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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) 1992-2013, 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 ------------------------------------------------------------------------------
83 -----------------------
84 -- Local Subprograms --
85 -----------------------
87 -- Second pass (top-down) type checking and overload resolution procedures
88 -- Typ is the type required by context. These procedures propagate the type
89 -- information recursively to the descendants of N. If the node is not
90 -- overloaded, its Etype is established in the first pass. If overloaded,
91 -- the Resolve routines set the correct type. For arith. operators, the
92 -- Etype is the base type of the context.
94 -- Note that Resolve_Attribute is separated off in Sem_Attr
96 function Bad_Unordered_Enumeration_Reference
99 -- Node N contains a potentially dubious reference to type T, either an
100 -- explicit comparison, or an explicit range. This function returns True
101 -- if the type T is an enumeration type for which No pragma Order has been
102 -- given, and the reference N is not in the same extended source unit as
103 -- the declaration of T.
106 -- Enforce the restrictions on the use of discriminants when constraining
107 -- a component of a discriminated type (record or concurrent type).
110 -- Given a node for an operator associated with type T, check that
111 -- the operator is visible. Operators all of whose operands are
112 -- universal must be checked for visibility during resolution
113 -- because their type is not determinable based on their operands.
115 procedure Check_Fully_Declared_Prefix
118 -- Check that the type of the prefix of a dereference is not incomplete
121 -- Given a call node, N, which is known to occur immediately within the
122 -- subprogram being called, determines whether it is a detectable case of
123 -- an infinite recursion, and if so, outputs appropriate messages. Returns
124 -- True if an infinite recursion is detected, and False otherwise.
127 -- If the type of the object being initialized uses the secondary stack
128 -- directly or indirectly, create a transient scope for the call to the
129 -- init proc. This is because we do not create transient scopes for the
130 -- initialization of individual components within the init proc itself.
131 -- Could be optimized away perhaps?
134 -- N is the node for a logical operator. If the operator is predefined, and
135 -- the root type of the operands is Standard.Boolean, then a check is made
136 -- for restriction No_Direct_Boolean_Operators. This procedure also handles
137 -- the style check for Style_Check_Boolean_And_Or.
140 -- Determine whether E is an access type declared by an access declaration,
141 -- and not an (anonymous) allocator type.
144 -- Utility to check whether the entity for an operator is a predefined
145 -- operator, in which case the expression is left as an operator in the
146 -- tree (else it is rewritten into a call). An instance of an intrinsic
147 -- conversion operation may be given an operator name, but is not treated
148 -- like an operator. Note that an operator that is an imported back-end
149 -- builtin has convention Intrinsic, but is expected to be rewritten into
150 -- a call, so such an operator is not treated as predefined by this
151 -- predicate.
154 -- If a default expression in entry call N depends on the discriminants
155 -- of the task, it must be replaced with a reference to the discriminant
156 -- of the task being called.
158 procedure Resolve_Op_Concat_Arg
163 -- Internal procedure for Resolve_Op_Concat to resolve one operand of
164 -- concatenation operator. The operand is either of the array type or of
165 -- the component type. If the operand is an aggregate, and the component
166 -- type is composite, this is ambiguous if component type has aggregates.
169 -- Does the first part of the work of Resolve_Op_Concat
172 -- Does the "rest" of the work of Resolve_Op_Concat, after the left operand
173 -- has been resolved. See Resolve_Op_Concat for details.
210 function Operator_Kind
213 -- Utility to map the name of an operator into the corresponding Node. Used
214 -- by other node rewriting procedures.
217 -- Resolve actuals of call, and add default expressions for missing ones.
218 -- N is the Node_Id for the subprogram call, and Nam is the entity of the
219 -- called subprogram.
222 -- Called from Resolve_Call, when the prefix denotes an entry or element
223 -- of entry family. Actuals are resolved as for subprograms, and the node
224 -- is rebuilt as an entry call. Also called for protected operations. Typ
225 -- is the context type, which is used when the operation is a protected
226 -- function with no arguments, and the return value is indexed.
229 -- A call to a user-defined intrinsic operator is rewritten as a call to
230 -- the corresponding predefined operator, with suitable conversions. Note
231 -- that this applies only for intrinsic operators that denote predefined
232 -- operators, not ones that are intrinsic imports of back-end builtins.
235 -- Ditto, for unary operators (arithmetic ones and "not" on signed
236 -- integer types for VMS).
239 -- If an operator node resolves to a call to a user-defined operator,
240 -- rewrite the node as a function call.
242 procedure Make_Call_Into_Operator
246 -- Inverse transformation: if an operator is given in functional notation,
247 -- then after resolving the node, transform into an operator node, so
248 -- that operands are resolved properly. Recall that predefined operators
249 -- do not have a full signature and special resolution rules apply.
251 procedure Rewrite_Renamed_Operator
255 -- An operator can rename another, e.g. in an instantiation. In that
256 -- case, the proper operator node must be constructed and resolved.
259 -- The String_Literal_Subtype is built for all strings that are not
260 -- operands of a static concatenation operation. If the argument is
261 -- not a N_String_Literal node, then the call has no effect.
264 -- Build subtype of array type, with the range specified by the slice
267 -- Called after N has been resolved and evaluated, but before range checks
268 -- have been applied. Currently simplifies a combination of floating-point
269 -- to integer conversion and Truncation attribute.
272 -- A universal_fixed expression in an universal context is unambiguous if
273 -- there is only one applicable fixed point type. Determining whether there
274 -- is only one requires a search over all visible entities, and happens
275 -- only in very pathological cases (see 6115-006).
277 -------------------------
278 -- Ambiguous_Character --
279 -------------------------
284 begin
288 -- First the ones in Standard
293 -- Include Wide_Wide_Character in Ada 2005 mode
299 -- Now any other types that match
309 -------------------------
310 -- Analyze_And_Resolve --
311 -------------------------
314 begin
320 begin
325 -- Versions with check(s) suppressed
327 procedure Analyze_And_Resolve
331 is
334 begin
336 declare
338 begin
344 else
345 declare
347 begin
355 and then Scope_Is_Transient
356 then
357 -- This can only happen if a transient scope was created for an inner
358 -- expression, which will be removed upon completion of the analysis
359 -- of an enclosing construct. The transient scope must have the
360 -- suppress status of the enclosing environment, not of this Analyze
361 -- call.
364 Scope_Suppress;
368 procedure Analyze_And_Resolve
371 is
374 begin
376 declare
378 begin
384 else
385 declare
387 begin
396 Scope_Suppress;
400 ----------------------------------------
401 -- Bad_Unordered_Enumeration_Reference --
402 ----------------------------------------
404 function Bad_Unordered_Enumeration_Reference
407 is
408 begin
411 and then Warn_On_Unordered_Enumeration_Type
416 ----------------------------
417 -- Check_Discriminant_Use --
418 ----------------------------
426 begin
427 -- Any use in a spec-expression is legal
434 -- Discriminant cannot be used to constrain a scalar type
441 then
446 -- The following check catches the unusual case where a
447 -- discriminant appears within an index constraint that is part of
448 -- a larger expression within a constraint on a component, e.g. "C
449 -- : Int range 1 .. F (new A(1 .. D))". For now we only check case
450 -- of record components, and note that a similar check should also
451 -- apply in the case of discriminant constraints below. ???
453 -- Note that the check for N_Subtype_Declaration below is to
454 -- detect the valid use of discriminants in the constraints of a
455 -- subtype declaration when this subtype declaration appears
456 -- inside the scope of a record type (which is syntactically
457 -- illegal, but which may be created as part of derived type
458 -- processing for records). See Sem_Ch3.Build_Derived_Record_Type
459 -- for more info.
463 and then not
465 and then
467 N_Subtype_Declaration)
469 then
470 Error_Msg_N
475 -- Detect a common error:
477 -- type R (D : Positive := 100) is record
478 -- Name : String (1 .. D);
479 -- end record;
481 -- The default value causes an object of type R to be allocated
482 -- with room for Positive'Last characters. The RM does not mandate
483 -- the allocation of the maximum size, but that is what GNAT does
484 -- so we should warn the programmer that there is a problem.
493 -- Return True if type T has a large enough range that any
494 -- array whose index type covered the whole range of the type
495 -- would likely raise Storage_Error.
497 ------------------------
498 -- Large_Storage_Type --
499 ------------------------
502 begin
503 -- The type is considered large if its bounds are known at
504 -- compile time and if it requires at least as many bits as
505 -- a Positive to store the possible values.
509 and then
514 -- Start of processing for Check_Large
516 begin
517 -- Check that the Disc has a large range
523 -- If the enclosing type is limited, we allocate only the
524 -- default value, not the maximum, and there is no need for
525 -- a warning.
531 -- Check that it is the high bound
535 then
539 -- Check the array allows a large range at this bound. First
540 -- find the array
554 -- Next, find the dimension
562 loop
571 -- Now, check the dimension has a large range
577 -- Warn about the danger
579 Error_Msg_N
589 -- Legal case is in index or discriminant constraint
592 N_Discriminant_Association)
593 then
595 Error_Msg_N
600 then
601 Error_Msg_N
607 -- Otherwise, context is an expression. It should not be within (i.e. a
608 -- subexpression of) a constraint for a component.
610 else
614 N_Subtype_Indication,
615 N_Entry_Declaration)
616 loop
622 -- If the discriminant is used in an expression that is a bound of a
623 -- scalar type, an Itype is created and the bounds are attached to
624 -- its range, not to the original subtype indication. Such use is of
625 -- course a double fault.
629 N_Derived_Type_Definition)
632 -- The constraint itself may be given by a subtype indication,
633 -- rather than by a more common discrete range.
636 and then
640 then
641 Error_Msg_N
647 --------------------------------
648 -- Check_For_Visible_Operator --
649 --------------------------------
652 begin
654 Error_Msg_NE -- CODEFIX
656 Error_Msg_N -- CODEFIX
661 ----------------------------------
662 -- Check_Fully_Declared_Prefix --
663 ----------------------------------
665 procedure Check_Fully_Declared_Prefix
668 is
669 begin
670 -- Check that the designated type of the prefix of a dereference is
671 -- not an incomplete type. This cannot be done unconditionally, because
672 -- dereferences of private types are legal in default expressions. This
673 -- case is taken care of in Check_Fully_Declared, called below. There
674 -- are also 2005 cases where it is legal for the prefix to be unfrozen.
676 -- This consideration also applies to similar checks for allocators,
677 -- qualified expressions, and type conversions.
679 -- An additional exception concerns other per-object expressions that
680 -- are not directly related to component declarations, in particular
681 -- representation pragmas for tasks. These will be per-object
682 -- expressions if they depend on discriminants or some global entity.
683 -- If the task has access discriminants, the designated type may be
684 -- incomplete at the point the expression is resolved. This resolution
685 -- takes place within the body of the initialization procedure, where
686 -- the discriminant is replaced by its discriminal.
690 then
693 -- Ada 2005 (AI-326): Tagged incomplete types allowed. The wrong usages
694 -- are handled by Analyze_Access_Attribute, Analyze_Assignment,
695 -- Analyze_Object_Renaming, and Freeze_Entity.
701 E_Incomplete_Type
703 then
705 else
710 ------------------------------
711 -- Check_Infinite_Recursion --
712 ------------------------------
719 -- Check whether list of actuals is identical to list of formals of
720 -- called function (which is also the enclosing scope).
722 ------------------------
723 -- Same_Argument_List --
724 ------------------------
731 begin
734 else
743 then
754 -- Start of processing for Check_Infinite_Recursion
756 begin
757 -- Special case, if this is a procedure call and is a call to the
758 -- current procedure with the same argument list, then this is for
759 -- sure an infinite recursion and we insert a call to raise SE.
763 and then Same_Argument_List
764 then
765 declare
767 begin
771 then
782 -- If not that special case, search up tree, quitting if we reach a
783 -- construct (e.g. a conditional) that tells us that this is not a
784 -- case for an infinite recursion warning.
787 loop
790 -- If no parent, then we were not inside a subprogram, this can for
791 -- example happen when processing certain pragmas in a spec. Just
792 -- return False in this case.
798 -- Done if we get to subprogram body, this is definitely an infinite
799 -- recursion case if we did not find anything to stop us.
803 -- If appearing in conditional, result is false
806 N_And_Then,
807 N_Case_Expression,
808 N_Case_Statement,
809 N_If_Expression,
810 N_If_Statement)
811 then
816 then
817 -- If the call is the expression of a return statement and the
818 -- actuals are identical to the formals, it's worth a warning.
819 -- However, we skip this if there is an immediately preceding
820 -- raise statement, since the call is never executed.
822 -- Furthermore, this corresponds to a common idiom:
824 -- function F (L : Thing) return Boolean is
825 -- begin
826 -- raise Program_Error;
827 -- return F (L);
828 -- end F;
830 -- for generating a stub function
833 and then Same_Argument_List
834 then
837 -- OK, return statement is in a statement list, look for raise
839 declare
842 begin
843 -- Skip past N_Freeze_Entity nodes generated by expansion
848 loop
852 -- If no raise statement, give warning. We look at the
853 -- original node, because in the case of "raise ... with
854 -- ...", the node has been transformed into a call.
857 and then
865 else
876 -------------------------------
877 -- Check_Initialization_Call --
878 -------------------------------
884 -- Check whether the creation of an object of the type will involve
885 -- use of the secondary stack. If T is a record type, this is true
886 -- if the expression for some component uses the secondary stack, e.g.
887 -- through a call to a function that returns an unconstrained value.
888 -- False if T is controlled, because cleanups occur elsewhere.
890 -------------
891 -- Uses_SS --
892 -------------
899 begin
900 -- Normally we want to use the underlying type, but if it's not set
901 -- then continue with T.
918 then
919 -- The expression for a dynamic component may be rewritten
920 -- as a dereference, so retrieve original node.
924 -- Return True if the expression is a call to a function
925 -- (including an attribute function such as Image, or a
926 -- user-defined operator) with a result that requires a
927 -- transient scope.
934 then
947 else
952 -- Start of processing for Check_Initialization_Call
954 begin
955 -- Establish a transient scope if the type needs it
962 ---------------------------------------
963 -- Check_No_Direct_Boolean_Operators --
964 ---------------------------------------
967 begin
970 then
971 -- Restriction only applies to original source code
983 ------------------------------
984 -- Check_Parameterless_Call --
985 ------------------------------
991 -- If the prefix is of an access_to_subprogram type, the node must be
992 -- rewritten as a call. Ditto if the prefix is overloaded and all its
993 -- interpretations are access to subprograms.
995 ---------------------------
996 -- Prefix_Is_Access_Subp --
997 ---------------------------
1003 begin
1004 -- If the context is an attribute reference that can apply to
1005 -- functions, this is never a parameterless call (RM 4.1.4(6)).
1009 Name_Code_Address,
1010 Name_Access)
1011 then
1016 return
1019 else
1024 then
1035 -- Start of processing for Check_Parameterless_Call
1037 begin
1038 -- Defend against junk stuff if errors already detected
1045 then
1052 -- If the context expects a value, and the name is a procedure, this is
1053 -- most likely a missing 'Access. Don't try to resolve the parameterless
1054 -- call, error will be caught when the outer call is analyzed.
1059 and then
1061 N_Function_Call,
1062 N_Procedure_Call_Statement)
1063 then
1067 -- Rewrite as call if overloadable entity that is (or could be, in the
1068 -- overloaded case) a function call. If we know for sure that the entity
1069 -- is an enumeration literal, we do not rewrite it.
1071 -- If the entity is the name of an operator, it cannot be a call because
1072 -- operators cannot have default parameters. In this case, this must be
1073 -- a string whose contents coincide with an operator name. Set the kind
1074 -- of the node appropriately.
1082 -- Rewrite as call if it is an explicit dereference of an expression of
1083 -- a subprogram access type, and the subprogram type is not that of a
1084 -- procedure or entry.
1086 or else
1089 -- Rewrite as call if it is a selected component which is a function,
1090 -- this is the case of a call to a protected function (which may be
1091 -- overloaded with other protected operations).
1093 or else
1096 or else
1098 E_Procedure)
1101 -- If one of the above three conditions is met, rewrite as call. Apply
1102 -- the rewriting only once.
1104 then
1107 then
1109 -- This may be a prefixed call that was not fully analyzed, e.g.
1110 -- an actual in an instance.
1115 then
1125 -- If overloaded, overload set belongs to new copy
1129 -- Change node to parameterless function call (note that the
1130 -- Parameter_Associations associations field is left set to Empty,
1131 -- its normal default value since there are no parameters)
1149 -----------------------------
1150 -- Is_Definite_Access_Type --
1151 -----------------------------
1155 begin
1161 ----------------------
1162 -- Is_Predefined_Op --
1163 ----------------------
1166 begin
1167 -- Predefined operators are intrinsic subprograms
1173 -- A call to a back-end builtin is never a predefined operator
1184 -----------------------------
1185 -- Make_Call_Into_Operator --
1186 -----------------------------
1188 procedure Make_Call_Into_Operator
1192 is
1207 -- If the operand is not universal, and the operator is given by an
1208 -- expanded name, verify that the operand has an interpretation with a
1209 -- type defined in the given scope of the operator.
1212 -- Find a type of the given class in package Pack that contains the
1213 -- operator.
1215 ---------------------------
1216 -- Operand_Type_In_Scope --
1217 ---------------------------
1224 begin
1228 else
1242 ---------------
1243 -- Type_In_P --
1244 ---------------
1250 -- Verify that node is not part of the type declaration for the
1251 -- candidate type, which would otherwise be invisible.
1253 -------------
1254 -- In_Decl --
1255 -------------
1261 begin
1270 else
1273 loop
1276 else
1285 -- Start of processing for Type_In_P
1287 begin
1288 -- If the context type is declared in the prefix package, this is the
1289 -- desired base type.
1294 else
1298 and then not In_Decl
1299 then
1310 -- Start of processing for Make_Call_Into_Operator
1312 begin
1315 -- Binary operator
1325 -- Unary operator
1327 else
1333 -- If the operator is denoted by an expanded name, and the prefix is
1334 -- not Standard, but the operator is a predefined one whose scope is
1335 -- Standard, then this is an implicit_operator, inserted as an
1336 -- interpretation by the procedure of the same name. This procedure
1337 -- overestimates the presence of implicit operators, because it does
1338 -- not examine the type of the operands. Verify now that the operand
1339 -- type appears in the given scope. If right operand is universal,
1340 -- check the other operand. In the case of concatenation, either
1341 -- argument can be the component type, so check the type of the result.
1342 -- If both arguments are literals, look for a type of the right kind
1343 -- defined in the given scope. This elaborate nonsense is brought to
1344 -- you courtesy of b33302a. The type itself must be frozen, so we must
1345 -- find the type of the proper class in the given scope.
1347 -- A final wrinkle is the multiplication operator for fixed point types,
1348 -- which is defined in Standard only, and not in the scope of the
1349 -- fixed point type itself.
1354 -- If this is a package renaming, get renamed entity, which will be
1355 -- the scope of the operands if operaton is type-correct.
1361 -- If the entity being called is defined in the given package, it is
1362 -- a renaming of a predefined operator, and known to be legal.
1366 then
1369 -- Visibility does not need to be checked in an instance: if the
1370 -- operator was not visible in the generic it has been diagnosed
1371 -- already, else there is an implicit copy of it in the instance.
1379 then
1384 -- Ada 2005 AI-420: Predefined equality on Universal_Access is
1385 -- available.
1390 then
1393 else
1402 and then Is_Binary
1404 then
1410 -- Verify that the scope contains a type that corresponds to
1411 -- the given literal. Optimize the case where Pack is Standard.
