| blob | 0917ccecf431842feb7efc7341dc15e8959fe1b1 |
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S E M _ R E S --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2010, 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 ------------------------------------------------------------------------------
81 -----------------------
82 -- Local Subprograms --
83 -----------------------
85 -- Second pass (top-down) type checking and overload resolution procedures
86 -- Typ is the type required by context. These procedures propagate the
87 -- type information recursively to the descendants of N. If the node
88 -- is not overloaded, its Etype is established in the first pass. If
89 -- overloaded, the Resolve routines set the correct type. For arith.
90 -- operators, the Etype is the base type of the context.
92 -- Note that Resolve_Attribute is separated off in Sem_Attr
95 -- Enforce the restrictions on the use of discriminants when constraining
96 -- a component of a discriminated type (record or concurrent type).
99 -- Given a node for an operator associated with type T, check that
100 -- the operator is visible. Operators all of whose operands are
101 -- universal must be checked for visibility during resolution
102 -- because their type is not determinable based on their operands.
104 procedure Check_Fully_Declared_Prefix
107 -- Check that the type of the prefix of a dereference is not incomplete
110 -- Given a call node, N, which is known to occur immediately within the
111 -- subprogram being called, determines whether it is a detectable case of
112 -- an infinite recursion, and if so, outputs appropriate messages. Returns
113 -- True if an infinite recursion is detected, and False otherwise.
116 -- If the type of the object being initialized uses the secondary stack
117 -- directly or indirectly, create a transient scope for the call to the
118 -- init proc. This is because we do not create transient scopes for the
119 -- initialization of individual components within the init proc itself.
120 -- Could be optimized away perhaps?
123 -- N is the node for a logical operator. If the operator is predefined, and
124 -- the root type of the operands is Standard.Boolean, then a check is made
125 -- for restriction No_Direct_Boolean_Operators. This procedure also handles
126 -- the style check for Style_Check_Boolean_And_Or.
129 -- Determine whether E is an access type declared by an access
130 -- declaration, and not an (anonymous) allocator type.
133 -- Utility to check whether the entity for an operator is a predefined
134 -- operator, in which case the expression is left as an operator in the
135 -- tree (else it is rewritten into a call). An instance of an intrinsic
136 -- conversion operation may be given an operator name, but is not treated
137 -- like an operator. Note that an operator that is an imported back-end
138 -- builtin has convention Intrinsic, but is expected to be rewritten into
139 -- a call, so such an operator is not treated as predefined by this
140 -- predicate.
143 -- If a default expression in entry call N depends on the discriminants
144 -- of the task, it must be replaced with a reference to the discriminant
145 -- of the task being called.
147 procedure Resolve_Op_Concat_Arg
152 -- Internal procedure for Resolve_Op_Concat to resolve one operand of
153 -- concatenation operator. The operand is either of the array type or of
154 -- the component type. If the operand is an aggregate, and the component
155 -- type is composite, this is ambiguous if component type has aggregates.
158 -- Does the first part of the work of Resolve_Op_Concat
161 -- Does the "rest" of the work of Resolve_Op_Concat, after the left operand
162 -- has been resolved. See Resolve_Op_Concat for details.
199 function Operator_Kind
202 -- Utility to map the name of an operator into the corresponding Node. Used
203 -- by other node rewriting procedures.
206 -- Resolve actuals of call, and add default expressions for missing ones.
207 -- N is the Node_Id for the subprogram call, and Nam is the entity of the
208 -- called subprogram.
211 -- Called from Resolve_Call, when the prefix denotes an entry or element
212 -- of entry family. Actuals are resolved as for subprograms, and the node
213 -- is rebuilt as an entry call. Also called for protected operations. Typ
214 -- is the context type, which is used when the operation is a protected
215 -- function with no arguments, and the return value is indexed.
218 -- A call to a user-defined intrinsic operator is rewritten as a call
219 -- to the corresponding predefined operator, with suitable conversions.
220 -- Note that this applies only for intrinsic operators that denote
221 -- predefined operators, not operators that are intrinsic imports of
222 -- back-end builtins.
225 -- Ditto, for unary operators (arithmetic ones and "not" on signed
226 -- integer types for VMS).
229 -- If an operator node resolves to a call to a user-defined operator,
230 -- rewrite the node as a function call.
232 procedure Make_Call_Into_Operator
236 -- Inverse transformation: if an operator is given in functional notation,
237 -- then after resolving the node, transform into an operator node, so
238 -- that operands are resolved properly. Recall that predefined operators
239 -- do not have a full signature and special resolution rules apply.
241 procedure Rewrite_Renamed_Operator
245 -- An operator can rename another, e.g. in an instantiation. In that
246 -- case, the proper operator node must be constructed and resolved.
249 -- The String_Literal_Subtype is built for all strings that are not
250 -- operands of a static concatenation operation. If the argument is
251 -- not a N_String_Literal node, then the call has no effect.
254 -- Build subtype of array type, with the range specified by the slice
257 -- Called after N has been resolved and evaluated, but before range checks
258 -- have been applied. Currently simplifies a combination of floating-point
259 -- to integer conversion and Truncation attribute.
262 -- A universal_fixed expression in an universal context is unambiguous
263 -- if there is only one applicable fixed point type. Determining whether
264 -- there is only one requires a search over all visible entities, and
265 -- happens only in very pathological cases (see 6115-006).
267 function Valid_Conversion
271 -- Verify legality rules given in 4.6 (8-23). Target is the target
272 -- type of the conversion, which may be an implicit conversion of
273 -- an actual parameter to an anonymous access type (in which case
274 -- N denotes the actual parameter and N = Operand).
276 -------------------------
277 -- Ambiguous_Character --
278 -------------------------
283 begin
287 -- First the ones in Standard
292 -- Include Wide_Wide_Character in Ada 2005 mode
298 -- Now any other types that match
308 -------------------------
309 -- Analyze_And_Resolve --
310 -------------------------
313 begin
319 begin
324 -- Version withs check(s) suppressed
326 procedure Analyze_And_Resolve
330 is
333 begin
335 declare
337 begin
343 else
344 declare
347 begin
355 and then Scope_Is_Transient
356 then
357 -- This can only happen if a transient scope was created
358 -- for an inner expression, which will be removed upon
359 -- completion of the analysis of an enclosing construct.
360 -- The transient scope must have the suppress status of
361 -- the enclosing environment, not of this Analyze call.
364 Scope_Suppress;
368 procedure Analyze_And_Resolve
371 is
374 begin
376 declare
378 begin
384 else
385 declare
388 begin
396 and then Scope_Is_Transient
397 then
399 Scope_Suppress;
403 ----------------------------
404 -- Check_Discriminant_Use --
405 ----------------------------
413 begin
414 -- Any use in a spec-expression is legal
421 -- Discriminant cannot be used to constrain a scalar type
428 then
433 -- The following check catches the unusual case where
434 -- a discriminant appears within an index constraint
435 -- that is part of a larger expression within a constraint
436 -- on a component, e.g. "C : Int range 1 .. F (new A(1 .. D))".
437 -- For now we only check case of record components, and
438 -- note that a similar check should also apply in the
439 -- case of discriminant constraints below. ???
441 -- Note that the check for N_Subtype_Declaration below is to
442 -- detect the valid use of discriminants in the constraints of a
443 -- subtype declaration when this subtype declaration appears
444 -- inside the scope of a record type (which is syntactically
445 -- illegal, but which may be created as part of derived type
446 -- processing for records). See Sem_Ch3.Build_Derived_Record_Type
447 -- for more info.
451 and then not
453 and then
455 N_Subtype_Declaration)
457 then
458 Error_Msg_N
463 -- Detect a common error:
465 -- type R (D : Positive := 100) is record
466 -- Name : String (1 .. D);
467 -- end record;
469 -- The default value causes an object of type R to be allocated
470 -- with room for Positive'Last characters. The RM does not mandate
471 -- the allocation of the maximum size, but that is what GNAT does
472 -- so we should warn the programmer that there is a problem.
481 -- Return True if type T has a large enough range that
482 -- any array whose index type covered the whole range of
483 -- the type would likely raise Storage_Error.
485 ------------------------
486 -- Large_Storage_Type --
487 ------------------------
490 begin
491 -- The type is considered large if its bounds are known at
492 -- compile time and if it requires at least as many bits as
493 -- a Positive to store the possible values.
497 and then
502 -- Start of processing for Check_Large
504 begin
505 -- Check that the Disc has a large range
511 -- If the enclosing type is limited, we allocate only the
512 -- default value, not the maximum, and there is no need for
513 -- a warning.
519 -- Check that it is the high bound
523 then
527 -- Check the array allows a large range at this bound.
528 -- First find the array
542 -- Next, find the dimension
550 loop
559 -- Now, check the dimension has a large range
565 -- Warn about the danger
567 Error_Msg_N
577 -- Legal case is in index or discriminant constraint
580 N_Discriminant_Association)
581 then
583 Error_Msg_N
588 then
589 Error_Msg_N
595 -- Otherwise, context is an expression. It should not be within
596 -- (i.e. a subexpression of) a constraint for a component.
598 else
602 N_Subtype_Indication,
603 N_Entry_Declaration)
604 loop
610 -- If the discriminant is used in an expression that is a bound
611 -- of a scalar type, an Itype is created and the bounds are attached
612 -- to its range, not to the original subtype indication. Such use
613 -- is of course a double fault.
617 N_Derived_Type_Definition)
620 -- The constraint itself may be given by a subtype indication,
621 -- rather than by a more common discrete range.
624 and then
628 then
629 Error_Msg_N
635 --------------------------------
636 -- Check_For_Visible_Operator --
637 --------------------------------
640 begin
642 Error_Msg_NE -- CODEFIX
644 Error_Msg_N -- CODEFIX
649 ----------------------------------
650 -- Check_Fully_Declared_Prefix --
651 ----------------------------------
653 procedure Check_Fully_Declared_Prefix
656 is
657 begin
658 -- Check that the designated type of the prefix of a dereference is
659 -- not an incomplete type. This cannot be done unconditionally, because
660 -- dereferences of private types are legal in default expressions. This
661 -- case is taken care of in Check_Fully_Declared, called below. There
662 -- are also 2005 cases where it is legal for the prefix to be unfrozen.
664 -- This consideration also applies to similar checks for allocators,
665 -- qualified expressions, and type conversions.
667 -- An additional exception concerns other per-object expressions that
668 -- are not directly related to component declarations, in particular
669 -- representation pragmas for tasks. These will be per-object
670 -- expressions if they depend on discriminants or some global entity.
671 -- If the task has access discriminants, the designated type may be
672 -- incomplete at the point the expression is resolved. This resolution
673 -- takes place within the body of the initialization procedure, where
674 -- the discriminant is replaced by its discriminal.
678 then
681 -- Ada 2005 (AI-326): Tagged incomplete types allowed. The wrong usages
682 -- are handled by Analyze_Access_Attribute, Analyze_Assignment,
683 -- Analyze_Object_Renaming, and Freeze_Entity.
689 E_Incomplete_Type
691 then
693 else
698 ------------------------------
699 -- Check_Infinite_Recursion --
700 ------------------------------
707 -- Check whether list of actuals is identical to list of formals
708 -- of called function (which is also the enclosing scope).
710 ------------------------
711 -- Same_Argument_List --
712 ------------------------
719 begin
722 else
731 then
742 -- Start of processing for Check_Infinite_Recursion
744 begin
745 -- Special case, if this is a procedure call and is a call to the
746 -- current procedure with the same argument list, then this is for
747 -- sure an infinite recursion and we insert a call to raise SE.
751 and then Same_Argument_List
752 then
753 declare
755 begin
759 then
770 -- If not that special case, search up tree, quitting if we reach a
771 -- construct (e.g. a conditional) that tells us that this is not a
772 -- case for an infinite recursion warning.
775 loop
778 -- If no parent, then we were not inside a subprogram, this can for
779 -- example happen when processing certain pragmas in a spec. Just
780 -- return False in this case.
786 -- Done if we get to subprogram body, this is definitely an infinite
787 -- recursion case if we did not find anything to stop us.
791 -- If appearing in conditional, result is false
794 N_And_Then,
795 N_If_Statement,
796 N_Case_Statement)
797 then
802 then
803 -- If the call is the expression of a return statement and the
804 -- actuals are identical to the formals, it's worth a warning.
805 -- However, we skip this if there is an immediately preceding
806 -- raise statement, since the call is never executed.
808 -- Furthermore, this corresponds to a common idiom:
810 -- function F (L : Thing) return Boolean is
811 -- begin
812 -- raise Program_Error;
813 -- return F (L);
814 -- end F;
816 -- for generating a stub function
819 and then Same_Argument_List
820 then
823 -- OK, return statement is in a statement list, look for raise
825 declare
828 begin
829 -- Skip past N_Freeze_Entity nodes generated by expansion
834 loop
838 -- If no raise statement, give warning
841 and then
849 else
860 -------------------------------
861 -- Check_Initialization_Call --
862 -------------------------------
868 -- Check whether the creation of an object of the type will involve
869 -- use of the secondary stack. If T is a record type, this is true
870 -- if the expression for some component uses the secondary stack, e.g.
871 -- through a call to a function that returns an unconstrained value.
872 -- False if T is controlled, because cleanups occur elsewhere.
874 -------------
875 -- Uses_SS --
876 -------------
883 begin
884 -- Normally we want to use the underlying type, but if it's not set
885 -- then continue with T.
902 then
903 -- The expression for a dynamic component may be rewritten
904 -- as a dereference, so retrieve original node.
908 -- Return True if the expression is a call to a function
909 -- (including an attribute function such as Image, or a
910 -- user-defined operator) with a result that requires a
911 -- transient scope.
918 then
931 else
936 -- Start of processing for Check_Initialization_Call
938 begin
939 -- Establish a transient scope if the type needs it
946 ---------------------------------------
947 -- Check_No_Direct_Boolean_Operators --
948 ---------------------------------------
951 begin
954 then
955 -- Restriction only applies to original source code
967 ------------------------------
968 -- Check_Parameterless_Call --
969 ------------------------------
975 -- If the prefix is of an access_to_subprogram type, the node must be
976 -- rewritten as a call. Ditto if the prefix is overloaded and all its
977 -- interpretations are access to subprograms.
979 ---------------------------
980 -- Prefix_Is_Access_Subp --
981 ---------------------------
987 begin
989 return
992 else
997 then
1008 -- Start of processing for Check_Parameterless_Call
1010 begin
1011 -- Defend against junk stuff if errors already detected
1018 then
1025 -- If the context expects a value, and the name is a procedure, this is
1026 -- most likely a missing 'Access. Don't try to resolve the parameterless
1027 -- call, error will be caught when the outer call is analyzed.
1032 and then
1034 N_Function_Call,
1035 N_Procedure_Call_Statement)
1036 then
1040 -- Rewrite as call if overloadable entity that is (or could be, in the
1041 -- overloaded case) a function call. If we know for sure that the entity
1042 -- is an enumeration literal, we do not rewrite it.
1049 -- Rewrite as call if it is an explicit dereference of an expression of
1050 -- a subprogram access type, and the subprogram type is not that of a
1051 -- procedure or entry.
1053 or else
1056 -- Rewrite as call if it is a selected component which is a function,
1057 -- this is the case of a call to a protected function (which may be
1058 -- overloaded with other protected operations).
1060 or else
1063 or else
1065 E_Procedure)
1068 -- If one of the above three conditions is met, rewrite as call.
1069 -- Apply the rewriting only once.
1071 then
1074 then
1077 -- If overloaded, overload set belongs to new copy
1081 -- Change node to parameterless function call (note that the
1082 -- Parameter_Associations associations field is left set to Empty,
1083 -- its normal default value since there are no parameters)
1096 -----------------------------
1097 -- Is_Definite_Access_Type --
1098 -----------------------------
1102 begin
1108 ----------------------
1109 -- Is_Predefined_Op --
1110 ----------------------
1113 begin
1114 -- Predefined operators are intrinsic subprograms
1120 -- A call to a back-end builtin is never a predefined operator
1131 -----------------------------
1132 -- Make_Call_Into_Operator --
1133 -----------------------------
1135 procedure Make_Call_Into_Operator
1139 is
1154 -- If the operand is not universal, and the operator is given by a
1155 -- expanded name, verify that the operand has an interpretation with
1156 -- a type defined in the given scope of the operator.
1159 -- Find a type of the given class in the package Pack that contains
1160 -- the operator.
1162 ---------------------------
1163 -- Operand_Type_In_Scope --
1164 ---------------------------
1171 begin
1175 else
1189 ---------------
1190 -- Type_In_P --
1191 ---------------
1197 -- Verify that node is not part of the type declaration for the
1198 -- candidate type, which would otherwise be invisible.
1200 -------------
1201 -- In_Decl --
1202 -------------
1208 begin
1217 else
1220 loop
1223 else
1232 -- Start of processing for Type_In_P
1234 begin
1235 -- If the context type is declared in the prefix package, this
1236 -- is the desired base type.
