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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S E M _ R E S --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2014, Free Software Foundation, Inc. --
10 -- --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
20 -- --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
23 -- --
24 ------------------------------------------------------------------------------
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
97 -- Enforce the restrictions on the use of discriminants when constraining
98 -- a component of a discriminated type (record or concurrent type).
101 -- Given a node for an operator associated with type T, check that
102 -- the operator is visible. Operators all of whose operands are
103 -- universal must be checked for visibility during resolution
104 -- because their type is not determinable based on their operands.
106 procedure Check_Fully_Declared_Prefix
109 -- Check that the type of the prefix of a dereference is not incomplete
112 -- Given a call node, N, which is known to occur immediately within the
113 -- subprogram being called, determines whether it is a detectable case of
114 -- an infinite recursion, and if so, outputs appropriate messages. Returns
115 -- True if an infinite recursion is detected, and False otherwise.
118 -- If the type of the object being initialized uses the secondary stack
119 -- directly or indirectly, create a transient scope for the call to the
120 -- init proc. This is because we do not create transient scopes for the
121 -- initialization of individual components within the init proc itself.
122 -- Could be optimized away perhaps?
125 -- N is the node for a logical operator. If the operator is predefined, and
126 -- the root type of the operands is Standard.Boolean, then a check is made
127 -- for restriction No_Direct_Boolean_Operators. This procedure also handles
128 -- the style check for Style_Check_Boolean_And_Or.
131 -- Determine whether E is an access type declared by an access declaration,
132 -- and not an (anonymous) allocator type.
135 -- Utility to check whether the entity for an operator is a predefined
136 -- operator, in which case the expression is left as an operator in the
137 -- tree (else it is rewritten into a call). An instance of an intrinsic
138 -- conversion operation may be given an operator name, but is not treated
139 -- like an operator. Note that an operator that is an imported back-end
140 -- builtin has convention Intrinsic, but is expected to be rewritten into
141 -- a call, so such an operator is not treated as predefined by this
142 -- predicate.
145 -- If a default expression in entry call N depends on the discriminants
146 -- of the task, it must be replaced with a reference to the discriminant
147 -- of the task being called.
149 procedure Resolve_Op_Concat_Arg
154 -- Internal procedure for Resolve_Op_Concat to resolve one operand of
155 -- concatenation operator. The operand is either of the array type or of
156 -- the component type. If the operand is an aggregate, and the component
157 -- type is composite, this is ambiguous if component type has aggregates.
160 -- Does the first part of the work of Resolve_Op_Concat
163 -- Does the "rest" of the work of Resolve_Op_Concat, after the left operand
164 -- has been resolved. See Resolve_Op_Concat for details.
202 function Operator_Kind
205 -- Utility to map the name of an operator into the corresponding Node. Used
206 -- by other node rewriting procedures.
209 -- Resolve actuals of call, and add default expressions for missing ones.
210 -- N is the Node_Id for the subprogram call, and Nam is the entity of the
211 -- called subprogram.
214 -- Called from Resolve_Call, when the prefix denotes an entry or element
215 -- of entry family. Actuals are resolved as for subprograms, and the node
216 -- is rebuilt as an entry call. Also called for protected operations. Typ
217 -- is the context type, which is used when the operation is a protected
218 -- function with no arguments, and the return value is indexed.
221 -- A call to a user-defined intrinsic operator is rewritten as a call to
222 -- the corresponding predefined operator, with suitable conversions. Note
223 -- that this applies only for intrinsic operators that denote predefined
224 -- operators, not ones that are intrinsic imports of back-end builtins.
227 -- Ditto, for unary operators (arithmetic ones and "not" on signed
228 -- integer types for VMS).
231 -- If an operator node resolves to a call to a user-defined operator,
232 -- rewrite the node as a function call.
234 procedure Make_Call_Into_Operator
238 -- Inverse transformation: if an operator is given in functional notation,
239 -- then after resolving the node, transform into an operator node, so
240 -- that operands are resolved properly. Recall that predefined operators
241 -- do not have a full signature and special resolution rules apply.
243 procedure Rewrite_Renamed_Operator
247 -- An operator can rename another, e.g. in an instantiation. In that
248 -- case, the proper operator node must be constructed and resolved.
251 -- The String_Literal_Subtype is built for all strings that are not
252 -- operands of a static concatenation operation. If the argument is
253 -- not a N_String_Literal node, then the call has no effect.
256 -- Build subtype of array type, with the range specified by the slice
259 -- Called after N has been resolved and evaluated, but before range checks
260 -- have been applied. Currently simplifies a combination of floating-point
261 -- to integer conversion and Truncation attribute.
264 -- A universal_fixed expression in an universal context is unambiguous if
265 -- there is only one applicable fixed point type. Determining whether there
266 -- is only one requires a search over all visible entities, and happens
267 -- only in very pathological cases (see 6115-006).
269 -------------------------
270 -- Ambiguous_Character --
271 -------------------------
276 begin
280 -- First the ones in Standard
285 -- Include Wide_Wide_Character in Ada 2005 mode
291 -- Now any other types that match
301 -------------------------
302 -- Analyze_And_Resolve --
303 -------------------------
306 begin
312 begin
317 -- Versions with check(s) suppressed
319 procedure Analyze_And_Resolve
323 is
326 begin
328 declare
330 begin
336 else
337 declare
339 begin
347 and then Scope_Is_Transient
348 then
349 -- This can only happen if a transient scope was created for an inner
350 -- expression, which will be removed upon completion of the analysis
351 -- of an enclosing construct. The transient scope must have the
352 -- suppress status of the enclosing environment, not of this Analyze
353 -- call.
356 Scope_Suppress;
360 procedure Analyze_And_Resolve
363 is
366 begin
368 declare
370 begin
376 else
377 declare
379 begin
388 Scope_Suppress;
392 ----------------------------
393 -- Check_Discriminant_Use --
394 ----------------------------
402 begin
403 -- Any use in a spec-expression is legal
410 -- Discriminant cannot be used to constrain a scalar type
417 then
422 -- The following check catches the unusual case where a
423 -- discriminant appears within an index constraint that is part of
424 -- a larger expression within a constraint on a component, e.g. "C
425 -- : Int range 1 .. F (new A(1 .. D))". For now we only check case
426 -- of record components, and note that a similar check should also
427 -- apply in the case of discriminant constraints below. ???
429 -- Note that the check for N_Subtype_Declaration below is to
430 -- detect the valid use of discriminants in the constraints of a
431 -- subtype declaration when this subtype declaration appears
432 -- inside the scope of a record type (which is syntactically
433 -- illegal, but which may be created as part of derived type
434 -- processing for records). See Sem_Ch3.Build_Derived_Record_Type
435 -- for more info.
439 and then not
441 and then
443 N_Subtype_Declaration)
445 then
446 Error_Msg_N
451 -- Detect a common error:
453 -- type R (D : Positive := 100) is record
454 -- Name : String (1 .. D);
455 -- end record;
457 -- The default value causes an object of type R to be allocated
458 -- with room for Positive'Last characters. The RM does not mandate
459 -- the allocation of the maximum size, but that is what GNAT does
460 -- so we should warn the programmer that there is a problem.
469 -- Return True if type T has a large enough range that any
470 -- array whose index type covered the whole range of the type
471 -- would likely raise Storage_Error.
473 ------------------------
474 -- Large_Storage_Type --
475 ------------------------
478 begin
479 -- The type is considered large if its bounds are known at
480 -- compile time and if it requires at least as many bits as
481 -- a Positive to store the possible values.
485 and then
490 -- Start of processing for Check_Large
492 begin
493 -- Check that the Disc has a large range
499 -- If the enclosing type is limited, we allocate only the
500 -- default value, not the maximum, and there is no need for
501 -- a warning.
507 -- Check that it is the high bound
511 then
515 -- Check the array allows a large range at this bound. First
516 -- find the array
530 -- Next, find the dimension
538 loop
547 -- Now, check the dimension has a large range
553 -- Warn about the danger
555 Error_Msg_N
565 -- Legal case is in index or discriminant constraint
568 N_Discriminant_Association)
569 then
571 Error_Msg_N
576 then
577 Error_Msg_N
583 -- Otherwise, context is an expression. It should not be within (i.e. a
584 -- subexpression of) a constraint for a component.
586 else
590 N_Subtype_Indication,
591 N_Entry_Declaration)
592 loop
598 -- If the discriminant is used in an expression that is a bound of a
599 -- scalar type, an Itype is created and the bounds are attached to
600 -- its range, not to the original subtype indication. Such use is of
601 -- course a double fault.
605 N_Derived_Type_Definition)
608 -- The constraint itself may be given by a subtype indication,
609 -- rather than by a more common discrete range.
612 and then
616 then
617 Error_Msg_N
623 --------------------------------
624 -- Check_For_Visible_Operator --
625 --------------------------------
628 begin
630 Error_Msg_NE -- CODEFIX
632 Error_Msg_N -- CODEFIX
637 ----------------------------------
638 -- Check_Fully_Declared_Prefix --
639 ----------------------------------
641 procedure Check_Fully_Declared_Prefix
644 is
645 begin
646 -- Check that the designated type of the prefix of a dereference is
647 -- not an incomplete type. This cannot be done unconditionally, because
648 -- dereferences of private types are legal in default expressions. This
649 -- case is taken care of in Check_Fully_Declared, called below. There
650 -- are also 2005 cases where it is legal for the prefix to be unfrozen.
652 -- This consideration also applies to similar checks for allocators,
653 -- qualified expressions, and type conversions.
655 -- An additional exception concerns other per-object expressions that
656 -- are not directly related to component declarations, in particular
657 -- representation pragmas for tasks. These will be per-object
658 -- expressions if they depend on discriminants or some global entity.
659 -- If the task has access discriminants, the designated type may be
660 -- incomplete at the point the expression is resolved. This resolution
661 -- takes place within the body of the initialization procedure, where
662 -- the discriminant is replaced by its discriminal.
666 then
669 -- Ada 2005 (AI-326): Tagged incomplete types allowed. The wrong usages
670 -- are handled by Analyze_Access_Attribute, Analyze_Assignment,
671 -- Analyze_Object_Renaming, and Freeze_Entity.
677 E_Incomplete_Type
679 then
681 else
686 ------------------------------
687 -- Check_Infinite_Recursion --
688 ------------------------------
695 -- Check whether list of actuals is identical to list of formals of
696 -- called function (which is also the enclosing scope).
698 ------------------------
699 -- Same_Argument_List --
700 ------------------------
707 begin
710 else
719 then
730 -- Start of processing for Check_Infinite_Recursion
732 begin
733 -- Special case, if this is a procedure call and is a call to the
734 -- current procedure with the same argument list, then this is for
735 -- sure an infinite recursion and we insert a call to raise SE.
739 and then Same_Argument_List
740 then
741 declare
743 begin
747 then
759 -- If not that special case, search up tree, quitting if we reach a
760 -- construct (e.g. a conditional) that tells us that this is not a
761 -- case for an infinite recursion warning.
764 loop
767 -- If no parent, then we were not inside a subprogram, this can for
768 -- example happen when processing certain pragmas in a spec. Just
769 -- return False in this case.
775 -- Done if we get to subprogram body, this is definitely an infinite
776 -- recursion case if we did not find anything to stop us.
780 -- If appearing in conditional, result is false
783 N_And_Then,
784 N_Case_Expression,
785 N_Case_Statement,
786 N_If_Expression,
787 N_If_Statement)
788 then
793 then
794 -- If the call is the expression of a return statement and the
795 -- actuals are identical to the formals, it's worth a warning.
796 -- However, we skip this if there is an immediately preceding
797 -- raise statement, since the call is never executed.
799 -- Furthermore, this corresponds to a common idiom:
801 -- function F (L : Thing) return Boolean is
802 -- begin
803 -- raise Program_Error;
804 -- return F (L);
805 -- end F;
807 -- for generating a stub function
810 and then Same_Argument_List
811 then
814 -- OK, return statement is in a statement list, look for raise
816 declare
819 begin
820 -- Skip past N_Freeze_Entity nodes generated by expansion
825 loop
829 -- If no raise statement, give warning. We look at the
830 -- original node, because in the case of "raise ... with
831 -- ...", the node has been transformed into a call.
834 and then
842 else
854 -------------------------------
855 -- Check_Initialization_Call --
856 -------------------------------
862 -- Check whether the creation of an object of the type will involve
863 -- use of the secondary stack. If T is a record type, this is true
864 -- if the expression for some component uses the secondary stack, e.g.
865 -- through a call to a function that returns an unconstrained value.
866 -- False if T is controlled, because cleanups occur elsewhere.
868 -------------
869 -- Uses_SS --
870 -------------
877 begin
878 -- Normally we want to use the underlying type, but if it's not set
879 -- then continue with T.
896 then
897 -- The expression for a dynamic component may be rewritten
898 -- as a dereference, so retrieve original node.
902 -- Return True if the expression is a call to a function
903 -- (including an attribute function such as Image, or a
904 -- user-defined operator) with a result that requires a
905 -- transient scope.
912 then
925 else
930 -- Start of processing for Check_Initialization_Call
932 begin
933 -- Establish a transient scope if the type needs it
940 ---------------------------------------
941 -- Check_No_Direct_Boolean_Operators --
942 ---------------------------------------
945 begin
948 then
949 -- Restriction only applies to original source code
956 -- Do style check (but skip if in instance, error is on template)
965 ------------------------------
966 -- Check_Parameterless_Call --
967 ------------------------------
973 -- If the prefix is of an access_to_subprogram type, the node must be
974 -- rewritten as a call. Ditto if the prefix is overloaded and all its
975 -- interpretations are access to subprograms.
977 ---------------------------
978 -- Prefix_Is_Access_Subp --
979 ---------------------------
985 begin
986 -- If the context is an attribute reference that can apply to
987 -- functions, this is never a parameterless call (RM 4.1.4(6)).
991 Name_Code_Address,
992 Name_Access)
993 then
998 return
1001 else
1006 then
1017 -- Start of processing for Check_Parameterless_Call
1019 begin
1020 -- Defend against junk stuff if errors already detected
1027 then
1034 -- If the context expects a value, and the name is a procedure, this is
1035 -- most likely a missing 'Access. Don't try to resolve the parameterless
1036 -- call, error will be caught when the outer call is analyzed.
1041 and then
1043 N_Function_Call,
1044 N_Procedure_Call_Statement)
1045 then
1049 -- Rewrite as call if overloadable entity that is (or could be, in the
1050 -- overloaded case) a function call. If we know for sure that the entity
1051 -- is an enumeration literal, we do not rewrite it.
1053 -- If the entity is the name of an operator, it cannot be a call because
1054 -- operators cannot have default parameters. In this case, this must be
1055 -- a string whose contents coincide with an operator name. Set the kind
1056 -- of the node appropriately.
1064 -- Rewrite as call if it is an explicit dereference of an expression of
1065 -- a subprogram access type, and the subprogram type is not that of a
1066 -- procedure or entry.
1068 or else
1071 -- Rewrite as call if it is a selected component which is a function,
1072 -- this is the case of a call to a protected function (which may be
1073 -- overloaded with other protected operations).
1075 or else
1078 or else
1080 E_Procedure)
1083 -- If one of the above three conditions is met, rewrite as call. Apply
1084 -- the rewriting only once.
1086 then
1089 then
1091 -- This may be a prefixed call that was not fully analyzed, e.g.
1092 -- an actual in an instance.
1097 then
1107 -- If overloaded, overload set belongs to new copy
1111 -- Change node to parameterless function call (note that the
1112 -- Parameter_Associations associations field is left set to Empty,
1113 -- its normal default value since there are no parameters)
1131 -----------------------------
1132 -- Is_Definite_Access_Type --
1133 -----------------------------
1137 begin
1143 ----------------------
1144 -- Is_Predefined_Op --
1145 ----------------------
1148 begin
1149 -- Predefined operators are intrinsic subprograms
1155 -- A call to a back-end builtin is never a predefined operator
1166 -----------------------------
1167 -- Make_Call_Into_Operator --
1168 -----------------------------
1170 procedure Make_Call_Into_Operator
1174 is
1189 -- If the operand is not universal, and the operator is given by an
1190 -- expanded name, verify that the operand has an interpretation with a
1191 -- type defined in the given scope of the operator.
1194 -- Find a type of the given class in package Pack that contains the
1195 -- operator.
1197 ---------------------------
1198 -- Operand_Type_In_Scope --
1199 ---------------------------
1206 begin
1210 else
1224 ---------------
1225 -- Type_In_P --
1226 ---------------
1232 -- Verify that node is not part of the type declaration for the
1233 -- candidate type, which would otherwise be invisible.
1235 -------------
1236 -- In_Decl --
1237 -------------
1243 begin
1252 else
1255 loop
1258 else
1267 -- Start of processing for Type_In_P
1269 begin
1270 -- If the context type is declared in the prefix package, this is the
1271 -- desired base type.
1276 else
1280 and then not In_Decl
1281 then
1292 -- Start of processing for Make_Call_Into_Operator
1294 begin
1297 -- Binary operator
1307 -- Unary operator
1309 else
1315 -- If the operator is denoted by an expanded name, and the prefix is
1316 -- not Standard, but the operator is a predefined one whose scope is
1317 -- Standard, then this is an implicit_operator, inserted as an
1318 -- interpretation by the procedure of the same name. This procedure
1319 -- overestimates the presence of implicit operators, because it does
1320 -- not examine the type of the operands. Verify now that the operand
1321 -- type appears in the given scope. If right operand is universal,
1322 -- check the other operand. In the case of concatenation, either
1323 -- argument can be the component type, so check the type of the result.
1324 -- If both arguments are literals, look for a type of the right kind
1325 -- defined in the given scope. This elaborate nonsense is brought to
1326 -- you courtesy of b33302a. The type itself must be frozen, so we must
1327 -- find the type of the proper class in the given scope.
1329 -- A final wrinkle is the multiplication operator for fixed point types,
1330 -- which is defined in Standard only, and not in the scope of the
1331 -- fixed point type itself.
1336 -- If this is a package renaming, get renamed entity, which will be
1337 -- the scope of the operands if operaton is type-correct.
1343 -- If the entity being called is defined in the given package, it is
1344 -- a renaming of a predefined operator, and known to be legal.
1348 then
1351 -- Visibility does not need to be checked in an instance: if the
1352 -- operator was not visible in the generic it has been diagnosed
1353 -- already, else there is an implicit copy of it in the instance.
1361 then
1366 -- Ada 2005 AI-420: Predefined equality on Universal_Access is
1367 -- available.
1372 then
1375 else
1384 and then Is_Binary
1386 then
1392 -- Verify that the scope contains a type that corresponds to
1393 -- the given literal. Optimize the case where Pack is Standard.
1415 else
1424 else
1433 then
1436 -- If the type is defined elsewhere, and the operator is not
1437 -- defined in the given scope (by a renaming declaration, e.g.)
1438 -- then this is an error as well. If an extension of System is
1439 -- present, and the type may be defined there, Pack must be
1440 -- System itself.
1447 then
1450 else
1456 then
1463 Error_Msg_NE
1468 -- Detect a mismatch between the context type and the result type
1469 -- in the named package, which is otherwise not detected if the
1470 -- operands are universal. Check is only needed if source entity is
1471 -- an operator, not a function that renames an operator.
1478 and then not In_Instance
1479 then
1482 then
1483 -- Already checked above
1487 -- Operator may be defined in an extension of System
1491 then
1494 else
1495 -- Could we use Wrong_Type here??? (this would require setting
1496 -- Etype (N) to the actual type found where Typ was expected).
1507 else
1511 -- If this is a call to a function that renames a predefined equality,
1512 -- the renaming declaration provides a type that must be used to
1513 -- resolve the operands. This must be done now because resolution of
1514 -- the equality node will not resolve any remaining ambiguity, and it
1515 -- assumes that the first operand is not overloaded.
1520 then
1528 -- Do rewrite setting Comes_From_Source on the result if the original
1529 -- call came from source. Although it is not strictly the case that the
1530 -- operator as such comes from the source, logically it corresponds
1531 -- exactly to the function call in the source, so it should be marked
1532 -- this way (e.g. to make sure that validity checks work fine).
