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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S E M _ R E S --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2014, Free Software Foundation, Inc. --
10 -- --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
20 -- --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
23 -- --
24 ------------------------------------------------------------------------------
84 -----------------------
85 -- Local Subprograms --
86 -----------------------
88 -- Second pass (top-down) type checking and overload resolution procedures
89 -- Typ is the type required by context. These procedures propagate the type
90 -- information recursively to the descendants of N. If the node is not
91 -- overloaded, its Etype is established in the first pass. If overloaded,
92 -- the Resolve routines set the correct type. For arith. operators, the
93 -- Etype is the base type of the context.
95 -- Note that Resolve_Attribute is separated off in Sem_Attr
98 -- Enforce the restrictions on the use of discriminants when constraining
99 -- a component of a discriminated type (record or concurrent type).
102 -- Given a node for an operator associated with type T, check that
103 -- the operator is visible. Operators all of whose operands are
104 -- universal must be checked for visibility during resolution
105 -- because their type is not determinable based on their operands.
107 procedure Check_Fully_Declared_Prefix
110 -- Check that the type of the prefix of a dereference is not incomplete
113 -- Given a call node, N, which is known to occur immediately within the
114 -- subprogram being called, determines whether it is a detectable case of
115 -- an infinite recursion, and if so, outputs appropriate messages. Returns
116 -- True if an infinite recursion is detected, and False otherwise.
119 -- If the type of the object being initialized uses the secondary stack
120 -- directly or indirectly, create a transient scope for the call to the
121 -- init proc. This is because we do not create transient scopes for the
122 -- initialization of individual components within the init proc itself.
123 -- Could be optimized away perhaps?
126 -- N is the node for a logical operator. If the operator is predefined, and
127 -- the root type of the operands is Standard.Boolean, then a check is made
128 -- for restriction No_Direct_Boolean_Operators. This procedure also handles
129 -- the style check for Style_Check_Boolean_And_Or.
132 -- N is either an indexed component or a selected component. This function
133 -- returns true if the prefix refers to an object that has an address
134 -- clause (the case in which we may want to issue a warning).
137 -- Determine whether E is an access type declared by an access declaration,
138 -- and not an (anonymous) allocator type.
141 -- Utility to check whether the entity for an operator is a predefined
142 -- operator, in which case the expression is left as an operator in the
143 -- tree (else it is rewritten into a call). An instance of an intrinsic
144 -- conversion operation may be given an operator name, but is not treated
145 -- like an operator. Note that an operator that is an imported back-end
146 -- builtin has convention Intrinsic, but is expected to be rewritten into
147 -- a call, so such an operator is not treated as predefined by this
148 -- predicate.
151 -- If a default expression in entry call N depends on the discriminants
152 -- of the task, it must be replaced with a reference to the discriminant
153 -- of the task being called.
155 procedure Resolve_Op_Concat_Arg
160 -- Internal procedure for Resolve_Op_Concat to resolve one operand of
161 -- concatenation operator. The operand is either of the array type or of
162 -- the component type. If the operand is an aggregate, and the component
163 -- type is composite, this is ambiguous if component type has aggregates.
166 -- Does the first part of the work of Resolve_Op_Concat
169 -- Does the "rest" of the work of Resolve_Op_Concat, after the left operand
170 -- has been resolved. See Resolve_Op_Concat for details.
208 function Operator_Kind
211 -- Utility to map the name of an operator into the corresponding Node. Used
212 -- by other node rewriting procedures.
215 -- Resolve actuals of call, and add default expressions for missing ones.
216 -- N is the Node_Id for the subprogram call, and Nam is the entity of the
217 -- called subprogram.
220 -- Called from Resolve_Call, when the prefix denotes an entry or element
221 -- of entry family. Actuals are resolved as for subprograms, and the node
222 -- is rebuilt as an entry call. Also called for protected operations. Typ
223 -- is the context type, which is used when the operation is a protected
224 -- function with no arguments, and the return value is indexed.
227 -- A call to a user-defined intrinsic operator is rewritten as a call to
228 -- the corresponding predefined operator, with suitable conversions. Note
229 -- that this applies only for intrinsic operators that denote predefined
230 -- operators, not ones that are intrinsic imports of back-end builtins.
233 -- Ditto, for arithmetic unary operators
236 -- If an operator node resolves to a call to a user-defined operator,
237 -- rewrite the node as a function call.
239 procedure Make_Call_Into_Operator
243 -- Inverse transformation: if an operator is given in functional notation,
244 -- then after resolving the node, transform into an operator node, so
245 -- that operands are resolved properly. Recall that predefined operators
246 -- do not have a full signature and special resolution rules apply.
248 procedure Rewrite_Renamed_Operator
252 -- An operator can rename another, e.g. in an instantiation. In that
253 -- case, the proper operator node must be constructed and resolved.
256 -- The String_Literal_Subtype is built for all strings that are not
257 -- operands of a static concatenation operation. If the argument is
258 -- not a N_String_Literal node, then the call has no effect.
261 -- Build subtype of array type, with the range specified by the slice
264 -- Called after N has been resolved and evaluated, but before range checks
265 -- have been applied. Currently simplifies a combination of floating-point
266 -- to integer conversion and Rounding or Truncation attribute.
269 -- A universal_fixed expression in an universal context is unambiguous if
270 -- there is only one applicable fixed point type. Determining whether there
271 -- is only one requires a search over all visible entities, and happens
272 -- only in very pathological cases (see 6115-006).
274 -------------------------
275 -- Ambiguous_Character --
276 -------------------------
281 begin
285 -- First the ones in Standard
290 -- Include Wide_Wide_Character in Ada 2005 mode
296 -- Now any other types that match
306 -------------------------
307 -- Analyze_And_Resolve --
308 -------------------------
311 begin
317 begin
322 -- Versions with check(s) suppressed
324 procedure Analyze_And_Resolve
328 is
331 begin
333 declare
335 begin
341 else
342 declare
344 begin
352 and then Scope_Is_Transient
353 then
354 -- This can only happen if a transient scope was created for an inner
355 -- expression, which will be removed upon completion of the analysis
356 -- of an enclosing construct. The transient scope must have the
357 -- suppress status of the enclosing environment, not of this Analyze
358 -- call.
361 Scope_Suppress;
365 procedure Analyze_And_Resolve
368 is
371 begin
373 declare
375 begin
381 else
382 declare
384 begin
393 Scope_Suppress;
397 ----------------------------
398 -- Check_Discriminant_Use --
399 ----------------------------
407 begin
408 -- Any use in a spec-expression is legal
415 -- Discriminant cannot be used to constrain a scalar type
422 then
427 -- The following check catches the unusual case where a
428 -- discriminant appears within an index constraint that is part of
429 -- a larger expression within a constraint on a component, e.g. "C
430 -- : Int range 1 .. F (new A(1 .. D))". For now we only check case
431 -- of record components, and note that a similar check should also
432 -- apply in the case of discriminant constraints below. ???
434 -- Note that the check for N_Subtype_Declaration below is to
435 -- detect the valid use of discriminants in the constraints of a
436 -- subtype declaration when this subtype declaration appears
437 -- inside the scope of a record type (which is syntactically
438 -- illegal, but which may be created as part of derived type
439 -- processing for records). See Sem_Ch3.Build_Derived_Record_Type
440 -- for more info.
444 and then not
446 and then
448 N_Subtype_Declaration)
450 then
451 Error_Msg_N
456 -- Detect a common error:
458 -- type R (D : Positive := 100) is record
459 -- Name : String (1 .. D);
460 -- end record;
462 -- The default value causes an object of type R to be allocated
463 -- with room for Positive'Last characters. The RM does not mandate
464 -- the allocation of the maximum size, but that is what GNAT does
465 -- so we should warn the programmer that there is a problem.
474 -- Return True if type T has a large enough range that any
475 -- array whose index type covered the whole range of the type
476 -- would likely raise Storage_Error.
478 ------------------------
479 -- Large_Storage_Type --
480 ------------------------
483 begin
484 -- The type is considered large if its bounds are known at
485 -- compile time and if it requires at least as many bits as
486 -- a Positive to store the possible values.
490 and then
495 -- Start of processing for Check_Large
497 begin
498 -- Check that the Disc has a large range
504 -- If the enclosing type is limited, we allocate only the
505 -- default value, not the maximum, and there is no need for
506 -- a warning.
512 -- Check that it is the high bound
516 then
520 -- Check the array allows a large range at this bound. First
521 -- find the array
535 -- Next, find the dimension
543 loop
552 -- Now, check the dimension has a large range
558 -- Warn about the danger
560 Error_Msg_N
570 -- Legal case is in index or discriminant constraint
573 N_Discriminant_Association)
574 then
576 Error_Msg_N
581 then
582 Error_Msg_N
588 -- Otherwise, context is an expression. It should not be within (i.e. a
589 -- subexpression of) a constraint for a component.
591 else
595 N_Subtype_Indication,
596 N_Entry_Declaration)
597 loop
603 -- If the discriminant is used in an expression that is a bound of a
604 -- scalar type, an Itype is created and the bounds are attached to
605 -- its range, not to the original subtype indication. Such use is of
606 -- course a double fault.
610 N_Derived_Type_Definition)
613 -- The constraint itself may be given by a subtype indication,
614 -- rather than by a more common discrete range.
