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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S E M _ R E S --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2013, Free Software Foundation, Inc. --
10 -- --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
20 -- --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
23 -- --
24 ------------------------------------------------------------------------------
83 -----------------------
84 -- Local Subprograms --
85 -----------------------
87 -- Second pass (top-down) type checking and overload resolution procedures
88 -- Typ is the type required by context. These procedures propagate the type
89 -- information recursively to the descendants of N. If the node is not
90 -- overloaded, its Etype is established in the first pass. If overloaded,
91 -- the Resolve routines set the correct type. For arith. operators, the
92 -- Etype is the base type of the context.
94 -- Note that Resolve_Attribute is separated off in Sem_Attr
96 function Bad_Unordered_Enumeration_Reference
99 -- Node N contains a potentially dubious reference to type T, either an
100 -- explicit comparison, or an explicit range. This function returns True
101 -- if the type T is an enumeration type for which No pragma Order has been
102 -- given, and the reference N is not in the same extended source unit as
103 -- the declaration of T.
106 -- Enforce the restrictions on the use of discriminants when constraining
107 -- a component of a discriminated type (record or concurrent type).
110 -- Given a node for an operator associated with type T, check that
111 -- the operator is visible. Operators all of whose operands are
112 -- universal must be checked for visibility during resolution
113 -- because their type is not determinable based on their operands.
115 procedure Check_Fully_Declared_Prefix
118 -- Check that the type of the prefix of a dereference is not incomplete
121 -- Given a call node, N, which is known to occur immediately within the
122 -- subprogram being called, determines whether it is a detectable case of
123 -- an infinite recursion, and if so, outputs appropriate messages. Returns
124 -- True if an infinite recursion is detected, and False otherwise.
127 -- If the type of the object being initialized uses the secondary stack
128 -- directly or indirectly, create a transient scope for the call to the
129 -- init proc. This is because we do not create transient scopes for the
130 -- initialization of individual components within the init proc itself.
131 -- Could be optimized away perhaps?
134 -- N is the node for a logical operator. If the operator is predefined, and
135 -- the root type of the operands is Standard.Boolean, then a check is made
136 -- for restriction No_Direct_Boolean_Operators. This procedure also handles
137 -- the style check for Style_Check_Boolean_And_Or.
140 -- Determine whether E is an access type declared by an access declaration,
141 -- and not an (anonymous) allocator type.
144 -- Utility to check whether the entity for an operator is a predefined
145 -- operator, in which case the expression is left as an operator in the
146 -- tree (else it is rewritten into a call). An instance of an intrinsic
147 -- conversion operation may be given an operator name, but is not treated
148 -- like an operator. Note that an operator that is an imported back-end
149 -- builtin has convention Intrinsic, but is expected to be rewritten into
150 -- a call, so such an operator is not treated as predefined by this
151 -- predicate.
154 -- If a default expression in entry call N depends on the discriminants
155 -- of the task, it must be replaced with a reference to the discriminant
156 -- of the task being called.
158 procedure Resolve_Op_Concat_Arg
163 -- Internal procedure for Resolve_Op_Concat to resolve one operand of
164 -- concatenation operator. The operand is either of the array type or of
165 -- the component type. If the operand is an aggregate, and the component
166 -- type is composite, this is ambiguous if component type has aggregates.
169 -- Does the first part of the work of Resolve_Op_Concat
172 -- Does the "rest" of the work of Resolve_Op_Concat, after the left operand
173 -- has been resolved. See Resolve_Op_Concat for details.
210 function Operator_Kind
213 -- Utility to map the name of an operator into the corresponding Node. Used
214 -- by other node rewriting procedures.
217 -- Resolve actuals of call, and add default expressions for missing ones.
218 -- N is the Node_Id for the subprogram call, and Nam is the entity of the
219 -- called subprogram.
222 -- Called from Resolve_Call, when the prefix denotes an entry or element
223 -- of entry family. Actuals are resolved as for subprograms, and the node
224 -- is rebuilt as an entry call. Also called for protected operations. Typ
225 -- is the context type, which is used when the operation is a protected
226 -- function with no arguments, and the return value is indexed.
229 -- A call to a user-defined intrinsic operator is rewritten as a call to
230 -- the corresponding predefined operator, with suitable conversions. Note
231 -- that this applies only for intrinsic operators that denote predefined
232 -- operators, not ones that are intrinsic imports of back-end builtins.
235 -- Ditto, for unary operators (arithmetic ones and "not" on signed
236 -- integer types for VMS).
239 -- If an operator node resolves to a call to a user-defined operator,
240 -- rewrite the node as a function call.
242 procedure Make_Call_Into_Operator
246 -- Inverse transformation: if an operator is given in functional notation,
247 -- then after resolving the node, transform into an operator node, so
248 -- that operands are resolved properly. Recall that predefined operators
249 -- do not have a full signature and special resolution rules apply.
251 procedure Rewrite_Renamed_Operator
255 -- An operator can rename another, e.g. in an instantiation. In that
256 -- case, the proper operator node must be constructed and resolved.
259 -- The String_Literal_Subtype is built for all strings that are not
260 -- operands of a static concatenation operation. If the argument is
261 -- not a N_String_Literal node, then the call has no effect.
264 -- Build subtype of array type, with the range specified by the slice
267 -- Called after N has been resolved and evaluated, but before range checks
268 -- have been applied. Currently simplifies a combination of floating-point
269 -- to integer conversion and Truncation attribute.
272 -- A universal_fixed expression in an universal context is unambiguous if
273 -- there is only one applicable fixed point type. Determining whether there
274 -- is only one requires a search over all visible entities, and happens
275 -- only in very pathological cases (see 6115-006).
277 -------------------------
278 -- Ambiguous_Character --
279 -------------------------
284 begin
288 -- First the ones in Standard
293 -- Include Wide_Wide_Character in Ada 2005 mode
299 -- Now any other types that match
309 -------------------------
310 -- Analyze_And_Resolve --
311 -------------------------
314 begin
320 begin
325 -- Versions with check(s) suppressed
327 procedure Analyze_And_Resolve
331 is
334 begin
336 declare
338 begin
344 else
345 declare
347 begin
355 and then Scope_Is_Transient
356 then
357 -- This can only happen if a transient scope was created for an inner
358 -- expression, which will be removed upon completion of the analysis
359 -- of an enclosing construct. The transient scope must have the
360 -- suppress status of the enclosing environment, not of this Analyze
361 -- call.
364 Scope_Suppress;
368 procedure Analyze_And_Resolve
371 is
374 begin
376 declare
378 begin
384 else
385 declare
387 begin
396 Scope_Suppress;
400 ----------------------------------------
401 -- Bad_Unordered_Enumeration_Reference --
402 ----------------------------------------
404 function Bad_Unordered_Enumeration_Reference
407 is
408 begin
411 and then Warn_On_Unordered_Enumeration_Type
416 ----------------------------
417 -- Check_Discriminant_Use --
418 ----------------------------
426 begin
427 -- Any use in a spec-expression is legal
434 -- Discriminant cannot be used to constrain a scalar type
441 then
446 -- The following check catches the unusual case where a
447 -- discriminant appears within an index constraint that is part of
448 -- a larger expression within a constraint on a component, e.g. "C
449 -- : Int range 1 .. F (new A(1 .. D))". For now we only check case
450 -- of record components, and note that a similar check should also
451 -- apply in the case of discriminant constraints below. ???
453 -- Note that the check for N_Subtype_Declaration below is to
454 -- detect the valid use of discriminants in the constraints of a
455 -- subtype declaration when this subtype declaration appears
456 -- inside the scope of a record type (which is syntactically
457 -- illegal, but which may be created as part of derived type
458 -- processing for records). See Sem_Ch3.Build_Derived_Record_Type
459 -- for more info.
463 and then not
465 and then
467 N_Subtype_Declaration)
469 then
470 Error_Msg_N
475 -- Detect a common error:
477 -- type R (D : Positive := 100) is record
478 -- Name : String (1 .. D);
479 -- end record;
481 -- The default value causes an object of type R to be allocated
482 -- with room for Positive'Last characters. The RM does not mandate
483 -- the allocation of the maximum size, but that is what GNAT does
484 -- so we should warn the programmer that there is a problem.
493 -- Return True if type T has a large enough range that any
494 -- array whose index type covered the whole range of the type
495 -- would likely raise Storage_Error.
497 ------------------------
498 -- Large_Storage_Type --
499 ------------------------
502 begin
503 -- The type is considered large if its bounds are known at
504 -- compile time and if it requires at least as many bits as
505 -- a Positive to store the possible values.
509 and then
514 -- Start of processing for Check_Large
516 begin
517 -- Check that the Disc has a large range
523 -- If the enclosing type is limited, we allocate only the
524 -- default value, not the maximum, and there is no need for
525 -- a warning.
531 -- Check that it is the high bound
535 then
539 -- Check the array allows a large range at this bound. First
540 -- find the array
554 -- Next, find the dimension
562 loop
571 -- Now, check the dimension has a large range
577 -- Warn about the danger
579 Error_Msg_N
589 -- Legal case is in index or discriminant constraint
592 N_Discriminant_Association)
593 then
595 Error_Msg_N
600 then
601 Error_Msg_N
607 -- Otherwise, context is an expression. It should not be within (i.e. a
608 -- subexpression of) a constraint for a component.
610 else
614 N_Subtype_Indication,
615 N_Entry_Declaration)
616 loop
622 -- If the discriminant is used in an expression that is a bound of a
623 -- scalar type, an Itype is created and the bounds are attached to
624 -- its range, not to the original subtype indication. Such use is of
625 -- course a double fault.
629 N_Derived_Type_Definition)
632 -- The constraint itself may be given by a subtype indication,
633 -- rather than by a more common discrete range.
636 and then
640 then
641 Error_Msg_N
647 --------------------------------
648 -- Check_For_Visible_Operator --
649 --------------------------------
652 begin
654 Error_Msg_NE -- CODEFIX
656 Error_Msg_N -- CODEFIX
661 ----------------------------------
662 -- Check_Fully_Declared_Prefix --
663 ----------------------------------
665 procedure Check_Fully_Declared_Prefix
668 is
669 begin
670 -- Check that the designated type of the prefix of a dereference is
671 -- not an incomplete type. This cannot be done unconditionally, because
672 -- dereferences of private types are legal in default expressions. This
673 -- case is taken care of in Check_Fully_Declared, called below. There
674 -- are also 2005 cases where it is legal for the prefix to be unfrozen.
676 -- This consideration also applies to similar checks for allocators,
677 -- qualified expressions, and type conversions.
679 -- An additional exception concerns other per-object expressions that
680 -- are not directly related to component declarations, in particular
681 -- representation pragmas for tasks. These will be per-object
682 -- expressions if they depend on discriminants or some global entity.
683 -- If the task has access discriminants, the designated type may be
684 -- incomplete at the point the expression is resolved. This resolution
685 -- takes place within the body of the initialization procedure, where
686 -- the discriminant is replaced by its discriminal.
690 then
693 -- Ada 2005 (AI-326): Tagged incomplete types allowed. The wrong usages
694 -- are handled by Analyze_Access_Attribute, Analyze_Assignment,
695 -- Analyze_Object_Renaming, and Freeze_Entity.
701 E_Incomplete_Type
703 then
705 else
710 ------------------------------
711 -- Check_Infinite_Recursion --
712 ------------------------------
719 -- Check whether list of actuals is identical to list of formals of
720 -- called function (which is also the enclosing scope).
722 ------------------------
723 -- Same_Argument_List --
724 ------------------------
731 begin
734 else
743 then
754 -- Start of processing for Check_Infinite_Recursion
756 begin
757 -- Special case, if this is a procedure call and is a call to the
758 -- current procedure with the same argument list, then this is for
759 -- sure an infinite recursion and we insert a call to raise SE.
763 and then Same_Argument_List
764 then
765 declare
767 begin
771 then
782 -- If not that special case, search up tree, quitting if we reach a
783 -- construct (e.g. a conditional) that tells us that this is not a
784 -- case for an infinite recursion warning.
787 loop
790 -- If no parent, then we were not inside a subprogram, this can for
791 -- example happen when processing certain pragmas in a spec. Just
792 -- return False in this case.
798 -- Done if we get to subprogram body, this is definitely an infinite
799 -- recursion case if we did not find anything to stop us.
803 -- If appearing in conditional, result is false
806 N_And_Then,
807 N_Case_Expression,
808 N_Case_Statement,
809 N_If_Expression,
810 N_If_Statement)
811 then
816 then
817 -- If the call is the expression of a return statement and the
818 -- actuals are identical to the formals, it's worth a warning.
819 -- However, we skip this if there is an immediately preceding
820 -- raise statement, since the call is never executed.
822 -- Furthermore, this corresponds to a common idiom:
824 -- function F (L : Thing) return Boolean is
825 -- begin
826 -- raise Program_Error;
827 -- return F (L);
828 -- end F;
830 -- for generating a stub function
833 and then Same_Argument_List
834 then
837 -- OK, return statement is in a statement list, look for raise
839 declare
842 begin
843 -- Skip past N_Freeze_Entity nodes generated by expansion
848 loop
852 -- If no raise statement, give warning. We look at the
853 -- original node, because in the case of "raise ... with
854 -- ...", the node has been transformed into a call.
857 and then
865 else
876 -------------------------------
877 -- Check_Initialization_Call --
878 -------------------------------
884 -- Check whether the creation of an object of the type will involve
885 -- use of the secondary stack. If T is a record type, this is true
886 -- if the expression for some component uses the secondary stack, e.g.
887 -- through a call to a function that returns an unconstrained value.
888 -- False if T is controlled, because cleanups occur elsewhere.
890 -------------
891 -- Uses_SS --
892 -------------
899 begin
900 -- Normally we want to use the underlying type, but if it's not set
901 -- then continue with T.
918 then
919 -- The expression for a dynamic component may be rewritten
920 -- as a dereference, so retrieve original node.
924 -- Return True if the expression is a call to a function
925 -- (including an attribute function such as Image, or a
926 -- user-defined operator) with a result that requires a
927 -- transient scope.
934 then
947 else
952 -- Start of processing for Check_Initialization_Call
954 begin
955 -- Establish a transient scope if the type needs it
962 ---------------------------------------
963 -- Check_No_Direct_Boolean_Operators --
964 ---------------------------------------
967 begin
970 then
971 -- Restriction only applies to original source code
983 ------------------------------
984 -- Check_Parameterless_Call --
985 ------------------------------
991 -- If the prefix is of an access_to_subprogram type, the node must be
992 -- rewritten as a call. Ditto if the prefix is overloaded and all its
993 -- interpretations are access to subprograms.
995 ---------------------------
996 -- Prefix_Is_Access_Subp --
997 ---------------------------
1003 begin
1004 -- If the context is an attribute reference that can apply to
1005 -- functions, this is never a parameterless call (RM 4.1.4(6)).
1009 Name_Code_Address,
1010 Name_Access)
1011 then
1016 return
1019 else
1024 then
1035 -- Start of processing for Check_Parameterless_Call
1037 begin
1038 -- Defend against junk stuff if errors already detected
1045 then
1052 -- If the context expects a value, and the name is a procedure, this is
1053 -- most likely a missing 'Access. Don't try to resolve the parameterless
1054 -- call, error will be caught when the outer call is analyzed.
1059 and then
1061 N_Function_Call,
1062 N_Procedure_Call_Statement)
1063 then
1067 -- Rewrite as call if overloadable entity that is (or could be, in the
1068 -- overloaded case) a function call. If we know for sure that the entity
1069 -- is an enumeration literal, we do not rewrite it.
1071 -- If the entity is the name of an operator, it cannot be a call because
1072 -- operators cannot have default parameters. In this case, this must be
1073 -- a string whose contents coincide with an operator name. Set the kind
1074 -- of the node appropriately.
1082 -- Rewrite as call if it is an explicit dereference of an expression of
1083 -- a subprogram access type, and the subprogram type is not that of a
1084 -- procedure or entry.
1086 or else
1089 -- Rewrite as call if it is a selected component which is a function,
1090 -- this is the case of a call to a protected function (which may be
1091 -- overloaded with other protected operations).
1093 or else
1096 or else
1098 E_Procedure)
1101 -- If one of the above three conditions is met, rewrite as call. Apply
1102 -- the rewriting only once.
1104 then
1107 then
1109 -- This may be a prefixed call that was not fully analyzed, e.g.
1110 -- an actual in an instance.
1115 then
1125 -- If overloaded, overload set belongs to new copy
1129 -- Change node to parameterless function call (note that the
1130 -- Parameter_Associations associations field is left set to Empty,
1131 -- its normal default value since there are no parameters)
1149 -----------------------------
1150 -- Is_Definite_Access_Type --
1151 -----------------------------
1155 begin
1161 ----------------------
1162 -- Is_Predefined_Op --
1163 ----------------------
1166 begin
1167 -- Predefined operators are intrinsic subprograms
1173 -- A call to a back-end builtin is never a predefined operator
1184 -----------------------------
1185 -- Make_Call_Into_Operator --
1186 -----------------------------
1188 procedure Make_Call_Into_Operator
1192 is
1207 -- If the operand is not universal, and the operator is given by an
1208 -- expanded name, verify that the operand has an interpretation with a
1209 -- type defined in the given scope of the operator.
1212 -- Find a type of the given class in package Pack that contains the
1213 -- operator.
1215 ---------------------------
1216 -- Operand_Type_In_Scope --
1217 ---------------------------
1224 begin
1228 else
1242 ---------------
1243 -- Type_In_P --
1244 ---------------
1250 -- Verify that node is not part of the type declaration for the
1251 -- candidate type, which would otherwise be invisible.
1253 -------------
1254 -- In_Decl --
1255 -------------
1261 begin
1270 else
1273 loop
1276 else
1285 -- Start of processing for Type_In_P
1287 begin
1288 -- If the context type is declared in the prefix package, this is the
1289 -- desired base type.
1294 else
1298 and then not In_Decl
1299 then
1310 -- Start of processing for Make_Call_Into_Operator
1312 begin
1315 -- Binary operator
1325 -- Unary operator
1327 else
1333 -- If the operator is denoted by an expanded name, and the prefix is
1334 -- not Standard, but the operator is a predefined one whose scope is
1335 -- Standard, then this is an implicit_operator, inserted as an
1336 -- interpretation by the procedure of the same name. This procedure
1337 -- overestimates the presence of implicit operators, because it does
1338 -- not examine the type of the operands. Verify now that the operand
1339 -- type appears in the given scope. If right operand is universal,
1340 -- check the other operand. In the case of concatenation, either
1341 -- argument can be the component type, so check the type of the result.
1342 -- If both arguments are literals, look for a type of the right kind
1343 -- defined in the given scope. This elaborate nonsense is brought to
1344 -- you courtesy of b33302a. The type itself must be frozen, so we must
1345 -- find the type of the proper class in the given scope.
1347 -- A final wrinkle is the multiplication operator for fixed point types,
1348 -- which is defined in Standard only, and not in the scope of the
1349 -- fixed point type itself.
1354 -- If this is a package renaming, get renamed entity, which will be
1355 -- the scope of the operands if operaton is type-correct.
1361 -- If the entity being called is defined in the given package, it is
1362 -- a renaming of a predefined operator, and known to be legal.
1366 then
1369 -- Visibility does not need to be checked in an instance: if the
1370 -- operator was not visible in the generic it has been diagnosed
1371 -- already, else there is an implicit copy of it in the instance.
1379 then
1384 -- Ada 2005 AI-420: Predefined equality on Universal_Access is
1385 -- available.
1390 then
1393 else
1402 and then Is_Binary
1404 then
1410 -- Verify that the scope contains a type that corresponds to
1411 -- the given literal. Optimize the case where Pack is Standard.
1433 else
1442 else
1451 then
1454 -- If the type is defined elsewhere, and the operator is not
1455 -- defined in the given scope (by a renaming declaration, e.g.)