1534 declare
1536 begin
1541 -- If this is an arithmetic operator and the result type is private,
1542 -- the operands and the result must be wrapped in conversion to
1543 -- expose the underlying numeric type and expand the proper checks,
1544 -- e.g. on division.
1548 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
1549 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
1558 else
1562 -- If in ASIS_Mode, propagate operand types to original actuals of
1563 -- function call, which would otherwise not be fully resolved. If
1564 -- the call has already been constant-folded, nothing to do. We
1565 -- relocate the operand nodes rather than copy them, to preserve
1566 -- original_node pointers, given that the operands themselves may
1567 -- have been rewritten.
1575 else
1584 -------------------
1585 -- Operator_Kind --
1586 -------------------
1588 function Operator_Kind
1591 is
1594 begin
1595 -- Use CASE statement or array???
1632 else
1636 -- Unary operators
1638 else
1647 else
1655 ----------------------------
1656 -- Preanalyze_And_Resolve --
1657 ----------------------------
1662 begin
1666 -- Normally, we suppress all checks for this preanalysis. There is no
1667 -- point in processing them now, since they will be applied properly
1668 -- and in the proper location when the default expressions reanalyzed
1669 -- and reexpanded later on. We will also have more information at that
1670 -- point for possible suppression of individual checks.
1672 -- However, in SPARK mode, most expansion is suppressed, and this
1673 -- later reanalysis and reexpansion may not occur. SPARK mode does
1674 -- require the setting of checking flags for proof purposes, so we
1675 -- do the SPARK preanalysis without suppressing checks.
1677 -- This special handling for SPARK mode is required for example in the
1678 -- case of Ada 2012 constructs such as quantified expressions, which are
1679 -- expanded in two separate steps.
1683 else
1687 Expander_Mode_Restore;
1691 -- Version without context type
1696 begin
1703 Expander_Mode_Restore;
1707 ----------------------------------
1708 -- Replace_Actual_Discriminants --
1709 ----------------------------------
1716 -- Comment needed???
1718 -------------------
1719 -- Process_Discr --
1720 -------------------
1725 begin
1731 then
1747 -- Start of processing for Replace_Actual_Discriminants
1749 begin
1763 else
1768 -------------
1769 -- Resolve --
1770 -------------
1786 -- Determine whether a node comes from a predefined library unit or
1787 -- Standard.
1790 -- Try and fix up a literal so that it matches its expected type. New
1791 -- literals are manufactured if necessary to avoid cascaded errors.
1794 -- Return the current scope. Skip loop scopes created for the purpose of
1795 -- quantified expression analysis since those do not appear in the tree.
1798 -- Additional diagnostics when an ambiguous call has an ambiguous
1799 -- argument (typically a controlling actual).
1802 -- Called when attempt at resolving current expression fails
1804 ------------------------------------
1805 -- Comes_From_Predefined_Lib_Unit --
1806 -------------------------------------
1809 begin
1810 return
1812 or else Is_Predefined_File_Name
1816 --------------------
1817 -- Patch_Up_Value --
1818 --------------------
1821 begin
1838 then
1843 Char_Literal_Value =>
1859 --------------------------
1860 -- Proper_Current_Scope --
1861 --------------------------
1866 begin
1869 -- Skip a loop scope created for quantified expression analysis
1873 then
1875 else
1883 -------------------------------
1884 -- Report_Ambiguous_Argument --
1885 -------------------------------
1892 begin
1896 then
1899 -- Could use comments on what is going on here???
1907 else
1916 -----------------------
1917 -- Resolution_Failed --
1918 -----------------------
1921 begin
1927 -- The caller will return without calling the expander, so we need
1928 -- to set the analyzed flag. Note that it is fine to set Analyzed
1929 -- to True even if we are in the middle of a shallow analysis,
1930 -- (see the spec of sem for more details) since this is an error
1931 -- situation anyway, and there is no point in repeating the
1932 -- analysis later (indeed it won't work to repeat it later, since
1933 -- we haven't got a clear resolution of which entity is being
1934 -- referenced.)
1940 -- Start of processing for Resolve
1942 begin
1947 -- Access attribute on remote subprogram cannot be used for a non-remote
1948 -- access-to-subprogram type.
1952 Name_Unrestricted_Access,
1953 Name_Unchecked_Access)
1959 then
1960 Error_Msg_N
1966 -- If the context is a Remote_Access_To_Subprogram, access attributes
1967 -- must be resolved with the corresponding fat pointer. There is no need
1968 -- to check for the attribute name since the return type of an
1969 -- attribute is never a remote type.
1974 then
1975 declare
1983 begin
1984 -- Check that Typ is a remote access-to-subprogram type
1988 -- Prefix (N) must statically denote a remote subprogram
1989 -- declared in a package specification.
1993 Attr = Attribute_Unrestricted_Access
1994 then
2009 or else
2011 then
2013 Error_Msg_N
2015 N);
2018 -- If we are generating code in distributed mode, perform
2019 -- semantic checks against corresponding remote entities.
2021 if Expander_Active
2023 then
2024 Check_Subtype_Conformant
2026 Old_Id => Designated_Type
2052 then
2057 -- Return if already analyzed
2064 -- Any case of Any_Type as the Etype value means that we had a
2065 -- previous error.
2074 -- The resolution of an Expression_With_Actions is determined by
2075 -- its Expression.
2083 -- If not overloaded, then we know the type, and all that needs doing
2084 -- is to check that this type is compatible with the context.
2090 -- In the overloaded case, we must select the interpretation that
2091 -- is compatible with the context (i.e. the type passed to Resolve)
2093 else
2094 -- Loop through possible interpretations
2104 -- We are only interested in interpretations that are compatible
2105 -- with the expected type, any other interpretations are ignored.
2110 Write_Eol;
2113 else
2114 -- Skip the current interpretation if it is disabled by an
2115 -- abstract operator. This action is performed only when the
2116 -- type against which we are resolving is the same as the
2117 -- type of the interpretation.
2124 then
2132 -- First matching interpretation
2140 -- Matching interpretation that is not the first, maybe an
2141 -- error, but there are some cases where preference rules are
2142 -- used to choose between the two possibilities. These and
2143 -- some more obscure cases are handled in Disambiguate.
2145 else
2146 -- If the current statement is part of a predefined library
2147 -- unit, then all interpretations which come from user level
2148 -- packages should not be considered. Check previous and
2149 -- current one.
2157 -- Previous interpretation must be discarded
2167 -- Otherwise apply further disambiguation steps
2172 -- Disambiguation has succeeded. Skip the remaining
2173 -- interpretations.
2183 else
2184 -- Before we issue an ambiguity complaint, check for
2185 -- the case of a subprogram call where at least one
2186 -- of the arguments is Any_Type, and if so, suppress
2187 -- the message, since it is a cascaded error.
2190 declare
2194 begin
2206 Write_Eol;
2219 then
2224 then
2228 -- Not that special case, so issue message using the
2229 -- flag Ambiguous to control printing of the header
2230 -- message only at the start of an ambiguous set.
2235 then
2236 Error_Msg_N
2239 else
2240 Error_Msg_NE -- CODEFIX
2248 Error_Msg_N
2250 else
2251 Error_Msg_N -- CODEFIX
2257 then
2258 Report_Ambiguous_Argument;
2264 -- By default, the error message refers to the candidate
2265 -- interpretation. But if it is a predefined operator, it
2266 -- is implicitly declared at the declaration of the type
2267 -- of the operand. Recover the sloc of that declaration
2268 -- for the error message.
2274 Standard_Standard
2275 then
2280 then
2288 Standard_Standard
2289 then
2294 then
2298 -- If this is an indirect call, use the subprogram_type
2299 -- in the message, to have a meaningful location. Also
2300 -- indicate if this is an inherited operation, created
2301 -- by a type declaration.
2306 then
2308 Error_Msg_Sloc :=
2310 else
2317 then
2318 -- Special-case the message for universal_fixed
2319 -- operators, which are not declared with the type
2320 -- of the operand, but appear forever in Standard.
2324 then
2325 Error_Msg_N
2328 else
2329 Error_Msg_N
2333 elsif
2335 then
2336 Error_Msg_N
2338 else
2339 Error_Msg_N -- CODEFIX
2346 -- We have a matching interpretation, Expr_Type is the type
2347 -- from this interpretation, and Seen is the entity.
2349 -- For an operator, just set the entity name. The type will be
2350 -- set by the specific operator resolution routine.
2365 -- AI05-0139-2: Expression is overloaded because type has
2366 -- implicit dereference. If type matches context, no implicit
2367 -- dereference is involved.
2378 then
2379 -- If the node is a general indexing, the dereference is
2380 -- is inserted when resolving the rewritten form, else
2381 -- insert it now.
2385 then
2389 -- For an explicit dereference, attribute reference, range,
2390 -- short-circuit form (which is not an operator node), or call
2391 -- with a name that is an explicit dereference, there is
2392 -- nothing to be done at this point.
2395 N_Attribute_Reference,
2396 N_And_Then,
2397 N_Indexed_Component,
2398 N_Or_Else,
2399 N_Range,
2400 N_Selected_Component,
2401 N_Slice)
2403 then
2406 -- For procedure or function calls, set the type of the name,
2407 -- and also the entity pointer for the prefix.
2411 then
2418 then
2423 -- For all other cases, just set the type of the Name
2425 else
2433 -- Move to next interpretation
2441 -- At this stage Found indicates whether or not an acceptable
2442 -- interpretation exists. If not, then we have an error, except that if
2443 -- the context is Any_Type as a result of some other error, then we
2444 -- suppress the error report.
2449 -- If type we are looking for is Void, then this is the procedure
2450 -- call case, and the error is simply that what we gave is not a
2451 -- procedure name (we think of procedure calls as expressions with
2452 -- types internally, but the user doesn't think of them this way).
2456 -- Special case message if function used as a procedure
2461 then
2462 Error_Msg_NE
2466 -- Otherwise give general message (not clear what cases this
2467 -- covers, but no harm in providing for them).
2469 else
2475 -- Otherwise we do have a subexpression with the wrong type
2477 -- Check for the case of an allocator which uses an access type
2478 -- instead of the designated type. This is a common error and we
2479 -- specialize the message, posting an error on the operand of the
2480 -- allocator, complaining that we expected the designated type of
2481 -- the allocator.
2487 then
2491 -- Check for view mismatch on Null in instances, for which the
2492 -- view-swapping mechanism has no identifier.
2498 then
2503 -- Check for an aggregate. Sometimes we can get bogus aggregates
2504 -- from misuse of parentheses, and we are about to complain about
2505 -- the aggregate without even looking inside it.
2507 -- Instead, if we have an aggregate of type Any_Composite, then
2508 -- analyze and resolve the component fields, and then only issue
2509 -- another message if we get no errors doing this (otherwise
2510 -- assume that the errors in the aggregate caused the problem).
2514 then
2515 -- Disable expansion in any case. If there is a type mismatch
2516 -- it may be fatal to try to expand the aggregate. The flag
2517 -- would otherwise be set to false when the error is posted.
2521 declare
2523 -- Check one aggregate, and set Found to True if we have a
2524 -- definite error in any of its elements
2527 -- Check one element of aggregate and set Found to True if
2528 -- we definitely have an error in the element.
2530 ----------------
2531 -- Check_Aggr --
2532 ----------------
2537 begin
2550 -- If this is a default-initialized component, then
2551 -- there is nothing to check. The box will be
2552 -- replaced by the appropriate call during late
2553 -- expansion.
2564 ----------------
2565 -- Check_Elmt --
2566 ----------------
2569 begin
2570 -- If we have a nested aggregate, go inside it (to
2571 -- attempt a naked analyze-resolve of the aggregate can
2572 -- cause undesirable cascaded errors). Do not resolve
2573 -- expression if it needs a type from context, as for
2574 -- integer * fixed expression.
2579 else
2584 then
2594 begin
2599 -- Looks like we have a type error, but check for special case
2600 -- of Address wanted, integer found, with the configuration pragma
2601 -- Allow_Integer_Address active. If we have this case, introduce
2602 -- an unchecked conversion to allow the integer expression to be
2603 -- treated as an Address. The reverse case of integer wanted,
2604 -- Address found, is treated in an analogous manner.
2612 -- That special Allow_Integer_Address check did not appply, so we
2613 -- have a real type error. If an error message was issued already,
2614 -- Found got reset to True, so if it's still False, issue standard
2615 -- Wrong_Type message.
2619 declare
2622 begin
2628 -- Protected operation: retrieve operation name
2632 else
2637 Error_Msg_NE
2643 declare
2647 begin
2654 Error_Msg_NE
2660 else
2664 else
2670 Resolution_Failed;
2673 -- Test if we have more than one interpretation for the context
2676 Resolution_Failed;
2679 -- Only one intepretation
2681 else
2682 -- In Ada 2005, if we have something like "X : T := 2 + 2;", where
2683 -- the "+" on T is abstract, and the operands are of universal type,
2684 -- the above code will have (incorrectly) resolved the "+" to the
2685 -- universal one in Standard. Therefore check for this case and give
2686 -- an error. We can't do this earlier, because it would cause legal
2687 -- cases to get errors (when some other type has an abstract "+").
2693 then
2698 then
2699 Error_Msg_NE
2708 -- Here we have an acceptable interpretation for the context
2710 -- Propagate type information and normalize tree for various
2711 -- predefined operations. If the context only imposes a class of
2712 -- types, rather than a specific type, propagate the actual type
2713 -- downward.
2719 Typ = Any_Discrete
2720 then
2723 -- Any_Fixed is legal in a real context only if a specific fixed-
2724 -- point type is imposed. If Norman Cohen can be confused by this,
2725 -- it deserves a separate message.
2729 then
2736 -- A user-defined operator is transformed into a function call at
2737 -- this point, so that further processing knows that operators are
2738 -- really operators (i.e. are predefined operators). User-defined
2739 -- operators that are intrinsic are just renamings of the predefined
2740 -- ones, and need not be turned into calls either, but if they rename
2741 -- a different operator, we must transform the node accordingly.
2742 -- Instantiations of Unchecked_Conversion are intrinsic but are
2743 -- treated as functions, even if given an operator designator.
2748 then
2754 and then
2756 N_Subprogram_Renaming_Declaration
2757 then
2760 -- If the node is rewritten, it will be fully resolved in
2761 -- Rewrite_Renamed_Operator.
2771 when N_Aggregate => Resolve_Aggregate (N, Ctx_Type);
2773 when N_Allocator => Resolve_Allocator (N, Ctx_Type);
2775 when N_Short_Circuit
2776 => Resolve_Short_Circuit (N, Ctx_Type);
2778 when N_Attribute_Reference
2779 => Resolve_Attribute (N, Ctx_Type);
2781 when N_Case_Expression
2782 => Resolve_Case_Expression (N, Ctx_Type);
2784 when N_Character_Literal
2785 => Resolve_Character_Literal (N, Ctx_Type);
2787 when N_Expanded_Name
2788 => Resolve_Entity_Name (N, Ctx_Type);
2790 when N_Explicit_Dereference
2791 => Resolve_Explicit_Dereference (N, Ctx_Type);
2793 when N_Expression_With_Actions
2794 => Resolve_Expression_With_Actions (N, Ctx_Type);
2796 when N_Extension_Aggregate
2797 => Resolve_Extension_Aggregate (N, Ctx_Type);
2799 when N_Function_Call
2800 => Resolve_Call (N, Ctx_Type);
2802 when N_Identifier
2803 => Resolve_Entity_Name (N, Ctx_Type);
2805 when N_If_Expression
2806 => Resolve_If_Expression (N, Ctx_Type);
2808 when N_Indexed_Component
2809 => Resolve_Indexed_Component (N, Ctx_Type);
2811 when N_Integer_Literal
2812 => Resolve_Integer_Literal (N, Ctx_Type);
2814 when N_Membership_Test
2815 => Resolve_Membership_Op (N, Ctx_Type);
2817 when N_Null => Resolve_Null (N, Ctx_Type);
2819 when N_Op_And | N_Op_Or | N_Op_Xor
2820 => Resolve_Logical_Op (N, Ctx_Type);
2822 when N_Op_Eq | N_Op_Ne
2823 => Resolve_Equality_Op (N, Ctx_Type);
2825 when N_Op_Lt | N_Op_Le | N_Op_Gt | N_Op_Ge
2826 => Resolve_Comparison_Op (N, Ctx_Type);
2828 when N_Op_Not => Resolve_Op_Not (N, Ctx_Type);
2830 when N_Op_Add | N_Op_Subtract | N_Op_Multiply |
2831 N_Op_Divide | N_Op_Mod | N_Op_Rem
2833 => Resolve_Arithmetic_Op (N, Ctx_Type);
2835 when N_Op_Concat => Resolve_Op_Concat (N, Ctx_Type);
2837 when N_Op_Expon => Resolve_Op_Expon (N, Ctx_Type);
2839 when N_Op_Plus | N_Op_Minus | N_Op_Abs
2840 => Resolve_Unary_Op (N, Ctx_Type);
2842 when N_Op_Shift => Resolve_Shift (N, Ctx_Type);
2844 when N_Procedure_Call_Statement
2845 => Resolve_Call (N, Ctx_Type);
2847 when N_Operator_Symbol
2848 => Resolve_Operator_Symbol (N, Ctx_Type);
2850 when N_Qualified_Expression
2851 => Resolve_Qualified_Expression (N, Ctx_Type);
2853 -- Why is the following null, needs a comment ???
2855 when N_Quantified_Expression
2856 => null;
2858 when N_Raise_Expression
2859 => Resolve_Raise_Expression (N, Ctx_Type);
2861 when N_Raise_xxx_Error
2862 => Set_Etype (N, Ctx_Type);
2864 when N_Range => Resolve_Range (N, Ctx_Type);
2866 when N_Real_Literal
2867 => Resolve_Real_Literal (N, Ctx_Type);
2869 when N_Reference => Resolve_Reference (N, Ctx_Type);
2871 when N_Selected_Component
2872 => Resolve_Selected_Component (N, Ctx_Type);
2874 when N_Slice => Resolve_Slice (N, Ctx_Type);
2876 when N_String_Literal
2877 => Resolve_String_Literal (N, Ctx_Type);
2879 when N_Type_Conversion
2880 => Resolve_Type_Conversion (N, Ctx_Type);
2882 when N_Unchecked_Expression =>
2883 Resolve_Unchecked_Expression (N, Ctx_Type);
2885 when N_Unchecked_Type_Conversion =>
2886 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
2887 end case;
2889 -- Ada 2012 (AI05-0149): Apply an (implicit) conversion to an
2890 -- expression of an anonymous access type that occurs in the context
2891 -- of a named general access type, except when the expression is that
2892 -- of a membership test. This ensures proper legality checking in
2893 -- terms of allowed conversions (expressions that would be illegal to
2894 -- convert implicitly are allowed in membership tests).
2896 if Ada_Version >= Ada_2012
2897 and then Ekind (Ctx_Type) = E_General_Access_Type
2898 and then Ekind (Etype (N)) = E_Anonymous_Access_Type
2899 and then Nkind (Parent (N)) not in N_Membership_Test
2900 then
2901 Rewrite (N, Convert_To (Ctx_Type, Relocate_Node (N)));
2902 Analyze_And_Resolve (N, Ctx_Type);
2903 end if;
2905 -- If the subexpression was replaced by a non-subexpression, then
2906 -- all we do is to expand it. The only legitimate case we know of
2907 -- is converting procedure call statement to entry call statements,
2908 -- but there may be others, so we are making this test general.
2910 if Nkind (N) not in N_Subexpr then
2911 Debug_A_Exit ("resolving ", N, " (done)");
2912 Expand (N);
2913 return;
2914 end if;
2916 -- The expression is definitely NOT overloaded at this point, so
2917 -- we reset the Is_Overloaded flag to avoid any confusion when
2918 -- reanalyzing the node.
2920 Set_Is_Overloaded (N, False);
2922 -- Freeze expression type, entity if it is a name, and designated
2923 -- type if it is an allocator (RM 13.14(10,11,13)).
2925 -- Now that the resolution of the type of the node is complete, and
2926 -- we did not detect an error, we can expand this node. We skip the
2927 -- expand call if we are in a default expression, see section
2928 -- "Handling of Default Expressions" in Sem spec.
2930 Debug_A_Exit ("resolving ", N, " (done)");
2932 -- We unconditionally freeze the expression, even if we are in
2933 -- default expression mode (the Freeze_Expression routine tests this
2934 -- flag and only freezes static types if it is set).