1240 then
1243 else
1247 and then not In_Decl
1248 then
1259 -- Start of processing for Make_Call_Into_Operator
1261 begin
1264 -- Binary operator
1274 -- Unary operator
1276 else
1282 -- If the operator is denoted by an expanded name, and the prefix is
1283 -- not Standard, but the operator is a predefined one whose scope is
1284 -- Standard, then this is an implicit_operator, inserted as an
1285 -- interpretation by the procedure of the same name. This procedure
1286 -- overestimates the presence of implicit operators, because it does
1287 -- not examine the type of the operands. Verify now that the operand
1288 -- type appears in the given scope. If right operand is universal,
1289 -- check the other operand. In the case of concatenation, either
1290 -- argument can be the component type, so check the type of the result.
1291 -- If both arguments are literals, look for a type of the right kind
1292 -- defined in the given scope. This elaborate nonsense is brought to
1293 -- you courtesy of b33302a. The type itself must be frozen, so we must
1294 -- find the type of the proper class in the given scope.
1296 -- A final wrinkle is the multiplication operator for fixed point types,
1297 -- which is defined in Standard only, and not in the scope of the
1298 -- fixed_point type itself.
1303 -- If the entity being called is defined in the given package, it is
1304 -- a renaming of a predefined operator, and known to be legal.
1308 then
1311 -- Visibility does not need to be checked in an instance: if the
1312 -- operator was not visible in the generic it has been diagnosed
1313 -- already, else there is an implicit copy of it in the instance.
1321 then
1326 -- Ada 2005, AI-420: Predefined equality on Universal_Access is
1327 -- available.
1332 then
1335 else
1344 and then Is_Binary
1346 then
1352 -- Verify that the scope contains a type that corresponds to
1353 -- the given literal. Optimize the case where Pack is Standard.
1375 else
1384 else
1393 then
1396 -- If the type is defined elsewhere, and the operator is not
1397 -- defined in the given scope (by a renaming declaration, e.g.)
1398 -- then this is an error as well. If an extension of System is
1399 -- present, and the type may be defined there, Pack must be
1400 -- System itself.
1407 then
1410 else
1416 then
1423 Error_Msg_NE
1428 -- Detect a mismatch between the context type and the result type
1429 -- in the named package, which is otherwise not detected if the
1430 -- operands are universal. Check is only needed if source entity is
1431 -- an operator, not a function that renames an operator.
1438 and then not In_Instance
1439 then
1442 or else
1444 then
1445 -- Already checked above
1449 -- Operator may be defined in an extension of System
1453 then
1456 else
1457 -- Could we use Wrong_Type here??? (this would require setting
1458 -- Etype (N) to the actual type found where Typ was expected).
1469 else
1473 -- If this is a call to a function that renames a predefined equality,
1474 -- the renaming declaration provides a type that must be used to
1475 -- resolve the operands. This must be done now because resolution of
1476 -- the equality node will not resolve any remaining ambiguity, and it
1477 -- assumes that the first operand is not overloaded.
1482 then
1490 -- Do rewrite setting Comes_From_Source on the result if the original
1491 -- call came from source. Although it is not strictly the case that the
1492 -- operator as such comes from the source, logically it corresponds
1493 -- exactly to the function call in the source, so it should be marked
1494 -- this way (e.g. to make sure that validity checks work fine).
1496 declare
1498 begin
1503 -- If this is an arithmetic operator and the result type is private,
1504 -- the operands and the result must be wrapped in conversion to
1505 -- expose the underlying numeric type and expand the proper checks,
1506 -- e.g. on division.
1510 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
1511 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
1520 else
1525 -------------------
1526 -- Operator_Kind --
1527 -------------------
1529 function Operator_Kind
1532 is
1535 begin
1571 else
1575 -- Unary operators
1577 else
1586 else
1594 ----------------------------
1595 -- Preanalyze_And_Resolve --
1596 ----------------------------
1601 begin
1605 -- We suppress all checks for this analysis, since the checks will
1606 -- be applied properly, and in the right location, when the default
1607 -- expression is reanalyzed and reexpanded later on.
1611 Expander_Mode_Restore;
1615 -- Version without context type
1620 begin
1627 Expander_Mode_Restore;
1631 ----------------------------------
1632 -- Replace_Actual_Discriminants --
1633 ----------------------------------
1641 -------------------
1642 -- Process_Discr --
1643 -------------------
1648 begin
1654 then
1670 -- Start of processing for Replace_Actual_Discriminants
1672 begin
1686 else
1691 -------------
1692 -- Resolve --
1693 -------------
1709 -- Determine whether a node comes from a predefined library unit or
1710 -- Standard.
1713 -- Try and fix up a literal so that it matches its expected type. New
1714 -- literals are manufactured if necessary to avoid cascaded errors.
1717 -- Additional diagnostics when an ambiguous call has an ambiguous
1718 -- argument (typically a controlling actual).
1721 -- Called when attempt at resolving current expression fails
1723 ------------------------------------
1724 -- Comes_From_Predefined_Lib_Unit --
1725 -------------------------------------
1728 begin
1729 return
1735 --------------------
1736 -- Patch_Up_Value --
1737 --------------------
1740 begin
1743 then
1752 then
1761 then
1766 Char_Literal_Value =>
1773 then
1784 -------------------------------
1785 -- Report_Ambiguous_Argument --
1786 -------------------------------
1793 begin
1797 then
1800 -- Could use comments on what is going on here ???
1808 else
1817 -----------------------
1818 -- Resolution_Failed --
1819 -----------------------
1822 begin
1828 -- The caller will return without calling the expander, so we need
1829 -- to set the analyzed flag. Note that it is fine to set Analyzed
1830 -- to True even if we are in the middle of a shallow analysis,
1831 -- (see the spec of sem for more details) since this is an error
1832 -- situation anyway, and there is no point in repeating the
1833 -- analysis later (indeed it won't work to repeat it later, since
1834 -- we haven't got a clear resolution of which entity is being
1835 -- referenced.)
1841 -- Start of processing for Resolve
1843 begin
1848 -- Access attribute on remote subprogram cannot be used for
1849 -- a non-remote access-to-subprogram type.
1860 then
1861 Error_Msg_N
1867 -- If the context is a Remote_Access_To_Subprogram, access attributes
1868 -- must be resolved with the corresponding fat pointer. There is no need
1869 -- to check for the attribute name since the return type of an
1870 -- attribute is never a remote type.
1876 then
1877 declare
1885 begin
1886 -- Check that Typ is a remote access-to-subprogram type
1890 -- Prefix (N) must statically denote a remote subprogram
1891 -- declared in a package specification.
1908 or else
1910 then
1912 Error_Msg_N
1914 N);
1918 -- If we are generating code for a distributed program.
1919 -- perform semantic checks against the corresponding
1920 -- remote entities.
1925 and then Expander_Active
1927 then
1928 Check_Subtype_Conformant
1930 Old_Id => Designated_Type
1951 then
1956 -- Return if already analyzed
1962 -- Return if type = Any_Type (previous error encountered)
1971 -- If not overloaded, then we know the type, and all that needs doing
1972 -- is to check that this type is compatible with the context.
1978 -- In the overloaded case, we must select the interpretation that
1979 -- is compatible with the context (i.e. the type passed to Resolve)
1981 else
1982 -- Loop through possible interpretations
1987 -- We are only interested in interpretations that are compatible
1988 -- with the expected type, any other interpretations are ignored.
1993 Write_Eol;
1996 else
1997 -- Skip the current interpretation if it is disabled by an
1998 -- abstract operator. This action is performed only when the
1999 -- type against which we are resolving is the same as the
2000 -- type of the interpretation.
2007 then
2011 -- First matching interpretation
2019 -- Matching interpretation that is not the first, maybe an
2020 -- error, but there are some cases where preference rules are
2021 -- used to choose between the two possibilities. These and
2022 -- some more obscure cases are handled in Disambiguate.
2024 else
2025 -- If the current statement is part of a predefined library
2026 -- unit, then all interpretations which come from user level
2027 -- packages should not be considered.
2029 if From_Lib
2031 then
2038 -- Disambiguation has succeeded. Skip the remaining
2039 -- interpretations.
2049 else
2050 -- Before we issue an ambiguity complaint, check for
2051 -- the case of a subprogram call where at least one
2052 -- of the arguments is Any_Type, and if so, suppress
2053 -- the message, since it is a cascaded error.
2056 N_Procedure_Call_Statement)
2057 then
2058 declare
2062 begin
2074 Write_Eol;
2087 then
2092 then
2096 -- Not that special case, so issue message using the
2097 -- flag Ambiguous to control printing of the header
2098 -- message only at the start of an ambiguous set.
2103 then
2104 Error_Msg_N
2107 else
2108 Error_Msg_NE -- CODEFIX
2116 Error_Msg_N
2118 else
2119 Error_Msg_N -- CODEFIX
2123 if Nkind_In
2126 then
2127 Report_Ambiguous_Argument;
2133 -- By default, the error message refers to the candidate
2134 -- interpretation. But if it is a predefined operator, it
2135 -- is implicitly declared at the declaration of the type
2136 -- of the operand. Recover the sloc of that declaration
2137 -- for the error message.
2143 Standard_Standard
2144 then
2149 then
2157 Standard_Standard
2158 then
2163 then
2167 -- If this is an indirect call, use the subprogram_type
2168 -- in the message, to have a meaningful location.
2169 -- Also indicate if this is an inherited operation,
2170 -- created by a type declaration.
2175 then
2177 Error_Msg_Sloc :=
2179 else
2186 then
2187 -- Special-case the message for universal_fixed
2188 -- operators, which are not declared with the type
2189 -- of the operand, but appear forever in Standard.
2193 then
2194 Error_Msg_N
2198 else
2199 Error_Msg_N
2203 elsif
2205 then
2206 Error_Msg_N
2208 else
2209 Error_Msg_N -- CODEFIX
2216 -- We have a matching interpretation, Expr_Type is the type
2217 -- from this interpretation, and Seen is the entity.
2219 -- For an operator, just set the entity name. The type will be
2220 -- set by the specific operator resolution routine.
2235 -- For an explicit dereference, attribute reference, range,
2236 -- short-circuit form (which is not an operator node), or call
2237 -- with a name that is an explicit dereference, there is
2238 -- nothing to be done at this point.
2241 N_Attribute_Reference,
2242 N_And_Then,
2243 N_Indexed_Component,
2244 N_Or_Else,
2245 N_Range,
2246 N_Selected_Component,
2247 N_Slice)
2249 then
2252 -- For procedure or function calls, set the type of the name,
2253 -- and also the entity pointer for the prefix.
2258 then
2265 then
2270 -- For all other cases, just set the type of the Name
2272 else
2280 -- Move to next interpretation
2288 -- At this stage Found indicates whether or not an acceptable
2289 -- interpretation exists. If not, then we have an error, except that if
2290 -- the context is Any_Type as a result of some other error, then we
2291 -- suppress the error report.
2296 -- If type we are looking for is Void, then this is the procedure
2297 -- call case, and the error is simply that what we gave is not a
2298 -- procedure name (we think of procedure calls as expressions with
2299 -- types internally, but the user doesn't think of them this way!)
2303 -- Special case message if function used as a procedure
2308 then
2309 Error_Msg_NE
2313 -- Otherwise give general message (not clear what cases this
2314 -- covers, but no harm in providing for them!)
2316 else
2322 -- Otherwise we do have a subexpression with the wrong type
2324 -- Check for the case of an allocator which uses an access type
2325 -- instead of the designated type. This is a common error and we
2326 -- specialize the message, posting an error on the operand of the
2327 -- allocator, complaining that we expected the designated type of
2328 -- the allocator.
2334 then
2338 -- Check for view mismatch on Null in instances, for which the
2339 -- view-swapping mechanism has no identifier.
2345 then
2350 -- Check for an aggregate. Sometimes we can get bogus aggregates
2351 -- from misuse of parentheses, and we are about to complain about
2352 -- the aggregate without even looking inside it.
2354 -- Instead, if we have an aggregate of type Any_Composite, then
2355 -- analyze and resolve the component fields, and then only issue
2356 -- another message if we get no errors doing this (otherwise
2357 -- assume that the errors in the aggregate caused the problem).
2361 then
2362 -- Disable expansion in any case. If there is a type mismatch
2363 -- it may be fatal to try to expand the aggregate. The flag
2364 -- would otherwise be set to false when the error is posted.
2368 declare
2370 -- Check one aggregate, and set Found to True if we have a
2371 -- definite error in any of its elements
2374 -- Check one element of aggregate and set Found to True if
2375 -- we definitely have an error in the element.
2377 ----------------
2378 -- Check_Aggr --
2379 ----------------
2384 begin
2397 -- If this is a default-initialized component, then
2398 -- there is nothing to check. The box will be
2399 -- replaced by the appropriate call during late
2400 -- expansion.
2411 ----------------
2412 -- Check_Elmt --
2413 ----------------
2416 begin
2417 -- If we have a nested aggregate, go inside it (to
2418 -- attempt a naked analyze-resolve of the aggregate
2419 -- can cause undesirable cascaded errors). Do not
2420 -- resolve expression if it needs a type from context,
2421 -- as for integer * fixed expression.
2426 else
2431 then
2441 begin
2446 -- If an error message was issued already, Found got reset
2447 -- to True, so if it is still False, issue the standard
2448 -- Wrong_Type message.
2453 then
2454 declare
2456 begin
2462 -- Protected operation: retrieve operation name
2465 else
2475 declare
2479 begin
2486 Error_Msg_NE
2492 else
2495 else
2501 Resolution_Failed;
2504 -- Test if we have more than one interpretation for the context
2507 Resolution_Failed;
2510 -- Here we have an acceptable interpretation for the context
2512 else
2513 -- Propagate type information and normalize tree for various
2514 -- predefined operations. If the context only imposes a class of
2515 -- types, rather than a specific type, propagate the actual type
2516 -- downward.
2523 then
2526 -- Any_Fixed is legal in a real context only if a specific
2527 -- fixed point type is imposed. If Norman Cohen can be
2528 -- confused by this, it deserves a separate message.
2532 then
2539 -- A user-defined operator is transformed into a function call at
2540 -- this point, so that further processing knows that operators are
2541 -- really operators (i.e. are predefined operators). User-defined
2542 -- operators that are intrinsic are just renamings of the predefined
2543 -- ones, and need not be turned into calls either, but if they rename
2544 -- a different operator, we must transform the node accordingly.
2545 -- Instantiations of Unchecked_Conversion are intrinsic but are
2546 -- treated as functions, even if given an operator designator.
2551 then
2557 and then
2559 N_Subprogram_Renaming_Declaration
2560 then
2563 -- If the node is rewritten, it will be fully resolved in
2564 -- Rewrite_Renamed_Operator.