1456 -- then this is an error as well. If an extension of System is
1457 -- present, and the type may be defined there, Pack must be
1458 -- System itself.
1465 then
1468 else
1474 then
1481 Error_Msg_NE
1486 -- Detect a mismatch between the context type and the result type
1487 -- in the named package, which is otherwise not detected if the
1488 -- operands are universal. Check is only needed if source entity is
1489 -- an operator, not a function that renames an operator.
1496 and then not In_Instance
1497 then
1500 then
1501 -- Already checked above
1505 -- Operator may be defined in an extension of System
1509 then
1512 else
1513 -- Could we use Wrong_Type here??? (this would require setting
1514 -- Etype (N) to the actual type found where Typ was expected).
1525 else
1529 -- If this is a call to a function that renames a predefined equality,
1530 -- the renaming declaration provides a type that must be used to
1531 -- resolve the operands. This must be done now because resolution of
1532 -- the equality node will not resolve any remaining ambiguity, and it
1533 -- assumes that the first operand is not overloaded.
1538 then
1546 -- Do rewrite setting Comes_From_Source on the result if the original
1547 -- call came from source. Although it is not strictly the case that the
1548 -- operator as such comes from the source, logically it corresponds
1549 -- exactly to the function call in the source, so it should be marked
1550 -- this way (e.g. to make sure that validity checks work fine).
1552 declare
1554 begin
1559 -- If this is an arithmetic operator and the result type is private,
1560 -- the operands and the result must be wrapped in conversion to
1561 -- expose the underlying numeric type and expand the proper checks,
1562 -- e.g. on division.
1566 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
1567 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
1576 else
1580 -- If in ASIS_Mode, propagate operand types to original actuals of
1581 -- function call, which would otherwise not be fully resolved. If
1582 -- the call has already been constant-folded, nothing to do.
1590 else
1599 -------------------
1600 -- Operator_Kind --
1601 -------------------
1603 function Operator_Kind
1606 is
1609 begin
1610 -- Use CASE statement or array???
1647 else
1651 -- Unary operators
1653 else
1662 else
1670 ----------------------------
1671 -- Preanalyze_And_Resolve --
1672 ----------------------------
1677 begin
1681 -- Normally, we suppress all checks for this preanalysis. There is no
1682 -- point in processing them now, since they will be applied properly
1683 -- and in the proper location when the default expressions reanalyzed
1684 -- and reexpanded later on. We will also have more information at that
1685 -- point for possible suppression of individual checks.
1687 -- However, in SPARK mode, most expansion is suppressed, and this
1688 -- later reanalysis and reexpansion may not occur. SPARK mode does
1689 -- require the setting of checking flags for proof purposes, so we
1690 -- do the SPARK preanalysis without suppressing checks.
1692 -- This special handling for SPARK mode is required for example in the
1693 -- case of Ada 2012 constructs such as quantified expressions, which are
1694 -- expanded in two separate steps.
1698 else
1702 Expander_Mode_Restore;
1706 -- Version without context type
1711 begin
1718 Expander_Mode_Restore;
1722 ----------------------------------
1723 -- Replace_Actual_Discriminants --
1724 ----------------------------------
1731 -- Comment needed???
1733 -------------------
1734 -- Process_Discr --
1735 -------------------
1740 begin
1746 then
1762 -- Start of processing for Replace_Actual_Discriminants
1764 begin
1778 else
1783 -------------
1784 -- Resolve --
1785 -------------
1801 -- Determine whether a node comes from a predefined library unit or
1802 -- Standard.
1805 -- Try and fix up a literal so that it matches its expected type. New
1806 -- literals are manufactured if necessary to avoid cascaded errors.
1809 -- Return the current scope. Skip loop scopes created for the purpose of
1810 -- quantified expression analysis since those do not appear in the tree.
1813 -- Additional diagnostics when an ambiguous call has an ambiguous
1814 -- argument (typically a controlling actual).
1817 -- Called when attempt at resolving current expression fails
1819 ------------------------------------
1820 -- Comes_From_Predefined_Lib_Unit --
1821 -------------------------------------
1824 begin
1825 return
1827 or else Is_Predefined_File_Name
1831 --------------------
1832 -- Patch_Up_Value --
1833 --------------------
1836 begin
1853 then
1858 Char_Literal_Value =>
1874 --------------------------
1875 -- Proper_Current_Scope --
1876 --------------------------
1881 begin
1884 -- Skip a loop scope created for quantified expression analysis
1888 then
1890 else
1898 -------------------------------
1899 -- Report_Ambiguous_Argument --
1900 -------------------------------
1907 begin
1911 then
1914 -- Could use comments on what is going on here???
1922 else
1931 -----------------------
1932 -- Resolution_Failed --
1933 -----------------------
1936 begin
1942 -- The caller will return without calling the expander, so we need
1943 -- to set the analyzed flag. Note that it is fine to set Analyzed
1944 -- to True even if we are in the middle of a shallow analysis,
1945 -- (see the spec of sem for more details) since this is an error
1946 -- situation anyway, and there is no point in repeating the
1947 -- analysis later (indeed it won't work to repeat it later, since
1948 -- we haven't got a clear resolution of which entity is being
1949 -- referenced.)
1955 -- Start of processing for Resolve
1957 begin
1962 -- Access attribute on remote subprogram cannot be used for a non-remote
1963 -- access-to-subprogram type.
1967 Name_Unrestricted_Access,
1968 Name_Unchecked_Access)
1974 then
1975 Error_Msg_N
1981 -- If the context is a Remote_Access_To_Subprogram, access attributes
1982 -- must be resolved with the corresponding fat pointer. There is no need
1983 -- to check for the attribute name since the return type of an
1984 -- attribute is never a remote type.
1989 then
1990 declare
1998 begin
1999 -- Check that Typ is a remote access-to-subprogram type
2003 -- Prefix (N) must statically denote a remote subprogram
2004 -- declared in a package specification.
2008 Attr = Attribute_Unrestricted_Access
2009 then
2024 or else
2026 then
2028 Error_Msg_N
2030 N);
2033 -- If we are generating code in distributed mode, perform
2034 -- semantic checks against corresponding remote entities.
2036 if Full_Expander_Active
2038 then
2039 Check_Subtype_Conformant
2041 Old_Id => Designated_Type
2067 then
2072 -- Return if already analyzed
2079 -- A Raise_Expression takes its type from context. The Etype was set
2080 -- to Any_Type, reflecting the fact that the expression itself does
2081 -- not specify any possible interpretation. So we set the type to the
2082 -- resolution type here and now. We need to do this before Resolve sees
2083 -- the Any_Type value.
2088 -- Any other case of Any_Type as the Etype value means that we had
2089 -- a previous error.
2098 -- The resolution of an Expression_With_Actions is determined by
2099 -- its Expression.
2107 -- If not overloaded, then we know the type, and all that needs doing
2108 -- is to check that this type is compatible with the context.
2114 -- In the overloaded case, we must select the interpretation that
2115 -- is compatible with the context (i.e. the type passed to Resolve)
2117 else
2118 -- Loop through possible interpretations
2128 -- We are only interested in interpretations that are compatible
2129 -- with the expected type, any other interpretations are ignored.
2134 Write_Eol;
2137 else
2138 -- Skip the current interpretation if it is disabled by an
2139 -- abstract operator. This action is performed only when the
2140 -- type against which we are resolving is the same as the
2141 -- type of the interpretation.
2148 then
2156 -- First matching interpretation
2164 -- Matching interpretation that is not the first, maybe an
2165 -- error, but there are some cases where preference rules are
2166 -- used to choose between the two possibilities. These and
2167 -- some more obscure cases are handled in Disambiguate.
2169 else
2170 -- If the current statement is part of a predefined library
2171 -- unit, then all interpretations which come from user level
2172 -- packages should not be considered.
2174 if From_Lib
2176 then
2183 -- Disambiguation has succeeded. Skip the remaining
2184 -- interpretations.
2194 else
2195 -- Before we issue an ambiguity complaint, check for
2196 -- the case of a subprogram call where at least one
2197 -- of the arguments is Any_Type, and if so, suppress
2198 -- the message, since it is a cascaded error.
2201 declare
2205 begin
2217 Write_Eol;
2230 then
2235 then
2239 -- Not that special case, so issue message using the
2240 -- flag Ambiguous to control printing of the header
2241 -- message only at the start of an ambiguous set.
2246 then
2247 Error_Msg_N
2250 else
2251 Error_Msg_NE -- CODEFIX
2259 Error_Msg_N
2261 else
2262 Error_Msg_N -- CODEFIX
2268 then
2269 Report_Ambiguous_Argument;
2275 -- By default, the error message refers to the candidate
2276 -- interpretation. But if it is a predefined operator, it
2277 -- is implicitly declared at the declaration of the type
2278 -- of the operand. Recover the sloc of that declaration
2279 -- for the error message.
2285 Standard_Standard
2286 then
2291 then
2299 Standard_Standard
2300 then
2305 then
2309 -- If this is an indirect call, use the subprogram_type
2310 -- in the message, to have a meaningful location. Also
2311 -- indicate if this is an inherited operation, created
2312 -- by a type declaration.
2317 then
2319 Error_Msg_Sloc :=
2321 else
2328 then
2329 -- Special-case the message for universal_fixed
2330 -- operators, which are not declared with the type
2331 -- of the operand, but appear forever in Standard.
2335 then
2336 Error_Msg_N
2339 else
2340 Error_Msg_N
2344 elsif
2346 then
2347 Error_Msg_N
2349 else
2350 Error_Msg_N -- CODEFIX
2357 -- We have a matching interpretation, Expr_Type is the type
2358 -- from this interpretation, and Seen is the entity.
2360 -- For an operator, just set the entity name. The type will be
2361 -- set by the specific operator resolution routine.
2376 -- AI05-0139-2: Expression is overloaded because type has
2377 -- implicit dereference. If type matches context, no implicit
2378 -- dereference is involved.
2389 then
2392 -- For an explicit dereference, attribute reference, range,
2393 -- short-circuit form (which is not an operator node), or call
2394 -- with a name that is an explicit dereference, there is
2395 -- nothing to be done at this point.
2398 N_Attribute_Reference,
2399 N_And_Then,
2400 N_Indexed_Component,
2401 N_Or_Else,
2402 N_Range,
2403 N_Selected_Component,
2404 N_Slice)
2406 then
2409 -- For procedure or function calls, set the type of the name,
2410 -- and also the entity pointer for the prefix.
2414 then
2421 then
2426 -- For all other cases, just set the type of the Name
2428 else
2436 -- Move to next interpretation
2444 -- At this stage Found indicates whether or not an acceptable
2445 -- interpretation exists. If not, then we have an error, except that if
2446 -- the context is Any_Type as a result of some other error, then we
2447 -- suppress the error report.
2452 -- If type we are looking for is Void, then this is the procedure
2453 -- call case, and the error is simply that what we gave is not a
2454 -- procedure name (we think of procedure calls as expressions with
2455 -- types internally, but the user doesn't think of them this way!)
2459 -- Special case message if function used as a procedure
2464 then
2465 Error_Msg_NE
2469 -- Otherwise give general message (not clear what cases this
2470 -- covers, but no harm in providing for them!)
2472 else
2478 -- Otherwise we do have a subexpression with the wrong type
2480 -- Check for the case of an allocator which uses an access type
2481 -- instead of the designated type. This is a common error and we
2482 -- specialize the message, posting an error on the operand of the
2483 -- allocator, complaining that we expected the designated type of
2484 -- the allocator.
2490 then
2494 -- Check for view mismatch on Null in instances, for which the
2495 -- view-swapping mechanism has no identifier.
2501 then
2506 -- Check for an aggregate. Sometimes we can get bogus aggregates
2507 -- from misuse of parentheses, and we are about to complain about
2508 -- the aggregate without even looking inside it.
2510 -- Instead, if we have an aggregate of type Any_Composite, then
2511 -- analyze and resolve the component fields, and then only issue
2512 -- another message if we get no errors doing this (otherwise
2513 -- assume that the errors in the aggregate caused the problem).
2517 then
2518 -- Disable expansion in any case. If there is a type mismatch
2519 -- it may be fatal to try to expand the aggregate. The flag
2520 -- would otherwise be set to false when the error is posted.
2524 declare
2526 -- Check one aggregate, and set Found to True if we have a
2527 -- definite error in any of its elements
2530 -- Check one element of aggregate and set Found to True if
2531 -- we definitely have an error in the element.
2533 ----------------
2534 -- Check_Aggr --
2535 ----------------
2540 begin
2553 -- If this is a default-initialized component, then
2554 -- there is nothing to check. The box will be
2555 -- replaced by the appropriate call during late
2556 -- expansion.
2567 ----------------
2568 -- Check_Elmt --
2569 ----------------
2572 begin
2573 -- If we have a nested aggregate, go inside it (to
2574 -- attempt a naked analyze-resolve of the aggregate can
2575 -- cause undesirable cascaded errors). Do not resolve
2576 -- expression if it needs a type from context, as for
2577 -- integer * fixed expression.
2582 else
2587 then
2597 begin
2602 -- If an error message was issued already, Found got reset to
2603 -- True, so if it is still False, issue standard Wrong_Type msg.
2608 then
2609 declare
2611 begin
2617 -- Protected operation: retrieve operation name
2621 else
2626 Error_Msg_NE
2632 declare
2636 begin
2643 Error_Msg_NE
2649 else
2653 else
2659 Resolution_Failed;
2662 -- Test if we have more than one interpretation for the context
2665 Resolution_Failed;
2668 -- Only one intepretation
2670 else
2671 -- In Ada 2005, if we have something like "X : T := 2 + 2;", where
2672 -- the "+" on T is abstract, and the operands are of universal type,
2673 -- the above code will have (incorrectly) resolved the "+" to the
2674 -- universal one in Standard. Therefore check for this case and give
2675 -- an error. We can't do this earlier, because it would cause legal
2676 -- cases to get errors (when some other type has an abstract "+").
2682 then
2687 then
2688 Error_Msg_NE
2697 -- Here we have an acceptable interpretation for the context
2699 -- Propagate type information and normalize tree for various
2700 -- predefined operations. If the context only imposes a class of
2701 -- types, rather than a specific type, propagate the actual type
2702 -- downward.
2708 Typ = Any_Discrete
2709 then
2712 -- Any_Fixed is legal in a real context only if a specific fixed-
2713 -- point type is imposed. If Norman Cohen can be confused by this,
2714 -- it deserves a separate message.
2718 then
2725 -- A user-defined operator is transformed into a function call at
2726 -- this point, so that further processing knows that operators are
2727 -- really operators (i.e. are predefined operators). User-defined
2728 -- operators that are intrinsic are just renamings of the predefined
2729 -- ones, and need not be turned into calls either, but if they rename
2730 -- a different operator, we must transform the node accordingly.
2731 -- Instantiations of Unchecked_Conversion are intrinsic but are
2732 -- treated as functions, even if given an operator designator.
2737 then
2743 and then
2745 N_Subprogram_Renaming_Declaration
2746 then
2749 -- If the node is rewritten, it will be fully resolved in
2750 -- Rewrite_Renamed_Operator.
2760 when N_Aggregate => Resolve_Aggregate (N, Ctx_Type);
2762 when N_Allocator => Resolve_Allocator (N, Ctx_Type);
2764 when N_Short_Circuit
2765 => Resolve_Short_Circuit (N, Ctx_Type);
2767 when N_Attribute_Reference
2768 => Resolve_Attribute (N, Ctx_Type);
2770 when N_Case_Expression
2771 => Resolve_Case_Expression (N, Ctx_Type);
2773 when N_Character_Literal
2774 => Resolve_Character_Literal (N, Ctx_Type);
2776 when N_Expanded_Name
2777 => Resolve_Entity_Name (N, Ctx_Type);
2779 when N_Explicit_Dereference
2780 => Resolve_Explicit_Dereference (N, Ctx_Type);
2782 when N_Expression_With_Actions
2783 => Resolve_Expression_With_Actions (N, Ctx_Type);
2785 when N_Extension_Aggregate
2786 => Resolve_Extension_Aggregate (N, Ctx_Type);
2788 when N_Function_Call
2789 => Resolve_Call (N, Ctx_Type);
2791 when N_Identifier
2792 => Resolve_Entity_Name (N, Ctx_Type);
2794 when N_If_Expression
2795 => Resolve_If_Expression (N, Ctx_Type);
2797 when N_Indexed_Component
2798 => Resolve_Indexed_Component (N, Ctx_Type);
2800 when N_Integer_Literal
2801 => Resolve_Integer_Literal (N, Ctx_Type);
2803 when N_Membership_Test
2804 => Resolve_Membership_Op (N, Ctx_Type);
2806 when N_Null => Resolve_Null (N, Ctx_Type);
2808 when N_Op_And | N_Op_Or | N_Op_Xor
2809 => Resolve_Logical_Op (N, Ctx_Type);
2811 when N_Op_Eq | N_Op_Ne
2812 => Resolve_Equality_Op (N, Ctx_Type);
2814 when N_Op_Lt | N_Op_Le | N_Op_Gt | N_Op_Ge
2815 => Resolve_Comparison_Op (N, Ctx_Type);
2817 when N_Op_Not => Resolve_Op_Not (N, Ctx_Type);
2819 when N_Op_Add | N_Op_Subtract | N_Op_Multiply |
2820 N_Op_Divide | N_Op_Mod | N_Op_Rem
2822 => Resolve_Arithmetic_Op (N, Ctx_Type);
2824 when N_Op_Concat => Resolve_Op_Concat (N, Ctx_Type);
2826 when N_Op_Expon => Resolve_Op_Expon (N, Ctx_Type);
2828 when N_Op_Plus | N_Op_Minus | N_Op_Abs
2829 => Resolve_Unary_Op (N, Ctx_Type);
2831 when N_Op_Shift => Resolve_Shift (N, Ctx_Type);
2833 when N_Procedure_Call_Statement
2834 => Resolve_Call (N, Ctx_Type);
2836 when N_Operator_Symbol
2837 => Resolve_Operator_Symbol (N, Ctx_Type);
2839 when N_Qualified_Expression
2840 => Resolve_Qualified_Expression (N, Ctx_Type);
2842 -- Why is the following null, needs a comment ???
2844 when N_Quantified_Expression
2845 => null;
2847 -- Nothing to do for Raise_Expression, since we took care of
2848 -- setting the Etype earlier, and no other processing is needed.
2850 when N_Raise_Expression
2851 => null;
2853 when N_Raise_xxx_Error
2854 => Set_Etype (N, Ctx_Type);
2856 when N_Range => Resolve_Range (N, Ctx_Type);
2858 when N_Real_Literal
2859 => Resolve_Real_Literal (N, Ctx_Type);
2861 when N_Reference => Resolve_Reference (N, Ctx_Type);
2863 when N_Selected_Component
2864 => Resolve_Selected_Component (N, Ctx_Type);
2866 when N_Slice => Resolve_Slice (N, Ctx_Type);
2868 when N_String_Literal
2869 => Resolve_String_Literal (N, Ctx_Type);
2871 when N_Subprogram_Info
2872 => Resolve_Subprogram_Info (N, Ctx_Type);
2874 when N_Type_Conversion
2875 => Resolve_Type_Conversion (N, Ctx_Type);
2877 when N_Unchecked_Expression =>
2878 Resolve_Unchecked_Expression (N, Ctx_Type);
2880 when N_Unchecked_Type_Conversion =>
2881 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
2882 end case;
2884 -- Ada 2012 (AI05-0149): Apply an (implicit) conversion to an
2885 -- expression of an anonymous access type that occurs in the context
2886 -- of a named general access type, except when the expression is that
2887 -- of a membership test. This ensures proper legality checking in
2888 -- terms of allowed conversions (expressions that would be illegal to
2889 -- convert implicitly are allowed in membership tests).