2936 -- Ada 2012 (AI05-177): Expression functions do not freeze. Only
2937 -- their use (in an expanded call) freezes.
2939 if Ekind (Proper_Current_Scope) /= E_Function
2940 or else Nkind (Original_Node (Unit_Declaration_Node
2941 (Proper_Current_Scope))) /= N_Expression_Function
2942 then
2943 Freeze_Expression (N);
2944 end if;
2946 -- Now we can do the expansion
2948 Expand (N);
2949 end if;
2950 end Resolve;
2952 -------------
2953 -- Resolve --
2954 -------------
2956 -- Version with check(s) suppressed
2958 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
2959 begin
2960 if Suppress = All_Checks then
2961 declare
2962 Sva : constant Suppress_Array := Scope_Suppress.Suppress;
2963 begin
2964 Scope_Suppress.Suppress := (others => True);
2965 Resolve (N, Typ);
2966 Scope_Suppress.Suppress := Sva;
2967 end;
2969 else
2970 declare
2971 Svg : constant Boolean := Scope_Suppress.Suppress (Suppress);
2972 begin
2973 Scope_Suppress.Suppress (Suppress) := True;
2974 Resolve (N, Typ);
2975 Scope_Suppress.Suppress (Suppress) := Svg;
2976 end;
2977 end if;
2978 end Resolve;
2980 -------------
2981 -- Resolve --
2982 -------------
2984 -- Version with implicit type
2986 procedure Resolve (N : Node_Id) is
2987 begin
2988 Resolve (N, Etype (N));
2989 end Resolve;
2991 ---------------------
2992 -- Resolve_Actuals --
2993 ---------------------
2995 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
2996 Loc : constant Source_Ptr := Sloc (N);
2997 A : Node_Id;
2998 A_Id : Entity_Id;
2999 A_Typ : Entity_Id;
3000 F : Entity_Id;
3001 F_Typ : Entity_Id;
3002 Prev : Node_Id := Empty;
3003 Orig_A : Node_Id;
3005 procedure Check_Argument_Order;
3006 -- Performs a check for the case where the actuals are all simple
3007 -- identifiers that correspond to the formal names, but in the wrong
3008 -- order, which is considered suspicious and cause for a warning.
3010 procedure Check_Prefixed_Call;
3011 -- If the original node is an overloaded call in prefix notation,
3013 -- Try_Object_Operation has already verified that there is a valid
3014 -- interpretation, but the form of the actual can only be determined
3015 -- once the primitive operation is identified.
3018 -- If the actual is missing in a call, insert in the actuals list
3019 -- an instance of the default expression. The insertion is always
3020 -- a named association.
3022 procedure Property_Error
3026 -- Emit an error concerning variable Var with entity Var_Id that has
3027 -- enabled property Prop_Nam when it acts as an actual parameter in a
3028 -- call and the corresponding formal parameter is of mode IN.
3031 -- Check whether T1 and T2, or their full views, are derived from a
3032 -- common type. Used to enforce the restrictions on array conversions
3033 -- of AI95-00246.
3036 -- Predicate to determine whether an actual that is a concatenation
3037 -- will be evaluated statically and does not need a transient scope.
3038 -- This must be determined before the actual is resolved and expanded
3039 -- because if needed the transient scope must be introduced earlier.
3041 --------------------------
3042 -- Check_Argument_Order --
3043 --------------------------
3046 begin
3047 -- Nothing to do if no parameters, or original node is neither a
3048 -- function call nor a procedure call statement (happens in the
3049 -- operator-transformed-to-function call case), or the call does
3050 -- not come from source, or this warning is off.
3052 if not Warn_On_Parameter_Order
3056 then
3060 declare
3063 begin
3064 -- Nothing to do if only one parameter
3070 -- Here if at least two arguments
3072 declare
3078 -- Set True if an out of order case is found
3080 begin
3081 -- Collect identifier names of actuals, fail if any actual is
3082 -- not a simple identifier, and record max length of name.
3088 else
3094 -- If we got this far, all actuals are identifiers and the list
3095 -- of their names is stored in the Actuals array.
3100 -- If we ran out of formals, that's odd, probably an error
3101 -- which will be detected elsewhere, but abandon the search.
3107 -- If name matches and is in order OK
3112 else
3113 -- If no match, see if it is elsewhere in list and if so
3114 -- flag potential wrong order if type is compatible.
3118 and then
3120 then
3126 -- No match
3134 -- If Formals left over, also probably an error, skip warning
3140 -- Here we give the warning if something was out of order
3143 Error_Msg_N
3150 -------------------------
3151 -- Check_Prefixed_Call --
3152 -------------------------
3161 begin
3162 -- Check whether the call is a prefixed call, with or without
3163 -- additional actuals.
3166 or else
3172 then
3175 then
3176 -- Introduce dereference on object in prefix
3178 New_A :=
3186 then
3187 -- Introduce an implicit 'Access in prefix
3190 Error_Msg_NE
3206 --------------------
3207 -- Insert_Default --
3208 --------------------
3214 begin
3215 -- Missing argument in call, nothing to insert
3220 else
3221 -- Note that we do a full New_Copy_Tree, so that any associated
3222 -- Itypes are properly copied. This may not be needed any more,
3223 -- but it does no harm as a safety measure. Defaults of a generic
3224 -- formal may be out of bounds of the corresponding actual (see
3225 -- cc1311b) and an additional check may be required.
3227 Actval :=
3228 New_Copy_Tree
3235 then
3241 then
3244 then
3245 -- If default is a real literal, do not introduce a
3246 -- conversion whose effect may depend on the run-time
3247 -- size of universal real.
3251 else
3262 -- Resolve aggregates with their base type, to avoid scope
3263 -- anomalies: the subtype was first built in the subprogram
3264 -- declaration, and the current call may be nested.
3268 else
3272 else
3275 -- See note above concerning aggregates
3279 then
3282 -- Resolve entities with their own type, which may differ from
3283 -- the type of a reference in a generic context (the view
3284 -- swapping mechanism did not anticipate the re-analysis of
3285 -- default values in calls).
3290 else
3295 -- If default is a tag indeterminate function call, propagate tag
3296 -- to obtain proper dispatching.
3300 then
3306 -- If the default expression raises constraint error, then just
3307 -- silently replace it with an N_Raise_Constraint_Error node, since
3308 -- we already gave the warning on the subprogram spec. If node is
3309 -- already a Raise_Constraint_Error leave as is, to prevent loops in
3310 -- the warnings removal machinery.
3314 then
3322 Assoc :=
3327 -- Case of insertion is first named actual
3331 then
3338 else
3342 else
3346 -- Case of insertion is not first named actual
3348 else
3349 Set_Next_Named_Actual
3361 --------------------
3362 -- Property_Error --
3363 --------------------
3365 procedure Property_Error
3369 is
3370 begin
3372 Error_Msg_NE
3378 -------------------
3379 -- Same_Ancestor --
3380 -------------------
3386 begin
3389 then
3395 then
3402 --------------------------
3403 -- Static_Concatenation --
3404 --------------------------
3407 begin
3414 -- Concatenation is static when both operands are static and
3415 -- the concatenation operator is a predefined one.
3418 and then
3420 and then
3425 declare
3427 begin
3430 and then
3434 else
3440 -- Start of processing for Resolve_Actuals
3442 begin
3443 Check_Argument_Order;
3447 Check_Prefixed_Call;
3456 -- If we have an error in any actual or formal, indicated by a type
3457 -- of Any_Type, then abandon resolution attempt, and set result type
3458 -- to Any_Type. Skip this if the actual is a Raise_Expression, whose
3459 -- type is imposed from context.
3463 then
3470 -- Case where actual is present
3472 -- If the actual is an entity, generate a reference to it now. We
3473 -- do this before the actual is resolved, because a formal of some
3474 -- protected subprogram, or a task discriminant, will be rewritten
3475 -- during expansion, and the source entity reference may be lost.
3480 then
3486 then
3493 -- RM 6.4.1(12): For an out parameter that is passed by
3494 -- copy, the formal parameter object is created, and:
3496 -- * For an access type, the formal parameter is initialized
3497 -- from the value of the actual, without checking that the
3498 -- value satisfies any constraint, any predicate, or any
3499 -- exclusion of the null value.
3501 -- * For a scalar type that has the Default_Value aspect
3502 -- specified, the formal parameter is initialized from the
3503 -- value of the actual, without checking that the value
3504 -- satisfies any constraint or any predicate.
3505 -- I do not understand why this case is included??? this is
3506 -- not a case where an OUT parameter is treated as IN OUT.
3508 -- * For a composite type with discriminants or that has
3509 -- implicit initial values for any subcomponents, the
3510 -- behavior is as for an in out parameter passed by copy.
3512 -- Hence for these cases we generate the read reference now
3513 -- (the write reference will be generated later by
3514 -- Note_Possible_Modification).
3517 and then
3519 or else
3521 and then
3523 or else
3526 or else Is_Partially_Initialized_Type
3528 then
3538 then
3539 -- If style checking mode on, check match of formal name
3547 -- If the formal is Out or In_Out, do not resolve and expand the
3548 -- conversion, because it is subsequently expanded into explicit
3549 -- temporaries and assignments. However, the object of the
3550 -- conversion can be resolved. An exception is the case of tagged
3551 -- type conversion with a class-wide actual. In that case we want
3552 -- the tag check to occur and no temporary will be needed (no
3553 -- representation change can occur) and the parameter is passed by
3554 -- reference, so we go ahead and resolve the type conversion.
3555 -- Another exception is the case of reference to component or
3556 -- subcomponent of a bit-packed array, in which case we want to
3557 -- defer expansion to the point the in and out assignments are
3558 -- performed.
3563 then
3566 then
3567 -- In a view conversion, the conversion must be legal in
3568 -- both directions, and thus both component types must be
3569 -- aliased, or neither (4.6 (8)).
3571 -- The extra rule in 4.6 (24.9.2) seems unduly restrictive:
3572 -- the privacy requirement should not apply to generic
3573 -- types, and should be checked in an instance. ARG query
3574 -- is in order ???
3578 then
3579 Error_Msg_N
3583 -- Comment here??? what set of cases???
3585 elsif
3587 then
3588 -- Check view conv between unrelated by ref array types
3592 then
3593 Error_Msg_N
3597 -- In Ada 2005 mode, check view conversion component
3598 -- type cannot be private, tagged, or volatile. Note
3599 -- that we only apply this to source conversions. The
3600 -- generated code can contain conversions which are
3601 -- not subject to this test, and we cannot extract the
3602 -- component type in such cases since it is not present.
3606 then
3607 declare
3609 Component_Type
3611 begin
3616 then
3617 Error_Msg_N
3628 -- Resolve expression if conversion is all OK
3633 then
3637 -- If the actual is a function call that returns a limited
3638 -- unconstrained object that needs finalization, create a
3639 -- transient scope for it, so that it can receive the proper
3640 -- finalization list.
3645 and then Expander_Active
3647 then
3651 -- A small optimization: if one of the actuals is a concatenation
3652 -- create a block around a procedure call to recover stack space.
3653 -- This alleviates stack usage when several procedure calls in
3654 -- the same statement list use concatenation. We do not perform
3655 -- this wrapping for code statements, where the argument is a
3656 -- static string, and we want to preserve warnings involving
3657 -- sequences of such statements.
3661 and then Expander_Active
3662 and then
3666 then
3670 else
3674 and then
3677 then
3678 Error_Msg_N
3691 -- (Ada 2005: AI-251): If the actual is an allocator whose
3692 -- directly designated type is a class-wide interface, we build
3693 -- an anonymous access type to use it as the type of the
3694 -- allocator. Later, when the subprogram call is expanded, if
3695 -- the interface has a secondary dispatch table the expander
3696 -- will add a type conversion to force the correct displacement
3697 -- of the pointer.
3700 declare
3706 begin
3709 then
3712 Set_Directly_Designated_Type
3717 -- Ada 2005, AI-162:If the actual is an allocator, the
3718 -- innermost enclosing statement is the master of the
3719 -- created object. This needs to be done with expansion
3720 -- enabled only, otherwise the transient scope will not
3721 -- be removed in the expansion of the wrapped construct.
3724 and then Expander_Active
3725 then
3735 -- (Ada 2005): The call may be to a primitive operation of a
3736 -- tagged synchronized type, declared outside of the type. In
3737 -- this case the controlling actual must be converted to its
3738 -- corresponding record type, which is the formal type. The
3739 -- actual may be a subtype, either because of a constraint or
3740 -- because it is a generic actual, so use base type to locate
3741 -- concurrent type.
3748 then
3749 -- If the actual is overloaded, look for an interpretation
3750 -- that has a synchronized type.
3755 else
3756 declare
3760 begin
3765 then
3775 declare
3778 begin
3781 else
3785 -- Tagged synchronized type (case 1): the actual is a
3786 -- concurrent type.
3790 then
3792 Unchecked_Convert_To
3796 -- Tagged synchronized type (case 2): the formal is a
3797 -- concurrent type.
3800 and then Present
3805 then
3808 -- Common case
3810 else
3815 -- Not a synchronized operation
3817 else
3827 N_Procedure_Call_Statement)
3828 then
3829 -- In formal mode, check that actual parameters matching
3830 -- formals of tagged types are objects (or ancestor type
3831 -- conversions of objects), not general expressions.
3838 declare
3843 begin
3845 Check_SPARK_Restriction
3848 -- In formal mode, the only view conversions are those
3849 -- involving ancestor conversion of an extended type.
3851 elsif not
3857 then
3858 if Ekind_In
3860 then
3861 Check_SPARK_Restriction
3864 else
3865 Check_SPARK_Restriction
3869 else
3874 else
3878 -- In formal mode, the only view conversions are those
3879 -- involving ancestor conversion of an extended type.
3883 then
3884 Check_SPARK_Restriction
3890 -- has warnings suppressed, then we reset Never_Set_In_Source for
3891 -- the calling entity. The reason for this is to catch cases like
3892 -- GNAT.Spitbol.Patterns.Vstring_Var where the called subprogram
3893 -- uses trickery to modify an IN parameter.
3900 then
3904 -- Perform error checks for IN and IN OUT parameters
3908 -- Check unset reference. For scalar parameters, it is clearly
3909 -- wrong to pass an uninitialized value as either an IN or
3910 -- IN-OUT parameter. For composites, it is also clearly an
3911 -- error to pass a completely uninitialized value as an IN
3912 -- parameter, but the case of IN OUT is trickier. We prefer
3913 -- not to give a warning here. For example, suppose there is
3914 -- a routine that sets some component of a record to False.
3915 -- It is perfectly reasonable to make this IN-OUT and allow
3916 -- either initialized or uninitialized records to be passed
3917 -- in this case.
3919 -- For partially initialized composite values, we also avoid
3920 -- warnings, since it is quite likely that we are passing a
3921 -- partially initialized value and only the initialized fields
3922 -- will in fact be read in the subprogram.
3927 then
3931 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
3932 -- actual to a nested call, since this is case of reading an
3933 -- out parameter, which is not allowed.
3938 then
3943 -- Case of OUT or IN OUT parameter
3947 -- For an Out parameter, check for useless assignment. Note
3948 -- that we can't set Last_Assignment this early, because we may
3949 -- kill current values in Resolve_Call, and that call would
3950 -- clobber the Last_Assignment field.
3952 -- Note: call Warn_On_Useless_Assignment before doing the check
3953 -- below for Is_OK_Variable_For_Out_Formal so that the setting
3954 -- of Referenced_As_LHS/Referenced_As_Out_Formal properly
3955 -- reflects the last assignment, not this one.
3962 then
3967 -- Validate the form of the actual. Note that the call to
3968 -- Is_OK_Variable_For_Out_Formal generates the required
3969 -- reference in this case.
3971 -- A call to an initialization procedure for an aggregate
3972 -- component may initialize a nested component of a constant
3973 -- designated object. In this context the object is variable.
3977 then
3981 and then
3984 then
3985 Error_Msg_N
3991 -- What's the following about???
3995 else
3996 Kill_All_Checks;
4005 -- Apply appropriate range checks for in, out, and in-out
4006 -- parameters. Out and in-out parameters also need a separate
4007 -- check, if there is a type conversion, to make sure the return
4008 -- value meets the constraints of the variable before the
4009 -- conversion.
4011 -- Gigi looks at the check flag and uses the appropriate types.
4012 -- For now since one flag is used there is an optimization which
4013 -- might not be done in the In Out case since Gigi does not do
4014 -- any analysis. More thought required about this ???
4018 -- Apply predicate checks, unless this is a call to the
4019 -- predicate check function itself, which would cause an
4020 -- infinite recursion, or it is a call to an initialization
4021 -- procedure whose operand is of course an unfinished object.
4025 or else
4028 then
4032 -- Apply required constraint checks
4045 then
4048 -- For view conversions of a discriminated object, apply
4049 -- check to object itself, the conversion alreay has the
4050 -- proper type.
4054 then
4061 then
4067 then
4070 else
4074 -- Ada 2005 (AI-231): Note that the controlling parameter case
4075 -- already existed in Ada 95, which is partially checked
4076 -- elsewhere (see Checks), and we don't want the warning
4077 -- message to differ.
4082 then
4084 Apply_Compile_Time_Constraint_Error
4090 Apply_Compile_Time_Constraint_Error
4102 Apply_Scalar_Range_Check
4104 else
4105 Apply_Range_Check
4109 else
4114 then
4116 else
4122 -- An actual associated with an access parameter is implicitly
4123 -- converted to the anonymous access type of the formal and must
4124 -- satisfy the legality checks for access conversions.
4128 Error_Msg_N
4132 -- If the actual is an access selected component of a variable,
4133 -- the call may modify its designated object. It is reasonable
4134 -- to treat this as a potential modification of the enclosing
4135 -- record, to prevent spurious warnings that it should be
4136 -- declared as a constant, because intuitively programmers
4137 -- regard the designated subcomponent as part of the record.
4142 then
4147 -- Check bad case of atomic/volatile argument (RM C.6(12))
4151 then
4154 then
4155 Error_Msg_NE
4161 then
4162 Error_Msg_NE
4168 -- Check that subprograms don't have improper controlling
4169 -- arguments (RM 3.9.2 (9)).
4171 -- A primitive operation may have an access parameter of an
4172 -- incomplete tagged type, but a dispatching call is illegal
4173 -- if the type is still incomplete.
4179 declare
4181 begin
4185 then
4186 Error_Msg_NE
4200 then
4205 then
4207 Error_Msg_NE
4211 -- Apply the checks described in 3.10.2(27): if the context is a
4212 -- specific access-to-object, the actual cannot be class-wide.
4213 -- Use base type to exclude access_to_subprogram cases.
4220 and then
4225 -- Disable these checks for call to imported C++ subprograms
4227 and then not
4231 then
4232 Error_Msg_N
4237 Error_Msg_NE
4244 -- If it is a named association, treat the selector_name as a
4245 -- proper identifier, and mark the corresponding entity.
4249 -- Ignore reference in SPARK mode, as it refers to an entity not
4250 -- in scope at the point of reference, so the reference should
4251 -- be ignored for computing effects of subprograms.
4253 and then not GNATprove_Mode
4254 then
4267 -- The following checks are only relevant when SPARK_Mode is on as
4268 -- they are not standard Ada legality rule.
4272 then
4273 -- A volatile object may act as an actual parameter when the
4274 -- corresponding formal is of a non-scalar volatile type.
4278 then
4281 -- A volatile object may act as an actual parameter in a call
4282 -- to an instance of Unchecked_Conversion.
4287 else
4288 Error_Msg_N
4293 -- Detect an external variable with an enabled property that
4294 -- does not match the mode of the corresponding formal in a
4295 -- procedure call.
4297 -- why only procedure calls ???
4303 then
4317 then
4319 Error_Msg_NE
4323 Error_Msg_N
4331 -- Case where actual is not present
4333 else
4334 Insert_Default;
4341 -----------------------
4342 -- Resolve_Allocator --
4343 -----------------------
4355 procedure Check_Allocator_Discrim_Accessibility
4358 -- Check that accessibility level associated with an access discriminant
4359 -- initialized in an allocator by the expression Disc_Exp is not deeper
4360 -- than the level of the allocator type Alloc_Typ. An error message is
4361 -- issued if this condition is violated. Specialized checks are done for
4362 -- the cases of a constraint expression which is an access attribute or
4363 -- an access discriminant.