617 and then
621 then
622 Error_Msg_N
628 --------------------------------
629 -- Check_For_Visible_Operator --
630 --------------------------------
633 begin
635 Error_Msg_NE -- CODEFIX
637 Error_Msg_N -- CODEFIX
642 ----------------------------------
643 -- Check_Fully_Declared_Prefix --
644 ----------------------------------
646 procedure Check_Fully_Declared_Prefix
649 is
650 begin
651 -- Check that the designated type of the prefix of a dereference is
652 -- not an incomplete type. This cannot be done unconditionally, because
653 -- dereferences of private types are legal in default expressions. This
654 -- case is taken care of in Check_Fully_Declared, called below. There
655 -- are also 2005 cases where it is legal for the prefix to be unfrozen.
657 -- This consideration also applies to similar checks for allocators,
658 -- qualified expressions, and type conversions.
660 -- An additional exception concerns other per-object expressions that
661 -- are not directly related to component declarations, in particular
662 -- representation pragmas for tasks. These will be per-object
663 -- expressions if they depend on discriminants or some global entity.
664 -- If the task has access discriminants, the designated type may be
665 -- incomplete at the point the expression is resolved. This resolution
666 -- takes place within the body of the initialization procedure, where
667 -- the discriminant is replaced by its discriminal.
671 then
674 -- Ada 2005 (AI-326): Tagged incomplete types allowed. The wrong usages
675 -- are handled by Analyze_Access_Attribute, Analyze_Assignment,
676 -- Analyze_Object_Renaming, and Freeze_Entity.
682 E_Incomplete_Type
684 then
686 else
691 ------------------------------
692 -- Check_Infinite_Recursion --
693 ------------------------------
700 -- Check whether list of actuals is identical to list of formals of
701 -- called function (which is also the enclosing scope).
703 ------------------------
704 -- Same_Argument_List --
705 ------------------------
712 begin
715 else
724 then
735 -- Start of processing for Check_Infinite_Recursion
737 begin
738 -- Special case, if this is a procedure call and is a call to the
739 -- current procedure with the same argument list, then this is for
740 -- sure an infinite recursion and we insert a call to raise SE.
744 and then Same_Argument_List
745 then
746 declare
748 begin
752 then
764 -- If not that special case, search up tree, quitting if we reach a
765 -- construct (e.g. a conditional) that tells us that this is not a
766 -- case for an infinite recursion warning.
769 loop
772 -- If no parent, then we were not inside a subprogram, this can for
773 -- example happen when processing certain pragmas in a spec. Just
774 -- return False in this case.
780 -- Done if we get to subprogram body, this is definitely an infinite
781 -- recursion case if we did not find anything to stop us.
785 -- If appearing in conditional, result is false
788 N_And_Then,
789 N_Case_Expression,
790 N_Case_Statement,
791 N_If_Expression,
792 N_If_Statement)
793 then
798 then
799 -- If the call is the expression of a return statement and the
800 -- actuals are identical to the formals, it's worth a warning.
801 -- However, we skip this if there is an immediately preceding
802 -- raise statement, since the call is never executed.
804 -- Furthermore, this corresponds to a common idiom:
806 -- function F (L : Thing) return Boolean is
807 -- begin
808 -- raise Program_Error;
809 -- return F (L);
810 -- end F;
812 -- for generating a stub function
815 and then Same_Argument_List
816 then
819 -- OK, return statement is in a statement list, look for raise
821 declare
824 begin
825 -- Skip past N_Freeze_Entity nodes generated by expansion
830 loop
834 -- If no raise statement, give warning. We look at the
835 -- original node, because in the case of "raise ... with
836 -- ...", the node has been transformed into a call.
839 and then
847 else
859 -------------------------------
860 -- Check_Initialization_Call --
861 -------------------------------
867 -- Check whether the creation of an object of the type will involve
868 -- use of the secondary stack. If T is a record type, this is true
869 -- if the expression for some component uses the secondary stack, e.g.
870 -- through a call to a function that returns an unconstrained value.
871 -- False if T is controlled, because cleanups occur elsewhere.
873 -------------
874 -- Uses_SS --
875 -------------
882 begin
883 -- Normally we want to use the underlying type, but if it's not set
884 -- then continue with T.
901 then
902 -- The expression for a dynamic component may be rewritten
903 -- as a dereference, so retrieve original node.
907 -- Return True if the expression is a call to a function
908 -- (including an attribute function such as Image, or a
909 -- user-defined operator) with a result that requires a
910 -- transient scope.
917 then
930 else
935 -- Start of processing for Check_Initialization_Call
937 begin
938 -- Establish a transient scope if the type needs it
945 ---------------------------------------
946 -- Check_No_Direct_Boolean_Operators --
947 ---------------------------------------
950 begin
953 then
954 -- Restriction only applies to original source code
961 -- Do style check (but skip if in instance, error is on template)
970 ------------------------------
971 -- Check_Parameterless_Call --
972 ------------------------------
978 -- If the prefix is of an access_to_subprogram type, the node must be
979 -- rewritten as a call. Ditto if the prefix is overloaded and all its
980 -- interpretations are access to subprograms.
982 ---------------------------
983 -- Prefix_Is_Access_Subp --
984 ---------------------------
990 begin
991 -- If the context is an attribute reference that can apply to
992 -- functions, this is never a parameterless call (RM 4.1.4(6)).
996 Name_Code_Address,
997 Name_Access)
998 then
1003 return
1006 else
1011 then
1022 -- Start of processing for Check_Parameterless_Call
1024 begin
1025 -- Defend against junk stuff if errors already detected
1032 then
1039 -- If the context expects a value, and the name is a procedure, this is
1040 -- most likely a missing 'Access. Don't try to resolve the parameterless
1041 -- call, error will be caught when the outer call is analyzed.
1046 and then
1048 N_Function_Call,
1049 N_Procedure_Call_Statement)
1050 then
1054 -- Rewrite as call if overloadable entity that is (or could be, in the
1055 -- overloaded case) a function call. If we know for sure that the entity
1056 -- is an enumeration literal, we do not rewrite it.
1058 -- If the entity is the name of an operator, it cannot be a call because
1059 -- operators cannot have default parameters. In this case, this must be
1060 -- a string whose contents coincide with an operator name. Set the kind
1061 -- of the node appropriately.
1069 -- Rewrite as call if it is an explicit dereference of an expression of
1070 -- a subprogram access type, and the subprogram type is not that of a
1071 -- procedure or entry.
1073 or else
1076 -- Rewrite as call if it is a selected component which is a function,
1077 -- this is the case of a call to a protected function (which may be
1078 -- overloaded with other protected operations).
1080 or else
1083 or else
1085 E_Procedure)
1088 -- If one of the above three conditions is met, rewrite as call. Apply
1089 -- the rewriting only once.
1091 then
1094 then
1096 -- This may be a prefixed call that was not fully analyzed, e.g.
1097 -- an actual in an instance.
1102 then
1110 -- The node is the name of the parameterless call. Preserve its
1111 -- descendants, which may be complex expressions.
1115 -- If overloaded, overload set belongs to new copy
1119 -- Change node to parameterless function call (note that the
1120 -- Parameter_Associations associations field is left set to Empty,
1121 -- its normal default value since there are no parameters)
1139 --------------------------------
1140 -- Is_Atomic_Ref_With_Address --
1141 --------------------------------
1146 begin
1150 else
1151 declare
1154 begin
1162 -----------------------------
1163 -- Is_Definite_Access_Type --
1164 -----------------------------
1168 begin
1174 ----------------------
1175 -- Is_Predefined_Op --
1176 ----------------------
1179 begin
1180 -- Predefined operators are intrinsic subprograms
1186 -- A call to a back-end builtin is never a predefined operator
1197 -----------------------------
1198 -- Make_Call_Into_Operator --
1199 -----------------------------
1201 procedure Make_Call_Into_Operator
1205 is
1220 -- If the operand is not universal, and the operator is given by an
1221 -- expanded name, verify that the operand has an interpretation with a
1222 -- type defined in the given scope of the operator.
1225 -- Find a type of the given class in package Pack that contains the
1226 -- operator.
1228 ---------------------------
1229 -- Operand_Type_In_Scope --
1230 ---------------------------
1237 begin
1241 else
1255 ---------------
1256 -- Type_In_P --
1257 ---------------
1263 -- Verify that node is not part of the type declaration for the
1264 -- candidate type, which would otherwise be invisible.
1266 -------------
1267 -- In_Decl --
1268 -------------
1274 begin
1283 else
1286 loop
1289 else
1298 -- Start of processing for Type_In_P
1300 begin
1301 -- If the context type is declared in the prefix package, this is the
1302 -- desired base type.
1307 else
1311 and then not In_Decl
1312 then
1323 -- Start of processing for Make_Call_Into_Operator
1325 begin
1328 -- Binary operator
1338 -- Unary operator
1340 else
1346 -- If the operator is denoted by an expanded name, and the prefix is
1347 -- not Standard, but the operator is a predefined one whose scope is
1348 -- Standard, then this is an implicit_operator, inserted as an
1349 -- interpretation by the procedure of the same name. This procedure
1350 -- overestimates the presence of implicit operators, because it does
1351 -- not examine the type of the operands. Verify now that the operand
1352 -- type appears in the given scope. If right operand is universal,
1353 -- check the other operand. In the case of concatenation, either
1354 -- argument can be the component type, so check the type of the result.
