
3924 and then Expander_Active
3925 and then
3929 then
3933 else
3937 and then
3940 then
3941 Error_Msg_N
3954 -- (Ada 2005: AI-251): If the actual is an allocator whose
3955 -- directly designated type is a class-wide interface, we build
3956 -- an anonymous access type to use it as the type of the
3957 -- allocator. Later, when the subprogram call is expanded, if
3958 -- the interface has a secondary dispatch table the expander
3959 -- will add a type conversion to force the correct displacement
3960 -- of the pointer.
3963 declare
3969 begin
3972 then
3975 Set_Directly_Designated_Type
3980 -- Ada 2005, AI-162:If the actual is an allocator, the
3981 -- innermost enclosing statement is the master of the
3982 -- created object. This needs to be done with expansion
3983 -- enabled only, otherwise the transient scope will not
3984 -- be removed in the expansion of the wrapped construct.
3987 and then Expander_Active
3988 then
3998 -- (Ada 2005): The call may be to a primitive operation of a
3999 -- tagged synchronized type, declared outside of the type. In
4000 -- this case the controlling actual must be converted to its
4001 -- corresponding record type, which is the formal type. The
4002 -- actual may be a subtype, either because of a constraint or
4003 -- because it is a generic actual, so use base type to locate
4004 -- concurrent type.
4011 then
4012 -- If the actual is overloaded, look for an interpretation
4013 -- that has a synchronized type.
4018 else
4019 declare
4023 begin
4028 then
4038 declare
4041 begin
4044 else
4048 -- Tagged synchronized type (case 1): the actual is a
4049 -- concurrent type.
4053 then
4055 Unchecked_Convert_To
4059 -- Tagged synchronized type (case 2): the formal is a
4060 -- concurrent type.
4063 and then Present
4068 then
4071 -- Common case
4073 else
4078 -- Not a synchronized operation
4080 else
4088 -- An actual cannot be an untagged formal incomplete type
4093 then
4094 Error_Msg_N
4100 N_Procedure_Call_Statement)
4101 then
4102 -- In formal mode, check that actual parameters matching
4103 -- formals of tagged types are objects (or ancestor type
4104 -- conversions of objects), not general expressions.
4111 declare
4116 begin
4118 Check_SPARK_05_Restriction
4121 -- In formal mode, the only view conversions are those
4122 -- involving ancestor conversion of an extended type.
4124 elsif not
4130 then
4131 if Ekind_In
4133 then
4134 Check_SPARK_05_Restriction
4137 else
4138 Check_SPARK_05_Restriction
4142 else
4147 else
4151 -- In formal mode, the only view conversions are those
4152 -- involving ancestor conversion of an extended type.
4156 then
4157 Check_SPARK_05_Restriction
4163 -- has warnings suppressed, then we reset Never_Set_In_Source for
4164 -- the calling entity. The reason for this is to catch cases like
4165 -- GNAT.Spitbol.Patterns.Vstring_Var where the called subprogram
4166 -- uses trickery to modify an IN parameter.
4173 then
4177 -- Perform error checks for IN and IN OUT parameters
4181 -- Check unset reference. For scalar parameters, it is clearly
4182 -- wrong to pass an uninitialized value as either an IN or
4183 -- IN-OUT parameter. For composites, it is also clearly an
4184 -- error to pass a completely uninitialized value as an IN
4185 -- parameter, but the case of IN OUT is trickier. We prefer
4186 -- not to give a warning here. For example, suppose there is
4187 -- a routine that sets some component of a record to False.
4188 -- It is perfectly reasonable to make this IN-OUT and allow
4189 -- either initialized or uninitialized records to be passed
4190 -- in this case.
4192 -- For partially initialized composite values, we also avoid
4193 -- warnings, since it is quite likely that we are passing a
4194 -- partially initialized value and only the initialized fields
4195 -- will in fact be read in the subprogram.
4200 then
4204 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
4205 -- actual to a nested call, since this is case of reading an
4206 -- out parameter, which is not allowed.
4211 then
4216 -- Case of OUT or IN OUT parameter
4220 -- For an Out parameter, check for useless assignment. Note
4221 -- that we can't set Last_Assignment this early, because we may
4222 -- kill current values in Resolve_Call, and that call would
4223 -- clobber the Last_Assignment field.
4225 -- Note: call Warn_On_Useless_Assignment before doing the check
4226 -- below for Is_OK_Variable_For_Out_Formal so that the setting
4227 -- of Referenced_As_LHS/Referenced_As_Out_Formal properly
4228 -- reflects the last assignment, not this one.
4235 then
4240 -- Validate the form of the actual. Note that the call to
4241 -- Is_OK_Variable_For_Out_Formal generates the required
4242 -- reference in this case.
4244 -- A call to an initialization procedure for an aggregate
4245 -- component may initialize a nested component of a constant
4246 -- designated object. In this context the object is variable.
4250 then
4254 and then
4257 then
4258 Error_Msg_N
4264 -- What's the following about???
4268 else
4269 Kill_All_Checks;
4278 -- Apply appropriate constraint/predicate checks for IN [OUT] case
4282 -- Apply predicate tests except in certain special cases. Note
4283 -- that it might be more consistent to apply these only when
4284 -- expansion is active (in Exp_Ch6.Expand_Actuals), as we do
4285 -- for the outbound predicate tests ???
4291 -- Apply required constraint checks
4293 -- Gigi looks at the check flag and uses the appropriate types.
4294 -- For now since one flag is used there is an optimization
4295 -- which might not be done in the IN OUT case since Gigi does
4296 -- not do any analysis. More thought required about this ???
4298 -- In fact is this comment obsolete??? doesn't the expander now
4299 -- generate all these tests anyway???
4312 then
4315 -- For view conversions of a discriminated object, apply
4316 -- check to object itself, the conversion alreay has the
4317 -- proper type.
4321 then
4328 then
4334 then
4337 else
4341 -- Ada 2005 (AI-231): Note that the controlling parameter case
4342 -- already existed in Ada 95, which is partially checked
4343 -- elsewhere (see Checks), and we don't want the warning
4344 -- message to differ.
4349 then
4351 Apply_Compile_Time_Constraint_Error
4357 Apply_Compile_Time_Constraint_Error
4366 -- Checks for OUT parameters and IN OUT parameters
4370 -- If there is a type conversion, to make sure the return value
4371 -- meets the constraints of the variable before the conversion.
4375 Apply_Scalar_Range_Check
4377 else
4378 Apply_Range_Check
4382 -- If no conversion apply scalar range checks and length checks
4383 -- base on the subtype of the actual (NOT that of the formal).
4385 else
4390 then
4392 else
4397 -- Note: we do not apply the predicate checks for the case of
4398 -- OUT and IN OUT parameters. They are instead applied in the
4399 -- Expand_Actuals routine in Exp_Ch6.
4402 -- An actual associated with an access parameter is implicitly
4403 -- converted to the anonymous access type of the formal and must
4404 -- satisfy the legality checks for access conversions.
4408 Error_Msg_N
4412 -- If the actual is an access selected component of a variable,
4413 -- the call may modify its designated object. It is reasonable
4414 -- to treat this as a potential modification of the enclosing
4415 -- record, to prevent spurious warnings that it should be
4416 -- declared as a constant, because intuitively programmers
4417 -- regard the designated subcomponent as part of the record.
4422 then
4427 -- Check bad case of atomic/volatile argument (RM C.6(12))
4431 then
4434 then
4435 Error_Msg_NE
4441 then
4442 Error_Msg_NE
4448 -- Check that subprograms don't have improper controlling
4449 -- arguments (RM 3.9.2 (9)).
4451 -- A primitive operation may have an access parameter of an
4452 -- incomplete tagged type, but a dispatching call is illegal
4453 -- if the type is still incomplete.
4459 declare
4461 begin
4465 then
4466 Error_Msg_NE
4480 then
4485 Error_Msg_NE
4489 -- Apply the checks described in 3.10.2(27): if the context is a
4490 -- specific access-to-object, the actual cannot be class-wide.
4491 -- Use base type to exclude access_to_subprogram cases.
4498 and then
4503 -- Disable these checks for call to imported C++ subprograms
4505 and then not
4509 then
4510 Error_Msg_N
4515 Error_Msg_NE
4520 Check_Aliased_Parameter;
4524 -- If it is a named association, treat the selector_name as a
4525 -- proper identifier, and mark the corresponding entity.
4529 -- Ignore reference in SPARK mode, as it refers to an entity not
4530 -- in scope at the point of reference, so the reference should
4531 -- be ignored for computing effects of subprograms.
4533 and then not GNATprove_Mode
4534 then
4547 -- The following checks are only relevant when SPARK_Mode is on as
4548 -- they are not standard Ada legality rule. Internally generated
4549 -- temporaries are ignored.
4554 then
4555 -- An effectively volatile object may act as an actual
4556 -- parameter when the corresponding formal is of a non-scalar
4557 -- volatile type.
4561 then
4564 -- An effectively volatile object may act as an actual
4565 -- parameter in a call to an instance of Unchecked_Conversion.
4570 else
4571 Error_Msg_N
4576 -- Detect an external variable with an enabled property that
4577 -- does not match the mode of the corresponding formal in a
4578 -- procedure call. Functions are not considered because they
4579 -- cannot have effectively volatile formal parameters in the
4580 -- first place.
4586 then
4600 then
4602 Error_Msg_NE
4606 Error_Msg_N
4612 -- A formal parameter of a specific tagged type whose related
4613 -- subprogram is subject to pragma Extensions_Visible with value
4614 -- "False" cannot act as an actual in a subprogram with value
4615 -- "True" (SPARK RM 6.1.7(3)).
4619 Extensions_Visible_True
4620 then
4621 Error_Msg_N
4624 Error_Msg_NE
4630 -- Case where actual is not present
4632 else
4633 Insert_Default;
4640 -----------------------
4641 -- Resolve_Allocator --
4642 -----------------------
4654 procedure Check_Allocator_Discrim_Accessibility
4657 -- Check that accessibility level associated with an access discriminant
4658 -- initialized in an allocator by the expression Disc_Exp is not deeper
4659 -- than the level of the allocator type Alloc_Typ. An error message is
4660 -- issued if this condition is violated. Specialized checks are done for
4661 -- the cases of a constraint expression which is an access attribute or
4662 -- an access discriminant.
4665 -- If the allocator is an actual in a call, it is allowed to be class-
4666 -- wide when the context is not because it is a controlling actual.
4668 -------------------------------------------
4669 -- Check_Allocator_Discrim_Accessibility --
4670 -------------------------------------------
4672 procedure Check_Allocator_Discrim_Accessibility
4675 is
4676 begin
4679 then
4680 Error_Msg_N
4683 -- When the expression is an Access attribute the level of the prefix
4684 -- object must not be deeper than that of the allocator's type.
4688 Attribute_Access
4691 then
4692 Error_Msg_N
4694 Disc_Exp);
4696 -- When the expression is an access discriminant the check is against
4697 -- the level of the prefix object.
4703 then
4704 Error_Msg_N
4706 Disc_Exp);
4708 -- All other cases are legal
4710 else
4715 ----------------------------
4716 -- In_Dispatching_Context --
4717 ----------------------------
4722 begin
4728 -- Start of processing for Resolve_Allocator
4730 begin
4731 -- Replace general access with specific type
4741 -- For qualified expression, resolve the expression using the given
4742 -- subtype (nothing to do for type mark, subtype indication)
4747 and then not In_Dispatching_Context
4748 then
4749 Error_Msg_N
4757 -- A qualified expression requires an exact match of the type.
4758 -- Class-wide matching is not allowed.
4763 then
4767 -- Calls to build-in-place functions are not currently supported in
4768 -- allocators for access types associated with a simple storage pool.
4769 -- Supporting such allocators may require passing additional implicit
4770 -- parameters to build-in-place functions (or a significant revision
4771 -- of the current b-i-p implementation to unify the handling for
4772 -- multiple kinds of storage pools). ???
4776 then
4777 declare
4780 begin
4782 and then
4783 Present (Get_Rep_Pragma
4785 then
4786 Error_Msg_N
4793 -- A special accessibility check is needed for allocators that
4794 -- constrain access discriminants. The level of the type of the
4795 -- expression used to constrain an access discriminant cannot be
4796 -- deeper than the type of the allocator (in contrast to access
4797 -- parameters, where the level of the actual can be arbitrary).
4799 -- We can't use Valid_Conversion to perform this check because in
4800 -- general the type of the allocator is unrelated to the type of
4801 -- the access discriminant.
4805 then
4812 then
4815 -- Get the first component expression of the aggregate
4825 else
4829 else
4848 else
4853 else
4862 -- For a subtype mark or subtype indication, freeze the subtype
4864 else
4868 Error_Msg_N
4872 -- A special accessibility check is needed for allocators that
4873 -- constrain access discriminants. The level of the type of the
4874 -- expression used to constrain an access discriminant cannot be
4875 -- deeper than the type of the allocator (in contrast to access
4876 -- parameters, where the level of the actual can be arbitrary).
4877 -- We can't use Valid_Conversion to perform this check because
4878 -- in general the type of the allocator is unrelated to the type
4879 -- of the access discriminant.
4884 then
4894 else
4908 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
4909 -- check that the level of the type of the created object is not deeper
4910 -- than the level of the allocator's access type, since extensions can
4911 -- now occur at deeper levels than their ancestor types. This is a
4912 -- static accessibility level check; a run-time check is also needed in
4913 -- the case of an initialized allocator with a class-wide argument (see
4914 -- Expand_Allocator_Expression).
4918 then
4919 declare
4922 begin
4927 else
4933 then
4936 Error_Msg_N
4945 -- Do not apply Ada 2005 accessibility checks on a class-wide
4946 -- allocator if the type given in the allocator is a formal
4947 -- type. A run-time check will be performed in the instance.
4957 -- Check for allocation from an empty storage pool
4962 -- If the context is an unchecked conversion, as may happen within an
4963 -- inlined subprogram, the allocator is being resolved with its own
4964 -- anonymous type. In that case, if the target type has a specific
4965 -- storage pool, it must be inherited explicitly by the allocator type.
4969 then
4970 Set_Associated_Storage_Pool
4978 -- Check that an allocator with task parts isn't for a nested access
4979 -- type when restriction No_Task_Hierarchy applies.
4983 then
4987 -- An illegal allocator may be rewritten as a raise Program_Error
4988 -- statement.
4992 -- An anonymous access discriminant is the definition of a
4993 -- coextension.