4366 -- If the allocator is an actual in a call, it is allowed to be class-
4367 -- wide when the context is not because it is a controlling actual.
4369 -------------------------------------------
4370 -- Check_Allocator_Discrim_Accessibility --
4371 -------------------------------------------
4373 procedure Check_Allocator_Discrim_Accessibility
4376 is
4377 begin
4380 then
4381 Error_Msg_N
4384 -- When the expression is an Access attribute the level of the prefix
4385 -- object must not be deeper than that of the allocator's type.
4389 Attribute_Access
4392 then
4393 Error_Msg_N
4395 Disc_Exp);
4397 -- When the expression is an access discriminant the check is against
4398 -- the level of the prefix object.
4404 then
4405 Error_Msg_N
4407 Disc_Exp);
4409 -- All other cases are legal
4411 else
4416 ----------------------------
4417 -- In_Dispatching_Context --
4418 ----------------------------
4423 begin
4429 -- Start of processing for Resolve_Allocator
4431 begin
4432 -- Replace general access with specific type
4442 -- For qualified expression, resolve the expression using the given
4443 -- subtype (nothing to do for type mark, subtype indication)
4448 and then not In_Dispatching_Context
4449 then
4450 Error_Msg_N
4457 -- A qualified expression requires an exact match of the type.
4458 -- Class-wide matching is not allowed.
4463 then
4467 -- Calls to build-in-place functions are not currently supported in
4468 -- allocators for access types associated with a simple storage pool.
4469 -- Supporting such allocators may require passing additional implicit
4470 -- parameters to build-in-place functions (or a significant revision
4471 -- of the current b-i-p implementation to unify the handling for
4472 -- multiple kinds of storage pools). ???
4476 then
4477 declare
4480 begin
4482 and then
4483 Present (Get_Rep_Pragma
4485 then
4486 Error_Msg_N
4493 -- A special accessibility check is needed for allocators that
4494 -- constrain access discriminants. The level of the type of the
4495 -- expression used to constrain an access discriminant cannot be
4496 -- deeper than the type of the allocator (in contrast to access
4497 -- parameters, where the level of the actual can be arbitrary).
4499 -- We can't use Valid_Conversion to perform this check because in
4500 -- general the type of the allocator is unrelated to the type of
4501 -- the access discriminant.
4505 then
4512 then
4515 -- Get the first component expression of the aggregate
4525 else
4529 else
4548 else
4553 else
4562 -- For a subtype mark or subtype indication, freeze the subtype
4564 else
4568 Error_Msg_N
4572 -- A special accessibility check is needed for allocators that
4573 -- constrain access discriminants. The level of the type of the
4574 -- expression used to constrain an access discriminant cannot be
4575 -- deeper than the type of the allocator (in contrast to access
4576 -- parameters, where the level of the actual can be arbitrary).
4577 -- We can't use Valid_Conversion to perform this check because
4578 -- in general the type of the allocator is unrelated to the type
4579 -- of the access discriminant.
4584 then
4594 else
4608 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
4609 -- check that the level of the type of the created object is not deeper
4610 -- than the level of the allocator's access type, since extensions can
4611 -- now occur at deeper levels than their ancestor types. This is a
4612 -- static accessibility level check; a run-time check is also needed in
4613 -- the case of an initialized allocator with a class-wide argument (see
4614 -- Expand_Allocator_Expression).
4618 then
4619 declare
4622 begin
4627 else
4633 then
4636 Error_Msg_N
4645 -- Do not apply Ada 2005 accessibility checks on a class-wide
4646 -- allocator if the type given in the allocator is a formal
4647 -- type. A run-time check will be performed in the instance.
4657 -- Check for allocation from an empty storage pool
4662 -- If the context is an unchecked conversion, as may happen within an
4663 -- inlined subprogram, the allocator is being resolved with its own
4664 -- anonymous type. In that case, if the target type has a specific
4665 -- storage pool, it must be inherited explicitly by the allocator type.
4669 then
4670 Set_Associated_Storage_Pool
4678 -- Check that an allocator with task parts isn't for a nested access
4679 -- type when restriction No_Task_Hierarchy applies.
4683 then
4687 -- An erroneous allocator may be rewritten as a raise Program_Error
4688 -- statement.
4692 -- An anonymous access discriminant is the definition of a
4693 -- coextension.
4697 N_Discriminant_Specification
4698 then
4699 declare
4703 begin
4706 -- Ada 2012 AI05-0052: If the designated type of the allocator
4707 -- is limited, then the allocator shall not be used to define
4708 -- the value of an access discriminant unless the discriminated
4709 -- type is immutably limited.
4714 then
4715 Error_Msg_N
4721 -- Avoid marking an allocator as a dynamic coextension if it is
4722 -- within a static construct.
4728 -- Cleanup for potential static coextensions
4730 else
4736 -- Report a simple error: if the designated object is a local task,
4737 -- its body has not been seen yet, and its activation will fail an
4738 -- elaboration check.
4745 then
4751 -- Ada 2012 (AI05-0111-3): Detect an attempt to allocate a task or a
4752 -- type with a task component on a subpool. This action must raise
4753 -- Program_Error at runtime.
4759 then
4771 ---------------------------
4772 -- Resolve_Arithmetic_Op --
4773 ---------------------------
4775 -- Used for resolving all arithmetic operators except exponentiation
4786 -- We do the resolution using the base type, because intermediate values
4787 -- in expressions always are of the base type, not a subtype of it.
4790 -- Returns True if N is in a context that expects "any real type"
4793 -- Return True iff given type is Integer or universal real/integer
4796 -- Choose type of integer literal in fixed-point operation to conform
4797 -- to available fixed-point type. T is the type of the other operand,
4798 -- which is needed to determine the expected type of N.
4801 -- Set operand type to T if universal
4803 -------------------------------
4804 -- Expected_Type_Is_Any_Real --
4805 -------------------------------
4808 begin
4809 -- N is the expression after "delta" in a fixed_point_definition;
4810 -- see RM-3.5.9(6):
4813 N_Decimal_Fixed_Point_Definition,
4815 -- N is one of the bounds in a real_range_specification;
4816 -- see RM-3.5.7(5):
4818 N_Real_Range_Specification,
4820 -- N is the expression of a delta_constraint;
4821 -- see RM-J.3(3):
4823 N_Delta_Constraint);
4826 -----------------------------
4827 -- Is_Integer_Or_Universal --
4828 -----------------------------
4835 begin
4841 else
4847 then
4858 ----------------------------
4859 -- Set_Mixed_Mode_Operand --
4860 ----------------------------
4866 begin
4869 -- A universal integer literal is resolved as standard integer
4870 -- except in the case of a fixed-point result, where we leave it
4871 -- as universal (to be handled by Exp_Fixd later on)
4875 else
4883 then
4884 -- A universal real can appear in a fixed-type context. We resolve
4885 -- the literal with that context, even though this might raise an
4886 -- exception prematurely (the other operand may be zero).
4893 then
4894 -- Integer arg in mixed-mode operation. Resolve with universal
4895 -- type, in case preference rule must be applied.
4901 then
4902 -- Not a mixed-mode operation, resolve with context
4908 -- N may itself be a mixed-mode operation, so use context type
4915 then
4916 -- Must be (fixed * fixed) operation, operand must have one
4917 -- compatible interpretation.
4924 then
4925 -- C * F(X) in a fixed context, where C is a real literal or a
4926 -- fixed-point expression. F must have either a fixed type
4927 -- interpretation or an integer interpretation, but not both.
4934 else
4941 else
4949 -- Reanalyze the literal with the fixed type of the context. If
4950 -- context is Universal_Fixed, we are within a conversion, leave
4951 -- the literal as a universal real because there is no usable
4952 -- fixed type, and the target of the conversion plays no role in
4953 -- the resolution.
4955 declare
4959 begin
4962 else
4968 then
4970 else
4978 else
4983 ----------------------
4984 -- Set_Operand_Type --
4985 ----------------------
4988 begin
4991 then
4996 -- Start of processing for Resolve_Arithmetic_Op
4998 begin
5003 then
5007 -- Special-case for mixed-mode universal expressions or fixed point type
5008 -- operation: each argument is resolved separately. The same treatment
5009 -- is required if one of the operands of a fixed point operation is
5010 -- universal real, since in this case we don't do a conversion to a
5011 -- specific fixed-point type (instead the expander handles the case).
5013 -- Set the type of the node to its universal interpretation because
5014 -- legality checks on an exponentiation operand need the context.
5019 then
5030 or else
5033 then
5038 -- If context is a fixed type and one operand is integer, the other
5039 -- is resolved with the type of the context.
5044 then
5051 then
5055 else
5060 -- Check the rule in RM05-4.5.5(19.1/2) disallowing universal_fixed
5061 -- multiplying operators from being used when the expected type is
5062 -- also universal_fixed. Note that B_Typ will be Universal_Fixed in
5063 -- some cases where the expected type is actually Any_Real;
5064 -- Expected_Type_Is_Any_Real takes care of that case.
5068 then
5072 N_Unchecked_Type_Conversion)
5073 then
5080 else
5083 and then not
5085 N_Unchecked_Type_Conversion)
5086 then
5087 Error_Msg_N
5092 -- The expected type is "any real type" in contexts like
5094 -- type T is delta <universal_fixed-expression> ...
5096 -- in which case we need to set the type to Universal_Real
5097 -- so that static expression evaluation will work properly.
5101 else
5111 then
5116 -- If no previous errors, this is only possible if one operand is
5117 -- overloaded and the context is universal. Resolve as such.
5122 else
5124 and then
5126 then
5130 -- If the context is Universal_Fixed and the operands are also
5131 -- universal fixed, this is an error, unless there is only one
5132 -- applicable fixed_point type (usually Duration).
5140 else
5145 else
5150 -- If one of the arguments was resolved to a non-universal type.
5151 -- label the result of the operation itself with the same type.
5152 -- Do the same for the universal argument, if any.
5164 -- In SPARK, a multiplication or division with operands of fixed point
5165 -- types shall be qualified or explicitly converted to identify the
5166 -- result type.
5171 and then
5173 then
5174 Check_SPARK_Restriction
5178 -- Set overflow and division checking bit
5185 -- Give warning if explicit division by zero
5189 then
5195 or else
5198 then
5199 -- Specialize the warning message according to the operation.
5200 -- The following warnings are for the case
5205 -- For division, we have two cases, for float division
5206 -- of an unconstrained float type, on a machine where
5207 -- Machine_Overflows is false, we don't get an exception
5208 -- at run-time, but rather an infinity or Nan. The Nan
5209 -- case is pretty obscure, so just warn about infinities.
5213 and then not Machine_Overflows_On_Target
5214 then
5215 Error_Msg_N
5219 -- For all other cases, we get a Constraint_Error
5221 else
5222 Apply_Compile_Time_Constraint_Error
5228 Apply_Compile_Time_Constraint_Error
5233 Apply_Compile_Time_Constraint_Error
5237 -- Division by zero can only happen with division, rem,
5238 -- and mod operations.
5244 -- Otherwise just set the flag to check at run time
5246 else
5251 -- If Restriction No_Implicit_Conditionals is active, then it is
5252 -- violated if either operand can be negative for mod, or for rem
5253 -- if both operands can be negative.
5257 then
5258 declare
5265 -- Set if corresponding operand might be negative
5267 begin
5268 Determine_Range
5272 Determine_Range
5276 -- Check if we will be generating conditionals. There are two
5277 -- cases where that can happen, first for REM, the only case
5278 -- is largest negative integer mod -1, where the division can
5279 -- overflow, but we still have to give the right result. The
5280 -- front end generates a test for this annoying case. Here we
5281 -- just test if both operands can be negative (that's what the
5282 -- expander does, so we match its logic here).
5284 -- The second case is mod where either operand can be negative.
5285 -- In this case, the back end has to generate additional tests.
5288 or else
5290 then
5302 ------------------
5303 -- Resolve_Call --
5304 ------------------
5316 function Same_Or_Aliased_Subprograms
5319 -- Returns True if the subprogram entity S is the same as E or else
5320 -- S is an alias of E.
5322 ---------------------------------
5323 -- Same_Or_Aliased_Subprograms --
5324 ---------------------------------
5326 function Same_Or_Aliased_Subprograms
5329 is
5331 begin
5335 -- Start of processing for Resolve_Call
5337 begin
5338 -- The context imposes a unique interpretation with type Typ on a
5339 -- procedure or function call. Find the entity of the subprogram that
5340 -- yields the expected type, and propagate the corresponding formal
5341 -- constraints on the actuals. The caller has established that an
5342 -- interpretation exists, and emitted an error if not unique.
5344 -- First deal with the case of a call to an access-to-subprogram,
5345 -- dereference made explicit in Analyze_Call.
5351 else
5352 -- Find the interpretation whose type (a subprogram type) has a
5353 -- return type that is compatible with the context. Analysis of
5354 -- the node has established that one exists.
5373 -- If the prefix is not an entity, then resolve it
5379 -- For an indirect call, we always invalidate checks, since we do not
5380 -- know whether the subprogram is local or global. Yes we could do
5381 -- better here, e.g. by knowing that there are no local subprograms,
5382 -- but it does not seem worth the effort. Similarly, we kill all
5383 -- knowledge of current constant values.
5385 Kill_Current_Values;
5387 -- If this is a procedure call which is really an entry call, do
5388 -- the conversion of the procedure call to an entry call. Protected
5389 -- operations use the same circuitry because the name in the call
5390 -- can be an arbitrary expression with special resolution rules.
5395 then
5399 -- Kill checks and constant values, as above for indirect case
5400 -- Who knows what happens when another task is activated?
5402 Kill_Current_Values;
5405 -- Normal subprogram call with name established in Resolve
5411 -- Otherwise we must have the case of an overloaded call
5413 else
5416 -- Initialize Nam to prevent warning (we know it will be assigned
5417 -- in the loop below, but the compiler does not know that).
5437 then
5438 -- The prefix is a parameterless function call that returns an access
5439 -- to subprogram. If parameters are present in the current call, add
5440 -- add an explicit dereference. We use the base type here because
5441 -- within an instance these may be subtypes.
5443 -- The dereference is added either in Analyze_Call or here. Should
5444 -- be consolidated ???
5453 -- Check that a call to Current_Task does not occur in an entry body
5456 declare
5459 begin
5461 loop
5464 -- Exclude calls that occur within the default of a formal
5465 -- parameter of the entry, since those are evaluated outside
5466 -- of the body.
5473 then
5476 Error_Msg_NE
5490 -- Check that a procedure call does not occur in the context of the
5491 -- entry call statement of a conditional or timed entry call. Note that
5492 -- the case of a call to a subprogram renaming of an entry will also be
5493 -- rejected. The test for N not being an N_Entry_Call_Statement is
5494 -- defensive, covering the possibility that the processing of entry
5495 -- calls might reach this point due to later modifications of the code
5496 -- above.
5501 then
5505 -- Ada 2005 (AI-345): If a procedure_call_statement is used
5506 -- for a procedure_or_entry_call, the procedure_name or
5507 -- procedure_prefix of the procedure_call_statement shall denote
5508 -- an entry renamed by a procedure, or (a view of) a primitive
5509 -- subprogram of a limited interface whose first parameter is
5510 -- a controlling parameter.
5515 then
5516 Error_Msg_N
5521 -- If the SPARK_05 restriction is active, we are not allowed
5522 -- to have a call to a subprogram before we see its completion.
5527 -- Don't flag strange internal calls
5532 -- Only flag calls in extended main source
5537 -- Exclude enumeration literals from this processing
5540 then
5541 Check_SPARK_Restriction
5545 -- Check that this is not a call to a protected procedure or entry from
5546 -- within a protected function.
5550 -- Freeze the subprogram name if not in a spec-expression. Note that
5551 -- we freeze procedure calls as well as function calls. Procedure calls
5552 -- are not frozen according to the rules (RM 13.14(14)) because it is
5553 -- impossible to have a procedure call to a non-frozen procedure in
5554 -- pure Ada, but in the code that we generate in the expander, this
5555 -- rule needs extending because we can generate procedure calls that
5556 -- need freezing.
5558 -- In Ada 2012, expression functions may be called within pre/post
5559 -- conditions of subsequent functions or expression functions. Such
5560 -- calls do not freeze when they appear within generated bodies,
5561 -- (including the body of another expression function) which would
5562 -- place the freeze node in the wrong scope. An expression function
5563 -- is frozen in the usual fashion, by the appearance of a real body,
5564 -- or at the end of a declarative part.
5568 and then
5571 then
5575 -- For a predefined operator, the type of the result is the type imposed
5576 -- by context, except for a predefined operation on universal fixed.
5577 -- Otherwise The type of the call is the type returned by the subprogram
5578 -- being called.
5585 -- If the subprogram returns an array type, and the context requires the
5586 -- component type of that array type, the node is really an indexing of
5587 -- the parameterless call. Resolve as such. A pathological case occurs
5588 -- when the type of the component is an access to the array type. In
5589 -- this case the call is truly ambiguous.
5592 and then
5595 or else
5598 and then
5600 then
5601 declare
5606 begin
5609 then
5610 Error_Msg_N
5612 else
5615 -- The called entity may be an explicit dereference, in which
5616 -- case there is no entity to set.
5624 or else
5626 and then
5628 then
5631 -- Indexed call to a parameterless function
5633 Index_Node :=
5635 Prefix =>
5639 else
5640 -- An Ada 2005 prefixed call to a primitive operation
5641 -- whose first parameter is the prefix. This prefix was
5642 -- prepended to the parameter list, which is actually a
5643 -- list of indexes. Remove the prefix in order to build
5644 -- the proper indexed component.
5646 Index_Node :=
5648 Prefix =>
5651 Parameter_Associations =>
5652 New_List
5657 -- Preserve the parenthesis count of the node
5661 -- Since we are correcting a node classification error made
5662 -- by the parser, we call Replace rather than Rewrite.
5676 else
5680 -- In the case where the call is to an overloaded subprogram, Analyze
5681 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
5682 -- such a case Normalize_Actuals needs to be called once more to order
5683 -- the actuals correctly. Otherwise the call will have the ordering
5684 -- given by the last overloaded subprogram whether this is the correct
5685 -- one being called or not.
5692 -- In any case, call is fully resolved now. Reset Overload flag, to
5693 -- prevent subsequent overload resolution if node is analyzed again
5698 -- If we are calling the current subprogram from immediately within its
5699 -- body, then that is the case where we can sometimes detect cases of
5700 -- infinite recursion statically. Do not try this in case restriction
5701 -- No_Recursion is in effect anyway, and do it only for source calls.
5706 -- Check violation of SPARK_05 restriction which does not permit
5707 -- a subprogram body to contain a call to the subprogram directly.
5711 then
5712 Check_SPARK_Restriction
5716 -- Issue warning for possible infinite recursion in the absence
5717 -- of the No_Recursion restriction.
5722 then
5723 -- Here we detected and flagged an infinite recursion, so we do
5724 -- not need to test the case below for further warnings. Also we
5725 -- are all done if we now have a raise SE node.
5731 -- If call is to immediately containing subprogram, then check for
5732 -- the case of a possible run-time detectable infinite recursion.
5734 else
5738 -- Although in general case, recursion is not statically
5739 -- checkable, the case of calling an immediately containing
5740 -- subprogram is easy to catch.
5744 -- If the recursive call is to a parameterless subprogram,
5745 -- then even if we can't statically detect infinite
5746 -- recursion, this is pretty suspicious, and we output a
5747 -- warning. Furthermore, we will try later to detect some
5748 -- cases here at run time by expanding checking code (see
5749 -- Detect_Infinite_Recursion in package Exp_Ch6).
5751 -- If the recursive call is within a handler, do not emit a
5752 -- warning, because this is a common idiom: loop until input
5753 -- is correct, catch illegal input in handler and restart.
5759 then
5760 -- For the case of a procedure call. We give the message
5761 -- only if the call is the first statement in a sequence
5762 -- of statements, or if all previous statements are
5763 -- simple assignments. This is simply a heuristic to
5764 -- decrease false positives, without losing too many good
5765 -- warnings. The idea is that these previous statements
5766 -- may affect global variables the procedure depends on.