1355 -- If both arguments are literals, look for a type of the right kind
1356 -- defined in the given scope. This elaborate nonsense is brought to
1357 -- you courtesy of b33302a. The type itself must be frozen, so we must
1358 -- find the type of the proper class in the given scope.
1360 -- A final wrinkle is the multiplication operator for fixed point types,
1361 -- which is defined in Standard only, and not in the scope of the
1362 -- fixed point type itself.
1367 -- If this is a package renaming, get renamed entity, which will be
1368 -- the scope of the operands if operaton is type-correct.
1374 -- If the entity being called is defined in the given package, it is
1375 -- a renaming of a predefined operator, and known to be legal.
1379 then
1382 -- Visibility does not need to be checked in an instance: if the
1383 -- operator was not visible in the generic it has been diagnosed
1384 -- already, else there is an implicit copy of it in the instance.
1392 then
1397 -- Ada 2005 AI-420: Predefined equality on Universal_Access is
1398 -- available.
1403 then
1406 else
1415 and then Is_Binary
1417 then
1423 -- Verify that the scope contains a type that corresponds to
1424 -- the given literal. Optimize the case where Pack is Standard.
1446 else
1455 else
1464 then
1467 -- If the type is defined elsewhere, and the operator is not
1468 -- defined in the given scope (by a renaming declaration, e.g.)
1469 -- then this is an error as well. If an extension of System is
1470 -- present, and the type may be defined there, Pack must be
1471 -- System itself.
1478 then
1481 else
1487 then
1494 Error_Msg_NE
1499 -- Detect a mismatch between the context type and the result type
1500 -- in the named package, which is otherwise not detected if the
1501 -- operands are universal. Check is only needed if source entity is
1502 -- an operator, not a function that renames an operator.
1509 and then not In_Instance
1510 then
1513 then
1514 -- Already checked above
1518 -- Operator may be defined in an extension of System
1522 then
1525 else
1526 -- Could we use Wrong_Type here??? (this would require setting
1527 -- Etype (N) to the actual type found where Typ was expected).
1538 else
1542 -- If this is a call to a function that renames a predefined equality,
1543 -- the renaming declaration provides a type that must be used to
1544 -- resolve the operands. This must be done now because resolution of
1545 -- the equality node will not resolve any remaining ambiguity, and it
1546 -- assumes that the first operand is not overloaded.
1551 then
1559 -- Do rewrite setting Comes_From_Source on the result if the original
1560 -- call came from source. Although it is not strictly the case that the
1561 -- operator as such comes from the source, logically it corresponds
1562 -- exactly to the function call in the source, so it should be marked
1563 -- this way (e.g. to make sure that validity checks work fine).
1565 declare
1567 begin
1572 -- If this is an arithmetic operator and the result type is private,
1573 -- the operands and the result must be wrapped in conversion to
1574 -- expose the underlying numeric type and expand the proper checks,
1575 -- e.g. on division.
1579 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
1580 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
1589 else
1593 -- If in ASIS_Mode, propagate operand types to original actuals of
1594 -- function call, which would otherwise not be fully resolved. If
1595 -- the call has already been constant-folded, nothing to do. We
1596 -- relocate the operand nodes rather than copy them, to preserve
1597 -- original_node pointers, given that the operands themselves may
1598 -- have been rewritten. If the call was itself a rewriting of an
1599 -- operator node, nothing to do.
1601 if ASIS_Mode
1604 then
1610 else
1619 -------------------
1620 -- Operator_Kind --
1621 -------------------
1623 function Operator_Kind
1626 is
1629 begin
1630 -- Use CASE statement or array???
1667 else
1671 -- Unary operators
1673 else
1682 else
1690 ----------------------------
1691 -- Preanalyze_And_Resolve --
1692 ----------------------------
1697 begin
1701 -- Normally, we suppress all checks for this preanalysis. There is no
1702 -- point in processing them now, since they will be applied properly
1703 -- and in the proper location when the default expressions reanalyzed
1704 -- and reexpanded later on. We will also have more information at that
1705 -- point for possible suppression of individual checks.
1707 -- However, in SPARK mode, most expansion is suppressed, and this
1708 -- later reanalysis and reexpansion may not occur. SPARK mode does
1709 -- require the setting of checking flags for proof purposes, so we
1710 -- do the SPARK preanalysis without suppressing checks.
1712 -- This special handling for SPARK mode is required for example in the
1713 -- case of Ada 2012 constructs such as quantified expressions, which are
1714 -- expanded in two separate steps.
1718 else
1722 Expander_Mode_Restore;
1726 -- Version without context type
1731 begin
1738 Expander_Mode_Restore;
1742 ----------------------------------
1743 -- Replace_Actual_Discriminants --
1744 ----------------------------------
1751 -- Comment needed???
1753 -------------------
1754 -- Process_Discr --
1755 -------------------
1760 begin
1766 then
1782 -- Start of processing for Replace_Actual_Discriminants
1784 begin
1798 else
1803 -------------
1804 -- Resolve --
1805 -------------
1821 -- Determine whether a node comes from a predefined library unit or
1822 -- Standard.
1825 -- Try and fix up a literal so that it matches its expected type. New
1826 -- literals are manufactured if necessary to avoid cascaded errors.
1829 -- Additional diagnostics when an ambiguous call has an ambiguous
1830 -- argument (typically a controlling actual).
1833 -- Called when attempt at resolving current expression fails
1835 ------------------------------------
1836 -- Comes_From_Predefined_Lib_Unit --
1837 -------------------------------------
1840 begin
1841 return
1843 or else Is_Predefined_File_Name
1847 --------------------
1848 -- Patch_Up_Value --
1849 --------------------
1852 begin
1869 then
1874 Char_Literal_Value =>
1890 -------------------------------
1891 -- Report_Ambiguous_Argument --
1892 -------------------------------
1899 begin
1903 then
1906 -- Could use comments on what is going on here???
1914 else
1923 -----------------------
1924 -- Resolution_Failed --
1925 -----------------------
1928 begin
1934 -- The caller will return without calling the expander, so we need
1935 -- to set the analyzed flag. Note that it is fine to set Analyzed
1936 -- to True even if we are in the middle of a shallow analysis,
1937 -- (see the spec of sem for more details) since this is an error
1938 -- situation anyway, and there is no point in repeating the
1939 -- analysis later (indeed it won't work to repeat it later, since
1940 -- we haven't got a clear resolution of which entity is being
1941 -- referenced.)
1947 -- Start of processing for Resolve
1949 begin
1954 -- Access attribute on remote subprogram cannot be used for a non-remote
1955 -- access-to-subprogram type.
1959 Name_Unrestricted_Access,
1960 Name_Unchecked_Access)
1966 then
1967 Error_Msg_N
1973 -- If the context is a Remote_Access_To_Subprogram, access attributes
1974 -- must be resolved with the corresponding fat pointer. There is no need
1975 -- to check for the attribute name since the return type of an
1976 -- attribute is never a remote type.
1981 then
1982 declare
1990 begin
1991 -- Check that Typ is a remote access-to-subprogram type
1995 -- Prefix (N) must statically denote a remote subprogram
1996 -- declared in a package specification.
2000 Attr = Attribute_Unrestricted_Access
2001 then
2016 or else
2018 then
2020 Error_Msg_N
2022 N);
2025 -- If we are generating code in distributed mode, perform
2026 -- semantic checks against corresponding remote entities.
2028 if Expander_Active
2030 then
2031 Check_Subtype_Conformant
2033 Old_Id => Designated_Type
2059 then
2064 -- Return if already analyzed
2071 -- Any case of Any_Type as the Etype value means that we had a
2072 -- previous error.
2081 -- The resolution of an Expression_With_Actions is determined by
2082 -- its Expression.
2090 -- If not overloaded, then we know the type, and all that needs doing
2091 -- is to check that this type is compatible with the context.
2097 -- In the overloaded case, we must select the interpretation that
2098 -- is compatible with the context (i.e. the type passed to Resolve)
2100 else
2101 -- Loop through possible interpretations
2111 -- We are only interested in interpretations that are compatible
2112 -- with the expected type, any other interpretations are ignored.
2117 Write_Eol;
2120 else
2121 -- Skip the current interpretation if it is disabled by an
2122 -- abstract operator. This action is performed only when the
2123 -- type against which we are resolving is the same as the
2124 -- type of the interpretation.
2131 then
2139 -- First matching interpretation
2147 -- Matching interpretation that is not the first, maybe an
2148 -- error, but there are some cases where preference rules are
2149 -- used to choose between the two possibilities. These and
2150 -- some more obscure cases are handled in Disambiguate.
2152 else
2153 -- If the current statement is part of a predefined library
2154 -- unit, then all interpretations which come from user level
2155 -- packages should not be considered. Check previous and
2156 -- current one.
2164 -- Previous interpretation must be discarded
2174 -- Otherwise apply further disambiguation steps
2179 -- Disambiguation has succeeded. Skip the remaining
2180 -- interpretations.
2190 else
2191 -- Before we issue an ambiguity complaint, check for
2192 -- the case of a subprogram call where at least one
2193 -- of the arguments is Any_Type, and if so, suppress
2194 -- the message, since it is a cascaded error.
2197 declare
2201 begin
2213 Write_Eol;
2226 then
2231 then
2235 -- Not that special case, so issue message using the
2236 -- flag Ambiguous to control printing of the header
2237 -- message only at the start of an ambiguous set.