1433 else
1442 else
1451 then
1454 -- If the type is defined elsewhere, and the operator is not
1455 -- defined in the given scope (by a renaming declaration, e.g.)
1456 -- then this is an error as well. If an extension of System is
1457 -- present, and the type may be defined there, Pack must be
1458 -- System itself.
1465 then
1468 else
1474 then
1481 Error_Msg_NE
1486 -- Detect a mismatch between the context type and the result type
1487 -- in the named package, which is otherwise not detected if the
1488 -- operands are universal. Check is only needed if source entity is
1489 -- an operator, not a function that renames an operator.
1496 and then not In_Instance
1497 then
1500 then
1501 -- Already checked above
1505 -- Operator may be defined in an extension of System
1509 then
1512 else
1513 -- Could we use Wrong_Type here??? (this would require setting
1514 -- Etype (N) to the actual type found where Typ was expected).
1525 else
1529 -- If this is a call to a function that renames a predefined equality,
1530 -- the renaming declaration provides a type that must be used to
1531 -- resolve the operands. This must be done now because resolution of
1532 -- the equality node will not resolve any remaining ambiguity, and it
1533 -- assumes that the first operand is not overloaded.
1538 then
1546 -- Do rewrite setting Comes_From_Source on the result if the original
1547 -- call came from source. Although it is not strictly the case that the
1548 -- operator as such comes from the source, logically it corresponds
1549 -- exactly to the function call in the source, so it should be marked
1550 -- this way (e.g. to make sure that validity checks work fine).
1552 declare
1554 begin
1559 -- If this is an arithmetic operator and the result type is private,
1560 -- the operands and the result must be wrapped in conversion to
1561 -- expose the underlying numeric type and expand the proper checks,
1562 -- e.g. on division.
1566 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
1567 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
1576 else
1580 -- If in ASIS_Mode, propagate operand types to original actuals of
1581 -- function call, which would otherwise not be fully resolved. If
1582 -- the call has already been constant-folded, nothing to do.
1586 Set_Parameter_Associations
1590 else
1591 Set_Parameter_Associations
1598 -------------------
1599 -- Operator_Kind --
1600 -------------------
1602 function Operator_Kind
1605 is
1608 begin
1609 -- Use CASE statement or array???
1646 else
1650 -- Unary operators
1652 else
1661 else
1669 ----------------------------
1670 -- Preanalyze_And_Resolve --
1671 ----------------------------
1676 begin
1680 -- Normally, we suppress all checks for this preanalysis. There is no
1681 -- point in processing them now, since they will be applied properly
1682 -- and in the proper location when the default expressions reanalyzed
1683 -- and reexpanded later on. We will also have more information at that
1684 -- point for possible suppression of individual checks.
1686 -- However, in SPARK mode, most expansion is suppressed, and this
1687 -- later reanalysis and reexpansion may not occur. SPARK mode does
1688 -- require the setting of checking flags for proof purposes, so we
1689 -- do the SPARK preanalysis without suppressing checks.
1691 -- This special handling for SPARK mode is required for example in the
1692 -- case of Ada 2012 constructs such as quantified expressions, which are
1693 -- expanded in two separate steps.
1697 else
1701 Expander_Mode_Restore;
1705 -- Version without context type
1710 begin
1717 Expander_Mode_Restore;
1721 ----------------------------------
1722 -- Replace_Actual_Discriminants --
1723 ----------------------------------
1730 -- Comment needed???
1732 -------------------
1733 -- Process_Discr --
1734 -------------------
1739 begin
1745 then
1761 -- Start of processing for Replace_Actual_Discriminants
1763 begin
1777 else
1782 -------------
1783 -- Resolve --
1784 -------------
1800 -- Determine whether a node comes from a predefined library unit or
1801 -- Standard.
1804 -- Try and fix up a literal so that it matches its expected type. New
1805 -- literals are manufactured if necessary to avoid cascaded errors.
1808 -- Return the current scope. Skip loop scopes created for the purpose of
1809 -- quantified expression analysis since those do not appear in the tree.
1812 -- Additional diagnostics when an ambiguous call has an ambiguous
1813 -- argument (typically a controlling actual).
1816 -- Called when attempt at resolving current expression fails
1818 ------------------------------------
1819 -- Comes_From_Predefined_Lib_Unit --
1820 -------------------------------------
1823 begin
1824 return
1826 or else Is_Predefined_File_Name
1830 --------------------
1831 -- Patch_Up_Value --
1832 --------------------
1835 begin
1852 then
1857 Char_Literal_Value =>
1873 --------------------------
1874 -- Proper_Current_Scope --
1875 --------------------------
1880 begin
1883 -- Skip a loop scope created for quantified expression analysis
1887 then
1889 else
1897 -------------------------------
1898 -- Report_Ambiguous_Argument --
1899 -------------------------------
1906 begin
1910 then
1913 -- Could use comments on what is going on here???
1921 else
1930 -----------------------
1931 -- Resolution_Failed --
1932 -----------------------
1935 begin
1941 -- The caller will return without calling the expander, so we need
1942 -- to set the analyzed flag. Note that it is fine to set Analyzed
1943 -- to True even if we are in the middle of a shallow analysis,
1944 -- (see the spec of sem for more details) since this is an error
1945 -- situation anyway, and there is no point in repeating the
1946 -- analysis later (indeed it won't work to repeat it later, since
1947 -- we haven't got a clear resolution of which entity is being
1948 -- referenced.)
1954 -- Start of processing for Resolve
1956 begin
1961 -- Access attribute on remote subprogram cannot be used for a non-remote
1962 -- access-to-subprogram type.
1966 Name_Unrestricted_Access,
1967 Name_Unchecked_Access)
1973 then
1974 Error_Msg_N
1980 -- If the context is a Remote_Access_To_Subprogram, access attributes
1981 -- must be resolved with the corresponding fat pointer. There is no need
1982 -- to check for the attribute name since the return type of an
1983 -- attribute is never a remote type.
1988 then
1989 declare
1997 begin
1998 -- Check that Typ is a remote access-to-subprogram type
2002 -- Prefix (N) must statically denote a remote subprogram
2003 -- declared in a package specification.
2007 Attr = Attribute_Unrestricted_Access
2008 then
2023 or else
2025 then
2027 Error_Msg_N
2029 N);
2032 -- If we are generating code in distributed mode, perform
2033 -- semantic checks against corresponding remote entities.
2035 if Full_Expander_Active
2037 then
2038 Check_Subtype_Conformant
2040 Old_Id => Designated_Type
2066 then
2071 -- Return if already analyzed
2078 -- A Raise_Expression takes its type from context. The Etype was set
2079 -- to Any_Type, reflecting the fact that the expression itself does
2080 -- not specify any possible interpretation. So we set the type to the
2081 -- resolution type here and now. We need to do this before Resolve sees
2082 -- the Any_Type value.
2087 -- Any other case of Any_Type as the Etype value means that we had
2088 -- a previous error.
2097 -- If not overloaded, then we know the type, and all that needs doing
2098 -- is to check that this type is compatible with the context.
2104 -- In the overloaded case, we must select the interpretation that
2105 -- is compatible with the context (i.e. the type passed to Resolve)
2107 else
2108 -- Loop through possible interpretations
2118 -- We are only interested in interpretations that are compatible
2119 -- with the expected type, any other interpretations are ignored.
2124 Write_Eol;
2127 else
2128 -- Skip the current interpretation if it is disabled by an
2129 -- abstract operator. This action is performed only when the
2130 -- type against which we are resolving is the same as the
2131 -- type of the interpretation.
2138 then
2146 -- First matching interpretation
2154 -- Matching interpretation that is not the first, maybe an
2155 -- error, but there are some cases where preference rules are
2156 -- used to choose between the two possibilities. These and
2157 -- some more obscure cases are handled in Disambiguate.
2159 else
2160 -- If the current statement is part of a predefined library
2161 -- unit, then all interpretations which come from user level
2162 -- packages should not be considered.
2164 if From_Lib
2166 then
2173 -- Disambiguation has succeeded. Skip the remaining
2174 -- interpretations.
2184 else
2185 -- Before we issue an ambiguity complaint, check for
2186 -- the case of a subprogram call where at least one
2187 -- of the arguments is Any_Type, and if so, suppress
2188 -- the message, since it is a cascaded error.
2191 declare
2195 begin
2207 Write_Eol;
2220 then
2225 then
2229 -- Not that special case, so issue message using the
2230 -- flag Ambiguous to control printing of the header
2231 -- message only at the start of an ambiguous set.
2236 then
2237 Error_Msg_N
2240 else
2241 Error_Msg_NE -- CODEFIX
2249 Error_Msg_N
2251 else
2252 Error_Msg_N -- CODEFIX
2258 then
2259 Report_Ambiguous_Argument;
2265 -- By default, the error message refers to the candidate
2266 -- interpretation. But if it is a predefined operator, it
2267 -- is implicitly declared at the declaration of the type
2268 -- of the operand. Recover the sloc of that declaration
2269 -- for the error message.
2275 Standard_Standard
2276 then
2281 then
2289 Standard_Standard
2290 then
2295 then
2299 -- If this is an indirect call, use the subprogram_type
2300 -- in the message, to have a meaningful location. Also
2301 -- indicate if this is an inherited operation, created
2302 -- by a type declaration.
2307 then
2309 Error_Msg_Sloc :=
2311 else
2318 then
2319 -- Special-case the message for universal_fixed
2320 -- operators, which are not declared with the type
2321 -- of the operand, but appear forever in Standard.
2325 then
2326 Error_Msg_N
2329 else
2330 Error_Msg_N
2334 elsif
2336 then
2337 Error_Msg_N
2339 else
2340 Error_Msg_N -- CODEFIX
2347 -- We have a matching interpretation, Expr_Type is the type
2348 -- from this interpretation, and Seen is the entity.
2350 -- For an operator, just set the entity name. The type will be
2351 -- set by the specific operator resolution routine.
2366 -- AI05-0139-2: Expression is overloaded because type has
2367 -- implicit dereference. If type matches context, no implicit
2368 -- dereference is involved.
2379 then
2382 -- For an explicit dereference, attribute reference, range,
2383 -- short-circuit form (which is not an operator node), or call
2384 -- with a name that is an explicit dereference, there is
2385 -- nothing to be done at this point.
2388 N_Attribute_Reference,
2389 N_And_Then,
2390 N_Indexed_Component,
2391 N_Or_Else,
2392 N_Range,
2393 N_Selected_Component,
2394 N_Slice)
2396 then
2399 -- For procedure or function calls, set the type of the name,
2400 -- and also the entity pointer for the prefix.
2404 then
2411 then
2416 -- For all other cases, just set the type of the Name
2418 else
2426 -- Move to next interpretation
2434 -- At this stage Found indicates whether or not an acceptable
2435 -- interpretation exists. If not, then we have an error, except that if
2436 -- the context is Any_Type as a result of some other error, then we
2437 -- suppress the error report.
2442 -- If type we are looking for is Void, then this is the procedure
2443 -- call case, and the error is simply that what we gave is not a
2444 -- procedure name (we think of procedure calls as expressions with
2445 -- types internally, but the user doesn't think of them this way!)
2449 -- Special case message if function used as a procedure
2454 then
2455 Error_Msg_NE
2459 -- Otherwise give general message (not clear what cases this
2460 -- covers, but no harm in providing for them!)
2462 else
2468 -- Otherwise we do have a subexpression with the wrong type
2470 -- Check for the case of an allocator which uses an access type
2471 -- instead of the designated type. This is a common error and we
2472 -- specialize the message, posting an error on the operand of the
2473 -- allocator, complaining that we expected the designated type of
2474 -- the allocator.
2480 then
2484 -- Check for view mismatch on Null in instances, for which the
2485 -- view-swapping mechanism has no identifier.
2491 then
2496 -- Check for an aggregate. Sometimes we can get bogus aggregates
2497 -- from misuse of parentheses, and we are about to complain about
2498 -- the aggregate without even looking inside it.
2500 -- Instead, if we have an aggregate of type Any_Composite, then
2501 -- analyze and resolve the component fields, and then only issue
2502 -- another message if we get no errors doing this (otherwise
2503 -- assume that the errors in the aggregate caused the problem).
2507 then
2508 -- Disable expansion in any case. If there is a type mismatch
2509 -- it may be fatal to try to expand the aggregate. The flag
2510 -- would otherwise be set to false when the error is posted.
2514 declare
2516 -- Check one aggregate, and set Found to True if we have a
2517 -- definite error in any of its elements
2520 -- Check one element of aggregate and set Found to True if
2521 -- we definitely have an error in the element.
2523 ----------------
2524 -- Check_Aggr --
2525 ----------------
2530 begin
2543 -- If this is a default-initialized component, then
2544 -- there is nothing to check. The box will be
2545 -- replaced by the appropriate call during late
2546 -- expansion.
2557 ----------------
2558 -- Check_Elmt --
2559 ----------------
2562 begin
2563 -- If we have a nested aggregate, go inside it (to
2564 -- attempt a naked analyze-resolve of the aggregate can
2565 -- cause undesirable cascaded errors). Do not resolve
2566 -- expression if it needs a type from context, as for
2567 -- integer * fixed expression.
2572 else
2577 then
2587 begin
2592 -- If an error message was issued already, Found got reset to
2593 -- True, so if it is still False, issue standard Wrong_Type msg.
2598 then
2599 declare
2601 begin
2607 -- Protected operation: retrieve operation name
2611 else
2616 Error_Msg_NE
2622 declare
2626 begin
2633 Error_Msg_NE
2639 else
2643 else
2649 Resolution_Failed;
2652 -- Test if we have more than one interpretation for the context
2655 Resolution_Failed;
2658 -- Only one intepretation
2660 else
2661 -- In Ada 2005, if we have something like "X : T := 2 + 2;", where
2662 -- the "+" on T is abstract, and the operands are of universal type,
2663 -- the above code will have (incorrectly) resolved the "+" to the
2664 -- universal one in Standard. Therefore check for this case and give
2665 -- an error. We can't do this earlier, because it would cause legal
2666 -- cases to get errors (when some other type has an abstract "+").
2672 then
2677 then
2678 Error_Msg_NE
2687 -- Here we have an acceptable interpretation for the context
2689 -- Propagate type information and normalize tree for various
2690 -- predefined operations. If the context only imposes a class of
2691 -- types, rather than a specific type, propagate the actual type
2692 -- downward.
2698 Typ = Any_Discrete
2699 then
2702 -- Any_Fixed is legal in a real context only if a specific fixed-
2703 -- point type is imposed. If Norman Cohen can be confused by this,
2704 -- it deserves a separate message.
2708 then
2715 -- A user-defined operator is transformed into a function call at
2716 -- this point, so that further processing knows that operators are
2717 -- really operators (i.e. are predefined operators). User-defined
2718 -- operators that are intrinsic are just renamings of the predefined
2719 -- ones, and need not be turned into calls either, but if they rename
2720 -- a different operator, we must transform the node accordingly.
2721 -- Instantiations of Unchecked_Conversion are intrinsic but are
2722 -- treated as functions, even if given an operator designator.
2727 then
2733 and then
2735 N_Subprogram_Renaming_Declaration
2736 then
2739 -- If the node is rewritten, it will be fully resolved in
2740 -- Rewrite_Renamed_Operator.
2750 when N_Aggregate => Resolve_Aggregate (N, Ctx_Type);
2752 when N_Allocator => Resolve_Allocator (N, Ctx_Type);
2754 when N_Short_Circuit
2755 => Resolve_Short_Circuit (N, Ctx_Type);
2757 when N_Attribute_Reference
2758 => Resolve_Attribute (N, Ctx_Type);
2760 when N_Case_Expression
2761 => Resolve_Case_Expression (N, Ctx_Type);
2763 when N_Character_Literal
2764 => Resolve_Character_Literal (N, Ctx_Type);
2766 when N_Expanded_Name
2767 => Resolve_Entity_Name (N, Ctx_Type);
2769 when N_Explicit_Dereference
2770 => Resolve_Explicit_Dereference (N, Ctx_Type);
2772 when N_Expression_With_Actions
2773 => Resolve_Expression_With_Actions (N, Ctx_Type);
2775 when N_Extension_Aggregate
2776 => Resolve_Extension_Aggregate (N, Ctx_Type);
2778 when N_Function_Call
2779 => Resolve_Call (N, Ctx_Type);
2781 when N_Identifier
2782 => Resolve_Entity_Name (N, Ctx_Type);
2784 when N_If_Expression
2785 => Resolve_If_Expression (N, Ctx_Type);
2787 when N_Indexed_Component
2788 => Resolve_Indexed_Component (N, Ctx_Type);
2790 when N_Integer_Literal
2791 => Resolve_Integer_Literal (N, Ctx_Type);
2793 when N_Membership_Test
2794 => Resolve_Membership_Op (N, Ctx_Type);
2796 when N_Null => Resolve_Null (N, Ctx_Type);
2798 when N_Op_And | N_Op_Or | N_Op_Xor
2799 => Resolve_Logical_Op (N, Ctx_Type);
2801 when N_Op_Eq | N_Op_Ne
2802 => Resolve_Equality_Op (N, Ctx_Type);
2804 when N_Op_Lt | N_Op_Le | N_Op_Gt | N_Op_Ge
2805 => Resolve_Comparison_Op (N, Ctx_Type);
2807 when N_Op_Not => Resolve_Op_Not (N, Ctx_Type);
2809 when N_Op_Add | N_Op_Subtract | N_Op_Multiply |
2810 N_Op_Divide | N_Op_Mod | N_Op_Rem
2812 => Resolve_Arithmetic_Op (N, Ctx_Type);
2814 when N_Op_Concat => Resolve_Op_Concat (N, Ctx_Type);
2816 when N_Op_Expon => Resolve_Op_Expon (N, Ctx_Type);
2818 when N_Op_Plus | N_Op_Minus | N_Op_Abs
2819 => Resolve_Unary_Op (N, Ctx_Type);
2821 when N_Op_Shift => Resolve_Shift (N, Ctx_Type);
2823 when N_Procedure_Call_Statement
2824 => Resolve_Call (N, Ctx_Type);
2826 when N_Operator_Symbol
2827 => Resolve_Operator_Symbol (N, Ctx_Type);
2829 when N_Qualified_Expression
2830 => Resolve_Qualified_Expression (N, Ctx_Type);
2832 -- Why is the following null, needs a comment ???
2834 when N_Quantified_Expression
2835 => null;
2837 -- Nothing to do for Raise_Expression, since we took care of
2838 -- setting the Etype earlier, and no other processing is needed.
2840 when N_Raise_Expression
2841 => null;
2843 when N_Raise_xxx_Error
2844 => Set_Etype (N, Ctx_Type);
2846 when N_Range => Resolve_Range (N, Ctx_Type);
2848 when N_Real_Literal
2849 => Resolve_Real_Literal (N, Ctx_Type);
2851 when N_Reference => Resolve_Reference (N, Ctx_Type);
2853 when N_Selected_Component
2854 => Resolve_Selected_Component (N, Ctx_Type);
2856 when N_Slice => Resolve_Slice (N, Ctx_Type);
2858 when N_String_Literal
2859 => Resolve_String_Literal (N, Ctx_Type);
2861 when N_Subprogram_Info
2862 => Resolve_Subprogram_Info (N, Ctx_Type);
2864 when N_Type_Conversion
2865 => Resolve_Type_Conversion (N, Ctx_Type);
2867 when N_Unchecked_Expression =>
2868 Resolve_Unchecked_Expression (N, Ctx_Type);
2870 when N_Unchecked_Type_Conversion =>
2871 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
2872 end case;
2874 -- Ada 2012 (AI05-0149): Apply an (implicit) conversion to an
2875 -- expression of an anonymous access type that occurs in the context
2876 -- of a named general access type, except when the expression is that
2877 -- of a membership test. This ensures proper legality checking in
2878 -- terms of allowed conversions (expressions that would be illegal to
2879 -- convert implicitly are allowed in membership tests).