5767 -- We also exclude raise statements, that may arise from
5768 -- constraint checks and are probably unrelated to the
5769 -- intended control flow.
5773 then
5774 declare
5776 begin
5780 N_Assignment_Statement,
5781 N_Raise_Constraint_Error)
5782 then
5791 -- Do not give warning if we are in a conditional context
5793 declare
5795 begin
5801 then
5806 -- Here warning is to be issued
5822 -- Check obsolescent reference to Ada.Characters.Handling subprogram
5826 -- If subprogram name is a predefined operator, it was given in
5827 -- functional notation. Replace call node with operator node, so
5828 -- that actuals can be resolved appropriately.
5836 then
5842 -- Create a transient scope if the resulting type requires it
5844 -- There are several notable exceptions:
5846 -- a) In init procs, the transient scope overhead is not needed, and is
5847 -- even incorrect when the call is a nested initialization call for a
5848 -- component whose expansion may generate adjust calls. However, if the
5849 -- call is some other procedure call within an initialization procedure
5850 -- (for example a call to Create_Task in the init_proc of the task
5851 -- run-time record) a transient scope must be created around this call.
5853 -- b) Enumeration literal pseudo-calls need no transient scope
5855 -- c) Intrinsic subprograms (Unchecked_Conversion and source info
5856 -- functions) do not use the secondary stack even though the return
5857 -- type may be unconstrained.
5859 -- d) Calls to a build-in-place function, since such functions may
5860 -- allocate their result directly in a target object, and cases where
5861 -- the result does get allocated in the secondary stack are checked for
5862 -- within the specialized Exp_Ch6 procedures for expanding those
5863 -- build-in-place calls.
5865 -- e) If the subprogram is marked Inline_Always, then even if it returns
5866 -- an unconstrained type the call does not require use of the secondary
5867 -- stack. However, inlining will only take place if the body to inline
5868 -- is already present. It may not be available if e.g. the subprogram is
5869 -- declared in a child instance.
5871 -- If this is an initialization call for a type whose construction
5872 -- uses the secondary stack, and it is not a nested call to initialize
5873 -- a component, we do need to create a transient scope for it. We
5874 -- check for this by traversing the type in Check_Initialization_Call.
5880 and then not Debug_Flag_Dot_K
5881 then
5888 and then Debug_Flag_Dot_K
5889 then
5895 then
5898 elsif Expander_Active
5901 and then
5903 or else
5905 then
5908 -- If the call appears within the bounds of a loop, it will
5909 -- be rewritten and reanalyzed, nothing left to do here.
5916 and then not Within_Init_Proc
5917 then
5921 -- A protected function cannot be called within the definition of the
5922 -- enclosing protected type.
5927 then
5928 Error_Msg_NE
5932 -- Propagate interpretation to actuals, and add default expressions
5933 -- where needed.
5938 -- Overloaded literals are rewritten as function calls, for purpose of
5939 -- resolution. After resolution, we can replace the call with the
5940 -- literal itself.
5946 -- Avoid validation, since it is a static function call
5952 -- If the subprogram is not global, then kill all saved values and
5953 -- checks. This is a bit conservative, since in many cases we could do
5954 -- better, but it is not worth the effort. Similarly, we kill constant
5955 -- values. However we do not need to do this for internal entities
5956 -- (unless they are inherited user-defined subprograms), since they
5957 -- are not in the business of molesting local values.
5959 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
5960 -- kill all checks and values for calls to global subprograms. This
5961 -- takes care of the case where an access to a local subprogram is
5962 -- taken, and could be passed directly or indirectly and then called
5963 -- from almost any context.
5965 -- Note: we do not do this step till after resolving the actuals. That
5966 -- way we still take advantage of the current value information while
5967 -- scanning the actuals.
5969 -- We suppress killing values if we are processing the nodes associated
5970 -- with N_Freeze_Entity nodes. Otherwise the declaration of a tagged
5971 -- type kills all the values as part of analyzing the code that
5972 -- initializes the dispatch tables.
5976 or else Suppress_Value_Tracking_On_Call
5981 then
5982 Kill_Current_Values;
5985 -- If we are warning about unread OUT parameters, this is the place to
5986 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
5987 -- after the above call to Kill_Current_Values (since that call clears
5988 -- the Last_Assignment field of all local variables).
5993 then
5994 declare
5998 begin
6008 then
6018 -- If the subprogram is a primitive operation, check whether or not
6019 -- it is a correct dispatching call.
6023 then
6028 and then not In_Instance
6029 then
6033 -- If this is a dispatching call, generate the appropriate reference,
6034 -- for better source navigation in GPS.
6038 then
6041 -- Normal case, not a dispatching call: generate a call reference
6043 else
6051 -- Check for violation of restriction No_Specific_Termination_Handlers
6052 -- and warn on a potentially blocking call to Abort_Task.
6056 or else
6058 then
6065 -- A call to Ada.Real_Time.Timing_Events.Set_Handler to set a relative
6066 -- timing event violates restriction No_Relative_Delay (AI-0211). We
6067 -- need to check the second argument to determine whether it is an
6068 -- absolute or relative timing event.
6073 then
6077 -- Issue an error for a call to an eliminated subprogram. This routine
6078 -- will not perform the check if the call appears within a default
6079 -- expression.
6083 -- In formal mode, the primitive operations of a tagged type or type
6084 -- extension do not include functions that return the tagged type.
6090 then
6094 -- Implement rule in 12.5.1 (23.3/2): In an instance, if the actual is
6095 -- class-wide and the call dispatches on result in a context that does
6096 -- not provide a tag, the call raises Program_Error.
6099 and then In_Instance
6104 then
6105 -- Verify that none of the formals are controlling
6107 declare
6111 begin
6133 -- Check the dimensions of the actuals in the call. For function calls,
6134 -- propagate the dimensions from the returned type to N.
6138 -- All done, evaluate call and deal with elaboration issues
6145 -----------------------------
6146 -- Resolve_Case_Expression --
6147 -----------------------------
6152 begin
6163 -------------------------------
6164 -- Resolve_Character_Literal --
6165 -------------------------------
6171 begin
6172 -- Verify that the character does belong to the type of the context
6177 -- Wide_Wide_Character literals must always be defined, since the set
6178 -- of wide wide character literals is complete, i.e. if a character
6179 -- literal is accepted by the parser, then it is OK for wide wide
6180 -- character (out of range character literals are rejected).
6185 -- Always accept character literal for type Any_Character, which
6186 -- occurs in error situations and in comparisons of literals, both
6187 -- of which should accept all literals.
6192 -- For Standard.Character or a type derived from it, check that the
6193 -- literal is in range.
6200 -- For Standard.Wide_Character or a type derived from it, check that the
6201 -- literal is in range.
6208 -- For Standard.Wide_Wide_Character or a type derived from it, we
6209 -- know the literal is in range, since the parser checked.
6214 -- If the entity is already set, this has already been resolved in a
6215 -- generic context, or comes from expansion. Nothing else to do.
6220 -- Otherwise we have a user defined character type, and we can use the
6221 -- standard visibility mechanisms to locate the referenced entity.
6223 else
6236 -- If we fall through, then the literal does not match any of the
6237 -- entries of the enumeration type. This isn't just a constraint error
6238 -- situation, it is an illegality (see RM 4.2).
6240 Error_Msg_NE
6244 ---------------------------
6245 -- Resolve_Comparison_Op --
6246 ---------------------------
6248 -- Context requires a boolean type, and plays no role in resolution.
6249 -- Processing identical to that for equality operators. The result type is
6250 -- the base type, which matters when pathological subtypes of booleans with
6251 -- limited ranges are used.
6258 begin
6259 -- If this is an intrinsic operation which is not predefined, use the
6260 -- types of its declared arguments to resolve the possibly overloaded
6261 -- operands. Otherwise the operands are unambiguous and specify the
6262 -- expected type.
6267 else
6278 -- Skip remaining processing if already set to Any_Type
6284 -- Deal with other error cases
6288 T = Any_Character
6289 then
6292 else
6300 -- Resolve the operands if types OK
6309 -- In SPARK, ordering operators <, <=, >, >= are not defined for Boolean
6310 -- types or array types except String.
6313 Check_SPARK_Restriction
6318 then
6319 Check_SPARK_Restriction
6323 -- Check comparison on unordered enumeration
6327 Error_Msg_NE
6332 -- Evaluate the relation (note we do this after the above check since
6333 -- this Eval call may change N to True/False.
6339 -----------------------------------------
6340 -- Resolve_Discrete_Subtype_Indication --
6341 -----------------------------------------
6343 procedure Resolve_Discrete_Subtype_Indication
6346 is
6350 begin
6358 else
6368 Error_Msg_NE
6371 -- Rewrite the constraint as a range of Typ
6372 -- to allow compilation to proceed further.
6384 else
6388 -- Additionally, we must check that the bounds are compatible
6389 -- with the given subtype, which might be different from the
6390 -- type of the context.
6394 -- ??? If the above check statically detects a Constraint_Error
6395 -- it replaces the offending bound(s) of the range R with a
6396 -- Constraint_Error node. When the itype which uses these bounds
6397 -- is frozen the resulting call to Duplicate_Subexpr generates
6398 -- a new temporary for the bounds.
6400 -- Unfortunately there are other itypes that are also made depend
6401 -- on these bounds, so when Duplicate_Subexpr is called they get
6402 -- a forward reference to the newly created temporaries and Gigi
6403 -- aborts on such forward references. This is probably sign of a
6404 -- more fundamental problem somewhere else in either the order of
6405 -- itype freezing or the way certain itypes are constructed.
6407 -- To get around this problem we call Remove_Side_Effects right
6408 -- away if either bounds of R are a Constraint_Error.
6410 declare
6414 begin
6430 -------------------------
6431 -- Resolve_Entity_Name --
6432 -------------------------
6434 -- Used to resolve identifiers and expanded names
6438 -- Denote whether an arbitrary node Nod appears in a check node
6440 ----------------------
6441 -- Appears_In_Check --
6442 ----------------------
6447 begin
6448 -- Climb the parent chain looking for a check node
6455 -- Prevent the search from going too far
6467 -- Local variables
6472 -- Start of processing for Resolve_Entity_Name
6474 begin
6475 -- If garbage from errors, set to Any_Type and return
6482 -- Replace named numbers by corresponding literals. Note that this is
6483 -- the one case where Resolve_Entity_Name must reset the Etype, since
6484 -- it is currently marked as universal.
6494 -- For enumeration literals, we need to make sure that a proper style
6495 -- check is done, since such literals are overloaded, and thus we did
6496 -- not do a style check during the first phase of analysis.
6502 -- Case of subtype name appearing as an operand in expression
6506 -- Allow use of subtype if it is a concurrent type where we are
6507 -- currently inside the body. This will eventually be expanded into a
6508 -- call to Self (for tasks) or _object (for protected objects). Any
6509 -- other use of a subtype is invalid.
6513 then
6516 -- Any other use is an error
6518 else
6519 Error_Msg_N
6523 -- Check discriminant use if entity is discriminant in current scope,
6524 -- i.e. discriminant of record or concurrent type currently being
6525 -- analyzed. Uses in corresponding body are unrestricted.
6530 then
6533 -- A parameterless generic function cannot appear in a context that
6534 -- requires resolution.
6545 then
6548 -- In all other cases, just do the possible static evaluation
6550 else
6551 -- A deferred constant that appears in an expression must have a
6552 -- completion, unless it has been removed by in-place expansion of
6553 -- an aggregate.
6559 and then not In_Spec_Expression
6561 then
6565 then
6567 else
6568 Error_Msg_N (
6576 -- A volatile object subject to enabled properties Async_Writers or
6577 -- Effective_Reads must appear in a specific context. The following
6578 -- checks are only relevant when SPARK_Mode is on as they are not
6579 -- standard Ada legality rules.
6584 and then
6587 then
6588 -- The volatile object can appear on either side of an assignment
6593 -- The volatile object is part of the initialization expression of
6594 -- another object. Ensure that the climb of the parent chain came
6595 -- from the expression side and not from the name side.
6600 then
6603 -- The volatile object appears as an actual parameter in a call to an
6604 -- instance of Unchecked_Conversion whose result is renamed.
6609 then
6612 -- Assume that references to volatile objects that appear as actual
6613 -- parameters in a procedure call are always legal. The full legality
6614 -- check is done when the actuals are resolved.
6619 -- Allow references to volatile objects in various checks
6624 else
6625 Error_Msg_N
6632 -------------------
6633 -- Resolve_Entry --
6634 -------------------
6646 -- If the bounds of the entry family being called depend on task
6647 -- discriminants, build a new index subtype where a discriminant is
6648 -- replaced with the value of the discriminant of the target task.
6649 -- The target task is the prefix of the entry name in the call.
6651 -----------------------
6652 -- Actual_Index_Type --
6653 -----------------------
6663 -- If the bound is given by a discriminant, replace with a reference
6664 -- to the discriminant of the same name in the target task. If the
6665 -- entry name is the target of a requeue statement and the entry is
6666 -- in the current protected object, the bound to be used is the
6667 -- discriminal of the object (see Apply_Range_Checks for details of
6668 -- the transformation).
6670 -----------------------------
6671 -- Actual_Discriminant_Ref --
6672 -----------------------------
6678 begin
6683 then
6689 then
6690 -- Note: here Bound denotes a discriminant of the corresponding
6691 -- record type tskV, whose discriminal is a formal of the
6692 -- init-proc tskVIP. What we want is the body discriminal,
6693 -- which is associated to the discriminant of the original
6694 -- concurrent type tsk.
6696 return New_Occurrence_Of
6699 else
6700 Ref :=
6710 -- Start of processing for Actual_Index_Type
6712 begin
6715 then
6718 else
6732 -- Start of processing of Resolve_Entry
6734 begin
6735 -- Find name of entry being called, and resolve prefix of name with its
6736 -- own type. The prefix can be overloaded, and the name and signature of
6737 -- the entry must be taken into account.
6741 -- Case of dealing with entry family within the current tasks
6745 else
6751 -- Entry call to an entry (or entry family) in the current task. This
6752 -- is legal even though the task will deadlock. Rewrite as call to
6753 -- current task.
6755 -- This can also be a call to an entry in an enclosing task. If this
6756 -- is a single task, we have to retrieve its name, because the scope
6757 -- of the entry is the task type, not the object. If the enclosing
6758 -- task is a task type, the identity of the task is given by its own
6759 -- self variable.
6761 -- Finally this can be a requeue on an entry of the same task or
6762 -- protected object.
6769 then
6770 -- S is an enclosing task or protected object. The concurrent
6771 -- declaration has been converted into a type declaration, and
6772 -- the object itself has an object declaration that follows
6773 -- the type in the same declarative part.
6785 -- Call to current task. Will be transformed into call to Self
6792 New_N :=
6795 Selector_Name =>
6802 then
6803 -- Use the entry name (which must be unique at this point) to find
6804 -- the prefix that returns the corresponding task/protected type.
6806 declare
6812 begin
6834 -- Up to this point the expression could have been the actual in a
6835 -- simple entry call, and be given by a named association.
6839 else
6845 ------------------------
6846 -- Resolve_Entry_Call --
6847 ------------------------
6859 begin
6860 -- We kill all checks here, because it does not seem worth the effort to
6861 -- do anything better, an entry call is a big operation.
6863 Kill_All_Checks;
6865 -- Processing of the name is similar for entry calls and protected
6866 -- operation calls. Once the entity is determined, we can complete
6867 -- the resolution of the actuals.
6869 -- The selector may be overloaded, in the case of a protected object
6870 -- with overloaded functions. The type of the context is used for
6871 -- resolution.
6876 then
6877 declare
6881 begin
6900 -- Simple entry call
6908 -- Call to member of entry family
6915 -- We cannot in general check the maximum depth of protected entry calls
6916 -- at compile time. But we can tell that any protected entry call at all
6917 -- violates a specified nesting depth of zero.
6923 -- Use context type to disambiguate a protected function that can be
6924 -- called without actuals and that returns an array type, and where the
6925 -- argument list may be an indexing of the returned value.
6930 and then
6936 and then
6937 Covers
6940 then
6941 declare
6944 begin
6945 Index_Node :=
6947 Prefix =>
6951 -- Since we are correcting a node classification error made by the
6952 -- parser, we call Replace rather than Rewrite.
6965 then
6966 -- Rewrite as call to the precondition wrapper, adding the task
6967 -- object to the list of actuals. If the call is to a member of an
6968 -- entry family, include the index as well.
6970 declare
6974 begin
6983 New_Call :=
6985 Name =>
6994 -- The operation name may have been overloaded. Order the actuals
6995 -- according to the formals of the resolved entity, and set the return
6996 -- type to that of the operation.
7007 -- Create a call reference to the entry
7015 -- Verify that a procedure call cannot masquerade as an entry
7016 -- call where an entry call is expected.
7021 then
7026 then
7031 then
7036 -- After resolution, entry calls and protected procedure calls are
7037 -- changed into entry calls, for expansion. The structure of the node
7038 -- does not change, so it can safely be done in place. Protected
7039 -- function calls must keep their structure because they are
7040 -- subexpressions.
7044 -- A protected operation that is not a function may modify the
7045 -- corresponding object, and cannot apply to a constant. If this
7046 -- is an internal call, the prefix is the type itself.
7052 then
7053 Error_Msg_N
7055 Entry_Name);
7069 -- Protected functions can return on the secondary stack, in which
7070 -- case we must trigger the transient scope mechanism.
7072 elsif Expander_Active
7074 then
7079 -------------------------
7080 -- Resolve_Equality_Op --
7081 -------------------------
7083 -- Both arguments must have the same type, and the boolean context does
7084 -- not participate in the resolution. The first pass verifies that the
7085 -- interpretation is not ambiguous, and the type of the left argument is
7086 -- correctly set, or is Any_Type in case of ambiguity. If both arguments
7087 -- are strings or aggregates, allocators, or Null, they are ambiguous even
7088 -- though they carry a single (universal) type. Diagnose this case here.
7096 -- The resolution rule for if expressions requires that each such must
7097 -- have a unique type. This means that if several dependent expressions
7098 -- are of a non-null anonymous access type, and the context does not
7099 -- impose an expected type (as can be the case in an equality operation)
7100 -- the expression must be rejected.
7103 -- Attempt to explain the nature of a redundant comparison with True. If
7104 -- the expression N is too complex, this routine issues a general error
7105 -- message.
7108 -- In the case of allocators and access attributes, the context must
7109 -- provide an indication of the specific access type to be used. If
7110 -- one operand is of such a "generic" access type, check whether there
7111 -- is a specific visible access type that has the same designated type.
7112 -- This is semantically dubious, and of no interest to any real code,
7113 -- but c48008a makes it all worthwhile.
7115 -------------------------
7116 -- Check_If_Expression --
7117 -------------------------
7123 begin
7130 then
7136 ------------------------
7137 -- Explain_Redundancy --
7138 ------------------------
7145 begin
7148 -- Strip the operand down to an entity
7150 loop
7153 else
7158 -- The construct denotes an entity
7163 -- Do not generate an error message when the comparison is done
7164 -- against the enumeration literal Standard.True.
7168 -- Build a customized error message
7195 -- The construct is too complex to disect, issue a general message
7197 else
7202 -----------------------------
7203 -- Find_Unique_Access_Type --
7204 -----------------------------
7211 begin
7213 E_Access_Attribute_Type)
7214 then
7218 E_Access_Attribute_Type)
7219 then
7221 else
7233 then
7246 -- Start of processing for Resolve_Equality_Op
7248 begin
7259 T = Any_Character
7260 then
7263 else
7272 then
7281 -- If expressions must have a single type, and if the context does
7282 -- not impose one the dependent expressions cannot be anonymous
7283 -- access types.
7285 -- Why no similar processing for case expressions???
7289 E_Anonymous_Access_Subprogram_Type)
7291 E_Anonymous_Access_Subprogram_Type)
7292 then
7300 -- In SPARK, equality operators = and /= for array types other than
7301 -- String are only defined when, for each index position, the
7302 -- operands have equal static bounds.
7306 -- Protect call to Matching_Static_Array_Bounds to avoid costly
7307 -- operation if not needed.
7315 then
7316 Check_SPARK_Restriction
7321 -- If the unique type is a class-wide type then it will be expanded
7322 -- into a dispatching call to the predefined primitive. Therefore we
7323 -- check here for potential violation of such restriction.