2574 when N_Aggregate => Resolve_Aggregate (N, Ctx_Type);
2576 when N_Allocator => Resolve_Allocator (N, Ctx_Type);
2578 when N_Short_Circuit
2579 => Resolve_Short_Circuit (N, Ctx_Type);
2581 when N_Attribute_Reference
2582 => Resolve_Attribute (N, Ctx_Type);
2584 when N_Case_Expression
2585 => Resolve_Case_Expression (N, Ctx_Type);
2587 when N_Character_Literal
2588 => Resolve_Character_Literal (N, Ctx_Type);
2590 when N_Conditional_Expression
2591 => Resolve_Conditional_Expression (N, Ctx_Type);
2593 when N_Expanded_Name
2594 => Resolve_Entity_Name (N, Ctx_Type);
2596 when N_Explicit_Dereference
2597 => Resolve_Explicit_Dereference (N, Ctx_Type);
2599 when N_Expression_With_Actions
2600 => Resolve_Expression_With_Actions (N, Ctx_Type);
2602 when N_Extension_Aggregate
2603 => Resolve_Extension_Aggregate (N, Ctx_Type);
2605 when N_Function_Call
2606 => Resolve_Call (N, Ctx_Type);
2608 when N_Identifier
2609 => Resolve_Entity_Name (N, Ctx_Type);
2611 when N_Indexed_Component
2612 => Resolve_Indexed_Component (N, Ctx_Type);
2614 when N_Integer_Literal
2615 => Resolve_Integer_Literal (N, Ctx_Type);
2617 when N_Membership_Test
2618 => Resolve_Membership_Op (N, Ctx_Type);
2620 when N_Null => Resolve_Null (N, Ctx_Type);
2622 when N_Op_And | N_Op_Or | N_Op_Xor
2623 => Resolve_Logical_Op (N, Ctx_Type);
2625 when N_Op_Eq | N_Op_Ne
2626 => Resolve_Equality_Op (N, Ctx_Type);
2628 when N_Op_Lt | N_Op_Le | N_Op_Gt | N_Op_Ge
2629 => Resolve_Comparison_Op (N, Ctx_Type);
2631 when N_Op_Not => Resolve_Op_Not (N, Ctx_Type);
2633 when N_Op_Add | N_Op_Subtract | N_Op_Multiply |
2634 N_Op_Divide | N_Op_Mod | N_Op_Rem
2636 => Resolve_Arithmetic_Op (N, Ctx_Type);
2638 when N_Op_Concat => Resolve_Op_Concat (N, Ctx_Type);
2640 when N_Op_Expon => Resolve_Op_Expon (N, Ctx_Type);
2642 when N_Op_Plus | N_Op_Minus | N_Op_Abs
2643 => Resolve_Unary_Op (N, Ctx_Type);
2645 when N_Op_Shift => Resolve_Shift (N, Ctx_Type);
2647 when N_Procedure_Call_Statement
2648 => Resolve_Call (N, Ctx_Type);
2650 when N_Operator_Symbol
2651 => Resolve_Operator_Symbol (N, Ctx_Type);
2653 when N_Qualified_Expression
2654 => Resolve_Qualified_Expression (N, Ctx_Type);
2656 when N_Raise_xxx_Error
2657 => Set_Etype (N, Ctx_Type);
2659 when N_Range => Resolve_Range (N, Ctx_Type);
2661 when N_Real_Literal
2662 => Resolve_Real_Literal (N, Ctx_Type);
2664 when N_Reference => Resolve_Reference (N, Ctx_Type);
2666 when N_Selected_Component
2667 => Resolve_Selected_Component (N, Ctx_Type);
2669 when N_Slice => Resolve_Slice (N, Ctx_Type);
2671 when N_String_Literal
2672 => Resolve_String_Literal (N, Ctx_Type);
2674 when N_Subprogram_Info
2675 => Resolve_Subprogram_Info (N, Ctx_Type);
2677 when N_Type_Conversion
2678 => Resolve_Type_Conversion (N, Ctx_Type);
2680 when N_Unchecked_Expression =>
2681 Resolve_Unchecked_Expression (N, Ctx_Type);
2683 when N_Unchecked_Type_Conversion =>
2684 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
2685 end case;
2687 -- If the subexpression was replaced by a non-subexpression, then
2688 -- all we do is to expand it. The only legitimate case we know of
2689 -- is converting procedure call statement to entry call statements,
2690 -- but there may be others, so we are making this test general.
2692 if Nkind (N) not in N_Subexpr then
2693 Debug_A_Exit ("resolving ", N, " (done)");
2694 Expand (N);
2695 return;
2696 end if;
2698 -- The expression is definitely NOT overloaded at this point, so
2699 -- we reset the Is_Overloaded flag to avoid any confusion when
2700 -- reanalyzing the node.
2702 Set_Is_Overloaded (N, False);
2704 -- Freeze expression type, entity if it is a name, and designated
2705 -- type if it is an allocator (RM 13.14(10,11,13)).
2707 -- Now that the resolution of the type of the node is complete,
2708 -- and we did not detect an error, we can expand this node. We
2709 -- skip the expand call if we are in a default expression, see
2710 -- section "Handling of Default Expressions" in Sem spec.
2712 Debug_A_Exit ("resolving ", N, " (done)");
2714 -- We unconditionally freeze the expression, even if we are in
2715 -- default expression mode (the Freeze_Expression routine tests
2716 -- this flag and only freezes static types if it is set).
2718 Freeze_Expression (N);
2720 -- Now we can do the expansion
2722 Expand (N);
2723 end if;
2724 end Resolve;
2726 -------------
2727 -- Resolve --
2728 -------------
2730 -- Version with check(s) suppressed
2732 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
2733 begin
2734 if Suppress = All_Checks then
2735 declare
2736 Svg : constant Suppress_Array := Scope_Suppress;
2737 begin
2738 Scope_Suppress := (others => True);
2739 Resolve (N, Typ);
2740 Scope_Suppress := Svg;
2741 end;
2743 else
2744 declare
2745 Svg : constant Boolean := Scope_Suppress (Suppress);
2746 begin
2747 Scope_Suppress (Suppress) := True;
2748 Resolve (N, Typ);
2749 Scope_Suppress (Suppress) := Svg;
2750 end;
2751 end if;
2752 end Resolve;
2754 -------------
2755 -- Resolve --
2756 -------------
2758 -- Version with implicit type
2760 procedure Resolve (N : Node_Id) is
2761 begin
2762 Resolve (N, Etype (N));
2763 end Resolve;
2765 ---------------------
2766 -- Resolve_Actuals --
2767 ---------------------
2769 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
2770 Loc : constant Source_Ptr := Sloc (N);
2771 A : Node_Id;
2772 F : Entity_Id;
2773 A_Typ : Entity_Id;
2774 F_Typ : Entity_Id;
2775 Prev : Node_Id := Empty;
2776 Orig_A : Node_Id;
2778 procedure Check_Argument_Order;
2779 -- Performs a check for the case where the actuals are all simple
2780 -- identifiers that correspond to the formal names, but in the wrong
2781 -- order, which is considered suspicious and cause for a warning.
2783 procedure Check_Prefixed_Call;
2784 -- If the original node is an overloaded call in prefix notation,
2786 -- Try_Object_Operation has already verified that there is a valid
2787 -- interpretation, but the form of the actual can only be determined
2788 -- once the primitive operation is identified.
2791 -- If the actual is missing in a call, insert in the actuals list
2792 -- an instance of the default expression. The insertion is always
2793 -- a named association.
2796 -- Check whether T1 and T2, or their full views, are derived from a
2797 -- common type. Used to enforce the restrictions on array conversions
2798 -- of AI95-00246.
2801 -- Predicate to determine whether an actual that is a concatenation
2802 -- will be evaluated statically and does not need a transient scope.
2803 -- This must be determined before the actual is resolved and expanded
2804 -- because if needed the transient scope must be introduced earlier.
2806 --------------------------
2807 -- Check_Argument_Order --
2808 --------------------------
2811 begin
2812 -- Nothing to do if no parameters, or original node is neither a
2813 -- function call nor a procedure call statement (happens in the
2814 -- operator-transformed-to-function call case), or the call does
2815 -- not come from source, or this warning is off.
2817 if not Warn_On_Parameter_Order
2818 or else
2820 or else
2822 N_Function_Call)
2823 or else
2825 then
2829 declare
2832 begin
2833 -- Nothing to do if only one parameter
2839 -- Here if at least two arguments
2841 declare
2847 -- Set True if an out of order case is found
2849 begin
2850 -- Collect identifier names of actuals, fail if any actual is
2851 -- not a simple identifier, and record max length of name.
2857 else
2863 -- If we got this far, all actuals are identifiers and the list
2864 -- of their names is stored in the Actuals array.
2869 -- If we ran out of formals, that's odd, probably an error
2870 -- which will be detected elsewhere, but abandon the search.
2876 -- If name matches and is in order OK
2881 else
2882 -- If no match, see if it is elsewhere in list and if so
2883 -- flag potential wrong order if type is compatible.
2887 and then
2889 then
2895 -- No match
2903 -- If Formals left over, also probably an error, skip warning
2909 -- Here we give the warning if something was out of order
2912 Error_Msg_N
2919 -------------------------
2920 -- Check_Prefixed_Call --
2921 -------------------------
2930 begin
2931 -- Check whether the call is a prefixed call, with or without
2932 -- additional actuals.
2935 or else
2941 then
2944 then
2945 -- Introduce dereference on object in prefix
2947 New_A :=
2955 then
2956 -- Introduce an implicit 'Access in prefix
2959 Error_Msg_NE
2975 --------------------
2976 -- Insert_Default --
2977 --------------------
2983 begin
2984 -- Missing argument in call, nothing to insert
2989 else
2990 -- Note that we do a full New_Copy_Tree, so that any associated
2991 -- Itypes are properly copied. This may not be needed any more,
2992 -- but it does no harm as a safety measure! Defaults of a generic
2993 -- formal may be out of bounds of the corresponding actual (see
2994 -- cc1311b) and an additional check may be required.
2996 Actval :=
2997 New_Copy_Tree
3004 then
3010 then
3013 then
3014 -- If default is a real literal, do not introduce a
3015 -- conversion whose effect may depend on the run-time
3016 -- size of universal real.
3020 else
3031 -- Resolve aggregates with their base type, to avoid scope
3032 -- anomalies: the subtype was first built in the subprogram
3033 -- declaration, and the current call may be nested.
3037 else
3041 else
3044 -- See note above concerning aggregates
3048 then
3051 -- Resolve entities with their own type, which may differ
3052 -- from the type of a reference in a generic context (the
3053 -- view swapping mechanism did not anticipate the re-analysis
3054 -- of default values in calls).
3059 else
3064 -- If default is a tag indeterminate function call, propagate
3065 -- tag to obtain proper dispatching.
3069 then
3075 -- If the default expression raises constraint error, then just
3076 -- silently replace it with an N_Raise_Constraint_Error node,
3077 -- since we already gave the warning on the subprogram spec.
3087 Assoc :=
3092 -- Case of insertion is first named actual
3096 then
3103 else
3107 else
3111 -- Case of insertion is not first named actual
3113 else
3114 Set_Next_Named_Actual
3126 -------------------
3127 -- Same_Ancestor --
3128 -------------------
3134 begin
3137 then
3143 then
3150 --------------------------
3151 -- Static_Concatenation --
3152 --------------------------
3155 begin
3162 -- Concatenation is static when both operands are static
3163 -- and the concatenation operator is a predefined one.
3166 and then
3168 and then
3173 declare
3175 begin
3178 and then
3182 else
3188 -- Start of processing for Resolve_Actuals
3190 begin
3191 Check_Argument_Order;
3194 Check_Prefixed_Call;
3203 -- If we have an error in any actual or formal, indicated by a type
3204 -- of Any_Type, then abandon resolution attempt, and set result type
3205 -- to Any_Type.
3209 then
3214 -- Case where actual is present
3216 -- If the actual is an entity, generate a reference to it now. We
3217 -- do this before the actual is resolved, because a formal of some
3218 -- protected subprogram, or a task discriminant, will be rewritten
3219 -- during expansion, and the reference to the source entity may
3220 -- be lost.
3225 then
3231 then
3241 or else
3243 then
3244 -- If style checking mode on, check match of formal name
3252 -- If the formal is Out or In_Out, do not resolve and expand the
3253 -- conversion, because it is subsequently expanded into explicit
3254 -- temporaries and assignments. However, the object of the
3255 -- conversion can be resolved. An exception is the case of tagged
3256 -- type conversion with a class-wide actual. In that case we want
3257 -- the tag check to occur and no temporary will be needed (no
3258 -- representation change can occur) and the parameter is passed by
3259 -- reference, so we go ahead and resolve the type conversion.
3260 -- Another exception is the case of reference to component or
3261 -- subcomponent of a bit-packed array, in which case we want to
3262 -- defer expansion to the point the in and out assignments are
3263 -- performed.
3268 then
3271 then
3274 then
3276 -- In a view conversion, the conversion must be legal in
3277 -- both directions, and thus both component types must be
3278 -- aliased, or neither (4.6 (8)).
3280 -- The additional rule 4.6 (24.9.2) seems unduly
3281 -- restrictive: the privacy requirement should not apply
3282 -- to generic types, and should be checked in an
3283 -- instance. ARG query is in order ???
3285 Error_Msg_N
3289 elsif
3291 then
3294 then
3295 Error_Msg_N
3298 else
3299 declare
3301 Component_Type
3303 begin
3306 and then
3311 then
3312 Error_Msg_N
3326 then
3330 -- If the actual is a function call that returns a limited
3331 -- unconstrained object that needs finalization, create a
3332 -- transient scope for it, so that it can receive the proper
3333 -- finalization list.
3338 and then Expander_Active
3339 and then
3341 then
3344 -- A small optimization: if one of the actuals is a concatenation
3345 -- create a block around a procedure call to recover stack space.
3346 -- This alleviates stack usage when several procedure calls in
3347 -- the same statement list use concatenation. We do not perform
3348 -- this wrapping for code statements, where the argument is a
3349 -- static string, and we want to preserve warnings involving
3350 -- sequences of such statements.
3354 and then Expander_Active
3355 and then
3359 then
3363 else
3367 and then
3370 then
3371 Error_Msg_N
3384 -- (Ada 2005: AI-251): If the actual is an allocator whose
3385 -- directly designated type is a class-wide interface, we build
3386 -- an anonymous access type to use it as the type of the
3387 -- allocator. Later, when the subprogram call is expanded, if
3388 -- the interface has a secondary dispatch table the expander
3389 -- will add a type conversion to force the correct displacement
3390 -- of the pointer.
3393 declare
3399 begin
3402 then
3410 -- Ada 2005, AI-162:If the actual is an allocator, the
3411 -- innermost enclosing statement is the master of the
3412 -- created object. This needs to be done with expansion
3413 -- enabled only, otherwise the transient scope will not
3414 -- be removed in the expansion of the wrapped construct.
3417 and then Expander_Active
3418 then
3424 -- (Ada 2005): The call may be to a primitive operation of
3425 -- a tagged synchronized type, declared outside of the type.
3426 -- In this case the controlling actual must be converted to
3427 -- its corresponding record type, which is the formal type.
3428 -- The actual may be a subtype, either because of a constraint
3429 -- or because it is a generic actual, so use base type to
3430 -- locate concurrent type.
3435 declare
3438 begin
3441 else
3445 -- Tagged synchronized type (case 1): the actual is a
3446 -- concurrent type
3450 then
3452 Unchecked_Convert_To
3456 -- Tagged synchronized type (case 2): the formal is a
3457 -- concurrent type
3460 and then Present
3465 then
3468 -- Common case
3470 else
3479 -- Save actual for subsequent check on order dependence,
3480 -- and indicate whether actual is modifiable. For AI05-0144
3482 -- Save_Actual (A,
3483 -- Ekind (F) /= E_In_Parameter or else Is_Access_Type (F_Typ));
3484 -- Why is this code commented out ???
3486 -- For mode IN, if actual is an entity, and the type of the formal
3487 -- has warnings suppressed, then we reset Never_Set_In_Source for
3488 -- the calling entity. The reason for this is to catch cases like
3489 -- GNAT.Spitbol.Patterns.Vstring_Var where the called subprogram
3490 -- uses trickery to modify an IN parameter.
3497 then
3501 -- Perform error checks for IN and IN OUT parameters
3505 -- Check unset reference. For scalar parameters, it is clearly
3506 -- wrong to pass an uninitialized value as either an IN or
3507 -- IN-OUT parameter. For composites, it is also clearly an
3508 -- error to pass a completely uninitialized value as an IN
3509 -- parameter, but the case of IN OUT is trickier. We prefer
3510 -- not to give a warning here. For example, suppose there is
3511 -- a routine that sets some component of a record to False.
3512 -- It is perfectly reasonable to make this IN-OUT and allow
3513 -- either initialized or uninitialized records to be passed
3514 -- in this case.
3516 -- For partially initialized composite values, we also avoid
3517 -- warnings, since it is quite likely that we are passing a
3518 -- partially initialized value and only the initialized fields
3519 -- will in fact be read in the subprogram.
3524 then
3528 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
3529 -- actual to a nested call, since this is case of reading an
3530 -- out parameter, which is not allowed.
3535 then
3540 -- Case of OUT or IN OUT parameter
3544 -- For an Out parameter, check for useless assignment. Note
3545 -- that we can't set Last_Assignment this early, because we may
3546 -- kill current values in Resolve_Call, and that call would
3547 -- clobber the Last_Assignment field.
3549 -- Note: call Warn_On_Useless_Assignment before doing the check
3550 -- below for Is_OK_Variable_For_Out_Formal so that the setting
3551 -- of Referenced_As_LHS/Referenced_As_Out_Formal properly
3552 -- reflects the last assignment, not this one!
3559 then
3564 -- Validate the form of the actual. Note that the call to
3565 -- Is_OK_Variable_For_Out_Formal generates the required
3566 -- reference in this case.
3572 -- What's the following about???
3576 else
3577 Kill_All_Checks;
3586 -- Apply appropriate range checks for in, out, and in-out
3587 -- parameters. Out and in-out parameters also need a separate
3588 -- check, if there is a type conversion, to make sure the return
3589 -- value meets the constraints of the variable before the
3590 -- conversion.
3592 -- Gigi looks at the check flag and uses the appropriate types.
3593 -- For now since one flag is used there is an optimization which
3594 -- might not be done in the In Out case since Gigi does not do
3595 -- any analysis. More thought required about this ???
3609 then
3615 then
3621 then
3624 else
3628 -- Ada 2005 (AI-231)
3634 then
3635 Apply_Compile_Time_Constraint_Error
3646 Apply_Scalar_Range_Check
3648 else
3649 Apply_Range_Check
3653 else
3659 then
3662 else
3668 -- An actual associated with an access parameter is implicitly
3669 -- converted to the anonymous access type of the formal and must
3670 -- satisfy the legality checks for access conversions.