2881 if Ada_Version >= Ada_2012
2882 and then Ekind (Ctx_Type) = E_General_Access_Type
2883 and then Ekind (Etype (N)) = E_Anonymous_Access_Type
2884 and then Nkind (Parent (N)) not in N_Membership_Test
2885 then
2886 Rewrite (N, Convert_To (Ctx_Type, Relocate_Node (N)));
2887 Analyze_And_Resolve (N, Ctx_Type);
2888 end if;
2890 -- If the subexpression was replaced by a non-subexpression, then
2891 -- all we do is to expand it. The only legitimate case we know of
2892 -- is converting procedure call statement to entry call statements,
2893 -- but there may be others, so we are making this test general.
2895 if Nkind (N) not in N_Subexpr then
2896 Debug_A_Exit ("resolving ", N, " (done)");
2897 Expand (N);
2898 return;
2899 end if;
2901 -- The expression is definitely NOT overloaded at this point, so
2902 -- we reset the Is_Overloaded flag to avoid any confusion when
2903 -- reanalyzing the node.
2905 Set_Is_Overloaded (N, False);
2907 -- Freeze expression type, entity if it is a name, and designated
2908 -- type if it is an allocator (RM 13.14(10,11,13)).
2910 -- Now that the resolution of the type of the node is complete, and
2911 -- we did not detect an error, we can expand this node. We skip the
2912 -- expand call if we are in a default expression, see section
2913 -- "Handling of Default Expressions" in Sem spec.
2915 Debug_A_Exit ("resolving ", N, " (done)");
2917 -- We unconditionally freeze the expression, even if we are in
2918 -- default expression mode (the Freeze_Expression routine tests this
2919 -- flag and only freezes static types if it is set).
2921 -- Ada 2012 (AI05-177): Expression functions do not freeze. Only
2922 -- their use (in an expanded call) freezes.
2924 if Ekind (Proper_Current_Scope) /= E_Function
2925 or else Nkind (Original_Node (Unit_Declaration_Node
2926 (Proper_Current_Scope))) /= N_Expression_Function
2927 then
2928 Freeze_Expression (N);
2929 end if;
2931 -- Now we can do the expansion
2933 Expand (N);
2934 end if;
2935 end Resolve;
2937 -------------
2938 -- Resolve --
2939 -------------
2941 -- Version with check(s) suppressed
2943 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
2944 begin
2945 if Suppress = All_Checks then
2946 declare
2947 Sva : constant Suppress_Array := Scope_Suppress.Suppress;
2948 begin
2949 Scope_Suppress.Suppress := (others => True);
2950 Resolve (N, Typ);
2951 Scope_Suppress.Suppress := Sva;
2952 end;
2954 else
2955 declare
2956 Svg : constant Boolean := Scope_Suppress.Suppress (Suppress);
2957 begin
2958 Scope_Suppress.Suppress (Suppress) := True;
2959 Resolve (N, Typ);
2960 Scope_Suppress.Suppress (Suppress) := Svg;
2961 end;
2962 end if;
2963 end Resolve;
2965 -------------
2966 -- Resolve --
2967 -------------
2969 -- Version with implicit type
2971 procedure Resolve (N : Node_Id) is
2972 begin
2973 Resolve (N, Etype (N));
2974 end Resolve;
2976 ---------------------
2977 -- Resolve_Actuals --
2978 ---------------------
2980 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
2981 Loc : constant Source_Ptr := Sloc (N);
2982 A : Node_Id;
2983 F : Entity_Id;
2984 A_Typ : Entity_Id;
2985 F_Typ : Entity_Id;
2986 Prev : Node_Id := Empty;
2987 Orig_A : Node_Id;
2989 procedure Check_Argument_Order;
2990 -- Performs a check for the case where the actuals are all simple
2991 -- identifiers that correspond to the formal names, but in the wrong
2992 -- order, which is considered suspicious and cause for a warning.
2994 procedure Check_Prefixed_Call;
2995 -- If the original node is an overloaded call in prefix notation,
2997 -- Try_Object_Operation has already verified that there is a valid
2998 -- interpretation, but the form of the actual can only be determined
2999 -- once the primitive operation is identified.
3002 -- If the actual is missing in a call, insert in the actuals list
3003 -- an instance of the default expression. The insertion is always
3004 -- a named association.
3007 -- Check whether T1 and T2, or their full views, are derived from a
3008 -- common type. Used to enforce the restrictions on array conversions
3009 -- of AI95-00246.
3012 -- Predicate to determine whether an actual that is a concatenation
3013 -- will be evaluated statically and does not need a transient scope.
3014 -- This must be determined before the actual is resolved and expanded
3015 -- because if needed the transient scope must be introduced earlier.
3017 --------------------------
3018 -- Check_Argument_Order --
3019 --------------------------
3022 begin
3023 -- Nothing to do if no parameters, or original node is neither a
3024 -- function call nor a procedure call statement (happens in the
3025 -- operator-transformed-to-function call case), or the call does
3026 -- not come from source, or this warning is off.
3028 if not Warn_On_Parameter_Order
3032 then
3036 declare
3039 begin
3040 -- Nothing to do if only one parameter
3046 -- Here if at least two arguments
3048 declare
3054 -- Set True if an out of order case is found
3056 begin
3057 -- Collect identifier names of actuals, fail if any actual is
3058 -- not a simple identifier, and record max length of name.
3064 else
3070 -- If we got this far, all actuals are identifiers and the list
3071 -- of their names is stored in the Actuals array.
3076 -- If we ran out of formals, that's odd, probably an error
3077 -- which will be detected elsewhere, but abandon the search.
3083 -- If name matches and is in order OK
3088 else
3089 -- If no match, see if it is elsewhere in list and if so
3090 -- flag potential wrong order if type is compatible.
3094 and then
3096 then
3102 -- No match
3110 -- If Formals left over, also probably an error, skip warning
3116 -- Here we give the warning if something was out of order
3119 Error_Msg_N
3126 -------------------------
3127 -- Check_Prefixed_Call --
3128 -------------------------
3137 begin
3138 -- Check whether the call is a prefixed call, with or without
3139 -- additional actuals.
3142 or else
3148 then
3151 then
3152 -- Introduce dereference on object in prefix
3154 New_A :=
3162 then
3163 -- Introduce an implicit 'Access in prefix
3166 Error_Msg_NE
3182 --------------------
3183 -- Insert_Default --
3184 --------------------
3190 begin
3191 -- Missing argument in call, nothing to insert
3196 else
3197 -- Note that we do a full New_Copy_Tree, so that any associated
3198 -- Itypes are properly copied. This may not be needed any more,
3199 -- but it does no harm as a safety measure! Defaults of a generic
3200 -- formal may be out of bounds of the corresponding actual (see
3201 -- cc1311b) and an additional check may be required.
3203 Actval :=
3204 New_Copy_Tree
3211 then
3217 then
3220 then
3221 -- If default is a real literal, do not introduce a
3222 -- conversion whose effect may depend on the run-time
3223 -- size of universal real.
3227 else
3238 -- Resolve aggregates with their base type, to avoid scope
3239 -- anomalies: the subtype was first built in the subprogram
3240 -- declaration, and the current call may be nested.
3244 else
3248 else
3251 -- See note above concerning aggregates
3255 then
3258 -- Resolve entities with their own type, which may differ from
3259 -- the type of a reference in a generic context (the view
3260 -- swapping mechanism did not anticipate the re-analysis of
3261 -- default values in calls).
3266 else
3271 -- If default is a tag indeterminate function call, propagate tag
3272 -- to obtain proper dispatching.
3276 then
3282 -- If the default expression raises constraint error, then just
3283 -- silently replace it with an N_Raise_Constraint_Error node, since
3284 -- we already gave the warning on the subprogram spec. If node is
3285 -- already a Raise_Constraint_Error leave as is, to prevent loops in
3286 -- the warnings removal machinery.
3290 then
3298 Assoc :=
3303 -- Case of insertion is first named actual
3307 then
3314 else
3318 else
3322 -- Case of insertion is not first named actual
3324 else
3325 Set_Next_Named_Actual
3337 -------------------
3338 -- Same_Ancestor --
3339 -------------------
3345 begin
3348 then
3354 then
3361 --------------------------
3362 -- Static_Concatenation --
3363 --------------------------
3366 begin
3373 -- Concatenation is static when both operands are static and
3374 -- the concatenation operator is a predefined one.
3377 and then
3379 and then
3384 declare
3386 begin
3389 and then
3393 else
3399 -- Start of processing for Resolve_Actuals
3401 begin
3402 Check_Argument_Order;
3406 Check_Prefixed_Call;
3415 -- If we have an error in any actual or formal, indicated by a type
3416 -- of Any_Type, then abandon resolution attempt, and set result type
3417 -- to Any_Type.
3421 then
3426 -- Case where actual is present
3428 -- If the actual is an entity, generate a reference to it now. We
3429 -- do this before the actual is resolved, because a formal of some
3430 -- protected subprogram, or a task discriminant, will be rewritten
3431 -- during expansion, and the source entity reference may be lost.
3436 then
3442 then
3449 -- RM 6.4.1(12): For an out parameter that is passed by
3450 -- copy, the formal parameter object is created, and:
3452 -- * For an access type, the formal parameter is initialized
3453 -- from the value of the actual, without checking that the
3454 -- value satisfies any constraint, any predicate, or any
3455 -- exclusion of the null value.
3457 -- * For a scalar type that has the Default_Value aspect
3458 -- specified, the formal parameter is initialized from the
3459 -- value of the actual, without checking that the value
3460 -- satisfies any constraint or any predicate.
3461 -- I do not understand why this case is included??? this is
3462 -- not a case where an OUT parameter is treated as IN OUT.
3464 -- * For a composite type with discriminants or that has
3465 -- implicit initial values for any subcomponents, the
3466 -- behavior is as for an in out parameter passed by copy.
3468 -- Hence for these cases we generate the read reference now
3469 -- (the write reference will be generated later by
3470 -- Note_Possible_Modification).
3473 and then
3475 or else
3477 and then
3479 or else
3482 or else Is_Partially_Initialized_Type
3484 then
3494 then
3495 -- If style checking mode on, check match of formal name
3503 -- If the formal is Out or In_Out, do not resolve and expand the
3504 -- conversion, because it is subsequently expanded into explicit
3505 -- temporaries and assignments. However, the object of the
3506 -- conversion can be resolved. An exception is the case of tagged
3507 -- type conversion with a class-wide actual. In that case we want
3508 -- the tag check to occur and no temporary will be needed (no
3509 -- representation change can occur) and the parameter is passed by
3510 -- reference, so we go ahead and resolve the type conversion.
3511 -- Another exception is the case of reference to component or
3512 -- subcomponent of a bit-packed array, in which case we want to
3513 -- defer expansion to the point the in and out assignments are
3514 -- performed.
3519 then
3522 then
3523 -- In a view conversion, the conversion must be legal in
3524 -- both directions, and thus both component types must be
3525 -- aliased, or neither (4.6 (8)).
3527 -- The extra rule in 4.6 (24.9.2) seems unduly restrictive:
3528 -- the privacy requirement should not apply to generic
3529 -- types, and should be checked in an instance. ARG query
3530 -- is in order ???
3534 then
3535 Error_Msg_N
3539 -- Comment here??? what set of cases???
3541 elsif
3543 then
3544 -- Check view conv between unrelated by ref array types
3548 then
3549 Error_Msg_N
3553 -- In Ada 2005 mode, check view conversion component
3554 -- type cannot be private, tagged, or volatile. Note
3555 -- that we only apply this to source conversions. The
3556 -- generated code can contain conversions which are
3557 -- not subject to this test, and we cannot extract the
3558 -- component type in such cases since it is not present.
3562 then
3563 declare
3565 Component_Type
3567 begin
3572 then
3573 Error_Msg_N
3584 -- Resolve expression if conversion is all OK
3589 then
3593 -- If the actual is a function call that returns a limited
3594 -- unconstrained object that needs finalization, create a
3595 -- transient scope for it, so that it can receive the proper
3596 -- finalization list.
3601 and then Full_Expander_Active
3603 then
3607 -- A small optimization: if one of the actuals is a concatenation
3608 -- create a block around a procedure call to recover stack space.
3609 -- This alleviates stack usage when several procedure calls in
3610 -- the same statement list use concatenation. We do not perform
3611 -- this wrapping for code statements, where the argument is a
3612 -- static string, and we want to preserve warnings involving
3613 -- sequences of such statements.
3617 and then Full_Expander_Active
3618 and then
3622 then
3626 else
3630 and then
3633 then
3634 Error_Msg_N
3647 -- (Ada 2005: AI-251): If the actual is an allocator whose
3648 -- directly designated type is a class-wide interface, we build
3649 -- an anonymous access type to use it as the type of the
3650 -- allocator. Later, when the subprogram call is expanded, if
3651 -- the interface has a secondary dispatch table the expander
3652 -- will add a type conversion to force the correct displacement
3653 -- of the pointer.
3656 declare
3662 begin
3665 then
3673 -- Ada 2005, AI-162:If the actual is an allocator, the
3674 -- innermost enclosing statement is the master of the
3675 -- created object. This needs to be done with expansion
3676 -- enabled only, otherwise the transient scope will not
3677 -- be removed in the expansion of the wrapped construct.
3680 and then Full_Expander_Active
3681 then
3691 -- (Ada 2005): The call may be to a primitive operation of a
3692 -- tagged synchronized type, declared outside of the type. In
3693 -- this case the controlling actual must be converted to its
3694 -- corresponding record type, which is the formal type. The
3695 -- actual may be a subtype, either because of a constraint or
3696 -- because it is a generic actual, so use base type to locate
3697 -- concurrent type.
3704 then
3705 -- If the actual is overloaded, look for an interpretation
3706 -- that has a synchronized type.
3711 else
3712 declare
3716 begin
3721 then
3731 declare
3734 begin
3737 else
3741 -- Tagged synchronized type (case 1): the actual is a
3742 -- concurrent type.
3746 then
3748 Unchecked_Convert_To
3752 -- Tagged synchronized type (case 2): the formal is a
3753 -- concurrent type.
3756 and then Present
3761 then
3764 -- Common case
3766 else
3770 else
3772 -- not a synchronized operation.
3783 N_Procedure_Call_Statement)
3784 then
3785 -- In formal mode, check that actual parameters matching
3786 -- formals of tagged types are objects (or ancestor type
3787 -- conversions of objects), not general expressions.
3794 declare
3799 begin
3801 Check_SPARK_Restriction
3804 -- In formal mode, the only view conversions are those
3805 -- involving ancestor conversion of an extended type.
3807 elsif not
3813 then
3814 if Ekind_In
3816 then
3817 Check_SPARK_Restriction
3820 else
3821 Check_SPARK_Restriction
3825 else
3830 else
3834 -- In formal mode, the only view conversions are those
3835 -- involving ancestor conversion of an extended type.
3839 then
3840 Check_SPARK_Restriction
3846 -- has warnings suppressed, then we reset Never_Set_In_Source for
3847 -- the calling entity. The reason for this is to catch cases like
3848 -- GNAT.Spitbol.Patterns.Vstring_Var where the called subprogram
3849 -- uses trickery to modify an IN parameter.
3856 then
3860 -- Perform error checks for IN and IN OUT parameters
3864 -- Check unset reference. For scalar parameters, it is clearly
3865 -- wrong to pass an uninitialized value as either an IN or
3866 -- IN-OUT parameter. For composites, it is also clearly an
3867 -- error to pass a completely uninitialized value as an IN
3868 -- parameter, but the case of IN OUT is trickier. We prefer
3869 -- not to give a warning here. For example, suppose there is
3870 -- a routine that sets some component of a record to False.
3871 -- It is perfectly reasonable to make this IN-OUT and allow
3872 -- either initialized or uninitialized records to be passed
3873 -- in this case.
3875 -- For partially initialized composite values, we also avoid
3876 -- warnings, since it is quite likely that we are passing a
3877 -- partially initialized value and only the initialized fields
3878 -- will in fact be read in the subprogram.
3883 then
3887 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
3888 -- actual to a nested call, since this is case of reading an
3889 -- out parameter, which is not allowed.
3894 then
3899 -- Case of OUT or IN OUT parameter
3903 -- For an Out parameter, check for useless assignment. Note
3904 -- that we can't set Last_Assignment this early, because we may
3905 -- kill current values in Resolve_Call, and that call would
3906 -- clobber the Last_Assignment field.
3908 -- Note: call Warn_On_Useless_Assignment before doing the check
3909 -- below for Is_OK_Variable_For_Out_Formal so that the setting
3910 -- of Referenced_As_LHS/Referenced_As_Out_Formal properly
3911 -- reflects the last assignment, not this one!
3918 then
3923 -- Validate the form of the actual. Note that the call to
3924 -- Is_OK_Variable_For_Out_Formal generates the required
3925 -- reference in this case.
3927 -- A call to an initialization procedure for an aggregate
3928 -- component may initialize a nested component of a constant
3929 -- designated object. In this context the object is variable.
3933 then
3937 -- What's the following about???
3941 else
3942 Kill_All_Checks;
3951 -- Apply appropriate range checks for in, out, and in-out
3952 -- parameters. Out and in-out parameters also need a separate
3953 -- check, if there is a type conversion, to make sure the return
3954 -- value meets the constraints of the variable before the
3955 -- conversion.
3957 -- Gigi looks at the check flag and uses the appropriate types.
3958 -- For now since one flag is used there is an optimization which
3959 -- might not be done in the In Out case since Gigi does not do
3960 -- any analysis. More thought required about this ???
3964 -- Apply predicate checks, unless this is a call to the
3965 -- predicate check function itself, which would cause an
3966 -- infinite recursion, or it is a call to an initialization
3967 -- procedure whose operand is of course an unfinished object.
3971 or else
3974 then
3978 -- Apply required constraint checks
3991 then
3997 then
4003 then
4006 else
4010 -- Ada 2005 (AI-231): Note that the controlling parameter case
4011 -- already existed in Ada 95, which is partially checked
4012 -- elsewhere (see Checks), and we don't want the warning
4013 -- message to differ.
4018 then
4020 Apply_Compile_Time_Constraint_Error
4026 Apply_Compile_Time_Constraint_Error
4038 Apply_Scalar_Range_Check
4040 else
4041 Apply_Range_Check
4045 else
4050 then
4052 else
4058 -- An actual associated with an access parameter is implicitly
4059 -- converted to the anonymous access type of the formal and must
4060 -- satisfy the legality checks for access conversions.
4064 Error_Msg_N
4068 -- If the actual is an access selected component of a variable,
4069 -- the call may modify its designated object. It is reasonable
4070 -- to treat this as a potential modification of the enclosing
4071 -- record, to prevent spurious warnings that it should be
4072 -- declared as a constant, because intuitively programmers
4073 -- regard the designated subcomponent as part of the record.
4078 then
4083 -- Check bad case of atomic/volatile argument (RM C.6(12))
4087 then
4090 then
4091 Error_Msg_NE
4097 then
4098 Error_Msg_NE
4104 -- Check that subprograms don't have improper controlling
4105 -- arguments (RM 3.9.2 (9)).
4107 -- A primitive operation may have an access parameter of an
4108 -- incomplete tagged type, but a dispatching call is illegal
4109 -- if the type is still incomplete.
4115 declare
4117 begin
4121 then
4122 Error_Msg_NE
4136 then
4141 then
4143 Error_Msg_NE
4147 -- Apply the checks described in 3.10.2(27): if the context is a
4148 -- specific access-to-object, the actual cannot be class-wide.