2891 if Ada_Version >= Ada_2012
2892 and then Ekind (Ctx_Type) = E_General_Access_Type
2893 and then Ekind (Etype (N)) = E_Anonymous_Access_Type
2894 and then Nkind (Parent (N)) not in N_Membership_Test
2895 then
2896 Rewrite (N, Convert_To (Ctx_Type, Relocate_Node (N)));
2897 Analyze_And_Resolve (N, Ctx_Type);
2898 end if;
2900 -- If the subexpression was replaced by a non-subexpression, then
2901 -- all we do is to expand it. The only legitimate case we know of
2902 -- is converting procedure call statement to entry call statements,
2903 -- but there may be others, so we are making this test general.
2905 if Nkind (N) not in N_Subexpr then
2906 Debug_A_Exit ("resolving ", N, " (done)");
2907 Expand (N);
2908 return;
2909 end if;
2911 -- The expression is definitely NOT overloaded at this point, so
2912 -- we reset the Is_Overloaded flag to avoid any confusion when
2913 -- reanalyzing the node.
2915 Set_Is_Overloaded (N, False);
2917 -- Freeze expression type, entity if it is a name, and designated
2918 -- type if it is an allocator (RM 13.14(10,11,13)).
2920 -- Now that the resolution of the type of the node is complete, and
2921 -- we did not detect an error, we can expand this node. We skip the
2922 -- expand call if we are in a default expression, see section
2923 -- "Handling of Default Expressions" in Sem spec.
2925 Debug_A_Exit ("resolving ", N, " (done)");
2927 -- We unconditionally freeze the expression, even if we are in
2928 -- default expression mode (the Freeze_Expression routine tests this
2929 -- flag and only freezes static types if it is set).
2931 -- Ada 2012 (AI05-177): Expression functions do not freeze. Only
2932 -- their use (in an expanded call) freezes.
2934 if Ekind (Proper_Current_Scope) /= E_Function
2935 or else Nkind (Original_Node (Unit_Declaration_Node
2936 (Proper_Current_Scope))) /= N_Expression_Function
2937 then
2938 Freeze_Expression (N);
2939 end if;
2941 -- Now we can do the expansion
2943 Expand (N);
2944 end if;
2945 end Resolve;
2947 -------------
2948 -- Resolve --
2949 -------------
2951 -- Version with check(s) suppressed
2953 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
2954 begin
2955 if Suppress = All_Checks then
2956 declare
2957 Sva : constant Suppress_Array := Scope_Suppress.Suppress;
2958 begin
2959 Scope_Suppress.Suppress := (others => True);
2960 Resolve (N, Typ);
2961 Scope_Suppress.Suppress := Sva;
2962 end;
2964 else
2965 declare
2966 Svg : constant Boolean := Scope_Suppress.Suppress (Suppress);
2967 begin
2968 Scope_Suppress.Suppress (Suppress) := True;
2969 Resolve (N, Typ);
2970 Scope_Suppress.Suppress (Suppress) := Svg;
2971 end;
2972 end if;
2973 end Resolve;
2975 -------------
2976 -- Resolve --
2977 -------------
2979 -- Version with implicit type
2981 procedure Resolve (N : Node_Id) is
2982 begin
2983 Resolve (N, Etype (N));
2984 end Resolve;
2986 ---------------------
2987 -- Resolve_Actuals --
2988 ---------------------
2990 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
2991 Loc : constant Source_Ptr := Sloc (N);
2992 A : Node_Id;
2993 F : Entity_Id;
2994 A_Typ : Entity_Id;
2995 F_Typ : Entity_Id;
2996 Prev : Node_Id := Empty;
2997 Orig_A : Node_Id;
2999 procedure Check_Argument_Order;
3000 -- Performs a check for the case where the actuals are all simple
3001 -- identifiers that correspond to the formal names, but in the wrong
3002 -- order, which is considered suspicious and cause for a warning.
3004 procedure Check_Prefixed_Call;
3005 -- If the original node is an overloaded call in prefix notation,
3007 -- Try_Object_Operation has already verified that there is a valid
3008 -- interpretation, but the form of the actual can only be determined
3009 -- once the primitive operation is identified.
3012 -- If the actual is missing in a call, insert in the actuals list
3013 -- an instance of the default expression. The insertion is always
3014 -- a named association.
3017 -- Check whether T1 and T2, or their full views, are derived from a
3018 -- common type. Used to enforce the restrictions on array conversions
3019 -- of AI95-00246.
3022 -- Predicate to determine whether an actual that is a concatenation
3023 -- will be evaluated statically and does not need a transient scope.
3024 -- This must be determined before the actual is resolved and expanded
3025 -- because if needed the transient scope must be introduced earlier.
3027 --------------------------
3028 -- Check_Argument_Order --
3029 --------------------------
3032 begin
3033 -- Nothing to do if no parameters, or original node is neither a
3034 -- function call nor a procedure call statement (happens in the
3035 -- operator-transformed-to-function call case), or the call does
3036 -- not come from source, or this warning is off.
3038 if not Warn_On_Parameter_Order
3042 then
3046 declare
3049 begin
3050 -- Nothing to do if only one parameter
3056 -- Here if at least two arguments
3058 declare
3064 -- Set True if an out of order case is found
3066 begin
3067 -- Collect identifier names of actuals, fail if any actual is
3068 -- not a simple identifier, and record max length of name.
3074 else
3080 -- If we got this far, all actuals are identifiers and the list
3081 -- of their names is stored in the Actuals array.
3086 -- If we ran out of formals, that's odd, probably an error
3087 -- which will be detected elsewhere, but abandon the search.
3093 -- If name matches and is in order OK
3098 else
3099 -- If no match, see if it is elsewhere in list and if so
3100 -- flag potential wrong order if type is compatible.
3104 and then
3106 then
3112 -- No match
3120 -- If Formals left over, also probably an error, skip warning
3126 -- Here we give the warning if something was out of order
3129 Error_Msg_N
3136 -------------------------
3137 -- Check_Prefixed_Call --
3138 -------------------------
3147 begin
3148 -- Check whether the call is a prefixed call, with or without
3149 -- additional actuals.
3152 or else
3158 then
3161 then
3162 -- Introduce dereference on object in prefix
3164 New_A :=
3172 then
3173 -- Introduce an implicit 'Access in prefix
3176 Error_Msg_NE
3192 --------------------
3193 -- Insert_Default --
3194 --------------------
3200 begin
3201 -- Missing argument in call, nothing to insert
3206 else
3207 -- Note that we do a full New_Copy_Tree, so that any associated
3208 -- Itypes are properly copied. This may not be needed any more,
3209 -- but it does no harm as a safety measure! Defaults of a generic
3210 -- formal may be out of bounds of the corresponding actual (see
3211 -- cc1311b) and an additional check may be required.
3213 Actval :=
3214 New_Copy_Tree
3221 then
3227 then
3230 then
3231 -- If default is a real literal, do not introduce a
3232 -- conversion whose effect may depend on the run-time
3233 -- size of universal real.
3237 else
3248 -- Resolve aggregates with their base type, to avoid scope
3249 -- anomalies: the subtype was first built in the subprogram
3250 -- declaration, and the current call may be nested.
3254 else
3258 else
3261 -- See note above concerning aggregates
3265 then
3268 -- Resolve entities with their own type, which may differ from
3269 -- the type of a reference in a generic context (the view
3270 -- swapping mechanism did not anticipate the re-analysis of
3271 -- default values in calls).
3276 else
3281 -- If default is a tag indeterminate function call, propagate tag
3282 -- to obtain proper dispatching.
3286 then
3292 -- If the default expression raises constraint error, then just
3293 -- silently replace it with an N_Raise_Constraint_Error node, since
3294 -- we already gave the warning on the subprogram spec. If node is
3295 -- already a Raise_Constraint_Error leave as is, to prevent loops in
3296 -- the warnings removal machinery.
3300 then
3308 Assoc :=
3313 -- Case of insertion is first named actual
3317 then
3324 else
3328 else
3332 -- Case of insertion is not first named actual
3334 else
3335 Set_Next_Named_Actual
3347 -------------------
3348 -- Same_Ancestor --
3349 -------------------
3355 begin
3358 then
3364 then
3371 --------------------------
3372 -- Static_Concatenation --
3373 --------------------------
3376 begin
3383 -- Concatenation is static when both operands are static and
3384 -- the concatenation operator is a predefined one.
3387 and then
3389 and then
3394 declare
3396 begin
3399 and then
3403 else
3409 -- Start of processing for Resolve_Actuals
3411 begin
3412 Check_Argument_Order;
3416 Check_Prefixed_Call;
3425 -- If we have an error in any actual or formal, indicated by a type
3426 -- of Any_Type, then abandon resolution attempt, and set result type
3427 -- to Any_Type.
3431 then
3436 -- Case where actual is present
3438 -- If the actual is an entity, generate a reference to it now. We
3439 -- do this before the actual is resolved, because a formal of some
3440 -- protected subprogram, or a task discriminant, will be rewritten
3441 -- during expansion, and the source entity reference may be lost.
3446 then
3452 then
3459 -- RM 6.4.1(12): For an out parameter that is passed by
3460 -- copy, the formal parameter object is created, and:
3462 -- * For an access type, the formal parameter is initialized
3463 -- from the value of the actual, without checking that the
3464 -- value satisfies any constraint, any predicate, or any
3465 -- exclusion of the null value.
3467 -- * For a scalar type that has the Default_Value aspect
3468 -- specified, the formal parameter is initialized from the
3469 -- value of the actual, without checking that the value
3470 -- satisfies any constraint or any predicate.
3471 -- I do not understand why this case is included??? this is
3472 -- not a case where an OUT parameter is treated as IN OUT.
3474 -- * For a composite type with discriminants or that has
3475 -- implicit initial values for any subcomponents, the
3476 -- behavior is as for an in out parameter passed by copy.
3478 -- Hence for these cases we generate the read reference now
3479 -- (the write reference will be generated later by
3480 -- Note_Possible_Modification).
3483 and then
3485 or else
3487 and then
3489 or else
3492 or else Is_Partially_Initialized_Type
3494 then
3504 then
3505 -- If style checking mode on, check match of formal name
3513 -- If the formal is Out or In_Out, do not resolve and expand the
3514 -- conversion, because it is subsequently expanded into explicit
3515 -- temporaries and assignments. However, the object of the
3516 -- conversion can be resolved. An exception is the case of tagged
3517 -- type conversion with a class-wide actual. In that case we want
3518 -- the tag check to occur and no temporary will be needed (no
3519 -- representation change can occur) and the parameter is passed by
3520 -- reference, so we go ahead and resolve the type conversion.
3521 -- Another exception is the case of reference to component or
3522 -- subcomponent of a bit-packed array, in which case we want to
3523 -- defer expansion to the point the in and out assignments are
3524 -- performed.
3529 then
3532 then
3533 -- In a view conversion, the conversion must be legal in
3534 -- both directions, and thus both component types must be
3535 -- aliased, or neither (4.6 (8)).
3537 -- The extra rule in 4.6 (24.9.2) seems unduly restrictive:
3538 -- the privacy requirement should not apply to generic
3539 -- types, and should be checked in an instance. ARG query
3540 -- is in order ???
3544 then
3545 Error_Msg_N
3549 -- Comment here??? what set of cases???
3551 elsif
3553 then
3554 -- Check view conv between unrelated by ref array types
3558 then
3559 Error_Msg_N
3563 -- In Ada 2005 mode, check view conversion component
3564 -- type cannot be private, tagged, or volatile. Note
3565 -- that we only apply this to source conversions. The
3566 -- generated code can contain conversions which are
3567 -- not subject to this test, and we cannot extract the
3568 -- component type in such cases since it is not present.
3572 then
3573 declare
3575 Component_Type
3577 begin
3582 then
3583 Error_Msg_N
3594 -- Resolve expression if conversion is all OK
3599 then
3603 -- If the actual is a function call that returns a limited
3604 -- unconstrained object that needs finalization, create a
3605 -- transient scope for it, so that it can receive the proper
3606 -- finalization list.
3611 and then Full_Expander_Active
3613 then
3617 -- A small optimization: if one of the actuals is a concatenation
3618 -- create a block around a procedure call to recover stack space.
3619 -- This alleviates stack usage when several procedure calls in
3620 -- the same statement list use concatenation. We do not perform
3621 -- this wrapping for code statements, where the argument is a
3622 -- static string, and we want to preserve warnings involving
3623 -- sequences of such statements.
3627 and then Full_Expander_Active
3628 and then
3632 then
3636 else
3640 and then
3643 then
3644 Error_Msg_N
3657 -- (Ada 2005: AI-251): If the actual is an allocator whose
3658 -- directly designated type is a class-wide interface, we build
3659 -- an anonymous access type to use it as the type of the
3660 -- allocator. Later, when the subprogram call is expanded, if
3661 -- the interface has a secondary dispatch table the expander
3662 -- will add a type conversion to force the correct displacement
3663 -- of the pointer.
3666 declare
3672 begin
3675 then
3678 Set_Directly_Designated_Type
3683 -- Ada 2005, AI-162:If the actual is an allocator, the
3684 -- innermost enclosing statement is the master of the
3685 -- created object. This needs to be done with expansion
3686 -- enabled only, otherwise the transient scope will not
3687 -- be removed in the expansion of the wrapped construct.
3690 and then Full_Expander_Active
3691 then
3701 -- (Ada 2005): The call may be to a primitive operation of a
3702 -- tagged synchronized type, declared outside of the type. In
3703 -- this case the controlling actual must be converted to its
3704 -- corresponding record type, which is the formal type. The
3705 -- actual may be a subtype, either because of a constraint or
3706 -- because it is a generic actual, so use base type to locate
3707 -- concurrent type.
3714 then
3715 -- If the actual is overloaded, look for an interpretation
3716 -- that has a synchronized type.
3721 else
3722 declare
3726 begin
3731 then
3741 declare
3744 begin
3747 else
3751 -- Tagged synchronized type (case 1): the actual is a
3752 -- concurrent type.
3756 then
3758 Unchecked_Convert_To
3762 -- Tagged synchronized type (case 2): the formal is a
3763 -- concurrent type.
3766 and then Present
3771 then
3774 -- Common case
3776 else
3781 -- Not a synchronized operation
3783 else
3793 N_Procedure_Call_Statement)
3794 then
3795 -- In formal mode, check that actual parameters matching
3796 -- formals of tagged types are objects (or ancestor type
3797 -- conversions of objects), not general expressions.
3804 declare
3809 begin
3811 Check_SPARK_Restriction
3814 -- In formal mode, the only view conversions are those
3815 -- involving ancestor conversion of an extended type.
3817 elsif not
3823 then
3824 if Ekind_In
3826 then
3827 Check_SPARK_Restriction
3830 else
3831 Check_SPARK_Restriction
3835 else
3840 else
3844 -- In formal mode, the only view conversions are those
3845 -- involving ancestor conversion of an extended type.
3849 then
3850 Check_SPARK_Restriction
3856 -- has warnings suppressed, then we reset Never_Set_In_Source for
3857 -- the calling entity. The reason for this is to catch cases like
3858 -- GNAT.Spitbol.Patterns.Vstring_Var where the called subprogram
3859 -- uses trickery to modify an IN parameter.
3866 then
3870 -- Perform error checks for IN and IN OUT parameters
3874 -- Check unset reference. For scalar parameters, it is clearly
3875 -- wrong to pass an uninitialized value as either an IN or
3876 -- IN-OUT parameter. For composites, it is also clearly an
3877 -- error to pass a completely uninitialized value as an IN
3878 -- parameter, but the case of IN OUT is trickier. We prefer
3879 -- not to give a warning here. For example, suppose there is
3880 -- a routine that sets some component of a record to False.
3881 -- It is perfectly reasonable to make this IN-OUT and allow
3882 -- either initialized or uninitialized records to be passed
3883 -- in this case.
3885 -- For partially initialized composite values, we also avoid
3886 -- warnings, since it is quite likely that we are passing a
3887 -- partially initialized value and only the initialized fields
3888 -- will in fact be read in the subprogram.
3893 then
3897 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
3898 -- actual to a nested call, since this is case of reading an
3899 -- out parameter, which is not allowed.
3904 then
3909 -- Case of OUT or IN OUT parameter
3913 -- For an Out parameter, check for useless assignment. Note
3914 -- that we can't set Last_Assignment this early, because we may
3915 -- kill current values in Resolve_Call, and that call would
3916 -- clobber the Last_Assignment field.
3918 -- Note: call Warn_On_Useless_Assignment before doing the check
3919 -- below for Is_OK_Variable_For_Out_Formal so that the setting
3920 -- of Referenced_As_LHS/Referenced_As_Out_Formal properly
3921 -- reflects the last assignment, not this one!
3928 then
3933 -- Validate the form of the actual. Note that the call to
3934 -- Is_OK_Variable_For_Out_Formal generates the required
3935 -- reference in this case.
3937 -- A call to an initialization procedure for an aggregate
3938 -- component may initialize a nested component of a constant
3939 -- designated object. In this context the object is variable.
3943 then
3947 and then
3950 then
3951 Error_Msg_N
3957 -- What's the following about???
3961 else
3962 Kill_All_Checks;
3971 -- Apply appropriate range checks for in, out, and in-out
3972 -- parameters. Out and in-out parameters also need a separate
3973 -- check, if there is a type conversion, to make sure the return
3974 -- value meets the constraints of the variable before the
3975 -- conversion.
3977 -- Gigi looks at the check flag and uses the appropriate types.
3978 -- For now since one flag is used there is an optimization which
3979 -- might not be done in the In Out case since Gigi does not do
3980 -- any analysis. More thought required about this ???
3984 -- Apply predicate checks, unless this is a call to the
3985 -- predicate check function itself, which would cause an
3986 -- infinite recursion, or it is a call to an initialization
3987 -- procedure whose operand is of course an unfinished object.
3991 or else
3994 then
3998 -- Apply required constraint checks
4011 then
4017 then
4023 then
4026 else
4030 -- Ada 2005 (AI-231): Note that the controlling parameter case
4031 -- already existed in Ada 95, which is partially checked
4032 -- elsewhere (see Checks), and we don't want the warning
4033 -- message to differ.
4038 then
4040 Apply_Compile_Time_Constraint_Error
4046 Apply_Compile_Time_Constraint_Error
4058 Apply_Scalar_Range_Check
4060 else
4061 Apply_Range_Check
4065 else
4070 then
4072 else
4078 -- An actual associated with an access parameter is implicitly
4079 -- converted to the anonymous access type of the formal and must
4080 -- satisfy the legality checks for access conversions.
4084 Error_Msg_N
4088 -- If the actual is an access selected component of a variable,
4089 -- the call may modify its designated object. It is reasonable
4090 -- to treat this as a potential modification of the enclosing
4091 -- record, to prevent spurious warnings that it should be
4092 -- declared as a constant, because intuitively programmers
4093 -- regard the designated subcomponent as part of the record.
4098 then
4103 -- Check bad case of atomic/volatile argument (RM C.6(12))
4107 then
4110 then
4111 Error_Msg_NE
4117 then
4118 Error_Msg_NE
4124 -- Check that subprograms don't have improper controlling
4125 -- arguments (RM 3.9.2 (9)).
4127 -- A primitive operation may have an access parameter of an
4128 -- incomplete tagged type, but a dispatching call is illegal
4129 -- if the type is still incomplete.
4135 declare
4137 begin
4141 then
4142 Error_Msg_NE
4156 then
4161 then
4163 Error_Msg_NE
4167 -- Apply the checks described in 3.10.2(27): if the context is a
4168 -- specific access-to-object, the actual cannot be class-wide.
4169 -- Use base type to exclude access_to_subprogram cases.