7329 if Warn_On_Redundant_Constructs
7334 then
7335 Error_Msg_N -- CODEFIX
7345 -- If this is an inequality, it may be the implicit inequality
7346 -- created for a user-defined operation, in which case the corres-
7347 -- ponding equality operation is not intrinsic, and the operation
7348 -- cannot be constant-folded. Else fold.
7353 or else Is_Intrinsic_Subprogram
7355 then
7361 then
7365 -- Ada 2005: If one operand is an anonymous access type, convert the
7366 -- other operand to it, to ensure that the underlying types match in
7367 -- the back-end. Same for access_to_subprogram, and the conversion
7368 -- verifies that the types are subtype conformant.
7370 -- We apply the same conversion in the case one of the operands is a
7371 -- private subtype of the type of the other.
7373 -- Why the Expander_Active test here ???
7375 if Expander_Active
7376 and then
7378 E_Anonymous_Access_Subprogram_Type)
7380 then
7400 ----------------------------------
7401 -- Resolve_Explicit_Dereference --
7402 ----------------------------------
7410 -- The candidate prefix type, if overloaded
7415 begin
7419 -- A useful optimization: check whether the dereference denotes an
7420 -- element of a container, and if so rewrite it as a call to the
7421 -- corresponding Element function.
7423 -- Disabled for now, on advice of ARG. A more restricted form of the
7424 -- predicate might be acceptable ???
7426 -- if Is_Container_Element (N) then
7427 -- return;
7428 -- end if;
7432 -- Use the context type to select the prefix that has the correct
7433 -- designated type. Keep the first match, which will be the inner-
7434 -- most.
7441 then
7446 -- Remove access types that do not match, but preserve access
7447 -- to subprogram interpretations, in case a further dereference
7448 -- is needed (see below).
7461 else
7462 -- If no interpretation covers the designated type of the prefix,
7463 -- this is the pathological case where not all implementations of
7464 -- the prefix allow the interpretation of the node as a call. Now
7465 -- that the expected type is known, Remove other interpretations
7466 -- from prefix, rewrite it as a call, and resolve again, so that
7467 -- the proper call node is generated.
7478 New_N :=
7480 Name =>
7491 -- If not overloaded, resolve P with its own type
7493 else
7501 -- If the designated type is a packed unconstrained array type, and the
7502 -- explicit dereference is not in the context of an attribute reference,
7503 -- then we must compute and set the actual subtype, since it is needed
7504 -- by Gigi. The reason we exclude the attribute case is that this is
7505 -- handled fine by Gigi, and in fact we use such attributes to build the
7506 -- actual subtype. We also exclude generated code (which builds actual
7507 -- subtypes directly if they are needed).
7514 then
7518 -- Note: No Eval processing is required for an explicit dereference,
7519 -- because such a name can never be static.
7523 -------------------------------------
7524 -- Resolve_Expression_With_Actions --
7525 -------------------------------------
7528 begin
7531 -- If N has no actions, and its expression has been constant folded,
7532 -- then rewrite N as just its expression. Note, we can't do this in
7533 -- the general case of Is_Empty_List (Actions (N)) as this would cause
7534 -- Expression (N) to be expanded again.
7538 then
7543 ----------------------------------
7544 -- Resolve_Generalized_Indexing --
7545 ----------------------------------
7553 begin
7554 -- In ASIS mode, propagate the information about the indices back to
7555 -- to the original indexing node. The generalized indexing is either
7556 -- a function call, or a dereference of one. The actuals include the
7557 -- prefix of the original node, which is the container expression.
7566 loop
7577 else
7583 ---------------------------
7584 -- Resolve_If_Expression --
7585 ---------------------------
7594 begin
7599 -- When the "then" expression is of a scalar subtype different from the
7600 -- result subtype, then insert a conversion to ensure the generation of
7601 -- a constraint check. The same is done for the else part below, again
7602 -- comparing subtypes rather than base types.
7606 then
7611 -- If ELSE expression present, just resolve using the determined type
7619 then
7624 -- If no ELSE expression is present, root type must be Standard.Boolean
7625 -- and we provide a Standard.True result converted to the appropriate
7626 -- Boolean type (in case it is a derived boolean type).
7629 Else_Expr :=
7634 else
7643 -------------------------------
7644 -- Resolve_Indexed_Component --
7645 -------------------------------
7653 begin
7661 -- Use the context type to select the prefix that yields the correct
7662 -- component type.
7664 declare
7671 begin
7678 and then
7679 Covers
7682 then
7691 else
7697 else
7708 else
7715 -- If prefix is access type, dereference to get real array type.
7716 -- Note: we do not apply an access check because the expander always
7717 -- introduces an explicit dereference, and the check will happen there.
7723 -- If name was overloaded, set component type correctly now
7724 -- If a misplaced call to an entry family (which has no index types)
7725 -- return. Error will be diagnosed from calling context.
7729 else
7736 -- The prefix may have resolved to a string literal, in which case its
7737 -- etype has a special representation. This is only possible currently
7738 -- if the prefix is a static concatenation, written in functional
7739 -- notation.
7744 else
7751 else
7762 -- Do not generate the warning on suspicious index if we are analyzing
7763 -- package Ada.Tags; otherwise we will report the warning with the
7764 -- Prims_Ptr field of the dispatch table.
7767 or else not
7769 Ada_Tags)
7770 then
7775 -- If the array type is atomic, and is packed, and we are in a left side
7776 -- context, then this is worth a warning, since we have a situation
7777 -- where the access to the component may cause extra read/writes of
7778 -- the atomic array object, which could be considered unexpected.
7786 then
7794 -----------------------------
7795 -- Resolve_Integer_Literal --
7796 -----------------------------
7799 begin
7804 --------------------------------
7805 -- Resolve_Intrinsic_Operator --
7806 --------------------------------
7816 -- If the operand is a literal, it cannot be the expression in a
7817 -- conversion. Use a qualified expression instead.
7822 begin
7824 Res :=
7830 else
7837 -- Start of processing for Resolve_Intrinsic_Operator
7839 begin
7840 -- We must preserve the original entity in a generic setting, so that
7841 -- the legality of the operation can be verified in an instance.
7856 -- If the result or operand types are private, rewrite with unchecked
7857 -- conversions on the operands and the result, to expose the proper
7858 -- underlying numeric type.
7863 then
7865 -- Unchecked_Convert_To (Btyp, Left_Opnd (N));
7866 -- What on earth is this commented out fragment of code???
7870 else
7891 then
7892 -- Add explicit conversion where needed, and save interpretations in
7893 -- case operands are overloaded. If the context is a VMS operation,
7894 -- assert that the conversion is legal (the operands have the proper
7895 -- types to select the VMS intrinsic). Note that in rare cases the
7896 -- VMS operators may be visible, but the default System is being used
7897 -- and Address is a private type.
7908 else
7918 else
7928 else
7933 --------------------------------------
7934 -- Resolve_Intrinsic_Unary_Operator --
7935 --------------------------------------
7937 procedure Resolve_Intrinsic_Unary_Operator
7940 is
7945 begin
7964 else
7969 ------------------------
7970 -- Resolve_Logical_Op --
7971 ------------------------
7976 begin
7979 -- Predefined operations on scalar types yield the base type. On the
7980 -- other hand, logical operations on arrays yield the type of the
7981 -- arguments (and the context).
7985 else
7989 -- OK if this is a VMS-specific intrinsic operation
7994 -- The following test is required because the operands of the operation
7995 -- may be literals, in which case the resulting type appears to be
7996 -- compatible with a signed integer type, when in fact it is compatible
7997 -- only with modular types. If the context itself is universal, the
7998 -- operation is illegal.
8006 Error_Msg_N
8014 then
8018 -- Replace AND by AND THEN, or OR by OR ELSE, if Short_Circuit_And_Or
8019 -- is active and the result type is standard Boolean (do not mess with
8020 -- ops that return a nonstandard Boolean type, because something strange
8021 -- is going on).
8023 -- Note: you might expect this replacement to be done during expansion,
8024 -- but that doesn't work, because when the pragma Short_Circuit_And_Or
8025 -- is used, no part of the right operand of an "and" or "or" operator
8026 -- should be executed if the left operand would short-circuit the
8027 -- evaluation of the corresponding "and then" or "or else". If we left
8028 -- the replacement to expansion time, then run-time checks associated
8029 -- with such operands would be evaluated unconditionally, due to being
8030 -- before the condition prior to the rewriting as short-circuit forms
8031 -- during expansion.
8033 if Short_Circuit_And_Or
8036 then
8044 -- Case of OR changed to OR ELSE
8046 else
8054 -- Return now, since analysis of the rewritten ops will take care of
8055 -- other reference bookkeeping and expression folding.
8070 -- In SPARK, logical operations AND, OR and XOR for arrays are defined
8071 -- only when both operands have same static lower and higher bounds. Of
8072 -- course the types have to match, so only check if operands are
8073 -- compatible and the node itself has no errors.
8077 then
8078 declare
8082 begin
8083 -- Protect call to Matching_Static_Array_Bounds to avoid costly
8084 -- operation if not needed.
8091 then
8092 Check_SPARK_Restriction
8101 ---------------------------
8102 -- Resolve_Membership_Op --
8103 ---------------------------
8105 -- The context can only be a boolean type, and does not determine the
8106 -- arguments. Arguments should be unambiguous, but the preference rule for
8107 -- universal types applies.
8117 -- Analysis has determined a unique type for the left operand. Use it to
8118 -- resolve the disjuncts.
8120 ----------------------------
8121 -- Resolve_Set_Membership --
8122 ----------------------------
8128 begin
8134 -- Alternative is an expression, a range
8135 -- or a subtype mark.
8139 then
8146 -- Check for duplicates for discrete case
8149 declare
8158 begin
8159 -- Loop checking duplicates. This is quadratic, but giant sets
8160 -- are unlikely in this context so it's a reasonable choice.
8167 N_Character_Literal)
8169 then
8187 -- Start of processing for Resolve_Membership_Op
8189 begin
8195 Resolve_Set_Membership;
8200 and then
8202 or else
8205 then
8208 -- Ada 2005 (AI-251): Support the following case:
8210 -- type I is interface;
8211 -- type T is tagged ...
8213 -- function Test (O : I'Class) is
8214 -- begin
8215 -- return O in T'Class.
8216 -- end Test;
8218 -- In this case we have nothing else to do. The membership test will be
8219 -- done at run time.
8226 then
8228 else
8232 -- If mixed-mode operations are present and operands are all literal,
8233 -- the only interpretation involves Duration, which is probably not
8234 -- the intention of the programmer.
8249 then
8255 else
8264 ------------------
8265 -- Resolve_Null --
8266 ------------------
8271 begin
8272 -- Handle restriction against anonymous null access values This
8273 -- restriction can be turned off using -gnatdj.
8275 -- Ada 2005 (AI-231): Remove restriction
8278 and then not Debug_Flag_J
8281 then
8282 -- In the common case of a call which uses an explicitly null value
8283 -- for an access parameter, give specialized error message.
8286 Error_Msg_N
8289 -- Standard message for all other cases (are there any?)
8291 else
8292 Error_Msg_N
8297 -- Ada 2005 (AI-231): Generate the null-excluding check in case of
8298 -- assignment to a null-excluding object
8303 then
8305 Insert_Action
8310 else
8317 -- In a distributed context, null for a remote access to subprogram may
8318 -- need to be replaced with a special record aggregate. In this case,
8319 -- return after having done the transformation.
8324 then
8328 -- The null literal takes its type from the context
8333 -----------------------
8334 -- Resolve_Op_Concat --
8335 -----------------------
8339 -- We wish to avoid deep recursion, because concatenations are often
8340 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
8341 -- operands nonrecursively until we find something that is not a simple
8342 -- concatenation (A in this case). We resolve that, and then walk back
8343 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
8344 -- to do the rest of the work at each level. The Parent pointers allow
8345 -- us to avoid recursion, and thus avoid running out of memory. See also
8346 -- Sem_Ch4.Analyze_Concatenation, where a similar approach is used.
8351 begin
8352 -- The following code is equivalent to:
8354 -- Resolve_Op_Concat_First (NN, Typ);
8355 -- Resolve_Op_Concat_Arg (N, ...);
8356 -- Resolve_Op_Concat_Rest (N, Typ);
8358 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
8359 -- operand is a concatenation.
8361 -- Walk down left operands
8363 loop
8372 -- Now (given the above example) NN is A&B and Op1 is A
8374 -- First resolve Op1 ...
8378 -- ... then walk NN back up until we reach N (where we started), calling
8379 -- Resolve_Op_Concat_Rest along the way.
8381 loop
8388 Check_SPARK_Restriction
8393 ---------------------------
8394 -- Resolve_Op_Concat_Arg --
8395 ---------------------------
8397 procedure Resolve_Op_Concat_Arg
8402 is
8406 begin
8408 if Is_Comp
8412 then
8414 else
8418 -- If both Array & Array and Array & Component are visible, there is a
8419 -- potential ambiguity that must be reported.
8424 then
8428 -- If the operation is user-defined and not overloaded use its
8429 -- profile. The operation may be a renaming, in which case it has
8430 -- been rewritten, and we want the original profile.
8435 then
8437 Etype
8441 -- Otherwise an aggregate may match both the array type and the
8442 -- component type.
8444 else
8449 else
8453 then
8454 declare
8459 begin
8464 -- Special-case the error message when the overloading is
8465 -- caused by a function that yields an array and can be
8466 -- called without parameters.
8471 Error_Msg_NE
8473 Error_Msg_NE
8477 else
8485 or else
8487 then
8488 Error_Msg_N -- CODEFIX
8506 else
8511 else
8515 -- Concatenation is restricted in SPARK: each operand must be either a
8516 -- string literal, the name of a string constant, a static character or
8517 -- string expression, or another concatenation. Arg cannot be a
8518 -- concatenation here as callers of Resolve_Op_Concat_Arg call it
8519 -- separately on each final operand, past concatenation operations.
8523 Check_SPARK_Restriction
8531 then
8532 Check_SPARK_Restriction
8536 -- Do not issue error on an operand that is neither a character nor a
8537 -- string, as the error is issued in Resolve_Op_Concat.
8539 else
8546 -----------------------------
8547 -- Resolve_Op_Concat_First --
8548 -----------------------------
8555 begin
8556 -- The parser folds an enormous sequence of concatenations of string
8557 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
8558 -- in the right operand. If the expression resolves to a predefined "&"
8559 -- operator, all is well. Otherwise, the parser's folding is wrong, so
8560 -- we give an error. See P_Simple_Expression in Par.Ch4.
8565 then
8580 ----------------------------
8581 -- Resolve_Op_Concat_Rest --
8582 ----------------------------
8588 begin
8597 -- If this is not a static concatenation, but the result is a string
8598 -- type (and not an array of strings) ensure that static string operands
8599 -- have their subtypes properly constructed.
8603 then
8609 ----------------------
8610 -- Resolve_Op_Expon --
8611 ----------------------
8616 begin
8617 -- Catch attempts to do fixed-point exponentiation with universal
8618 -- operands, which is a case where the illegality is not caught during
8619 -- normal operator analysis. This is not done in preanalysis mode
8620 -- since the tree is not fully decorated during preanalysis.
8631 then
8641 then
8648 then
8652 -- We do the resolution using the base type, because intermediate values
8653 -- in expressions are always of the base type, not a subtype of it.
8658 -- For integer types, right argument must be in Natural range
8673 -- Evaluate the exponentiation operator for dimensioned type
8676 else
8680 -- Set overflow checking bit. Much cleverer code needed here eventually
8681 -- and perhaps the Resolve routines should be separated for the various
8682 -- arithmetic operations, since they will need different processing. ???
8691 --------------------
8692 -- Resolve_Op_Not --
8693 --------------------
8699 -- This function determines if the parent node is a boolean operator or
8700 -- operation (comparison op, membership test, or short circuit form) and
8701 -- the not in question is the left operand of this operation. Note that
8702 -- if the not is in parens, then false is returned.
8704 -----------------------
8705 -- Parent_Is_Boolean --
8706 -----------------------
8709 begin
8713 else
8715 when N_Op_And |
8716 N_Op_Eq |
8717 N_Op_Ge |
8718 N_Op_Gt |
8719 N_Op_Le |
8720 N_Op_Lt |
8721 N_Op_Ne |
8722 N_Op_Or |
8723 N_Op_Xor |
8724 N_In |
8725 N_Not_In |
8726 N_And_Then |
8727 N_Or_Else =>
8737 -- Start of processing for Resolve_Op_Not
8739 begin
8740 -- Predefined operations on scalar types yield the base type. On the
8741 -- other hand, logical operations on arrays yield the type of the
8742 -- arguments (and the context).
8746 else
8753 -- Straightforward case of incorrect arguments
8760 -- Special case of probable missing parens
8764 Error_Msg_N
8767 else
8768 Error_Msg_N
8775 -- OK resolution of NOT
8777 else
8778 -- Warn if non-boolean types involved. This is a case like not a < b
8779 -- where a and b are modular, where we will get (not a) < b and most
8780 -- likely not (a < b) was intended.
8782 if Warn_On_Questionable_Missing_Parens
8784 and then Parent_Is_Boolean
8785 then
8789 -- Warn on double negation if checking redundant constructs
8791 if Warn_On_Redundant_Constructs
8796 then
8800 -- Complete resolution and evaluation of NOT
8810 -----------------------------
8811 -- Resolve_Operator_Symbol --
8812 -----------------------------
8814 -- Nothing to be done, all resolved already
8820 begin
8824 ----------------------------------
8825 -- Resolve_Qualified_Expression --
8826 ----------------------------------
8834 begin
8837 -- Protect call to Matching_Static_Array_Bounds to avoid costly
8838 -- operation if not needed.
8845 then
8846 Check_SPARK_Restriction
8850 -- A qualified expression requires an exact match of the type, class-
8851 -- wide matching is not allowed. However, if the qualifying type is
8852 -- specific and the expression has a class-wide type, it may still be
8853 -- okay, since it can be the result of the expansion of a call to a
8854 -- dispatching function, so we also have to check class-wideness of the
8855 -- type of the expression's original node.
8858 or else
8862 then
8866 -- If the target type is unconstrained, then we reset the type of the
8867 -- result from the type of the expression. For other cases, the actual
8868 -- subtype of the expression is the target type.
8872 then
8880 ------------------------------
8881 -- Resolve_Raise_Expression --
8882 ------------------------------
8885 begin
8889 else
8894 -------------------
8895 -- Resolve_Range --
8896 -------------------
8903 -- Returns True if N is of the form X'First .. X'Last where X is the
8904 -- same entity for both attributes.
8906 --------------------
8907 -- First_Last_Ref --
8908 --------------------
8914 begin
8919 then
8920 declare
8923 begin
8927 then
8936 -- Start of processing for Resolve_Range
8938 begin
8943 -- Check for inappropriate range on unordered enumeration type
8947 -- Exclude X'First .. X'Last if X is the same entity for both
8949 and then not First_Last_Ref
8950 then
8952 Error_Msg_NE
8959 -- We have to check the bounds for being within the base range as
8960 -- required for a non-static context. Normally this is automatic and
8961 -- done as part of evaluating expressions, but the N_Range node is an
8962 -- exception, since in GNAT we consider this node to be a subexpression,
8963 -- even though in Ada it is not. The circuit in Sem_Eval could check for
8964 -- this, but that would put the test on the main evaluation path for
8965 -- expressions.
8970 -- Check for an ambiguous range over character literals. This will
8971 -- happen with a membership test involving only literals.
8979 -- If bounds are static, constant-fold them, so size computations are
8980 -- identical between front-end and back-end. Do not perform this
8981 -- transformation while analyzing generic units, as type information
8982 -- would be lost when reanalyzing the constant node in the instance.
8995 --------------------------
8996 -- Resolve_Real_Literal --
8997 --------------------------
9002 begin
9003 -- Special processing for fixed-point literals to make sure that the
9004 -- value is an exact multiple of small where this is required. We skip
9005 -- this for the universal real case, and also for generic types.
9011 then
9012 declare
9019 begin
9020 -- Case of literal is not an exact multiple of the Small
9024 -- For a source program literal for a decimal fixed-point type,
9025 -- this is statically illegal (RM 4.9(36)).