4149 -- Use base type to exclude access_to_subprogram cases.
4156 and then
4161 -- Disable these checks for call to imported C++ subprograms
4163 and then not
4167 then
4168 Error_Msg_N
4173 Error_Msg_NE
4180 -- If it is a named association, treat the selector_name as a
4181 -- proper identifier, and mark the corresponding entity. Ignore
4182 -- this reference in SPARK mode, as it refers to an entity not in
4183 -- scope at the point of reference, so the reference should be
4184 -- ignored for computing effects of subprograms.
4187 and then not SPARK_Mode
4188 then
4203 -- Case where actual is not present
4205 else
4206 Insert_Default;
4213 -----------------------
4214 -- Resolve_Allocator --
4215 -----------------------
4227 procedure Check_Allocator_Discrim_Accessibility
4230 -- Check that accessibility level associated with an access discriminant
4231 -- initialized in an allocator by the expression Disc_Exp is not deeper
4232 -- than the level of the allocator type Alloc_Typ. An error message is
4233 -- issued if this condition is violated. Specialized checks are done for
4234 -- the cases of a constraint expression which is an access attribute or
4235 -- an access discriminant.
4238 -- If the allocator is an actual in a call, it is allowed to be class-
4239 -- wide when the context is not because it is a controlling actual.
4241 -------------------------------------------
4242 -- Check_Allocator_Discrim_Accessibility --
4243 -------------------------------------------
4245 procedure Check_Allocator_Discrim_Accessibility
4248 is
4249 begin
4252 then
4253 Error_Msg_N
4256 -- When the expression is an Access attribute the level of the prefix
4257 -- object must not be deeper than that of the allocator's type.
4261 Attribute_Access
4264 then
4265 Error_Msg_N
4267 Disc_Exp);
4269 -- When the expression is an access discriminant the check is against
4270 -- the level of the prefix object.
4276 then
4277 Error_Msg_N
4279 Disc_Exp);
4281 -- All other cases are legal
4283 else
4288 ----------------------------
4289 -- In_Dispatching_Context --
4290 ----------------------------
4295 begin
4301 -- Start of processing for Resolve_Allocator
4303 begin
4304 -- Replace general access with specific type
4314 -- For qualified expression, resolve the expression using the given
4315 -- subtype (nothing to do for type mark, subtype indication)
4320 and then not In_Dispatching_Context
4321 then
4322 Error_Msg_N
4329 -- A qualified expression requires an exact match of the type.
4330 -- Class-wide matching is not allowed.
4335 then
4339 -- Calls to build-in-place functions are not currently supported in
4340 -- allocators for access types associated with a simple storage pool.
4341 -- Supporting such allocators may require passing additional implicit
4342 -- parameters to build-in-place functions (or a significant revision
4343 -- of the current b-i-p implementation to unify the handling for
4344 -- multiple kinds of storage pools). ???
4348 then
4349 declare
4352 begin
4354 and then
4355 Present (Get_Rep_Pragma
4357 then
4358 Error_Msg_N
4365 -- A special accessibility check is needed for allocators that
4366 -- constrain access discriminants. The level of the type of the
4367 -- expression used to constrain an access discriminant cannot be
4368 -- deeper than the type of the allocator (in contrast to access
4369 -- parameters, where the level of the actual can be arbitrary).
4371 -- We can't use Valid_Conversion to perform this check because in
4372 -- general the type of the allocator is unrelated to the type of
4373 -- the access discriminant.
4377 then
4384 then
4387 -- Get the first component expression of the aggregate
4397 else
4401 else
4420 else
4425 else
4434 -- For a subtype mark or subtype indication, freeze the subtype
4436 else
4440 Error_Msg_N
4444 -- A special accessibility check is needed for allocators that
4445 -- constrain access discriminants. The level of the type of the
4446 -- expression used to constrain an access discriminant cannot be
4447 -- deeper than the type of the allocator (in contrast to access
4448 -- parameters, where the level of the actual can be arbitrary).
4449 -- We can't use Valid_Conversion to perform this check because
4450 -- in general the type of the allocator is unrelated to the type
4451 -- of the access discriminant.
4456 then
4466 else
4480 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
4481 -- check that the level of the type of the created object is not deeper
4482 -- than the level of the allocator's access type, since extensions can
4483 -- now occur at deeper levels than their ancestor types. This is a
4484 -- static accessibility level check; a run-time check is also needed in
4485 -- the case of an initialized allocator with a class-wide argument (see
4486 -- Expand_Allocator_Expression).
4490 then
4491 declare
4494 begin
4499 else
4505 then
4507 Error_Msg_N
4510 Error_Msg_N
4517 -- Do not apply Ada 2005 accessibility checks on a class-wide
4518 -- allocator if the type given in the allocator is a formal
4519 -- type. A run-time check will be performed in the instance.
4529 -- Check for allocation from an empty storage pool
4534 -- If the context is an unchecked conversion, as may happen within an
4535 -- inlined subprogram, the allocator is being resolved with its own
4536 -- anonymous type. In that case, if the target type has a specific
4537 -- storage pool, it must be inherited explicitly by the allocator type.
4541 then
4542 Set_Associated_Storage_Pool
4550 -- Check that an allocator with task parts isn't for a nested access
4551 -- type when restriction No_Task_Hierarchy applies.
4555 then
4559 -- An erroneous allocator may be rewritten as a raise Program_Error
4560 -- statement.
4564 -- An anonymous access discriminant is the definition of a
4565 -- coextension.
4569 N_Discriminant_Specification
4570 then
4571 declare
4575 begin
4578 -- Ada 2012 AI05-0052: If the designated type of the allocator
4579 -- is limited, then the allocator shall not be used to define
4580 -- the value of an access discriminant unless the discriminated
4581 -- type is immutably limited.
4586 then
4587 Error_Msg_N
4593 -- Avoid marking an allocator as a dynamic coextension if it is
4594 -- within a static construct.
4600 -- Cleanup for potential static coextensions
4602 else
4608 -- Report a simple error: if the designated object is a local task,
4609 -- its body has not been seen yet, and its activation will fail an
4610 -- elaboration check.
4617 then
4622 -- Ada 2012 (AI05-0111-3): Detect an attempt to allocate a task or a
4623 -- type with a task component on a subpool. This action must raise
4624 -- Program_Error at runtime.
4630 then
4641 ---------------------------
4642 -- Resolve_Arithmetic_Op --
4643 ---------------------------
4645 -- Used for resolving all arithmetic operators except exponentiation
4656 -- We do the resolution using the base type, because intermediate values
4657 -- in expressions always are of the base type, not a subtype of it.
4660 -- Returns True if N is in a context that expects "any real type"
4663 -- Return True iff given type is Integer or universal real/integer
4666 -- Choose type of integer literal in fixed-point operation to conform
4667 -- to available fixed-point type. T is the type of the other operand,
4668 -- which is needed to determine the expected type of N.
4671 -- Set operand type to T if universal
4673 -------------------------------
4674 -- Expected_Type_Is_Any_Real --
4675 -------------------------------
4678 begin
4679 -- N is the expression after "delta" in a fixed_point_definition;
4680 -- see RM-3.5.9(6):
4683 N_Decimal_Fixed_Point_Definition,
4685 -- N is one of the bounds in a real_range_specification;
4686 -- see RM-3.5.7(5):
4688 N_Real_Range_Specification,
4690 -- N is the expression of a delta_constraint;
4691 -- see RM-J.3(3):
4693 N_Delta_Constraint);
4696 -----------------------------
4697 -- Is_Integer_Or_Universal --
4698 -----------------------------
4705 begin
4711 else
4717 then
4728 ----------------------------
4729 -- Set_Mixed_Mode_Operand --
4730 ----------------------------
4736 begin
4739 -- A universal integer literal is resolved as standard integer
4740 -- except in the case of a fixed-point result, where we leave it
4741 -- as universal (to be handled by Exp_Fixd later on)
4745 else
4753 then
4754 -- A universal real can appear in a fixed-type context. We resolve
4755 -- the literal with that context, even though this might raise an
4756 -- exception prematurely (the other operand may be zero).
4763 then
4764 -- Integer arg in mixed-mode operation. Resolve with universal
4765 -- type, in case preference rule must be applied.
4771 then
4772 -- Not a mixed-mode operation, resolve with context
4778 -- N may itself be a mixed-mode operation, so use context type
4785 then
4786 -- Must be (fixed * fixed) operation, operand must have one
4787 -- compatible interpretation.
4794 then
4795 -- C * F(X) in a fixed context, where C is a real literal or a
4796 -- fixed-point expression. F must have either a fixed type
4797 -- interpretation or an integer interpretation, but not both.
4804 else
4811 else
4819 -- Reanalyze the literal with the fixed type of the context. If
4820 -- context is Universal_Fixed, we are within a conversion, leave
4821 -- the literal as a universal real because there is no usable
4822 -- fixed type, and the target of the conversion plays no role in
4823 -- the resolution.
4825 declare
4829 begin
4832 else
4838 then
4840 else
4848 else
4853 ----------------------
4854 -- Set_Operand_Type --
4855 ----------------------
4858 begin
4861 then
4866 -- Start of processing for Resolve_Arithmetic_Op
4868 begin
4873 then
4877 -- Special-case for mixed-mode universal expressions or fixed point type
4878 -- operation: each argument is resolved separately. The same treatment
4879 -- is required if one of the operands of a fixed point operation is
4880 -- universal real, since in this case we don't do a conversion to a
4881 -- specific fixed-point type (instead the expander handles the case).
4883 -- Set the type of the node to its universal interpretation because
4884 -- legality checks on an exponentiation operand need the context.
4889 then
4900 or else
4903 then
4908 -- If context is a fixed type and one operand is integer, the other
4909 -- is resolved with the type of the context.
4914 then
4921 then
4925 else
4930 -- Check the rule in RM05-4.5.5(19.1/2) disallowing universal_fixed
4931 -- multiplying operators from being used when the expected type is
4932 -- also universal_fixed. Note that B_Typ will be Universal_Fixed in
4933 -- some cases where the expected type is actually Any_Real;
4934 -- Expected_Type_Is_Any_Real takes care of that case.
4938 then
4942 N_Unchecked_Type_Conversion)
4943 then
4950 else
4953 and then not
4955 N_Unchecked_Type_Conversion)
4956 then
4957 Error_Msg_N
4962 -- The expected type is "any real type" in contexts like
4964 -- type T is delta <universal_fixed-expression> ...
4966 -- in which case we need to set the type to Universal_Real
4967 -- so that static expression evaluation will work properly.
4971 else
4981 then
4986 -- If no previous errors, this is only possible if one operand is
4987 -- overloaded and the context is universal. Resolve as such.
4992 else
4994 and then
4996 then
5000 -- If the context is Universal_Fixed and the operands are also
5001 -- universal fixed, this is an error, unless there is only one
5002 -- applicable fixed_point type (usually Duration).
5010 else
5015 else
5020 -- If one of the arguments was resolved to a non-universal type.
5021 -- label the result of the operation itself with the same type.
5022 -- Do the same for the universal argument, if any.
5034 -- In SPARK, a multiplication or division with operands of fixed point
5035 -- types shall be qualified or explicitly converted to identify the
5036 -- result type.
5041 and then
5043 then
5044 Check_SPARK_Restriction
5048 -- Set overflow and division checking bit
5055 -- Give warning if explicit division by zero
5059 then
5065 or else
5068 then
5069 -- Specialize the warning message according to the operation.
5070 -- The following warnings are for the case
5075 -- For division, we have two cases, for float division
5076 -- of an unconstrained float type, on a machine where
5077 -- Machine_Overflows is false, we don't get an exception
5078 -- at run-time, but rather an infinity or Nan. The Nan
5079 -- case is pretty obscure, so just warn about infinities.
5083 and then not Machine_Overflows_On_Target
5084 then
5085 Error_Msg_N
5089 -- For all other cases, we get a Constraint_Error
5091 else
5092 Apply_Compile_Time_Constraint_Error
5098 Apply_Compile_Time_Constraint_Error
5103 Apply_Compile_Time_Constraint_Error
5107 -- Division by zero can only happen with division, rem,
5108 -- and mod operations.
5114 -- Otherwise just set the flag to check at run time
5116 else
5121 -- If Restriction No_Implicit_Conditionals is active, then it is
5122 -- violated if either operand can be negative for mod, or for rem
5123 -- if both operands can be negative.
5127 then
5128 declare
5135 -- Set if corresponding operand might be negative
5137 begin
5138 Determine_Range
5142 Determine_Range
5146 -- Check if we will be generating conditionals. There are two
5147 -- cases where that can happen, first for REM, the only case
5148 -- is largest negative integer mod -1, where the division can
5149 -- overflow, but we still have to give the right result. The
5150 -- front end generates a test for this annoying case. Here we
5151 -- just test if both operands can be negative (that's what the
5152 -- expander does, so we match its logic here).
5154 -- The second case is mod where either operand can be negative.
5155 -- In this case, the back end has to generate additional tests.
5158 or else
5160 then
5172 ------------------
5173 -- Resolve_Call --
5174 ------------------
5186 function Same_Or_Aliased_Subprograms
5189 -- Returns True if the subprogram entity S is the same as E or else
5190 -- S is an alias of E.
5192 ---------------------------------
5193 -- Same_Or_Aliased_Subprograms --
5194 ---------------------------------
5196 function Same_Or_Aliased_Subprograms
5199 is
5201 begin
5206 -- Start of processing for Resolve_Call
5208 begin
5209 -- The context imposes a unique interpretation with type Typ on a
5210 -- procedure or function call. Find the entity of the subprogram that
5211 -- yields the expected type, and propagate the corresponding formal
5212 -- constraints on the actuals. The caller has established that an
5213 -- interpretation exists, and emitted an error if not unique.
5215 -- First deal with the case of a call to an access-to-subprogram,
5216 -- dereference made explicit in Analyze_Call.
5222 else
5223 -- Find the interpretation whose type (a subprogram type) has a
5224 -- return type that is compatible with the context. Analysis of
5225 -- the node has established that one exists.
5244 -- If the prefix is not an entity, then resolve it
5250 -- For an indirect call, we always invalidate checks, since we do not
5251 -- know whether the subprogram is local or global. Yes we could do
5252 -- better here, e.g. by knowing that there are no local subprograms,
5253 -- but it does not seem worth the effort. Similarly, we kill all
5254 -- knowledge of current constant values.
5256 Kill_Current_Values;
5258 -- If this is a procedure call which is really an entry call, do
5259 -- the conversion of the procedure call to an entry call. Protected
5260 -- operations use the same circuitry because the name in the call
5261 -- can be an arbitrary expression with special resolution rules.
5266 then
5270 -- Kill checks and constant values, as above for indirect case
5271 -- Who knows what happens when another task is activated?
5273 Kill_Current_Values;
5276 -- Normal subprogram call with name established in Resolve
5282 -- Otherwise we must have the case of an overloaded call
5284 else
5287 -- Initialize Nam to prevent warning (we know it will be assigned
5288 -- in the loop below, but the compiler does not know that).
5308 then
5309 -- The prefix is a parameterless function call that returns an access
5310 -- to subprogram. If parameters are present in the current call, add
5311 -- add an explicit dereference. We use the base type here because
5312 -- within an instance these may be subtypes.
5314 -- The dereference is added either in Analyze_Call or here. Should
5315 -- be consolidated ???
5324 -- Check that a call to Current_Task does not occur in an entry body
5327 declare
5330 begin
5332 loop
5335 -- Exclude calls that occur within the default of a formal
5336 -- parameter of the entry, since those are evaluated outside
5337 -- of the body.
5344 then
5346 Error_Msg_NE
5349 Error_Msg_NE
5361 -- Check that a procedure call does not occur in the context of the
5362 -- entry call statement of a conditional or timed entry call. Note that
5363 -- the case of a call to a subprogram renaming of an entry will also be
5364 -- rejected. The test for N not being an N_Entry_Call_Statement is
5365 -- defensive, covering the possibility that the processing of entry
5366 -- calls might reach this point due to later modifications of the code
5367 -- above.
5372 then
5376 -- Ada 2005 (AI-345): If a procedure_call_statement is used
5377 -- for a procedure_or_entry_call, the procedure_name or
5378 -- procedure_prefix of the procedure_call_statement shall denote
5379 -- an entry renamed by a procedure, or (a view of) a primitive
5380 -- subprogram of a limited interface whose first parameter is
5381 -- a controlling parameter.
5386 then
5387 Error_Msg_N
5392 -- Check that this is not a call to a protected procedure or entry from
5393 -- within a protected function.
5397 -- Freeze the subprogram name if not in a spec-expression. Note that
5398 -- we freeze procedure calls as well as function calls. Procedure calls
5399 -- are not frozen according to the rules (RM 13.14(14)) because it is
5400 -- impossible to have a procedure call to a non-frozen procedure in
5401 -- pure Ada, but in the code that we generate in the expander, this
5402 -- rule needs extending because we can generate procedure calls that
5403 -- need freezing.
5405 -- In Ada 2012, expression functions may be called within pre/post
5406 -- conditions of subsequent functions or expression functions. Such
5407 -- calls do not freeze when they appear within generated bodies,
5408 -- (including the body of another expression function) which would
5409 -- place the freeze node in the wrong scope. An expression function
5410 -- is frozen in the usual fashion, by the appearance of a real body,
5411 -- or at the end of a declarative part.
5415 and then
5418 then
5422 -- For a predefined operator, the type of the result is the type imposed
5423 -- by context, except for a predefined operation on universal fixed.
5424 -- Otherwise The type of the call is the type returned by the subprogram
5425 -- being called.
5432 -- If the subprogram returns an array type, and the context requires the
5433 -- component type of that array type, the node is really an indexing of
5434 -- the parameterless call. Resolve as such. A pathological case occurs
5435 -- when the type of the component is an access to the array type. In
5436 -- this case the call is truly ambiguous.
5439 and then
5444 and then
5445 Covers
5448 then
5449 declare
5454 begin
5457 then
5458 Error_Msg_N
5460 else
5466 or else
5468 and then
5470 then
5473 -- Indexed call to a parameterless function
5475 Index_Node :=
5477 Prefix =>
5481 else
5482 -- An Ada 2005 prefixed call to a primitive operation
5483 -- whose first parameter is the prefix. This prefix was
5484 -- prepended to the parameter list, which is actually a
5485 -- list of indexes. Remove the prefix in order to build
5486 -- the proper indexed component.
5488 Index_Node :=
5490 Prefix =>
5493 Parameter_Associations =>
5494 New_List
5499 -- Preserve the parenthesis count of the node
5503 -- Since we are correcting a node classification error made
5504 -- by the parser, we call Replace rather than Rewrite.
5518 else
5522 -- In the case where the call is to an overloaded subprogram, Analyze
5523 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
5524 -- such a case Normalize_Actuals needs to be called once more to order
5525 -- the actuals correctly. Otherwise the call will have the ordering
5526 -- given by the last overloaded subprogram whether this is the correct
5527 -- one being called or not.
5534 -- In any case, call is fully resolved now. Reset Overload flag, to
5535 -- prevent subsequent overload resolution if node is analyzed again
5540 -- If we are calling the current subprogram from immediately within its
5541 -- body, then that is the case where we can sometimes detect cases of
5542 -- infinite recursion statically. Do not try this in case restriction
5543 -- No_Recursion is in effect anyway, and do it only for source calls.
5548 -- Issue warning for possible infinite recursion in the absence
5549 -- of the No_Recursion restriction.
5554 then
5555 -- Here we detected and flagged an infinite recursion, so we do
5556 -- not need to test the case below for further warnings. Also we
5557 -- are all done if we now have a raise SE node.