2242 then
2243 Error_Msg_N
2246 else
2247 Error_Msg_NE -- CODEFIX
2255 Error_Msg_N
2257 else
2258 Error_Msg_N -- CODEFIX
2264 then
2265 Report_Ambiguous_Argument;
2271 -- By default, the error message refers to the candidate
2272 -- interpretation. But if it is a predefined operator, it
2273 -- is implicitly declared at the declaration of the type
2274 -- of the operand. Recover the sloc of that declaration
2275 -- for the error message.
2281 Standard_Standard
2282 then
2287 then
2295 Standard_Standard
2296 then
2301 then
2305 -- If this is an indirect call, use the subprogram_type
2306 -- in the message, to have a meaningful location. Also
2307 -- indicate if this is an inherited operation, created
2308 -- by a type declaration.
2313 then
2315 Error_Msg_Sloc :=
2317 else
2324 then
2325 -- Special-case the message for universal_fixed
2326 -- operators, which are not declared with the type
2327 -- of the operand, but appear forever in Standard.
2331 then
2332 Error_Msg_N
2335 else
2336 Error_Msg_N
2340 elsif
2342 then
2343 Error_Msg_N
2345 else
2346 Error_Msg_N -- CODEFIX
2353 -- We have a matching interpretation, Expr_Type is the type
2354 -- from this interpretation, and Seen is the entity.
2356 -- For an operator, just set the entity name. The type will be
2357 -- set by the specific operator resolution routine.
2372 -- AI05-0139-2: Expression is overloaded because type has
2373 -- implicit dereference. If type matches context, no implicit
2374 -- dereference is involved.
2385 then
2386 -- If the node is a general indexing, the dereference is
2387 -- is inserted when resolving the rewritten form, else
2388 -- insert it now.
2392 then
2396 -- For an explicit dereference, attribute reference, range,
2397 -- short-circuit form (which is not an operator node), or call
2398 -- with a name that is an explicit dereference, there is
2399 -- nothing to be done at this point.
2402 N_Attribute_Reference,
2403 N_And_Then,
2404 N_Indexed_Component,
2405 N_Or_Else,
2406 N_Range,
2407 N_Selected_Component,
2408 N_Slice)
2410 then
2413 -- For procedure or function calls, set the type of the name,
2414 -- and also the entity pointer for the prefix.
2418 then
2425 then
2430 -- For all other cases, just set the type of the Name
2432 else
2440 -- Move to next interpretation
2448 -- At this stage Found indicates whether or not an acceptable
2449 -- interpretation exists. If not, then we have an error, except that if
2450 -- the context is Any_Type as a result of some other error, then we
2451 -- suppress the error report.
2456 -- If type we are looking for is Void, then this is the procedure
2457 -- call case, and the error is simply that what we gave is not a
2458 -- procedure name (we think of procedure calls as expressions with
2459 -- types internally, but the user doesn't think of them this way).
2463 -- Special case message if function used as a procedure
2468 then
2469 Error_Msg_NE
2473 -- Otherwise give general message (not clear what cases this
2474 -- covers, but no harm in providing for them).
2476 else
2482 -- Otherwise we do have a subexpression with the wrong type
2484 -- Check for the case of an allocator which uses an access type
2485 -- instead of the designated type. This is a common error and we
2486 -- specialize the message, posting an error on the operand of the
2487 -- allocator, complaining that we expected the designated type of
2488 -- the allocator.
2494 then
2498 -- Check for view mismatch on Null in instances, for which the
2499 -- view-swapping mechanism has no identifier.
2505 then
2510 -- Check for an aggregate. Sometimes we can get bogus aggregates
2511 -- from misuse of parentheses, and we are about to complain about
2512 -- the aggregate without even looking inside it.
2514 -- Instead, if we have an aggregate of type Any_Composite, then
2515 -- analyze and resolve the component fields, and then only issue
2516 -- another message if we get no errors doing this (otherwise
2517 -- assume that the errors in the aggregate caused the problem).
2521 then
2522 -- Disable expansion in any case. If there is a type mismatch
2523 -- it may be fatal to try to expand the aggregate. The flag
2524 -- would otherwise be set to false when the error is posted.
2528 declare
2530 -- Check one aggregate, and set Found to True if we have a
2531 -- definite error in any of its elements
2534 -- Check one element of aggregate and set Found to True if
2535 -- we definitely have an error in the element.
2537 ----------------
2538 -- Check_Aggr --
2539 ----------------
2544 begin
2557 -- If this is a default-initialized component, then
2558 -- there is nothing to check. The box will be
2559 -- replaced by the appropriate call during late
2560 -- expansion.
2571 ----------------
2572 -- Check_Elmt --
2573 ----------------
2576 begin
2577 -- If we have a nested aggregate, go inside it (to
2578 -- attempt a naked analyze-resolve of the aggregate can
2579 -- cause undesirable cascaded errors). Do not resolve
2580 -- expression if it needs a type from context, as for
2581 -- integer * fixed expression.
2586 else
2591 then
2601 begin
2606 -- Looks like we have a type error, but check for special case
2607 -- of Address wanted, integer found, with the configuration pragma
2608 -- Allow_Integer_Address active. If we have this case, introduce
2609 -- an unchecked conversion to allow the integer expression to be
2610 -- treated as an Address. The reverse case of integer wanted,
2611 -- Address found, is treated in an analogous manner.
2619 -- That special Allow_Integer_Address check did not appply, so we
2620 -- have a real type error. If an error message was issued already,
2621 -- Found got reset to True, so if it's still False, issue standard
2622 -- Wrong_Type message.
2626 declare
2629 begin
2635 -- Protected operation: retrieve operation name
2639 else
2644 Error_Msg_NE
2650 declare
2654 begin
2661 Error_Msg_NE
2667 else
2671 else
2677 Resolution_Failed;
2680 -- Test if we have more than one interpretation for the context
2683 Resolution_Failed;
2686 -- Only one intepretation
2688 else
2689 -- In Ada 2005, if we have something like "X : T := 2 + 2;", where
2690 -- the "+" on T is abstract, and the operands are of universal type,
2691 -- the above code will have (incorrectly) resolved the "+" to the
2692 -- universal one in Standard. Therefore check for this case and give
2693 -- an error. We can't do this earlier, because it would cause legal
2694 -- cases to get errors (when some other type has an abstract "+").
2700 then
2705 then
2706 Error_Msg_NE
2715 -- Here we have an acceptable interpretation for the context
2717 -- Propagate type information and normalize tree for various
2718 -- predefined operations. If the context only imposes a class of
2719 -- types, rather than a specific type, propagate the actual type
2720 -- downward.
2726 Typ = Any_Discrete
2727 then
2730 -- Any_Fixed is legal in a real context only if a specific fixed-
2731 -- point type is imposed. If Norman Cohen can be confused by this,
2732 -- it deserves a separate message.
2736 then
2743 -- A user-defined operator is transformed into a function call at
2744 -- this point, so that further processing knows that operators are
2745 -- really operators (i.e. are predefined operators). User-defined
2746 -- operators that are intrinsic are just renamings of the predefined
2747 -- ones, and need not be turned into calls either, but if they rename
2748 -- a different operator, we must transform the node accordingly.
2749 -- Instantiations of Unchecked_Conversion are intrinsic but are
2750 -- treated as functions, even if given an operator designator.
2755 then
2761 and then
2763 N_Subprogram_Renaming_Declaration
2764 then
2767 -- If the node is rewritten, it will be fully resolved in
2768 -- Rewrite_Renamed_Operator.
2778 when N_Aggregate => Resolve_Aggregate (N, Ctx_Type);
2780 when N_Allocator => Resolve_Allocator (N, Ctx_Type);
2782 when N_Short_Circuit
2783 => Resolve_Short_Circuit (N, Ctx_Type);
2785 when N_Attribute_Reference
2786 => Resolve_Attribute (N, Ctx_Type);
2788 when N_Case_Expression
2789 => Resolve_Case_Expression (N, Ctx_Type);
2791 when N_Character_Literal
2792 => Resolve_Character_Literal (N, Ctx_Type);
2794 when N_Expanded_Name
2795 => Resolve_Entity_Name (N, Ctx_Type);
2797 when N_Explicit_Dereference
2798 => Resolve_Explicit_Dereference (N, Ctx_Type);
2800 when N_Expression_With_Actions
2801 => Resolve_Expression_With_Actions (N, Ctx_Type);
2803 when N_Extension_Aggregate
2804 => Resolve_Extension_Aggregate (N, Ctx_Type);
2806 when N_Function_Call
2807 => Resolve_Call (N, Ctx_Type);
2809 when N_Identifier
2810 => Resolve_Entity_Name (N, Ctx_Type);
2812 when N_If_Expression
2813 => Resolve_If_Expression (N, Ctx_Type);
2815 when N_Indexed_Component
2816 => Resolve_Indexed_Component (N, Ctx_Type);
2818 when N_Integer_Literal
2819 => Resolve_Integer_Literal (N, Ctx_Type);
2821 when N_Membership_Test
2822 => Resolve_Membership_Op (N, Ctx_Type);
2824 when N_Null => Resolve_Null (N, Ctx_Type);
2826 when N_Op_And | N_Op_Or | N_Op_Xor
2827 => Resolve_Logical_Op (N, Ctx_Type);
2829 when N_Op_Eq | N_Op_Ne
2830 => Resolve_Equality_Op (N, Ctx_Type);
2832 when N_Op_Lt | N_Op_Le | N_Op_Gt | N_Op_Ge
2833 => Resolve_Comparison_Op (N, Ctx_Type);
2835 when N_Op_Not => Resolve_Op_Not (N, Ctx_Type);
2837 when N_Op_Add | N_Op_Subtract | N_Op_Multiply |
2838 N_Op_Divide | N_Op_Mod | N_Op_Rem
2840 => Resolve_Arithmetic_Op (N, Ctx_Type);
2842 when N_Op_Concat => Resolve_Op_Concat (N, Ctx_Type);
2844 when N_Op_Expon => Resolve_Op_Expon (N, Ctx_Type);
2846 when N_Op_Plus | N_Op_Minus | N_Op_Abs
2847 => Resolve_Unary_Op (N, Ctx_Type);
2849 when N_Op_Shift => Resolve_Shift (N, Ctx_Type);
2851 when N_Procedure_Call_Statement
2852 => Resolve_Call (N, Ctx_Type);
2854 when N_Operator_Symbol
2855 => Resolve_Operator_Symbol (N, Ctx_Type);
2857 when N_Qualified_Expression
2858 => Resolve_Qualified_Expression (N, Ctx_Type);
2860 -- Why is the following null, needs a comment ???