9030 then
9034 -- Generate a warning if literal from source
9037 and then Warn_On_Bad_Fixed_Value
9038 then
9039 Error_Msg_N
9041 N);
9044 -- Replace literal by a value that is the exact representation
9045 -- of a value of the type, i.e. a multiple of the small value,
9046 -- by truncation, since Machine_Rounds is false for all GNAT
9047 -- fixed-point types (RM 4.9(38)).
9057 -- In all cases, set the corresponding integer field
9063 -- Now replace the actual type by the expected type as usual
9069 -----------------------
9070 -- Resolve_Reference --
9071 -----------------------
9076 begin
9077 -- Replace general access with specific type
9085 -- If we are taking the reference of a volatile entity, then treat it as
9086 -- a potential modification of this entity. This is too conservative,
9087 -- but necessary because remove side effects can cause transformations
9088 -- of normal assignments into reference sequences that otherwise fail to
9089 -- notice the modification.
9096 --------------------------------
9097 -- Resolve_Selected_Component --
9098 --------------------------------
9113 -- Check whether this is the initialization of a component within an
9114 -- init proc (by assignment or call to another init proc). If true,
9115 -- there is no need for a discriminant check.
9117 --------------------
9118 -- Init_Component --
9119 --------------------
9122 begin
9123 return Inside_Init_Proc
9129 -- Start of processing for Resolve_Selected_Component
9131 begin
9134 -- Use the context type to select the prefix that has a selector
9135 -- of the correct name and type.
9143 else
9147 -- Locate selected component. For a private prefix the selector
9148 -- can denote a discriminant.
9152 -- The visible components of a class-wide type are those of
9153 -- the root type.
9163 then
9170 else
9174 Error_Msg_N
9179 else
9182 -- There may be an implicit dereference. Retrieve
9183 -- designated record type.
9187 else
9193 -- Resolution chooses the new interpretation.
9194 -- Find the component with the right name.
9199 loop
9220 else
9221 -- Resolve prefix with its type
9226 -- Generate cross-reference. We needed to wait until full overloading
9227 -- resolution was complete to do this, since otherwise we can't tell if
9228 -- we are an lvalue or not.
9232 else
9236 -- If prefix is an access type, the node will be transformed into an
9237 -- explicit dereference during expansion. The type of the node is the
9238 -- designated type of that of the prefix.
9243 else
9247 -- Set flag for expander if discriminant check required
9254 and then not Init_Component
9255 then
9263 -- If the prefix is a record conversion, this may be a renamed
9264 -- discriminant whose bounds differ from those of the original
9265 -- one, so we must ensure that a range check is performed.
9270 then
9274 -- Note: No Eval processing is required, because the prefix is of a
9275 -- record type, or protected type, and neither can possibly be static.
9277 -- If the array type is atomic, and is packed, and we are in a left side
9278 -- context, then this is worth a warning, since we have a situation
9279 -- where the access to the component may cause extra read/writes of the
9280 -- atomic array object, which could be considered unexpected.
9288 then
9289 Error_Msg_N
9291 Error_Msg_N
9298 -------------------
9299 -- Resolve_Shift --
9300 -------------------
9307 begin
9308 -- We do the resolution using the base type, because intermediate values
9309 -- in expressions always are of the base type, not a subtype of it.
9322 ---------------------------
9323 -- Resolve_Short_Circuit --
9324 ---------------------------
9331 begin
9332 -- Ensure all actions associated with the left operand (e.g.
9333 -- finalization of transient controlled objects) are fully evaluated
9334 -- locally within an expression with actions. This is particularly
9335 -- helpful for coverage analysis. However this should not happen in
9336 -- generics.
9339 declare
9341 begin
9349 -- Set Comes_From_Source on L to preserve warnings for unset
9350 -- reference.
9359 -- Check for issuing warning for always False assert/check, this happens
9360 -- when assertions are turned off, in which case the pragma Assert/Check
9361 -- was transformed into:
9363 -- if False and then <condition> then ...
9365 -- and we detect this pattern
9367 if Warn_On_Assertion_Failure
9374 then
9375 declare
9378 begin
9379 -- Special handling of Asssert pragma
9383 then
9384 declare
9386 Original_Node
9387 (Expression
9390 begin
9391 -- Don't warn if original condition is explicit False,
9392 -- since obviously the failure is expected in this case.
9396 then
9399 -- Issue warning. We do not want the deletion of the
9400 -- IF/AND-THEN to take this message with it. We achieve this
9401 -- by making sure that the expanded code points to the Sloc
9402 -- of the expression, not the original pragma.
9404 else
9405 -- Note: Use Error_Msg_F here rather than Error_Msg_N.
9406 -- The source location of the expression is not usually
9407 -- the best choice here. For example, it gets located on
9408 -- the last AND keyword in a chain of boolean expressiond
9409 -- AND'ed together. It is best to put the message on the
9410 -- first character of the assertion, which is the effect
9411 -- of the First_Node call here.
9413 Error_Msg_F
9415 Expression
9420 -- Similar processing for Check pragma
9424 then
9425 -- Don't want to warn if original condition is explicit False
9427 declare
9429 Original_Node
9430 (Expression
9432 begin
9435 then
9438 -- Post warning
9440 else
9441 -- Again use Error_Msg_F rather than Error_Msg_N, see
9442 -- comment above for an explanation of why we do this.
9444 Error_Msg_F
9446 Expression
9454 -- Continue with processing of short circuit
9463 -------------------
9464 -- Resolve_Slice --
9465 -------------------
9474 begin
9477 -- Use the context type to select the prefix that yields the correct
9478 -- array type.
9480 declare
9487 begin
9495 then
9503 else
9508 else
9519 else
9529 -- If the prefix is an access to an unconstrained array, we must use
9530 -- the actual subtype of the object to perform the index checks. The
9531 -- object denoted by the prefix is implicit in the node, so we build
9532 -- an explicit representation for it in order to compute the actual
9533 -- subtype.
9538 declare
9542 begin
9553 then
9556 -- If the name is a selected component that depends on discriminants,
9557 -- build an actual subtype for it. This can happen only when the name
9558 -- itself is overloaded; otherwise the actual subtype is created when
9559 -- the selected component is analyzed.
9562 and then Full_Analysis
9564 then
9565 declare
9568 begin
9573 -- Maybe this should just be "else", instead of checking for the
9574 -- specific case of slice??? This is needed for the case where the
9575 -- prefix is an Image attribute, which gets expanded to a slice, and so
9576 -- has a constrained subtype which we want to use for the slice range
9577 -- check applied below (the range check won't get done if the
9578 -- unconstrained subtype of the 'Image is used).
9584 -- Obtain the type of the array index
9588 else
9592 -- If name was overloaded, set slice type correctly now
9596 -- Handle the generation of a range check that compares the array index
9597 -- against the discrete_range. The check is not applied to internally
9598 -- built nodes associated with the expansion of dispatch tables. Check
9599 -- that Ada.Tags has already been loaded to avoid extra dependencies on
9600 -- the unit.
9602 if Tagged_Type_Expansion
9608 then
9611 -- The discrete_range is specified by a subtype indication. Create a
9612 -- shallow copy and inherit the type, parent and source location from
9613 -- the discrete_range. This ensures that the range check is inserted
9614 -- relative to the slice and that the runtime exception points to the
9615 -- proper construct.
9624 -- The discrete_range is a regular range. Resolve the bounds and remove
9625 -- their side effects.
9627 else
9644 -- Check bad use of type with predicates
9647 Bad_Predicated_Subtype_Use
9651 -- Otherwise here is where we check suspicious indexes
9662 ----------------------------
9663 -- Resolve_String_Literal --
9664 ----------------------------
9675 begin
9676 -- For a string appearing in a concatenation, defer creation of the
9677 -- string_literal_subtype until the end of the resolution of the
9678 -- concatenation, because the literal may be constant-folded away. This
9679 -- is a useful optimization for long concatenation expressions.
9681 -- If the string is an aggregate built for a single character (which
9682 -- happens in a non-static context) or a is null string to which special
9683 -- checks may apply, we build the subtype. Wide strings must also get a
9684 -- string subtype if they come from a one character aggregate. Strings
9685 -- generated by attributes might be static, but it is often hard to
9686 -- determine whether the enclosing context is static, so we generate
9687 -- subtypes for them as well, thus losing some rarer optimizations ???
9688 -- Same for strings that come from a static conversion.
9690 Need_Check :=
9699 -- If the resolving type is itself a string literal subtype, we can just
9700 -- reuse it, since there is no point in creating another.
9706 and then not Need_Check
9708 N_Attribute_Reference,
9709 N_Qualified_Expression,
9710 N_Type_Conversion)
9711 then
9714 -- Otherwise we must create a string literal subtype. Note that the
9715 -- whole idea of string literal subtypes is simply to avoid the need
9716 -- for building a full fledged array subtype for each literal.
9718 else
9724 or else Need_Check
9725 then
9732 then
9738 -- The validity of a null string has been checked in the call to
9739 -- Eval_String_Literal.
9744 -- Always accept string literal with component type Any_Character, which
9745 -- occurs in error situations and in comparisons of literals, both of
9746 -- which should accept all literals.
9751 -- If the type is bit-packed, then we always transform the string
9752 -- literal into a full fledged aggregate.
9757 -- Deal with cases of Wide_Wide_String, Wide_String, and String
9759 else
9760 -- For Standard.Wide_Wide_String, or any other type whose component
9761 -- type is Standard.Wide_Wide_Character, we know that all the
9762 -- characters in the string must be acceptable, since the parser
9763 -- accepted the characters as valid character literals.
9768 -- For the case of Standard.String, or any other type whose component
9769 -- type is Standard.Character, we must make sure that there are no
9770 -- wide characters in the string, i.e. that it is entirely composed
9771 -- of characters in range of type Character.
9773 -- If the string literal is the result of a static concatenation, the
9774 -- test has already been performed on the components, and need not be
9775 -- repeated.
9779 then
9783 -- If we are out of range, post error. This is one of the
9784 -- very few places that we place the flag in the middle of
9785 -- a token, right under the offending wide character. Not
9786 -- quite clear if this is right wrt wide character encoding
9787 -- sequences, but it's only an error message.
9789 Error_Msg
9796 -- For the case of Standard.Wide_String, or any other type whose
9797 -- component type is Standard.Wide_Character, we must make sure that
9798 -- there are no wide characters in the string, i.e. that it is
9799 -- entirely composed of characters in range of type Wide_Character.
9801 -- If the string literal is the result of a static concatenation,
9802 -- the test has already been performed on the components, and need
9803 -- not be repeated.
9807 then
9811 -- If we are out of range, post error. This is one of the
9812 -- very few places that we place the flag in the middle of
9813 -- a token, right under the offending wide character.
9815 -- This is not quite right, because characters in general
9816 -- will take more than one character position ???
9818 Error_Msg
9825 -- If the root type is not a standard character, then we will convert
9826 -- the string into an aggregate and will let the aggregate code do
9827 -- the checking. Standard Wide_Wide_Character is also OK here.
9829 else
9833 -- See if the component type of the array corresponding to the string
9834 -- has compile time known bounds. If yes we can directly check
9835 -- whether the evaluation of the string will raise constraint error.
9836 -- Otherwise we need to transform the string literal into the
9837 -- corresponding character aggregate and let the aggregate code do
9838 -- the checking.
9842 -- Check for the case of full range, where we are definitely OK
9848 -- Here the range is not the complete base type range, so check
9850 declare
9858 begin
9861 then
9867 then
9868 Apply_Compile_Time_Constraint_Error
9870 CE_Range_Check_Failed,
9881 -- If we got here we meed to transform the string literal into the
9882 -- equivalent qualified positional array aggregate. This is rather
9883 -- heavy artillery for this situation, but it is hard work to avoid.
9885 declare
9890 begin
9891 -- Build the character literals, we give them source locations that
9892 -- correspond to the string positions, which is a bit tricky given
9893 -- the possible presence of wide character escape sequences.
9907 -- Should we have a call to Skip_Wide here ???
9909 -- ??? else
9910 -- Skip_Wide (P);
9918 Expression =>
9925 -----------------------------
9926 -- Resolve_Type_Conversion --
9927 -----------------------------
9939 -- Set to False to suppress cases where we want to suppress the test
9940 -- for redundancy to avoid possible false positives on this warning.
9942 begin
9943 if not Conv_OK
9945 then
9949 -- If the Operand Etype is Universal_Fixed, then the conversion is
9950 -- never redundant. We need this check because by the time we have
9951 -- finished the rather complex transformation, the conversion looks
9952 -- redundant when it is not.
9957 -- If the operand is marked as Any_Fixed, then special processing is
9958 -- required. This is also a case where we suppress the test for a
9959 -- redundant conversion, since most certainly it is not redundant.
9964 -- Mixed-mode operation involving a literal. Context must be a fixed
9965 -- type which is applied to the literal subsequently.
9973 or else
9975 then
9976 -- Return if expression is ambiguous
9981 -- If nothing else, the available fixed type is Duration
9983 else
9987 -- Resolve the real operand with largest available precision
9991 else
9997 -- If the operand is a literal (it could be a non-static and
9998 -- illegal exponentiation) check whether the use of Duration
9999 -- is potentially inaccurate.
10004 then
10005 Error_Msg_N
10008 Error_Msg_N
10015 then
10018 else
10027 -- In SPARK, a type conversion between array types should be restricted
10028 -- to types which have matching static bounds.
10030 -- Protect call to Matching_Static_Array_Bounds to avoid costly
10031 -- operation if not needed.
10038 then
10039 Check_SPARK_Restriction
10043 -- In formal mode, the operand of an ancestor type conversion must be an
10044 -- object (not an expression).
10052 then
10058 -- Note: we do the Eval_Type_Conversion call before applying the
10059 -- required checks for a subtype conversion. This is important, since
10060 -- both are prepared under certain circumstances to change the type
10061 -- conversion to a constraint error node, but in the case of
10062 -- Eval_Type_Conversion this may reflect an illegality in the static
10063 -- case, and we would miss the illegality (getting only a warning
10064 -- message), if we applied the type conversion checks first.
10068 -- Even when evaluation is not possible, we may be able to simplify the
10069 -- conversion or its expression. This needs to be done before applying
10070 -- checks, since otherwise the checks may use the original expression
10071 -- and defeat the simplifications. This is specifically the case for
10072 -- elimination of the floating-point Truncation attribute in
10073 -- float-to-int conversions.
10077 -- If after evaluation we still have a type conversion, then we may need
10078 -- to apply checks required for a subtype conversion.
10080 -- Skip these type conversion checks if universal fixed operands
10081 -- operands involved, since range checks are handled separately for
10082 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
10088 then
10092 -- Issue warning for conversion of simple object to its own type. We
10093 -- have to test the original nodes, since they may have been rewritten
10094 -- by various optimizations.
10098 -- Here we test for a redundant conversion if the warning mode is
10099 -- active (and was not locally reset), and we have a type conversion
10100 -- from source not appearing in a generic instance.
10102 if Test_Redundant
10105 and then not In_Instance
10106 then
10110 -- If the node is part of a larger expression, the Target_Type
10111 -- may not be the original type of the node if the context is a
10112 -- condition. Recover original type to see if conversion is needed.
10116 then
10120 -- If we have an entity name, then give the warning if the entity
10121 -- is the right type, or if it is a loop parameter covered by the
10122 -- original type (that's needed because loop parameters have an
10123 -- odd subtype coming from the bounds).
10126 and then
10128 or else
10132 -- If not an entity, then type of expression must match
10135 then
10136 -- One more check, do not give warning if the analyzed conversion
10137 -- has an expression with non-static bounds, and the bounds of the
10138 -- target are static. This avoids junk warnings in cases where the
10139 -- conversion is necessary to establish staticness, for example in
10140 -- a case statement.
10144 then
10147 -- Finally, if this type conversion occurs in a context requiring
10148 -- a prefix, and the expression is a qualified expression then the
10149 -- type conversion is not redundant, since a qualified expression
10150 -- is not a prefix, whereas a type conversion is. For example, "X
10151 -- := T'(Funx(...)).Y;" is illegal because a selected component
10152 -- requires a prefix, but a type conversion makes it legal: "X :=
10153 -- T(T'(Funx(...))).Y;"
10155 -- In Ada 2012, a qualified expression is a name, so this idiom is
10156 -- no longer needed, but we still suppress the warning because it
10157 -- seems unfriendly for warnings to pop up when you switch to the
10158 -- newer language version.
10162 N_Indexed_Component,
10163 N_Selected_Component,
10164 N_Slice,
10165 N_Explicit_Dereference)
10166 then
10169 -- Never warn on conversion to Long_Long_Integer'Base since
10170 -- that is most likely an artifact of the extended overflow
10171 -- checking and comes from complex expanded code.
10176 -- Here we give the redundant conversion warning. If it is an
10177 -- entity, give the name of the entity in the message. If not,
10178 -- just mention the expression.
10180 -- Shoudn't we test Warn_On_Redundant_Constructs here ???
10182 else
10185 Error_Msg_NE -- CODEFIX
10188 else
10189 Error_Msg_NE
10197 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
10198 -- No need to perform any interface conversion if the type of the
10199 -- expression coincides with the target type.
10202 and then Expander_Active
10204 then
10205 declare
10209 begin
10221 -- Conversion from interface type
10225 -- Ada 2005 (AI-217): Handle entities from limited views
10229 Error_Msg_NE -- CODEFIX
10232 Error_Msg_N
10234 N);
10237 and then not
10240 then
10242 Error_Msg_NE -- CODEFIX
10245 Error_Msg_N
10247 N);
10249 else
10253 -- Conversion to interface type
10257 -- Handle subtypes
10264 or else Interface_Present_In_Ancestor
10267 then
10269 else
10272 Error_Msg_N
10280 -- Ada 2012: if target type has predicates, the result requires a
10281 -- predicate check. If the context is a call to another predicate
10282 -- check we must prevent infinite recursion.
10288 or else
10290 then
10293 else
10299 ----------------------
10300 -- Resolve_Unary_Op --
10301 ----------------------
10310 begin
10313 Check_SPARK_Restriction
10317 -- Deal with intrinsic unary operators
10323 then
10328 -- Deal with universal cases
10331 or else
10333 then
10340 -- Generate warning for expressions like abs (x mod 2)
10342 if Warn_On_Redundant_Constructs
10344 then
10348 Error_Msg_N -- CODEFIX
10353 -- Deal with reference generation
10360 -- Set overflow checking bit. Much cleverer code needed here eventually
10361 -- and perhaps the Resolve routines should be separated for the various
10362 -- arithmetic operations, since they will need different processing ???
10370 -- Generate warning for expressions like -5 mod 3 for integers. No need
10371 -- to worry in the floating-point case, since parens do not affect the
10372 -- result so there is no point in giving in a warning.
10374 declare
10383 begin
10384 if Warn_On_Questionable_Missing_Parens
10388 then
10391 -- We are looking for cases where the right operand is not
10392 -- parenthesized, and is a binary operator, multiply, divide, or
10393 -- mod. These are the cases where the grouping can affect results.
10397 then
10398 -- For mod, we always give the warning, since the value is
10399 -- affected by the parenthesization (e.g. (-5) mod 315 /=
10400 -- -(5 mod 315)). But for the other cases, the only concern is
10401 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
10402 -- overflows, but (-2) * 64 does not). So we try to give the
10403 -- message only when overflow is possible.
10407 then
10412 else
10418 else
10422 -- Note that the test below is deliberately excluding the
10423 -- largest negative number, since that is a potentially
10424 -- troublesome case (e.g. -2 * x, where the result is the
10425 -- largest negative integer has an overflow with 2 * x).
10432 -- For the multiplication case, the only case we have to worry
10433 -- about is when (-a)*b is exactly the largest negative number
10434 -- so that -(a*b) can cause overflow. This can only happen if
10435 -- a is a power of 2, and more generally if any operand is a
10436 -- constant that is not a power of 2, then the parentheses
10437 -- cannot affect whether overflow occurs. We only bother to
10438 -- test the left most operand
10440 -- Loop looking at left operands for one that has known value
10447 -- Operand value of 0 or 1 skips warning
10452 -- Otherwise check power of 2, if power of 2, warn, if
10453 -- anything else, skip warning.