5563 -- If call is to immediately containing subprogram, then check for
5564 -- the case of a possible run-time detectable infinite recursion.
5566 else
5570 -- Although in general case, recursion is not statically
5571 -- checkable, the case of calling an immediately containing
5572 -- subprogram is easy to catch.
5576 -- If the recursive call is to a parameterless subprogram,
5577 -- then even if we can't statically detect infinite
5578 -- recursion, this is pretty suspicious, and we output a
5579 -- warning. Furthermore, we will try later to detect some
5580 -- cases here at run time by expanding checking code (see
5581 -- Detect_Infinite_Recursion in package Exp_Ch6).
5583 -- If the recursive call is within a handler, do not emit a
5584 -- warning, because this is a common idiom: loop until input
5585 -- is correct, catch illegal input in handler and restart.
5591 then
5592 -- For the case of a procedure call. We give the message
5593 -- only if the call is the first statement in a sequence
5594 -- of statements, or if all previous statements are
5595 -- simple assignments. This is simply a heuristic to
5596 -- decrease false positives, without losing too many good
5597 -- warnings. The idea is that these previous statements
5598 -- may affect global variables the procedure depends on.
5599 -- We also exclude raise statements, that may arise from
5600 -- constraint checks and are probably unrelated to the
5601 -- intended control flow.
5605 then
5606 declare
5608 begin
5612 N_Assignment_Statement,
5613 N_Raise_Constraint_Error)
5614 then
5623 -- Do not give warning if we are in a conditional context
5625 declare
5627 begin
5633 then
5638 -- Here warning is to be issued
5641 Error_Msg_N
5643 Error_Msg_N
5655 -- Check obsolescent reference to Ada.Characters.Handling subprogram
5659 -- If subprogram name is a predefined operator, it was given in
5660 -- functional notation. Replace call node with operator node, so
5661 -- that actuals can be resolved appropriately.
5669 then
5675 -- Create a transient scope if the resulting type requires it
5677 -- There are several notable exceptions:
5679 -- a) In init procs, the transient scope overhead is not needed, and is
5680 -- even incorrect when the call is a nested initialization call for a
5681 -- component whose expansion may generate adjust calls. However, if the
5682 -- call is some other procedure call within an initialization procedure
5683 -- (for example a call to Create_Task in the init_proc of the task
5684 -- run-time record) a transient scope must be created around this call.
5686 -- b) Enumeration literal pseudo-calls need no transient scope
5688 -- c) Intrinsic subprograms (Unchecked_Conversion and source info
5689 -- functions) do not use the secondary stack even though the return
5690 -- type may be unconstrained.
5692 -- d) Calls to a build-in-place function, since such functions may
5693 -- allocate their result directly in a target object, and cases where
5694 -- the result does get allocated in the secondary stack are checked for
5695 -- within the specialized Exp_Ch6 procedures for expanding those
5696 -- build-in-place calls.
5698 -- e) If the subprogram is marked Inline_Always, then even if it returns
5699 -- an unconstrained type the call does not require use of the secondary
5700 -- stack. However, inlining will only take place if the body to inline
5701 -- is already present. It may not be available if e.g. the subprogram is
5702 -- declared in a child instance.
5704 -- If this is an initialization call for a type whose construction
5705 -- uses the secondary stack, and it is not a nested call to initialize
5706 -- a component, we do need to create a transient scope for it. We
5707 -- check for this by traversing the type in Check_Initialization_Call.
5713 and then not Debug_Flag_Dot_K
5714 then
5721 and then Debug_Flag_Dot_K
5722 then
5728 then
5731 elsif Full_Expander_Active
5734 and then
5736 or else
5738 then
5741 -- If the call appears within the bounds of a loop, it will
5742 -- be rewritten and reanalyzed, nothing left to do here.
5749 and then not Within_Init_Proc
5750 then
5754 -- A protected function cannot be called within the definition of the
5755 -- enclosing protected type.
5760 then
5761 Error_Msg_NE
5765 -- Propagate interpretation to actuals, and add default expressions
5766 -- where needed.
5771 -- Overloaded literals are rewritten as function calls, for purpose of
5772 -- resolution. After resolution, we can replace the call with the
5773 -- literal itself.
5779 -- Avoid validation, since it is a static function call
5785 -- If the subprogram is not global, then kill all saved values and
5786 -- checks. This is a bit conservative, since in many cases we could do
5787 -- better, but it is not worth the effort. Similarly, we kill constant
5788 -- values. However we do not need to do this for internal entities
5789 -- (unless they are inherited user-defined subprograms), since they
5790 -- are not in the business of molesting local values.
5792 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
5793 -- kill all checks and values for calls to global subprograms. This
5794 -- takes care of the case where an access to a local subprogram is
5795 -- taken, and could be passed directly or indirectly and then called
5796 -- from almost any context.
5798 -- Note: we do not do this step till after resolving the actuals. That
5799 -- way we still take advantage of the current value information while
5800 -- scanning the actuals.
5802 -- We suppress killing values if we are processing the nodes associated
5803 -- with N_Freeze_Entity nodes. Otherwise the declaration of a tagged
5804 -- type kills all the values as part of analyzing the code that
5805 -- initializes the dispatch tables.
5809 or else Suppress_Value_Tracking_On_Call
5814 then
5815 Kill_Current_Values;
5818 -- If we are warning about unread OUT parameters, this is the place to
5819 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
5820 -- after the above call to Kill_Current_Values (since that call clears
5821 -- the Last_Assignment field of all local variables).
5826 then
5827 declare
5831 begin
5841 then
5851 -- If the subprogram is a primitive operation, check whether or not
5852 -- it is a correct dispatching call.
5856 then
5861 and then not In_Instance
5862 then
5866 -- If this is a dispatching call, generate the appropriate reference,
5867 -- for better source navigation in GPS.
5871 then
5874 -- Normal case, not a dispatching call: generate a call reference
5876 else
5884 -- Check for violation of restriction No_Specific_Termination_Handlers
5885 -- and warn on a potentially blocking call to Abort_Task.
5889 or else
5891 then
5898 -- A call to Ada.Real_Time.Timing_Events.Set_Handler to set a relative
5899 -- timing event violates restriction No_Relative_Delay (AI-0211). We
5900 -- need to check the second argument to determine whether it is an
5901 -- absolute or relative timing event.
5906 then
5910 -- Issue an error for a call to an eliminated subprogram. This routine
5911 -- will not perform the check if the call appears within a default
5912 -- expression.
5916 -- In formal mode, the primitive operations of a tagged type or type
5917 -- extension do not include functions that return the tagged type.
5923 then
5927 -- Implement rule in 12.5.1 (23.3/2): In an instance, if the actual is
5928 -- class-wide and the call dispatches on result in a context that does
5929 -- not provide a tag, the call raises Program_Error.
5932 and then In_Instance
5937 then
5938 -- Verify that none of the formals are controlling
5940 declare
5944 begin
5965 -- Check the dimensions of the actuals in the call. For function calls,
5966 -- propagate the dimensions from the returned type to N.
5970 -- All done, evaluate call and deal with elaboration issues
5977 -----------------------------
5978 -- Resolve_Case_Expression --
5979 -----------------------------
5984 begin
5995 -------------------------------
5996 -- Resolve_Character_Literal --
5997 -------------------------------
6003 begin
6004 -- Verify that the character does belong to the type of the context
6009 -- Wide_Wide_Character literals must always be defined, since the set
6010 -- of wide wide character literals is complete, i.e. if a character
6011 -- literal is accepted by the parser, then it is OK for wide wide
6012 -- character (out of range character literals are rejected).
6017 -- Always accept character literal for type Any_Character, which
6018 -- occurs in error situations and in comparisons of literals, both
6019 -- of which should accept all literals.
6024 -- For Standard.Character or a type derived from it, check that the
6025 -- literal is in range.
6032 -- For Standard.Wide_Character or a type derived from it, check that the
6033 -- literal is in range.
6040 -- For Standard.Wide_Wide_Character or a type derived from it, we
6041 -- know the literal is in range, since the parser checked!
6046 -- If the entity is already set, this has already been resolved in a
6047 -- generic context, or comes from expansion. Nothing else to do.
6052 -- Otherwise we have a user defined character type, and we can use the
6053 -- standard visibility mechanisms to locate the referenced entity.
6055 else
6068 -- If we fall through, then the literal does not match any of the
6069 -- entries of the enumeration type. This isn't just a constraint error
6070 -- situation, it is an illegality (see RM 4.2).
6072 Error_Msg_NE
6076 ---------------------------
6077 -- Resolve_Comparison_Op --
6078 ---------------------------
6080 -- Context requires a boolean type, and plays no role in resolution.
6081 -- Processing identical to that for equality operators. The result type is
6082 -- the base type, which matters when pathological subtypes of booleans with
6083 -- limited ranges are used.
6090 begin
6091 -- If this is an intrinsic operation which is not predefined, use the
6092 -- types of its declared arguments to resolve the possibly overloaded
6093 -- operands. Otherwise the operands are unambiguous and specify the
6094 -- expected type.
6099 else
6110 -- Skip remaining processing if already set to Any_Type
6116 -- Deal with other error cases
6120 T = Any_Character
6121 then
6124 else
6132 -- Resolve the operands if types OK
6141 -- In SPARK, ordering operators <, <=, >, >= are not defined for Boolean
6142 -- types or array types except String.
6145 Check_SPARK_Restriction
6150 then
6151 Check_SPARK_Restriction
6155 -- Check comparison on unordered enumeration
6161 -- Evaluate the relation (note we do this after the above check since
6162 -- this Eval call may change N to True/False.
6168 -----------------------------------------
6169 -- Resolve_Discrete_Subtype_Indication --
6170 -----------------------------------------
6172 procedure Resolve_Discrete_Subtype_Indication
6175 is
6179 begin
6187 else
6197 Error_Msg_NE
6200 -- Rewrite the constraint as a range of Typ
6201 -- to allow compilation to proceed further.
6213 else
6217 -- Additionally, we must check that the bounds are compatible
6218 -- with the given subtype, which might be different from the
6219 -- type of the context.
6223 -- ??? If the above check statically detects a Constraint_Error
6224 -- it replaces the offending bound(s) of the range R with a
6225 -- Constraint_Error node. When the itype which uses these bounds
6226 -- is frozen the resulting call to Duplicate_Subexpr generates
6227 -- a new temporary for the bounds.
6229 -- Unfortunately there are other itypes that are also made depend
6230 -- on these bounds, so when Duplicate_Subexpr is called they get
6231 -- a forward reference to the newly created temporaries and Gigi
6232 -- aborts on such forward references. This is probably sign of a
6233 -- more fundamental problem somewhere else in either the order of
6234 -- itype freezing or the way certain itypes are constructed.
6236 -- To get around this problem we call Remove_Side_Effects right
6237 -- away if either bounds of R are a Constraint_Error.
6239 declare
6243 begin
6259 -------------------------
6260 -- Resolve_Entity_Name --
6261 -------------------------
6263 -- Used to resolve identifiers and expanded names
6268 begin
6269 -- If garbage from errors, set to Any_Type and return
6276 -- Replace named numbers by corresponding literals. Note that this is
6277 -- the one case where Resolve_Entity_Name must reset the Etype, since
6278 -- it is currently marked as universal.
6288 -- For enumeration literals, we need to make sure that a proper style
6289 -- check is done, since such literals are overloaded, and thus we did
6290 -- not do a style check during the first phase of analysis.
6296 -- Case of subtype name appearing as an operand in expression
6300 -- Allow use of subtype if it is a concurrent type where we are
6301 -- currently inside the body. This will eventually be expanded into a
6302 -- call to Self (for tasks) or _object (for protected objects). Any
6303 -- other use of a subtype is invalid.
6307 then
6310 -- Any other use is an error
6312 else
6313 Error_Msg_N
6317 -- Check discriminant use if entity is discriminant in current scope,
6318 -- i.e. discriminant of record or concurrent type currently being
6319 -- analyzed. Uses in corresponding body are unrestricted.
6324 then
6327 -- A parameterless generic function cannot appear in a context that
6328 -- requires resolution.
6339 then
6342 -- In all other cases, just do the possible static evaluation
6344 else
6345 -- A deferred constant that appears in an expression must have a
6346 -- completion, unless it has been removed by in-place expansion of
6347 -- an aggregate.
6353 and then not In_Spec_Expression
6355 then
6359 then
6361 else
6362 Error_Msg_N (
6371 -------------------
6372 -- Resolve_Entry --
6373 -------------------
6385 -- If the bounds of the entry family being called depend on task
6386 -- discriminants, build a new index subtype where a discriminant is
6387 -- replaced with the value of the discriminant of the target task.
6388 -- The target task is the prefix of the entry name in the call.
6390 -----------------------
6391 -- Actual_Index_Type --
6392 -----------------------
6402 -- If the bound is given by a discriminant, replace with a reference
6403 -- to the discriminant of the same name in the target task. If the
6404 -- entry name is the target of a requeue statement and the entry is
6405 -- in the current protected object, the bound to be used is the
6406 -- discriminal of the object (see Apply_Range_Checks for details of
6407 -- the transformation).
6409 -----------------------------
6410 -- Actual_Discriminant_Ref --
6411 -----------------------------
6417 begin
6422 then
6428 then
6429 -- Note: here Bound denotes a discriminant of the corresponding
6430 -- record type tskV, whose discriminal is a formal of the
6431 -- init-proc tskVIP. What we want is the body discriminal,
6432 -- which is associated to the discriminant of the original
6433 -- concurrent type tsk.
6435 return New_Occurrence_Of
6438 else
6439 Ref :=
6449 -- Start of processing for Actual_Index_Type
6451 begin
6454 then
6457 else
6471 -- Start of processing of Resolve_Entry
6473 begin
6474 -- Find name of entry being called, and resolve prefix of name with its
6475 -- own type. The prefix can be overloaded, and the name and signature of
6476 -- the entry must be taken into account.
6480 -- Case of dealing with entry family within the current tasks
6484 else
6490 -- Entry call to an entry (or entry family) in the current task. This
6491 -- is legal even though the task will deadlock. Rewrite as call to
6492 -- current task.
6494 -- This can also be a call to an entry in an enclosing task. If this
6495 -- is a single task, we have to retrieve its name, because the scope
6496 -- of the entry is the task type, not the object. If the enclosing
6497 -- task is a task type, the identity of the task is given by its own
6498 -- self variable.
6500 -- Finally this can be a requeue on an entry of the same task or
6501 -- protected object.
6508 then
6509 -- S is an enclosing task or protected object. The concurrent
6510 -- declaration has been converted into a type declaration, and
6511 -- the object itself has an object declaration that follows
6512 -- the type in the same declarative part.
6524 -- Call to current task. Will be transformed into call to Self
6531 New_N :=
6534 Selector_Name =>
6541 then
6542 -- Use the entry name (which must be unique at this point) to find
6543 -- the prefix that returns the corresponding task/protected type.
6545 declare
6551 begin
6573 -- Up to this point the expression could have been the actual in a
6574 -- simple entry call, and be given by a named association.
6578 else
6584 ------------------------
6585 -- Resolve_Entry_Call --
6586 ------------------------
6598 begin
6599 -- We kill all checks here, because it does not seem worth the effort to
6600 -- do anything better, an entry call is a big operation.
6602 Kill_All_Checks;
6604 -- Processing of the name is similar for entry calls and protected
6605 -- operation calls. Once the entity is determined, we can complete
6606 -- the resolution of the actuals.
6608 -- The selector may be overloaded, in the case of a protected object
6609 -- with overloaded functions. The type of the context is used for
6610 -- resolution.
6615 then
6616 declare
6620 begin
6639 -- Simple entry call
6647 -- Call to member of entry family
6654 -- We cannot in general check the maximum depth of protected entry calls
6655 -- at compile time. But we can tell that any protected entry call at all
6656 -- violates a specified nesting depth of zero.
6662 -- Use context type to disambiguate a protected function that can be
6663 -- called without actuals and that returns an array type, and where the
6664 -- argument list may be an indexing of the returned value.
6669 and then
6675 and then
6676 Covers
6679 then
6680 declare
6683 begin
6684 Index_Node :=
6686 Prefix =>
6690 -- Since we are correcting a node classification error made by the
6691 -- parser, we call Replace rather than Rewrite.
6704 then
6705 -- Rewrite as call to the precondition wrapper, adding the task
6706 -- object to the list of actuals. If the call is to a member of an
6707 -- entry family, include the index as well.
6709 declare
6713 begin
6722 New_Call :=
6724 Name =>
6733 -- The operation name may have been overloaded. Order the actuals
6734 -- according to the formals of the resolved entity, and set the return
6735 -- type to that of the operation.
6746 -- Create a call reference to the entry
6754 -- Verify that a procedure call cannot masquerade as an entry
6755 -- call where an entry call is expected.
6760 then
6765 then
6770 then
6775 -- After resolution, entry calls and protected procedure calls are
6776 -- changed into entry calls, for expansion. The structure of the node
6777 -- does not change, so it can safely be done in place. Protected
6778 -- function calls must keep their structure because they are
6779 -- subexpressions.
6783 -- A protected operation that is not a function may modify the
6784 -- corresponding object, and cannot apply to a constant. If this
6785 -- is an internal call, the prefix is the type itself.
6791 then
6792 Error_Msg_N
6794 Entry_Name);
6808 -- Protected functions can return on the secondary stack, in which
6809 -- case we must trigger the transient scope mechanism.
6811 elsif Full_Expander_Active
6813 then
6818 -------------------------
6819 -- Resolve_Equality_Op --
6820 -------------------------
6822 -- Both arguments must have the same type, and the boolean context does
6823 -- not participate in the resolution. The first pass verifies that the
6824 -- interpretation is not ambiguous, and the type of the left argument is
6825 -- correctly set, or is Any_Type in case of ambiguity. If both arguments
6826 -- are strings or aggregates, allocators, or Null, they are ambiguous even
6827 -- though they carry a single (universal) type. Diagnose this case here.
6835 -- The resolution rule for if expressions requires that each such must
6836 -- have a unique type. This means that if several dependent expressions
6837 -- are of a non-null anonymous access type, and the context does not
6838 -- impose an expected type (as can be the case in an equality operation)
6839 -- the expression must be rejected.
6842 -- Attempt to explain the nature of a redundant comparison with True. If
6843 -- the expression N is too complex, this routine issues a general error
6844 -- message.
6847 -- In the case of allocators and access attributes, the context must
6848 -- provide an indication of the specific access type to be used. If
6849 -- one operand is of such a "generic" access type, check whether there
6850 -- is a specific visible access type that has the same designated type.
6851 -- This is semantically dubious, and of no interest to any real code,
6852 -- but c48008a makes it all worthwhile.
6854 -------------------------
6855 -- Check_If_Expression --
6856 -------------------------
6862 begin
6869 then
6875 ------------------------
6876 -- Explain_Redundancy --
6877 ------------------------
6884 begin
6887 -- Strip the operand down to an entity
6889 loop
6892 else
6897 -- The construct denotes an entity
6902 -- Do not generate an error message when the comparison is done
6903 -- against the enumeration literal Standard.True.
6907 -- Build a customized error message
6934 -- The construct is too complex to disect, issue a general message
6936 else
6941 -----------------------------
6942 -- Find_Unique_Access_Type --
6943 -----------------------------
6950 begin
6952 E_Access_Attribute_Type)
6953 then
6957 E_Access_Attribute_Type)
6958 then
6960 else
6972 then
6985 -- Start of processing for Resolve_Equality_Op
6987 begin
6998 T = Any_Character
6999 then
7002 else
7011 then
7020 -- If expressions must have a single type, and if the context does
7021 -- not impose one the dependent expressions cannot be anonymous
7022 -- access types.
7024 -- Why no similar processing for case expressions???