3674 Error_Msg_N
3679 -- Check bad case of atomic/volatile argument (RM C.6(12))
3683 then
3686 then
3687 Error_Msg_N
3689 N);
3693 then
3694 Error_Msg_N
3696 N);
3700 -- Check that subprograms don't have improper controlling
3701 -- arguments (RM 3.9.2 (9)).
3703 -- A primitive operation may have an access parameter of an
3704 -- incomplete tagged type, but a dispatching call is illegal
3705 -- if the type is still incomplete.
3711 declare
3713 begin
3717 then
3718 Error_Msg_NE
3732 then
3737 then
3739 Error_Msg_NE
3749 and then
3754 -- Disable these checks for call to imported C++ subprograms
3756 and then not
3760 then
3761 Error_Msg_N
3766 then
3768 Error_Msg_NE
3775 -- If it is a named association, treat the selector_name as
3776 -- a proper identifier, and mark the corresponding entity.
3793 -- Case where actual is not present
3795 else
3796 Insert_Default;
3803 -----------------------
3804 -- Resolve_Allocator --
3805 -----------------------
3816 procedure Check_Allocator_Discrim_Accessibility
3819 -- Check that accessibility level associated with an access discriminant
3820 -- initialized in an allocator by the expression Disc_Exp is not deeper
3821 -- than the level of the allocator type Alloc_Typ. An error message is
3822 -- issued if this condition is violated. Specialized checks are done for
3823 -- the cases of a constraint expression which is an access attribute or
3824 -- an access discriminant.
3827 -- If the allocator is an actual in a call, it is allowed to be class-
3828 -- wide when the context is not because it is a controlling actual.
3831 -- Propagate all nested coextensions which are located one nesting
3832 -- level down the tree to the node Root. Example:
3833 --
3834 -- Top_Record
3835 -- Level_1_Coextension
3836 -- Level_2_Coextension
3837 --
3838 -- The algorithm is paired with delay actions done by the Expander. In
3839 -- the above example, assume all coextensions are controlled types.
3840 -- The cycle of analysis, resolution and expansion will yield:
3841 --
3842 -- 1) Analyze Top_Record
3843 -- 2) Analyze Level_1_Coextension
3844 -- 3) Analyze Level_2_Coextension
3845 -- 4) Resolve Level_2_Coextension. The allocator is marked as a
3846 -- coextension.
3847 -- 5) Expand Level_2_Coextension. A temporary variable Temp_1 is
3848 -- generated to capture the allocated object. Temp_1 is attached
3849 -- to the coextension chain of Level_2_Coextension.
3850 -- 6) Resolve Level_1_Coextension. The allocator is marked as a
3851 -- coextension. A forward tree traversal is performed which finds
3852 -- Level_2_Coextension's list and copies its contents into its
3853 -- own list.
3854 -- 7) Expand Level_1_Coextension. A temporary variable Temp_2 is
3855 -- generated to capture the allocated object. Temp_2 is attached
3856 -- to the coextension chain of Level_1_Coextension. Currently, the
3857 -- contents of the list are [Temp_2, Temp_1].
3858 -- 8) Resolve Top_Record. A forward tree traversal is performed which
3859 -- finds Level_1_Coextension's list and copies its contents into
3860 -- its own list.
3861 -- 9) Expand Top_Record. Generate finalization calls for Temp_1 and
3862 -- Temp_2 and attach them to Top_Record's finalization list.
3864 -------------------------------------------
3865 -- Check_Allocator_Discrim_Accessibility --
3866 -------------------------------------------
3868 procedure Check_Allocator_Discrim_Accessibility
3871 is
3872 begin
3875 then
3876 Error_Msg_N
3879 -- When the expression is an Access attribute the level of the prefix
3880 -- object must not be deeper than that of the allocator's type.
3884 = Attribute_Access
3887 then
3888 Error_Msg_N
3890 Disc_Exp);
3892 -- When the expression is an access discriminant the check is against
3893 -- the level of the prefix object.
3899 then
3900 Error_Msg_N
3902 Disc_Exp);
3904 -- All other cases are legal
3906 else
3911 ----------------------------
3912 -- In_Dispatching_Context --
3913 ----------------------------
3917 begin
3923 ----------------------------
3924 -- Propagate_Coextensions --
3925 ----------------------------
3930 -- Copy the contents of list From into list To, preserving the
3931 -- order of elements.
3934 -- Recognize an allocator or a rewritten allocator node and add it
3935 -- along with its nested coextensions to the list of Root.
3937 ---------------
3938 -- Copy_List --
3939 ---------------
3943 begin
3951 -----------------------
3952 -- Process_Allocator --
3953 -----------------------
3958 begin
3959 -- This is a possible rewritten subtype indication allocator. Any
3960 -- nested coextensions will appear as discriminant constraints.
3965 then
3966 declare
3970 begin
3972 Discr_Elmt :=
3982 then
3987 Copy_List
3995 -- There is no need to continue the traversal of this
3996 -- subtree since all the information has already been
3997 -- propagated.
4003 -- Case of either a stand alone allocator or a rewritten allocator
4004 -- with an aggregate.
4006 else
4013 -- Propagate the list of nested coextensions to the Root
4014 -- allocator. This is done through list copy since a single
4015 -- allocator may have multiple coextensions. Do not touch
4016 -- coextensions roots.
4020 then
4025 Copy_List
4030 -- There is no need to continue the traversal of this
4031 -- subtree since all the information has already been
4032 -- propagated.
4038 -- Keep on traversing, looking for the next allocator
4046 -- Start of processing for Propagate_Coextensions
4048 begin
4052 -- Start of processing for Resolve_Allocator
4054 begin
4055 -- Replace general access with specific type
4065 -- For qualified expression, resolve the expression using the
4066 -- given subtype (nothing to do for type mark, subtype indication)
4071 and then not In_Dispatching_Context
4072 then
4073 Error_Msg_N
4080 -- A qualified expression requires an exact match of the type,
4081 -- class-wide matching is not allowed.
4086 then
4090 -- A special accessibility check is needed for allocators that
4091 -- constrain access discriminants. The level of the type of the
4092 -- expression used to constrain an access discriminant cannot be
4093 -- deeper than the type of the allocator (in contrast to access
4094 -- parameters, where the level of the actual can be arbitrary).
4096 -- We can't use Valid_Conversion to perform this check because
4097 -- in general the type of the allocator is unrelated to the type
4098 -- of the access discriminant.
4102 then
4109 then
4112 -- Get the first component expression of the aggregate
4122 else
4126 else
4145 else
4150 else
4159 -- For a subtype mark or subtype indication, freeze the subtype
4161 else
4165 Error_Msg_N
4169 -- A special accessibility check is needed for allocators that
4170 -- constrain access discriminants. The level of the type of the
4171 -- expression used to constrain an access discriminant cannot be
4172 -- deeper than the type of the allocator (in contrast to access
4173 -- parameters, where the level of the actual can be arbitrary).
4174 -- We can't use Valid_Conversion to perform this check because
4175 -- in general the type of the allocator is unrelated to the type
4176 -- of the access discriminant.
4181 then
4191 else
4205 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
4206 -- check that the level of the type of the created object is not deeper
4207 -- than the level of the allocator's access type, since extensions can
4208 -- now occur at deeper levels than their ancestor types. This is a
4209 -- static accessibility level check; a run-time check is also needed in
4210 -- the case of an initialized allocator with a class-wide argument (see
4211 -- Expand_Allocator_Expression).
4215 then
4216 declare
4219 begin
4224 else
4233 E);
4239 -- Do not apply Ada 2005 accessibility checks on a class-wide
4240 -- allocator if the type given in the allocator is a formal
4241 -- type. A run-time check will be performed in the instance.
4251 -- Check for allocation from an empty storage pool
4254 declare
4256 begin
4264 -- If the context is an unchecked conversion, as may happen within
4265 -- an inlined subprogram, the allocator is being resolved with its
4266 -- own anonymous type. In that case, if the target type has a specific
4267 -- storage pool, it must be inherited explicitly by the allocator type.
4271 then
4272 Set_Associated_Storage_Pool
4276 -- An erroneous allocator may be rewritten as a raise Program_Error
4277 -- statement.
4281 -- An anonymous access discriminant is the definition of a
4282 -- coextension.
4286 N_Discriminant_Specification
4287 then
4288 -- Avoid marking an allocator as a dynamic coextension if it is
4289 -- within a static construct.
4295 -- Cleanup for potential static coextensions
4297 else
4302 -- There is no need to propagate any nested coextensions if they
4303 -- are marked as static since they will be rewritten on the spot.
4311 ---------------------------
4312 -- Resolve_Arithmetic_Op --
4313 ---------------------------
4315 -- Used for resolving all arithmetic operators except exponentiation
4326 -- We do the resolution using the base type, because intermediate values
4327 -- in expressions always are of the base type, not a subtype of it.
4330 -- Returns True if N is in a context that expects "any real type"
4333 -- Return True iff given type is Integer or universal real/integer
4336 -- Choose type of integer literal in fixed-point operation to conform
4337 -- to available fixed-point type. T is the type of the other operand,
4338 -- which is needed to determine the expected type of N.
4341 -- Set operand type to T if universal
4343 -------------------------------
4344 -- Expected_Type_Is_Any_Real --
4345 -------------------------------
4348 begin
4349 -- N is the expression after "delta" in a fixed_point_definition;
4350 -- see RM-3.5.9(6):
4353 N_Decimal_Fixed_Point_Definition,
4355 -- N is one of the bounds in a real_range_specification;
4356 -- see RM-3.5.7(5):
4358 N_Real_Range_Specification,
4360 -- N is the expression of a delta_constraint;
4361 -- see RM-J.3(3):
4363 N_Delta_Constraint);
4366 -----------------------------
4367 -- Is_Integer_Or_Universal --
4368 -----------------------------
4375 begin
4381 else
4387 then
4398 ----------------------------
4399 -- Set_Mixed_Mode_Operand --
4400 ----------------------------
4406 begin
4409 -- A universal integer literal is resolved as standard integer
4410 -- except in the case of a fixed-point result, where we leave it
4411 -- as universal (to be handled by Exp_Fixd later on)
4415 else
4423 then
4424 -- A universal real can appear in a fixed-type context. We resolve
4425 -- the literal with that context, even though this might raise an
4426 -- exception prematurely (the other operand may be zero).
4433 then
4434 -- Integer arg in mixed-mode operation. Resolve with universal
4435 -- type, in case preference rule must be applied.
4441 then
4442 -- Not a mixed-mode operation, resolve with context
4448 -- N may itself be a mixed-mode operation, so use context type
4455 then
4456 -- Must be (fixed * fixed) operation, operand must have one
4457 -- compatible interpretation.
4465 then
4466 -- C * F(X) in a fixed context, where C is a real literal or a
4467 -- fixed-point expression. F must have either a fixed type
4468 -- interpretation or an integer interpretation, but not both.
4476 else
4484 else
4492 -- Reanalyze the literal with the fixed type of the context. If
4493 -- context is Universal_Fixed, we are within a conversion, leave
4494 -- the literal as a universal real because there is no usable
4495 -- fixed type, and the target of the conversion plays no role in
4496 -- the resolution.
4498 declare
4502 begin
4505 else
4511 then
4513 else
4521 else
4526 ----------------------
4527 -- Set_Operand_Type --
4528 ----------------------
4531 begin
4534 then
4539 -- Start of processing for Resolve_Arithmetic_Op
4541 begin
4546 then
4550 -- Special-case for mixed-mode universal expressions or fixed point
4551 -- type operation: each argument is resolved separately. The same
4552 -- treatment is required if one of the operands of a fixed point
4553 -- operation is universal real, since in this case we don't do a
4554 -- conversion to a specific fixed-point type (instead the expander
4555 -- takes care of the case).
4560 then
4571 or else
4574 then
4579 -- If context is a fixed type and one operand is integer, the
4580 -- other is resolved with the type of the context.
4585 then
4592 then
4596 else
4601 -- Check the rule in RM05-4.5.5(19.1/2) disallowing universal_fixed
4602 -- multiplying operators from being used when the expected type is
4603 -- also universal_fixed. Note that B_Typ will be Universal_Fixed in
4604 -- some cases where the expected type is actually Any_Real;
4605 -- Expected_Type_Is_Any_Real takes care of that case.
4609 then
4613 N_Unchecked_Type_Conversion)
4614 then
4621 else
4624 and then not
4626 N_Unchecked_Type_Conversion)
4627 then
4628 Error_Msg_N
4633 -- The expected type is "any real type" in contexts like
4634 -- type T is delta <universal_fixed-expression> ...
4635 -- in which case we need to set the type to Universal_Real
4636 -- so that static expression evaluation will work properly.
4640 else
4650 then
4655 -- If no previous errors, this is only possible if one operand
4656 -- is overloaded and the context is universal. Resolve as such.
4661 else
4663 and then
4665 then
4669 -- If the context is Universal_Fixed and the operands are also
4670 -- universal fixed, this is an error, unless there is only one
4671 -- applicable fixed_point type (usually Duration).
4679 else
4684 else
4689 -- If one of the arguments was resolved to a non-universal type.
4690 -- label the result of the operation itself with the same type.
4691 -- Do the same for the universal argument, if any.
4702 -- Set overflow and division checking bit. Much cleverer code needed
4703 -- here eventually and perhaps the Resolve routines should be separated
4704 -- for the various arithmetic operations, since they will need
4705 -- different processing. ???
4712 -- Give warning if explicit division by zero
4716 then
4722 or else
4725 then
4726 -- Specialize the warning message according to the operation
4730 Apply_Compile_Time_Constraint_Error
4735 Apply_Compile_Time_Constraint_Error
4740 Apply_Compile_Time_Constraint_Error
4744 -- Division by zero can only happen with division, rem,
4745 -- and mod operations.
4751 -- Otherwise just set the flag to check at run time
4753 else
4758 -- If Restriction No_Implicit_Conditionals is active, then it is
4759 -- violated if either operand can be negative for mod, or for rem
4760 -- if both operands can be negative.
4764 then
4765 declare
4772 -- Set if corresponding operand might be negative
4774 begin
4775 Determine_Range
4779 Determine_Range
4783 -- Check if we will be generating conditionals. There are two
4784 -- cases where that can happen, first for REM, the only case
4785 -- is largest negative integer mod -1, where the division can
4786 -- overflow, but we still have to give the right result. The
4787 -- front end generates a test for this annoying case. Here we
4788 -- just test if both operands can be negative (that's what the
4789 -- expander does, so we match its logic here).
4791 -- The second case is mod where either operand can be negative.
4792 -- In this case, the back end has to generate additonal tests.
4795 or else
4797 then
4808 ------------------
4809 -- Resolve_Call --
4810 ------------------
4822 function Same_Or_Aliased_Subprograms
4825 -- Returns True if the subprogram entity S is the same as E or else
4826 -- S is an alias of E.
4828 ---------------------------------
4829 -- Same_Or_Aliased_Subprograms --
4830 ---------------------------------
4832 function Same_Or_Aliased_Subprograms
4835 is
4837 begin
4842 -- Start of processing for Resolve_Call
4844 begin
4845 -- The context imposes a unique interpretation with type Typ on a
4846 -- procedure or function call. Find the entity of the subprogram that
4847 -- yields the expected type, and propagate the corresponding formal
4848 -- constraints on the actuals. The caller has established that an
4849 -- interpretation exists, and emitted an error if not unique.
4851 -- First deal with the case of a call to an access-to-subprogram,
4852 -- dereference made explicit in Analyze_Call.
4858 else
4859 -- Find the interpretation whose type (a subprogram type) has a
4860 -- return type that is compatible with the context. Analysis of
4861 -- the node has established that one exists.
4880 -- If the prefix is not an entity, then resolve it
4886 -- For an indirect call, we always invalidate checks, since we do not
4887 -- know whether the subprogram is local or global. Yes we could do
4888 -- better here, e.g. by knowing that there are no local subprograms,
4889 -- but it does not seem worth the effort. Similarly, we kill all
4890 -- knowledge of current constant values.
4892 Kill_Current_Values;
4894 -- If this is a procedure call which is really an entry call, do
4895 -- the conversion of the procedure call to an entry call. Protected
4896 -- operations use the same circuitry because the name in the call
4897 -- can be an arbitrary expression with special resolution rules.
4902 then
4906 -- Kill checks and constant values, as above for indirect case
4907 -- Who knows what happens when another task is activated?
4909 Kill_Current_Values;
4912 -- Normal subprogram call with name established in Resolve
4918 -- Otherwise we must have the case of an overloaded call
4920 else
4923 -- Initialize Nam to prevent warning (we know it will be assigned
4924 -- in the loop below, but the compiler does not know that).
4944 then
4945 -- The prefix is a parameterless function call that returns an access
4946 -- to subprogram. If parameters are present in the current call, add
4947 -- add an explicit dereference. We use the base type here because
4948 -- within an instance these may be subtypes.