2862 when N_Quantified_Expression
2863 => null;
2865 when N_Raise_Expression
2866 => Resolve_Raise_Expression (N, Ctx_Type);
2868 when N_Raise_xxx_Error
2869 => Set_Etype (N, Ctx_Type);
2871 when N_Range => Resolve_Range (N, Ctx_Type);
2873 when N_Real_Literal
2874 => Resolve_Real_Literal (N, Ctx_Type);
2876 when N_Reference => Resolve_Reference (N, Ctx_Type);
2878 when N_Selected_Component
2879 => Resolve_Selected_Component (N, Ctx_Type);
2881 when N_Slice => Resolve_Slice (N, Ctx_Type);
2883 when N_String_Literal
2884 => Resolve_String_Literal (N, Ctx_Type);
2886 when N_Type_Conversion
2887 => Resolve_Type_Conversion (N, Ctx_Type);
2889 when N_Unchecked_Expression =>
2890 Resolve_Unchecked_Expression (N, Ctx_Type);
2892 when N_Unchecked_Type_Conversion =>
2893 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
2894 end case;
2896 -- Ada 2012 (AI05-0149): Apply an (implicit) conversion to an
2897 -- expression of an anonymous access type that occurs in the context
2898 -- of a named general access type, except when the expression is that
2899 -- of a membership test. This ensures proper legality checking in
2900 -- terms of allowed conversions (expressions that would be illegal to
2901 -- convert implicitly are allowed in membership tests).
2903 if Ada_Version >= Ada_2012
2904 and then Ekind (Ctx_Type) = E_General_Access_Type
2905 and then Ekind (Etype (N)) = E_Anonymous_Access_Type
2906 and then Nkind (Parent (N)) not in N_Membership_Test
2907 then
2908 Rewrite (N, Convert_To (Ctx_Type, Relocate_Node (N)));
2909 Analyze_And_Resolve (N, Ctx_Type);
2910 end if;
2912 -- If the subexpression was replaced by a non-subexpression, then
2913 -- all we do is to expand it. The only legitimate case we know of
2914 -- is converting procedure call statement to entry call statements,
2915 -- but there may be others, so we are making this test general.
2917 if Nkind (N) not in N_Subexpr then
2918 Debug_A_Exit ("resolving ", N, " (done)");
2919 Expand (N);
2920 return;
2921 end if;
2923 -- The expression is definitely NOT overloaded at this point, so
2924 -- we reset the Is_Overloaded flag to avoid any confusion when
2925 -- reanalyzing the node.
2927 Set_Is_Overloaded (N, False);
2929 -- Freeze expression type, entity if it is a name, and designated
2930 -- type if it is an allocator (RM 13.14(10,11,13)).
2932 -- Now that the resolution of the type of the node is complete, and
2933 -- we did not detect an error, we can expand this node. We skip the
2934 -- expand call if we are in a default expression, see section
2935 -- "Handling of Default Expressions" in Sem spec.
2937 Debug_A_Exit ("resolving ", N, " (done)");
2939 -- We unconditionally freeze the expression, even if we are in
2940 -- default expression mode (the Freeze_Expression routine tests this
2941 -- flag and only freezes static types if it is set).
2943 -- Ada 2012 (AI05-177): The declaration of an expression function
2944 -- does not cause freezing, but we never reach here in that case.
2945 -- Here we are resolving the corresponding expanded body, so we do
2946 -- need to perform normal freezing.
2948 Freeze_Expression (N);
2950 -- Now we can do the expansion
2952 Expand (N);
2953 end if;
2954 end Resolve;
2956 -------------
2957 -- Resolve --
2958 -------------
2960 -- Version with check(s) suppressed
2962 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
2963 begin
2964 if Suppress = All_Checks then
2965 declare
2966 Sva : constant Suppress_Array := Scope_Suppress.Suppress;
2967 begin
2968 Scope_Suppress.Suppress := (others => True);
2969 Resolve (N, Typ);
2970 Scope_Suppress.Suppress := Sva;
2971 end;
2973 else
2974 declare
2975 Svg : constant Boolean := Scope_Suppress.Suppress (Suppress);
2976 begin
2977 Scope_Suppress.Suppress (Suppress) := True;
2978 Resolve (N, Typ);
2979 Scope_Suppress.Suppress (Suppress) := Svg;
2980 end;
2981 end if;
2982 end Resolve;
2984 -------------
2985 -- Resolve --
2986 -------------
2988 -- Version with implicit type
2990 procedure Resolve (N : Node_Id) is
2991 begin
2992 Resolve (N, Etype (N));
2993 end Resolve;
2995 ---------------------
2996 -- Resolve_Actuals --
2997 ---------------------
2999 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
3000 Loc : constant Source_Ptr := Sloc (N);
3001 A : Node_Id;
3002 A_Id : Entity_Id;
3003 A_Typ : Entity_Id;
3004 F : Entity_Id;
3005 F_Typ : Entity_Id;
3006 Prev : Node_Id := Empty;
3007 Orig_A : Node_Id;
3009 procedure Check_Aliased_Parameter;
3010 -- Check rules on aliased parameters and related accessibility rules
3011 -- in (RM 3.10.2 (10.2-10.4)).
3013 procedure Check_Argument_Order;
3014 -- Performs a check for the case where the actuals are all simple
3015 -- identifiers that correspond to the formal names, but in the wrong
3016 -- order, which is considered suspicious and cause for a warning.
3018 procedure Check_Prefixed_Call;
3019 -- If the original node is an overloaded call in prefix notation,
3021 -- Try_Object_Operation has already verified that there is a valid
3022 -- interpretation, but the form of the actual can only be determined
3023 -- once the primitive operation is identified.
3026 -- If the actual is missing in a call, insert in the actuals list
3027 -- an instance of the default expression. The insertion is always
3028 -- a named association.
3030 procedure Property_Error
3034 -- Emit an error concerning variable Var with entity Var_Id that has
3035 -- enabled property Prop_Nam when it acts as an actual parameter in a
3036 -- call and the corresponding formal parameter is of mode IN.
3039 -- Check whether T1 and T2, or their full views, are derived from a
3040 -- common type. Used to enforce the restrictions on array conversions
3041 -- of AI95-00246.
3044 -- Predicate to determine whether an actual that is a concatenation
3045 -- will be evaluated statically and does not need a transient scope.
3046 -- This must be determined before the actual is resolved and expanded
3047 -- because if needed the transient scope must be introduced earlier.
3049 ------------------------------
3050 -- Check_Aliased_Parameter --
3051 ------------------------------
3056 begin
3064 else
3071 -- In a generic body assume the worst for generic formals:
3072 -- they can have a constrained partial view (AI05-041).
3078 then
3081 else
3086 else
3098 then
3106 then
3107 Error_Msg_N
3113 --------------------------
3114 -- Check_Argument_Order --
3115 --------------------------
3118 begin
3119 -- Nothing to do if no parameters, or original node is neither a
3120 -- function call nor a procedure call statement (happens in the
3121 -- operator-transformed-to-function call case), or the call does
3122 -- not come from source, or this warning is off.
3124 if not Warn_On_Parameter_Order
3128 then
3132 declare
3135 begin
3136 -- Nothing to do if only one parameter
3142 -- Here if at least two arguments
3144 declare
3150 -- Set True if an out of order case is found
3152 begin
3153 -- Collect identifier names of actuals, fail if any actual is
3154 -- not a simple identifier, and record max length of name.
3160 else
3166 -- If we got this far, all actuals are identifiers and the list
3167 -- of their names is stored in the Actuals array.
3172 -- If we ran out of formals, that's odd, probably an error
3173 -- which will be detected elsewhere, but abandon the search.
3179 -- If name matches and is in order OK
3184 else
3185 -- If no match, see if it is elsewhere in list and if so
3186 -- flag potential wrong order if type is compatible.
3190 and then
3192 then
3198 -- No match
3206 -- If Formals left over, also probably an error, skip warning
3212 -- Here we give the warning if something was out of order
3215 Error_Msg_N
3222 -------------------------
3223 -- Check_Prefixed_Call --
3224 -------------------------
3233 begin
3234 -- Check whether the call is a prefixed call, with or without
3235 -- additional actuals.