7028 E_Anonymous_Access_Subprogram_Type)
7030 E_Anonymous_Access_Subprogram_Type)
7031 then
7039 -- In SPARK, equality operators = and /= for array types other than
7040 -- String are only defined when, for each index position, the
7041 -- operands have equal static bounds.
7045 -- Protect call to Matching_Static_Array_Bounds to avoid costly
7046 -- operation if not needed.
7054 then
7055 Check_SPARK_Restriction
7060 -- If the unique type is a class-wide type then it will be expanded
7061 -- into a dispatching call to the predefined primitive. Therefore we
7062 -- check here for potential violation of such restriction.
7068 if Warn_On_Redundant_Constructs
7073 then
7074 Error_Msg_N -- CODEFIX
7084 -- If this is an inequality, it may be the implicit inequality
7085 -- created for a user-defined operation, in which case the corres-
7086 -- ponding equality operation is not intrinsic, and the operation
7087 -- cannot be constant-folded. Else fold.
7092 or else Is_Intrinsic_Subprogram
7094 then
7100 then
7104 -- Ada 2005: If one operand is an anonymous access type, convert the
7105 -- other operand to it, to ensure that the underlying types match in
7106 -- the back-end. Same for access_to_subprogram, and the conversion
7107 -- verifies that the types are subtype conformant.
7109 -- We apply the same conversion in the case one of the operands is a
7110 -- private subtype of the type of the other.
7112 -- Why the Expander_Active test here ???
7114 if Full_Expander_Active
7115 and then
7117 E_Anonymous_Access_Subprogram_Type)
7119 then
7139 ----------------------------------
7140 -- Resolve_Explicit_Dereference --
7141 ----------------------------------
7149 -- The candidate prefix type, if overloaded
7154 begin
7160 -- Use the context type to select the prefix that has the correct
7161 -- designated type. Keep the first match, which will be the inner-
7162 -- most.
7169 then
7174 -- Remove access types that do not match, but preserve access
7175 -- to subprogram interpretations, in case a further dereference
7176 -- is needed (see below).
7189 else
7190 -- If no interpretation covers the designated type of the prefix,
7191 -- this is the pathological case where not all implementations of
7192 -- the prefix allow the interpretation of the node as a call. Now
7193 -- that the expected type is known, Remove other interpretations
7194 -- from prefix, rewrite it as a call, and resolve again, so that
7195 -- the proper call node is generated.
7206 New_N :=
7208 Name =>
7219 -- If not overloaded, resolve P with its own type
7221 else
7229 -- If the designated type is a packed unconstrained array type, and the
7230 -- explicit dereference is not in the context of an attribute reference,
7231 -- then we must compute and set the actual subtype, since it is needed
7232 -- by Gigi. The reason we exclude the attribute case is that this is
7233 -- handled fine by Gigi, and in fact we use such attributes to build the
7234 -- actual subtype. We also exclude generated code (which builds actual
7235 -- subtypes directly if they are needed).
7242 then
7246 -- Note: No Eval processing is required for an explicit dereference,
7247 -- because such a name can never be static.
7251 -------------------------------------
7252 -- Resolve_Expression_With_Actions --
7253 -------------------------------------
7256 begin
7260 ---------------------------
7261 -- Resolve_If_Expression --
7262 ---------------------------
7271 begin
7276 -- When the "then" expression is of a scalar subtype different from the
7277 -- result subtype, then insert a conversion to ensure the generation of
7278 -- a constraint check. The same is done for the else part below, again
7279 -- comparing subtypes rather than base types.
7283 then
7288 -- If ELSE expression present, just resolve using the determined type
7296 then
7301 -- If no ELSE expression is present, root type must be Standard.Boolean
7302 -- and we provide a Standard.True result converted to the appropriate
7303 -- Boolean type (in case it is a derived boolean type).
7306 Else_Expr :=
7311 else
7320 -------------------------------
7321 -- Resolve_Indexed_Component --
7322 -------------------------------
7330 begin
7333 -- Use the context type to select the prefix that yields the correct
7334 -- component type.
7336 declare
7343 begin
7350 and then
7351 Covers
7354 then
7363 else
7369 else
7380 else
7387 -- If prefix is access type, dereference to get real array type.
7388 -- Note: we do not apply an access check because the expander always
7389 -- introduces an explicit dereference, and the check will happen there.
7395 -- If name was overloaded, set component type correctly now
7396 -- If a misplaced call to an entry family (which has no index types)
7397 -- return. Error will be diagnosed from calling context.
7401 else
7408 -- The prefix may have resolved to a string literal, in which case its
7409 -- etype has a special representation. This is only possible currently
7410 -- if the prefix is a static concatenation, written in functional
7411 -- notation.
7416 else
7423 else
7434 -- Do not generate the warning on suspicious index if we are analyzing
7435 -- package Ada.Tags; otherwise we will report the warning with the
7436 -- Prims_Ptr field of the dispatch table.
7439 or else not
7441 Ada_Tags)
7442 then
7447 -- If the array type is atomic, and is packed, and we are in a left side
7448 -- context, then this is worth a warning, since we have a situation
7449 -- where the access to the component may cause extra read/writes of
7450 -- the atomic array object, which could be considered unexpected.
7458 then
7466 -----------------------------
7467 -- Resolve_Integer_Literal --
7468 -----------------------------
7471 begin
7476 --------------------------------
7477 -- Resolve_Intrinsic_Operator --
7478 --------------------------------
7488 -- If the operand is a literal, it cannot be the expression in a
7489 -- conversion. Use a qualified expression instead.
7494 begin
7496 Res :=
7502 else
7509 -- Start of processing for Resolve_Intrinsic_Operator
7511 begin
7512 -- We must preserve the original entity in a generic setting, so that
7513 -- the legality of the operation can be verified in an instance.
7528 -- If the result or operand types are private, rewrite with unchecked
7529 -- conversions on the operands and the result, to expose the proper
7530 -- underlying numeric type.
7535 then
7537 -- Unchecked_Convert_To (Btyp, Left_Opnd (N));
7538 -- What on earth is this commented out fragment of code???
7542 else
7563 then
7564 -- Add explicit conversion where needed, and save interpretations in
7565 -- case operands are overloaded. If the context is a VMS operation,
7566 -- assert that the conversion is legal (the operands have the proper
7567 -- types to select the VMS intrinsic). Note that in rare cases the
7568 -- VMS operators may be visible, but the default System is being used
7569 -- and Address is a private type.
7580 else
7590 else
7600 else
7605 --------------------------------------
7606 -- Resolve_Intrinsic_Unary_Operator --
7607 --------------------------------------
7609 procedure Resolve_Intrinsic_Unary_Operator
7612 is
7617 begin
7636 else
7641 ------------------------
7642 -- Resolve_Logical_Op --
7643 ------------------------
7648 begin
7651 -- Predefined operations on scalar types yield the base type. On the
7652 -- other hand, logical operations on arrays yield the type of the
7653 -- arguments (and the context).
7657 else
7661 -- OK if this is a VMS-specific intrinsic operation
7666 -- The following test is required because the operands of the operation
7667 -- may be literals, in which case the resulting type appears to be
7668 -- compatible with a signed integer type, when in fact it is compatible
7669 -- only with modular types. If the context itself is universal, the
7670 -- operation is illegal.
7678 Error_Msg_N
7686 then
7690 -- Replace AND by AND THEN, or OR by OR ELSE, if Short_Circuit_And_Or
7691 -- is active and the result type is standard Boolean (do not mess with
7692 -- ops that return a nonstandard Boolean type, because something strange
7693 -- is going on).
7695 -- Note: you might expect this replacement to be done during expansion,
7696 -- but that doesn't work, because when the pragma Short_Circuit_And_Or
7697 -- is used, no part of the right operand of an "and" or "or" operator
7698 -- should be executed if the left operand would short-circuit the
7699 -- evaluation of the corresponding "and then" or "or else". If we left
7700 -- the replacement to expansion time, then run-time checks associated
7701 -- with such operands would be evaluated unconditionally, due to being
7702 -- before the condition prior to the rewriting as short-circuit forms
7703 -- during expansion.
7705 if Short_Circuit_And_Or
7708 then
7716 -- Case of OR changed to OR ELSE
7718 else
7726 -- Return now, since analysis of the rewritten ops will take care of
7727 -- other reference bookkeeping and expression folding.
7742 -- In SPARK, logical operations AND, OR and XOR for arrays are defined
7743 -- only when both operands have same static lower and higher bounds. Of
7744 -- course the types have to match, so only check if operands are
7745 -- compatible and the node itself has no errors.
7749 then
7750 declare
7754 begin
7755 -- Protect call to Matching_Static_Array_Bounds to avoid costly
7756 -- operation if not needed.
7763 then
7764 Check_SPARK_Restriction
7773 ---------------------------
7774 -- Resolve_Membership_Op --
7775 ---------------------------
7777 -- The context can only be a boolean type, and does not determine the
7778 -- arguments. Arguments should be unambiguous, but the preference rule for
7779 -- universal types applies.
7789 -- Analysis has determined a unique type for the left operand. Use it to
7790 -- resolve the disjuncts.
7792 ----------------------------
7793 -- Resolve_Set_Membership --
7794 ----------------------------
7800 begin
7806 -- Alternative is an expression, a range
7807 -- or a subtype mark.
7811 then
7818 -- Check for duplicates for discrete case
7821 declare
7830 begin
7831 -- Loop checking duplicates. This is quadratic, but giant sets
7832 -- are unlikely in this context so it's a reasonable choice.
7839 N_Character_Literal)
7841 then
7859 -- Start of processing for Resolve_Membership_Op
7861 begin
7867 Resolve_Set_Membership;
7872 and then
7874 or else
7877 then
7880 -- Ada 2005 (AI-251): Support the following case:
7882 -- type I is interface;
7883 -- type T is tagged ...
7885 -- function Test (O : I'Class) is
7886 -- begin
7887 -- return O in T'Class.
7888 -- end Test;
7890 -- In this case we have nothing else to do. The membership test will be
7891 -- done at run time.
7898 then
7900 else
7904 -- If mixed-mode operations are present and operands are all literal,
7905 -- the only interpretation involves Duration, which is probably not
7906 -- the intention of the programmer.
7921 then
7927 else
7936 ------------------
7937 -- Resolve_Null --
7938 ------------------
7943 begin
7944 -- Handle restriction against anonymous null access values This
7945 -- restriction can be turned off using -gnatdj.
7947 -- Ada 2005 (AI-231): Remove restriction
7950 and then not Debug_Flag_J
7953 then
7954 -- In the common case of a call which uses an explicitly null value
7955 -- for an access parameter, give specialized error message.
7958 Error_Msg_N
7961 -- Standard message for all other cases (are there any?)
7963 else
7964 Error_Msg_N
7969 -- Ada 2005 (AI-231): Generate the null-excluding check in case of
7970 -- assignment to a null-excluding object
7975 then
7977 Insert_Action
7982 else
7989 -- In a distributed context, null for a remote access to subprogram may
7990 -- need to be replaced with a special record aggregate. In this case,
7991 -- return after having done the transformation.
7996 then
8000 -- The null literal takes its type from the context
8005 -----------------------
8006 -- Resolve_Op_Concat --
8007 -----------------------
8011 -- We wish to avoid deep recursion, because concatenations are often
8012 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
8013 -- operands nonrecursively until we find something that is not a simple
8014 -- concatenation (A in this case). We resolve that, and then walk back
8015 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
8016 -- to do the rest of the work at each level. The Parent pointers allow
8017 -- us to avoid recursion, and thus avoid running out of memory. See also
8018 -- Sem_Ch4.Analyze_Concatenation, where a similar approach is used.
8023 begin
8024 -- The following code is equivalent to:
8026 -- Resolve_Op_Concat_First (NN, Typ);
8027 -- Resolve_Op_Concat_Arg (N, ...);
8028 -- Resolve_Op_Concat_Rest (N, Typ);
8030 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
8031 -- operand is a concatenation.
8033 -- Walk down left operands
8035 loop
8044 -- Now (given the above example) NN is A&B and Op1 is A
8046 -- First resolve Op1 ...
8050 -- ... then walk NN back up until we reach N (where we started), calling
8051 -- Resolve_Op_Concat_Rest along the way.
8053 loop
8060 Check_SPARK_Restriction
8065 ---------------------------
8066 -- Resolve_Op_Concat_Arg --
8067 ---------------------------
8069 procedure Resolve_Op_Concat_Arg
8074 is
8078 begin
8080 if Is_Comp
8084 then
8086 else
8090 -- If both Array & Array and Array & Component are visible, there is a
8091 -- potential ambiguity that must be reported.
8096 then
8100 -- If the operation is user-defined and not overloaded use its
8101 -- profile. The operation may be a renaming, in which case it has
8102 -- been rewritten, and we want the original profile.
8107 then
8109 Etype
8113 -- Otherwise an aggregate may match both the array type and the
8114 -- component type.
8116 else
8121 else
8125 then
8126 declare
8131 begin
8136 -- Special-case the error message when the overloading is
8137 -- caused by a function that yields an array and can be
8138 -- called without parameters.
8143 Error_Msg_NE
8145 Error_Msg_NE
8149 else
8157 or else
8159 then
8160 Error_Msg_N -- CODEFIX
8178 else
8183 else
8187 -- Concatenation is restricted in SPARK: each operand must be either a
8188 -- string literal, the name of a string constant, a static character or
8189 -- string expression, or another concatenation. Arg cannot be a
8190 -- concatenation here as callers of Resolve_Op_Concat_Arg call it
8191 -- separately on each final operand, past concatenation operations.
8195 Check_SPARK_Restriction
8203 then
8204 Check_SPARK_Restriction
8208 -- Do not issue error on an operand that is neither a character nor a
8209 -- string, as the error is issued in Resolve_Op_Concat.
8211 else
8218 -----------------------------
8219 -- Resolve_Op_Concat_First --
8220 -----------------------------
8227 begin
8228 -- The parser folds an enormous sequence of concatenations of string
8229 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
8230 -- in the right operand. If the expression resolves to a predefined "&"
8231 -- operator, all is well. Otherwise, the parser's folding is wrong, so
8232 -- we give an error. See P_Simple_Expression in Par.Ch4.
8237 then
8252 ----------------------------
8253 -- Resolve_Op_Concat_Rest --
8254 ----------------------------
8260 begin
8269 -- If this is not a static concatenation, but the result is a string
8270 -- type (and not an array of strings) ensure that static string operands
8271 -- have their subtypes properly constructed.
8275 then
8281 ----------------------
8282 -- Resolve_Op_Expon --
8283 ----------------------
8288 begin
8289 -- Catch attempts to do fixed-point exponentiation with universal
8290 -- operands, which is a case where the illegality is not caught during
8291 -- normal operator analysis.
8301 then
8310 then
8317 then
8321 -- We do the resolution using the base type, because intermediate values
8322 -- in expressions always are of the base type, not a subtype of it.
8336 -- Evaluate the exponentiation operator for dimensioned type
8339 else
8343 -- Set overflow checking bit. Much cleverer code needed here eventually
8344 -- and perhaps the Resolve routines should be separated for the various
8345 -- arithmetic operations, since they will need different processing. ???
8354 --------------------
8355 -- Resolve_Op_Not --
8356 --------------------
8362 -- This function determines if the parent node is a boolean operator or
8363 -- operation (comparison op, membership test, or short circuit form) and
8364 -- the not in question is the left operand of this operation. Note that
8365 -- if the not is in parens, then false is returned.
8367 -----------------------
8368 -- Parent_Is_Boolean --
8369 -----------------------
8372 begin
8376 else
8378 when N_Op_And |
8379 N_Op_Eq |
8380 N_Op_Ge |
8381 N_Op_Gt |
8382 N_Op_Le |
8383 N_Op_Lt |
8384 N_Op_Ne |
8385 N_Op_Or |
8386 N_Op_Xor |
8387 N_In |
8388 N_Not_In |
8389 N_And_Then |
8390 N_Or_Else =>
8400 -- Start of processing for Resolve_Op_Not
8402 begin
8403 -- Predefined operations on scalar types yield the base type. On the
8404 -- other hand, logical operations on arrays yield the type of the
8405 -- arguments (and the context).
8409 else
8416 -- Straightforward case of incorrect arguments
8423 -- Special case of probable missing parens
8427 Error_Msg_N
8430 else
8431 Error_Msg_N
8438 -- OK resolution of NOT
8440 else
8441 -- Warn if non-boolean types involved. This is a case like not a < b
8442 -- where a and b are modular, where we will get (not a) < b and most
8443 -- likely not (a < b) was intended.
8445 if Warn_On_Questionable_Missing_Parens
8447 and then Parent_Is_Boolean
8448 then
8452 -- Warn on double negation if checking redundant constructs
8454 if Warn_On_Redundant_Constructs
8459 then
8463 -- Complete resolution and evaluation of NOT
8473 -----------------------------
8474 -- Resolve_Operator_Symbol --
8475 -----------------------------
8477 -- Nothing to be done, all resolved already
8483 begin
8487 ----------------------------------
8488 -- Resolve_Qualified_Expression --
8489 ----------------------------------
8497 begin
8500 -- Protect call to Matching_Static_Array_Bounds to avoid costly
8501 -- operation if not needed.
8508 then
8509 Check_SPARK_Restriction
8513 -- A qualified expression requires an exact match of the type, class-
8514 -- wide matching is not allowed. However, if the qualifying type is
8515 -- specific and the expression has a class-wide type, it may still be
8516 -- okay, since it can be the result of the expansion of a call to a
8517 -- dispatching function, so we also have to check class-wideness of the
8518 -- type of the expression's original node.
8521 or else
8525 then
8529 -- If the target type is unconstrained, then we reset the type of the
8530 -- result from the type of the expression. For other cases, the actual
8531 -- subtype of the expression is the target type.
8535 then
8543 -------------------
8544 -- Resolve_Range --
8545 -------------------
8552 -- Returns True if N is of the form X'First .. X'Last where X is the
8553 -- same entity for both attributes.
8555 --------------------
8556 -- First_Last_Ref --
8557 --------------------
8563 begin
8568 then
8569 declare
8572 begin
8576 then
8585 -- Start of processing for Resolve_Range
8587 begin
8592 -- Check for inappropriate range on unordered enumeration type
8596 -- Exclude X'First .. X'Last if X is the same entity for both
8598 and then not First_Last_Ref
8599 then
8606 -- We have to check the bounds for being within the base range as
8607 -- required for a non-static context. Normally this is automatic and
8608 -- done as part of evaluating expressions, but the N_Range node is an
8609 -- exception, since in GNAT we consider this node to be a subexpression,
8610 -- even though in Ada it is not. The circuit in Sem_Eval could check for
8611 -- this, but that would put the test on the main evaluation path for
8612 -- expressions.
8617 -- Check for an ambiguous range over character literals. This will
8618 -- happen with a membership test involving only literals.
8626 -- If bounds are static, constant-fold them, so size computations are
8627 -- identical between front-end and back-end. Do not perform this
8628 -- transformation while analyzing generic units, as type information
8629 -- would be lost when reanalyzing the constant node in the instance.
8642 --------------------------
8643 -- Resolve_Real_Literal --
8644 --------------------------
8649 begin
8650 -- Special processing for fixed-point literals to make sure that the
8651 -- value is an exact multiple of small where this is required. We skip
8652 -- this for the universal real case, and also for generic types.
8658 then
8659 declare
8666 begin
8667 -- Case of literal is not an exact multiple of the Small
8671 -- For a source program literal for a decimal fixed-point type,
8672 -- this is statically illegal (RM 4.9(36)).