4950 -- The dereference is added either in Analyze_Call or here. Should
4951 -- be consolidated ???
4960 -- Check that a call to Current_Task does not occur in an entry body
4963 declare
4966 begin
4968 loop
4971 -- Exclude calls that occur within the default of a formal
4972 -- parameter of the entry, since those are evaluated outside
4973 -- of the body.
4980 then
4982 Error_Msg_NE
4985 Error_Msg_NE
4997 -- Check that a procedure call does not occur in the context of the
4998 -- entry call statement of a conditional or timed entry call. Note that
4999 -- the case of a call to a subprogram renaming of an entry will also be
5000 -- rejected. The test for N not being an N_Entry_Call_Statement is
5001 -- defensive, covering the possibility that the processing of entry
5002 -- calls might reach this point due to later modifications of the code
5003 -- above.
5008 then
5012 -- Ada 2005 (AI-345): If a procedure_call_statement is used
5013 -- for a procedure_or_entry_call, the procedure_name or
5014 -- procedure_prefix of the procedure_call_statement shall denote
5015 -- an entry renamed by a procedure, or (a view of) a primitive
5016 -- subprogram of a limited interface whose first parameter is
5017 -- a controlling parameter.
5022 then
5023 Error_Msg_N
5028 -- Check that this is not a call to a protected procedure or entry from
5029 -- within a protected function.
5035 then
5041 -- Freeze the subprogram name if not in a spec-expression. Note that we
5042 -- freeze procedure calls as well as function calls. Procedure calls are
5043 -- not frozen according to the rules (RM 13.14(14)) because it is
5044 -- impossible to have a procedure call to a non-frozen procedure in pure
5045 -- Ada, but in the code that we generate in the expander, this rule
5046 -- needs extending because we can generate procedure calls that need
5047 -- freezing.
5053 -- For a predefined operator, the type of the result is the type imposed
5054 -- by context, except for a predefined operation on universal fixed.
5055 -- Otherwise The type of the call is the type returned by the subprogram
5056 -- being called.
5063 -- If the subprogram returns an array type, and the context requires the
5064 -- component type of that array type, the node is really an indexing of
5065 -- the parameterless call. Resolve as such. A pathological case occurs
5066 -- when the type of the component is an access to the array type. In
5067 -- this case the call is truly ambiguous.
5070 and then
5075 and then
5078 then
5079 declare
5084 begin
5087 then
5088 Error_Msg_N
5090 else
5096 or else
5098 and then
5100 then
5103 -- Indexed call to a parameterless function
5105 Index_Node :=
5107 Prefix =>
5111 else
5112 -- An Ada 2005 prefixed call to a primitive operation
5113 -- whose first parameter is the prefix. This prefix was
5114 -- prepended to the parameter list, which is actually a
5115 -- list of indices. Remove the prefix in order to build
5116 -- the proper indexed component.
5118 Index_Node :=
5120 Prefix =>
5123 Parameter_Associations =>
5124 New_List
5129 -- Preserve the parenthesis count of the node
5133 -- Since we are correcting a node classification error made
5134 -- by the parser, we call Replace rather than Rewrite.
5148 else
5152 -- In the case where the call is to an overloaded subprogram, Analyze
5153 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
5154 -- such a case Normalize_Actuals needs to be called once more to order
5155 -- the actuals correctly. Otherwise the call will have the ordering
5156 -- given by the last overloaded subprogram whether this is the correct
5157 -- one being called or not.
5164 -- In any case, call is fully resolved now. Reset Overload flag, to
5165 -- prevent subsequent overload resolution if node is analyzed again
5170 -- If we are calling the current subprogram from immediately within its
5171 -- body, then that is the case where we can sometimes detect cases of
5172 -- infinite recursion statically. Do not try this in case restriction
5173 -- No_Recursion is in effect anyway, and do it only for source calls.
5178 -- Issue warning for possible infinite recursion in the absence
5179 -- of the No_Recursion restriction.
5184 then
5185 -- Here we detected and flagged an infinite recursion, so we do
5186 -- not need to test the case below for further warnings. Also if
5187 -- we now have a raise SE node, we are all done.
5193 -- If call is to immediately containing subprogram, then check for
5194 -- the case of a possible run-time detectable infinite recursion.
5196 else
5200 -- Although in general case, recursion is not statically
5201 -- checkable, the case of calling an immediately containing
5202 -- subprogram is easy to catch.
5206 -- If the recursive call is to a parameterless subprogram,
5207 -- then even if we can't statically detect infinite
5208 -- recursion, this is pretty suspicious, and we output a
5209 -- warning. Furthermore, we will try later to detect some
5210 -- cases here at run time by expanding checking code (see
5211 -- Detect_Infinite_Recursion in package Exp_Ch6).
5213 -- If the recursive call is within a handler, do not emit a
5214 -- warning, because this is a common idiom: loop until input
5215 -- is correct, catch illegal input in handler and restart.
5221 then
5222 -- For the case of a procedure call. We give the message
5223 -- only if the call is the first statement in a sequence
5224 -- of statements, or if all previous statements are
5225 -- simple assignments. This is simply a heuristic to
5226 -- decrease false positives, without losing too many good
5227 -- warnings. The idea is that these previous statements
5228 -- may affect global variables the procedure depends on.
5232 then
5233 declare
5235 begin
5247 -- Do not give warning if we are in a conditional context
5249 declare
5251 begin
5257 then
5262 -- Here warning is to be issued
5265 Error_Msg_N
5267 Error_Msg_N
5279 -- Check obsolescent reference to Ada.Characters.Handling subprogram
5283 -- If subprogram name is a predefined operator, it was given in
5284 -- functional notation. Replace call node with operator node, so
5285 -- that actuals can be resolved appropriately.
5293 then
5299 -- Create a transient scope if the resulting type requires it
5301 -- There are several notable exceptions:
5303 -- a) In init procs, the transient scope overhead is not needed, and is
5304 -- even incorrect when the call is a nested initialization call for a
5305 -- component whose expansion may generate adjust calls. However, if the
5306 -- call is some other procedure call within an initialization procedure
5307 -- (for example a call to Create_Task in the init_proc of the task
5308 -- run-time record) a transient scope must be created around this call.
5310 -- b) Enumeration literal pseudo-calls need no transient scope
5312 -- c) Intrinsic subprograms (Unchecked_Conversion and source info
5313 -- functions) do not use the secondary stack even though the return
5314 -- type may be unconstrained.
5316 -- d) Calls to a build-in-place function, since such functions may
5317 -- allocate their result directly in a target object, and cases where
5318 -- the result does get allocated in the secondary stack are checked for
5319 -- within the specialized Exp_Ch6 procedures for expanding those
5320 -- build-in-place calls.
5322 -- e) If the subprogram is marked Inline_Always, then even if it returns
5323 -- an unconstrained type the call does not require use of the secondary
5324 -- stack. However, inlining will only take place if the body to inline
5325 -- is already present. It may not be available if e.g. the subprogram is
5326 -- declared in a child instance.
5328 -- If this is an initialization call for a type whose construction
5329 -- uses the secondary stack, and it is not a nested call to initialize
5330 -- a component, we do need to create a transient scope for it. We
5331 -- check for this by traversing the type in Check_Initialization_Call.
5337 then
5343 then
5346 elsif Expander_Active
5349 and then
5351 or else
5353 then
5356 -- If the call appears within the bounds of a loop, it will
5357 -- be rewritten and reanalyzed, nothing left to do here.
5364 and then not Within_Init_Proc
5365 then
5369 -- A protected function cannot be called within the definition of the
5370 -- enclosing protected type.
5375 then
5376 Error_Msg_NE
5380 -- Propagate interpretation to actuals, and add default expressions
5381 -- where needed.
5386 -- Overloaded literals are rewritten as function calls, for purpose of
5387 -- resolution. After resolution, we can replace the call with the
5388 -- literal itself.
5394 -- Avoid validation, since it is a static function call
5400 -- If the subprogram is not global, then kill all saved values and
5401 -- checks. This is a bit conservative, since in many cases we could do
5402 -- better, but it is not worth the effort. Similarly, we kill constant
5403 -- values. However we do not need to do this for internal entities
5404 -- (unless they are inherited user-defined subprograms), since they
5405 -- are not in the business of molesting local values.
5407 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
5408 -- kill all checks and values for calls to global subprograms. This
5409 -- takes care of the case where an access to a local subprogram is
5410 -- taken, and could be passed directly or indirectly and then called
5411 -- from almost any context.
5413 -- Note: we do not do this step till after resolving the actuals. That
5414 -- way we still take advantage of the current value information while
5415 -- scanning the actuals.
5417 -- We suppress killing values if we are processing the nodes associated
5418 -- with N_Freeze_Entity nodes. Otherwise the declaration of a tagged
5419 -- type kills all the values as part of analyzing the code that
5420 -- initializes the dispatch tables.
5424 or else Suppress_Value_Tracking_On_Call
5429 then
5430 Kill_Current_Values;
5433 -- If we are warning about unread OUT parameters, this is the place to
5434 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
5435 -- after the above call to Kill_Current_Values (since that call clears
5436 -- the Last_Assignment field of all local variables).
5441 then
5442 declare
5446 begin
5456 then
5466 -- If the subprogram is a primitive operation, check whether or not
5467 -- it is a correct dispatching call.
5471 then
5476 and then not In_Instance
5477 then
5481 -- If this is a dispatching call, generate the appropriate reference,
5482 -- for better source navigation in GPS.
5486 then
5489 -- Normal case, not a dispatching call
5491 else
5499 -- Check for violation of restriction No_Specific_Termination_Handlers
5500 -- and warn on a potentially blocking call to Abort_Task.
5503 or else
5505 then
5512 -- Issue an error for a call to an eliminated subprogram. We skip this
5513 -- in a spec expression, e.g. a call in a default parameter value, since
5514 -- we are not really doing a call at this time. That's important because
5515 -- the spec expression may itself belong to an eliminated subprogram.
5521 -- All done, evaluate call and deal with elaboration issues
5528 -----------------------------
5529 -- Resolve_Case_Expression --
5530 -----------------------------
5535 begin
5546 -------------------------------
5547 -- Resolve_Character_Literal --
5548 -------------------------------
5554 begin
5555 -- Verify that the character does belong to the type of the context
5560 -- Wide_Wide_Character literals must always be defined, since the set
5561 -- of wide wide character literals is complete, i.e. if a character
5562 -- literal is accepted by the parser, then it is OK for wide wide
5563 -- character (out of range character literals are rejected).
5568 -- Always accept character literal for type Any_Character, which
5569 -- occurs in error situations and in comparisons of literals, both
5570 -- of which should accept all literals.
5575 -- For Standard.Character or a type derived from it, check that
5576 -- the literal is in range
5583 -- For Standard.Wide_Character or a type derived from it, check
5584 -- that the literal is in range
5591 -- For Standard.Wide_Wide_Character or a type derived from it, we
5592 -- know the literal is in range, since the parser checked!
5597 -- If the entity is already set, this has already been resolved in a
5598 -- generic context, or comes from expansion. Nothing else to do.
5603 -- Otherwise we have a user defined character type, and we can use the
5604 -- standard visibility mechanisms to locate the referenced entity.
5606 else
5619 -- If we fall through, then the literal does not match any of the
5620 -- entries of the enumeration type. This isn't just a constraint
5621 -- error situation, it is an illegality (see RM 4.2).
5623 Error_Msg_NE
5627 ---------------------------
5628 -- Resolve_Comparison_Op --
5629 ---------------------------
5631 -- Context requires a boolean type, and plays no role in resolution.
5632 -- Processing identical to that for equality operators. The result
5633 -- type is the base type, which matters when pathological subtypes of
5634 -- booleans with limited ranges are used.
5641 begin
5642 -- If this is an intrinsic operation which is not predefined, use the
5643 -- types of its declared arguments to resolve the possibly overloaded
5644 -- operands. Otherwise the operands are unambiguous and specify the
5645 -- expected type.
5650 else
5664 T = Any_Character
5665 then
5668 else
5675 else
5687 ------------------------------------
5688 -- Resolve_Conditional_Expression --
5689 ------------------------------------
5696 begin
5700 -- If ELSE expression present, just resolve using the determined type
5705 -- If no ELSE expression is present, root type must be Standard.Boolean
5706 -- and we provide a Standard.True result converted to the appropriate
5707 -- Boolean type (in case it is a derived boolean type).
5710 Else_Expr :=
5715 else
5724 -----------------------------------------
5725 -- Resolve_Discrete_Subtype_Indication --
5726 -----------------------------------------
5728 procedure Resolve_Discrete_Subtype_Indication
5731 is
5735 begin
5743 else
5753 Error_Msg_NE
5756 -- Rewrite the constraint as a range of Typ
5757 -- to allow compilation to proceed further.
5769 else
5773 -- Additionally, we must check that the bounds are compatible
5774 -- with the given subtype, which might be different from the
5775 -- type of the context.
5779 -- ??? If the above check statically detects a Constraint_Error
5780 -- it replaces the offending bound(s) of the range R with a
5781 -- Constraint_Error node. When the itype which uses these bounds
5782 -- is frozen the resulting call to Duplicate_Subexpr generates
5783 -- a new temporary for the bounds.
5785 -- Unfortunately there are other itypes that are also made depend
5786 -- on these bounds, so when Duplicate_Subexpr is called they get
5787 -- a forward reference to the newly created temporaries and Gigi
5788 -- aborts on such forward references. This is probably sign of a
5789 -- more fundamental problem somewhere else in either the order of
5790 -- itype freezing or the way certain itypes are constructed.
5792 -- To get around this problem we call Remove_Side_Effects right
5793 -- away if either bounds of R are a Constraint_Error.
5795 declare
5799 begin
5815 -------------------------
5816 -- Resolve_Entity_Name --
5817 -------------------------
5819 -- Used to resolve identifiers and expanded names
5824 begin
5825 -- If garbage from errors, set to Any_Type and return
5832 -- Replace named numbers by corresponding literals. Note that this is
5833 -- the one case where Resolve_Entity_Name must reset the Etype, since
5834 -- it is currently marked as universal.
5844 -- For enumeration literals, we need to make sure that a proper style
5845 -- check is done, since such literals are overloaded, and thus we did
5846 -- not do a style check during the first phase of analysis.
5852 -- Allow use of subtype only if it is a concurrent type where we are
5853 -- currently inside the body. This will eventually be expanded into a
5854 -- call to Self (for tasks) or _object (for protected objects). Any
5855 -- other use of a subtype is invalid.
5860 then
5862 else
5863 Error_Msg_N
5867 -- Check discriminant use if entity is discriminant in current scope,
5868 -- i.e. discriminant of record or concurrent type currently being
5869 -- analyzed. Uses in corresponding body are unrestricted.
5874 then
5877 -- A parameterless generic function cannot appear in a context that
5878 -- requires resolution.
5889 then
5892 -- In all other cases, just do the possible static evaluation
5894 else
5895 -- A deferred constant that appears in an expression must have a
5896 -- completion, unless it has been removed by in-place expansion of
5897 -- an aggregate.
5903 and then not In_Spec_Expression
5905 then
5909 then
5911 else
5912 Error_Msg_N (
5921 -------------------
5922 -- Resolve_Entry --
5923 -------------------
5935 -- If the bounds of the entry family being called depend on task
5936 -- discriminants, build a new index subtype where a discriminant is
5937 -- replaced with the value of the discriminant of the target task.
5938 -- The target task is the prefix of the entry name in the call.
5940 -----------------------
5941 -- Actual_Index_Type --
5942 -----------------------
5952 -- If the bound is given by a discriminant, replace with a reference
5953 -- to the discriminant of the same name in the target task. If the
5954 -- entry name is the target of a requeue statement and the entry is
5955 -- in the current protected object, the bound to be used is the
5956 -- discriminal of the object (see Apply_Range_Checks for details of
5957 -- the transformation).
5959 -----------------------------
5960 -- Actual_Discriminant_Ref --
5961 -----------------------------
5967 begin
5972 then
5978 then
5979 -- Note: here Bound denotes a discriminant of the corresponding
5980 -- record type tskV, whose discriminal is a formal of the
5981 -- init-proc tskVIP. What we want is the body discriminal,
5982 -- which is associated to the discriminant of the original
5983 -- concurrent type tsk.
5985 return New_Occurrence_Of
5988 else
5989 Ref :=
5999 -- Start of processing for Actual_Index_Type
6001 begin
6004 and then
6006 then
6009 else
6023 -- Start of processing of Resolve_Entry
6025 begin
6026 -- Find name of entry being called, and resolve prefix of name
6027 -- with its own type. The prefix can be overloaded, and the name
6028 -- and signature of the entry must be taken into account.
6032 -- Case of dealing with entry family within the current tasks
6036 else
6042 -- Entry call to an entry (or entry family) in the current task. This
6043 -- is legal even though the task will deadlock. Rewrite as call to
6044 -- current task.