4997 N_Discriminant_Specification
4998 then
4999 declare
5003 begin
5006 -- Ada 2012 AI05-0052: If the designated type of the allocator
5007 -- is limited, then the allocator shall not be used to define
5008 -- the value of an access discriminant unless the discriminated
5009 -- type is immutably limited.
5014 then
5015 Error_Msg_N
5021 -- Avoid marking an allocator as a dynamic coextension if it is
5022 -- within a static construct.
5028 -- Cleanup for potential static coextensions
5030 else
5036 -- Report a simple error: if the designated object is a local task,
5037 -- its body has not been seen yet, and its activation will fail an
5038 -- elaboration check.
5045 then
5051 -- Ada 2012 (AI05-0111-3): Detect an attempt to allocate a task or a
5052 -- type with a task component on a subpool. This action must raise
5053 -- Program_Error at runtime.
5059 then
5071 ---------------------------
5072 -- Resolve_Arithmetic_Op --
5073 ---------------------------
5075 -- Used for resolving all arithmetic operators except exponentiation
5086 -- We do the resolution using the base type, because intermediate values
5087 -- in expressions always are of the base type, not a subtype of it.
5090 -- Returns True if N is in a context that expects "any real type"
5093 -- Return True iff given type is Integer or universal real/integer
5096 -- Choose type of integer literal in fixed-point operation to conform
5097 -- to available fixed-point type. T is the type of the other operand,
5098 -- which is needed to determine the expected type of N.
5101 -- Set operand type to T if universal
5103 -------------------------------
5104 -- Expected_Type_Is_Any_Real --
5105 -------------------------------
5108 begin
5109 -- N is the expression after "delta" in a fixed_point_definition;
5110 -- see RM-3.5.9(6):
5113 N_Decimal_Fixed_Point_Definition,
5115 -- N is one of the bounds in a real_range_specification;
5116 -- see RM-3.5.7(5):
5118 N_Real_Range_Specification,
5120 -- N is the expression of a delta_constraint;
5121 -- see RM-J.3(3):
5123 N_Delta_Constraint);
5126 -----------------------------
5127 -- Is_Integer_Or_Universal --
5128 -----------------------------
5135 begin
5141 else
5147 then
5158 ----------------------------
5159 -- Set_Mixed_Mode_Operand --
5160 ----------------------------
5166 begin
5169 -- A universal integer literal is resolved as standard integer
5170 -- except in the case of a fixed-point result, where we leave it
5171 -- as universal (to be handled by Exp_Fixd later on)
5175 else
5183 then
5184 -- A universal real can appear in a fixed-type context. We resolve
5185 -- the literal with that context, even though this might raise an
5186 -- exception prematurely (the other operand may be zero).
5193 then
5194 -- Integer arg in mixed-mode operation. Resolve with universal
5195 -- type, in case preference rule must be applied.
5201 then
5202 -- Not a mixed-mode operation, resolve with context
5208 -- N may itself be a mixed-mode operation, so use context type
5215 then
5216 -- Must be (fixed * fixed) operation, operand must have one
5217 -- compatible interpretation.
5224 then
5225 -- C * F(X) in a fixed context, where C is a real literal or a
5226 -- fixed-point expression. F must have either a fixed type
5227 -- interpretation or an integer interpretation, but not both.
5234 else
5241 else
5249 -- Reanalyze the literal with the fixed type of the context. If
5250 -- context is Universal_Fixed, we are within a conversion, leave
5251 -- the literal as a universal real because there is no usable
5252 -- fixed type, and the target of the conversion plays no role in
5253 -- the resolution.
5255 declare
5259 begin
5262 else
5268 then
5270 else
5278 else
5283 ----------------------
5284 -- Set_Operand_Type --
5285 ----------------------
5288 begin
5291 then
5296 -- Start of processing for Resolve_Arithmetic_Op
5298 begin
5303 then
5307 -- Special-case for mixed-mode universal expressions or fixed point type
5308 -- operation: each argument is resolved separately. The same treatment
5309 -- is required if one of the operands of a fixed point operation is
5310 -- universal real, since in this case we don't do a conversion to a
5311 -- specific fixed-point type (instead the expander handles the case).
5313 -- Set the type of the node to its universal interpretation because
5314 -- legality checks on an exponentiation operand need the context.
5319 then
5330 or else
5333 then
5338 -- If context is a fixed type and one operand is integer, the other
5339 -- is resolved with the type of the context.
5344 then
5351 then
5355 else
5360 -- Check the rule in RM05-4.5.5(19.1/2) disallowing universal_fixed
5361 -- multiplying operators from being used when the expected type is
5362 -- also universal_fixed. Note that B_Typ will be Universal_Fixed in
5363 -- some cases where the expected type is actually Any_Real;
5364 -- Expected_Type_Is_Any_Real takes care of that case.
5368 then
5372 N_Unchecked_Type_Conversion)
5373 then
5380 else
5383 and then not
5385 N_Unchecked_Type_Conversion)
5386 then
5387 Error_Msg_N
5392 -- The expected type is "any real type" in contexts like
5394 -- type T is delta <universal_fixed-expression> ...
5396 -- in which case we need to set the type to Universal_Real
5397 -- so that static expression evaluation will work properly.
5401 else
5411 then
5416 -- If no previous errors, this is only possible if one operand is
5417 -- overloaded and the context is universal. Resolve as such.
5422 else
5424 and then
5426 then
5430 -- If the context is Universal_Fixed and the operands are also
5431 -- universal fixed, this is an error, unless there is only one
5432 -- applicable fixed_point type (usually Duration).
5440 else
5445 else
5450 -- If one of the arguments was resolved to a non-universal type.
5451 -- label the result of the operation itself with the same type.
5452 -- Do the same for the universal argument, if any.
5464 -- In SPARK, a multiplication or division with operands of fixed point
5465 -- types must be qualified or explicitly converted to identify the
5466 -- result type.
5471 and then
5473 then
5474 Check_SPARK_05_Restriction
5478 -- Set overflow and division checking bit
5485 -- Give warning if explicit division by zero
5489 then
5495 or else
5498 then
5499 -- Specialize the warning message according to the operation.
5500 -- The following warnings are for the case
5505 -- For division, we have two cases, for float division
5506 -- of an unconstrained float type, on a machine where
5507 -- Machine_Overflows is false, we don't get an exception
5508 -- at run-time, but rather an infinity or Nan. The Nan
5509 -- case is pretty obscure, so just warn about infinities.
5513 and then not Machine_Overflows_On_Target
5514 then
5515 Error_Msg_N
5519 -- For all other cases, we get a Constraint_Error
5521 else
5522 Apply_Compile_Time_Constraint_Error
5528 Apply_Compile_Time_Constraint_Error
5533 Apply_Compile_Time_Constraint_Error
5537 -- Division by zero can only happen with division, rem,
5538 -- and mod operations.
5544 -- Otherwise just set the flag to check at run time
5546 else
5551 -- If Restriction No_Implicit_Conditionals is active, then it is
5552 -- violated if either operand can be negative for mod, or for rem
5553 -- if both operands can be negative.
5557 then
5558 declare
5565 -- Set if corresponding operand might be negative
5567 begin
5568 Determine_Range
5572 Determine_Range
5576 -- Check if we will be generating conditionals. There are two
5577 -- cases where that can happen, first for REM, the only case
5578 -- is largest negative integer mod -1, where the division can
5579 -- overflow, but we still have to give the right result. The
5580 -- front end generates a test for this annoying case. Here we
5581 -- just test if both operands can be negative (that's what the
5582 -- expander does, so we match its logic here).
5584 -- The second case is mod where either operand can be negative.
5585 -- In this case, the back end has to generate additional tests.
5588 or else
5590 then
5602 ------------------
5603 -- Resolve_Call --
5604 ------------------
5607 function Same_Or_Aliased_Subprograms
5610 -- Returns True if the subprogram entity S is the same as E or else
5611 -- S is an alias of E.
5613 ---------------------------------
5614 -- Same_Or_Aliased_Subprograms --
5615 ---------------------------------
5617 function Same_Or_Aliased_Subprograms
5620 is
5622 begin
5626 -- Local variables
5640 -- Start of processing for Resolve_Call
5642 begin
5643 -- The context imposes a unique interpretation with type Typ on a
5644 -- procedure or function call. Find the entity of the subprogram that
5645 -- yields the expected type, and propagate the corresponding formal
5646 -- constraints on the actuals. The caller has established that an
5647 -- interpretation exists, and emitted an error if not unique.
5649 -- First deal with the case of a call to an access-to-subprogram,
5650 -- dereference made explicit in Analyze_Call.
5656 else
5657 -- Find the interpretation whose type (a subprogram type) has a
5658 -- return type that is compatible with the context. Analysis of
5659 -- the node has established that one exists.
5678 -- If the prefix is not an entity, then resolve it
5684 -- For an indirect call, we always invalidate checks, since we do not
5685 -- know whether the subprogram is local or global. Yes we could do
5686 -- better here, e.g. by knowing that there are no local subprograms,
5687 -- but it does not seem worth the effort. Similarly, we kill all
5688 -- knowledge of current constant values.
5690 Kill_Current_Values;
5692 -- If this is a procedure call which is really an entry call, do
5693 -- the conversion of the procedure call to an entry call. Protected
5694 -- operations use the same circuitry because the name in the call
5695 -- can be an arbitrary expression with special resolution rules.
5700 then
5704 -- Kill checks and constant values, as above for indirect case
5705 -- Who knows what happens when another task is activated?
5707 Kill_Current_Values;
5710 -- Normal subprogram call with name established in Resolve
5716 -- Otherwise we must have the case of an overloaded call
5718 else
5721 -- Initialize Nam to prevent warning (we know it will be assigned
5722 -- in the loop below, but the compiler does not know that).
5742 then
5743 -- The prefix is a parameterless function call that returns an access
5744 -- to subprogram. If parameters are present in the current call, add
5745 -- add an explicit dereference. We use the base type here because
5746 -- within an instance these may be subtypes.
5748 -- The dereference is added either in Analyze_Call or here. Should
5749 -- be consolidated ???
5758 -- Check that a call to Current_Task does not occur in an entry body
5761 declare
5764 begin
5766 loop
5769 -- Exclude calls that occur within the default of a formal
5770 -- parameter of the entry, since those are evaluated outside
5771 -- of the body.
5778 then
5781 Error_Msg_NE
5795 -- Check that a procedure call does not occur in the context of the
5796 -- entry call statement of a conditional or timed entry call. Note that
5797 -- the case of a call to a subprogram renaming of an entry will also be
5798 -- rejected. The test for N not being an N_Entry_Call_Statement is
5799 -- defensive, covering the possibility that the processing of entry
5800 -- calls might reach this point due to later modifications of the code
5801 -- above.
5806 then
5810 -- Ada 2005 (AI-345): If a procedure_call_statement is used
5811 -- for a procedure_or_entry_call, the procedure_name or
5812 -- procedure_prefix of the procedure_call_statement shall denote
5813 -- an entry renamed by a procedure, or (a view of) a primitive
5814 -- subprogram of a limited interface whose first parameter is
5815 -- a controlling parameter.
5820 then
5821 Error_Msg_N
5826 -- If the SPARK_05 restriction is active, we are not allowed
5827 -- to have a call to a subprogram before we see its completion.
5832 -- Don't flag strange internal calls
5837 -- Only flag calls in extended main source
5842 -- Exclude enumeration literals from this processing
5845 then
5846 Check_SPARK_05_Restriction
5850 -- Check that this is not a call to a protected procedure or entry from
5851 -- within a protected function.
5855 -- Freeze the subprogram name if not in a spec-expression. Note that
5856 -- we freeze procedure calls as well as function calls. Procedure calls
5857 -- are not frozen according to the rules (RM 13.14(14)) because it is
5858 -- impossible to have a procedure call to a non-frozen procedure in
5859 -- pure Ada, but in the code that we generate in the expander, this
5860 -- rule needs extending because we can generate procedure calls that
5861 -- need freezing.
5863 -- In Ada 2012, expression functions may be called within pre/post
5864 -- conditions of subsequent functions or expression functions. Such
5865 -- calls do not freeze when they appear within generated bodies,
5866 -- (including the body of another expression function) which would
5867 -- place the freeze node in the wrong scope. An expression function
5868 -- is frozen in the usual fashion, by the appearance of a real body,
5869 -- or at the end of a declarative part.
5873 and then
5876 then
5880 -- For a predefined operator, the type of the result is the type imposed
5881 -- by context, except for a predefined operation on universal fixed.
5882 -- Otherwise The type of the call is the type returned by the subprogram
5883 -- being called.
5890 -- If the subprogram returns an array type, and the context requires the
5891 -- component type of that array type, the node is really an indexing of
5892 -- the parameterless call. Resolve as such. A pathological case occurs
5893 -- when the type of the component is an access to the array type. In
5894 -- this case the call is truly ambiguous.
5897 and then
5900 or else
5903 and then
5905 then
5906 declare
5911 begin
5914 then
5915 Error_Msg_N
5917 else
5920 -- The called entity may be an explicit dereference, in which
5921 -- case there is no entity to set.
5929 or else
5931 and then
5933 then
5936 -- Indexed call to a parameterless function
5938 Index_Node :=
5940 Prefix =>
5943 else
5944 -- An Ada 2005 prefixed call to a primitive operation
5945 -- whose first parameter is the prefix. This prefix was
5946 -- prepended to the parameter list, which is actually a
5947 -- list of indexes. Remove the prefix in order to build
5948 -- the proper indexed component.
5950 Index_Node :=
5952 Prefix =>
5955 Parameter_Associations =>
5956 New_List
5961 -- Preserve the parenthesis count of the node
5965 -- Since we are correcting a node classification error made
5966 -- by the parser, we call Replace rather than Rewrite.
5980 else
5984 -- In the case where the call is to an overloaded subprogram, Analyze
5985 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
5986 -- such a case Normalize_Actuals needs to be called once more to order
5987 -- the actuals correctly. Otherwise the call will have the ordering
5988 -- given by the last overloaded subprogram whether this is the correct
5989 -- one being called or not.
5996 -- In any case, call is fully resolved now. Reset Overload flag, to
5997 -- prevent subsequent overload resolution if node is analyzed again
6002 -- A Ghost entity must appear in a specific context
6008 -- If we are calling the current subprogram from immediately within its
6009 -- body, then that is the case where we can sometimes detect cases of
6010 -- infinite recursion statically. Do not try this in case restriction
6011 -- No_Recursion is in effect anyway, and do it only for source calls.
6016 -- Check violation of SPARK_05 restriction which does not permit
6017 -- a subprogram body to contain a call to the subprogram directly.
6021 then
6022 Check_SPARK_05_Restriction
6026 -- Issue warning for possible infinite recursion in the absence
6027 -- of the No_Recursion restriction.