8677 then
8681 -- Generate a warning if literal from source
8684 and then Warn_On_Bad_Fixed_Value
8685 then
8686 Error_Msg_N
8688 N);
8691 -- Replace literal by a value that is the exact representation
8692 -- of a value of the type, i.e. a multiple of the small value,
8693 -- by truncation, since Machine_Rounds is false for all GNAT
8694 -- fixed-point types (RM 4.9(38)).
8704 -- In all cases, set the corresponding integer field
8710 -- Now replace the actual type by the expected type as usual
8716 -----------------------
8717 -- Resolve_Reference --
8718 -----------------------
8723 begin
8724 -- Replace general access with specific type
8732 -- If we are taking the reference of a volatile entity, then treat it as
8733 -- a potential modification of this entity. This is too conservative,
8734 -- but necessary because remove side effects can cause transformations
8735 -- of normal assignments into reference sequences that otherwise fail to
8736 -- notice the modification.
8743 --------------------------------
8744 -- Resolve_Selected_Component --
8745 --------------------------------
8760 -- Check whether this is the initialization of a component within an
8761 -- init proc (by assignment or call to another init proc). If true,
8762 -- there is no need for a discriminant check.
8764 --------------------
8765 -- Init_Component --
8766 --------------------
8769 begin
8770 return Inside_Init_Proc
8776 -- Start of processing for Resolve_Selected_Component
8778 begin
8781 -- Use the context type to select the prefix that has a selector
8782 -- of the correct name and type.
8790 else
8794 -- Locate selected component. For a private prefix the selector
8795 -- can denote a discriminant.
8799 -- The visible components of a class-wide type are those of
8800 -- the root type.
8810 then
8817 else
8821 Error_Msg_N
8826 else
8829 -- There may be an implicit dereference. Retrieve
8830 -- designated record type.
8834 else
8840 -- Resolution chooses the new interpretation.
8841 -- Find the component with the right name.
8846 loop
8867 else
8868 -- Resolve prefix with its type
8873 -- Generate cross-reference. We needed to wait until full overloading
8874 -- resolution was complete to do this, since otherwise we can't tell if
8875 -- we are an lvalue or not.
8879 else
8883 -- If prefix is an access type, the node will be transformed into an
8884 -- explicit dereference during expansion. The type of the node is the
8885 -- designated type of that of the prefix.
8890 else
8899 and then not Init_Component
8900 then
8908 -- If the prefix is a record conversion, this may be a renamed
8909 -- discriminant whose bounds differ from those of the original
8910 -- one, so we must ensure that a range check is performed.
8915 then
8919 -- Note: No Eval processing is required, because the prefix is of a
8920 -- record type, or protected type, and neither can possibly be static.
8922 -- If the array type is atomic, and is packed, and we are in a left side
8923 -- context, then this is worth a warning, since we have a situation
8924 -- where the access to the component may cause extra read/writes of the
8925 -- atomic array object, which could be considered unexpected.
8933 then
8934 Error_Msg_N
8936 Error_Msg_N
8943 -------------------
8944 -- Resolve_Shift --
8945 -------------------
8952 begin
8953 -- We do the resolution using the base type, because intermediate values
8954 -- in expressions always are of the base type, not a subtype of it.
8967 ---------------------------
8968 -- Resolve_Short_Circuit --
8969 ---------------------------
8976 begin
8980 -- Check for issuing warning for always False assert/check, this happens
8981 -- when assertions are turned off, in which case the pragma Assert/Check
8982 -- was transformed into:
8984 -- if False and then <condition> then ...
8986 -- and we detect this pattern
8988 if Warn_On_Assertion_Failure
8995 then
8996 declare
8999 begin
9000 -- Special handling of Asssert pragma
9004 then
9005 declare
9007 Original_Node
9008 (Expression
9011 begin
9012 -- Don't warn if original condition is explicit False,
9013 -- since obviously the failure is expected in this case.
9017 then
9020 -- Issue warning. We do not want the deletion of the
9021 -- IF/AND-THEN to take this message with it. We achieve this
9022 -- by making sure that the expanded code points to the Sloc
9023 -- of the expression, not the original pragma.
9025 else
9026 -- Note: Use Error_Msg_F here rather than Error_Msg_N.
9027 -- The source location of the expression is not usually
9028 -- the best choice here. For example, it gets located on
9029 -- the last AND keyword in a chain of boolean expressiond
9030 -- AND'ed together. It is best to put the message on the
9031 -- first character of the assertion, which is the effect
9032 -- of the First_Node call here.
9034 Error_Msg_F
9036 Expression
9041 -- Similar processing for Check pragma
9045 then
9046 -- Don't want to warn if original condition is explicit False
9048 declare
9050 Original_Node
9051 (Expression
9053 begin
9056 then
9059 -- Post warning
9061 else
9062 -- Again use Error_Msg_F rather than Error_Msg_N, see
9063 -- comment above for an explanation of why we do this.
9065 Error_Msg_F
9067 Expression
9075 -- Continue with processing of short circuit
9084 -------------------
9085 -- Resolve_Slice --
9086 -------------------
9094 begin
9097 -- Use the context type to select the prefix that yields the correct
9098 -- array type.
9100 declare
9107 begin
9115 then
9123 else
9128 else
9139 else
9149 -- If the prefix is an access to an unconstrained array, we must use
9150 -- the actual subtype of the object to perform the index checks. The
9151 -- object denoted by the prefix is implicit in the node, so we build
9152 -- an explicit representation for it in order to compute the actual
9153 -- subtype.
9158 declare
9162 begin
9173 then
9176 -- If the name is a selected component that depends on discriminants,
9177 -- build an actual subtype for it. This can happen only when the name
9178 -- itself is overloaded; otherwise the actual subtype is created when
9179 -- the selected component is analyzed.
9182 and then Full_Analysis
9184 then
9185 declare
9188 begin
9193 -- Maybe this should just be "else", instead of checking for the
9194 -- specific case of slice??? This is needed for the case where the
9195 -- prefix is an Image attribute, which gets expanded to a slice, and so
9196 -- has a constrained subtype which we want to use for the slice range
9197 -- check applied below (the range check won't get done if the
9198 -- unconstrained subtype of the 'Image is used).
9204 -- If name was overloaded, set slice type correctly now
9208 -- If the range is specified by a subtype mark, no resolution is
9209 -- necessary. Else resolve the bounds, and apply needed checks.
9214 else
9222 -- Ensure that side effects in the bounds are properly handled
9227 -- Do not apply the range check to nodes associated with the
9228 -- frontend expansion of the dispatch table. We first check
9229 -- if Ada.Tags is already loaded to avoid the addition of an
9230 -- undesired dependence on such run-time unit.
9232 if not Tagged_Type_Expansion
9233 or else not
9239 then
9247 -- Check bad use of type with predicates
9250 Bad_Predicated_Subtype_Use
9254 -- Otherwise here is where we check suspicious indexes
9265 ----------------------------
9266 -- Resolve_String_Literal --
9267 ----------------------------
9278 begin
9279 -- For a string appearing in a concatenation, defer creation of the
9280 -- string_literal_subtype until the end of the resolution of the
9281 -- concatenation, because the literal may be constant-folded away. This
9282 -- is a useful optimization for long concatenation expressions.
9284 -- If the string is an aggregate built for a single character (which
9285 -- happens in a non-static context) or a is null string to which special
9286 -- checks may apply, we build the subtype. Wide strings must also get a
9287 -- string subtype if they come from a one character aggregate. Strings
9288 -- generated by attributes might be static, but it is often hard to
9289 -- determine whether the enclosing context is static, so we generate
9290 -- subtypes for them as well, thus losing some rarer optimizations ???
9291 -- Same for strings that come from a static conversion.
9293 Need_Check :=
9302 -- If the resolving type is itself a string literal subtype, we can just
9303 -- reuse it, since there is no point in creating another.
9309 and then not Need_Check
9311 N_Attribute_Reference,
9312 N_Qualified_Expression,
9313 N_Type_Conversion)
9314 then
9317 -- Otherwise we must create a string literal subtype. Note that the
9318 -- whole idea of string literal subtypes is simply to avoid the need
9319 -- for building a full fledged array subtype for each literal.
9321 else
9327 or else Need_Check
9328 then
9335 then
9341 -- The validity of a null string has been checked in the call to
9342 -- Eval_String_Literal.
9347 -- Always accept string literal with component type Any_Character, which
9348 -- occurs in error situations and in comparisons of literals, both of
9349 -- which should accept all literals.
9354 -- If the type is bit-packed, then we always transform the string
9355 -- literal into a full fledged aggregate.
9360 -- Deal with cases of Wide_Wide_String, Wide_String, and String
9362 else
9363 -- For Standard.Wide_Wide_String, or any other type whose component
9364 -- type is Standard.Wide_Wide_Character, we know that all the
9365 -- characters in the string must be acceptable, since the parser
9366 -- accepted the characters as valid character literals.
9371 -- For the case of Standard.String, or any other type whose component
9372 -- type is Standard.Character, we must make sure that there are no
9373 -- wide characters in the string, i.e. that it is entirely composed
9374 -- of characters in range of type Character.
9376 -- If the string literal is the result of a static concatenation, the
9377 -- test has already been performed on the components, and need not be
9378 -- repeated.
9382 then
9386 -- If we are out of range, post error. This is one of the
9387 -- very few places that we place the flag in the middle of
9388 -- a token, right under the offending wide character. Not
9389 -- quite clear if this is right wrt wide character encoding
9390 -- sequences, but it's only an error message!
9392 Error_Msg
9399 -- For the case of Standard.Wide_String, or any other type whose
9400 -- component type is Standard.Wide_Character, we must make sure that
9401 -- there are no wide characters in the string, i.e. that it is
9402 -- entirely composed of characters in range of type Wide_Character.
9404 -- If the string literal is the result of a static concatenation,
9405 -- the test has already been performed on the components, and need
9406 -- not be repeated.
9410 then
9414 -- If we are out of range, post error. This is one of the
9415 -- very few places that we place the flag in the middle of
9416 -- a token, right under the offending wide character.
9418 -- This is not quite right, because characters in general
9419 -- will take more than one character position ???
9421 Error_Msg
9428 -- If the root type is not a standard character, then we will convert
9429 -- the string into an aggregate and will let the aggregate code do
9430 -- the checking. Standard Wide_Wide_Character is also OK here.
9432 else
9436 -- See if the component type of the array corresponding to the string
9437 -- has compile time known bounds. If yes we can directly check
9438 -- whether the evaluation of the string will raise constraint error.
9439 -- Otherwise we need to transform the string literal into the
9440 -- corresponding character aggregate and let the aggregate code do
9441 -- the checking.
9445 -- Check for the case of full range, where we are definitely OK
9451 -- Here the range is not the complete base type range, so check
9453 declare
9461 begin
9464 then
9470 then
9471 Apply_Compile_Time_Constraint_Error
9473 CE_Range_Check_Failed,
9484 -- If we got here we meed to transform the string literal into the
9485 -- equivalent qualified positional array aggregate. This is rather
9486 -- heavy artillery for this situation, but it is hard work to avoid.
9488 declare
9493 begin
9494 -- Build the character literals, we give them source locations that
9495 -- correspond to the string positions, which is a bit tricky given
9496 -- the possible presence of wide character escape sequences.
9510 -- Should we have a call to Skip_Wide here ???
9512 -- ??? else
9513 -- Skip_Wide (P);
9521 Expression =>
9528 -----------------------------
9529 -- Resolve_Subprogram_Info --
9530 -----------------------------
9533 begin
9537 -----------------------------
9538 -- Resolve_Type_Conversion --
9539 -----------------------------
9551 -- Set to False to suppress cases where we want to suppress the test
9552 -- for redundancy to avoid possible false positives on this warning.
9554 begin
9555 if not Conv_OK
9557 then
9561 -- If the Operand Etype is Universal_Fixed, then the conversion is
9562 -- never redundant. We need this check because by the time we have
9563 -- finished the rather complex transformation, the conversion looks
9564 -- redundant when it is not.
9569 -- If the operand is marked as Any_Fixed, then special processing is
9570 -- required. This is also a case where we suppress the test for a
9571 -- redundant conversion, since most certainly it is not redundant.
9576 -- Mixed-mode operation involving a literal. Context must be a fixed
9577 -- type which is applied to the literal subsequently.
9585 or else
9587 then
9588 -- Return if expression is ambiguous
9593 -- If nothing else, the available fixed type is Duration
9595 else
9599 -- Resolve the real operand with largest available precision
9603 else
9609 -- If the operand is a literal (it could be a non-static and
9610 -- illegal exponentiation) check whether the use of Duration
9611 -- is potentially inaccurate.
9616 then
9617 Error_Msg_N
9620 Error_Msg_N
9627 then
9630 else
9639 -- In SPARK, a type conversion between array types should be restricted
9640 -- to types which have matching static bounds.
9642 -- Protect call to Matching_Static_Array_Bounds to avoid costly
9643 -- operation if not needed.
9650 then
9651 Check_SPARK_Restriction
9655 -- In formal mode, the operand of an ancestor type conversion must be an
9656 -- object (not an expression).
9664 then
9670 -- Note: we do the Eval_Type_Conversion call before applying the
9671 -- required checks for a subtype conversion. This is important, since
9672 -- both are prepared under certain circumstances to change the type
9673 -- conversion to a constraint error node, but in the case of
9674 -- Eval_Type_Conversion this may reflect an illegality in the static
9675 -- case, and we would miss the illegality (getting only a warning
9676 -- message), if we applied the type conversion checks first.
9680 -- Even when evaluation is not possible, we may be able to simplify the
9681 -- conversion or its expression. This needs to be done before applying
9682 -- checks, since otherwise the checks may use the original expression
9683 -- and defeat the simplifications. This is specifically the case for
9684 -- elimination of the floating-point Truncation attribute in
9685 -- float-to-int conversions.
9689 -- If after evaluation we still have a type conversion, then we may need
9690 -- to apply checks required for a subtype conversion.
9692 -- Skip these type conversion checks if universal fixed operands
9693 -- operands involved, since range checks are handled separately for
9694 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
9700 then
9704 -- Issue warning for conversion of simple object to its own type. We
9705 -- have to test the original nodes, since they may have been rewritten
9706 -- by various optimizations.
9710 -- Here we test for a redundant conversion if the warning mode is
9711 -- active (and was not locally reset), and we have a type conversion
9712 -- from source not appearing in a generic instance.
9714 if Test_Redundant
9717 and then not In_Instance
9718 then
9722 -- If the node is part of a larger expression, the Target_Type
9723 -- may not be the original type of the node if the context is a
9724 -- condition. Recover original type to see if conversion is needed.
9728 then
9732 -- If we have an entity name, then give the warning if the entity
9733 -- is the right type, or if it is a loop parameter covered by the
9734 -- original type (that's needed because loop parameters have an
9735 -- odd subtype coming from the bounds).
9738 and then
9740 or else
9744 -- If not an entity, then type of expression must match
9747 then
9748 -- One more check, do not give warning if the analyzed conversion
9749 -- has an expression with non-static bounds, and the bounds of the
9750 -- target are static. This avoids junk warnings in cases where the
9751 -- conversion is necessary to establish staticness, for example in
9752 -- a case statement.
9756 then
9759 -- Finally, if this type conversion occurs in a context requiring
9760 -- a prefix, and the expression is a qualified expression then the
9761 -- type conversion is not redundant, since a qualified expression
9762 -- is not a prefix, whereas a type conversion is. For example, "X
9763 -- := T'(Funx(...)).Y;" is illegal because a selected component
9764 -- requires a prefix, but a type conversion makes it legal: "X :=
9765 -- T(T'(Funx(...))).Y;"
9767 -- In Ada 2012, a qualified expression is a name, so this idiom is
9768 -- no longer needed, but we still suppress the warning because it
9769 -- seems unfriendly for warnings to pop up when you switch to the
9770 -- newer language version.
9774 N_Indexed_Component,
9775 N_Selected_Component,
9776 N_Slice,
9777 N_Explicit_Dereference)
9778 then
9781 -- Never warn on conversion to Long_Long_Integer'Base since
9782 -- that is most likely an artifact of the extended overflow
9783 -- checking and comes from complex expanded code.
9788 -- Here we give the redundant conversion warning. If it is an
9789 -- entity, give the name of the entity in the message. If not,
9790 -- just mention the expression.
9792 -- Shoudn't we test Warn_On_Redundant_Constructs here ???
9794 else
9797 Error_Msg_NE -- CODEFIX
9800 else
9801 Error_Msg_NE
9809 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
9810 -- No need to perform any interface conversion if the type of the
9811 -- expression coincides with the target type.
9814 and then Full_Expander_Active
9816 then
9817 declare
9821 begin
9833 -- Conversion from interface type
9837 -- Ada 2005 (AI-217): Handle entities from limited views
9841 Error_Msg_NE -- CODEFIX
9844 Error_Msg_N
9846 N);
9849 and then not
9852 then
9854 Error_Msg_NE -- CODEFIX
9857 Error_Msg_N
9859 N);
9861 else
9865 -- Conversion to interface type
9869 -- Handle subtypes
9876 or else Interface_Present_In_Ancestor
9879 then
9881 else
9884 Error_Msg_N
9892 -- Ada 2012: if target type has predicates, the result requires a
9893 -- predicate check. If the context is a call to another predicate
9894 -- check we must prevent infinite recursion.
9900 or else
9902 then
9905 else
9911 ----------------------
9912 -- Resolve_Unary_Op --
9913 ----------------------
9922 begin
9925 Check_SPARK_Restriction
9929 -- Deal with intrinsic unary operators
9935 then
9940 -- Deal with universal cases
9943 or else
9945 then
9952 -- Generate warning for expressions like abs (x mod 2)
9954 if Warn_On_Redundant_Constructs
9956 then
9960 Error_Msg_N -- CODEFIX
9965 -- Deal with reference generation
9972 -- Set overflow checking bit. Much cleverer code needed here eventually
9973 -- and perhaps the Resolve routines should be separated for the various
9974 -- arithmetic operations, since they will need different processing ???
9982 -- Generate warning for expressions like -5 mod 3 for integers. No need
9983 -- to worry in the floating-point case, since parens do not affect the
9984 -- result so there is no point in giving in a warning.
9986 declare
9995 begin
9996 if Warn_On_Questionable_Missing_Parens
10000 then
10003 -- We are looking for cases where the right operand is not
10004 -- parenthesized, and is a binary operator, multiply, divide, or
10005 -- mod. These are the cases where the grouping can affect results.
10009 then
10010 -- For mod, we always give the warning, since the value is
10011 -- affected by the parenthesization (e.g. (-5) mod 315 /=
10012 -- -(5 mod 315)). But for the other cases, the only concern is
10013 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
10014 -- overflows, but (-2) * 64 does not). So we try to give the
10015 -- message only when overflow is possible.
10019 then
10024 else
10030 else
10034 -- Note that the test below is deliberately excluding the
10035 -- largest negative number, since that is a potentially
10036 -- troublesome case (e.g. -2 * x, where the result is the
10037 -- largest negative integer has an overflow with 2 * x).
10044 -- For the multiplication case, the only case we have to worry
10045 -- about is when (-a)*b is exactly the largest negative number
10046 -- so that -(a*b) can cause overflow. This can only happen if
10047 -- a is a power of 2, and more generally if any operand is a
10048 -- constant that is not a power of 2, then the parentheses
10049 -- cannot affect whether overflow occurs. We only bother to
10050 -- test the left most operand
10052 -- Loop looking at left operands for one that has known value
10059 -- Operand value of 0 or 1 skips warning
10064 -- Otherwise check power of 2, if power of 2, warn, if
10065 -- anything else, skip warning.
10067 else
10071 else
10080 -- Keep looking at left operands
10085 -- For rem or "/" we can only have a problematic situation
10086 -- if the divisor has a value of minus one or one. Otherwise
10087 -- overflow is impossible (divisor > 1) or we have a case of
10088 -- division by zero in any case.