6046 -- This can also be a call to an entry in an enclosing task. If this
6047 -- is a single task, we have to retrieve its name, because the scope
6048 -- of the entry is the task type, not the object. If the enclosing
6049 -- task is a task type, the identity of the task is given by its own
6050 -- self variable.
6052 -- Finally this can be a requeue on an entry of the same task or
6053 -- protected object.
6060 then
6061 -- S is an enclosing task or protected object. The concurrent
6062 -- declaration has been converted into a type declaration, and
6063 -- the object itself has an object declaration that follows
6064 -- the type in the same declarative part.
6076 -- Call to current task. Will be transformed into call to Self
6083 New_N :=
6086 Selector_Name =>
6093 then
6094 -- Use the entry name (which must be unique at this point) to find
6095 -- the prefix that returns the corresponding task type or protected
6096 -- type.
6098 declare
6104 begin
6126 -- Up to this point the expression could have been the actual in a
6127 -- simple entry call, and be given by a named association.
6131 else
6137 ------------------------
6138 -- Resolve_Entry_Call --
6139 ------------------------
6151 begin
6152 -- We kill all checks here, because it does not seem worth the effort to
6153 -- do anything better, an entry call is a big operation.
6155 Kill_All_Checks;
6157 -- Processing of the name is similar for entry calls and protected
6158 -- operation calls. Once the entity is determined, we can complete
6159 -- the resolution of the actuals.
6161 -- The selector may be overloaded, in the case of a protected object
6162 -- with overloaded functions. The type of the context is used for
6163 -- resolution.
6168 then
6169 declare
6173 begin
6192 -- Simple entry call
6200 -- Call to member of entry family
6207 -- We cannot in general check the maximum depth of protected entry
6208 -- calls at compile time. But we can tell that any protected entry
6209 -- call at all violates a specified nesting depth of zero.
6215 -- Use context type to disambiguate a protected function that can be
6216 -- called without actuals and that returns an array type, and where
6217 -- the argument list may be an indexing of the returned value.
6222 and then
6230 then
6231 declare
6234 begin
6235 Index_Node :=
6237 Prefix =>
6242 -- Since we are correcting a node classification error made by
6243 -- the parser, we call Replace rather than Rewrite.
6253 -- The operation name may have been overloaded. Order the actuals
6254 -- according to the formals of the resolved entity, and set the
6255 -- return type to that of the operation.
6270 -- Verify that a procedure call cannot masquerade as an entry
6271 -- call where an entry call is expected.
6276 then
6281 then
6286 then
6291 -- After resolution, entry calls and protected procedure calls are
6292 -- changed into entry calls, for expansion. The structure of the node
6293 -- does not change, so it can safely be done in place. Protected
6294 -- function calls must keep their structure because they are
6295 -- subexpressions.
6299 -- A protected operation that is not a function may modify the
6300 -- corresponding object, and cannot apply to a constant. If this
6301 -- is an internal call, the prefix is the type itself.
6307 then
6308 Error_Msg_N
6310 Entry_Name);
6324 -- Protected functions can return on the secondary stack, in which
6325 -- case we must trigger the transient scope mechanism.
6327 elsif Expander_Active
6329 then
6334 -------------------------
6335 -- Resolve_Equality_Op --
6336 -------------------------
6338 -- Both arguments must have the same type, and the boolean context does
6339 -- not participate in the resolution. The first pass verifies that the
6340 -- interpretation is not ambiguous, and the type of the left argument is
6341 -- correctly set, or is Any_Type in case of ambiguity. If both arguments
6342 -- are strings or aggregates, allocators, or Null, they are ambiguous even
6343 -- though they carry a single (universal) type. Diagnose this case here.
6351 -- In the case of allocators, make a last-ditch attempt to find a single
6352 -- access type with the right designated type. This is semantically
6353 -- dubious, and of no interest to any real code, but c48008a makes it
6354 -- all worthwhile.
6356 -----------------------------
6357 -- Find_Unique_Access_Type --
6358 -----------------------------
6365 begin
6370 else
6382 then
6395 -- Start of processing for Resolve_Equality_Op
6397 begin
6409 then
6412 else
6421 then
6434 -- If the unique type is a class-wide type then it will be expanded
6435 -- into a dispatching call to the predefined primitive. Therefore we
6436 -- check here for potential violation of such restriction.
6442 if Warn_On_Redundant_Constructs
6447 then
6448 Error_Msg_N -- CODEFIX
6457 -- If this is an inequality, it may be the implicit inequality
6458 -- created for a user-defined operation, in which case the corres-
6459 -- ponding equality operation is not intrinsic, and the operation
6460 -- cannot be constant-folded. Else fold.
6465 or else Is_Intrinsic_Subprogram
6467 then
6472 then
6476 -- Ada 2005: If one operand is an anonymous access type, convert the
6477 -- other operand to it, to ensure that the underlying types match in
6478 -- the back-end. Same for access_to_subprogram, and the conversion
6479 -- verifies that the types are subtype conformant.
6481 -- We apply the same conversion in the case one of the operands is a
6482 -- private subtype of the type of the other.
6484 -- Why the Expander_Active test here ???
6486 if Expander_Active
6487 and then
6489 E_Anonymous_Access_Subprogram_Type)
6491 then
6511 ----------------------------------
6512 -- Resolve_Explicit_Dereference --
6513 ----------------------------------
6522 begin
6527 -- Use the context type to select the prefix that has the correct
6528 -- designated type.
6539 else
6540 -- If no interpretation covers the designated type of the prefix,
6541 -- this is the pathological case where not all implementations of
6542 -- the prefix allow the interpretation of the node as a call. Now
6543 -- that the expected type is known, Remove other interpretations
6544 -- from prefix, rewrite it as a call, and resolve again, so that
6545 -- the proper call node is generated.
6556 New_N :=
6558 Name =>
6571 else
6579 -- If the designated type is a packed unconstrained array type, and the
6580 -- explicit dereference is not in the context of an attribute reference,
6581 -- then we must compute and set the actual subtype, since it is needed
6582 -- by Gigi. The reason we exclude the attribute case is that this is
6583 -- handled fine by Gigi, and in fact we use such attributes to build the
6584 -- actual subtype. We also exclude generated code (which builds actual
6585 -- subtypes directly if they are needed).
6592 then
6596 -- Note: No Eval processing is required for an explicit dereference,
6597 -- because such a name can never be static.
6601 -------------------------------------
6602 -- Resolve_Expression_With_Actions --
6603 -------------------------------------
6606 begin
6610 -------------------------------
6611 -- Resolve_Indexed_Component --
6612 -------------------------------
6620 begin
6623 -- Use the context type to select the prefix that yields the correct
6624 -- component type.
6626 declare
6633 begin
6640 and then Covers
6642 then
6651 else
6657 else
6668 else
6675 -- If prefix is access type, dereference to get real array type.
6676 -- Note: we do not apply an access check because the expander always
6677 -- introduces an explicit dereference, and the check will happen there.
6683 -- If name was overloaded, set component type correctly now
6684 -- If a misplaced call to an entry family (which has no index types)
6685 -- return. Error will be diagnosed from calling context.
6689 else
6696 -- The prefix may have resolved to a string literal, in which case its
6697 -- etype has a special representation. This is only possible currently
6698 -- if the prefix is a static concatenation, written in functional
6699 -- notation.
6704 else
6711 else
6720 -- Do not generate the warning on suspicious index if we are analyzing
6721 -- package Ada.Tags; otherwise we will report the warning with the
6722 -- Prims_Ptr field of the dispatch table.
6725 or else not
6727 Ada_Tags)
6728 then
6733 -- If the array type is atomic, and is packed, and we are in a left side
6734 -- context, then this is worth a warning, since we have a situation
6735 -- where the access to the component may cause extra read/writes of
6736 -- the atomic array object, which could be considered unexpected.
6744 then
6752 -----------------------------
6753 -- Resolve_Integer_Literal --
6754 -----------------------------
6757 begin
6762 --------------------------------
6763 -- Resolve_Intrinsic_Operator --
6764 --------------------------------
6773 begin
6774 -- We must preserve the original entity in a generic setting, so that
6775 -- the legality of the operation can be verified in an instance.
6790 -- If the operand type is private, rewrite with suitable conversions on
6791 -- the operands and the result, to expose the proper underlying numeric
6792 -- type.
6799 else
6820 then
6821 -- Add explicit conversion where needed, and save interpretations in
6822 -- case operands are overloaded. If the context is a VMS operation,
6823 -- assert that the conversion is legal (the operands have the proper
6824 -- types to select the VMS intrinsic). Note that in rare cases the
6825 -- VMS operators may be visible, but the default System is being used
6826 -- and Address is a private type.
6837 else
6847 else
6857 else
6862 --------------------------------------
6863 -- Resolve_Intrinsic_Unary_Operator --
6864 --------------------------------------
6866 procedure Resolve_Intrinsic_Unary_Operator
6869 is
6874 begin
6893 else
6898 ------------------------
6899 -- Resolve_Logical_Op --
6900 ------------------------
6905 begin
6908 -- Predefined operations on scalar types yield the base type. On the
6909 -- other hand, logical operations on arrays yield the type of the
6910 -- arguments (and the context).
6914 else
6918 -- OK if this is a VMS-specific intrinsic operation
6923 -- The following test is required because the operands of the operation
6924 -- may be literals, in which case the resulting type appears to be
6925 -- compatible with a signed integer type, when in fact it is compatible
6926 -- only with modular types. If the context itself is universal, the
6927 -- operation is illegal.
6935 Error_Msg_N
6942 then
6957 ---------------------------
6958 -- Resolve_Membership_Op --
6959 ---------------------------
6961 -- The context can only be a boolean type, and does not determine
6962 -- the arguments. Arguments should be unambiguous, but the preference
6963 -- rule for universal types applies.
6973 -- Analysis has determined a unique type for the left operand.
6974 -- Use it to resolve the disjuncts.
6976 ----------------------------
6977 -- Resolve_Set_Membership --
6978 ----------------------------
6983 begin
6989 -- Alternative is an expression, a range
6990 -- or a subtype mark.
6994 then
7002 -- Start of processing for Resolve_Membership_Op
7004 begin
7010 Resolve_Set_Membership;
7014 and then
7018 then
7021 -- Ada 2005 (AI-251): Support the following case:
7023 -- type I is interface;
7024 -- type T is tagged ...
7026 -- function Test (O : I'Class) is
7027 -- begin
7028 -- return O in T'Class.
7029 -- end Test;
7031 -- In this case we have nothing else to do. The membership test will be
7032 -- done at run-time.
7039 then
7042 else
7046 -- If mixed-mode operations are present and operands are all literal,
7047 -- the only interpretation involves Duration, which is probably not
7048 -- the intention of the programmer.
7063 then
7069 else
7077 ------------------
7078 -- Resolve_Null --
7079 ------------------
7084 begin
7085 -- Handle restriction against anonymous null access values This
7086 -- restriction can be turned off using -gnatdj.
7088 -- Ada 2005 (AI-231): Remove restriction
7091 and then not Debug_Flag_J
7094 then
7095 -- In the common case of a call which uses an explicitly null value
7096 -- for an access parameter, give specialized error message.
7099 N_Function_Call)
7100 then
7101 Error_Msg_N
7104 -- Standard message for all other cases (are there any?)
7106 else
7107 Error_Msg_N
7112 -- Ada 2005 (AI-231): Generate the null-excluding check in case of
7113 -- assignment to a null-excluding object
7118 then
7120 Insert_Action
7125 else
7132 -- In a distributed context, null for a remote access to subprogram may
7133 -- need to be replaced with a special record aggregate. In this case,
7134 -- return after having done the transformation.
7139 then
7143 -- The null literal takes its type from the context
7148 -----------------------
7149 -- Resolve_Op_Concat --
7150 -----------------------
7154 -- We wish to avoid deep recursion, because concatenations are often
7155 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
7156 -- operands nonrecursively until we find something that is not a simple
7157 -- concatenation (A in this case). We resolve that, and then walk back
7158 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
7159 -- to do the rest of the work at each level. The Parent pointers allow
7160 -- us to avoid recursion, and thus avoid running out of memory. See also
7161 -- Sem_Ch4.Analyze_Concatenation, where a similar approach is used.
7166 begin
7167 -- The following code is equivalent to:
7169 -- Resolve_Op_Concat_First (NN, Typ);
7170 -- Resolve_Op_Concat_Arg (N, ...);
7171 -- Resolve_Op_Concat_Rest (N, Typ);
7173 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
7174 -- operand is a concatenation.
7176 -- Walk down left operands
7178 loop
7187 -- Now (given the above example) NN is A&B and Op1 is A
7189 -- First resolve Op1 ...
7193 -- ... then walk NN back up until we reach N (where we started), calling
7194 -- Resolve_Op_Concat_Rest along the way.
7196 loop
7203 ---------------------------
7204 -- Resolve_Op_Concat_Arg --
7205 ---------------------------
7207 procedure Resolve_Op_Concat_Arg
7212 is
7215 begin
7217 if Is_Comp
7221 then
7223 else
7230 then
7233 else
7238 else
7242 then
7243 declare
7248 begin
7253 -- Special-case the error message when the overloading is
7254 -- caused by a function that yields an array and can be
7255 -- called without parameters.
7260 Error_Msg_NE
7262 Error_Msg_NE
7266 else
7267 Error_Msg_N
7276 then
7277 Error_Msg_N -- CODEFIX
7295 else
7300 else
7307 -----------------------------
7308 -- Resolve_Op_Concat_First --
7309 -----------------------------
7316 begin
7317 -- The parser folds an enormous sequence of concatenations of string
7318 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
7319 -- in the right operand. If the expression resolves to a predefined "&"
7320 -- operator, all is well. Otherwise, the parser's folding is wrong, so
7321 -- we give an error. See P_Simple_Expression in Par.Ch4.
7326 then
7341 ----------------------------
7342 -- Resolve_Op_Concat_Rest --
7343 ----------------------------
7349 begin
7358 -- If this is not a static concatenation, but the result is a string
7359 -- type (and not an array of strings) ensure that static string operands
7360 -- have their subtypes properly constructed.
7364 then
7370 ----------------------
7371 -- Resolve_Op_Expon --
7372 ----------------------
7377 begin
7378 -- Catch attempts to do fixed-point exponentiation with universal
7379 -- operands, which is a case where the illegality is not caught during
7380 -- normal operator analysis.
7391 then
7398 then
7402 -- We do the resolution using the base type, because intermediate values
7403 -- in expressions always are of the base type, not a subtype of it.
7415 -- Set overflow checking bit. Much cleverer code needed here eventually
7416 -- and perhaps the Resolve routines should be separated for the various
7417 -- arithmetic operations, since they will need different processing. ???
7426 --------------------
7427 -- Resolve_Op_Not --
7428 --------------------
7434 -- This function determines if the parent node is a boolean operator
7435 -- or operation (comparison op, membership test, or short circuit form)
7436 -- and the not in question is the left operand of this operation.
7437 -- Note that if the not is in parens, then false is returned.
7439 -----------------------
7440 -- Parent_Is_Boolean --
7441 -----------------------
7444 begin
7448 else
7450 when N_Op_And |
7451 N_Op_Eq |
7452 N_Op_Ge |
7453 N_Op_Gt |
7454 N_Op_Le |
7455 N_Op_Lt |
7456 N_Op_Ne |
7457 N_Op_Or |
7458 N_Op_Xor |
7459 N_In |
7460 N_Not_In |
7461 N_And_Then |
7462 N_Or_Else =>
7472 -- Start of processing for Resolve_Op_Not
7474 begin
7475 -- Predefined operations on scalar types yield the base type. On the
7476 -- other hand, logical operations on arrays yield the type of the
7477 -- arguments (and the context).
7481 else
7488 -- Straightforward case of incorrect arguments
7495 -- Special case of probable missing parens
7499 Error_Msg_N
7502 else
7503 Error_Msg_N
7510 -- OK resolution of not
7512 else
7513 -- Warn if non-boolean types involved. This is a case like not a < b
7514 -- where a and b are modular, where we will get (not a) < b and most
7515 -- likely not (a < b) was intended.
7517 if Warn_On_Questionable_Missing_Parens
7519 and then Parent_Is_Boolean
7520 then
7524 -- Warn on double negation if checking redundant constructs
7526 if Warn_On_Redundant_Constructs
7531 then
7535 -- Complete resolution and evaluation of NOT
7545 -----------------------------
7546 -- Resolve_Operator_Symbol --
7547 -----------------------------
7549 -- Nothing to be done, all resolved already
7555 begin
7559 ----------------------------------
7560 -- Resolve_Qualified_Expression --
7561 ----------------------------------
7569 begin
7572 -- A qualified expression requires an exact match of the type,
7573 -- class-wide matching is not allowed. However, if the qualifying
7574 -- type is specific and the expression has a class-wide type, it
7575 -- may still be okay, since it can be the result of the expansion
7576 -- of a call to a dispatching function, so we also have to check
7577 -- class-wideness of the type of the expression's original node.