10455 else
10459 else
10468 -- Keep looking at left operands
10473 -- For rem or "/" we can only have a problematic situation
10474 -- if the divisor has a value of minus one or one. Otherwise
10475 -- overflow is impossible (divisor > 1) or we have a case of
10476 -- division by zero in any case.
10481 then
10485 -- If we fall through warning should be issued
10487 -- Shouldn't we test Warn_On_Questionable_Missing_Parens ???
10489 Error_Msg_N
10496 ----------------------------------
10497 -- Resolve_Unchecked_Expression --
10498 ----------------------------------
10500 procedure Resolve_Unchecked_Expression
10503 is
10504 begin
10509 ---------------------------------------
10510 -- Resolve_Unchecked_Type_Conversion --
10511 ---------------------------------------
10513 procedure Resolve_Unchecked_Type_Conversion
10516 is
10522 begin
10523 -- Resolve operand using its own type
10530 ------------------------------
10531 -- Rewrite_Operator_As_Call --
10532 ------------------------------
10539 begin
10546 New_N :=
10557 ------------------------------
10558 -- Rewrite_Renamed_Operator --
10559 ------------------------------
10561 procedure Rewrite_Renamed_Operator
10565 is
10570 begin
10571 -- Do not perform this transformation within a pre/postcondition,
10572 -- because the expression will be re-analyzed, and the transformation
10573 -- might affect the visibility of the operator, e.g. in an instance.
10579 -- Rewrite the operator node using the real operator, not its renaming.
10580 -- Exclude user-defined intrinsic operations of the same name, which are
10581 -- treated separately and rewritten as calls.
10590 -- Indicate that both the original entity and its renaming are
10591 -- referenced at this point.
10602 -- If the context type is private, add the appropriate conversions so
10603 -- that the operator is applied to the full view. This is done in the
10604 -- routines that resolve intrinsic operators.
10608 then
10610 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
10611 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
10624 -- Operator renames a user-defined operator of the same name. Use the
10625 -- original operator in the node, which is the one Gigi knows about.
10632 -----------------------
10633 -- Set_Slice_Subtype --
10634 -----------------------
10636 -- Build an implicit subtype declaration to represent the type delivered by
10637 -- the slice. This is an abbreviated version of an array subtype. We define
10638 -- an index subtype for the slice, using either the subtype name or the
10639 -- discrete range of the slice. To be consistent with index usage elsewhere
10640 -- we create a list header to hold the single index. This list is not
10641 -- otherwise attached to the syntax tree.
10652 begin
10658 else
10659 -- We force the evaluation of a range. This is definitely needed in
10660 -- the renamed case, and seems safer to do unconditionally. Note in
10661 -- any case that since we will create and insert an Itype referring
10662 -- to this range, we must make sure any side effect removal actions
10663 -- are inserted before the Itype definition.
10669 -- If the discrete range is given by a subtype indication, the
10670 -- type of the slice is the base of the subtype mark.
10673 declare
10675 begin
10684 -- Take a new copy of Drange (where bounds have been rewritten to
10685 -- reference side-effect-free names). Using a separate tree ensures
10686 -- that further expansion (e.g. while rewriting a slice assignment
10687 -- into a FOR loop) does not attempt to remove side effects on the
10688 -- bounds again (which would cause the bounds in the index subtype
10689 -- definition to refer to temporaries before they are defined) (the
10690 -- reason is that some names are considered side effect free here
10691 -- for the subtype, but not in the context of a loop iteration
10692 -- scheme).
10713 -- The Etype of the existing Slice node is reset to this slice subtype.
10714 -- Its bounds are obtained from its first index.
10718 -- For packed slice subtypes, freeze immediately (except in the case of
10719 -- being in a "spec expression" where we never freeze when we first see
10720 -- the expression).
10725 -- For all other cases insert an itype reference in the slice's actions
10726 -- so that the itype is frozen at the proper place in the tree (i.e. at
10727 -- the point where actions for the slice are analyzed). Note that this
10728 -- is different from freezing the itype immediately, which might be
10729 -- premature (e.g. if the slice is within a transient scope). This needs
10730 -- to be done only if expansion is enabled.
10737 --------------------------------
10738 -- Set_String_Literal_Subtype --
10739 --------------------------------
10747 begin
10759 -- The low bound is set from the low bound of the corresponding index
10760 -- type. Note that we do not store the high bound in the string literal
10761 -- subtype, but it can be deduced if necessary from the length and the
10762 -- low bound.
10767 -- If the lower bound is not static we create a range for the string
10768 -- literal, using the index type and the known length of the literal.
10769 -- The index type is not necessarily Positive, so the upper bound is
10770 -- computed as T'Val (T'Pos (Low_Bound) + L - 1).
10772 else
10773 declare
10779 Prefix =>
10783 Left_Opnd =>
10786 Prefix =>
10788 Expressions =>
10790 Right_Opnd =>
10799 begin
10801 Set_String_Literal_Low_Bound
10804 else
10805 -- If the index type is an enumeration type, build bounds
10806 -- expression with attributes.
10808 Set_String_Literal_Low_Bound
10812 Prefix =>
10819 -- Build bona fide subtype for the string, and wrap it in an
10820 -- unchecked conversion, because the backend expects the
10821 -- String_Literal_Subtype to have a static lower bound.
10823 Index_Subtype :=
10830 -- In the context, the Index_Type may already have a constraint,
10831 -- so use common base type on string subtype. The base type may
10832 -- be used when generating attributes of the string, for example
10833 -- in the context of a slice assignment.
10858 ------------------------------
10859 -- Simplify_Type_Conversion --
10860 ------------------------------
10863 begin
10865 declare
10870 begin
10872 and then
10879 -- Special processing required if the conversion is the expression
10880 -- of a Truncation attribute reference. In this case we replace:
10882 -- ityp (ftyp'Truncation (x))
10884 -- by
10886 -- ityp (x)
10888 -- with the Float_Truncate flag set, which is more efficient.
10890 then
10899 -----------------------------
10900 -- Unique_Fixed_Point_Type --
10901 -----------------------------
10910 -- Give error messages for true ambiguity. Messages are posted on node
10911 -- N, and entities T1, T2 are the possible interpretations.
10913 -----------------------
10914 -- Fixed_Point_Error --
10915 -----------------------
10918 begin
10924 -- Start of processing for Unique_Fixed_Point_Type
10926 begin
10927 -- The operations on Duration are visible, so Duration is always a
10928 -- possible interpretation.
10932 -- Look for fixed-point types in enclosing scopes
10941 then
10943 Fixed_Point_Error;
10945 else
10956 -- Look for visible fixed type declarations in the context
10967 then
10969 Fixed_Point_Error;
10971 else
10984 Error_Msg_NE
10986 else
10987 Error_Msg_NE
10994 ----------------------
10995 -- Valid_Conversion --
10996 ----------------------
10998 function Valid_Conversion
11003 is
11008 function Conversion_Check
11011 -- Little routine to post Msg if Valid is False, returns Valid value
11014 -- If Report_Errs, then calls Errout.Error_Msg_N with its arguments
11016 procedure Conversion_Error_NE
11020 -- If Report_Errs, then calls Errout.Error_Msg_NE with its arguments
11022 function Valid_Tagged_Conversion
11025 -- Specifically test for validity of tagged conversions
11028 -- Check index and component conformance, and accessibility levels if
11029 -- the component types are anonymous access types (Ada 2005).
11031 ----------------------
11032 -- Conversion_Check --
11033 ----------------------
11035 function Conversion_Check
11038 is
11039 begin
11040 if not Valid
11042 -- A generic unit has already been analyzed and we have verified
11043 -- that a particular conversion is OK in that context. Since the
11044 -- instance is reanalyzed without relying on the relationships
11045 -- established during the analysis of the generic, it is possible
11046 -- to end up with inconsistent views of private types. Do not emit
11047 -- the error message in such cases. The rest of the machinery in
11048 -- Valid_Conversion still ensures the proper compatibility of
11049 -- target and operand types.
11051 and then not In_Instance
11052 then
11059 ------------------------
11060 -- Conversion_Error_N --
11061 ------------------------
11064 begin
11070 -------------------------
11071 -- Conversion_Error_NE --
11072 -------------------------
11074 procedure Conversion_Error_NE
11078 is
11079 begin
11085 ----------------------------
11086 -- Valid_Array_Conversion --
11087 ----------------------------
11090 is
11105 begin
11106 -- Error if wrong number of dimensions
11108 if
11110 then
11111 Conversion_Error_N
11115 -- Number of dimensions matches
11117 else
11118 -- Loop through indexes of the two arrays
11126 -- Error if index types are incompatible
11132 then
11133 Conversion_Error_N
11135 Operand);
11143 -- If component types have same base type, all set
11148 -- Here if base types of components are not the same. The only
11149 -- time this is allowed is if we have anonymous access types.
11151 -- The conversion of arrays of anonymous access types can lead
11152 -- to dangling pointers. AI-392 formalizes the accessibility
11153 -- checks that must be applied to such conversions to prevent
11154 -- out-of-scope references.
11156 elsif Ekind_In
11158 E_Anonymous_Access_Subprogram_Type)
11160 and then
11162 then
11165 then
11168 Conversion_Error_N
11178 -- Conversion not allowed because of accessibility levels
11180 else
11181 Conversion_Error_N
11187 else
11191 -- All other cases where component base types do not match
11193 else
11194 Conversion_Error_N
11196 Operand);
11200 -- Check that component subtypes statically match. For numeric
11201 -- types this means that both must be either constrained or
11202 -- unconstrained. For enumeration types the bounds must match.
11203 -- All of this is checked in Subtypes_Statically_Match.
11205 if not Subtypes_Statically_Match
11207 then
11208 Conversion_Error_N
11217 -----------------------------
11218 -- Valid_Tagged_Conversion --
11219 -----------------------------
11221 function Valid_Tagged_Conversion
11224 is
11225 begin
11226 -- Upward conversions are allowed (RM 4.6(22))
11230 then
11233 -- Downward conversion are allowed if the operand is class-wide
11234 -- (RM 4.6(23)).
11238 then
11243 then
11244 return
11248 -- Ada 2005 (AI-251): The conversion to/from interface types is
11249 -- always valid
11254 -- If the operand is a class-wide type obtained through a limited_
11255 -- with clause, and the context includes the non-limited view, use
11256 -- it to determine whether the conversion is legal.
11262 then
11267 then
11270 else
11271 Conversion_Error_NE
11278 -- Start of processing for Valid_Conversion
11280 begin
11284 declare
11292 begin
11293 -- Remove procedure calls, which syntactically cannot appear in
11294 -- this context, but which cannot be removed by type checking,
11295 -- because the context does not impose a type.
11297 -- When compiling for VMS, spurious ambiguities can be produced
11298 -- when arithmetic operations have a literal operand and return
11299 -- System.Address or a descendant of it. These ambiguities are
11300 -- otherwise resolved by the context, but for conversions there
11301 -- is no context type and the removal of the spurious operations
11302 -- must be done explicitly here.
11304 -- The node may be labelled overloaded, but still contain only one
11305 -- interpretation because others were discarded earlier. If this
11306 -- is the case, retain the single interpretation if legal.
11314 then
11315 -- More than one candidate interpretation is available
11325 then
11350 Conversion_Error_N
11353 -- If the interpretation involves a standard operator, use
11354 -- the location of the type, which may be user-defined.
11358 else
11362 Conversion_Error_N -- CODEFIX
11367 else
11371 Conversion_Error_N -- CODEFIX
11383 -- Deal with conversion of integer type to address if the pragma
11384 -- Allow_Integer_Address is in effect. We convert the conversion to
11385 -- an unchecked conversion in this case and we are all done.
11393 -- If we are within a child unit, check whether the type of the
11394 -- expression has an ancestor in a parent unit, in which case it
11395 -- belongs to its derivation class even if the ancestor is private.
11396 -- See RM 7.3.1 (5.2/3).
11400 -- Numeric types
11404 -- A universal fixed expression can be converted to any numeric type
11409 -- Also no need to check when in an instance or inlined body, because
11410 -- the legality has been established when the template was analyzed.
11411 -- Furthermore, numeric conversions may occur where only a private
11412 -- view of the operand type is visible at the instantiation point.
11413 -- This results in a spurious error if we check that the operand type
11414 -- is a numeric type.
11416 -- Note: in a previous version of this unit, the following tests were
11417 -- applied only for generated code (Comes_From_Source set to False),
11418 -- but in fact the test is required for source code as well, since
11419 -- this situation can arise in source code.
11424 -- Otherwise we need the conversion check
11426 else
11427 return Conversion_Check
11429 or else
11435 -- Array types
11441 then
11442 Conversion_Error_N
11446 else
11450 -- Ada 2005 (AI-251): Anonymous access types where target references an
11451 -- interface type.
11454 E_Anonymous_Access_Type)
11456 then
11457 -- Check the static accessibility rule of 4.6(17). Note that the
11458 -- check is not enforced when within an instance body, since the
11459 -- RM requires such cases to be caught at run time.
11461 -- If the operand is a rewriting of an allocator no check is needed
11462 -- because there are no accessibility issues.
11470 then
11471 -- In an instance, this is a run-time check, but one we know
11472 -- will fail, so generate an appropriate warning. The raise
11473 -- will be generated by Expand_N_Type_Conversion.
11477 Conversion_Error_N
11479 Operand);
11482 else
11483 Conversion_Error_N
11485 Operand);
11489 -- Special accessibility checks are needed in the case of access
11490 -- discriminants declared for a limited type.
11494 then
11495 -- When the operand is a selected access discriminant the check
11496 -- needs to be made against the level of the object denoted by
11497 -- the prefix of the selected name (Object_Access_Level handles
11498 -- checking the prefix of the operand for this case).
11503 then
11504 -- In an instance, this is a run-time check, but one we know
11505 -- will fail, so generate an appropriate warning. The raise
11506 -- will be generated by Expand_N_Type_Conversion.
11510 Conversion_Error_N
11515 -- Real error if not in instance body
11517 else
11518 Conversion_Error_N
11525 -- The case of a reference to an access discriminant from
11526 -- within a limited type declaration (which will appear as
11527 -- a discriminal) is always illegal because the level of the
11528 -- discriminant is considered to be deeper than any (nameable)
11529 -- access type.
11533 and then
11536 then
11537 Conversion_Error_N
11539 Operand);
11547 -- General and anonymous access types
11550 E_Anonymous_Access_Type)
11551 and then
11552 Conversion_Check
11554 and then not
11556 E_Access_Protected_Subprogram_Type),
11558 then
11561 then
11562 Conversion_Error_N
11567 -- Check the static accessibility rule of 4.6(17). Note that the
11568 -- check is not enforced when within an instance body, since the RM
11569 -- requires such cases to be caught at run time.
11574 N_Object_Declaration
11575 then
11576 -- Ada 2012 (AI05-0149): Perform legality checking on implicit
11577 -- conversions from an anonymous access type to a named general
11578 -- access type. Such conversions are not allowed in the case of
11579 -- access parameters and stand-alone objects of an anonymous
11580 -- access type. The implicit conversion case is recognized by
11581 -- testing that Comes_From_Source is False and that it's been
11582 -- rewritten. The Comes_From_Source test isn't sufficient because
11583 -- nodes in inlined calls to predefined library routines can have
11584 -- Comes_From_Source set to False. (Is there a better way to test
11585 -- for implicit conversions???)
11592 then
11595 -- Implicit conversions aren't allowed for objects of an
11596 -- anonymous access type, since such objects have nonstatic
11597 -- levels in Ada 2012.
11600 N_Object_Declaration
11601 then
11602 Conversion_Error_N
11607 -- Implicit conversions aren't allowed for anonymous access
11608 -- parameters. The "not Is_Local_Anonymous_Access_Type" test
11609 -- is done to exclude anonymous access results.
11613 N_Function_Specification,
11614 N_Procedure_Specification)
11615 then
11616 Conversion_Error_N
11621 -- This is a case where there's an enclosing object whose
11622 -- to which the "statically deeper than" relationship does
11623 -- not apply (such as an access discriminant selected from
11624 -- a dereference of an access parameter).
11628 then
11629 Conversion_Error_N
11634 -- In other cases, the level of the operand's type must be
11635 -- statically less deep than that of the target type, else
11636 -- implicit conversion is disallowed (by RM12-8.6(27.1/3)).
11640 then
11641 Conversion_Error_N
11650 then
11651 -- In an instance, this is a run-time check, but one we know
11652 -- will fail, so generate an appropriate warning. The raise
11653 -- will be generated by Expand_N_Type_Conversion.
11657 Conversion_Error_N
11659 Operand);
11662 -- If not in an instance body, this is a real error
11664 else
11665 -- Avoid generation of spurious error message
11668 Conversion_Error_N
11670 Operand);
11676 -- Special accessibility checks are needed in the case of access
11677 -- discriminants declared for a limited type.
11681 then
11682 -- When the operand is a selected access discriminant the check
11683 -- needs to be made against the level of the object denoted by
11684 -- the prefix of the selected name (Object_Access_Level handles
11685 -- checking the prefix of the operand for this case).
11690 then
11691 -- In an instance, this is a run-time check, but one we know
11692 -- will fail, so generate an appropriate warning. The raise
11693 -- will be generated by Expand_N_Type_Conversion.
11697 Conversion_Error_N
11702 -- If not in an instance body, this is a real error
11704 else
11705 Conversion_Error_N
11712 -- The case of a reference to an access discriminant from
11713 -- within a limited type declaration (which will appear as
11714 -- a discriminal) is always illegal because the level of the
11715 -- discriminant is considered to be deeper than any (nameable)
11716 -- access type.
11719 and then
11722 then
11723 Conversion_Error_N
11725 Operand);
11731 -- In the presence of limited_with clauses we have to use non-limited
11732 -- views, if available.
11736 -- Helper function to handle limited views
11738 --------------------------
11739 -- Full_Designated_Type --
11740 --------------------------
11745 begin
11746 -- Handle the limited view of a type
11751 then
11753 else
11758 -- Local Declarations
11766 -- Start of processing for Check_Limited
11768 begin
11772 else
11774 Conversion_Error_NE
11779 -- Ada 2005 AI-384: legality rule is symmetric in both
11780 -- designated types. The conversion is legal (with possible
11781 -- constraint check) if either designated type is
11782 -- unconstrained.
11785 or else
11787 and then
11790 then
11791 -- Special case, if Value_Size has been used to make the
11792 -- sizes different, the conversion is not allowed even
11793 -- though the subtypes statically match.
11798 then
11799 Conversion_Error_NE
11802 Conversion_Error_NE
11807 -- Normal case where conversion is allowed
11809 else
11813 else
11814 Error_Msg_NE
11822 -- Access to subprogram types. If the operand is an access parameter,
11823 -- the type has a deeper accessibility that any master, and cannot be
11824 -- assigned. We must make an exception if the conversion is part of an
11825 -- assignment and the target is the return object of an extended return
11826 -- statement, because in that case the accessibility check takes place
11827 -- after the return.
11831 then
11835 and then
11839 then
11840 Conversion_Error_N
11842 Operand);
11843 Conversion_Error_N
11846 Operand);
11848 Error_Msg_NE
11853 -- Check that the designated types are subtype conformant
11859 -- Check the static accessibility rule of 4.6(20)
11863 then
11864 Conversion_Error_N
11866 Operand);
11868 -- Check that if the operand type is declared in a generic body,
11869 -- then the target type must be declared within that same body
11870 -- (enforces last sentence of 4.6(20)).
11873 declare
11879 begin
11886 Conversion_Error_N
11895 -- Remote subprogram access types
11899 then
11900 -- It is valid to convert from one RAS type to another provided
11901 -- that their specification statically match.
11903 Check_Subtype_Conformant
11906 Old_Id =>
11908 Err_Loc =>
11909 N);
11912 -- If it was legal in the generic, it's legal in the instance
11917 -- If both are tagged types, check legality of view conversions
11920 and then
11922 then
11925 -- Types derived from the same root type are convertible
11930 -- In an instance or an inlined body, there may be inconsistent views of
11931 -- the same type, or of types derived from a common root.
11934 and then
11937 then
11940 -- Special check for common access type error case
11944 then
11946 Conversion_Error_NE -- CODEFIX
11950 -- Here we have a real conversion error
11952 else
11953 Conversion_Error_NE