6032 then
6033 -- Here we detected and flagged an infinite recursion, so we do
6034 -- not need to test the case below for further warnings. Also we
6035 -- are all done if we now have a raise SE node.
6041 -- If call is to immediately containing subprogram, then check for
6042 -- the case of a possible run-time detectable infinite recursion.
6044 else
6048 -- Although in general case, recursion is not statically
6049 -- checkable, the case of calling an immediately containing
6050 -- subprogram is easy to catch.
6054 -- If the recursive call is to a parameterless subprogram,
6055 -- then even if we can't statically detect infinite
6056 -- recursion, this is pretty suspicious, and we output a
6057 -- warning. Furthermore, we will try later to detect some
6058 -- cases here at run time by expanding checking code (see
6059 -- Detect_Infinite_Recursion in package Exp_Ch6).
6061 -- If the recursive call is within a handler, do not emit a
6062 -- warning, because this is a common idiom: loop until input
6063 -- is correct, catch illegal input in handler and restart.
6069 then
6070 -- For the case of a procedure call. We give the message
6071 -- only if the call is the first statement in a sequence
6072 -- of statements, or if all previous statements are
6073 -- simple assignments. This is simply a heuristic to
6074 -- decrease false positives, without losing too many good
6075 -- warnings. The idea is that these previous statements
6076 -- may affect global variables the procedure depends on.
6077 -- We also exclude raise statements, that may arise from
6078 -- constraint checks and are probably unrelated to the
6079 -- intended control flow.
6083 then
6084 declare
6086 begin
6090 N_Raise_Constraint_Error)
6091 then
6100 -- Do not give warning if we are in a conditional context
6102 declare
6104 begin
6110 then
6115 -- Here warning is to be issued
6131 -- Check obsolescent reference to Ada.Characters.Handling subprogram
6135 -- If subprogram name is a predefined operator, it was given in
6136 -- functional notation. Replace call node with operator node, so
6137 -- that actuals can be resolved appropriately.
6145 then
6151 -- Create a transient scope if the resulting type requires it
6153 -- There are several notable exceptions:
6155 -- a) In init procs, the transient scope overhead is not needed, and is
6156 -- even incorrect when the call is a nested initialization call for a
6157 -- component whose expansion may generate adjust calls. However, if the
6158 -- call is some other procedure call within an initialization procedure
6159 -- (for example a call to Create_Task in the init_proc of the task
6160 -- run-time record) a transient scope must be created around this call.
6162 -- b) Enumeration literal pseudo-calls need no transient scope
6164 -- c) Intrinsic subprograms (Unchecked_Conversion and source info
6165 -- functions) do not use the secondary stack even though the return
6166 -- type may be unconstrained.
6168 -- d) Calls to a build-in-place function, since such functions may
6169 -- allocate their result directly in a target object, and cases where
6170 -- the result does get allocated in the secondary stack are checked for
6171 -- within the specialized Exp_Ch6 procedures for expanding those
6172 -- build-in-place calls.
6174 -- e) If the subprogram is marked Inline_Always, then even if it returns
6175 -- an unconstrained type the call does not require use of the secondary
6176 -- stack. However, inlining will only take place if the body to inline
6177 -- is already present. It may not be available if e.g. the subprogram is
6178 -- declared in a child instance.
6180 -- If this is an initialization call for a type whose construction
6181 -- uses the secondary stack, and it is not a nested call to initialize
6182 -- a component, we do need to create a transient scope for it. We
6183 -- check for this by traversing the type in Check_Initialization_Call.
6189 then
6195 then
6198 elsif Expander_Active
6201 and then
6203 or else
6205 then
6208 -- If the call appears within the bounds of a loop, it will
6209 -- be rewritten and reanalyzed, nothing left to do here.
6216 and then not Within_Init_Proc
6217 then
6221 -- A protected function cannot be called within the definition of the
6222 -- enclosing protected type, unless it is part of a pre/postcondition
6223 -- on another protected operation.
6228 and then not In_Spec_Expression
6229 then
6230 Error_Msg_NE
6234 -- Propagate interpretation to actuals, and add default expressions
6235 -- where needed.
6240 -- Overloaded literals are rewritten as function calls, for purpose of
6241 -- resolution. After resolution, we can replace the call with the
6242 -- literal itself.
6248 -- Avoid validation, since it is a static function call
6254 -- If the subprogram is not global, then kill all saved values and
6255 -- checks. This is a bit conservative, since in many cases we could do
6256 -- better, but it is not worth the effort. Similarly, we kill constant
6257 -- values. However we do not need to do this for internal entities
6258 -- (unless they are inherited user-defined subprograms), since they
6259 -- are not in the business of molesting local values.
6261 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
6262 -- kill all checks and values for calls to global subprograms. This
6263 -- takes care of the case where an access to a local subprogram is
6264 -- taken, and could be passed directly or indirectly and then called
6265 -- from almost any context.
6267 -- Note: we do not do this step till after resolving the actuals. That
6268 -- way we still take advantage of the current value information while
6269 -- scanning the actuals.
6271 -- We suppress killing values if we are processing the nodes associated
6272 -- with N_Freeze_Entity nodes. Otherwise the declaration of a tagged
6273 -- type kills all the values as part of analyzing the code that
6274 -- initializes the dispatch tables.
6278 or else Suppress_Value_Tracking_On_Call
6283 then
6284 Kill_Current_Values;
6287 -- If we are warning about unread OUT parameters, this is the place to
6288 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
6289 -- after the above call to Kill_Current_Values (since that call clears
6290 -- the Last_Assignment field of all local variables).
6295 then
6296 declare
6300 begin
6310 then
6320 -- If the subprogram is a primitive operation, check whether or not
6321 -- it is a correct dispatching call.
6325 then
6330 and then not In_Instance
6331 then
6335 -- If this is a dispatching call, generate the appropriate reference,
6336 -- for better source navigation in GPS.
6340 then
6343 -- Normal case, not a dispatching call: generate a call reference
6345 else
6353 -- Check for violation of restriction No_Specific_Termination_Handlers
6354 -- and warn on a potentially blocking call to Abort_Task.
6358 or else
6360 then
6367 -- A call to Ada.Real_Time.Timing_Events.Set_Handler to set a relative
6368 -- timing event violates restriction No_Relative_Delay (AI-0211). We
6369 -- need to check the second argument to determine whether it is an
6370 -- absolute or relative timing event.
6375 then
6379 -- Issue an error for a call to an eliminated subprogram. This routine
6380 -- will not perform the check if the call appears within a default
6381 -- expression.
6385 -- In formal mode, the primitive operations of a tagged type or type
6386 -- extension do not include functions that return the tagged type.
6392 then
6396 -- Implement rule in 12.5.1 (23.3/2): In an instance, if the actual is
6397 -- class-wide and the call dispatches on result in a context that does
6398 -- not provide a tag, the call raises Program_Error.
6401 and then In_Instance
6406 then
6407 -- Verify that none of the formals are controlling
6409 declare
6413 begin
6435 -- Check for calling a function with OUT or IN OUT parameter when the
6436 -- calling context (us right now) is not Ada 2012, so does not allow
6437 -- OUT or IN OUT parameters in function calls.
6442 then
6447 -- Check the dimensions of the actuals in the call. For function calls,
6448 -- propagate the dimensions from the returned type to N.
6452 -- All done, evaluate call and deal with elaboration issues
6457 -- In GNATprove mode, expansion is disabled, but we want to inline some
6458 -- subprograms to facilitate formal verification. Indirect calls through
6459 -- a subprogram type or within a generic cannot be inlined. Inlining is
6460 -- performed only for calls subject to SPARK_Mode on.
6462 if GNATprove_Mode
6465 and then not Inside_A_Generic
6466 then
6473 -- Nothing to do if the subprogram is not eligible for inlining in
6474 -- GNATprove mode.
6478 then
6481 -- Calls cannot be inlined inside assertions, as GNATprove treats
6482 -- assertions as logic expressions.
6489 -- Calls cannot be inlined inside default expressions
6496 -- Inlining should not be performed during pre-analysis
6500 -- With the one-pass inlining technique, a call cannot be
6501 -- inlined if the corresponding body has not been seen yet.
6504 Error_Msg_NE
6509 -- Nothing to do if there is no body to inline, indicating that
6510 -- the subprogram is not suitable for inlining in GNATprove
6511 -- mode.
6516 -- Calls cannot be inlined inside potentially unevaluated
6517 -- expressions, as this would create complex actions inside
6518 -- expressions, that are not handled by GNATprove.
6522 Error_Msg_N
6526 -- Otherwise, inline the call
6528 else
6538 -----------------------------
6539 -- Resolve_Case_Expression --
6540 -----------------------------
6545 begin
6556 -------------------------------
6557 -- Resolve_Character_Literal --
6558 -------------------------------
6564 begin
6565 -- Verify that the character does belong to the type of the context
6570 -- Wide_Wide_Character literals must always be defined, since the set
6571 -- of wide wide character literals is complete, i.e. if a character
6572 -- literal is accepted by the parser, then it is OK for wide wide
6573 -- character (out of range character literals are rejected).
6578 -- Always accept character literal for type Any_Character, which
6579 -- occurs in error situations and in comparisons of literals, both
6580 -- of which should accept all literals.
6585 -- For Standard.Character or a type derived from it, check that the
6586 -- literal is in range.
6593 -- For Standard.Wide_Character or a type derived from it, check that the
6594 -- literal is in range.
6601 -- For Standard.Wide_Wide_Character or a type derived from it, we
6602 -- know the literal is in range, since the parser checked.
6607 -- If the entity is already set, this has already been resolved in a
6608 -- generic context, or comes from expansion. Nothing else to do.
6613 -- Otherwise we have a user defined character type, and we can use the
6614 -- standard visibility mechanisms to locate the referenced entity.
6616 else
6629 -- If we fall through, then the literal does not match any of the
6630 -- entries of the enumeration type. This isn't just a constraint error
6631 -- situation, it is an illegality (see RM 4.2).
6633 Error_Msg_NE
6637 ---------------------------
6638 -- Resolve_Comparison_Op --
6639 ---------------------------
6641 -- Context requires a boolean type, and plays no role in resolution.
6642 -- Processing identical to that for equality operators. The result type is
6643 -- the base type, which matters when pathological subtypes of booleans with
6644 -- limited ranges are used.
6651 begin
6652 -- If this is an intrinsic operation which is not predefined, use the
6653 -- types of its declared arguments to resolve the possibly overloaded
6654 -- operands. Otherwise the operands are unambiguous and specify the
6655 -- expected type.
6660 else
6671 -- Skip remaining processing if already set to Any_Type
6677 -- Deal with other error cases
6681 T = Any_Character
6682 then
6685 else
6693 -- Resolve the operands if types OK
6702 -- In SPARK, ordering operators <, <=, >, >= are not defined for Boolean
6703 -- types or array types except String.
6706 Check_SPARK_05_Restriction
6711 then
6712 Check_SPARK_05_Restriction
6716 -- Check comparison on unordered enumeration
6720 Error_Msg_NE
6725 -- Evaluate the relation (note we do this after the above check since
6726 -- this Eval call may change N to True/False.
6732 -----------------------------------------
6733 -- Resolve_Discrete_Subtype_Indication --
6734 -----------------------------------------
6736 procedure Resolve_Discrete_Subtype_Indication
6739 is
6743 begin
6751 else
6761 Error_Msg_NE
6764 -- Rewrite the constraint as a range of Typ
6765 -- to allow compilation to proceed further.
6777 else
6781 -- Additionally, we must check that the bounds are compatible
6782 -- with the given subtype, which might be different from the
6783 -- type of the context.
6787 -- ??? If the above check statically detects a Constraint_Error
6788 -- it replaces the offending bound(s) of the range R with a
6789 -- Constraint_Error node. When the itype which uses these bounds
6790 -- is frozen the resulting call to Duplicate_Subexpr generates
6791 -- a new temporary for the bounds.
6793 -- Unfortunately there are other itypes that are also made depend
6794 -- on these bounds, so when Duplicate_Subexpr is called they get
6795 -- a forward reference to the newly created temporaries and Gigi
6796 -- aborts on such forward references. This is probably sign of a
6797 -- more fundamental problem somewhere else in either the order of
6798 -- itype freezing or the way certain itypes are constructed.
6800 -- To get around this problem we call Remove_Side_Effects right
6801 -- away if either bounds of R are a Constraint_Error.
6803 declare
6807 begin
6823 -------------------------
6824 -- Resolve_Entity_Name --
6825 -------------------------
6827 -- Used to resolve identifiers and expanded names
6831 -- Denote whether an arbitrary node Nod appears in a check node
6833 function Is_OK_Volatile_Context
6836 -- Determine whether node Context denotes a "non-interfering context"
6837 -- (as defined in SPARK RM 7.1.3(13)) where volatile reference Obj_Ref
6838 -- can safely reside.
6840 ----------------------
6841 -- Appears_In_Check --
6842 ----------------------
6847 begin
6848 -- Climb the parent chain looking for a check node
6855 -- Prevent the search from going too far
6867 ----------------------------
6868 -- Is_OK_Volatile_Context --
6869 ----------------------------
6871 function Is_OK_Volatile_Context
6874 is
6875 begin
6876 -- The volatile object appears on either side of an assignment
6881 -- The volatile object is part of the initialization expression of
6882 -- another object. Ensure that the climb of the parent chain came
6883 -- from the expression side and not from the name side.
6888 then
6891 -- The volatile object appears as an actual parameter in a call to an
6892 -- instance of Unchecked_Conversion whose result is renamed.
6897 then
6900 -- The volatile object appears as the prefix of a name occurring
6901 -- in a non-interfering context.
6904 N_Indexed_Component,
6905 N_Selected_Component,
6906 N_Slice)
6908 and then Is_OK_Volatile_Context
6911 then
6914 -- The volatile object appears as the expression of a type conversion
6915 -- occurring in a non-interfering context.
6918 N_Unchecked_Type_Conversion)
6920 and then Is_OK_Volatile_Context
6923 then
6926 -- Allow references to volatile objects in various checks. This is
6927 -- not a direct SPARK 2014 requirement.
6932 else
6937 -- Local variables
6942 -- Start of processing for Resolve_Entity_Name
6944 begin
6945 -- If garbage from errors, set to Any_Type and return
6952 -- Replace named numbers by corresponding literals. Note that this is
6953 -- the one case where Resolve_Entity_Name must reset the Etype, since
6954 -- it is currently marked as universal.