7580 or else
7584 then
7588 -- If the target type is unconstrained, then we reset the type of
7589 -- the result from the type of the expression. For other cases, the
7590 -- actual subtype of the expression is the target type.
7594 then
7601 -------------------
7602 -- Resolve_Range --
7603 -------------------
7609 begin
7617 -- We have to check the bounds for being within the base range as
7618 -- required for a non-static context. Normally this is automatic and
7619 -- done as part of evaluating expressions, but the N_Range node is an
7620 -- exception, since in GNAT we consider this node to be a subexpression,
7621 -- even though in Ada it is not. The circuit in Sem_Eval could check for
7622 -- this, but that would put the test on the main evaluation path for
7623 -- expressions.
7628 -- Check for an ambiguous range over character literals. This will
7629 -- happen with a membership test involving only literals.
7637 -- If bounds are static, constant-fold them, so size computations
7638 -- are identical between front-end and back-end. Do not perform this
7639 -- transformation while analyzing generic units, as type information
7640 -- would then be lost when reanalyzing the constant node in the
7641 -- instance.
7654 --------------------------
7655 -- Resolve_Real_Literal --
7656 --------------------------
7661 begin
7662 -- Special processing for fixed-point literals to make sure that the
7663 -- value is an exact multiple of small where this is required. We
7664 -- skip this for the universal real case, and also for generic types.
7670 then
7671 declare
7678 begin
7679 -- Case of literal is not an exact multiple of the Small
7683 -- For a source program literal for a decimal fixed-point
7684 -- type, this is statically illegal (RM 4.9(36)).
7689 then
7693 -- Generate a warning if literal from source
7696 and then Warn_On_Bad_Fixed_Value
7697 then
7698 Error_Msg_N
7700 N);
7703 -- Replace literal by a value that is the exact representation
7704 -- of a value of the type, i.e. a multiple of the small value,
7705 -- by truncation, since Machine_Rounds is false for all GNAT
7706 -- fixed-point types (RM 4.9(38)).
7716 -- In all cases, set the corresponding integer field
7722 -- Now replace the actual type by the expected type as usual
7728 -----------------------
7729 -- Resolve_Reference --
7730 -----------------------
7735 begin
7736 -- Replace general access with specific type
7744 -- If we are taking the reference of a volatile entity, then treat
7745 -- it as a potential modification of this entity. This is much too
7746 -- conservative, but is necessary because remove side effects can
7747 -- result in transformations of normal assignments into reference
7748 -- sequences that otherwise fail to notice the modification.
7755 --------------------------------
7756 -- Resolve_Selected_Component --
7757 --------------------------------
7772 -- Check whether this is the initialization of a component within an
7773 -- init proc (by assignment or call to another init proc). If true,
7774 -- there is no need for a discriminant check.
7776 --------------------
7777 -- Init_Component --
7778 --------------------
7781 begin
7782 return Inside_Init_Proc
7788 -- Start of processing for Resolve_Selected_Component
7790 begin
7793 -- Use the context type to select the prefix that has a selector
7794 -- of the correct name and type.
7802 else
7808 -- The visible components of a class-wide type are those of
7809 -- the root type.
7819 then
7826 else
7830 Error_Msg_N
7835 else
7838 -- There may be an implicit dereference. Retrieve
7839 -- designated record type.
7843 else
7849 -- Resolution chooses the new interpretation.
7850 -- Find the component with the right name.
7855 loop
7876 else
7877 -- Resolve prefix with its type
7882 -- Generate cross-reference. We needed to wait until full overloading
7883 -- resolution was complete to do this, since otherwise we can't tell if
7884 -- we are an lvalue or not.
7888 else
7892 -- If prefix is an access type, the node will be transformed into an
7893 -- explicit dereference during expansion. The type of the node is the
7894 -- designated type of that of the prefix.
7899 else
7910 and then not Init_Component
7911 then
7919 -- If the prefix is a record conversion, this may be a renamed
7920 -- discriminant whose bounds differ from those of the original
7921 -- one, so we must ensure that a range check is performed.
7926 then
7930 -- Note: No Eval processing is required, because the prefix is of a
7931 -- record type, or protected type, and neither can possibly be static.
7933 -- If the array type is atomic, and is packed, and we are in a left side
7934 -- context, then this is worth a warning, since we have a situation
7935 -- where the access to the component may cause extra read/writes of
7936 -- the atomic array object, which could be considered unexpected.
7944 then
7952 -------------------
7953 -- Resolve_Shift --
7954 -------------------
7961 begin
7962 -- We do the resolution using the base type, because intermediate values
7963 -- in expressions always are of the base type, not a subtype of it.
7976 ---------------------------
7977 -- Resolve_Short_Circuit --
7978 ---------------------------
7985 begin
7986 -- Why are the calls to Check_Order_Dependence commented out ???
7988 -- Check_Order_Dependence; -- For AI05-0144
7990 -- Check_Order_Dependence; -- For AI05-0144
7992 -- Check for issuing warning for always False assert/check, this happens
7993 -- when assertions are turned off, in which case the pragma Assert/Check
7994 -- was transformed into:
7996 -- if False and then <condition> then ...
7998 -- and we detect this pattern
8000 if Warn_On_Assertion_Failure
8007 then
8008 declare
8011 begin
8014 then
8015 -- Don't want to warn if original condition is explicit False
8017 declare
8019 Original_Node
8020 (Expression
8022 begin
8025 then
8027 else
8028 -- Issue warning. We do not want the deletion of the
8029 -- IF/AND-THEN to take this message with it. We achieve
8030 -- this by making sure that the expanded code points to
8031 -- the Sloc of the expression, not the original pragma.
8033 Error_Msg_N
8035 Expression
8040 -- Similar processing for Check pragma
8044 then
8045 -- Don't want to warn if original condition is explicit False
8047 declare
8049 Original_Node
8050 (Expression
8053 begin
8056 then
8058 else
8059 Error_Msg_N
8061 Expression
8069 -- Continue with processing of short circuit
8078 -------------------
8079 -- Resolve_Slice --
8080 -------------------
8088 begin
8091 -- Use the context type to select the prefix that yields the correct
8092 -- array type.
8094 declare
8101 begin
8109 then
8117 else
8122 else
8133 else
8143 -- If the prefix is an access to an unconstrained array, we must use
8144 -- the actual subtype of the object to perform the index checks. The
8145 -- object denoted by the prefix is implicit in the node, so we build
8146 -- an explicit representation for it in order to compute the actual
8147 -- subtype.
8152 declare
8156 begin
8167 then
8170 -- If the name is a selected component that depends on discriminants,
8171 -- build an actual subtype for it. This can happen only when the name
8172 -- itself is overloaded; otherwise the actual subtype is created when
8173 -- the selected component is analyzed.
8176 and then Full_Analysis
8178 then
8179 declare
8182 begin
8187 -- Maybe this should just be "else", instead of checking for the
8188 -- specific case of slice??? This is needed for the case where
8189 -- the prefix is an Image attribute, which gets expanded to a
8190 -- slice, and so has a constrained subtype which we want to use
8191 -- for the slice range check applied below (the range check won't
8192 -- get done if the unconstrained subtype of the 'Image is used).
8198 -- If name was overloaded, set slice type correctly now
8202 -- If the range is specified by a subtype mark, no resolution is
8203 -- necessary. Else resolve the bounds, and apply needed checks.
8211 -- Do not apply the range check to nodes associated with the
8212 -- frontend expansion of the dispatch table. We first check
8213 -- if Ada.Tags is already loaded to void the addition of an
8214 -- undesired dependence on such run-time unit.
8216 and then
8218 or else not
8224 then
8239 ----------------------------
8240 -- Resolve_String_Literal --
8241 ----------------------------
8252 begin
8253 -- For a string appearing in a concatenation, defer creation of the
8254 -- string_literal_subtype until the end of the resolution of the
8255 -- concatenation, because the literal may be constant-folded away. This
8256 -- is a useful optimization for long concatenation expressions.
8258 -- If the string is an aggregate built for a single character (which
8259 -- happens in a non-static context) or a is null string to which special
8260 -- checks may apply, we build the subtype. Wide strings must also get a
8261 -- string subtype if they come from a one character aggregate. Strings
8262 -- generated by attributes might be static, but it is often hard to
8263 -- determine whether the enclosing context is static, so we generate
8264 -- subtypes for them as well, thus losing some rarer optimizations ???
8265 -- Same for strings that come from a static conversion.
8267 Need_Check :=
8276 -- If the resolving type is itself a string literal subtype, we can just
8277 -- reuse it, since there is no point in creating another.
8283 and then not Need_Check
8285 N_Attribute_Reference,
8286 N_Qualified_Expression,
8287 N_Type_Conversion)
8288 then
8291 -- Otherwise we must create a string literal subtype. Note that the
8292 -- whole idea of string literal subtypes is simply to avoid the need
8293 -- for building a full fledged array subtype for each literal.
8295 else
8301 or else Need_Check
8302 then
8309 then
8315 -- The validity of a null string has been checked in the call to
8316 -- Eval_String_Literal.
8321 -- Always accept string literal with component type Any_Character, which
8322 -- occurs in error situations and in comparisons of literals, both of
8323 -- which should accept all literals.
8328 -- If the type is bit-packed, then we always transform the string
8329 -- literal into a full fledged aggregate.
8334 -- Deal with cases of Wide_Wide_String, Wide_String, and String
8336 else
8337 -- For Standard.Wide_Wide_String, or any other type whose component
8338 -- type is Standard.Wide_Wide_Character, we know that all the
8339 -- characters in the string must be acceptable, since the parser
8340 -- accepted the characters as valid character literals.
8345 -- For the case of Standard.String, or any other type whose component
8346 -- type is Standard.Character, we must make sure that there are no
8347 -- wide characters in the string, i.e. that it is entirely composed
8348 -- of characters in range of type Character.
8350 -- If the string literal is the result of a static concatenation, the
8351 -- test has already been performed on the components, and need not be
8352 -- repeated.
8356 then
8360 -- If we are out of range, post error. This is one of the
8361 -- very few places that we place the flag in the middle of
8362 -- a token, right under the offending wide character. Not
8363 -- quite clear if this is right wrt wide character encoding
8364 -- sequences, but it's only an error message!
8366 Error_Msg
8373 -- For the case of Standard.Wide_String, or any other type whose
8374 -- component type is Standard.Wide_Character, we must make sure that
8375 -- there are no wide characters in the string, i.e. that it is
8376 -- entirely composed of characters in range of type Wide_Character.
8378 -- If the string literal is the result of a static concatenation,
8379 -- the test has already been performed on the components, and need
8380 -- not be repeated.
8384 then
8388 -- If we are out of range, post error. This is one of the
8389 -- very few places that we place the flag in the middle of
8390 -- a token, right under the offending wide character.
8392 -- This is not quite right, because characters in general
8393 -- will take more than one character position ???
8395 Error_Msg
8402 -- If the root type is not a standard character, then we will convert
8403 -- the string into an aggregate and will let the aggregate code do
8404 -- the checking. Standard Wide_Wide_Character is also OK here.
8406 else
8410 -- See if the component type of the array corresponding to the string
8411 -- has compile time known bounds. If yes we can directly check
8412 -- whether the evaluation of the string will raise constraint error.
8413 -- Otherwise we need to transform the string literal into the
8414 -- corresponding character aggregate and let the aggregate
8415 -- code do the checking.
8419 -- Check for the case of full range, where we are definitely OK
8425 -- Here the range is not the complete base type range, so check
8427 declare
8435 begin
8438 then
8444 then
8445 Apply_Compile_Time_Constraint_Error
8457 -- If we got here we meed to transform the string literal into the
8458 -- equivalent qualified positional array aggregate. This is rather
8459 -- heavy artillery for this situation, but it is hard work to avoid.
8461 declare
8466 begin
8467 -- Build the character literals, we give them source locations that
8468 -- correspond to the string positions, which is a bit tricky given
8469 -- the possible presence of wide character escape sequences.
8483 -- Should we have a call to Skip_Wide here ???
8484 -- ??? else
8485 -- Skip_Wide (P);
8493 Expression =>
8500 -----------------------------
8501 -- Resolve_Subprogram_Info --
8502 -----------------------------
8505 begin
8509 -----------------------------
8510 -- Resolve_Type_Conversion --
8511 -----------------------------
8522 begin
8523 if not Conv_OK
8525 then
8531 -- Mixed-mode operation involving a literal. Context must be a fixed
8532 -- type which is applied to the literal subsequently.
8540 or else
8542 then
8543 -- Return if expression is ambiguous
8548 -- If nothing else, the available fixed type is Duration
8550 else
8554 -- Resolve the real operand with largest available precision
8558 else
8564 -- If the operand is a literal (it could be a non-static and
8565 -- illegal exponentiation) check whether the use of Duration
8566 -- is potentially inaccurate.
8571 then
8572 Error_Msg_N
8575 Rop);
8576 Error_Msg_N
8583 then
8586 else
8595 -- Note: we do the Eval_Type_Conversion call before applying the
8596 -- required checks for a subtype conversion. This is important, since
8597 -- both are prepared under certain circumstances to change the type
8598 -- conversion to a constraint error node, but in the case of
8599 -- Eval_Type_Conversion this may reflect an illegality in the static
8600 -- case, and we would miss the illegality (getting only a warning
8601 -- message), if we applied the type conversion checks first.
8605 -- Even when evaluation is not possible, we may be able to simplify the
8606 -- conversion or its expression. This needs to be done before applying
8607 -- checks, since otherwise the checks may use the original expression
8608 -- and defeat the simplifications. This is specifically the case for
8609 -- elimination of the floating-point Truncation attribute in
8610 -- float-to-int conversions.
8614 -- If after evaluation we still have a type conversion, then we may need
8615 -- to apply checks required for a subtype conversion.
8617 -- Skip these type conversion checks if universal fixed operands
8618 -- operands involved, since range checks are handled separately for
8619 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
8625 then
8629 -- Issue warning for conversion of simple object to its own type. We
8630 -- have to test the original nodes, since they may have been rewritten
8631 -- by various optimizations.
8635 if Warn_On_Redundant_Constructs
8638 and then not In_Instance
8639 then
8643 -- If the node is part of a larger expression, the Target_Type
8644 -- may not be the original type of the node if the context is a
8645 -- condition. Recover original type to see if conversion is needed.
8649 then
8654 and then
8656 or else
8659 then
8660 -- One more check, do not give warning if the analyzed conversion
8661 -- has an expression with non-static bounds, and the bounds of the
8662 -- target are static. This avoids junk warnings in cases where the
8663 -- conversion is necessary to establish staticness, for example in
8664 -- a case statement.
8668 then
8671 -- Here we give the redundant conversion warning
8673 else
8675 Error_Msg_NE -- CODEFIX
8682 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
8683 -- No need to perform any interface conversion if the type of the
8684 -- expression coincides with the target type.
8687 and then Expander_Active
8689 then
8690 declare
8694 begin
8706 -- Conversion from interface type
8710 -- Ada 2005 (AI-217): Handle entities from limited views
8714 Error_Msg_NE -- CODEFIX
8717 Error_Msg_N
8719 N);
8722 and then not
8725 then
8727 Error_Msg_NE -- CODEFIX
8730 Error_Msg_N
8732 N);
8734 else
8738 -- Conversion to interface type
8742 -- Handle subtypes
8748 if not Interface_Present_In_Ancestor
8751 then
8754 -- The static analysis is not enough to know if the
8755 -- interface is implemented or not. Hence we must pass
8756 -- the work to the expander to generate code to evaluate
8757 -- the conversion at run-time.
8761 else
8764 Error_Msg_N
8769 else
8777 ----------------------
8778 -- Resolve_Unary_Op --
8779 ----------------------
8788 begin
8789 -- Deal with intrinsic unary operators
8795 then
8800 -- Deal with universal cases
8803 or else
8805 then
8812 -- Generate warning for expressions like abs (x mod 2)
8814 if Warn_On_Redundant_Constructs
8816 then
8820 Error_Msg_N -- CODEFIX
8825 -- Deal with reference generation
8831 -- Set overflow checking bit. Much cleverer code needed here eventually
8832 -- and perhaps the Resolve routines should be separated for the various
8833 -- arithmetic operations, since they will need different processing ???
8841 -- Generate warning for expressions like -5 mod 3 for integers. No need
8842 -- to worry in the floating-point case, since parens do not affect the
8843 -- result so there is no point in giving in a warning.
8845 declare
8854 begin
8855 if Warn_On_Questionable_Missing_Parens
8859 then
8862 -- We are looking for cases where the right operand is not
8863 -- parenthesized, and is a binary operator, multiply, divide, or
8864 -- mod. These are the cases where the grouping can affect results.
8868 then
8869 -- For mod, we always give the warning, since the value is
8870 -- affected by the parenthesization (e.g. (-5) mod 315 /=
8871 -- -(5 mod 315)). But for the other cases, the only concern is
8872 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
8873 -- overflows, but (-2) * 64 does not). So we try to give the
8874 -- message only when overflow is possible.