10093 then
10097 -- If we fall through warning should be issued
10099 -- Shouldn't we test Warn_On_Questionable_Missing_Parens ???
10101 Error_Msg_N
10108 ----------------------------------
10109 -- Resolve_Unchecked_Expression --
10110 ----------------------------------
10112 procedure Resolve_Unchecked_Expression
10115 is
10116 begin
10121 ---------------------------------------
10122 -- Resolve_Unchecked_Type_Conversion --
10123 ---------------------------------------
10125 procedure Resolve_Unchecked_Type_Conversion
10128 is
10134 begin
10135 -- Resolve operand using its own type
10142 ------------------------------
10143 -- Rewrite_Operator_As_Call --
10144 ------------------------------
10151 begin
10158 New_N :=
10169 ------------------------------
10170 -- Rewrite_Renamed_Operator --
10171 ------------------------------
10173 procedure Rewrite_Renamed_Operator
10177 is
10182 begin
10183 -- Rewrite the operator node using the real operator, not its renaming.
10184 -- Exclude user-defined intrinsic operations of the same name, which are
10185 -- treated separately and rewritten as calls.
10194 -- Indicate that both the original entity and its renaming are
10195 -- referenced at this point.
10206 -- If the context type is private, add the appropriate conversions so
10207 -- that the operator is applied to the full view. This is done in the
10208 -- routines that resolve intrinsic operators.
10212 then
10214 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
10215 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
10228 -- Operator renames a user-defined operator of the same name. Use the
10229 -- original operator in the node, which is the one Gigi knows about.
10236 -----------------------
10237 -- Set_Slice_Subtype --
10238 -----------------------
10240 -- Build an implicit subtype declaration to represent the type delivered by
10241 -- the slice. This is an abbreviated version of an array subtype. We define
10242 -- an index subtype for the slice, using either the subtype name or the
10243 -- discrete range of the slice. To be consistent with index usage elsewhere
10244 -- we create a list header to hold the single index. This list is not
10245 -- otherwise attached to the syntax tree.
10256 begin
10260 else
10261 -- We force the evaluation of a range. This is definitely needed in
10262 -- the renamed case, and seems safer to do unconditionally. Note in
10263 -- any case that since we will create and insert an Itype referring
10264 -- to this range, we must make sure any side effect removal actions
10265 -- are inserted before the Itype definition.
10276 -- Take a new copy of Drange (where bounds have been rewritten to
10277 -- reference side-effect-free names). Using a separate tree ensures
10278 -- that further expansion (e.g. while rewriting a slice assignment
10279 -- into a FOR loop) does not attempt to remove side effects on the
10280 -- bounds again (which would cause the bounds in the index subtype
10281 -- definition to refer to temporaries before they are defined) (the
10282 -- reason is that some names are considered side effect free here
10283 -- for the subtype, but not in the context of a loop iteration
10284 -- scheme).
10305 -- The Etype of the existing Slice node is reset to this slice subtype.
10306 -- Its bounds are obtained from its first index.
10310 -- For packed slice subtypes, freeze immediately (except in the case of
10311 -- being in a "spec expression" where we never freeze when we first see
10312 -- the expression).
10317 -- For all other cases insert an itype reference in the slice's actions
10318 -- so that the itype is frozen at the proper place in the tree (i.e. at
10319 -- the point where actions for the slice are analyzed). Note that this
10320 -- is different from freezing the itype immediately, which might be
10321 -- premature (e.g. if the slice is within a transient scope). This needs
10322 -- to be done only if expansion is enabled.
10329 --------------------------------
10330 -- Set_String_Literal_Subtype --
10331 --------------------------------
10339 begin
10351 -- The low bound is set from the low bound of the corresponding index
10352 -- type. Note that we do not store the high bound in the string literal
10353 -- subtype, but it can be deduced if necessary from the length and the
10354 -- low bound.
10359 -- If the lower bound is not static we create a range for the string
10360 -- literal, using the index type and the known length of the literal.
10361 -- The index type is not necessarily Positive, so the upper bound is
10362 -- computed as T'Val (T'Pos (Low_Bound) + L - 1).
10364 else
10365 declare
10371 Prefix =>
10375 Left_Opnd =>
10378 Prefix =>
10380 Expressions =>
10382 Right_Opnd =>
10391 begin
10393 Set_String_Literal_Low_Bound
10396 else
10397 -- If the index type is an enumeration type, build bounds
10398 -- expression with attributes.
10400 Set_String_Literal_Low_Bound
10404 Prefix =>
10411 -- Build bona fide subtype for the string, and wrap it in an
10412 -- unchecked conversion, because the backend expects the
10413 -- String_Literal_Subtype to have a static lower bound.
10415 Index_Subtype :=
10422 -- In the context, the Index_Type may already have a constraint,
10423 -- so use common base type on string subtype. The base type may
10424 -- be used when generating attributes of the string, for example
10425 -- in the context of a slice assignment.
10450 ------------------------------
10451 -- Simplify_Type_Conversion --
10452 ------------------------------
10455 begin
10457 declare
10462 begin
10464 and then
10471 -- Special processing required if the conversion is the expression
10472 -- of a Truncation attribute reference. In this case we replace:
10474 -- ityp (ftyp'Truncation (x))
10476 -- by
10478 -- ityp (x)
10480 -- with the Float_Truncate flag set, which is more efficient.
10482 then
10491 -----------------------------
10492 -- Unique_Fixed_Point_Type --
10493 -----------------------------
10502 -- Give error messages for true ambiguity. Messages are posted on node
10503 -- N, and entities T1, T2 are the possible interpretations.
10505 -----------------------
10506 -- Fixed_Point_Error --
10507 -----------------------
10510 begin
10516 -- Start of processing for Unique_Fixed_Point_Type
10518 begin
10519 -- The operations on Duration are visible, so Duration is always a
10520 -- possible interpretation.
10524 -- Look for fixed-point types in enclosing scopes
10533 then
10535 Fixed_Point_Error;
10537 else
10548 -- Look for visible fixed type declarations in the context
10559 then
10561 Fixed_Point_Error;
10563 else
10576 Error_Msg_NE
10578 else
10579 Error_Msg_NE
10586 ----------------------
10587 -- Valid_Conversion --
10588 ----------------------
10590 function Valid_Conversion
10595 is
10600 function Conversion_Check
10603 -- Little routine to post Msg if Valid is False, returns Valid value
10606 -- If Report_Errs, then calls Errout.Error_Msg_N with its arguments
10608 procedure Conversion_Error_NE
10612 -- If Report_Errs, then calls Errout.Error_Msg_NE with its arguments
10614 function Valid_Tagged_Conversion
10617 -- Specifically test for validity of tagged conversions
10620 -- Check index and component conformance, and accessibility levels if
10621 -- the component types are anonymous access types (Ada 2005).
10623 ----------------------
10624 -- Conversion_Check --
10625 ----------------------
10627 function Conversion_Check
10630 is
10631 begin
10632 if not Valid
10634 -- A generic unit has already been analyzed and we have verified
10635 -- that a particular conversion is OK in that context. Since the
10636 -- instance is reanalyzed without relying on the relationships
10637 -- established during the analysis of the generic, it is possible
10638 -- to end up with inconsistent views of private types. Do not emit
10639 -- the error message in such cases. The rest of the machinery in
10640 -- Valid_Conversion still ensures the proper compatibility of
10641 -- target and operand types.
10643 and then not In_Instance
10644 then
10651 ------------------------
10652 -- Conversion_Error_N --
10653 ------------------------
10656 begin
10662 -------------------------
10663 -- Conversion_Error_NE --
10664 -------------------------
10666 procedure Conversion_Error_NE
10670 is
10671 begin
10677 ----------------------------
10678 -- Valid_Array_Conversion --
10679 ----------------------------
10682 is
10697 begin
10698 -- Error if wrong number of dimensions
10700 if
10702 then
10703 Conversion_Error_N
10707 -- Number of dimensions matches
10709 else
10710 -- Loop through indexes of the two arrays
10718 -- Error if index types are incompatible
10724 then
10725 Conversion_Error_N
10727 Operand);
10735 -- If component types have same base type, all set
10740 -- Here if base types of components are not the same. The only
10741 -- time this is allowed is if we have anonymous access types.
10743 -- The conversion of arrays of anonymous access types can lead
10744 -- to dangling pointers. AI-392 formalizes the accessibility
10745 -- checks that must be applied to such conversions to prevent
10746 -- out-of-scope references.
10748 elsif Ekind_In
10750 E_Anonymous_Access_Subprogram_Type)
10752 and then
10754 then
10757 then
10759 Conversion_Error_N
10762 Conversion_Error_N
10764 Operand);
10771 -- Conversion not allowed because of accessibility levels
10773 else
10774 Conversion_Error_N
10780 else
10784 -- All other cases where component base types do not match
10786 else
10787 Conversion_Error_N
10789 Operand);
10793 -- Check that component subtypes statically match. For numeric
10794 -- types this means that both must be either constrained or
10795 -- unconstrained. For enumeration types the bounds must match.
10796 -- All of this is checked in Subtypes_Statically_Match.
10798 if not Subtypes_Statically_Match
10800 then
10801 Conversion_Error_N
10810 -----------------------------
10811 -- Valid_Tagged_Conversion --
10812 -----------------------------
10814 function Valid_Tagged_Conversion
10817 is
10818 begin
10819 -- Upward conversions are allowed (RM 4.6(22))
10823 then
10826 -- Downward conversion are allowed if the operand is class-wide
10827 -- (RM 4.6(23)).
10831 then
10836 then
10837 return
10841 -- Ada 2005 (AI-251): The conversion to/from interface types is
10842 -- always valid
10847 -- If the operand is a class-wide type obtained through a limited_
10848 -- with clause, and the context includes the non-limited view, use
10849 -- it to determine whether the conversion is legal.
10855 then
10860 then
10863 else
10864 Conversion_Error_NE
10871 -- Start of processing for Valid_Conversion
10873 begin
10877 declare
10885 begin
10886 -- Remove procedure calls, which syntactically cannot appear in
10887 -- this context, but which cannot be removed by type checking,
10888 -- because the context does not impose a type.
10890 -- When compiling for VMS, spurious ambiguities can be produced
10891 -- when arithmetic operations have a literal operand and return
10892 -- System.Address or a descendant of it. These ambiguities are
10893 -- otherwise resolved by the context, but for conversions there
10894 -- is no context type and the removal of the spurious operations
10895 -- must be done explicitly here.
10897 -- The node may be labelled overloaded, but still contain only one
10898 -- interpretation because others were discarded earlier. If this
10899 -- is the case, retain the single interpretation if legal.
10907 then
10908 -- More than one candidate interpretation is available
10918 then
10943 Conversion_Error_N
10946 -- If the interpretation involves a standard operator, use
10947 -- the location of the type, which may be user-defined.
10951 else
10955 Conversion_Error_N -- CODEFIX
10960 else
10964 Conversion_Error_N -- CODEFIX
10976 -- If we are within a child unit, check whether the type of the
10977 -- expression has an ancestor in a parent unit, in which case it
10978 -- belongs to its derivation class even if the ancestor is private.
10979 -- See RM 7.3.1 (5.2/3).
10983 -- Numeric types
10987 -- A universal fixed expression can be converted to any numeric type
10992 -- Also no need to check when in an instance or inlined body, because
10993 -- the legality has been established when the template was analyzed.
10994 -- Furthermore, numeric conversions may occur where only a private
10995 -- view of the operand type is visible at the instantiation point.
10996 -- This results in a spurious error if we check that the operand type
10997 -- is a numeric type.
10999 -- Note: in a previous version of this unit, the following tests were
11000 -- applied only for generated code (Comes_From_Source set to False),
11001 -- but in fact the test is required for source code as well, since
11002 -- this situation can arise in source code.
11007 -- Otherwise we need the conversion check
11009 else
11010 return Conversion_Check
11012 or else
11018 -- Array types
11024 then
11025 Conversion_Error_N
11029 else
11033 -- Ada 2005 (AI-251): Anonymous access types where target references an
11034 -- interface type.
11037 E_Anonymous_Access_Type)
11039 then
11040 -- Check the static accessibility rule of 4.6(17). Note that the
11041 -- check is not enforced when within an instance body, since the
11042 -- RM requires such cases to be caught at run time.
11044 -- If the operand is a rewriting of an allocator no check is needed
11045 -- because there are no accessibility issues.
11053 then
11054 -- In an instance, this is a run-time check, but one we know
11055 -- will fail, so generate an appropriate warning. The raise
11056 -- will be generated by Expand_N_Type_Conversion.
11059 Conversion_Error_N
11061 Operand);
11062 Conversion_Error_N
11065 else
11066 Conversion_Error_N
11068 Operand);
11072 -- Special accessibility checks are needed in the case of access
11073 -- discriminants declared for a limited type.
11077 then
11078 -- When the operand is a selected access discriminant the check
11079 -- needs to be made against the level of the object denoted by
11080 -- the prefix of the selected name (Object_Access_Level handles
11081 -- checking the prefix of the operand for this case).
11086 then
11087 -- In an instance, this is a run-time check, but one we know
11088 -- will fail, so generate an appropriate warning. The raise
11089 -- will be generated by Expand_N_Type_Conversion.
11092 Conversion_Error_N
11095 Conversion_Error_N
11097 Operand);
11098 else
11099 Conversion_Error_N
11106 -- The case of a reference to an access discriminant from
11107 -- within a limited type declaration (which will appear as
11108 -- a discriminal) is always illegal because the level of the
11109 -- discriminant is considered to be deeper than any (nameable)
11110 -- access type.
11114 and then
11117 then
11118 Conversion_Error_N
11120 Operand);
11128 -- General and anonymous access types
11131 E_Anonymous_Access_Type)
11132 and then
11133 Conversion_Check
11135 and then not
11137 E_Access_Protected_Subprogram_Type),
11139 then
11142 then
11143 Conversion_Error_N
11148 -- Check the static accessibility rule of 4.6(17). Note that the
11149 -- check is not enforced when within an instance body, since the RM
11150 -- requires such cases to be caught at run time.
11155 N_Object_Declaration
11156 then
11157 -- Ada 2012 (AI05-0149): Perform legality checking on implicit
11158 -- conversions from an anonymous access type to a named general
11159 -- access type. Such conversions are not allowed in the case of
11160 -- access parameters and stand-alone objects of an anonymous
11161 -- access type. The implicit conversion case is recognized by
11162 -- testing that Comes_From_Source is False and that it's been
11163 -- rewritten. The Comes_From_Source test isn't sufficient because
11164 -- nodes in inlined calls to predefined library routines can have
11165 -- Comes_From_Source set to False. (Is there a better way to test
11166 -- for implicit conversions???)
11173 then
11176 -- Implicit conversions aren't allowed for objects of an
11177 -- anonymous access type, since such objects have nonstatic
11178 -- levels in Ada 2012.
11181 N_Object_Declaration
11182 then
11183 Conversion_Error_N
11188 -- Implicit conversions aren't allowed for anonymous access
11189 -- parameters. The "not Is_Local_Anonymous_Access_Type" test
11190 -- is done to exclude anonymous access results.
11194 N_Function_Specification,
11195 N_Procedure_Specification)
11196 then
11197 Conversion_Error_N
11202 -- This is a case where there's an enclosing object whose
11203 -- to which the "statically deeper than" relationship does
11204 -- not apply (such as an access discriminant selected from
11205 -- a dereference of an access parameter).
11209 then
11210 Conversion_Error_N
11215 -- In other cases, the level of the operand's type must be
11216 -- statically less deep than that of the target type, else
11217 -- implicit conversion is disallowed (by RM12-8.6(27.1/3)).
11221 then
11222 Conversion_Error_N
11231 then
11232 -- In an instance, this is a run-time check, but one we know
11233 -- will fail, so generate an appropriate warning. The raise
11234 -- will be generated by Expand_N_Type_Conversion.
11237 Conversion_Error_N
11239 Operand);
11240 Conversion_Error_N
11243 else
11244 -- Avoid generation of spurious error message
11247 Conversion_Error_N
11249 Operand);
11255 -- Special accessibility checks are needed in the case of access
11256 -- discriminants declared for a limited type.
11260 then
11261 -- When the operand is a selected access discriminant the check
11262 -- needs to be made against the level of the object denoted by
11263 -- the prefix of the selected name (Object_Access_Level handles
11264 -- checking the prefix of the operand for this case).
11269 then
11270 -- In an instance, this is a run-time check, but one we know
11271 -- will fail, so generate an appropriate warning. The raise
11272 -- will be generated by Expand_N_Type_Conversion.
11275 Conversion_Error_N
11278 Conversion_Error_N
11280 Operand);
11282 else
11283 Conversion_Error_N
11290 -- The case of a reference to an access discriminant from
11291 -- within a limited type declaration (which will appear as
11292 -- a discriminal) is always illegal because the level of the
11293 -- discriminant is considered to be deeper than any (nameable)
11294 -- access type.
11297 and then
11300 then
11301 Conversion_Error_N
11303 Operand);
11309 -- In the presence of limited_with clauses we have to use non-limited
11310 -- views, if available.
11314 -- Helper function to handle limited views
11316 --------------------------
11317 -- Full_Designated_Type --
11318 --------------------------
11323 begin
11324 -- Handle the limited view of a type
11329 then
11331 else
11336 -- Local Declarations
11344 -- Start of processing for Check_Limited
11346 begin
11350 else
11352 Conversion_Error_NE
11357 -- Ada 2005 AI-384: legality rule is symmetric in both
11358 -- designated types. The conversion is legal (with possible
11359 -- constraint check) if either designated type is
11360 -- unconstrained.
11363 or else
11365 and then
11368 then
11369 -- Special case, if Value_Size has been used to make the
11370 -- sizes different, the conversion is not allowed even
11371 -- though the subtypes statically match.
11376 then
11377 Conversion_Error_NE
11380 Conversion_Error_NE
11385 -- Normal case where conversion is allowed
11387 else
11391 else
11392 Error_Msg_NE
11400 -- Access to subprogram types. If the operand is an access parameter,
11401 -- the type has a deeper accessibility that any master, and cannot be
11402 -- assigned. We must make an exception if the conversion is part of an
11403 -- assignment and the target is the return object of an extended return
11404 -- statement, because in that case the accessibility check takes place
11405 -- after the return.
11409 then
11413 and then
11417 then
11418 Conversion_Error_N
11420 Operand);
11421 Conversion_Error_N
11424 Operand);
11426 Error_Msg_NE
11431 -- Check that the designated types are subtype conformant
11437 -- Check the static accessibility rule of 4.6(20)
11441 then
11442 Conversion_Error_N
11444 Operand);
11446 -- Check that if the operand type is declared in a generic body,
11447 -- then the target type must be declared within that same body
11448 -- (enforces last sentence of 4.6(20)).
11451 declare
11457 begin
11464 Conversion_Error_N
11473 -- Remote subprogram access types
11477 then
11478 -- It is valid to convert from one RAS type to another provided
11479 -- that their specification statically match.
11481 Check_Subtype_Conformant
11484 Old_Id =>
11486 Err_Loc =>
11487 N);
11490 -- If it was legal in the generic, it's legal in the instance
11495 -- If both are tagged types, check legality of view conversions
11498 and then
11500 then
11503 -- Types derived from the same root type are convertible
11508 -- In an instance or an inlined body, there may be inconsistent views of
11509 -- the same type, or of types derived from a common root.
11512 and then
11515 then
11518 -- Special check for common access type error case
11522 then
11524 Conversion_Error_NE -- CODEFIX
11528 else
11529 Conversion_Error_NE