4176 and then
4181 -- Disable these checks for call to imported C++ subprograms
4183 and then not
4187 then
4188 Error_Msg_N
4193 Error_Msg_NE
4200 -- If it is a named association, treat the selector_name as a
4201 -- proper identifier, and mark the corresponding entity.
4205 -- Ignore reference in SPARK mode, as it refers to an entity not
4206 -- in scope at the point of reference, so the reference should
4207 -- be ignored for computing effects of subprograms.
4209 and then not SPARK_Mode
4210 then
4225 -- Case where actual is not present
4227 else
4228 Insert_Default;
4235 -----------------------
4236 -- Resolve_Allocator --
4237 -----------------------
4249 procedure Check_Allocator_Discrim_Accessibility
4252 -- Check that accessibility level associated with an access discriminant
4253 -- initialized in an allocator by the expression Disc_Exp is not deeper
4254 -- than the level of the allocator type Alloc_Typ. An error message is
4255 -- issued if this condition is violated. Specialized checks are done for
4256 -- the cases of a constraint expression which is an access attribute or
4257 -- an access discriminant.
4260 -- If the allocator is an actual in a call, it is allowed to be class-
4261 -- wide when the context is not because it is a controlling actual.
4263 -------------------------------------------
4264 -- Check_Allocator_Discrim_Accessibility --
4265 -------------------------------------------
4267 procedure Check_Allocator_Discrim_Accessibility
4270 is
4271 begin
4274 then
4275 Error_Msg_N
4278 -- When the expression is an Access attribute the level of the prefix
4279 -- object must not be deeper than that of the allocator's type.
4283 Attribute_Access
4286 then
4287 Error_Msg_N
4289 Disc_Exp);
4291 -- When the expression is an access discriminant the check is against
4292 -- the level of the prefix object.
4298 then
4299 Error_Msg_N
4301 Disc_Exp);
4303 -- All other cases are legal
4305 else
4310 ----------------------------
4311 -- In_Dispatching_Context --
4312 ----------------------------
4317 begin
4323 -- Start of processing for Resolve_Allocator
4325 begin
4326 -- Replace general access with specific type
4336 -- For qualified expression, resolve the expression using the given
4337 -- subtype (nothing to do for type mark, subtype indication)
4342 and then not In_Dispatching_Context
4343 then
4344 Error_Msg_N
4351 -- A qualified expression requires an exact match of the type.
4352 -- Class-wide matching is not allowed.
4357 then
4361 -- Calls to build-in-place functions are not currently supported in
4362 -- allocators for access types associated with a simple storage pool.
4363 -- Supporting such allocators may require passing additional implicit
4364 -- parameters to build-in-place functions (or a significant revision
4365 -- of the current b-i-p implementation to unify the handling for
4366 -- multiple kinds of storage pools). ???
4370 then
4371 declare
4374 begin
4376 and then
4377 Present (Get_Rep_Pragma
4379 then
4380 Error_Msg_N
4387 -- A special accessibility check is needed for allocators that
4388 -- constrain access discriminants. The level of the type of the
4389 -- expression used to constrain an access discriminant cannot be
4390 -- deeper than the type of the allocator (in contrast to access
4391 -- parameters, where the level of the actual can be arbitrary).
4393 -- We can't use Valid_Conversion to perform this check because in
4394 -- general the type of the allocator is unrelated to the type of
4395 -- the access discriminant.
4399 then
4406 then
4409 -- Get the first component expression of the aggregate
4419 else
4423 else
4442 else
4447 else
4456 -- For a subtype mark or subtype indication, freeze the subtype
4458 else
4462 Error_Msg_N
4466 -- A special accessibility check is needed for allocators that
4467 -- constrain access discriminants. The level of the type of the
4468 -- expression used to constrain an access discriminant cannot be
4469 -- deeper than the type of the allocator (in contrast to access
4470 -- parameters, where the level of the actual can be arbitrary).
4471 -- We can't use Valid_Conversion to perform this check because
4472 -- in general the type of the allocator is unrelated to the type
4473 -- of the access discriminant.
4478 then
4488 else
4502 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
4503 -- check that the level of the type of the created object is not deeper
4504 -- than the level of the allocator's access type, since extensions can
4505 -- now occur at deeper levels than their ancestor types. This is a
4506 -- static accessibility level check; a run-time check is also needed in
4507 -- the case of an initialized allocator with a class-wide argument (see
4508 -- Expand_Allocator_Expression).
4512 then
4513 declare
4516 begin
4521 else
4527 then
4529 Error_Msg_N
4532 Error_Msg_N
4539 -- Do not apply Ada 2005 accessibility checks on a class-wide
4540 -- allocator if the type given in the allocator is a formal
4541 -- type. A run-time check will be performed in the instance.
4551 -- Check for allocation from an empty storage pool
4556 -- If the context is an unchecked conversion, as may happen within an
4557 -- inlined subprogram, the allocator is being resolved with its own
4558 -- anonymous type. In that case, if the target type has a specific
4559 -- storage pool, it must be inherited explicitly by the allocator type.
4563 then
4564 Set_Associated_Storage_Pool
4572 -- Check that an allocator with task parts isn't for a nested access
4573 -- type when restriction No_Task_Hierarchy applies.
4577 then
4581 -- An erroneous allocator may be rewritten as a raise Program_Error
4582 -- statement.
4586 -- An anonymous access discriminant is the definition of a
4587 -- coextension.
4591 N_Discriminant_Specification
4592 then
4593 declare
4597 begin
4600 -- Ada 2012 AI05-0052: If the designated type of the allocator
4601 -- is limited, then the allocator shall not be used to define
4602 -- the value of an access discriminant unless the discriminated
4603 -- type is immutably limited.
4608 then
4609 Error_Msg_N
4615 -- Avoid marking an allocator as a dynamic coextension if it is
4616 -- within a static construct.
4622 -- Cleanup for potential static coextensions
4624 else
4630 -- Report a simple error: if the designated object is a local task,
4631 -- its body has not been seen yet, and its activation will fail an
4632 -- elaboration check.
4639 then
4644 -- Ada 2012 (AI05-0111-3): Detect an attempt to allocate a task or a
4645 -- type with a task component on a subpool. This action must raise
4646 -- Program_Error at runtime.
4652 then
4663 ---------------------------
4664 -- Resolve_Arithmetic_Op --
4665 ---------------------------
4667 -- Used for resolving all arithmetic operators except exponentiation
4678 -- We do the resolution using the base type, because intermediate values
4679 -- in expressions always are of the base type, not a subtype of it.
4682 -- Returns True if N is in a context that expects "any real type"
4685 -- Return True iff given type is Integer or universal real/integer
4688 -- Choose type of integer literal in fixed-point operation to conform
4689 -- to available fixed-point type. T is the type of the other operand,
4690 -- which is needed to determine the expected type of N.
4693 -- Set operand type to T if universal
4695 -------------------------------
4696 -- Expected_Type_Is_Any_Real --
4697 -------------------------------
4700 begin
4701 -- N is the expression after "delta" in a fixed_point_definition;
4702 -- see RM-3.5.9(6):
4705 N_Decimal_Fixed_Point_Definition,
4707 -- N is one of the bounds in a real_range_specification;
4708 -- see RM-3.5.7(5):
4710 N_Real_Range_Specification,
4712 -- N is the expression of a delta_constraint;
4713 -- see RM-J.3(3):
4715 N_Delta_Constraint);
4718 -----------------------------
4719 -- Is_Integer_Or_Universal --
4720 -----------------------------
4727 begin
4733 else
4739 then
4750 ----------------------------
4751 -- Set_Mixed_Mode_Operand --
4752 ----------------------------
4758 begin
4761 -- A universal integer literal is resolved as standard integer
4762 -- except in the case of a fixed-point result, where we leave it
4763 -- as universal (to be handled by Exp_Fixd later on)
4767 else
4775 then
4776 -- A universal real can appear in a fixed-type context. We resolve
4777 -- the literal with that context, even though this might raise an
4778 -- exception prematurely (the other operand may be zero).
4785 then
4786 -- Integer arg in mixed-mode operation. Resolve with universal
4787 -- type, in case preference rule must be applied.
4793 then
4794 -- Not a mixed-mode operation, resolve with context
4800 -- N may itself be a mixed-mode operation, so use context type
4807 then
4808 -- Must be (fixed * fixed) operation, operand must have one
4809 -- compatible interpretation.
4816 then
4817 -- C * F(X) in a fixed context, where C is a real literal or a
4818 -- fixed-point expression. F must have either a fixed type
4819 -- interpretation or an integer interpretation, but not both.
4826 else
4833 else
4841 -- Reanalyze the literal with the fixed type of the context. If
4842 -- context is Universal_Fixed, we are within a conversion, leave
4843 -- the literal as a universal real because there is no usable
4844 -- fixed type, and the target of the conversion plays no role in
4845 -- the resolution.
4847 declare
4851 begin
4854 else
4860 then
4862 else
4870 else
4875 ----------------------
4876 -- Set_Operand_Type --
4877 ----------------------
4880 begin
4883 then
4888 -- Start of processing for Resolve_Arithmetic_Op
4890 begin
4895 then
4899 -- Special-case for mixed-mode universal expressions or fixed point type
4900 -- operation: each argument is resolved separately. The same treatment
4901 -- is required if one of the operands of a fixed point operation is
4902 -- universal real, since in this case we don't do a conversion to a
4903 -- specific fixed-point type (instead the expander handles the case).
4905 -- Set the type of the node to its universal interpretation because
4906 -- legality checks on an exponentiation operand need the context.
4911 then
4922 or else
4925 then
4930 -- If context is a fixed type and one operand is integer, the other
4931 -- is resolved with the type of the context.
4936 then
4943 then
4947 else
4952 -- Check the rule in RM05-4.5.5(19.1/2) disallowing universal_fixed
4953 -- multiplying operators from being used when the expected type is
4954 -- also universal_fixed. Note that B_Typ will be Universal_Fixed in
4955 -- some cases where the expected type is actually Any_Real;
4956 -- Expected_Type_Is_Any_Real takes care of that case.
4960 then
4964 N_Unchecked_Type_Conversion)
4965 then
4972 else
4975 and then not
4977 N_Unchecked_Type_Conversion)
4978 then
4979 Error_Msg_N
4984 -- The expected type is "any real type" in contexts like
4986 -- type T is delta <universal_fixed-expression> ...
4988 -- in which case we need to set the type to Universal_Real
4989 -- so that static expression evaluation will work properly.
4993 else
5003 then
5008 -- If no previous errors, this is only possible if one operand is
5009 -- overloaded and the context is universal. Resolve as such.
5014 else
5016 and then
5018 then
5022 -- If the context is Universal_Fixed and the operands are also
5023 -- universal fixed, this is an error, unless there is only one
5024 -- applicable fixed_point type (usually Duration).
5032 else
5037 else
5042 -- If one of the arguments was resolved to a non-universal type.
5043 -- label the result of the operation itself with the same type.
5044 -- Do the same for the universal argument, if any.
5056 -- In SPARK, a multiplication or division with operands of fixed point
5057 -- types shall be qualified or explicitly converted to identify the
5058 -- result type.
5063 and then
5065 then
5066 Check_SPARK_Restriction
5070 -- Set overflow and division checking bit
5077 -- Give warning if explicit division by zero
5081 then
5087 or else
5090 then
5091 -- Specialize the warning message according to the operation.
5092 -- The following warnings are for the case
5097 -- For division, we have two cases, for float division
5098 -- of an unconstrained float type, on a machine where
5099 -- Machine_Overflows is false, we don't get an exception
5100 -- at run-time, but rather an infinity or Nan. The Nan
5101 -- case is pretty obscure, so just warn about infinities.
5105 and then not Machine_Overflows_On_Target
5106 then
5107 Error_Msg_N
5111 -- For all other cases, we get a Constraint_Error
5113 else
5114 Apply_Compile_Time_Constraint_Error
5120 Apply_Compile_Time_Constraint_Error
5125 Apply_Compile_Time_Constraint_Error
5129 -- Division by zero can only happen with division, rem,
5130 -- and mod operations.
5136 -- Otherwise just set the flag to check at run time
5138 else
5143 -- If Restriction No_Implicit_Conditionals is active, then it is
5144 -- violated if either operand can be negative for mod, or for rem
5145 -- if both operands can be negative.
5149 then
5150 declare
5157 -- Set if corresponding operand might be negative
5159 begin
5160 Determine_Range
5164 Determine_Range
5168 -- Check if we will be generating conditionals. There are two
5169 -- cases where that can happen, first for REM, the only case
5170 -- is largest negative integer mod -1, where the division can
5171 -- overflow, but we still have to give the right result. The
5172 -- front end generates a test for this annoying case. Here we
5173 -- just test if both operands can be negative (that's what the
5174 -- expander does, so we match its logic here).
5176 -- The second case is mod where either operand can be negative.
5177 -- In this case, the back end has to generate additional tests.
5180 or else
5182 then
5194 ------------------
5195 -- Resolve_Call --
5196 ------------------
5208 function Same_Or_Aliased_Subprograms
5211 -- Returns True if the subprogram entity S is the same as E or else
5212 -- S is an alias of E.
5214 ---------------------------------
5215 -- Same_Or_Aliased_Subprograms --
5216 ---------------------------------
5218 function Same_Or_Aliased_Subprograms
5221 is
5223 begin
5228 -- Start of processing for Resolve_Call
5230 begin
5231 -- The context imposes a unique interpretation with type Typ on a
5232 -- procedure or function call. Find the entity of the subprogram that
5233 -- yields the expected type, and propagate the corresponding formal
5234 -- constraints on the actuals. The caller has established that an
5235 -- interpretation exists, and emitted an error if not unique.
5237 -- First deal with the case of a call to an access-to-subprogram,
5238 -- dereference made explicit in Analyze_Call.
5244 else
5245 -- Find the interpretation whose type (a subprogram type) has a
5246 -- return type that is compatible with the context. Analysis of
5247 -- the node has established that one exists.
5266 -- If the prefix is not an entity, then resolve it
5272 -- For an indirect call, we always invalidate checks, since we do not
5273 -- know whether the subprogram is local or global. Yes we could do
5274 -- better here, e.g. by knowing that there are no local subprograms,
5275 -- but it does not seem worth the effort. Similarly, we kill all
5276 -- knowledge of current constant values.
5278 Kill_Current_Values;
5280 -- If this is a procedure call which is really an entry call, do
5281 -- the conversion of the procedure call to an entry call. Protected
5282 -- operations use the same circuitry because the name in the call
5283 -- can be an arbitrary expression with special resolution rules.
5288 then
5292 -- Kill checks and constant values, as above for indirect case
5293 -- Who knows what happens when another task is activated?
5295 Kill_Current_Values;
5298 -- Normal subprogram call with name established in Resolve
5304 -- Otherwise we must have the case of an overloaded call
5306 else
5309 -- Initialize Nam to prevent warning (we know it will be assigned
5310 -- in the loop below, but the compiler does not know that).
5330 then
5331 -- The prefix is a parameterless function call that returns an access
5332 -- to subprogram. If parameters are present in the current call, add
5333 -- add an explicit dereference. We use the base type here because
5334 -- within an instance these may be subtypes.
5336 -- The dereference is added either in Analyze_Call or here. Should
5337 -- be consolidated ???
5346 -- Check that a call to Current_Task does not occur in an entry body
5349 declare
5352 begin
5354 loop
5357 -- Exclude calls that occur within the default of a formal
5358 -- parameter of the entry, since those are evaluated outside
5359 -- of the body.
5366 then
5368 Error_Msg_NE
5371 Error_Msg_NE
5383 -- Check that a procedure call does not occur in the context of the
5384 -- entry call statement of a conditional or timed entry call. Note that
5385 -- the case of a call to a subprogram renaming of an entry will also be
5386 -- rejected. The test for N not being an N_Entry_Call_Statement is
5387 -- defensive, covering the possibility that the processing of entry
5388 -- calls might reach this point due to later modifications of the code
5389 -- above.
5394 then
5398 -- Ada 2005 (AI-345): If a procedure_call_statement is used
5399 -- for a procedure_or_entry_call, the procedure_name or
5400 -- procedure_prefix of the procedure_call_statement shall denote
5401 -- an entry renamed by a procedure, or (a view of) a primitive
5402 -- subprogram of a limited interface whose first parameter is
5403 -- a controlling parameter.
5408 then
5409 Error_Msg_N
5414 -- Check that this is not a call to a protected procedure or entry from
5415 -- within a protected function.
5419 -- Freeze the subprogram name if not in a spec-expression. Note that
5420 -- we freeze procedure calls as well as function calls. Procedure calls
5421 -- are not frozen according to the rules (RM 13.14(14)) because it is
5422 -- impossible to have a procedure call to a non-frozen procedure in
5423 -- pure Ada, but in the code that we generate in the expander, this
5424 -- rule needs extending because we can generate procedure calls that
5425 -- need freezing.
5427 -- In Ada 2012, expression functions may be called within pre/post
5428 -- conditions of subsequent functions or expression functions. Such
5429 -- calls do not freeze when they appear within generated bodies,
5430 -- (including the body of another expression function) which would
5431 -- place the freeze node in the wrong scope. An expression function
5432 -- is frozen in the usual fashion, by the appearance of a real body,
5433 -- or at the end of a declarative part.
5437 and then
5440 then
5444 -- For a predefined operator, the type of the result is the type imposed
5445 -- by context, except for a predefined operation on universal fixed.
5446 -- Otherwise The type of the call is the type returned by the subprogram
5447 -- being called.
5454 -- If the subprogram returns an array type, and the context requires the
5455 -- component type of that array type, the node is really an indexing of
5456 -- the parameterless call. Resolve as such. A pathological case occurs
5457 -- when the type of the component is an access to the array type. In
5458 -- this case the call is truly ambiguous.
5461 and then
5466 and then
5467 Covers
5470 then
5471 declare
5476 begin
5479 then
5480 Error_Msg_N
5482 else
5485 -- The called entity may be an explicit dereference, in which
5486 -- case there is no entity to set.
5494 or else
5496 and then
5498 then
5501 -- Indexed call to a parameterless function
5503 Index_Node :=
5505 Prefix =>
5509 else
5510 -- An Ada 2005 prefixed call to a primitive operation
5511 -- whose first parameter is the prefix. This prefix was
5512 -- prepended to the parameter list, which is actually a
5513 -- list of indexes. Remove the prefix in order to build
5514 -- the proper indexed component.
5516 Index_Node :=
5518 Prefix =>
5521 Parameter_Associations =>
5522 New_List
5527 -- Preserve the parenthesis count of the node
5531 -- Since we are correcting a node classification error made
5532 -- by the parser, we call Replace rather than Rewrite.
5546 else
5550 -- In the case where the call is to an overloaded subprogram, Analyze
5551 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
5552 -- such a case Normalize_Actuals needs to be called once more to order
5553 -- the actuals correctly. Otherwise the call will have the ordering
5554 -- given by the last overloaded subprogram whether this is the correct
5555 -- one being called or not.
5562 -- In any case, call is fully resolved now. Reset Overload flag, to
5563 -- prevent subsequent overload resolution if node is analyzed again
5568 -- If we are calling the current subprogram from immediately within its
5569 -- body, then that is the case where we can sometimes detect cases of
5570 -- infinite recursion statically. Do not try this in case restriction
5571 -- No_Recursion is in effect anyway, and do it only for source calls.
5576 -- Issue warning for possible infinite recursion in the absence
5577 -- of the No_Recursion restriction.
5582 then
5583 -- Here we detected and flagged an infinite recursion, so we do
5584 -- not need to test the case below for further warnings. Also we
5585 -- are all done if we now have a raise SE node.
5591 -- If call is to immediately containing subprogram, then check for
5592 -- the case of a possible run-time detectable infinite recursion.
5594 else
5598 -- Although in general case, recursion is not statically
5599 -- checkable, the case of calling an immediately containing
5600 -- subprogram is easy to catch.