3238 or else
3244 then
3247 then
3248 -- Introduce dereference on object in prefix
3250 New_A :=
3258 then
3259 -- Introduce an implicit 'Access in prefix
3262 Error_Msg_NE
3278 --------------------
3279 -- Insert_Default --
3280 --------------------
3286 begin
3287 -- Missing argument in call, nothing to insert
3292 else
3293 -- Note that we do a full New_Copy_Tree, so that any associated
3294 -- Itypes are properly copied. This may not be needed any more,
3295 -- but it does no harm as a safety measure. Defaults of a generic
3296 -- formal may be out of bounds of the corresponding actual (see
3297 -- cc1311b) and an additional check may be required.
3299 Actval :=
3300 New_Copy_Tree
3307 then
3313 then
3316 then
3317 -- If default is a real literal, do not introduce a
3318 -- conversion whose effect may depend on the run-time
3319 -- size of universal real.
3323 else
3334 -- Resolve aggregates with their base type, to avoid scope
3335 -- anomalies: the subtype was first built in the subprogram
3336 -- declaration, and the current call may be nested.
3340 else
3344 else
3347 -- See note above concerning aggregates
3351 then
3354 -- Resolve entities with their own type, which may differ from
3355 -- the type of a reference in a generic context (the view
3356 -- swapping mechanism did not anticipate the re-analysis of
3357 -- default values in calls).
3362 else
3367 -- If default is a tag indeterminate function call, propagate tag
3368 -- to obtain proper dispatching.
3372 then
3378 -- If the default expression raises constraint error, then just
3379 -- silently replace it with an N_Raise_Constraint_Error node, since
3380 -- we already gave the warning on the subprogram spec. If node is
3381 -- already a Raise_Constraint_Error leave as is, to prevent loops in
3382 -- the warnings removal machinery.
3386 then
3394 Assoc :=
3399 -- Case of insertion is first named actual
3403 then
3410 else
3414 else
3418 -- Case of insertion is not first named actual
3420 else
3421 Set_Next_Named_Actual
3433 --------------------
3434 -- Property_Error --
3435 --------------------
3437 procedure Property_Error
3441 is
3442 begin
3444 Error_Msg_NE
3450 -------------------
3451 -- Same_Ancestor --
3452 -------------------
3458 begin
3461 then
3467 then
3474 --------------------------
3475 -- Static_Concatenation --
3476 --------------------------
3479 begin
3486 -- Concatenation is static when both operands are static and
3487 -- the concatenation operator is a predefined one.
3490 and then
3492 and then
3497 declare
3499 begin
3502 and then
3506 else
3512 -- Start of processing for Resolve_Actuals
3514 begin
3515 Check_Argument_Order;
3519 Check_Prefixed_Call;
3528 -- If we have an error in any actual or formal, indicated by a type
3529 -- of Any_Type, then abandon resolution attempt, and set result type
3530 -- to Any_Type. Skip this if the actual is a Raise_Expression, whose
3531 -- type is imposed from context.
3535 then
3542 -- Case where actual is present
3544 -- If the actual is an entity, generate a reference to it now. We
3545 -- do this before the actual is resolved, because a formal of some
3546 -- protected subprogram, or a task discriminant, will be rewritten
3547 -- during expansion, and the source entity reference may be lost.
3552 then
3558 then
3565 -- RM 6.4.1(12): For an out parameter that is passed by
3566 -- copy, the formal parameter object is created, and:
3568 -- * For an access type, the formal parameter is initialized
3569 -- from the value of the actual, without checking that the
3570 -- value satisfies any constraint, any predicate, or any
3571 -- exclusion of the null value.
3573 -- * For a scalar type that has the Default_Value aspect
3574 -- specified, the formal parameter is initialized from the
3575 -- value of the actual, without checking that the value
3576 -- satisfies any constraint or any predicate.
3577 -- I do not understand why this case is included??? this is
3578 -- not a case where an OUT parameter is treated as IN OUT.
3580 -- * For a composite type with discriminants or that has
3581 -- implicit initial values for any subcomponents, the
3582 -- behavior is as for an in out parameter passed by copy.
3584 -- Hence for these cases we generate the read reference now
3585 -- (the write reference will be generated later by
3586 -- Note_Possible_Modification).
3589 and then
3591 or else
3593 and then
3595 or else
3598 or else Is_Partially_Initialized_Type
3600 then
3610 then
3611 -- If style checking mode on, check match of formal name
3619 -- If the formal is Out or In_Out, do not resolve and expand the
3620 -- conversion, because it is subsequently expanded into explicit
3621 -- temporaries and assignments. However, the object of the
3622 -- conversion can be resolved. An exception is the case of tagged
3623 -- type conversion with a class-wide actual. In that case we want
3624 -- the tag check to occur and no temporary will be needed (no
3625 -- representation change can occur) and the parameter is passed by
3626 -- reference, so we go ahead and resolve the type conversion.
3627 -- Another exception is the case of reference to component or
3628 -- subcomponent of a bit-packed array, in which case we want to
3629 -- defer expansion to the point the in and out assignments are
3630 -- performed.
3635 then
3638 then
3639 -- In a view conversion, the conversion must be legal in
3640 -- both directions, and thus both component types must be
3641 -- aliased, or neither (4.6 (8)).
3643 -- The extra rule in 4.6 (24.9.2) seems unduly restrictive:
3644 -- the privacy requirement should not apply to generic
3645 -- types, and should be checked in an instance. ARG query
3646 -- is in order ???
3650 then
3651 Error_Msg_N
3655 -- Comment here??? what set of cases???
3657 elsif
3659 then
3660 -- Check view conv between unrelated by ref array types
3664 then
3665 Error_Msg_N
3669 -- In Ada 2005 mode, check view conversion component
3670 -- type cannot be private, tagged, or volatile. Note
3671 -- that we only apply this to source conversions. The
3672 -- generated code can contain conversions which are
3673 -- not subject to this test, and we cannot extract the
3674 -- component type in such cases since it is not present.
3678 then
3679 declare
3681 Component_Type
3683 begin
3688 then
3689 Error_Msg_N
3700 -- Resolve expression if conversion is all OK
3705 then
3709 -- If the actual is a function call that returns a limited
3710 -- unconstrained object that needs finalization, create a
3711 -- transient scope for it, so that it can receive the proper
3712 -- finalization list.
3717 and then Expander_Active
3719 then
3723 -- A small optimization: if one of the actuals is a concatenation
3724 -- create a block around a procedure call to recover stack space.
3725 -- This alleviates stack usage when several procedure calls in
3726 -- the same statement list use concatenation. We do not perform
3727 -- this wrapping for code statements, where the argument is a
3728 -- static string, and we want to preserve warnings involving
3729 -- sequences of such statements.
3733 and then Expander_Active
3734 and then
3738 then
3742 else
3746 and then
3749 then
3750 Error_Msg_N
3763 -- (Ada 2005: AI-251): If the actual is an allocator whose
3764 -- directly designated type is a class-wide interface, we build
3765 -- an anonymous access type to use it as the type of the
3766 -- allocator. Later, when the subprogram call is expanded, if
3767 -- the interface has a secondary dispatch table the expander
3768 -- will add a type conversion to force the correct displacement
3769 -- of the pointer.
3772 declare
3778 begin
3781 then
3784 Set_Directly_Designated_Type
3789 -- Ada 2005, AI-162:If the actual is an allocator, the
3790 -- innermost enclosing statement is the master of the
3791 -- created object. This needs to be done with expansion
3792 -- enabled only, otherwise the transient scope will not
3793 -- be removed in the expansion of the wrapped construct.
3796 and then Expander_Active
3797 then
3807 -- (Ada 2005): The call may be to a primitive operation of a
3808 -- tagged synchronized type, declared outside of the type. In
3809 -- this case the controlling actual must be converted to its
3810 -- corresponding record type, which is the formal type. The
3811 -- actual may be a subtype, either because of a constraint or
3812 -- because it is a generic actual, so use base type to locate
3813 -- concurrent type.
3820 then
3821 -- If the actual is overloaded, look for an interpretation
3822 -- that has a synchronized type.
3827 else
3828 declare
3832 begin
3837 then
3847 declare
3850 begin
3853 else
3857 -- Tagged synchronized type (case 1): the actual is a
3858 -- concurrent type.
3862 then
3864 Unchecked_Convert_To
3868 -- Tagged synchronized type (case 2): the formal is a
3869 -- concurrent type.
3872 and then Present
3877 then
3880 -- Common case
3882 else
3887 -- Not a synchronized operation
3889 else
3897 -- An actual cannot be an untagged formal incomplete type
3902 then
3903 Error_Msg_N
3909 N_Procedure_Call_Statement)
3910 then
3911 -- In formal mode, check that actual parameters matching
3912 -- formals of tagged types are objects (or ancestor type
3913 -- conversions of objects), not general expressions.
3920 declare
3925 begin
3927 Check_SPARK_05_Restriction
3930 -- In formal mode, the only view conversions are those
3931 -- involving ancestor conversion of an extended type.
3933 elsif not
3939 then
3940 if Ekind_In
3942 then
3943 Check_SPARK_05_Restriction
3946 else
3947 Check_SPARK_05_Restriction
3951 else
3956 else
3960 -- In formal mode, the only view conversions are those
3961 -- involving ancestor conversion of an extended type.