6964 -- For enumeration literals, we need to make sure that a proper style
6965 -- check is done, since such literals are overloaded, and thus we did
6966 -- not do a style check during the first phase of analysis.
6972 -- Case of subtype name appearing as an operand in expression
6976 -- Allow use of subtype if it is a concurrent type where we are
6977 -- currently inside the body. This will eventually be expanded into a
6978 -- call to Self (for tasks) or _object (for protected objects). Any
6979 -- other use of a subtype is invalid.
6983 then
6986 -- Any other use is an error
6988 else
6989 Error_Msg_N
6993 -- Check discriminant use if entity is discriminant in current scope,
6994 -- i.e. discriminant of record or concurrent type currently being
6995 -- analyzed. Uses in corresponding body are unrestricted.
7000 then
7003 -- A parameterless generic function cannot appear in a context that
7004 -- requires resolution.
7015 then
7018 -- In all other cases, just do the possible static evaluation
7020 else
7021 -- A deferred constant that appears in an expression must have a
7022 -- completion, unless it has been removed by in-place expansion of
7023 -- an aggregate.
7029 and then not In_Spec_Expression
7031 then
7035 then
7037 else
7038 Error_Msg_N (
7048 -- When the entity appears in a parameter association, retrieve the
7049 -- related subprogram call.
7055 -- The following checks are only relevant when SPARK_Mode is on as they
7056 -- are not standard Ada legality rules.
7060 -- An effectively volatile object subject to enabled properties
7061 -- Async_Writers or Effective_Reads must appear in a specific
7062 -- context.
7066 and then
7069 then
7070 -- The effectively volatile objects appears in a "non-interfering
7071 -- context" as defined in SPARK RM 7.1.3(13).
7076 -- Assume that references to effectively volatile objects that
7077 -- appear as actual parameters in a procedure call are always
7078 -- legal. A full legality check is done when the actuals are
7079 -- resolved.
7084 -- Otherwise the context causes a side effect with respect to the
7085 -- effectively volatile object.
7087 else
7088 SPARK_Msg_N
7093 -- A Ghost entity must appear in a specific context
7101 -------------------
7102 -- Resolve_Entry --
7103 -------------------
7115 -- If the bounds of the entry family being called depend on task
7116 -- discriminants, build a new index subtype where a discriminant is
7117 -- replaced with the value of the discriminant of the target task.
7118 -- The target task is the prefix of the entry name in the call.
7120 -----------------------
7121 -- Actual_Index_Type --
7122 -----------------------
7132 -- If the bound is given by a discriminant, replace with a reference
7133 -- to the discriminant of the same name in the target task. If the
7134 -- entry name is the target of a requeue statement and the entry is
7135 -- in the current protected object, the bound to be used is the
7136 -- discriminal of the object (see Apply_Range_Checks for details of
7137 -- the transformation).
7139 -----------------------------
7140 -- Actual_Discriminant_Ref --
7141 -----------------------------
7147 begin
7152 then
7158 then
7159 -- Note: here Bound denotes a discriminant of the corresponding
7160 -- record type tskV, whose discriminal is a formal of the
7161 -- init-proc tskVIP. What we want is the body discriminal,
7162 -- which is associated to the discriminant of the original
7163 -- concurrent type tsk.
7165 return New_Occurrence_Of
7168 else
7169 Ref :=
7179 -- Start of processing for Actual_Index_Type
7181 begin
7184 then
7187 else
7201 -- Start of processing of Resolve_Entry
7203 begin
7204 -- Find name of entry being called, and resolve prefix of name with its
7205 -- own type. The prefix can be overloaded, and the name and signature of
7206 -- the entry must be taken into account.
7210 -- Case of dealing with entry family within the current tasks
7214 else
7220 -- Entry call to an entry (or entry family) in the current task. This
7221 -- is legal even though the task will deadlock. Rewrite as call to
7222 -- current task.
7224 -- This can also be a call to an entry in an enclosing task. If this
7225 -- is a single task, we have to retrieve its name, because the scope
7226 -- of the entry is the task type, not the object. If the enclosing
7227 -- task is a task type, the identity of the task is given by its own
7228 -- self variable.
7230 -- Finally this can be a requeue on an entry of the same task or
7231 -- protected object.
7238 then
7239 -- S is an enclosing task or protected object. The concurrent
7240 -- declaration has been converted into a type declaration, and
7241 -- the object itself has an object declaration that follows
7242 -- the type in the same declarative part.
7254 -- Call to current task. Will be transformed into call to Self
7261 New_N :=
7264 Selector_Name =>
7271 then
7272 -- Use the entry name (which must be unique at this point) to find
7273 -- the prefix that returns the corresponding task/protected type.
7275 declare
7281 begin
7303 -- Up to this point the expression could have been the actual in a
7304 -- simple entry call, and be given by a named association.
7308 else
7314 ------------------------
7315 -- Resolve_Entry_Call --
7316 ------------------------
7328 begin
7329 -- We kill all checks here, because it does not seem worth the effort to
7330 -- do anything better, an entry call is a big operation.
7332 Kill_All_Checks;
7334 -- Processing of the name is similar for entry calls and protected
7335 -- operation calls. Once the entity is determined, we can complete
7336 -- the resolution of the actuals.
7338 -- The selector may be overloaded, in the case of a protected object
7339 -- with overloaded functions. The type of the context is used for
7340 -- resolution.
7345 then
7346 declare
7350 begin
7369 -- Simple entry call
7377 -- Call to member of entry family
7384 -- We cannot in general check the maximum depth of protected entry calls
7385 -- at compile time. But we can tell that any protected entry call at all
7386 -- violates a specified nesting depth of zero.
7392 -- Use context type to disambiguate a protected function that can be
7393 -- called without actuals and that returns an array type, and where the
7394 -- argument list may be an indexing of the returned value.
7399 and then
7405 and then
7406 Covers
7409 then
7410 declare
7413 begin
7414 Index_Node :=
7416 Prefix =>
7420 -- Since we are correcting a node classification error made by the
7421 -- parser, we call Replace rather than Rewrite.
7434 then
7435 -- Rewrite as call to the precondition wrapper, adding the task
7436 -- object to the list of actuals. If the call is to a member of an
7437 -- entry family, include the index as well.
7439 declare
7443 begin
7452 New_Call :=
7454 Name =>
7459 -- Preanalyze and resolve new call. Current procedure is called
7460 -- from Resolve_Call, after which expansion will take place.
7467 -- The operation name may have been overloaded. Order the actuals
7468 -- according to the formals of the resolved entity, and set the return
7469 -- type to that of the operation.
7480 -- Create a call reference to the entry
7488 -- Verify that a procedure call cannot masquerade as an entry
7489 -- call where an entry call is expected.
7494 then
7499 then
7504 then
7509 -- After resolution, entry calls and protected procedure calls are
7510 -- changed into entry calls, for expansion. The structure of the node
7511 -- does not change, so it can safely be done in place. Protected
7512 -- function calls must keep their structure because they are
7513 -- subexpressions.
7517 -- A protected operation that is not a function may modify the
7518 -- corresponding object, and cannot apply to a constant. If this
7519 -- is an internal call, the prefix is the type itself.
7525 then
7526 Error_Msg_N
7528 Entry_Name);
7542 -- Protected functions can return on the secondary stack, in which
7543 -- case we must trigger the transient scope mechanism.
7545 elsif Expander_Active
7547 then
7552 -------------------------
7553 -- Resolve_Equality_Op --
7554 -------------------------
7556 -- Both arguments must have the same type, and the boolean context does
7557 -- not participate in the resolution. The first pass verifies that the
7558 -- interpretation is not ambiguous, and the type of the left argument is
7559 -- correctly set, or is Any_Type in case of ambiguity. If both arguments
7560 -- are strings or aggregates, allocators, or Null, they are ambiguous even
7561 -- though they carry a single (universal) type. Diagnose this case here.
7569 -- The resolution rule for if expressions requires that each such must
7570 -- have a unique type. This means that if several dependent expressions
7571 -- are of a non-null anonymous access type, and the context does not
7572 -- impose an expected type (as can be the case in an equality operation)
7573 -- the expression must be rejected.
7576 -- Attempt to explain the nature of a redundant comparison with True. If
7577 -- the expression N is too complex, this routine issues a general error
7578 -- message.
7581 -- In the case of allocators and access attributes, the context must
7582 -- provide an indication of the specific access type to be used. If
7583 -- one operand is of such a "generic" access type, check whether there
7584 -- is a specific visible access type that has the same designated type.
7585 -- This is semantically dubious, and of no interest to any real code,
7586 -- but c48008a makes it all worthwhile.
7588 -------------------------
7589 -- Check_If_Expression --
7590 -------------------------
7596 begin
7603 then
7609 ------------------------
7610 -- Explain_Redundancy --
7611 ------------------------
7618 begin
7621 -- Strip the operand down to an entity
7623 loop
7626 else
7631 -- The construct denotes an entity
7636 -- Do not generate an error message when the comparison is done
7637 -- against the enumeration literal Standard.True.
7641 -- Build a customized error message
7668 -- The construct is too complex to disect, issue a general message
7670 else
7675 -----------------------------
7676 -- Find_Unique_Access_Type --
7677 -----------------------------
7684 begin
7686 E_Access_Attribute_Type)
7687 then
7691 E_Access_Attribute_Type)
7692 then
7694 else
7706 then
7719 -- Start of processing for Resolve_Equality_Op
7721 begin
7732 T = Any_Character
7733 then
7736 else
7745 then
7754 -- If expressions must have a single type, and if the context does
7755 -- not impose one the dependent expressions cannot be anonymous
7756 -- access types.
7758 -- Why no similar processing for case expressions???
7762 E_Anonymous_Access_Subprogram_Type)
7764 E_Anonymous_Access_Subprogram_Type)
7765 then
7773 -- In SPARK, equality operators = and /= for array types other than
7774 -- String are only defined when, for each index position, the
7775 -- operands have equal static bounds.
7779 -- Protect call to Matching_Static_Array_Bounds to avoid costly
7780 -- operation if not needed.
7788 then
7789 Check_SPARK_05_Restriction
7794 -- If the unique type is a class-wide type then it will be expanded
7795 -- into a dispatching call to the predefined primitive. Therefore we
7796 -- check here for potential violation of such restriction.
7802 if Warn_On_Redundant_Constructs
7807 then
7808 Error_Msg_N -- CODEFIX
7818 -- If this is an inequality, it may be the implicit inequality
7819 -- created for a user-defined operation, in which case the corres-
7820 -- ponding equality operation is not intrinsic, and the operation
7821 -- cannot be constant-folded. Else fold.
7826 or else Is_Intrinsic_Subprogram
7828 then
7834 then
7838 -- Ada 2005: If one operand is an anonymous access type, convert the
7839 -- other operand to it, to ensure that the underlying types match in
7840 -- the back-end. Same for access_to_subprogram, and the conversion
7841 -- verifies that the types are subtype conformant.
7843 -- We apply the same conversion in the case one of the operands is a
7844 -- private subtype of the type of the other.
7846 -- Why the Expander_Active test here ???
7848 if Expander_Active
7849 and then
7851 E_Anonymous_Access_Subprogram_Type)
7853 then
7873 ----------------------------------
7874 -- Resolve_Explicit_Dereference --
7875 ----------------------------------
7883 -- The candidate prefix type, if overloaded
7888 begin
7892 -- A useful optimization: check whether the dereference denotes an
7893 -- element of a container, and if so rewrite it as a call to the
7894 -- corresponding Element function.
7896 -- Disabled for now, on advice of ARG. A more restricted form of the
7897 -- predicate might be acceptable ???
7899 -- if Is_Container_Element (N) then
7900 -- return;
7901 -- end if;
7905 -- Use the context type to select the prefix that has the correct
7906 -- designated type. Keep the first match, which will be the inner-
7907 -- most.
7914 then
7919 -- Remove access types that do not match, but preserve access
7920 -- to subprogram interpretations, in case a further dereference
7921 -- is needed (see below).
7934 else
7935 -- If no interpretation covers the designated type of the prefix,
7936 -- this is the pathological case where not all implementations of
7937 -- the prefix allow the interpretation of the node as a call. Now
7938 -- that the expected type is known, Remove other interpretations
7939 -- from prefix, rewrite it as a call, and resolve again, so that
7940 -- the proper call node is generated.
7951 New_N :=
7953 Name =>
7964 -- If not overloaded, resolve P with its own type
7966 else
7974 -- If the designated type is a packed unconstrained array type, and the
7975 -- explicit dereference is not in the context of an attribute reference,
7976 -- then we must compute and set the actual subtype, since it is needed
7977 -- by Gigi. The reason we exclude the attribute case is that this is
7978 -- handled fine by Gigi, and in fact we use such attributes to build the
7979 -- actual subtype. We also exclude generated code (which builds actual
7980 -- subtypes directly if they are needed).
7987 then
7991 -- Note: No Eval processing is required for an explicit dereference,
7992 -- because such a name can never be static.
7996 -------------------------------------
7997 -- Resolve_Expression_With_Actions --
7998 -------------------------------------
8001 begin
8004 -- If N has no actions, and its expression has been constant folded,
8005 -- then rewrite N as just its expression. Note, we can't do this in
8006 -- the general case of Is_Empty_List (Actions (N)) as this would cause
8007 -- Expression (N) to be expanded again.
8011 then
8016 ----------------------------------
8017 -- Resolve_Generalized_Indexing --
8018 ----------------------------------
8026 begin
8027 -- In ASIS mode, propagate the information about the indices back to
8028 -- to the original indexing node. The generalized indexing is either
8029 -- a function call, or a dereference of one. The actuals include the
8030 -- prefix of the original node, which is the container expression.
8039 loop
8050 else
8056 ---------------------------
8057 -- Resolve_If_Expression --
8058 ---------------------------
8067 begin
8072 -- When the "then" expression is of a scalar subtype different from the
8073 -- result subtype, then insert a conversion to ensure the generation of
8074 -- a constraint check. The same is done for the else part below, again
8075 -- comparing subtypes rather than base types.
8079 then
8084 -- If ELSE expression present, just resolve using the determined type
8092 then
8097 -- If no ELSE expression is present, root type must be Standard.Boolean
8098 -- and we provide a Standard.True result converted to the appropriate
8099 -- Boolean type (in case it is a derived boolean type).
8102 Else_Expr :=
8107 else
8116 -------------------------------
8117 -- Resolve_Indexed_Component --
8118 -------------------------------
8126 begin
8134 -- Use the context type to select the prefix that yields the correct
8135 -- component type.
8137 declare
8144 begin
8151 and then
8152 Covers
8155 then
8164 else
8170 else
8181 else
8188 -- If prefix is access type, dereference to get real array type.