5604 -- If the recursive call is to a parameterless subprogram,
5605 -- then even if we can't statically detect infinite
5606 -- recursion, this is pretty suspicious, and we output a
5607 -- warning. Furthermore, we will try later to detect some
5608 -- cases here at run time by expanding checking code (see
5609 -- Detect_Infinite_Recursion in package Exp_Ch6).
5611 -- If the recursive call is within a handler, do not emit a
5612 -- warning, because this is a common idiom: loop until input
5613 -- is correct, catch illegal input in handler and restart.
5619 then
5620 -- For the case of a procedure call. We give the message
5621 -- only if the call is the first statement in a sequence
5622 -- of statements, or if all previous statements are
5623 -- simple assignments. This is simply a heuristic to
5624 -- decrease false positives, without losing too many good
5625 -- warnings. The idea is that these previous statements
5626 -- may affect global variables the procedure depends on.
5627 -- We also exclude raise statements, that may arise from
5628 -- constraint checks and are probably unrelated to the
5629 -- intended control flow.
5633 then
5634 declare
5636 begin
5640 N_Assignment_Statement,
5641 N_Raise_Constraint_Error)
5642 then
5651 -- Do not give warning if we are in a conditional context
5653 declare
5655 begin
5661 then
5666 -- Here warning is to be issued
5669 Error_Msg_N
5671 Error_Msg_N
5683 -- Check obsolescent reference to Ada.Characters.Handling subprogram
5687 -- If subprogram name is a predefined operator, it was given in
5688 -- functional notation. Replace call node with operator node, so
5689 -- that actuals can be resolved appropriately.
5697 then
5703 -- Create a transient scope if the resulting type requires it
5705 -- There are several notable exceptions:
5707 -- a) In init procs, the transient scope overhead is not needed, and is
5708 -- even incorrect when the call is a nested initialization call for a
5709 -- component whose expansion may generate adjust calls. However, if the
5710 -- call is some other procedure call within an initialization procedure
5711 -- (for example a call to Create_Task in the init_proc of the task
5712 -- run-time record) a transient scope must be created around this call.
5714 -- b) Enumeration literal pseudo-calls need no transient scope
5716 -- c) Intrinsic subprograms (Unchecked_Conversion and source info
5717 -- functions) do not use the secondary stack even though the return
5718 -- type may be unconstrained.
5720 -- d) Calls to a build-in-place function, since such functions may
5721 -- allocate their result directly in a target object, and cases where
5722 -- the result does get allocated in the secondary stack are checked for
5723 -- within the specialized Exp_Ch6 procedures for expanding those
5724 -- build-in-place calls.
5726 -- e) If the subprogram is marked Inline_Always, then even if it returns
5727 -- an unconstrained type the call does not require use of the secondary
5728 -- stack. However, inlining will only take place if the body to inline
5729 -- is already present. It may not be available if e.g. the subprogram is
5730 -- declared in a child instance.
5732 -- If this is an initialization call for a type whose construction
5733 -- uses the secondary stack, and it is not a nested call to initialize
5734 -- a component, we do need to create a transient scope for it. We
5735 -- check for this by traversing the type in Check_Initialization_Call.
5741 and then not Debug_Flag_Dot_K
5742 then
5749 and then Debug_Flag_Dot_K
5750 then
5756 then
5759 elsif Full_Expander_Active
5762 and then
5764 or else
5766 then
5769 -- If the call appears within the bounds of a loop, it will
5770 -- be rewritten and reanalyzed, nothing left to do here.
5777 and then not Within_Init_Proc
5778 then
5782 -- A protected function cannot be called within the definition of the
5783 -- enclosing protected type.
5788 then
5789 Error_Msg_NE
5793 -- Propagate interpretation to actuals, and add default expressions
5794 -- where needed.
5799 -- Overloaded literals are rewritten as function calls, for purpose of
5800 -- resolution. After resolution, we can replace the call with the
5801 -- literal itself.
5807 -- Avoid validation, since it is a static function call
5813 -- If the subprogram is not global, then kill all saved values and
5814 -- checks. This is a bit conservative, since in many cases we could do
5815 -- better, but it is not worth the effort. Similarly, we kill constant
5816 -- values. However we do not need to do this for internal entities
5817 -- (unless they are inherited user-defined subprograms), since they
5818 -- are not in the business of molesting local values.
5820 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
5821 -- kill all checks and values for calls to global subprograms. This
5822 -- takes care of the case where an access to a local subprogram is
5823 -- taken, and could be passed directly or indirectly and then called
5824 -- from almost any context.
5826 -- Note: we do not do this step till after resolving the actuals. That
5827 -- way we still take advantage of the current value information while
5828 -- scanning the actuals.
5830 -- We suppress killing values if we are processing the nodes associated
5831 -- with N_Freeze_Entity nodes. Otherwise the declaration of a tagged
5832 -- type kills all the values as part of analyzing the code that
5833 -- initializes the dispatch tables.
5837 or else Suppress_Value_Tracking_On_Call
5842 then
5843 Kill_Current_Values;
5846 -- If we are warning about unread OUT parameters, this is the place to
5847 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
5848 -- after the above call to Kill_Current_Values (since that call clears
5849 -- the Last_Assignment field of all local variables).
5854 then
5855 declare
5859 begin
5869 then
5879 -- If the subprogram is a primitive operation, check whether or not
5880 -- it is a correct dispatching call.
5884 then
5889 and then not In_Instance
5890 then
5894 -- If this is a dispatching call, generate the appropriate reference,
5895 -- for better source navigation in GPS.
5899 then
5902 -- Normal case, not a dispatching call: generate a call reference
5904 else
5912 -- Check for violation of restriction No_Specific_Termination_Handlers
5913 -- and warn on a potentially blocking call to Abort_Task.
5917 or else
5919 then
5926 -- A call to Ada.Real_Time.Timing_Events.Set_Handler to set a relative
5927 -- timing event violates restriction No_Relative_Delay (AI-0211). We
5928 -- need to check the second argument to determine whether it is an
5929 -- absolute or relative timing event.
5934 then
5938 -- Issue an error for a call to an eliminated subprogram. This routine
5939 -- will not perform the check if the call appears within a default
5940 -- expression.
5944 -- In formal mode, the primitive operations of a tagged type or type
5945 -- extension do not include functions that return the tagged type.
5951 then
5955 -- Implement rule in 12.5.1 (23.3/2): In an instance, if the actual is
5956 -- class-wide and the call dispatches on result in a context that does
5957 -- not provide a tag, the call raises Program_Error.
5960 and then In_Instance
5965 then
5966 -- Verify that none of the formals are controlling
5968 declare
5972 begin
5993 -- Check the dimensions of the actuals in the call. For function calls,
5994 -- propagate the dimensions from the returned type to N.
5998 -- All done, evaluate call and deal with elaboration issues
6005 -----------------------------
6006 -- Resolve_Case_Expression --
6007 -----------------------------
6012 begin
6023 -------------------------------
6024 -- Resolve_Character_Literal --
6025 -------------------------------
6031 begin
6032 -- Verify that the character does belong to the type of the context
6037 -- Wide_Wide_Character literals must always be defined, since the set
6038 -- of wide wide character literals is complete, i.e. if a character
6039 -- literal is accepted by the parser, then it is OK for wide wide
6040 -- character (out of range character literals are rejected).
6045 -- Always accept character literal for type Any_Character, which
6046 -- occurs in error situations and in comparisons of literals, both
6047 -- of which should accept all literals.
6052 -- For Standard.Character or a type derived from it, check that the
6053 -- literal is in range.
6060 -- For Standard.Wide_Character or a type derived from it, check that the
6061 -- literal is in range.
6068 -- For Standard.Wide_Wide_Character or a type derived from it, we
6069 -- know the literal is in range, since the parser checked!
6074 -- If the entity is already set, this has already been resolved in a
6075 -- generic context, or comes from expansion. Nothing else to do.
6080 -- Otherwise we have a user defined character type, and we can use the
6081 -- standard visibility mechanisms to locate the referenced entity.
6083 else
6096 -- If we fall through, then the literal does not match any of the
6097 -- entries of the enumeration type. This isn't just a constraint error
6098 -- situation, it is an illegality (see RM 4.2).
6100 Error_Msg_NE
6104 ---------------------------
6105 -- Resolve_Comparison_Op --
6106 ---------------------------
6108 -- Context requires a boolean type, and plays no role in resolution.
6109 -- Processing identical to that for equality operators. The result type is
6110 -- the base type, which matters when pathological subtypes of booleans with
6111 -- limited ranges are used.
6118 begin
6119 -- If this is an intrinsic operation which is not predefined, use the
6120 -- types of its declared arguments to resolve the possibly overloaded
6121 -- operands. Otherwise the operands are unambiguous and specify the
6122 -- expected type.
6127 else
6138 -- Skip remaining processing if already set to Any_Type
6144 -- Deal with other error cases
6148 T = Any_Character
6149 then
6152 else
6160 -- Resolve the operands if types OK
6169 -- In SPARK, ordering operators <, <=, >, >= are not defined for Boolean
6170 -- types or array types except String.
6173 Check_SPARK_Restriction
6178 then
6179 Check_SPARK_Restriction
6183 -- Check comparison on unordered enumeration
6189 -- Evaluate the relation (note we do this after the above check since
6190 -- this Eval call may change N to True/False.
6196 -----------------------------------------
6197 -- Resolve_Discrete_Subtype_Indication --
6198 -----------------------------------------
6200 procedure Resolve_Discrete_Subtype_Indication
6203 is
6207 begin
6215 else
6225 Error_Msg_NE
6228 -- Rewrite the constraint as a range of Typ
6229 -- to allow compilation to proceed further.
6241 else
6245 -- Additionally, we must check that the bounds are compatible
6246 -- with the given subtype, which might be different from the
6247 -- type of the context.
6251 -- ??? If the above check statically detects a Constraint_Error
6252 -- it replaces the offending bound(s) of the range R with a
6253 -- Constraint_Error node. When the itype which uses these bounds
6254 -- is frozen the resulting call to Duplicate_Subexpr generates
6255 -- a new temporary for the bounds.
6257 -- Unfortunately there are other itypes that are also made depend
6258 -- on these bounds, so when Duplicate_Subexpr is called they get
6259 -- a forward reference to the newly created temporaries and Gigi
6260 -- aborts on such forward references. This is probably sign of a
6261 -- more fundamental problem somewhere else in either the order of
6262 -- itype freezing or the way certain itypes are constructed.
6264 -- To get around this problem we call Remove_Side_Effects right
6265 -- away if either bounds of R are a Constraint_Error.
6267 declare
6271 begin
6287 -------------------------
6288 -- Resolve_Entity_Name --
6289 -------------------------
6291 -- Used to resolve identifiers and expanded names
6296 begin
6297 -- If garbage from errors, set to Any_Type and return
6304 -- Replace named numbers by corresponding literals. Note that this is
6305 -- the one case where Resolve_Entity_Name must reset the Etype, since
6306 -- it is currently marked as universal.
6316 -- For enumeration literals, we need to make sure that a proper style
6317 -- check is done, since such literals are overloaded, and thus we did
6318 -- not do a style check during the first phase of analysis.
6324 -- Case of subtype name appearing as an operand in expression
6328 -- Allow use of subtype if it is a concurrent type where we are
6329 -- currently inside the body. This will eventually be expanded into a
6330 -- call to Self (for tasks) or _object (for protected objects). Any
6331 -- other use of a subtype is invalid.
6335 then
6338 -- Any other use is an error
6340 else
6341 Error_Msg_N
6345 -- Check discriminant use if entity is discriminant in current scope,
6346 -- i.e. discriminant of record or concurrent type currently being
6347 -- analyzed. Uses in corresponding body are unrestricted.
6352 then
6355 -- A parameterless generic function cannot appear in a context that
6356 -- requires resolution.
6367 then
6370 -- In all other cases, just do the possible static evaluation
6372 else
6373 -- A deferred constant that appears in an expression must have a
6374 -- completion, unless it has been removed by in-place expansion of
6375 -- an aggregate.
6381 and then not In_Spec_Expression
6383 then
6387 then
6389 else
6390 Error_Msg_N (
6399 -------------------
6400 -- Resolve_Entry --
6401 -------------------
6413 -- If the bounds of the entry family being called depend on task
6414 -- discriminants, build a new index subtype where a discriminant is
6415 -- replaced with the value of the discriminant of the target task.
6416 -- The target task is the prefix of the entry name in the call.
6418 -----------------------
6419 -- Actual_Index_Type --
6420 -----------------------
6430 -- If the bound is given by a discriminant, replace with a reference
6431 -- to the discriminant of the same name in the target task. If the
6432 -- entry name is the target of a requeue statement and the entry is
6433 -- in the current protected object, the bound to be used is the
6434 -- discriminal of the object (see Apply_Range_Checks for details of
6435 -- the transformation).
6437 -----------------------------
6438 -- Actual_Discriminant_Ref --
6439 -----------------------------
6445 begin
6450 then
6456 then
6457 -- Note: here Bound denotes a discriminant of the corresponding
6458 -- record type tskV, whose discriminal is a formal of the
6459 -- init-proc tskVIP. What we want is the body discriminal,
6460 -- which is associated to the discriminant of the original
6461 -- concurrent type tsk.
6463 return New_Occurrence_Of
6466 else
6467 Ref :=
6477 -- Start of processing for Actual_Index_Type
6479 begin
6482 then
6485 else
6499 -- Start of processing of Resolve_Entry
6501 begin
6502 -- Find name of entry being called, and resolve prefix of name with its
6503 -- own type. The prefix can be overloaded, and the name and signature of
6504 -- the entry must be taken into account.
6508 -- Case of dealing with entry family within the current tasks
6512 else
6518 -- Entry call to an entry (or entry family) in the current task. This
6519 -- is legal even though the task will deadlock. Rewrite as call to
6520 -- current task.
6522 -- This can also be a call to an entry in an enclosing task. If this
6523 -- is a single task, we have to retrieve its name, because the scope
6524 -- of the entry is the task type, not the object. If the enclosing
6525 -- task is a task type, the identity of the task is given by its own
6526 -- self variable.
6528 -- Finally this can be a requeue on an entry of the same task or
6529 -- protected object.
6536 then
6537 -- S is an enclosing task or protected object. The concurrent
6538 -- declaration has been converted into a type declaration, and
6539 -- the object itself has an object declaration that follows
6540 -- the type in the same declarative part.
6552 -- Call to current task. Will be transformed into call to Self
6559 New_N :=
6562 Selector_Name =>
6569 then
6570 -- Use the entry name (which must be unique at this point) to find
6571 -- the prefix that returns the corresponding task/protected type.
6573 declare
6579 begin
6601 -- Up to this point the expression could have been the actual in a
6602 -- simple entry call, and be given by a named association.
6606 else
6612 ------------------------
6613 -- Resolve_Entry_Call --
6614 ------------------------
6626 begin
6627 -- We kill all checks here, because it does not seem worth the effort to
6628 -- do anything better, an entry call is a big operation.
6630 Kill_All_Checks;
6632 -- Processing of the name is similar for entry calls and protected
6633 -- operation calls. Once the entity is determined, we can complete
6634 -- the resolution of the actuals.
6636 -- The selector may be overloaded, in the case of a protected object
6637 -- with overloaded functions. The type of the context is used for
6638 -- resolution.
6643 then
6644 declare
6648 begin
6667 -- Simple entry call
6675 -- Call to member of entry family
6682 -- We cannot in general check the maximum depth of protected entry calls
6683 -- at compile time. But we can tell that any protected entry call at all
6684 -- violates a specified nesting depth of zero.
6690 -- Use context type to disambiguate a protected function that can be
6691 -- called without actuals and that returns an array type, and where the
6692 -- argument list may be an indexing of the returned value.
6697 and then
6703 and then
6704 Covers
6707 then
6708 declare
6711 begin
6712 Index_Node :=
6714 Prefix =>
6718 -- Since we are correcting a node classification error made by the
6719 -- parser, we call Replace rather than Rewrite.
6732 then
6733 -- Rewrite as call to the precondition wrapper, adding the task
6734 -- object to the list of actuals. If the call is to a member of an
6735 -- entry family, include the index as well.
6737 declare
6741 begin
6750 New_Call :=
6752 Name =>
6761 -- The operation name may have been overloaded. Order the actuals
6762 -- according to the formals of the resolved entity, and set the return
6763 -- type to that of the operation.
6774 -- Create a call reference to the entry
6782 -- Verify that a procedure call cannot masquerade as an entry
6783 -- call where an entry call is expected.
6788 then
6793 then
6798 then
6803 -- After resolution, entry calls and protected procedure calls are
6804 -- changed into entry calls, for expansion. The structure of the node
6805 -- does not change, so it can safely be done in place. Protected
6806 -- function calls must keep their structure because they are
6807 -- subexpressions.
6811 -- A protected operation that is not a function may modify the
6812 -- corresponding object, and cannot apply to a constant. If this
6813 -- is an internal call, the prefix is the type itself.
6819 then
6820 Error_Msg_N
6822 Entry_Name);
6836 -- Protected functions can return on the secondary stack, in which
6837 -- case we must trigger the transient scope mechanism.
6839 elsif Full_Expander_Active
6841 then
6846 -------------------------
6847 -- Resolve_Equality_Op --
6848 -------------------------
6850 -- Both arguments must have the same type, and the boolean context does
6851 -- not participate in the resolution. The first pass verifies that the
6852 -- interpretation is not ambiguous, and the type of the left argument is
6853 -- correctly set, or is Any_Type in case of ambiguity. If both arguments
6854 -- are strings or aggregates, allocators, or Null, they are ambiguous even
6855 -- though they carry a single (universal) type. Diagnose this case here.
6863 -- The resolution rule for if expressions requires that each such must
6864 -- have a unique type. This means that if several dependent expressions
6865 -- are of a non-null anonymous access type, and the context does not
6866 -- impose an expected type (as can be the case in an equality operation)
6867 -- the expression must be rejected.
6870 -- Attempt to explain the nature of a redundant comparison with True. If
6871 -- the expression N is too complex, this routine issues a general error
6872 -- message.
6875 -- In the case of allocators and access attributes, the context must
6876 -- provide an indication of the specific access type to be used. If
6877 -- one operand is of such a "generic" access type, check whether there
6878 -- is a specific visible access type that has the same designated type.
6879 -- This is semantically dubious, and of no interest to any real code,
6880 -- but c48008a makes it all worthwhile.
6882 -------------------------
6883 -- Check_If_Expression --
6884 -------------------------
6890 begin
6897 then
6903 ------------------------
6904 -- Explain_Redundancy --
6905 ------------------------
6912 begin
6915 -- Strip the operand down to an entity
6917 loop
6920 else
6925 -- The construct denotes an entity
6930 -- Do not generate an error message when the comparison is done
6931 -- against the enumeration literal Standard.True.
6935 -- Build a customized error message
6962 -- The construct is too complex to disect, issue a general message
6964 else
6969 -----------------------------
6970 -- Find_Unique_Access_Type --
6971 -----------------------------
6978 begin
6980 E_Access_Attribute_Type)
6981 then
6985 E_Access_Attribute_Type)
6986 then
6988 else
7000 then
7013 -- Start of processing for Resolve_Equality_Op
7015 begin
7026 T = Any_Character
7027 then
7030 else
7039 then
7048 -- If expressions must have a single type, and if the context does
7049 -- not impose one the dependent expressions cannot be anonymous
7050 -- access types.
7052 -- Why no similar processing for case expressions???
7056 E_Anonymous_Access_Subprogram_Type)
7058 E_Anonymous_Access_Subprogram_Type)
7059 then
7067 -- In SPARK, equality operators = and /= for array types other than
7068 -- String are only defined when, for each index position, the
7069 -- operands have equal static bounds.
7073 -- Protect call to Matching_Static_Array_Bounds to avoid costly
7074 -- operation if not needed.