3965 then
3966 Check_SPARK_05_Restriction
3972 -- has warnings suppressed, then we reset Never_Set_In_Source for
3973 -- the calling entity. The reason for this is to catch cases like
3974 -- GNAT.Spitbol.Patterns.Vstring_Var where the called subprogram
3975 -- uses trickery to modify an IN parameter.
3982 then
3986 -- Perform error checks for IN and IN OUT parameters
3990 -- Check unset reference. For scalar parameters, it is clearly
3991 -- wrong to pass an uninitialized value as either an IN or
3992 -- IN-OUT parameter. For composites, it is also clearly an
3993 -- error to pass a completely uninitialized value as an IN
3994 -- parameter, but the case of IN OUT is trickier. We prefer
3995 -- not to give a warning here. For example, suppose there is
3996 -- a routine that sets some component of a record to False.
3997 -- It is perfectly reasonable to make this IN-OUT and allow
3998 -- either initialized or uninitialized records to be passed
3999 -- in this case.
4001 -- For partially initialized composite values, we also avoid
4002 -- warnings, since it is quite likely that we are passing a
4003 -- partially initialized value and only the initialized fields
4004 -- will in fact be read in the subprogram.
4009 then
4013 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
4014 -- actual to a nested call, since this is case of reading an
4015 -- out parameter, which is not allowed.
4020 then
4025 -- Case of OUT or IN OUT parameter
4029 -- For an Out parameter, check for useless assignment. Note
4030 -- that we can't set Last_Assignment this early, because we may
4031 -- kill current values in Resolve_Call, and that call would
4032 -- clobber the Last_Assignment field.
4034 -- Note: call Warn_On_Useless_Assignment before doing the check
4035 -- below for Is_OK_Variable_For_Out_Formal so that the setting
4036 -- of Referenced_As_LHS/Referenced_As_Out_Formal properly
4037 -- reflects the last assignment, not this one.
4044 then
4049 -- Validate the form of the actual. Note that the call to
4050 -- Is_OK_Variable_For_Out_Formal generates the required
4051 -- reference in this case.
4053 -- A call to an initialization procedure for an aggregate
4054 -- component may initialize a nested component of a constant
4055 -- designated object. In this context the object is variable.
4059 then
4063 and then
4066 then
4067 Error_Msg_N
4073 -- What's the following about???
4077 else
4078 Kill_All_Checks;
4087 -- Apply appropriate constraint/predicate checks for IN [OUT] case
4091 -- Apply predicate tests except in certain special cases. Note
4092 -- that it might be more consistent to apply these only when
4093 -- expansion is active (in Exp_Ch6.Expand_Actuals), as we do
4094 -- for the outbound predicate tests ???
4100 -- Apply required constraint checks
4102 -- Gigi looks at the check flag and uses the appropriate types.
4103 -- For now since one flag is used there is an optimization
4104 -- which might not be done in the IN OUT case since Gigi does
4105 -- not do any analysis. More thought required about this ???
4107 -- In fact is this comment obsolete??? doesn't the expander now
4108 -- generate all these tests anyway???
4121 then
4124 -- For view conversions of a discriminated object, apply
4125 -- check to object itself, the conversion alreay has the
4126 -- proper type.
4130 then
4137 then
4143 then
4146 else
4150 -- Ada 2005 (AI-231): Note that the controlling parameter case
4151 -- already existed in Ada 95, which is partially checked
4152 -- elsewhere (see Checks), and we don't want the warning
4153 -- message to differ.
4158 then
4160 Apply_Compile_Time_Constraint_Error
4166 Apply_Compile_Time_Constraint_Error
4175 -- Checks for OUT parameters and IN OUT parameters
4179 -- If there is a type conversion, to make sure the return value
4180 -- meets the constraints of the variable before the conversion.
4184 Apply_Scalar_Range_Check
4186 else
4187 Apply_Range_Check
4191 -- If no conversion apply scalar range checks and length checks
4192 -- base on the subtype of the actual (NOT that of the formal).
4194 else
4199 then
4201 else
4206 -- Note: we do not apply the predicate checks for the case of
4207 -- OUT and IN OUT parameters. They are instead applied in the
4208 -- Expand_Actuals routine in Exp_Ch6.
4211 -- An actual associated with an access parameter is implicitly
4212 -- converted to the anonymous access type of the formal and must
4213 -- satisfy the legality checks for access conversions.
4217 Error_Msg_N
4221 -- If the actual is an access selected component of a variable,
4222 -- the call may modify its designated object. It is reasonable
4223 -- to treat this as a potential modification of the enclosing
4224 -- record, to prevent spurious warnings that it should be
4225 -- declared as a constant, because intuitively programmers
4226 -- regard the designated subcomponent as part of the record.
4231 then
4236 -- Check bad case of atomic/volatile argument (RM C.6(12))
4240 then
4243 then
4244 Error_Msg_NE
4250 then
4251 Error_Msg_NE
4257 -- Check that subprograms don't have improper controlling
4258 -- arguments (RM 3.9.2 (9)).
4260 -- A primitive operation may have an access parameter of an
4261 -- incomplete tagged type, but a dispatching call is illegal
4262 -- if the type is still incomplete.
4268 declare
4270 begin
4274 then
4275 Error_Msg_NE
4289 then
4294 Error_Msg_NE
4298 -- Apply the checks described in 3.10.2(27): if the context is a
4299 -- specific access-to-object, the actual cannot be class-wide.
4300 -- Use base type to exclude access_to_subprogram cases.
4307 and then
4312 -- Disable these checks for call to imported C++ subprograms
4314 and then not
4318 then
4319 Error_Msg_N
4324 Error_Msg_NE
4329 Check_Aliased_Parameter;
4333 -- If it is a named association, treat the selector_name as a
4334 -- proper identifier, and mark the corresponding entity.
4338 -- Ignore reference in SPARK mode, as it refers to an entity not
4339 -- in scope at the point of reference, so the reference should
4340 -- be ignored for computing effects of subprograms.
4342 and then not GNATprove_Mode
4343 then
4356 -- The following checks are only relevant when SPARK_Mode is on as
4357 -- they are not standard Ada legality rule. Internally generated
4358 -- temporaries are ignored.
4363 then
4364 -- An effectively volatile object may act as an actual
4365 -- parameter when the corresponding formal is of a non-scalar
4366 -- volatile type.
4370 then
4373 -- An effectively volatile object may act as an actual
4374 -- parameter in a call to an instance of Unchecked_Conversion.
4379 else
4380 Error_Msg_N
4385 -- Detect an external variable with an enabled property that
4386 -- does not match the mode of the corresponding formal in a
4387 -- procedure call. Functions are not considered because they
4388 -- cannot have effectively volatile formal parameters in the
4389 -- first place.
4395 then
4409 then
4411 Error_Msg_NE
4415 Error_Msg_N
4423 -- Case where actual is not present
4425 else
4426 Insert_Default;
4433 -----------------------
4434 -- Resolve_Allocator --
4435 -----------------------
4447 procedure Check_Allocator_Discrim_Accessibility
4450 -- Check that accessibility level associated with an access discriminant
4451 -- initialized in an allocator by the expression Disc_Exp is not deeper
4452 -- than the level of the allocator type Alloc_Typ. An error message is
4453 -- issued if this condition is violated. Specialized checks are done for
4454 -- the cases of a constraint expression which is an access attribute or
4455 -- an access discriminant.
4458 -- If the allocator is an actual in a call, it is allowed to be class-
4459 -- wide when the context is not because it is a controlling actual.
4461 -------------------------------------------
4462 -- Check_Allocator_Discrim_Accessibility --
4463 -------------------------------------------
4465 procedure Check_Allocator_Discrim_Accessibility
4468 is
4469 begin
4472 then
4473 Error_Msg_N
4476 -- When the expression is an Access attribute the level of the prefix
4477 -- object must not be deeper than that of the allocator's type.
4481 Attribute_Access
4484 then
4485 Error_Msg_N
4487 Disc_Exp);
4489 -- When the expression is an access discriminant the check is against
4490 -- the level of the prefix object.
4496 then
4497 Error_Msg_N
4499 Disc_Exp);
4501 -- All other cases are legal
4503 else
4508 ----------------------------
4509 -- In_Dispatching_Context --
4510 ----------------------------
4515 begin
4521 -- Start of processing for Resolve_Allocator
4523 begin
4524 -- Replace general access with specific type
4534 -- For qualified expression, resolve the expression using the given
4535 -- subtype (nothing to do for type mark, subtype indication)
4540 and then not In_Dispatching_Context
4541 then
4542 Error_Msg_N
4550 -- A qualified expression requires an exact match of the type.
4551 -- Class-wide matching is not allowed.
4556 then
4560 -- Calls to build-in-place functions are not currently supported in
4561 -- allocators for access types associated with a simple storage pool.
4562 -- Supporting such allocators may require passing additional implicit
4563 -- parameters to build-in-place functions (or a significant revision
4564 -- of the current b-i-p implementation to unify the handling for
4565 -- multiple kinds of storage pools). ???
4569 then
4570 declare
4573 begin
4575 and then
4576 Present (Get_Rep_Pragma
4578 then
4579 Error_Msg_N
4586 -- A special accessibility check is needed for allocators that
4587 -- constrain access discriminants. The level of the type of the
4588 -- expression used to constrain an access discriminant cannot be
4589 -- deeper than the type of the allocator (in contrast to access
4590 -- parameters, where the level of the actual can be arbitrary).
4592 -- We can't use Valid_Conversion to perform this check because in
4593 -- general the type of the allocator is unrelated to the type of
4594 -- the access discriminant.