8189 -- Note: we do not apply an access check because the expander always
8190 -- introduces an explicit dereference, and the check will happen there.
8196 -- If name was overloaded, set component type correctly now
8197 -- If a misplaced call to an entry family (which has no index types)
8198 -- return. Error will be diagnosed from calling context.
8202 else
8209 -- The prefix may have resolved to a string literal, in which case its
8210 -- etype has a special representation. This is only possible currently
8211 -- if the prefix is a static concatenation, written in functional
8212 -- notation.
8217 else
8224 else
8235 -- Do not generate the warning on suspicious index if we are analyzing
8236 -- package Ada.Tags; otherwise we will report the warning with the
8237 -- Prims_Ptr field of the dispatch table.
8240 or else not
8242 Ada_Tags)
8243 then
8248 -- If the array type is atomic, and the component is not atomic, then
8249 -- this is worth a warning, since we have a situation where the access
8250 -- to the component may cause extra read/writes of the atomic array
8251 -- object, or partial word accesses, which could be unexpected.
8257 and then Has_Atomic_Components
8260 then
8268 -----------------------------
8269 -- Resolve_Integer_Literal --
8270 -----------------------------
8273 begin
8278 --------------------------------
8279 -- Resolve_Intrinsic_Operator --
8280 --------------------------------
8289 -- If the operand is a literal, it cannot be the expression in a
8290 -- conversion. Use a qualified expression instead.
8295 begin
8297 Res :=
8303 else
8310 -- Start of processing for Resolve_Intrinsic_Operator
8312 begin
8313 -- We must preserve the original entity in a generic setting, so that
8314 -- the legality of the operation can be verified in an instance.
8329 -- If the result or operand types are private, rewrite with unchecked
8330 -- conversions on the operands and the result, to expose the proper
8331 -- underlying numeric type.
8336 then
8338 -- Unchecked_Convert_To (Btyp, Left_Opnd (N));
8339 -- What on earth is this commented out fragment of code???
8343 else
8364 then
8365 -- Add explicit conversion where needed, and save interpretations in
8366 -- case operands are overloaded.
8373 else
8379 else
8389 else
8394 --------------------------------------
8395 -- Resolve_Intrinsic_Unary_Operator --
8396 --------------------------------------
8398 procedure Resolve_Intrinsic_Unary_Operator
8401 is
8406 begin
8425 else
8430 ------------------------
8431 -- Resolve_Logical_Op --
8432 ------------------------
8437 begin
8440 -- Predefined operations on scalar types yield the base type. On the
8441 -- other hand, logical operations on arrays yield the type of the
8442 -- arguments (and the context).
8446 else
8450 -- The following test is required because the operands of the operation
8451 -- may be literals, in which case the resulting type appears to be
8452 -- compatible with a signed integer type, when in fact it is compatible
8453 -- only with modular types. If the context itself is universal, the
8454 -- operation is illegal.
8462 Error_Msg_N
8470 then
8474 -- Replace AND by AND THEN, or OR by OR ELSE, if Short_Circuit_And_Or
8475 -- is active and the result type is standard Boolean (do not mess with
8476 -- ops that return a nonstandard Boolean type, because something strange
8477 -- is going on).
8479 -- Note: you might expect this replacement to be done during expansion,
8480 -- but that doesn't work, because when the pragma Short_Circuit_And_Or
8481 -- is used, no part of the right operand of an "and" or "or" operator
8482 -- should be executed if the left operand would short-circuit the
8483 -- evaluation of the corresponding "and then" or "or else". If we left
8484 -- the replacement to expansion time, then run-time checks associated
8485 -- with such operands would be evaluated unconditionally, due to being
8486 -- before the condition prior to the rewriting as short-circuit forms
8487 -- during expansion.
8489 if Short_Circuit_And_Or
8492 then
8500 -- Case of OR changed to OR ELSE
8502 else
8510 -- Return now, since analysis of the rewritten ops will take care of
8511 -- other reference bookkeeping and expression folding.
8526 -- In SPARK, logical operations AND, OR and XOR for arrays are defined
8527 -- only when both operands have same static lower and higher bounds. Of
8528 -- course the types have to match, so only check if operands are
8529 -- compatible and the node itself has no errors.
8533 then
8534 declare
8538 begin
8539 -- Protect call to Matching_Static_Array_Bounds to avoid costly
8540 -- operation if not needed.
8547 then
8548 Check_SPARK_05_Restriction
8557 ---------------------------
8558 -- Resolve_Membership_Op --
8559 ---------------------------
8561 -- The context can only be a boolean type, and does not determine the
8562 -- arguments. Arguments should be unambiguous, but the preference rule for
8563 -- universal types applies.
8573 -- Analysis has determined a unique type for the left operand. Use it to
8574 -- resolve the disjuncts.
8576 ----------------------------
8577 -- Resolve_Set_Membership --
8578 ----------------------------
8584 begin
8590 -- Alternative is an expression, a range
8591 -- or a subtype mark.
8595 then
8602 -- Check for duplicates for discrete case
8605 declare
8614 begin
8615 -- Loop checking duplicates. This is quadratic, but giant sets
8616 -- are unlikely in this context so it's a reasonable choice.
8623 N_Character_Literal)
8625 then
8643 -- Start of processing for Resolve_Membership_Op
8645 begin
8651 Resolve_Set_Membership;
8655 and then
8657 or else
8660 then
8663 -- Ada 2005 (AI-251): Support the following case:
8665 -- type I is interface;
8666 -- type T is tagged ...
8668 -- function Test (O : I'Class) is
8669 -- begin
8670 -- return O in T'Class.
8671 -- end Test;
8673 -- In this case we have nothing else to do. The membership test will be
8674 -- done at run time.
8681 then
8683 else
8687 -- If mixed-mode operations are present and operands are all literal,
8688 -- the only interpretation involves Duration, which is probably not
8689 -- the intention of the programmer.
8704 then
8710 else
8715 -- Here after resolving membership operation
8723 ------------------
8724 -- Resolve_Null --
8725 ------------------
8730 begin
8731 -- Handle restriction against anonymous null access values This
8732 -- restriction can be turned off using -gnatdj.
8734 -- Ada 2005 (AI-231): Remove restriction
8737 and then not Debug_Flag_J
8740 then
8741 -- In the common case of a call which uses an explicitly null value
8742 -- for an access parameter, give specialized error message.
8745 Error_Msg_N
8748 -- Standard message for all other cases (are there any?)
8750 else
8751 Error_Msg_N
8756 -- Ada 2005 (AI-231): Generate the null-excluding check in case of
8757 -- assignment to a null-excluding object
8762 then
8764 Insert_Action
8769 else
8776 -- In a distributed context, null for a remote access to subprogram may
8777 -- need to be replaced with a special record aggregate. In this case,
8778 -- return after having done the transformation.
8783 then
8787 -- The null literal takes its type from the context
8792 -----------------------
8793 -- Resolve_Op_Concat --
8794 -----------------------
8798 -- We wish to avoid deep recursion, because concatenations are often
8799 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
8800 -- operands nonrecursively until we find something that is not a simple
8801 -- concatenation (A in this case). We resolve that, and then walk back
8802 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
8803 -- to do the rest of the work at each level. The Parent pointers allow
8804 -- us to avoid recursion, and thus avoid running out of memory. See also
8805 -- Sem_Ch4.Analyze_Concatenation, where a similar approach is used.
8810 begin
8811 -- The following code is equivalent to:
8813 -- Resolve_Op_Concat_First (NN, Typ);
8814 -- Resolve_Op_Concat_Arg (N, ...);
8815 -- Resolve_Op_Concat_Rest (N, Typ);
8817 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
8818 -- operand is a concatenation.
8820 -- Walk down left operands
8822 loop
8831 -- Now (given the above example) NN is A&B and Op1 is A
8833 -- First resolve Op1 ...
8837 -- ... then walk NN back up until we reach N (where we started), calling
8838 -- Resolve_Op_Concat_Rest along the way.
8840 loop
8847 Check_SPARK_05_Restriction
8852 ---------------------------
8853 -- Resolve_Op_Concat_Arg --
8854 ---------------------------
8856 procedure Resolve_Op_Concat_Arg
8861 is
8865 begin
8867 if Is_Comp
8871 then
8873 else
8877 -- If both Array & Array and Array & Component are visible, there is a
8878 -- potential ambiguity that must be reported.
8883 then
8887 -- If the operation is user-defined and not overloaded use its
8888 -- profile. The operation may be a renaming, in which case it has
8889 -- been rewritten, and we want the original profile.
8894 then
8896 Etype
8900 -- Otherwise an aggregate may match both the array type and the
8901 -- component type.
8903 else
8908 else
8912 then
8913 declare
8918 begin
8923 -- Special-case the error message when the overloading is
8924 -- caused by a function that yields an array and can be
8925 -- called without parameters.
8930 Error_Msg_NE
8932 Error_Msg_NE
8936 else
8944 or else
8946 then
8947 Error_Msg_N -- CODEFIX
8965 else
8970 else
8974 -- Concatenation is restricted in SPARK: each operand must be either a
8975 -- string literal, the name of a string constant, a static character or
8976 -- string expression, or another concatenation. Arg cannot be a
8977 -- concatenation here as callers of Resolve_Op_Concat_Arg call it
8978 -- separately on each final operand, past concatenation operations.
8982 Check_SPARK_05_Restriction
8990 then
8991 Check_SPARK_05_Restriction
8995 -- Do not issue error on an operand that is neither a character nor a
8996 -- string, as the error is issued in Resolve_Op_Concat.
8998 else
9005 -----------------------------
9006 -- Resolve_Op_Concat_First --
9007 -----------------------------
9014 begin
9015 -- The parser folds an enormous sequence of concatenations of string
9016 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
9017 -- in the right operand. If the expression resolves to a predefined "&"
9018 -- operator, all is well. Otherwise, the parser's folding is wrong, so
9019 -- we give an error. See P_Simple_Expression in Par.Ch4.
9024 then
9039 ----------------------------
9040 -- Resolve_Op_Concat_Rest --
9041 ----------------------------
9047 begin
9056 -- If this is not a static concatenation, but the result is a string
9057 -- type (and not an array of strings) ensure that static string operands
9058 -- have their subtypes properly constructed.
9062 then
9068 ----------------------
9069 -- Resolve_Op_Expon --
9070 ----------------------
9075 begin
9076 -- Catch attempts to do fixed-point exponentiation with universal
9077 -- operands, which is a case where the illegality is not caught during
9078 -- normal operator analysis. This is not done in preanalysis mode
9079 -- since the tree is not fully decorated during preanalysis.
9090 then
9100 then
9107 then
9111 -- We do the resolution using the base type, because intermediate values
9112 -- in expressions are always of the base type, not a subtype of it.
9117 -- For integer types, right argument must be in Natural range
9132 -- Evaluate the exponentiation operator for dimensioned type
9135 else
9139 -- Set overflow checking bit. Much cleverer code needed here eventually
9140 -- and perhaps the Resolve routines should be separated for the various
9141 -- arithmetic operations, since they will need different processing. ???
9150 --------------------
9151 -- Resolve_Op_Not --
9152 --------------------
9158 -- This function determines if the parent node is a boolean operator or
9159 -- operation (comparison op, membership test, or short circuit form) and
9160 -- the not in question is the left operand of this operation. Note that
9161 -- if the not is in parens, then false is returned.
9163 -----------------------
9164 -- Parent_Is_Boolean --
9165 -----------------------
9168 begin
9172 else
9174 when N_Op_And |
9175 N_Op_Eq |
9176 N_Op_Ge |
9177 N_Op_Gt |
9178 N_Op_Le |
9179 N_Op_Lt |
9180 N_Op_Ne |
9181 N_Op_Or |
9182 N_Op_Xor |
9183 N_In |
9184 N_Not_In |
9185 N_And_Then |
9186 N_Or_Else =>
9196 -- Start of processing for Resolve_Op_Not
9198 begin
9199 -- Predefined operations on scalar types yield the base type. On the
9200 -- other hand, logical operations on arrays yield the type of the
9201 -- arguments (and the context).
9205 else
9209 -- Straightforward case of incorrect arguments
9216 -- Special case of probable missing parens
9220 Error_Msg_N
9223 else
9224 Error_Msg_N
9231 -- OK resolution of NOT
9233 else
9234 -- Warn if non-boolean types involved. This is a case like not a < b
9235 -- where a and b are modular, where we will get (not a) < b and most
9236 -- likely not (a < b) was intended.
9238 if Warn_On_Questionable_Missing_Parens
9240 and then Parent_Is_Boolean
9241 then
9245 -- Warn on double negation if checking redundant constructs
9247 if Warn_On_Redundant_Constructs
9252 then
9256 -- Complete resolution and evaluation of NOT
9266 -----------------------------
9267 -- Resolve_Operator_Symbol --
9268 -----------------------------
9270 -- Nothing to be done, all resolved already
9276 begin
9280 ----------------------------------
9281 -- Resolve_Qualified_Expression --
9282 ----------------------------------
9290 begin
9293 -- Protect call to Matching_Static_Array_Bounds to avoid costly
9294 -- operation if not needed.
9301 then
9302 Check_SPARK_05_Restriction
9306 -- A qualified expression requires an exact match of the type, class-
9307 -- wide matching is not allowed. However, if the qualifying type is
9308 -- specific and the expression has a class-wide type, it may still be
9309 -- okay, since it can be the result of the expansion of a call to a
9310 -- dispatching function, so we also have to check class-wideness of the
9311 -- type of the expression's original node.
9314 or else
9318 then
9322 -- If the target type is unconstrained, then we reset the type of the
9323 -- result from the type of the expression. For other cases, the actual
9324 -- subtype of the expression is the target type.
9328 then
9335 -- If we still have a qualified expression after the static evaluation,
9336 -- then apply a scalar range check if needed. The reason that we do this
9337 -- after the Eval call is that otherwise, the application of the range
9338 -- check may convert an illegal static expression and result in warning
9339 -- rather than giving an error (e.g Integer'(Integer'Last + 1)).
9346 ------------------------------
9347 -- Resolve_Raise_Expression --
9348 ------------------------------
9351 begin
9355 else
9360 -------------------
9361 -- Resolve_Range --
9362 -------------------
9369 -- Returns True if N is of the form X'First .. X'Last where X is the
9370 -- same entity for both attributes.