7082 then
7083 Check_SPARK_Restriction
7088 -- If the unique type is a class-wide type then it will be expanded
7089 -- into a dispatching call to the predefined primitive. Therefore we
7090 -- check here for potential violation of such restriction.
7096 if Warn_On_Redundant_Constructs
7101 then
7102 Error_Msg_N -- CODEFIX
7112 -- If this is an inequality, it may be the implicit inequality
7113 -- created for a user-defined operation, in which case the corres-
7114 -- ponding equality operation is not intrinsic, and the operation
7115 -- cannot be constant-folded. Else fold.
7120 or else Is_Intrinsic_Subprogram
7122 then
7128 then
7132 -- Ada 2005: If one operand is an anonymous access type, convert the
7133 -- other operand to it, to ensure that the underlying types match in
7134 -- the back-end. Same for access_to_subprogram, and the conversion
7135 -- verifies that the types are subtype conformant.
7137 -- We apply the same conversion in the case one of the operands is a
7138 -- private subtype of the type of the other.
7140 -- Why the Expander_Active test here ???
7142 if Full_Expander_Active
7143 and then
7145 E_Anonymous_Access_Subprogram_Type)
7147 then
7167 ----------------------------------
7168 -- Resolve_Explicit_Dereference --
7169 ----------------------------------
7177 -- The candidate prefix type, if overloaded
7182 begin
7188 -- Use the context type to select the prefix that has the correct
7189 -- designated type. Keep the first match, which will be the inner-
7190 -- most.
7197 then
7202 -- Remove access types that do not match, but preserve access
7203 -- to subprogram interpretations, in case a further dereference
7204 -- is needed (see below).
7217 else
7218 -- If no interpretation covers the designated type of the prefix,
7219 -- this is the pathological case where not all implementations of
7220 -- the prefix allow the interpretation of the node as a call. Now
7221 -- that the expected type is known, Remove other interpretations
7222 -- from prefix, rewrite it as a call, and resolve again, so that
7223 -- the proper call node is generated.
7234 New_N :=
7236 Name =>
7247 -- If not overloaded, resolve P with its own type
7249 else
7257 -- If the designated type is a packed unconstrained array type, and the
7258 -- explicit dereference is not in the context of an attribute reference,
7259 -- then we must compute and set the actual subtype, since it is needed
7260 -- by Gigi. The reason we exclude the attribute case is that this is
7261 -- handled fine by Gigi, and in fact we use such attributes to build the
7262 -- actual subtype. We also exclude generated code (which builds actual
7263 -- subtypes directly if they are needed).
7270 then
7274 -- Note: No Eval processing is required for an explicit dereference,
7275 -- because such a name can never be static.
7279 -------------------------------------
7280 -- Resolve_Expression_With_Actions --
7281 -------------------------------------
7284 begin
7287 -- If N has no actions, and its expression has been constant folded,
7288 -- then rewrite N as just its expression. Note, we can't do this in
7289 -- the general case of Is_Empty_List (Actions (N)) as this would cause
7290 -- Expression (N) to be expanded again.
7294 then
7299 ---------------------------
7300 -- Resolve_If_Expression --
7301 ---------------------------
7310 begin
7315 -- When the "then" expression is of a scalar subtype different from the
7316 -- result subtype, then insert a conversion to ensure the generation of
7317 -- a constraint check. The same is done for the else part below, again
7318 -- comparing subtypes rather than base types.
7322 then
7327 -- If ELSE expression present, just resolve using the determined type
7335 then
7340 -- If no ELSE expression is present, root type must be Standard.Boolean
7341 -- and we provide a Standard.True result converted to the appropriate
7342 -- Boolean type (in case it is a derived boolean type).
7345 Else_Expr :=
7350 else
7359 -------------------------------
7360 -- Resolve_Indexed_Component --
7361 -------------------------------
7369 begin
7372 -- Use the context type to select the prefix that yields the correct
7373 -- component type.
7375 declare
7382 begin
7389 and then
7390 Covers
7393 then
7402 else
7408 else
7419 else
7426 -- If prefix is access type, dereference to get real array type.
7427 -- Note: we do not apply an access check because the expander always
7428 -- introduces an explicit dereference, and the check will happen there.
7434 -- If name was overloaded, set component type correctly now
7435 -- If a misplaced call to an entry family (which has no index types)
7436 -- return. Error will be diagnosed from calling context.
7440 else
7447 -- The prefix may have resolved to a string literal, in which case its
7448 -- etype has a special representation. This is only possible currently
7449 -- if the prefix is a static concatenation, written in functional
7450 -- notation.
7455 else
7462 else
7473 -- Do not generate the warning on suspicious index if we are analyzing
7474 -- package Ada.Tags; otherwise we will report the warning with the
7475 -- Prims_Ptr field of the dispatch table.
7478 or else not
7480 Ada_Tags)
7481 then
7486 -- If the array type is atomic, and is packed, and we are in a left side
7487 -- context, then this is worth a warning, since we have a situation
7488 -- where the access to the component may cause extra read/writes of
7489 -- the atomic array object, which could be considered unexpected.
7497 then
7505 -----------------------------
7506 -- Resolve_Integer_Literal --
7507 -----------------------------
7510 begin
7515 --------------------------------
7516 -- Resolve_Intrinsic_Operator --
7517 --------------------------------
7527 -- If the operand is a literal, it cannot be the expression in a
7528 -- conversion. Use a qualified expression instead.
7533 begin
7535 Res :=
7541 else
7548 -- Start of processing for Resolve_Intrinsic_Operator
7550 begin
7551 -- We must preserve the original entity in a generic setting, so that
7552 -- the legality of the operation can be verified in an instance.
7567 -- If the result or operand types are private, rewrite with unchecked
7568 -- conversions on the operands and the result, to expose the proper
7569 -- underlying numeric type.
7574 then
7576 -- Unchecked_Convert_To (Btyp, Left_Opnd (N));
7577 -- What on earth is this commented out fragment of code???
7581 else
7602 then
7603 -- Add explicit conversion where needed, and save interpretations in
7604 -- case operands are overloaded. If the context is a VMS operation,
7605 -- assert that the conversion is legal (the operands have the proper
7606 -- types to select the VMS intrinsic). Note that in rare cases the
7607 -- VMS operators may be visible, but the default System is being used
7608 -- and Address is a private type.
7619 else
7629 else
7639 else
7644 --------------------------------------
7645 -- Resolve_Intrinsic_Unary_Operator --
7646 --------------------------------------
7648 procedure Resolve_Intrinsic_Unary_Operator
7651 is
7656 begin
7675 else
7680 ------------------------
7681 -- Resolve_Logical_Op --
7682 ------------------------
7687 begin
7690 -- Predefined operations on scalar types yield the base type. On the
7691 -- other hand, logical operations on arrays yield the type of the
7692 -- arguments (and the context).
7696 else
7700 -- OK if this is a VMS-specific intrinsic operation
7705 -- The following test is required because the operands of the operation
7706 -- may be literals, in which case the resulting type appears to be
7707 -- compatible with a signed integer type, when in fact it is compatible
7708 -- only with modular types. If the context itself is universal, the
7709 -- operation is illegal.
7717 Error_Msg_N
7725 then
7729 -- Replace AND by AND THEN, or OR by OR ELSE, if Short_Circuit_And_Or
7730 -- is active and the result type is standard Boolean (do not mess with
7731 -- ops that return a nonstandard Boolean type, because something strange
7732 -- is going on).
7734 -- Note: you might expect this replacement to be done during expansion,
7735 -- but that doesn't work, because when the pragma Short_Circuit_And_Or
7736 -- is used, no part of the right operand of an "and" or "or" operator
7737 -- should be executed if the left operand would short-circuit the
7738 -- evaluation of the corresponding "and then" or "or else". If we left
7739 -- the replacement to expansion time, then run-time checks associated
7740 -- with such operands would be evaluated unconditionally, due to being
7741 -- before the condition prior to the rewriting as short-circuit forms
7742 -- during expansion.
7744 if Short_Circuit_And_Or
7747 then
7755 -- Case of OR changed to OR ELSE
7757 else
7765 -- Return now, since analysis of the rewritten ops will take care of
7766 -- other reference bookkeeping and expression folding.
7781 -- In SPARK, logical operations AND, OR and XOR for arrays are defined
7782 -- only when both operands have same static lower and higher bounds. Of
7783 -- course the types have to match, so only check if operands are
7784 -- compatible and the node itself has no errors.
7788 then
7789 declare
7793 begin
7794 -- Protect call to Matching_Static_Array_Bounds to avoid costly
7795 -- operation if not needed.
7802 then
7803 Check_SPARK_Restriction
7812 ---------------------------
7813 -- Resolve_Membership_Op --
7814 ---------------------------
7816 -- The context can only be a boolean type, and does not determine the
7817 -- arguments. Arguments should be unambiguous, but the preference rule for
7818 -- universal types applies.
7828 -- Analysis has determined a unique type for the left operand. Use it to
7829 -- resolve the disjuncts.
7831 ----------------------------
7832 -- Resolve_Set_Membership --
7833 ----------------------------
7839 begin
7845 -- Alternative is an expression, a range
7846 -- or a subtype mark.
7850 then
7857 -- Check for duplicates for discrete case
7860 declare
7869 begin
7870 -- Loop checking duplicates. This is quadratic, but giant sets
7871 -- are unlikely in this context so it's a reasonable choice.
7878 N_Character_Literal)
7880 then
7898 -- Start of processing for Resolve_Membership_Op
7900 begin
7906 Resolve_Set_Membership;
7911 and then
7913 or else
7916 then
7919 -- Ada 2005 (AI-251): Support the following case:
7921 -- type I is interface;
7922 -- type T is tagged ...
7924 -- function Test (O : I'Class) is
7925 -- begin
7926 -- return O in T'Class.
7927 -- end Test;
7929 -- In this case we have nothing else to do. The membership test will be
7930 -- done at run time.
7937 then
7939 else
7943 -- If mixed-mode operations are present and operands are all literal,
7944 -- the only interpretation involves Duration, which is probably not
7945 -- the intention of the programmer.
7960 then
7966 else
7975 ------------------
7976 -- Resolve_Null --
7977 ------------------
7982 begin
7983 -- Handle restriction against anonymous null access values This
7984 -- restriction can be turned off using -gnatdj.
7986 -- Ada 2005 (AI-231): Remove restriction
7989 and then not Debug_Flag_J
7992 then
7993 -- In the common case of a call which uses an explicitly null value
7994 -- for an access parameter, give specialized error message.
7997 Error_Msg_N
8000 -- Standard message for all other cases (are there any?)
8002 else
8003 Error_Msg_N
8008 -- Ada 2005 (AI-231): Generate the null-excluding check in case of
8009 -- assignment to a null-excluding object
8014 then
8016 Insert_Action
8021 else
8028 -- In a distributed context, null for a remote access to subprogram may
8029 -- need to be replaced with a special record aggregate. In this case,
8030 -- return after having done the transformation.
8035 then
8039 -- The null literal takes its type from the context
8044 -----------------------
8045 -- Resolve_Op_Concat --
8046 -----------------------
8050 -- We wish to avoid deep recursion, because concatenations are often
8051 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
8052 -- operands nonrecursively until we find something that is not a simple
8053 -- concatenation (A in this case). We resolve that, and then walk back
8054 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
8055 -- to do the rest of the work at each level. The Parent pointers allow
8056 -- us to avoid recursion, and thus avoid running out of memory. See also
8057 -- Sem_Ch4.Analyze_Concatenation, where a similar approach is used.
8062 begin
8063 -- The following code is equivalent to:
8065 -- Resolve_Op_Concat_First (NN, Typ);
8066 -- Resolve_Op_Concat_Arg (N, ...);
8067 -- Resolve_Op_Concat_Rest (N, Typ);
8069 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
8070 -- operand is a concatenation.
8072 -- Walk down left operands
8074 loop
8083 -- Now (given the above example) NN is A&B and Op1 is A
8085 -- First resolve Op1 ...
8089 -- ... then walk NN back up until we reach N (where we started), calling
8090 -- Resolve_Op_Concat_Rest along the way.
8092 loop
8099 Check_SPARK_Restriction
8104 ---------------------------
8105 -- Resolve_Op_Concat_Arg --
8106 ---------------------------
8108 procedure Resolve_Op_Concat_Arg
8113 is
8117 begin
8119 if Is_Comp
8123 then
8125 else
8129 -- If both Array & Array and Array & Component are visible, there is a
8130 -- potential ambiguity that must be reported.
8135 then
8139 -- If the operation is user-defined and not overloaded use its
8140 -- profile. The operation may be a renaming, in which case it has
8141 -- been rewritten, and we want the original profile.
8146 then
8148 Etype
8152 -- Otherwise an aggregate may match both the array type and the
8153 -- component type.
8155 else
8160 else
8164 then
8165 declare
8170 begin
8175 -- Special-case the error message when the overloading is
8176 -- caused by a function that yields an array and can be
8177 -- called without parameters.
8182 Error_Msg_NE
8184 Error_Msg_NE
8188 else
8196 or else
8198 then
8199 Error_Msg_N -- CODEFIX
8217 else
8222 else
8226 -- Concatenation is restricted in SPARK: each operand must be either a
8227 -- string literal, the name of a string constant, a static character or
8228 -- string expression, or another concatenation. Arg cannot be a
8229 -- concatenation here as callers of Resolve_Op_Concat_Arg call it
8230 -- separately on each final operand, past concatenation operations.
8234 Check_SPARK_Restriction
8242 then
8243 Check_SPARK_Restriction
8247 -- Do not issue error on an operand that is neither a character nor a
8248 -- string, as the error is issued in Resolve_Op_Concat.
8250 else
8257 -----------------------------
8258 -- Resolve_Op_Concat_First --
8259 -----------------------------
8266 begin
8267 -- The parser folds an enormous sequence of concatenations of string
8268 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
8269 -- in the right operand. If the expression resolves to a predefined "&"
8270 -- operator, all is well. Otherwise, the parser's folding is wrong, so
8271 -- we give an error. See P_Simple_Expression in Par.Ch4.
8276 then
8291 ----------------------------
8292 -- Resolve_Op_Concat_Rest --
8293 ----------------------------
8299 begin
8308 -- If this is not a static concatenation, but the result is a string
8309 -- type (and not an array of strings) ensure that static string operands
8310 -- have their subtypes properly constructed.
8314 then
8320 ----------------------
8321 -- Resolve_Op_Expon --
8322 ----------------------
8327 begin
8328 -- Catch attempts to do fixed-point exponentiation with universal
8329 -- operands, which is a case where the illegality is not caught during
8330 -- normal operator analysis. This is not done in preanalysis mode
8331 -- since the tree is not fully decorated during preanalysis.
8342 then
8352 then
8359 then
8363 -- We do the resolution using the base type, because intermediate values
8364 -- in expressions are always of the base type, not a subtype of it.
8378 -- Evaluate the exponentiation operator for dimensioned type
8381 else
8385 -- Set overflow checking bit. Much cleverer code needed here eventually
8386 -- and perhaps the Resolve routines should be separated for the various
8387 -- arithmetic operations, since they will need different processing. ???
8396 --------------------
8397 -- Resolve_Op_Not --
8398 --------------------
8404 -- This function determines if the parent node is a boolean operator or
8405 -- operation (comparison op, membership test, or short circuit form) and
8406 -- the not in question is the left operand of this operation. Note that
8407 -- if the not is in parens, then false is returned.
8409 -----------------------
8410 -- Parent_Is_Boolean --
8411 -----------------------
8414 begin
8418 else
8420 when N_Op_And |
8421 N_Op_Eq |
8422 N_Op_Ge |
8423 N_Op_Gt |
8424 N_Op_Le |
8425 N_Op_Lt |
8426 N_Op_Ne |
8427 N_Op_Or |
8428 N_Op_Xor |
8429 N_In |
8430 N_Not_In |
8431 N_And_Then |
8432 N_Or_Else =>
8442 -- Start of processing for Resolve_Op_Not
8444 begin
8445 -- Predefined operations on scalar types yield the base type. On the
8446 -- other hand, logical operations on arrays yield the type of the
8447 -- arguments (and the context).
8451 else
8458 -- Straightforward case of incorrect arguments
8465 -- Special case of probable missing parens
8469 Error_Msg_N
8472 else
8473 Error_Msg_N
8480 -- OK resolution of NOT
8482 else
8483 -- Warn if non-boolean types involved. This is a case like not a < b
8484 -- where a and b are modular, where we will get (not a) < b and most
8485 -- likely not (a < b) was intended.
8487 if Warn_On_Questionable_Missing_Parens
8489 and then Parent_Is_Boolean
8490 then
8494 -- Warn on double negation if checking redundant constructs
8496 if Warn_On_Redundant_Constructs
8501 then
8505 -- Complete resolution and evaluation of NOT
8515 -----------------------------
8516 -- Resolve_Operator_Symbol --
8517 -----------------------------
8519 -- Nothing to be done, all resolved already
8525 begin
8529 ----------------------------------
8530 -- Resolve_Qualified_Expression --
8531 ----------------------------------
8539 begin
8542 -- Protect call to Matching_Static_Array_Bounds to avoid costly
8543 -- operation if not needed.
8550 then
8551 Check_SPARK_Restriction
8555 -- A qualified expression requires an exact match of the type, class-
8556 -- wide matching is not allowed. However, if the qualifying type is
8557 -- specific and the expression has a class-wide type, it may still be
8558 -- okay, since it can be the result of the expansion of a call to a
8559 -- dispatching function, so we also have to check class-wideness of the
8560 -- type of the expression's original node.
8563 or else
8567 then
8571 -- If the target type is unconstrained, then we reset the type of the
8572 -- result from the type of the expression. For other cases, the actual
8573 -- subtype of the expression is the target type.
8577 then
8585 -------------------
8586 -- Resolve_Range --
8587 -------------------
8594 -- Returns True if N is of the form X'First .. X'Last where X is the
8595 -- same entity for both attributes.
8597 --------------------
8598 -- First_Last_Ref --
8599 --------------------
8605 begin
8610 then
8611 declare
8614 begin
8618 then
8627 -- Start of processing for Resolve_Range
8629 begin
8634 -- Check for inappropriate range on unordered enumeration type
8638 -- Exclude X'First .. X'Last if X is the same entity for both
8640 and then not First_Last_Ref
8641 then
8648 -- We have to check the bounds for being within the base range as
8649 -- required for a non-static context. Normally this is automatic and
8650 -- done as part of evaluating expressions, but the N_Range node is an
8651 -- exception, since in GNAT we consider this node to be a subexpression,
8652 -- even though in Ada it is not. The circuit in Sem_Eval could check for
8653 -- this, but that would put the test on the main evaluation path for
8654 -- expressions.
8659 -- Check for an ambiguous range over character literals. This will
8660 -- happen with a membership test involving only literals.
8668 -- If bounds are static, constant-fold them, so size computations are
8669 -- identical between front-end and back-end. Do not perform this
8670 -- transformation while analyzing generic units, as type information
8671 -- would be lost when reanalyzing the constant node in the instance.
8684 --------------------------
8685 -- Resolve_Real_Literal --
8686 --------------------------
8691 begin
8692 -- Special processing for fixed-point literals to make sure that the
8693 -- value is an exact multiple of small where this is required. We skip
8694 -- this for the universal real case, and also for generic types.
8700 then
8701 declare
8708 begin
8709 -- Case of literal is not an exact multiple of the Small
8713 -- For a source program literal for a decimal fixed-point type,
8714 -- this is statically illegal (RM 4.9(36)).
8719 then
8723 -- Generate a warning if literal from source
8726 and then Warn_On_Bad_Fixed_Value
8727 then
8728 Error_Msg_N
8730 N);
8733 -- Replace literal by a value that is the exact representation
8734 -- of a value of the type, i.e. a multiple of the small value,
8735 -- by truncation, since Machine_Rounds is false for all GNAT
8736 -- fixed-point types (RM 4.9(38)).