8878 then
8883 else
8889 else
8893 -- Note that the test below is deliberately excluding the
8894 -- largest negative number, since that is a potentially
8895 -- troublesome case (e.g. -2 * x, where the result is the
8896 -- largest negative integer has an overflow with 2 * x).
8903 -- For the multiplication case, the only case we have to worry
8904 -- about is when (-a)*b is exactly the largest negative number
8905 -- so that -(a*b) can cause overflow. This can only happen if
8906 -- a is a power of 2, and more generally if any operand is a
8907 -- constant that is not a power of 2, then the parentheses
8908 -- cannot affect whether overflow occurs. We only bother to
8909 -- test the left most operand
8911 -- Loop looking at left operands for one that has known value
8918 -- Operand value of 0 or 1 skips warning
8923 -- Otherwise check power of 2, if power of 2, warn, if
8924 -- anything else, skip warning.
8926 else
8930 else
8939 -- Keep looking at left operands
8944 -- For rem or "/" we can only have a problematic situation
8945 -- if the divisor has a value of minus one or one. Otherwise
8946 -- overflow is impossible (divisor > 1) or we have a case of
8947 -- division by zero in any case.
8952 then
8956 -- If we fall through warning should be issued
8958 Error_Msg_N
8965 ----------------------------------
8966 -- Resolve_Unchecked_Expression --
8967 ----------------------------------
8969 procedure Resolve_Unchecked_Expression
8972 is
8973 begin
8978 ---------------------------------------
8979 -- Resolve_Unchecked_Type_Conversion --
8980 ---------------------------------------
8982 procedure Resolve_Unchecked_Type_Conversion
8985 is
8991 begin
8992 -- Resolve operand using its own type
8999 ------------------------------
9000 -- Rewrite_Operator_As_Call --
9001 ------------------------------
9008 begin
9015 New_N :=
9026 ------------------------------
9027 -- Rewrite_Renamed_Operator --
9028 ------------------------------
9030 procedure Rewrite_Renamed_Operator
9034 is
9039 begin
9040 -- Rewrite the operator node using the real operator, not its renaming.
9041 -- Exclude user-defined intrinsic operations of the same name, which are
9042 -- treated separately and rewritten as calls.
9051 -- Indicate that both the original entity and its renaming are
9052 -- referenced at this point.
9063 -- If the context type is private, add the appropriate conversions
9064 -- so that the operator is applied to the full view. This is done
9065 -- in the routines that resolve intrinsic operators,
9069 then
9071 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
9072 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
9085 -- Operator renames a user-defined operator of the same name. Use
9086 -- the original operator in the node, which is the one that Gigi
9087 -- knows about.
9094 -----------------------
9095 -- Set_Slice_Subtype --
9096 -----------------------
9098 -- Build an implicit subtype declaration to represent the type delivered
9099 -- by the slice. This is an abbreviated version of an array subtype. We
9100 -- define an index subtype for the slice, using either the subtype name
9101 -- or the discrete range of the slice. To be consistent with index usage
9102 -- elsewhere, we create a list header to hold the single index. This list
9103 -- is not otherwise attached to the syntax tree.
9114 begin
9118 else
9119 -- We force the evaluation of a range. This is definitely needed in
9120 -- the renamed case, and seems safer to do unconditionally. Note in
9121 -- any case that since we will create and insert an Itype referring
9122 -- to this range, we must make sure any side effect removal actions
9123 -- are inserted before the Itype definition.
9134 -- Take a new copy of Drange (where bounds have been rewritten to
9135 -- reference side-effect-vree names). Using a separate tree ensures
9136 -- that further expansion (e.g while rewriting a slice assignment
9137 -- into a FOR loop) does not attempt to remove side effects on the
9138 -- bounds again (which would cause the bounds in the index subtype
9139 -- definition to refer to temporaries before they are defined) (the
9140 -- reason is that some names are considered side effect free here
9141 -- for the subtype, but not in the context of a loop iteration
9142 -- scheme).
9162 -- The Etype of the existing Slice node is reset to this slice subtype.
9163 -- Its bounds are obtained from its first index.
9167 -- For packed slice subtypes, freeze immediately (except in the
9168 -- case of being in a "spec expression" where we never freeze
9169 -- when we first see the expression).
9174 -- For all other cases insert an itype reference in the slice's actions
9175 -- so that the itype is frozen at the proper place in the tree (i.e. at
9176 -- the point where actions for the slice are analyzed). Note that this
9177 -- is different from freezing the itype immediately, which might be
9178 -- premature (e.g. if the slice is within a transient scope).
9180 else
9185 --------------------------------
9186 -- Set_String_Literal_Subtype --
9187 --------------------------------
9195 begin
9209 -- The low bound is set from the low bound of the corresponding
9210 -- index type. Note that we do not store the high bound in the
9211 -- string literal subtype, but it can be deduced if necessary
9212 -- from the length and the low bound.
9216 else
9217 Set_String_Literal_Low_Bound
9221 -- Build bona fide subtype for the string, and wrap it in an
9222 -- unchecked conversion, because the backend expects the
9223 -- String_Literal_Subtype to have a static lower bound.
9225 declare
9231 Right_Opnd =>
9239 begin
9240 Index_Subtype :=
9247 -- In the context, the Index_Type may already have a constraint,
9248 -- so use common base type on string subtype. The base type may
9249 -- be used when generating attributes of the string, for example
9250 -- in the context of a slice assignment.
9275 ------------------------------
9276 -- Simplify_Type_Conversion --
9277 ------------------------------
9280 begin
9282 declare
9287 begin
9289 and then
9296 -- Special processing required if the conversion is the expression
9297 -- of a Truncation attribute reference. In this case we replace:
9299 -- ityp (ftyp'Truncation (x))
9301 -- by
9303 -- ityp (x)
9305 -- with the Float_Truncate flag set, which is more efficient
9307 then
9316 -----------------------------
9317 -- Unique_Fixed_Point_Type --
9318 -----------------------------
9327 -- Give error messages for true ambiguity. Messages are posted on node
9328 -- N, and entities T1, T2 are the possible interpretations.
9330 -----------------------
9331 -- Fixed_Point_Error --
9332 -----------------------
9335 begin
9341 -- Start of processing for Unique_Fixed_Point_Type
9343 begin
9344 -- The operations on Duration are visible, so Duration is always a
9345 -- possible interpretation.
9349 -- Look for fixed-point types in enclosing scopes
9358 then
9360 Fixed_Point_Error;
9362 else
9373 -- Look for visible fixed type declarations in the context
9385 then
9387 Fixed_Point_Error;
9389 else
9403 else
9410 ----------------------
9411 -- Valid_Conversion --
9412 ----------------------
9414 function Valid_Conversion
9418 is
9422 function Conversion_Check
9425 -- Little routine to post Msg if Valid is False, returns Valid value
9427 function Valid_Tagged_Conversion
9430 -- Specifically test for validity of tagged conversions
9433 -- Check index and component conformance, and accessibility levels
9434 -- if the component types are anonymous access types (Ada 2005)
9436 ----------------------
9437 -- Conversion_Check --
9438 ----------------------
9440 function Conversion_Check
9443 is
9444 begin
9452 ----------------------------
9453 -- Valid_Array_Conversion --
9454 ----------------------------
9457 is
9472 begin
9473 -- Error if wrong number of dimensions
9475 if
9477 then
9478 Error_Msg_N
9482 -- Number of dimensions matches
9484 else
9485 -- Loop through indexes of the two arrays
9493 -- Error if index types are incompatible
9499 then
9500 Error_Msg_N
9502 Operand);
9510 -- If component types have same base type, all set
9515 -- Here if base types of components are not the same. The only
9516 -- time this is allowed is if we have anonymous access types.
9518 -- The conversion of arrays of anonymous access types can lead
9519 -- to dangling pointers. AI-392 formalizes the accessibility
9520 -- checks that must be applied to such conversions to prevent
9521 -- out-of-scope references.
9523 elsif
9525 E_Anonymous_Access_Subprogram_Type)
9527 and then
9529 then
9532 then
9537 Operand);
9544 -- Conversion not allowed because of accessibility levels
9546 else
9551 else
9555 -- All other cases where component base types do not match
9557 else
9558 Error_Msg_N
9560 Operand);
9564 -- Check that component subtypes statically match. For numeric
9565 -- types this means that both must be either constrained or
9566 -- unconstrained. For enumeration types the bounds must match.
9567 -- All of this is checked in Subtypes_Statically_Match.
9569 if not Subtypes_Statically_Match
9571 then
9572 Error_Msg_N
9581 -----------------------------
9582 -- Valid_Tagged_Conversion --
9583 -----------------------------
9585 function Valid_Tagged_Conversion
9588 is
9589 begin
9590 -- Upward conversions are allowed (RM 4.6(22))
9594 then
9597 -- Downward conversion are allowed if the operand is class-wide
9598 -- (RM 4.6(23)).
9602 then
9607 then
9608 return
9612 -- Ada 2005 (AI-251): The conversion to/from interface types is
9613 -- always valid
9618 -- If the operand is a class-wide type obtained through a limited_
9619 -- with clause, and the context includes the non-limited view, use
9620 -- it to determine whether the conversion is legal.
9626 then
9631 then
9634 else
9635 Error_Msg_NE
9642 -- Start of processing for Valid_Conversion
9644 begin
9648 declare
9656 begin
9657 -- Remove procedure calls, which syntactically cannot appear in
9658 -- this context, but which cannot be removed by type checking,
9659 -- because the context does not impose a type.
9661 -- When compiling for VMS, spurious ambiguities can be produced
9662 -- when arithmetic operations have a literal operand and return
9663 -- System.Address or a descendant of it. These ambiguities are
9664 -- otherwise resolved by the context, but for conversions there
9665 -- is no context type and the removal of the spurious operations
9666 -- must be done explicitly here.
9668 -- The node may be labelled overloaded, but still contain only
9669 -- one interpretation because others were discarded in previous
9670 -- filters. If this is the case, retain the single interpretation
9671 -- if legal.
9679 then
9680 -- More than one candidate interpretation is available
9690 then
9717 -- If the interpretation involves a standard operator, use
9718 -- the location of the type, which may be user-defined.
9722 else
9726 Error_Msg_N -- CODEFIX
9731 else
9735 Error_Msg_N -- CODEFIX
9747 -- Numeric types
9751 -- A universal fixed expression can be converted to any numeric type
9756 -- Also no need to check when in an instance or inlined body, because
9757 -- the legality has been established when the template was analyzed.
9758 -- Furthermore, numeric conversions may occur where only a private
9759 -- view of the operand type is visible at the instantiation point.
9760 -- This results in a spurious error if we check that the operand type
9761 -- is a numeric type.
9763 -- Note: in a previous version of this unit, the following tests were
9764 -- applied only for generated code (Comes_From_Source set to False),
9765 -- but in fact the test is required for source code as well, since
9766 -- this situation can arise in source code.
9771 -- Otherwise we need the conversion check
9773 else
9774 return Conversion_Check
9779 -- Array types
9785 then
9786 Error_Msg_N
9789 else
9793 -- Ada 2005 (AI-251): Anonymous access types where target references an
9794 -- interface type.
9797 E_Anonymous_Access_Type)
9799 then
9800 -- Check the static accessibility rule of 4.6(17). Note that the
9801 -- check is not enforced when within an instance body, since the
9802 -- RM requires such cases to be caught at run time.
9807 then
9808 -- In an instance, this is a run-time check, but one we know
9809 -- will fail, so generate an appropriate warning. The raise
9810 -- will be generated by Expand_N_Type_Conversion.
9813 Error_Msg_N
9815 Operand);
9816 Error_Msg_N
9818 else
9819 Error_Msg_N
9821 Operand);
9825 -- Special accessibility checks are needed in the case of access
9826 -- discriminants declared for a limited type.
9830 then
9831 -- When the operand is a selected access discriminant the check
9832 -- needs to be made against the level of the object denoted by
9833 -- the prefix of the selected name (Object_Access_Level handles
9834 -- checking the prefix of the operand for this case).
9839 then
9840 -- In an instance, this is a run-time check, but one we know
9841 -- will fail, so generate an appropriate warning. The raise
9842 -- will be generated by Expand_N_Type_Conversion.
9845 Error_Msg_N
9848 Error_Msg_N
9850 else
9851 Error_Msg_N
9858 -- The case of a reference to an access discriminant from
9859 -- within a limited type declaration (which will appear as
9860 -- a discriminal) is always illegal because the level of the
9861 -- discriminant is considered to be deeper than any (nameable)
9862 -- access type.
9866 and then
9869 then
9870 Error_Msg_N
9872 Operand);
9880 -- General and anonymous access types
9883 E_Anonymous_Access_Type)
9884 and then
9885 Conversion_Check
9887 and then not
9889 E_Access_Protected_Subprogram_Type),
9891 then
9894 then
9895 Error_Msg_N
9900 -- Check the static accessibility rule of 4.6(17). Note that the
9901 -- check is not enforced when within an instance body, since the RM
9902 -- requires such cases to be caught at run time.
9906 then
9909 then
9910 -- In an instance, this is a run-time check, but one we know
9911 -- will fail, so generate an appropriate warning. The raise
9912 -- will be generated by Expand_N_Type_Conversion.
9915 Error_Msg_N
9917 Operand);
9918 Error_Msg_N
9921 else
9922 -- Avoid generation of spurious error message
9925 Error_Msg_N
9927 Operand);
9933 -- Special accessibility checks are needed in the case of access
9934 -- discriminants declared for a limited type.
9938 then
9939 -- When the operand is a selected access discriminant the check
9940 -- needs to be made against the level of the object denoted by
9941 -- the prefix of the selected name (Object_Access_Level handles
9942 -- checking the prefix of the operand for this case).
9947 then
9948 -- In an instance, this is a run-time check, but one we know
9949 -- will fail, so generate an appropriate warning. The raise
9950 -- will be generated by Expand_N_Type_Conversion.
9953 Error_Msg_N
9956 Error_Msg_N
9958 Operand);
9960 else
9961 Error_Msg_N
9968 -- The case of a reference to an access discriminant from
9969 -- within a limited type declaration (which will appear as
9970 -- a discriminal) is always illegal because the level of the
9971 -- discriminant is considered to be deeper than any (nameable)
9972 -- access type.
9975 and then
9978 then
9979 Error_Msg_N
9981 Operand);
9987 -- In the presence of limited_with clauses we have to use non-limited
9988 -- views, if available.
9992 -- Helper function to handle limited views
9994 --------------------------
9995 -- Full_Designated_Type --
9996 --------------------------
10001 begin
10002 -- Handle the limited view of a type
10007 then
10009 else
10014 -- Local Declarations
10022 -- Start of processing for Check_Limited
10024 begin
10028 else
10030 Error_Msg_NE
10035 -- Ada 2005 AI-384: legality rule is symmetric in both
10036 -- designated types. The conversion is legal (with possible
10037 -- constraint check) if either designated type is
10038 -- unconstrained.
10041 or else
10043 and then
10046 then
10047 -- Special case, if Value_Size has been used to make the
10048 -- sizes different, the conversion is not allowed even
10049 -- though the subtypes statically match.
10054 then
10055 Error_Msg_NE
10058 Error_Msg_NE
10063 -- Normal case where conversion is allowed
10065 else
10069 else
10070 Error_Msg_NE
10078 -- Access to subprogram types. If the operand is an access parameter,
10079 -- the type has a deeper accessibility that any master, and cannot
10080 -- be assigned. We must make an exception if the conversion is part
10081 -- of an assignment and the target is the return object of an extended
10082 -- return statement, because in that case the accessibility check
10083 -- takes place after the return.
10087 then
10091 and then
10095 then
10096 Error_Msg_N
10098 Operand);
10099 Error_Msg_N
10102 Operand);
10104 Error_Msg_NE
10109 -- Check that the designated types are subtype conformant
10115 -- Check the static accessibility rule of 4.6(20)
10119 then
10120 Error_Msg_N
10122 Operand);
10124 -- Check that if the operand type is declared in a generic body,
10125 -- then the target type must be declared within that same body
10126 -- (enforces last sentence of 4.6(20)).
10129 declare
10135 begin
10142 Error_Msg_N
10151 -- Remote subprogram access types
10155 then
10156 -- It is valid to convert from one RAS type to another provided
10157 -- that their specification statically match.
10159 Check_Subtype_Conformant
10162 Old_Id =>
10164 Err_Loc =>
10165 N);
10168 -- If both are tagged types, check legality of view conversions
10172 then
10175 -- Types derived from the same root type are convertible
10180 -- In an instance or an inlined body, there may be inconsistent
10181 -- views of the same type, or of types derived from a common root.
10184 and then
10187 then
10190 -- Special check for common access type error case
10194 then
10196 Error_Msg_NE -- CODEFIX
10200 else