9372 --------------------
9373 -- First_Last_Ref --
9374 --------------------
9380 begin
9385 then
9386 declare
9389 begin
9393 then
9402 -- Start of processing for Resolve_Range
9404 begin
9409 -- Check for inappropriate range on unordered enumeration type
9413 -- Exclude X'First .. X'Last if X is the same entity for both
9415 and then not First_Last_Ref
9416 then
9418 Error_Msg_NE
9425 -- We have to check the bounds for being within the base range as
9426 -- required for a non-static context. Normally this is automatic and
9427 -- done as part of evaluating expressions, but the N_Range node is an
9428 -- exception, since in GNAT we consider this node to be a subexpression,
9429 -- even though in Ada it is not. The circuit in Sem_Eval could check for
9430 -- this, but that would put the test on the main evaluation path for
9431 -- expressions.
9436 -- Check for an ambiguous range over character literals. This will
9437 -- happen with a membership test involving only literals.
9445 -- If bounds are static, constant-fold them, so size computations are
9446 -- identical between front-end and back-end. Do not perform this
9447 -- transformation while analyzing generic units, as type information
9448 -- would be lost when reanalyzing the constant node in the instance.
9461 --------------------------
9462 -- Resolve_Real_Literal --
9463 --------------------------
9468 begin
9469 -- Special processing for fixed-point literals to make sure that the
9470 -- value is an exact multiple of small where this is required. We skip
9471 -- this for the universal real case, and also for generic types.
9477 then
9478 declare
9485 begin
9486 -- Case of literal is not an exact multiple of the Small
9490 -- For a source program literal for a decimal fixed-point type,
9491 -- this is statically illegal (RM 4.9(36)).
9496 then
9500 -- Generate a warning if literal from source
9503 and then Warn_On_Bad_Fixed_Value
9504 then
9505 Error_Msg_N
9507 N);
9510 -- Replace literal by a value that is the exact representation
9511 -- of a value of the type, i.e. a multiple of the small value,
9512 -- by truncation, since Machine_Rounds is false for all GNAT
9513 -- fixed-point types (RM 4.9(38)).
9523 -- In all cases, set the corresponding integer field
9529 -- Now replace the actual type by the expected type as usual
9535 -----------------------
9536 -- Resolve_Reference --
9537 -----------------------
9542 begin
9543 -- Replace general access with specific type
9551 -- If we are taking the reference of a volatile entity, then treat it as
9552 -- a potential modification of this entity. This is too conservative,
9553 -- but necessary because remove side effects can cause transformations
9554 -- of normal assignments into reference sequences that otherwise fail to
9555 -- notice the modification.
9562 --------------------------------
9563 -- Resolve_Selected_Component --
9564 --------------------------------
9579 -- Check whether this is the initialization of a component within an
9580 -- init proc (by assignment or call to another init proc). If true,
9581 -- there is no need for a discriminant check.
9583 --------------------
9584 -- Init_Component --
9585 --------------------
9588 begin
9589 return Inside_Init_Proc
9595 -- Start of processing for Resolve_Selected_Component
9597 begin
9600 -- Use the context type to select the prefix that has a selector
9601 -- of the correct name and type.
9609 else
9613 -- Locate selected component. For a private prefix the selector
9614 -- can denote a discriminant.
9618 -- The visible components of a class-wide type are those of
9619 -- the root type.
9629 then
9636 else
9640 Error_Msg_N
9645 else
9648 -- There may be an implicit dereference. Retrieve
9649 -- designated record type.
9653 else
9659 -- Resolution chooses the new interpretation.
9660 -- Find the component with the right name.
9665 loop
9682 -- There must be a legal interpretation at this point
9689 else
9690 -- Resolve prefix with its type
9695 -- Generate cross-reference. We needed to wait until full overloading
9696 -- resolution was complete to do this, since otherwise we can't tell if
9697 -- we are an lvalue or not.
9701 else
9705 -- If prefix is an access type, the node will be transformed into an
9706 -- explicit dereference during expansion. The type of the node is the
9707 -- designated type of that of the prefix.
9712 else
9716 -- Set flag for expander if discriminant check required
9723 and then not Init_Component
9724 then
9732 -- If the prefix is a record conversion, this may be a renamed
9733 -- discriminant whose bounds differ from those of the original
9734 -- one, so we must ensure that a range check is performed.
9739 then
9743 -- Note: No Eval processing is required, because the prefix is of a
9744 -- record type, or protected type, and neither can possibly be static.
9746 -- If the record type is atomic, and the component is non-atomic, then
9747 -- this is worth a warning, since we have a situation where the access
9748 -- to the component may cause extra read/writes of the atomic array
9749 -- object, or partial word accesses, both of which may be unexpected.
9755 then
9756 Error_Msg_N
9759 Error_Msg_N
9767 -------------------
9768 -- Resolve_Shift --
9769 -------------------
9776 begin
9777 -- We do the resolution using the base type, because intermediate values
9778 -- in expressions always are of the base type, not a subtype of it.
9791 ---------------------------
9792 -- Resolve_Short_Circuit --
9793 ---------------------------
9800 begin
9801 -- Ensure all actions associated with the left operand (e.g.
9802 -- finalization of transient controlled objects) are fully evaluated
9803 -- locally within an expression with actions. This is particularly
9804 -- helpful for coverage analysis. However this should not happen in
9805 -- generics.
9808 declare
9810 begin
9818 -- Set Comes_From_Source on L to preserve warnings for unset
9819 -- reference.
9828 -- Check for issuing warning for always False assert/check, this happens
9829 -- when assertions are turned off, in which case the pragma Assert/Check
9830 -- was transformed into:
9832 -- if False and then <condition> then ...
9834 -- and we detect this pattern
9836 if Warn_On_Assertion_Failure
9843 then
9844 declare
9847 begin
9848 -- Special handling of Asssert pragma
9852 then
9853 declare
9855 Original_Node
9856 (Expression
9859 begin
9860 -- Don't warn if original condition is explicit False,
9861 -- since obviously the failure is expected in this case.
9865 then
9868 -- Issue warning. We do not want the deletion of the
9869 -- IF/AND-THEN to take this message with it. We achieve this
9870 -- by making sure that the expanded code points to the Sloc
9871 -- of the expression, not the original pragma.
9873 else
9874 -- Note: Use Error_Msg_F here rather than Error_Msg_N.
9875 -- The source location of the expression is not usually
9876 -- the best choice here. For example, it gets located on
9877 -- the last AND keyword in a chain of boolean expressiond
9878 -- AND'ed together. It is best to put the message on the
9879 -- first character of the assertion, which is the effect
9880 -- of the First_Node call here.
9882 Error_Msg_F
9884 Expression
9889 -- Similar processing for Check pragma
9893 then
9894 -- Don't want to warn if original condition is explicit False
9896 declare
9898 Original_Node
9899 (Expression
9901 begin
9904 then
9907 -- Post warning
9909 else
9910 -- Again use Error_Msg_F rather than Error_Msg_N, see
9911 -- comment above for an explanation of why we do this.
9913 Error_Msg_F
9915 Expression
9923 -- Continue with processing of short circuit
9932 -------------------
9933 -- Resolve_Slice --
9934 -------------------
9943 begin
9946 -- Use the context type to select the prefix that yields the correct
9947 -- array type.
9949 declare
9956 begin
9964 then
9972 else
9977 else
9988 else
9998 -- If the prefix is an access to an unconstrained array, we must use
9999 -- the actual subtype of the object to perform the index checks. The
10000 -- object denoted by the prefix is implicit in the node, so we build
10001 -- an explicit representation for it in order to compute the actual
10002 -- subtype.
10007 declare
10011 begin
10022 then
10025 -- If the name is a selected component that depends on discriminants,
10026 -- build an actual subtype for it. This can happen only when the name
10027 -- itself is overloaded; otherwise the actual subtype is created when
10028 -- the selected component is analyzed.
10031 and then Full_Analysis
10033 then
10034 declare
10037 begin
10042 -- Maybe this should just be "else", instead of checking for the
10043 -- specific case of slice??? This is needed for the case where the
10044 -- prefix is an Image attribute, which gets expanded to a slice, and so
10045 -- has a constrained subtype which we want to use for the slice range
10046 -- check applied below (the range check won't get done if the
10047 -- unconstrained subtype of the 'Image is used).
10053 -- Obtain the type of the array index
10057 else
10061 -- If name was overloaded, set slice type correctly now
10065 -- Handle the generation of a range check that compares the array index
10066 -- against the discrete_range. The check is not applied to internally
10067 -- built nodes associated with the expansion of dispatch tables. Check
10068 -- that Ada.Tags has already been loaded to avoid extra dependencies on
10069 -- the unit.
10071 if Tagged_Type_Expansion
10077 then
10080 -- The discrete_range is specified by a subtype indication. Create a
10081 -- shallow copy and inherit the type, parent and source location from
10082 -- the discrete_range. This ensures that the range check is inserted
10083 -- relative to the slice and that the runtime exception points to the
10084 -- proper construct.
10093 -- The discrete_range is a regular range. Resolve the bounds and remove
10094 -- their side effects.
10096 else
10113 -- Check bad use of type with predicates
10115 declare
10118 begin
10121 then
10123 else
10128 Bad_Predicated_Subtype_Use
10133 -- Otherwise here is where we check suspicious indexes
10144 ----------------------------
10145 -- Resolve_String_Literal --
10146 ----------------------------
10157 begin
10158 -- For a string appearing in a concatenation, defer creation of the
10159 -- string_literal_subtype until the end of the resolution of the
10160 -- concatenation, because the literal may be constant-folded away. This
10161 -- is a useful optimization for long concatenation expressions.
10163 -- If the string is an aggregate built for a single character (which
10164 -- happens in a non-static context) or a is null string to which special
10165 -- checks may apply, we build the subtype. Wide strings must also get a
10166 -- string subtype if they come from a one character aggregate. Strings
10167 -- generated by attributes might be static, but it is often hard to
10168 -- determine whether the enclosing context is static, so we generate
10169 -- subtypes for them as well, thus losing some rarer optimizations ???
10170 -- Same for strings that come from a static conversion.
10172 Need_Check :=
10181 -- If the resolving type is itself a string literal subtype, we can just
10182 -- reuse it, since there is no point in creating another.
10188 and then not Need_Check
10190 N_Attribute_Reference,
10191 N_Qualified_Expression,
10192 N_Type_Conversion)
10193 then
10196 -- Do not generate a string literal subtype for the default expression
10197 -- of a formal parameter in GNATprove mode. This is because the string
10198 -- subtype is associated with the freezing actions of the subprogram,
10199 -- however freezing is disabled in GNATprove mode and as a result the
10200 -- subtype is unavailable.
10202 elsif GNATprove_Mode
10204 then
10207 -- Otherwise we must create a string literal subtype. Note that the
10208 -- whole idea of string literal subtypes is simply to avoid the need
10209 -- for building a full fledged array subtype for each literal.
10211 else
10217 or else Need_Check
10218 then
10225 then
10231 -- The validity of a null string has been checked in the call to
10232 -- Eval_String_Literal.
10237 -- Always accept string literal with component type Any_Character, which
10238 -- occurs in error situations and in comparisons of literals, both of
10239 -- which should accept all literals.
10244 -- If the type is bit-packed, then we always transform the string
10245 -- literal into a full fledged aggregate.
10250 -- Deal with cases of Wide_Wide_String, Wide_String, and String
10252 else
10253 -- For Standard.Wide_Wide_String, or any other type whose component
10254 -- type is Standard.Wide_Wide_Character, we know that all the
10255 -- characters in the string must be acceptable, since the parser
10256 -- accepted the characters as valid character literals.
10261 -- For the case of Standard.String, or any other type whose component
10262 -- type is Standard.Character, we must make sure that there are no
10263 -- wide characters in the string, i.e. that it is entirely composed
10264 -- of characters in range of type Character.
10266 -- If the string literal is the result of a static concatenation, the
10267 -- test has already been performed on the components, and need not be
10268 -- repeated.
10272 then
10276 -- If we are out of range, post error. This is one of the
10277 -- very few places that we place the flag in the middle of
10278 -- a token, right under the offending wide character. Not
10279 -- quite clear if this is right wrt wide character encoding
10280 -- sequences, but it's only an error message.
10282 Error_Msg
10289 -- For the case of Standard.Wide_String, or any other type whose
10290 -- component type is Standard.Wide_Character, we must make sure that
10291 -- there are no wide characters in the string, i.e. that it is
10292 -- entirely composed of characters in range of type Wide_Character.
10294 -- If the string literal is the result of a static concatenation,
10295 -- the test has already been performed on the components, and need
10296 -- not be repeated.
10300 then
10304 -- If we are out of range, post error. This is one of the
10305 -- very few places that we place the flag in the middle of
10306 -- a token, right under the offending wide character.
10308 -- This is not quite right, because characters in general
10309 -- will take more than one character position ???
10311 Error_Msg
10318 -- If the root type is not a standard character, then we will convert
10319 -- the string into an aggregate and will let the aggregate code do
10320 -- the checking. Standard Wide_Wide_Character is also OK here.
10322 else
10326 -- See if the component type of the array corresponding to the string
10327 -- has compile time known bounds. If yes we can directly check
10328 -- whether the evaluation of the string will raise constraint error.
10329 -- Otherwise we need to transform the string literal into the
10330 -- corresponding character aggregate and let the aggregate code do
10331 -- the checking.
10335 -- Check for the case of full range, where we are definitely OK
10341 -- Here the range is not the complete base type range, so check
10343 declare
10351 begin
10354 then
10360 then
10361 Apply_Compile_Time_Constraint_Error
10363 CE_Range_Check_Failed,
10374 -- If we got here we meed to transform the string literal into the
10375 -- equivalent qualified positional array aggregate. This is rather
10376 -- heavy artillery for this situation, but it is hard work to avoid.
10378 declare
10383 begin
10384 -- Build the character literals, we give them source locations that
10385 -- correspond to the string positions, which is a bit tricky given
10386 -- the possible presence of wide character escape sequences.
10400 -- Should we have a call to Skip_Wide here ???
10402 -- ??? else
10403 -- Skip_Wide (P);
10411 Expression =>
10418 -----------------------------
10419 -- Resolve_Type_Conversion --
10420 -----------------------------
10432 -- Set to False to suppress cases where we want to suppress the test
10433 -- for redundancy to avoid possible false positives on this warning.
10435 begin
10436 if not Conv_OK
10438 then
10442 -- If the Operand Etype is Universal_Fixed, then the conversion is
10443 -- never redundant. We need this check because by the time we have
10444 -- finished the rather complex transformation, the conversion looks
10445 -- redundant when it is not.
10450 -- If the operand is marked as Any_Fixed, then special processing is
10451 -- required. This is also a case where we suppress the test for a
10452 -- redundant conversion, since most certainly it is not redundant.