8746 -- In all cases, set the corresponding integer field
8752 -- Now replace the actual type by the expected type as usual
8758 -----------------------
8759 -- Resolve_Reference --
8760 -----------------------
8765 begin
8766 -- Replace general access with specific type
8774 -- If we are taking the reference of a volatile entity, then treat it as
8775 -- a potential modification of this entity. This is too conservative,
8776 -- but necessary because remove side effects can cause transformations
8777 -- of normal assignments into reference sequences that otherwise fail to
8778 -- notice the modification.
8785 --------------------------------
8786 -- Resolve_Selected_Component --
8787 --------------------------------
8802 -- Check whether this is the initialization of a component within an
8803 -- init proc (by assignment or call to another init proc). If true,
8804 -- there is no need for a discriminant check.
8806 --------------------
8807 -- Init_Component --
8808 --------------------
8811 begin
8812 return Inside_Init_Proc
8818 -- Start of processing for Resolve_Selected_Component
8820 begin
8823 -- Use the context type to select the prefix that has a selector
8824 -- of the correct name and type.
8832 else
8836 -- Locate selected component. For a private prefix the selector
8837 -- can denote a discriminant.
8841 -- The visible components of a class-wide type are those of
8842 -- the root type.
8852 then
8859 else
8863 Error_Msg_N
8868 else
8871 -- There may be an implicit dereference. Retrieve
8872 -- designated record type.
8876 else
8882 -- Resolution chooses the new interpretation.
8883 -- Find the component with the right name.
8888 loop
8909 else
8910 -- Resolve prefix with its type
8915 -- Generate cross-reference. We needed to wait until full overloading
8916 -- resolution was complete to do this, since otherwise we can't tell if
8917 -- we are an lvalue or not.
8921 else
8925 -- If prefix is an access type, the node will be transformed into an
8926 -- explicit dereference during expansion. The type of the node is the
8927 -- designated type of that of the prefix.
8932 else
8941 and then not Init_Component
8942 then
8950 -- If the prefix is a record conversion, this may be a renamed
8951 -- discriminant whose bounds differ from those of the original
8952 -- one, so we must ensure that a range check is performed.
8957 then
8961 -- Note: No Eval processing is required, because the prefix is of a
8962 -- record type, or protected type, and neither can possibly be static.
8964 -- If the array type is atomic, and is packed, and we are in a left side
8965 -- context, then this is worth a warning, since we have a situation
8966 -- where the access to the component may cause extra read/writes of the
8967 -- atomic array object, which could be considered unexpected.
8975 then
8976 Error_Msg_N
8978 Error_Msg_N
8985 -------------------
8986 -- Resolve_Shift --
8987 -------------------
8994 begin
8995 -- We do the resolution using the base type, because intermediate values
8996 -- in expressions always are of the base type, not a subtype of it.
9009 ---------------------------
9010 -- Resolve_Short_Circuit --
9011 ---------------------------
9018 begin
9019 -- Ensure all actions associated with the left operand (e.g.
9020 -- finalization of transient controlled objects) are fully evaluated
9021 -- locally within an expression with actions. This is particularly
9022 -- helpful for coverage analysis. However this should not happen in
9023 -- generics.
9026 declare
9028 begin
9036 -- Set Comes_From_Source on L to preserve warnings for unset
9037 -- reference.
9046 -- Check for issuing warning for always False assert/check, this happens
9047 -- when assertions are turned off, in which case the pragma Assert/Check
9048 -- was transformed into:
9050 -- if False and then <condition> then ...
9052 -- and we detect this pattern
9054 if Warn_On_Assertion_Failure
9061 then
9062 declare
9065 begin
9066 -- Special handling of Asssert pragma
9070 then
9071 declare
9073 Original_Node
9074 (Expression
9077 begin
9078 -- Don't warn if original condition is explicit False,
9079 -- since obviously the failure is expected in this case.
9083 then
9086 -- Issue warning. We do not want the deletion of the
9087 -- IF/AND-THEN to take this message with it. We achieve this
9088 -- by making sure that the expanded code points to the Sloc
9089 -- of the expression, not the original pragma.
9091 else
9092 -- Note: Use Error_Msg_F here rather than Error_Msg_N.
9093 -- The source location of the expression is not usually
9094 -- the best choice here. For example, it gets located on
9095 -- the last AND keyword in a chain of boolean expressiond
9096 -- AND'ed together. It is best to put the message on the
9097 -- first character of the assertion, which is the effect
9098 -- of the First_Node call here.
9100 Error_Msg_F
9102 Expression
9107 -- Similar processing for Check pragma
9111 then
9112 -- Don't want to warn if original condition is explicit False
9114 declare
9116 Original_Node
9117 (Expression
9119 begin
9122 then
9125 -- Post warning
9127 else
9128 -- Again use Error_Msg_F rather than Error_Msg_N, see
9129 -- comment above for an explanation of why we do this.
9131 Error_Msg_F
9133 Expression
9141 -- Continue with processing of short circuit
9150 -------------------
9151 -- Resolve_Slice --
9152 -------------------
9160 begin
9163 -- Use the context type to select the prefix that yields the correct
9164 -- array type.
9166 declare
9173 begin
9181 then
9189 else
9194 else
9205 else
9215 -- If the prefix is an access to an unconstrained array, we must use
9216 -- the actual subtype of the object to perform the index checks. The
9217 -- object denoted by the prefix is implicit in the node, so we build
9218 -- an explicit representation for it in order to compute the actual
9219 -- subtype.
9224 declare
9228 begin
9239 then
9242 -- If the name is a selected component that depends on discriminants,
9243 -- build an actual subtype for it. This can happen only when the name
9244 -- itself is overloaded; otherwise the actual subtype is created when
9245 -- the selected component is analyzed.
9248 and then Full_Analysis
9250 then
9251 declare
9254 begin
9259 -- Maybe this should just be "else", instead of checking for the
9260 -- specific case of slice??? This is needed for the case where the
9261 -- prefix is an Image attribute, which gets expanded to a slice, and so
9262 -- has a constrained subtype which we want to use for the slice range
9263 -- check applied below (the range check won't get done if the
9264 -- unconstrained subtype of the 'Image is used).
9270 -- If name was overloaded, set slice type correctly now
9274 -- If the range is specified by a subtype mark, no resolution is
9275 -- necessary. Else resolve the bounds, and apply needed checks.
9280 else
9288 -- Ensure that side effects in the bounds are properly handled
9293 -- Do not apply the range check to nodes associated with the
9294 -- frontend expansion of the dispatch table. We first check
9295 -- if Ada.Tags is already loaded to avoid the addition of an
9296 -- undesired dependence on such run-time unit.
9298 if not Tagged_Type_Expansion
9299 or else not
9305 then
9313 -- Check bad use of type with predicates
9316 Bad_Predicated_Subtype_Use
9320 -- Otherwise here is where we check suspicious indexes
9331 ----------------------------
9332 -- Resolve_String_Literal --
9333 ----------------------------
9344 begin
9345 -- For a string appearing in a concatenation, defer creation of the
9346 -- string_literal_subtype until the end of the resolution of the
9347 -- concatenation, because the literal may be constant-folded away. This
9348 -- is a useful optimization for long concatenation expressions.
9350 -- If the string is an aggregate built for a single character (which
9351 -- happens in a non-static context) or a is null string to which special
9352 -- checks may apply, we build the subtype. Wide strings must also get a
9353 -- string subtype if they come from a one character aggregate. Strings
9354 -- generated by attributes might be static, but it is often hard to
9355 -- determine whether the enclosing context is static, so we generate
9356 -- subtypes for them as well, thus losing some rarer optimizations ???
9357 -- Same for strings that come from a static conversion.
9359 Need_Check :=
9368 -- If the resolving type is itself a string literal subtype, we can just
9369 -- reuse it, since there is no point in creating another.
9375 and then not Need_Check
9377 N_Attribute_Reference,
9378 N_Qualified_Expression,
9379 N_Type_Conversion)
9380 then
9383 -- Otherwise we must create a string literal subtype. Note that the
9384 -- whole idea of string literal subtypes is simply to avoid the need
9385 -- for building a full fledged array subtype for each literal.
9387 else
9393 or else Need_Check
9394 then
9401 then
9407 -- The validity of a null string has been checked in the call to
9408 -- Eval_String_Literal.
9413 -- Always accept string literal with component type Any_Character, which
9414 -- occurs in error situations and in comparisons of literals, both of
9415 -- which should accept all literals.
9420 -- If the type is bit-packed, then we always transform the string
9421 -- literal into a full fledged aggregate.
9426 -- Deal with cases of Wide_Wide_String, Wide_String, and String
9428 else
9429 -- For Standard.Wide_Wide_String, or any other type whose component
9430 -- type is Standard.Wide_Wide_Character, we know that all the
9431 -- characters in the string must be acceptable, since the parser
9432 -- accepted the characters as valid character literals.
9437 -- For the case of Standard.String, or any other type whose component
9438 -- type is Standard.Character, we must make sure that there are no
9439 -- wide characters in the string, i.e. that it is entirely composed
9440 -- of characters in range of type Character.
9442 -- If the string literal is the result of a static concatenation, the
9443 -- test has already been performed on the components, and need not be
9444 -- repeated.
9448 then
9452 -- If we are out of range, post error. This is one of the
9453 -- very few places that we place the flag in the middle of
9454 -- a token, right under the offending wide character. Not
9455 -- quite clear if this is right wrt wide character encoding
9456 -- sequences, but it's only an error message!
9458 Error_Msg
9465 -- For the case of Standard.Wide_String, or any other type whose
9466 -- component type is Standard.Wide_Character, we must make sure that
9467 -- there are no wide characters in the string, i.e. that it is
9468 -- entirely composed of characters in range of type Wide_Character.
9470 -- If the string literal is the result of a static concatenation,
9471 -- the test has already been performed on the components, and need
9472 -- not be repeated.
9476 then
9480 -- If we are out of range, post error. This is one of the
9481 -- very few places that we place the flag in the middle of
9482 -- a token, right under the offending wide character.
9484 -- This is not quite right, because characters in general
9485 -- will take more than one character position ???
9487 Error_Msg
9494 -- If the root type is not a standard character, then we will convert
9495 -- the string into an aggregate and will let the aggregate code do
9496 -- the checking. Standard Wide_Wide_Character is also OK here.
9498 else
9502 -- See if the component type of the array corresponding to the string
9503 -- has compile time known bounds. If yes we can directly check
9504 -- whether the evaluation of the string will raise constraint error.
9505 -- Otherwise we need to transform the string literal into the
9506 -- corresponding character aggregate and let the aggregate code do
9507 -- the checking.
9511 -- Check for the case of full range, where we are definitely OK
9517 -- Here the range is not the complete base type range, so check
9519 declare
9527 begin
9530 then
9536 then
9537 Apply_Compile_Time_Constraint_Error
9539 CE_Range_Check_Failed,
9550 -- If we got here we meed to transform the string literal into the
9551 -- equivalent qualified positional array aggregate. This is rather
9552 -- heavy artillery for this situation, but it is hard work to avoid.
9554 declare
9559 begin
9560 -- Build the character literals, we give them source locations that
9561 -- correspond to the string positions, which is a bit tricky given
9562 -- the possible presence of wide character escape sequences.
9576 -- Should we have a call to Skip_Wide here ???
9578 -- ??? else
9579 -- Skip_Wide (P);
9587 Expression =>
9594 -----------------------------
9595 -- Resolve_Subprogram_Info --
9596 -----------------------------
9599 begin
9603 -----------------------------
9604 -- Resolve_Type_Conversion --
9605 -----------------------------
9617 -- Set to False to suppress cases where we want to suppress the test
9618 -- for redundancy to avoid possible false positives on this warning.
9620 begin
9621 if not Conv_OK
9623 then
9627 -- If the Operand Etype is Universal_Fixed, then the conversion is
9628 -- never redundant. We need this check because by the time we have
9629 -- finished the rather complex transformation, the conversion looks
9630 -- redundant when it is not.
9635 -- If the operand is marked as Any_Fixed, then special processing is
9636 -- required. This is also a case where we suppress the test for a
9637 -- redundant conversion, since most certainly it is not redundant.
9642 -- Mixed-mode operation involving a literal. Context must be a fixed
9643 -- type which is applied to the literal subsequently.
9651 or else
9653 then
9654 -- Return if expression is ambiguous
9659 -- If nothing else, the available fixed type is Duration
9661 else
9665 -- Resolve the real operand with largest available precision
9669 else
9675 -- If the operand is a literal (it could be a non-static and
9676 -- illegal exponentiation) check whether the use of Duration
9677 -- is potentially inaccurate.
9682 then
9683 Error_Msg_N
9686 Error_Msg_N
9693 then
9696 else
9705 -- In SPARK, a type conversion between array types should be restricted
9706 -- to types which have matching static bounds.
9708 -- Protect call to Matching_Static_Array_Bounds to avoid costly
9709 -- operation if not needed.
9716 then
9717 Check_SPARK_Restriction
9721 -- In formal mode, the operand of an ancestor type conversion must be an
9722 -- object (not an expression).
9730 then
9736 -- Note: we do the Eval_Type_Conversion call before applying the
9737 -- required checks for a subtype conversion. This is important, since
9738 -- both are prepared under certain circumstances to change the type
9739 -- conversion to a constraint error node, but in the case of
9740 -- Eval_Type_Conversion this may reflect an illegality in the static
9741 -- case, and we would miss the illegality (getting only a warning
9742 -- message), if we applied the type conversion checks first.
9746 -- Even when evaluation is not possible, we may be able to simplify the
9747 -- conversion or its expression. This needs to be done before applying
9748 -- checks, since otherwise the checks may use the original expression
9749 -- and defeat the simplifications. This is specifically the case for
9750 -- elimination of the floating-point Truncation attribute in
9751 -- float-to-int conversions.
9755 -- If after evaluation we still have a type conversion, then we may need
9756 -- to apply checks required for a subtype conversion.
9758 -- Skip these type conversion checks if universal fixed operands
9759 -- operands involved, since range checks are handled separately for
9760 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
9766 then
9770 -- Issue warning for conversion of simple object to its own type. We
9771 -- have to test the original nodes, since they may have been rewritten
9772 -- by various optimizations.
9776 -- Here we test for a redundant conversion if the warning mode is
9777 -- active (and was not locally reset), and we have a type conversion
9778 -- from source not appearing in a generic instance.
9780 if Test_Redundant
9783 and then not In_Instance
9784 then
9788 -- If the node is part of a larger expression, the Target_Type
9789 -- may not be the original type of the node if the context is a
9790 -- condition. Recover original type to see if conversion is needed.
9794 then
9798 -- If we have an entity name, then give the warning if the entity
9799 -- is the right type, or if it is a loop parameter covered by the
9800 -- original type (that's needed because loop parameters have an
9801 -- odd subtype coming from the bounds).
9804 and then
9806 or else
9810 -- If not an entity, then type of expression must match
9813 then
9814 -- One more check, do not give warning if the analyzed conversion
9815 -- has an expression with non-static bounds, and the bounds of the
9816 -- target are static. This avoids junk warnings in cases where the
9817 -- conversion is necessary to establish staticness, for example in
9818 -- a case statement.
9822 then
9825 -- Finally, if this type conversion occurs in a context requiring
9826 -- a prefix, and the expression is a qualified expression then the
9827 -- type conversion is not redundant, since a qualified expression
9828 -- is not a prefix, whereas a type conversion is. For example, "X
9829 -- := T'(Funx(...)).Y;" is illegal because a selected component
9830 -- requires a prefix, but a type conversion makes it legal: "X :=
9831 -- T(T'(Funx(...))).Y;"
9833 -- In Ada 2012, a qualified expression is a name, so this idiom is
9834 -- no longer needed, but we still suppress the warning because it
9835 -- seems unfriendly for warnings to pop up when you switch to the
9836 -- newer language version.
9840 N_Indexed_Component,
9841 N_Selected_Component,
9842 N_Slice,
9843 N_Explicit_Dereference)
9844 then
9847 -- Never warn on conversion to Long_Long_Integer'Base since
9848 -- that is most likely an artifact of the extended overflow
9849 -- checking and comes from complex expanded code.
9854 -- Here we give the redundant conversion warning. If it is an
9855 -- entity, give the name of the entity in the message. If not,
9856 -- just mention the expression.
9858 -- Shoudn't we test Warn_On_Redundant_Constructs here ???
9860 else
9863 Error_Msg_NE -- CODEFIX
9866 else
9867 Error_Msg_NE
9875 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
9876 -- No need to perform any interface conversion if the type of the
9877 -- expression coincides with the target type.
9880 and then Full_Expander_Active
9882 then
9883 declare
9887 begin
9899 -- Conversion from interface type
9903 -- Ada 2005 (AI-217): Handle entities from limited views
9907 Error_Msg_NE -- CODEFIX
9910 Error_Msg_N
9912 N);
9915 and then not
9918 then
9920 Error_Msg_NE -- CODEFIX
9923 Error_Msg_N
9925 N);
9927 else
9931 -- Conversion to interface type
9935 -- Handle subtypes
9942 or else Interface_Present_In_Ancestor
9945 then
9947 else
9950 Error_Msg_N
9958 -- Ada 2012: if target type has predicates, the result requires a
9959 -- predicate check. If the context is a call to another predicate
9960 -- check we must prevent infinite recursion.
9966 or else
9968 then
9971 else
9977 ----------------------
9978 -- Resolve_Unary_Op --
9979 ----------------------
9988 begin
9991 Check_SPARK_Restriction
9995 -- Deal with intrinsic unary operators
10001 then
10006 -- Deal with universal cases
10009 or else
10011 then
10018 -- Generate warning for expressions like abs (x mod 2)
10020 if Warn_On_Redundant_Constructs
10022 then
10026 Error_Msg_N -- CODEFIX
10031 -- Deal with reference generation
10038 -- Set overflow checking bit. Much cleverer code needed here eventually
10039 -- and perhaps the Resolve routines should be separated for the various
10040 -- arithmetic operations, since they will need different processing ???
10048 -- Generate warning for expressions like -5 mod 3 for integers. No need
10049 -- to worry in the floating-point case, since parens do not affect the
10050 -- result so there is no point in giving in a warning.
10052 declare
10061 begin
10062 if Warn_On_Questionable_Missing_Parens
10066 then
10069 -- We are looking for cases where the right operand is not
10070 -- parenthesized, and is a binary operator, multiply, divide, or
10071 -- mod. These are the cases where the grouping can affect results.
10075 then
10076 -- For mod, we always give the warning, since the value is
10077 -- affected by the parenthesization (e.g. (-5) mod 315 /=
10078 -- -(5 mod 315)). But for the other cases, the only concern is
10079 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
10080 -- overflows, but (-2) * 64 does not). So we try to give the
10081 -- message only when overflow is possible.
10085 then
10090 else
10096 else
10100 -- Note that the test below is deliberately excluding the
10101 -- largest negative number, since that is a potentially
10102 -- troublesome case (e.g. -2 * x, where the result is the
10103 -- largest negative integer has an overflow with 2 * x).
10110 -- For the multiplication case, the only case we have to worry
10111 -- about is when (-a)*b is exactly the largest negative number
10112 -- so that -(a*b) can cause overflow. This can only happen if
10113 -- a is a power of 2, and more generally if any operand is a
10114 -- constant that is not a power of 2, then the parentheses
10115 -- cannot affect whether overflow occurs. We only bother to
10116 -- test the left most operand
10118 -- Loop looking at left operands for one that has known value
10125 -- Operand value of 0 or 1 skips warning
10130 -- Otherwise check power of 2, if power of 2, warn, if
10131 -- anything else, skip warning.