10457 -- Mixed-mode operation involving a literal. Context must be a fixed
10458 -- type which is applied to the literal subsequently.
10466 or else
10468 then
10469 -- Return if expression is ambiguous
10474 -- If nothing else, the available fixed type is Duration
10476 else
10480 -- Resolve the real operand with largest available precision
10484 else
10490 -- If the operand is a literal (it could be a non-static and
10491 -- illegal exponentiation) check whether the use of Duration
10492 -- is potentially inaccurate.
10497 then
10498 Error_Msg_N
10501 Error_Msg_N
10508 then
10511 else
10520 -- In SPARK, a type conversion between array types should be restricted
10521 -- to types which have matching static bounds.
10523 -- Protect call to Matching_Static_Array_Bounds to avoid costly
10524 -- operation if not needed.
10531 then
10532 Check_SPARK_05_Restriction
10536 -- In formal mode, the operand of an ancestor type conversion must be an
10537 -- object (not an expression).
10545 then
10551 -- Note: we do the Eval_Type_Conversion call before applying the
10552 -- required checks for a subtype conversion. This is important, since
10553 -- both are prepared under certain circumstances to change the type
10554 -- conversion to a constraint error node, but in the case of
10555 -- Eval_Type_Conversion this may reflect an illegality in the static
10556 -- case, and we would miss the illegality (getting only a warning
10557 -- message), if we applied the type conversion checks first.
10561 -- Even when evaluation is not possible, we may be able to simplify the
10562 -- conversion or its expression. This needs to be done before applying
10563 -- checks, since otherwise the checks may use the original expression
10564 -- and defeat the simplifications. This is specifically the case for
10565 -- elimination of the floating-point Truncation attribute in
10566 -- float-to-int conversions.
10570 -- If after evaluation we still have a type conversion, then we may need
10571 -- to apply checks required for a subtype conversion.
10573 -- Skip these type conversion checks if universal fixed operands
10574 -- operands involved, since range checks are handled separately for
10575 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
10581 then
10585 -- Issue warning for conversion of simple object to its own type. We
10586 -- have to test the original nodes, since they may have been rewritten
10587 -- by various optimizations.
10591 -- Here we test for a redundant conversion if the warning mode is
10592 -- active (and was not locally reset), and we have a type conversion
10593 -- from source not appearing in a generic instance.
10595 if Test_Redundant
10598 and then not In_Instance
10599 then
10603 -- If the node is part of a larger expression, the Target_Type
10604 -- may not be the original type of the node if the context is a
10605 -- condition. Recover original type to see if conversion is needed.
10609 then
10613 -- If we have an entity name, then give the warning if the entity
10614 -- is the right type, or if it is a loop parameter covered by the
10615 -- original type (that's needed because loop parameters have an
10616 -- odd subtype coming from the bounds).
10619 and then
10621 or else
10625 -- If not an entity, then type of expression must match
10628 then
10629 -- One more check, do not give warning if the analyzed conversion
10630 -- has an expression with non-static bounds, and the bounds of the
10631 -- target are static. This avoids junk warnings in cases where the
10632 -- conversion is necessary to establish staticness, for example in
10633 -- a case statement.
10637 then
10640 -- Finally, if this type conversion occurs in a context requiring
10641 -- a prefix, and the expression is a qualified expression then the
10642 -- type conversion is not redundant, since a qualified expression
10643 -- is not a prefix, whereas a type conversion is. For example, "X
10644 -- := T'(Funx(...)).Y;" is illegal because a selected component
10645 -- requires a prefix, but a type conversion makes it legal: "X :=
10646 -- T(T'(Funx(...))).Y;"
10648 -- In Ada 2012, a qualified expression is a name, so this idiom is
10649 -- no longer needed, but we still suppress the warning because it
10650 -- seems unfriendly for warnings to pop up when you switch to the
10651 -- newer language version.
10655 N_Indexed_Component,
10656 N_Selected_Component,
10657 N_Slice,
10658 N_Explicit_Dereference)
10659 then
10662 -- Never warn on conversion to Long_Long_Integer'Base since
10663 -- that is most likely an artifact of the extended overflow
10664 -- checking and comes from complex expanded code.
10669 -- Here we give the redundant conversion warning. If it is an
10670 -- entity, give the name of the entity in the message. If not,
10671 -- just mention the expression.
10673 -- Shoudn't we test Warn_On_Redundant_Constructs here ???
10675 else
10678 Error_Msg_NE -- CODEFIX
10681 else
10682 Error_Msg_NE
10690 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
10691 -- No need to perform any interface conversion if the type of the
10692 -- expression coincides with the target type.
10695 and then Expander_Active
10697 then
10698 declare
10702 begin
10703 -- If the type of the operand is a limited view, use the non-
10704 -- limited view when available.
10709 then
10725 -- Conversion from interface type
10729 -- Ada 2005 (AI-217): Handle entities from limited views
10733 Error_Msg_NE -- CODEFIX
10736 Error_Msg_N
10738 N);
10741 and then not
10744 then
10746 Error_Msg_NE -- CODEFIX
10749 Error_Msg_N
10751 N);
10753 else
10757 -- Conversion to interface type
10761 -- Handle subtypes
10768 or else Interface_Present_In_Ancestor
10771 then
10773 else
10776 Error_Msg_N
10784 -- Ada 2012: if target type has predicates, the result requires a
10785 -- predicate check. If the context is a call to another predicate
10786 -- check we must prevent infinite recursion.
10792 or else
10794 then
10797 else
10802 -- If at this stage we have a real to integer conversion, make sure
10803 -- that the Do_Range_Check flag is set, because such conversions in
10804 -- general need a range check. We only need this if expansion is off
10805 -- or we are in GNATProve mode.
10811 then
10816 ----------------------
10817 -- Resolve_Unary_Op --
10818 ----------------------
10827 begin
10830 Check_SPARK_05_Restriction
10834 -- Deal with intrinsic unary operators
10840 then
10845 -- Deal with universal cases
10848 or else
10850 then
10857 -- Generate warning for expressions like abs (x mod 2)
10859 if Warn_On_Redundant_Constructs
10861 then
10865 Error_Msg_N -- CODEFIX
10870 -- Deal with reference generation
10877 -- Set overflow checking bit. Much cleverer code needed here eventually
10878 -- and perhaps the Resolve routines should be separated for the various
10879 -- arithmetic operations, since they will need different processing ???
10887 -- Generate warning for expressions like -5 mod 3 for integers. No need
10888 -- to worry in the floating-point case, since parens do not affect the
10889 -- result so there is no point in giving in a warning.
10891 declare
10900 begin
10901 if Warn_On_Questionable_Missing_Parens
10905 then
10908 -- We are looking for cases where the right operand is not
10909 -- parenthesized, and is a binary operator, multiply, divide, or
10910 -- mod. These are the cases where the grouping can affect results.
10914 then
10915 -- For mod, we always give the warning, since the value is
10916 -- affected by the parenthesization (e.g. (-5) mod 315 /=
10917 -- -(5 mod 315)). But for the other cases, the only concern is
10918 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
10919 -- overflows, but (-2) * 64 does not). So we try to give the
10920 -- message only when overflow is possible.
10924 then
10929 else
10935 else
10939 -- Note that the test below is deliberately excluding the
10940 -- largest negative number, since that is a potentially
10941 -- troublesome case (e.g. -2 * x, where the result is the
10942 -- largest negative integer has an overflow with 2 * x).
10949 -- For the multiplication case, the only case we have to worry
10950 -- about is when (-a)*b is exactly the largest negative number
10951 -- so that -(a*b) can cause overflow. This can only happen if
10952 -- a is a power of 2, and more generally if any operand is a
10953 -- constant that is not a power of 2, then the parentheses
10954 -- cannot affect whether overflow occurs. We only bother to
10955 -- test the left most operand
10957 -- Loop looking at left operands for one that has known value
10964 -- Operand value of 0 or 1 skips warning
10969 -- Otherwise check power of 2, if power of 2, warn, if
10970 -- anything else, skip warning.
10972 else
10976 else
10985 -- Keep looking at left operands
10990 -- For rem or "/" we can only have a problematic situation
10991 -- if the divisor has a value of minus one or one. Otherwise
10992 -- overflow is impossible (divisor > 1) or we have a case of
10993 -- division by zero in any case.
10998 then
11002 -- If we fall through warning should be issued
11004 -- Shouldn't we test Warn_On_Questionable_Missing_Parens ???
11006 Error_Msg_N
11013 ----------------------------------
11014 -- Resolve_Unchecked_Expression --
11015 ----------------------------------
11017 procedure Resolve_Unchecked_Expression
11020 is
11021 begin
11026 ---------------------------------------
11027 -- Resolve_Unchecked_Type_Conversion --
11028 ---------------------------------------
11030 procedure Resolve_Unchecked_Type_Conversion
11033 is
11039 begin
11040 -- Resolve operand using its own type
11044 -- In an inlined context, the unchecked conversion may be applied
11045 -- to a literal, in which case its type is the type of the context.
11046 -- (In other contexts conversions cannot apply to literals).
11048 if In_Inlined_Body
11052 then
11060 ------------------------------
11061 -- Rewrite_Operator_As_Call --
11062 ------------------------------
11069 begin
11076 New_N :=
11087 ------------------------------
11088 -- Rewrite_Renamed_Operator --
11089 ------------------------------
11091 procedure Rewrite_Renamed_Operator
11095 is
11100 begin
11101 -- Do not perform this transformation within a pre/postcondition,
11102 -- because the expression will be re-analyzed, and the transformation
11103 -- might affect the visibility of the operator, e.g. in an instance.
11109 -- Rewrite the operator node using the real operator, not its renaming.
11110 -- Exclude user-defined intrinsic operations of the same name, which are
11111 -- treated separately and rewritten as calls.
11120 -- Indicate that both the original entity and its renaming are
11121 -- referenced at this point.
11132 -- If the context type is private, add the appropriate conversions so
11133 -- that the operator is applied to the full view. This is done in the
11134 -- routines that resolve intrinsic operators.
11138 then
11140 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
11141 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
11154 -- Operator renames a user-defined operator of the same name. Use the
11155 -- original operator in the node, which is the one Gigi knows about.
11162 -----------------------
11163 -- Set_Slice_Subtype --
11164 -----------------------
11166 -- Build an implicit subtype declaration to represent the type delivered by
11167 -- the slice. This is an abbreviated version of an array subtype. We define
11168 -- an index subtype for the slice, using either the subtype name or the
11169 -- discrete range of the slice. To be consistent with index usage elsewhere
11170 -- we create a list header to hold the single index. This list is not
11171 -- otherwise attached to the syntax tree.
11182 begin
11188 else
11189 -- We force the evaluation of a range. This is definitely needed in
11190 -- the renamed case, and seems safer to do unconditionally. Note in
11191 -- any case that since we will create and insert an Itype referring
11192 -- to this range, we must make sure any side effect removal actions
11193 -- are inserted before the Itype definition.
11199 -- If the discrete range is given by a subtype indication, the
11200 -- type of the slice is the base of the subtype mark.
11203 declare
11205 begin
11214 -- Take a new copy of Drange (where bounds have been rewritten to
11215 -- reference side-effect-free names). Using a separate tree ensures
11216 -- that further expansion (e.g. while rewriting a slice assignment
11217 -- into a FOR loop) does not attempt to remove side effects on the
11218 -- bounds again (which would cause the bounds in the index subtype
11219 -- definition to refer to temporaries before they are defined) (the
11220 -- reason is that some names are considered side effect free here
11221 -- for the subtype, but not in the context of a loop iteration
11222 -- scheme).
11243 -- The Etype of the existing Slice node is reset to this slice subtype.
11244 -- Its bounds are obtained from its first index.
11248 -- For packed slice subtypes, freeze immediately (except in the case of
11249 -- being in a "spec expression" where we never freeze when we first see
11250 -- the expression).
11255 -- For all other cases insert an itype reference in the slice's actions
11256 -- so that the itype is frozen at the proper place in the tree (i.e. at
11257 -- the point where actions for the slice are analyzed). Note that this
11258 -- is different from freezing the itype immediately, which might be
11259 -- premature (e.g. if the slice is within a transient scope). This needs
11260 -- to be done only if expansion is enabled.
11267 --------------------------------
11268 -- Set_String_Literal_Subtype --
11269 --------------------------------
11277 begin
11289 -- The low bound is set from the low bound of the corresponding index
11290 -- type. Note that we do not store the high bound in the string literal
11291 -- subtype, but it can be deduced if necessary from the length and the
11292 -- low bound.
11297 -- If the lower bound is not static we create a range for the string
11298 -- literal, using the index type and the known length of the literal.
11299 -- The index type is not necessarily Positive, so the upper bound is
11300 -- computed as T'Val (T'Pos (Low_Bound) + L - 1).
11302 else
11303 declare
11309 Prefix =>
11313 Left_Opnd =>
11316 Prefix =>
11318 Expressions =>
11320 Right_Opnd =>
11329 begin
11331 Set_String_Literal_Low_Bound
11334 else
11335 -- If the index type is an enumeration type, build bounds
11336 -- expression with attributes.
11338 Set_String_Literal_Low_Bound
11342 Prefix =>
11349 -- Build bona fide subtype for the string, and wrap it in an
11350 -- unchecked conversion, because the backend expects the
11351 -- String_Literal_Subtype to have a static lower bound.
11353 Index_Subtype :=
11360 -- In the context, the Index_Type may already have a constraint,
11361 -- so use common base type on string subtype. The base type may
11362 -- be used when generating attributes of the string, for example
11363 -- in the context of a slice assignment.
11388 ------------------------------
11389 -- Simplify_Type_Conversion --
11390 ------------------------------
11393 begin
11395 declare
11400 begin
11401 -- Special processing if the conversion is the expression of a
11402 -- Rounding or Truncation attribute reference. In this case we
11403 -- replace:
11405 -- ityp (ftyp'Rounding (x)) or ityp (ftyp'Truncation (x))
11407 -- by
11409 -- ityp (x)
11411 -- with the Float_Truncate flag set to False or True respectively,
11412 -- which is more efficient.
11415 and then
11421 Name_Truncation)
11422 then
11423 declare
11426 begin
11436 -----------------------------
11437 -- Unique_Fixed_Point_Type --
11438 -----------------------------
11447 -- Give error messages for true ambiguity. Messages are posted on node
11448 -- N, and entities T1, T2 are the possible interpretations.
11450 -----------------------
11451 -- Fixed_Point_Error --
11452 -----------------------
11455 begin
11461 -- Start of processing for Unique_Fixed_Point_Type
11463 begin
11464 -- The operations on Duration are visible, so Duration is always a
11465 -- possible interpretation.
11469 -- Look for fixed-point types in enclosing scopes
11478 then
11480 Fixed_Point_Error;
11482 else
11493 -- Look for visible fixed type declarations in the context
11504 then
11506 Fixed_Point_Error;
11508 else
11521 Error_Msg_NE
11523 else
11524 Error_Msg_NE
11531 ----------------------
11532 -- Valid_Conversion --
11533 ----------------------
11535 function Valid_Conversion
11540 is
11545 function Conversion_Check
11548 -- Little routine to post Msg if Valid is False, returns Valid value
11551 -- If Report_Errs, then calls Errout.Error_Msg_N with its arguments
11553 procedure Conversion_Error_NE
11557 -- If Report_Errs, then calls Errout.Error_Msg_NE with its arguments
11559 function Valid_Tagged_Conversion
11562 -- Specifically test for validity of tagged conversions
11565 -- Check index and component conformance, and accessibility levels if
11566 -- the component types are anonymous access types (Ada 2005).
11568 ----------------------
11569 -- Conversion_Check --
11570 ----------------------
11572 function Conversion_Check
11575 is
11576 begin
11577 if not Valid
11579 -- A generic unit has already been analyzed and we have verified
11580 -- that a particular conversion is OK in that context. Since the
11581 -- instance is reanalyzed without relying on the relationships
11582 -- established during the analysis of the generic, it is possible
11583 -- to end up with inconsistent views of private types. Do not emit
11584 -- the error message in such cases. The rest of the machinery in
11585 -- Valid_Conversion still ensures the proper compatibility of
11586 -- target and operand types.
11588 and then not In_Instance
11589 then
11596 ------------------------
11597 -- Conversion_Error_N --
11598 ------------------------
11601 begin
11607 -------------------------
11608 -- Conversion_Error_NE --
11609 -------------------------
11611 procedure Conversion_Error_NE
11615 is
11616 begin
11622 ----------------------------
11623 -- Valid_Array_Conversion --
11624 ----------------------------
11627 is
11642 begin
11643 -- Error if wrong number of dimensions
11645 if
11647 then
11648 Conversion_Error_N
11652 -- Number of dimensions matches
11654 else
11655 -- Loop through indexes of the two arrays
11663 -- Error if index types are incompatible
11669 then
11670 Conversion_Error_N
11672 Operand);
11680 -- If component types have same base type, all set
11685 -- Here if base types of components are not the same. The only
11686 -- time this is allowed is if we have anonymous access types.
11688 -- The conversion of arrays of anonymous access types can lead
11689 -- to dangling pointers. AI-392 formalizes the accessibility
11690 -- checks that must be applied to such conversions to prevent
11691 -- out-of-scope references.
11693 elsif Ekind_In
11695 E_Anonymous_Access_Subprogram_Type)
11697 and then
11699 then
11702 then
11705 Conversion_Error_N
11715 -- Conversion not allowed because of accessibility levels
11717 else
11718 Conversion_Error_N
11724 else
11728 -- All other cases where component base types do not match
11730 else
11731 Conversion_Error_N
11733 Operand);
11737 -- Check that component subtypes statically match. For numeric
11738 -- types this means that both must be either constrained or
11739 -- unconstrained. For enumeration types the bounds must match.
11740 -- All of this is checked in Subtypes_Statically_Match.
11742 if not Subtypes_Statically_Match
11744 then
11745 Conversion_Error_N
11754 -----------------------------
11755 -- Valid_Tagged_Conversion --
11756 -----------------------------
11758 function Valid_Tagged_Conversion
11761 is
11762 begin
11763 -- Upward conversions are allowed (RM 4.6(22))
11767 then
11770 -- Downward conversion are allowed if the operand is class-wide
11771 -- (RM 4.6(23)).
11775 then
11780 then
11781 return
11785 -- Ada 2005 (AI-251): The conversion to/from interface types is
11786 -- always valid
11791 -- If the operand is a class-wide type obtained through a limited_
11792 -- with clause, and the context includes the non-limited view, use
11793 -- it to determine whether the conversion is legal.
11799 then
11804 then
11807 else
11808 Conversion_Error_NE
11815 -- Start of processing for Valid_Conversion
11817 begin
11821 declare
11829 begin
11830 -- Remove procedure calls, which syntactically cannot appear in
11831 -- this context, but which cannot be removed by type checking,
11832 -- because the context does not impose a type.
11834 -- The node may be labelled overloaded, but still contain only one
11835 -- interpretation because others were discarded earlier. If this
11836 -- is the case, retain the single interpretation if legal.
11844 then
11845 -- More than one candidate interpretation is available
11853 -- When compiling for a system where Address is of a visible
11854 -- integer type, spurious ambiguities can be produced when
11855 -- arithmetic operations have a literal operand and return
11856 -- System.Address or a descendant of it. These ambiguities
11857 -- are usually resolved by the context, but for conversions
11858 -- there is no context type and the removal of the spurious
11859 -- operations must be done explicitly here.
11861 if not Address_Is_Private
11863 then
11888 Conversion_Error_N
11891 -- If the interpretation involves a standard operator, use
11892 -- the location of the type, which may be user-defined.
11896 else
11900 Conversion_Error_N -- CODEFIX
11905 else
11909 Conversion_Error_N -- CODEFIX
11921 -- Deal with conversion of integer type to address if the pragma
11922 -- Allow_Integer_Address is in effect. We convert the conversion to
11923 -- an unchecked conversion in this case and we are all done.
11931 -- If we are within a child unit, check whether the type of the
11932 -- expression has an ancestor in a parent unit, in which case it
11933 -- belongs to its derivation class even if the ancestor is private.
11934 -- See RM 7.3.1 (5.2/3).
11938 -- Numeric types
11942 -- A universal fixed expression can be converted to any numeric type
11947 -- Also no need to check when in an instance or inlined body, because
11948 -- the legality has been established when the template was analyzed.
11949 -- Furthermore, numeric conversions may occur where only a private
11950 -- view of the operand type is visible at the instantiation point.
11951 -- This results in a spurious error if we check that the operand type
11952 -- is a numeric type.
11954 -- Note: in a previous version of this unit, the following tests were
11955 -- applied only for generated code (Comes_From_Source set to False),
11956 -- but in fact the test is required for source code as well, since
11957 -- this situation can arise in source code.
11962 -- Otherwise we need the conversion check
11964 else
11965 return Conversion_Check
11967 or else
11973 -- Array types
11979 then
11980 Conversion_Error_N
11984 else
11988 -- Ada 2005 (AI-251): Anonymous access types where target references an
11989 -- interface type.
11992 E_Anonymous_Access_Type)
11994 then
11995 -- Check the static accessibility rule of 4.6(17). Note that the
11996 -- check is not enforced when within an instance body, since the
11997 -- RM requires such cases to be caught at run time.
11999 -- If the operand is a rewriting of an allocator no check is needed
12000 -- because there are no accessibility issues.
12008 then
12009 -- In an instance, this is a run-time check, but one we know
12010 -- will fail, so generate an appropriate warning. The raise
12011 -- will be generated by Expand_N_Type_Conversion.
12015 Conversion_Error_N
12017 Operand);
12020 else
12021 Conversion_Error_N
12023 Operand);
12027 -- Special accessibility checks are needed in the case of access
12028 -- discriminants declared for a limited type.
12032 then
12033 -- When the operand is a selected access discriminant the check
12034 -- needs to be made against the level of the object denoted by
12035 -- the prefix of the selected name (Object_Access_Level handles
12036 -- checking the prefix of the operand for this case).
12041 then
12042 -- In an instance, this is a run-time check, but one we know
12043 -- will fail, so generate an appropriate warning. The raise
12044 -- will be generated by Expand_N_Type_Conversion.
12048 Conversion_Error_N
12053 -- Real error if not in instance body
12055 else
12056 Conversion_Error_N
12063 -- The case of a reference to an access discriminant from
12064 -- within a limited type declaration (which will appear as
12065 -- a discriminal) is always illegal because the level of the
12066 -- discriminant is considered to be deeper than any (nameable)
12067 -- access type.
12071 and then
12074 then
12075 Conversion_Error_N
12077 Operand);
12085 -- General and anonymous access types
12088 E_Anonymous_Access_Type)
12089 and then
12090 Conversion_Check
12092 and then not
12094 E_Access_Protected_Subprogram_Type),
12096 then
12099 then
12100 Conversion_Error_N
12105 -- Check the static accessibility rule of 4.6(17). Note that the
12106 -- check is not enforced when within an instance body, since the RM
12107 -- requires such cases to be caught at run time.
12112 N_Object_Declaration
12113 then
12114 -- Ada 2012 (AI05-0149): Perform legality checking on implicit
12115 -- conversions from an anonymous access type to a named general
12116 -- access type. Such conversions are not allowed in the case of
12117 -- access parameters and stand-alone objects of an anonymous
12118 -- access type. The implicit conversion case is recognized by
12119 -- testing that Comes_From_Source is False and that it's been
12120 -- rewritten. The Comes_From_Source test isn't sufficient because
12121 -- nodes in inlined calls to predefined library routines can have
12122 -- Comes_From_Source set to False. (Is there a better way to test
12123 -- for implicit conversions???)
12130 then
12133 -- Implicit conversions aren't allowed for objects of an
12134 -- anonymous access type, since such objects have nonstatic
12135 -- levels in Ada 2012.
12138 N_Object_Declaration
12139 then
12140 Conversion_Error_N
12145 -- Implicit conversions aren't allowed for anonymous access
12146 -- parameters. The "not Is_Local_Anonymous_Access_Type" test
12147 -- is done to exclude anonymous access results.
12151 N_Function_Specification,
12152 N_Procedure_Specification)
12153 then
12154 Conversion_Error_N
12159 -- This is a case where there's an enclosing object whose
12160 -- to which the "statically deeper than" relationship does
12161 -- not apply (such as an access discriminant selected from
12162 -- a dereference of an access parameter).
12166 then
12167 Conversion_Error_N
12172 -- In other cases, the level of the operand's type must be
12173 -- statically less deep than that of the target type, else
12174 -- implicit conversion is disallowed (by RM12-8.6(27.1/3)).
12178 then
12179 Conversion_Error_N
12188 then
12189 -- In an instance, this is a run-time check, but one we know
12190 -- will fail, so generate an appropriate warning. The raise
12191 -- will be generated by Expand_N_Type_Conversion.
12195 Conversion_Error_N
12197 Operand);
12200 -- If not in an instance body, this is a real error
12202 else
12203 -- Avoid generation of spurious error message
12206 Conversion_Error_N
12208 Operand);
12214 -- Special accessibility checks are needed in the case of access
12215 -- discriminants declared for a limited type.
12219 then
12220 -- When the operand is a selected access discriminant the check
12221 -- needs to be made against the level of the object denoted by
12222 -- the prefix of the selected name (Object_Access_Level handles
12223 -- checking the prefix of the operand for this case).
12228 then
12229 -- In an instance, this is a run-time check, but one we know
12230 -- will fail, so generate an appropriate warning. The raise
12231 -- will be generated by Expand_N_Type_Conversion.
12235 Conversion_Error_N
12240 -- If not in an instance body, this is a real error
12242 else
12243 Conversion_Error_N
12250 -- The case of a reference to an access discriminant from
12251 -- within a limited type declaration (which will appear as
12252 -- a discriminal) is always illegal because the level of the
12253 -- discriminant is considered to be deeper than any (nameable)
12254 -- access type.
12257 and then
12260 then
12261 Conversion_Error_N
12263 Operand);
12269 -- In the presence of limited_with clauses we have to use non-limited
12270 -- views, if available.
12274 -- Helper function to handle limited views
12276 --------------------------
12277 -- Full_Designated_Type --
12278 --------------------------
12283 begin
12284 -- Handle the limited view of a type
12289 then
12291 else
12296 -- Local Declarations
12304 -- Start of processing for Check_Limited
12306 begin
12310 else
12312 Conversion_Error_NE
12317 -- Ada 2005 AI-384: legality rule is symmetric in both
12318 -- designated types. The conversion is legal (with possible
12319 -- constraint check) if either designated type is
12320 -- unconstrained.
12323 or else
12325 and then
12328 then
12329 -- Special case, if Value_Size has been used to make the
12330 -- sizes different, the conversion is not allowed even
12331 -- though the subtypes statically match.
12336 then
12337 Conversion_Error_NE
12340 Conversion_Error_NE
12345 -- Normal case where conversion is allowed
12347 else
12351 else
12352 Error_Msg_NE
12360 -- Access to subprogram types. If the operand is an access parameter,
12361 -- the type has a deeper accessibility that any master, and cannot be
12362 -- assigned. We must make an exception if the conversion is part of an
12363 -- assignment and the target is the return object of an extended return
12364 -- statement, because in that case the accessibility check takes place
12365 -- after the return.
12369 -- Note: this test of Opnd_Type is there to prevent entering this
12370 -- branch in the case of a remote access to subprogram type, which
12371 -- is internally represented as an E_Record_Type.
12374 then
12378 and then
12382 then
12383 Conversion_Error_N
12385 Operand);
12386 Conversion_Error_N
12389 Operand);
12391 Error_Msg_NE
12396 -- Check that the designated types are subtype conformant
12402 -- Check the static accessibility rule of 4.6(20)
12406 then
12407 Conversion_Error_N
12409 Operand);
12411 -- Check that if the operand type is declared in a generic body,
12412 -- then the target type must be declared within that same body
12413 -- (enforces last sentence of 4.6(20)).
12416 declare
12422 begin
12429 Conversion_Error_N
12438 -- Remote access to subprogram types
12442 then
12443 -- It is valid to convert from one RAS type to another provided
12444 -- that their specification statically match.
12446 -- Note: at this point, remote access to subprogram types have been
12447 -- expanded to their E_Record_Type representation, and we need to
12448 -- go back to the original access type definition using the
12449 -- Corresponding_Remote_Type attribute in order to check that the
12450 -- designated profiles match.
12455 Check_Subtype_Conformant
12458 Old_Id =>
12460 Err_Loc =>
12461 N);
12464 -- If it was legal in the generic, it's legal in the instance
12469 -- If both are tagged types, check legality of view conversions
12472 and then
12474 then
12477 -- Types derived from the same root type are convertible
12482 -- In an instance or an inlined body, there may be inconsistent views of
12483 -- the same type, or of types derived from a common root.
12486 and then
12489 then
12492 -- Special check for common access type error case
12496 then
12498 Conversion_Error_NE -- CODEFIX
12502 -- Here we have a real conversion error
12504 else
12505 Conversion_Error_NE