10133 else
10137 else
10146 -- Keep looking at left operands
10151 -- For rem or "/" we can only have a problematic situation
10152 -- if the divisor has a value of minus one or one. Otherwise
10153 -- overflow is impossible (divisor > 1) or we have a case of
10154 -- division by zero in any case.
10159 then
10163 -- If we fall through warning should be issued
10165 -- Shouldn't we test Warn_On_Questionable_Missing_Parens ???
10167 Error_Msg_N
10174 ----------------------------------
10175 -- Resolve_Unchecked_Expression --
10176 ----------------------------------
10178 procedure Resolve_Unchecked_Expression
10181 is
10182 begin
10187 ---------------------------------------
10188 -- Resolve_Unchecked_Type_Conversion --
10189 ---------------------------------------
10191 procedure Resolve_Unchecked_Type_Conversion
10194 is
10200 begin
10201 -- Resolve operand using its own type
10208 ------------------------------
10209 -- Rewrite_Operator_As_Call --
10210 ------------------------------
10217 begin
10224 New_N :=
10235 ------------------------------
10236 -- Rewrite_Renamed_Operator --
10237 ------------------------------
10239 procedure Rewrite_Renamed_Operator
10243 is
10248 begin
10249 -- Rewrite the operator node using the real operator, not its renaming.
10250 -- Exclude user-defined intrinsic operations of the same name, which are
10251 -- treated separately and rewritten as calls.
10260 -- Indicate that both the original entity and its renaming are
10261 -- referenced at this point.
10272 -- If the context type is private, add the appropriate conversions so
10273 -- that the operator is applied to the full view. This is done in the
10274 -- routines that resolve intrinsic operators.
10278 then
10280 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
10281 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
10294 -- Operator renames a user-defined operator of the same name. Use the
10295 -- original operator in the node, which is the one Gigi knows about.
10302 -----------------------
10303 -- Set_Slice_Subtype --
10304 -----------------------
10306 -- Build an implicit subtype declaration to represent the type delivered by
10307 -- the slice. This is an abbreviated version of an array subtype. We define
10308 -- an index subtype for the slice, using either the subtype name or the
10309 -- discrete range of the slice. To be consistent with index usage elsewhere
10310 -- we create a list header to hold the single index. This list is not
10311 -- otherwise attached to the syntax tree.
10322 begin
10326 else
10327 -- We force the evaluation of a range. This is definitely needed in
10328 -- the renamed case, and seems safer to do unconditionally. Note in
10329 -- any case that since we will create and insert an Itype referring
10330 -- to this range, we must make sure any side effect removal actions
10331 -- are inserted before the Itype definition.
10342 -- Take a new copy of Drange (where bounds have been rewritten to
10343 -- reference side-effect-free names). Using a separate tree ensures
10344 -- that further expansion (e.g. while rewriting a slice assignment
10345 -- into a FOR loop) does not attempt to remove side effects on the
10346 -- bounds again (which would cause the bounds in the index subtype
10347 -- definition to refer to temporaries before they are defined) (the
10348 -- reason is that some names are considered side effect free here
10349 -- for the subtype, but not in the context of a loop iteration
10350 -- scheme).
10371 -- The Etype of the existing Slice node is reset to this slice subtype.
10372 -- Its bounds are obtained from its first index.
10376 -- For packed slice subtypes, freeze immediately (except in the case of
10377 -- being in a "spec expression" where we never freeze when we first see
10378 -- the expression).
10383 -- For all other cases insert an itype reference in the slice's actions
10384 -- so that the itype is frozen at the proper place in the tree (i.e. at
10385 -- the point where actions for the slice are analyzed). Note that this
10386 -- is different from freezing the itype immediately, which might be
10387 -- premature (e.g. if the slice is within a transient scope). This needs
10388 -- to be done only if expansion is enabled.
10395 --------------------------------
10396 -- Set_String_Literal_Subtype --
10397 --------------------------------
10405 begin
10417 -- The low bound is set from the low bound of the corresponding index
10418 -- type. Note that we do not store the high bound in the string literal
10419 -- subtype, but it can be deduced if necessary from the length and the
10420 -- low bound.
10425 -- If the lower bound is not static we create a range for the string
10426 -- literal, using the index type and the known length of the literal.
10427 -- The index type is not necessarily Positive, so the upper bound is
10428 -- computed as T'Val (T'Pos (Low_Bound) + L - 1).
10430 else
10431 declare
10437 Prefix =>
10441 Left_Opnd =>
10444 Prefix =>
10446 Expressions =>
10448 Right_Opnd =>
10457 begin
10459 Set_String_Literal_Low_Bound
10462 else
10463 -- If the index type is an enumeration type, build bounds
10464 -- expression with attributes.
10466 Set_String_Literal_Low_Bound
10470 Prefix =>
10477 -- Build bona fide subtype for the string, and wrap it in an
10478 -- unchecked conversion, because the backend expects the
10479 -- String_Literal_Subtype to have a static lower bound.
10481 Index_Subtype :=
10488 -- In the context, the Index_Type may already have a constraint,
10489 -- so use common base type on string subtype. The base type may
10490 -- be used when generating attributes of the string, for example
10491 -- in the context of a slice assignment.
10516 ------------------------------
10517 -- Simplify_Type_Conversion --
10518 ------------------------------
10521 begin
10523 declare
10528 begin
10530 and then
10537 -- Special processing required if the conversion is the expression
10538 -- of a Truncation attribute reference. In this case we replace:
10540 -- ityp (ftyp'Truncation (x))
10542 -- by
10544 -- ityp (x)
10546 -- with the Float_Truncate flag set, which is more efficient.
10548 then
10557 -----------------------------
10558 -- Unique_Fixed_Point_Type --
10559 -----------------------------
10568 -- Give error messages for true ambiguity. Messages are posted on node
10569 -- N, and entities T1, T2 are the possible interpretations.
10571 -----------------------
10572 -- Fixed_Point_Error --
10573 -----------------------
10576 begin
10582 -- Start of processing for Unique_Fixed_Point_Type
10584 begin
10585 -- The operations on Duration are visible, so Duration is always a
10586 -- possible interpretation.
10590 -- Look for fixed-point types in enclosing scopes
10599 then
10601 Fixed_Point_Error;
10603 else
10614 -- Look for visible fixed type declarations in the context
10625 then
10627 Fixed_Point_Error;
10629 else
10642 Error_Msg_NE
10644 else
10645 Error_Msg_NE
10652 ----------------------
10653 -- Valid_Conversion --
10654 ----------------------
10656 function Valid_Conversion
10661 is
10666 function Conversion_Check
10669 -- Little routine to post Msg if Valid is False, returns Valid value
10672 -- If Report_Errs, then calls Errout.Error_Msg_N with its arguments
10674 procedure Conversion_Error_NE
10678 -- If Report_Errs, then calls Errout.Error_Msg_NE with its arguments
10680 function Valid_Tagged_Conversion
10683 -- Specifically test for validity of tagged conversions
10686 -- Check index and component conformance, and accessibility levels if
10687 -- the component types are anonymous access types (Ada 2005).
10689 ----------------------
10690 -- Conversion_Check --
10691 ----------------------
10693 function Conversion_Check
10696 is
10697 begin
10698 if not Valid
10700 -- A generic unit has already been analyzed and we have verified
10701 -- that a particular conversion is OK in that context. Since the
10702 -- instance is reanalyzed without relying on the relationships
10703 -- established during the analysis of the generic, it is possible
10704 -- to end up with inconsistent views of private types. Do not emit
10705 -- the error message in such cases. The rest of the machinery in
10706 -- Valid_Conversion still ensures the proper compatibility of
10707 -- target and operand types.
10709 and then not In_Instance
10710 then
10717 ------------------------
10718 -- Conversion_Error_N --
10719 ------------------------
10722 begin
10728 -------------------------
10729 -- Conversion_Error_NE --
10730 -------------------------
10732 procedure Conversion_Error_NE
10736 is
10737 begin
10743 ----------------------------
10744 -- Valid_Array_Conversion --
10745 ----------------------------
10748 is
10763 begin
10764 -- Error if wrong number of dimensions
10766 if
10768 then
10769 Conversion_Error_N
10773 -- Number of dimensions matches
10775 else
10776 -- Loop through indexes of the two arrays
10784 -- Error if index types are incompatible
10790 then
10791 Conversion_Error_N
10793 Operand);
10801 -- If component types have same base type, all set
10806 -- Here if base types of components are not the same. The only
10807 -- time this is allowed is if we have anonymous access types.
10809 -- The conversion of arrays of anonymous access types can lead
10810 -- to dangling pointers. AI-392 formalizes the accessibility
10811 -- checks that must be applied to such conversions to prevent
10812 -- out-of-scope references.
10814 elsif Ekind_In
10816 E_Anonymous_Access_Subprogram_Type)
10818 and then
10820 then
10823 then
10825 Conversion_Error_N
10828 Conversion_Error_N
10830 Operand);
10837 -- Conversion not allowed because of accessibility levels
10839 else
10840 Conversion_Error_N
10846 else
10850 -- All other cases where component base types do not match
10852 else
10853 Conversion_Error_N
10855 Operand);
10859 -- Check that component subtypes statically match. For numeric
10860 -- types this means that both must be either constrained or
10861 -- unconstrained. For enumeration types the bounds must match.
10862 -- All of this is checked in Subtypes_Statically_Match.
10864 if not Subtypes_Statically_Match
10866 then
10867 Conversion_Error_N
10876 -----------------------------
10877 -- Valid_Tagged_Conversion --
10878 -----------------------------
10880 function Valid_Tagged_Conversion
10883 is
10884 begin
10885 -- Upward conversions are allowed (RM 4.6(22))
10889 then
10892 -- Downward conversion are allowed if the operand is class-wide
10893 -- (RM 4.6(23)).
10897 then
10902 then
10903 return
10907 -- Ada 2005 (AI-251): The conversion to/from interface types is
10908 -- always valid
10913 -- If the operand is a class-wide type obtained through a limited_
10914 -- with clause, and the context includes the non-limited view, use
10915 -- it to determine whether the conversion is legal.
10921 then
10926 then
10929 else
10930 Conversion_Error_NE
10937 -- Start of processing for Valid_Conversion
10939 begin
10943 declare
10951 begin
10952 -- Remove procedure calls, which syntactically cannot appear in
10953 -- this context, but which cannot be removed by type checking,
10954 -- because the context does not impose a type.
10956 -- When compiling for VMS, spurious ambiguities can be produced
10957 -- when arithmetic operations have a literal operand and return
10958 -- System.Address or a descendant of it. These ambiguities are
10959 -- otherwise resolved by the context, but for conversions there
10960 -- is no context type and the removal of the spurious operations
10961 -- must be done explicitly here.
10963 -- The node may be labelled overloaded, but still contain only one
10964 -- interpretation because others were discarded earlier. If this
10965 -- is the case, retain the single interpretation if legal.
10973 then
10974 -- More than one candidate interpretation is available
10984 then
11009 Conversion_Error_N
11012 -- If the interpretation involves a standard operator, use
11013 -- the location of the type, which may be user-defined.
11017 else
11021 Conversion_Error_N -- CODEFIX
11026 else
11030 Conversion_Error_N -- CODEFIX
11042 -- If we are within a child unit, check whether the type of the
11043 -- expression has an ancestor in a parent unit, in which case it
11044 -- belongs to its derivation class even if the ancestor is private.
11045 -- See RM 7.3.1 (5.2/3).
11049 -- Numeric types
11053 -- A universal fixed expression can be converted to any numeric type
11058 -- Also no need to check when in an instance or inlined body, because
11059 -- the legality has been established when the template was analyzed.
11060 -- Furthermore, numeric conversions may occur where only a private
11061 -- view of the operand type is visible at the instantiation point.
11062 -- This results in a spurious error if we check that the operand type
11063 -- is a numeric type.
11065 -- Note: in a previous version of this unit, the following tests were
11066 -- applied only for generated code (Comes_From_Source set to False),
11067 -- but in fact the test is required for source code as well, since
11068 -- this situation can arise in source code.
11073 -- Otherwise we need the conversion check
11075 else
11076 return Conversion_Check
11078 or else
11084 -- Array types
11090 then
11091 Conversion_Error_N
11095 else
11099 -- Ada 2005 (AI-251): Anonymous access types where target references an
11100 -- interface type.
11103 E_Anonymous_Access_Type)
11105 then
11106 -- Check the static accessibility rule of 4.6(17). Note that the
11107 -- check is not enforced when within an instance body, since the
11108 -- RM requires such cases to be caught at run time.
11110 -- If the operand is a rewriting of an allocator no check is needed
11111 -- because there are no accessibility issues.
11119 then
11120 -- In an instance, this is a run-time check, but one we know
11121 -- will fail, so generate an appropriate warning. The raise
11122 -- will be generated by Expand_N_Type_Conversion.
11125 Conversion_Error_N
11127 Operand);
11128 Conversion_Error_N
11131 else
11132 Conversion_Error_N
11134 Operand);
11138 -- Special accessibility checks are needed in the case of access
11139 -- discriminants declared for a limited type.
11143 then
11144 -- When the operand is a selected access discriminant the check
11145 -- needs to be made against the level of the object denoted by
11146 -- the prefix of the selected name (Object_Access_Level handles
11147 -- checking the prefix of the operand for this case).
11152 then
11153 -- In an instance, this is a run-time check, but one we know
11154 -- will fail, so generate an appropriate warning. The raise
11155 -- will be generated by Expand_N_Type_Conversion.
11158 Conversion_Error_N
11161 Conversion_Error_N
11163 Operand);
11164 else
11165 Conversion_Error_N
11172 -- The case of a reference to an access discriminant from
11173 -- within a limited type declaration (which will appear as
11174 -- a discriminal) is always illegal because the level of the
11175 -- discriminant is considered to be deeper than any (nameable)
11176 -- access type.
11180 and then
11183 then
11184 Conversion_Error_N
11186 Operand);
11194 -- General and anonymous access types
11197 E_Anonymous_Access_Type)
11198 and then
11199 Conversion_Check
11201 and then not
11203 E_Access_Protected_Subprogram_Type),
11205 then
11208 then
11209 Conversion_Error_N
11214 -- Check the static accessibility rule of 4.6(17). Note that the
11215 -- check is not enforced when within an instance body, since the RM
11216 -- requires such cases to be caught at run time.
11221 N_Object_Declaration
11222 then
11223 -- Ada 2012 (AI05-0149): Perform legality checking on implicit
11224 -- conversions from an anonymous access type to a named general
11225 -- access type. Such conversions are not allowed in the case of
11226 -- access parameters and stand-alone objects of an anonymous
11227 -- access type. The implicit conversion case is recognized by
11228 -- testing that Comes_From_Source is False and that it's been
11229 -- rewritten. The Comes_From_Source test isn't sufficient because
11230 -- nodes in inlined calls to predefined library routines can have
11231 -- Comes_From_Source set to False. (Is there a better way to test
11232 -- for implicit conversions???)
11239 then
11242 -- Implicit conversions aren't allowed for objects of an
11243 -- anonymous access type, since such objects have nonstatic
11244 -- levels in Ada 2012.
11247 N_Object_Declaration
11248 then
11249 Conversion_Error_N
11254 -- Implicit conversions aren't allowed for anonymous access
11255 -- parameters. The "not Is_Local_Anonymous_Access_Type" test
11256 -- is done to exclude anonymous access results.
11260 N_Function_Specification,
11261 N_Procedure_Specification)
11262 then
11263 Conversion_Error_N
11268 -- This is a case where there's an enclosing object whose
11269 -- to which the "statically deeper than" relationship does
11270 -- not apply (such as an access discriminant selected from
11271 -- a dereference of an access parameter).
11275 then
11276 Conversion_Error_N
11281 -- In other cases, the level of the operand's type must be
11282 -- statically less deep than that of the target type, else
11283 -- implicit conversion is disallowed (by RM12-8.6(27.1/3)).
11287 then
11288 Conversion_Error_N
11297 then
11298 -- In an instance, this is a run-time check, but one we know
11299 -- will fail, so generate an appropriate warning. The raise
11300 -- will be generated by Expand_N_Type_Conversion.
11303 Conversion_Error_N
11305 Operand);
11306 Conversion_Error_N
11309 else
11310 -- Avoid generation of spurious error message
11313 Conversion_Error_N
11315 Operand);
11321 -- Special accessibility checks are needed in the case of access
11322 -- discriminants declared for a limited type.
11326 then
11327 -- When the operand is a selected access discriminant the check
11328 -- needs to be made against the level of the object denoted by
11329 -- the prefix of the selected name (Object_Access_Level handles
11330 -- checking the prefix of the operand for this case).
11335 then
11336 -- In an instance, this is a run-time check, but one we know
11337 -- will fail, so generate an appropriate warning. The raise
11338 -- will be generated by Expand_N_Type_Conversion.
11341 Conversion_Error_N
11344 Conversion_Error_N
11346 Operand);
11348 else
11349 Conversion_Error_N
11356 -- The case of a reference to an access discriminant from
11357 -- within a limited type declaration (which will appear as
11358 -- a discriminal) is always illegal because the level of the
11359 -- discriminant is considered to be deeper than any (nameable)
11360 -- access type.
11363 and then
11366 then
11367 Conversion_Error_N
11369 Operand);
11375 -- In the presence of limited_with clauses we have to use non-limited
11376 -- views, if available.
11380 -- Helper function to handle limited views
11382 --------------------------
11383 -- Full_Designated_Type --
11384 --------------------------
11389 begin
11390 -- Handle the limited view of a type
11395 then
11397 else
11402 -- Local Declarations
11410 -- Start of processing for Check_Limited
11412 begin
11416 else
11418 Conversion_Error_NE
11423 -- Ada 2005 AI-384: legality rule is symmetric in both
11424 -- designated types. The conversion is legal (with possible
11425 -- constraint check) if either designated type is
11426 -- unconstrained.
11429 or else
11431 and then
11434 then
11435 -- Special case, if Value_Size has been used to make the
11436 -- sizes different, the conversion is not allowed even
11437 -- though the subtypes statically match.
11442 then
11443 Conversion_Error_NE
11446 Conversion_Error_NE
11451 -- Normal case where conversion is allowed
11453 else
11457 else
11458 Error_Msg_NE
11466 -- Access to subprogram types. If the operand is an access parameter,
11467 -- the type has a deeper accessibility that any master, and cannot be
11468 -- assigned. We must make an exception if the conversion is part of an
11469 -- assignment and the target is the return object of an extended return
11470 -- statement, because in that case the accessibility check takes place
11471 -- after the return.
11475 then
11479 and then
11483 then
11484 Conversion_Error_N
11486 Operand);
11487 Conversion_Error_N
11490 Operand);
11492 Error_Msg_NE
11497 -- Check that the designated types are subtype conformant
11503 -- Check the static accessibility rule of 4.6(20)
11507 then
11508 Conversion_Error_N
11510 Operand);
11512 -- Check that if the operand type is declared in a generic body,
11513 -- then the target type must be declared within that same body
11514 -- (enforces last sentence of 4.6(20)).
11517 declare
11523 begin
11530 Conversion_Error_N
11539 -- Remote subprogram access types
11543 then
11544 -- It is valid to convert from one RAS type to another provided
11545 -- that their specification statically match.
11547 Check_Subtype_Conformant
11550 Old_Id =>
11552 Err_Loc =>
11553 N);
11556 -- If it was legal in the generic, it's legal in the instance
11561 -- If both are tagged types, check legality of view conversions
11564 and then
11566 then
11569 -- Types derived from the same root type are convertible
11574 -- In an instance or an inlined body, there may be inconsistent views of
11575 -- the same type, or of types derived from a common root.
11578 and then
11581 then
11584 -- Special check for common access type error case
11588 then
11590 Conversion_Error_NE -- CODEFIX
11594 else
11595 Conversion_Error_NE