4598 then
4605 then
4608 -- Get the first component expression of the aggregate
4618 else
4622 else
4641 else
4646 else
4655 -- For a subtype mark or subtype indication, freeze the subtype
4657 else
4661 Error_Msg_N
4665 -- A special accessibility check is needed for allocators that
4666 -- constrain access discriminants. The level of the type of the
4667 -- expression used to constrain an access discriminant cannot be
4668 -- deeper than the type of the allocator (in contrast to access
4669 -- parameters, where the level of the actual can be arbitrary).
4670 -- We can't use Valid_Conversion to perform this check because
4671 -- in general the type of the allocator is unrelated to the type
4672 -- of the access discriminant.
4677 then
4687 else
4701 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
4702 -- check that the level of the type of the created object is not deeper
4703 -- than the level of the allocator's access type, since extensions can
4704 -- now occur at deeper levels than their ancestor types. This is a
4705 -- static accessibility level check; a run-time check is also needed in
4706 -- the case of an initialized allocator with a class-wide argument (see
4707 -- Expand_Allocator_Expression).
4711 then
4712 declare
4715 begin
4720 else
4726 then
4729 Error_Msg_N
4738 -- Do not apply Ada 2005 accessibility checks on a class-wide
4739 -- allocator if the type given in the allocator is a formal
4740 -- type. A run-time check will be performed in the instance.
4750 -- Check for allocation from an empty storage pool
4755 -- If the context is an unchecked conversion, as may happen within an
4756 -- inlined subprogram, the allocator is being resolved with its own
4757 -- anonymous type. In that case, if the target type has a specific
4758 -- storage pool, it must be inherited explicitly by the allocator type.
4762 then
4763 Set_Associated_Storage_Pool
4771 -- Check that an allocator with task parts isn't for a nested access
4772 -- type when restriction No_Task_Hierarchy applies.
4776 then
4780 -- An illegal allocator may be rewritten as a raise Program_Error
4781 -- statement.
4785 -- An anonymous access discriminant is the definition of a
4786 -- coextension.
4790 N_Discriminant_Specification
4791 then
4792 declare
4796 begin
4799 -- Ada 2012 AI05-0052: If the designated type of the allocator
4800 -- is limited, then the allocator shall not be used to define
4801 -- the value of an access discriminant unless the discriminated
4802 -- type is immutably limited.
4807 then
4808 Error_Msg_N
4814 -- Avoid marking an allocator as a dynamic coextension if it is
4815 -- within a static construct.
4821 -- Cleanup for potential static coextensions
4823 else
4829 -- Report a simple error: if the designated object is a local task,
4830 -- its body has not been seen yet, and its activation will fail an
4831 -- elaboration check.
4838 then
4844 -- Ada 2012 (AI05-0111-3): Detect an attempt to allocate a task or a
4845 -- type with a task component on a subpool. This action must raise
4846 -- Program_Error at runtime.
4852 then
4864 ---------------------------
4865 -- Resolve_Arithmetic_Op --
4866 ---------------------------
4868 -- Used for resolving all arithmetic operators except exponentiation
4879 -- We do the resolution using the base type, because intermediate values
4880 -- in expressions always are of the base type, not a subtype of it.
4883 -- Returns True if N is in a context that expects "any real type"
4886 -- Return True iff given type is Integer or universal real/integer
4889 -- Choose type of integer literal in fixed-point operation to conform
4890 -- to available fixed-point type. T is the type of the other operand,
4891 -- which is needed to determine the expected type of N.
4894 -- Set operand type to T if universal
4896 -------------------------------
4897 -- Expected_Type_Is_Any_Real --
4898 -------------------------------
4901 begin
4902 -- N is the expression after "delta" in a fixed_point_definition;
4903 -- see RM-3.5.9(6):
4906 N_Decimal_Fixed_Point_Definition,
4908 -- N is one of the bounds in a real_range_specification;
4909 -- see RM-3.5.7(5):
4911 N_Real_Range_Specification,
4913 -- N is the expression of a delta_constraint;
4914 -- see RM-J.3(3):
4916 N_Delta_Constraint);
4919 -----------------------------
4920 -- Is_Integer_Or_Universal --
4921 -----------------------------
4928 begin
4934 else
4940 then
4951 ----------------------------
4952 -- Set_Mixed_Mode_Operand --
4953 ----------------------------
4959 begin
4962 -- A universal integer literal is resolved as standard integer
4963 -- except in the case of a fixed-point result, where we leave it
4964 -- as universal (to be handled by Exp_Fixd later on)
4968 else
4976 then
4977 -- A universal real can appear in a fixed-type context. We resolve
4978 -- the literal with that context, even though this might raise an
4979 -- exception prematurely (the other operand may be zero).
4986 then
4987 -- Integer arg in mixed-mode operation. Resolve with universal
4988 -- type, in case preference rule must be applied.
4994 then
4995 -- Not a mixed-mode operation, resolve with context
5001 -- N may itself be a mixed-mode operation, so use context type
5008 then
5009 -- Must be (fixed * fixed) operation, operand must have one
5010 -- compatible interpretation.
5017 then
5018 -- C * F(X) in a fixed context, where C is a real literal or a
5019 -- fixed-point expression. F must have either a fixed type
5020 -- interpretation or an integer interpretation, but not both.
5027 else
5034 else
5042 -- Reanalyze the literal with the fixed type of the context. If
5043 -- context is Universal_Fixed, we are within a conversion, leave
5044 -- the literal as a universal real because there is no usable
5045 -- fixed type, and the target of the conversion plays no role in
5046 -- the resolution.
5048 declare
5052 begin
5055 else
5061 then
5063 else
5071 else
5076 ----------------------
5077 -- Set_Operand_Type --
5078 ----------------------
5081 begin
5084 then
5089 -- Start of processing for Resolve_Arithmetic_Op
5091 begin
5096 then
5100 -- Special-case for mixed-mode universal expressions or fixed point type
5101 -- operation: each argument is resolved separately. The same treatment
5102 -- is required if one of the operands of a fixed point operation is
5103 -- universal real, since in this case we don't do a conversion to a
5104 -- specific fixed-point type (instead the expander handles the case).
5106 -- Set the type of the node to its universal interpretation because
5107 -- legality checks on an exponentiation operand need the context.
5112 then
5123 or else
5126 then
5131 -- If context is a fixed type and one operand is integer, the other
5132 -- is resolved with the type of the context.
5137 then
5144 then
5148 else
5153 -- Check the rule in RM05-4.5.5(19.1/2) disallowing universal_fixed
5154 -- multiplying operators from being used when the expected type is
5155 -- also universal_fixed. Note that B_Typ will be Universal_Fixed in
5156 -- some cases where the expected type is actually Any_Real;
5157 -- Expected_Type_Is_Any_Real takes care of that case.
5161 then
5165 N_Unchecked_Type_Conversion)
5166 then
5173 else
5176 and then not
5178 N_Unchecked_Type_Conversion)
5179 then
5180 Error_Msg_N
5185 -- The expected type is "any real type" in contexts like
5187 -- type T is delta <universal_fixed-expression> ...
5189 -- in which case we need to set the type to Universal_Real
5190 -- so that static expression evaluation will work properly.
5194 else
5204 then
5209 -- If no previous errors, this is only possible if one operand is
5210 -- overloaded and the context is universal. Resolve as such.
5215 else
5217 and then
5219 then
5223 -- If the context is Universal_Fixed and the operands are also
5224 -- universal fixed, this is an error, unless there is only one
5225 -- applicable fixed_point type (usually Duration).
5233 else
5238 else
5243 -- If one of the arguments was resolved to a non-universal type.
5244 -- label the result of the operation itself with the same type.
5245 -- Do the same for the universal argument, if any.
5257 -- In SPARK, a multiplication or division with operands of fixed point
5258 -- types must be qualified or explicitly converted to identify the
5259 -- result type.
5264 and then
5266 then
5267 Check_SPARK_05_Restriction
5271 -- Set overflow and division checking bit
5278 -- Give warning if explicit division by zero
5282 then
5288 or else
5291 then
5292 -- Specialize the warning message according to the operation.
5293 -- The following warnings are for the case
5298 -- For division, we have two cases, for float division
5299 -- of an unconstrained float type, on a machine where
5300 -- Machine_Overflows is false, we don't get an exception
5301 -- at run-time, but rather an infinity or Nan. The Nan
5302 -- case is pretty obscure, so just warn about infinities.
5306 and then not Machine_Overflows_On_Target
5307 then
5308 Error_Msg_N
5312 -- For all other cases, we get a Constraint_Error
5314 else
5315 Apply_Compile_Time_Constraint_Error
5321 Apply_Compile_Time_Constraint_Error
5326 Apply_Compile_Time_Constraint_Error
5330 -- Division by zero can only happen with division, rem,
5331 -- and mod operations.
5337 -- Otherwise just set the flag to check at run time
5339 else
5344 -- If Restriction No_Implicit_Conditionals is active, then it is
5345 -- violated if either operand can be negative for mod, or for rem
5346 -- if both operands can be negative.
5350 then
5351 declare
5358 -- Set if corresponding operand might be negative
5360 begin
5361 Determine_Range
5365 Determine_Range
5369 -- Check if we will be generating conditionals. There are two
5370 -- cases where that can happen, first for REM, the only case
5371 -- is largest negative integer mod -1, where the division can
5372 -- overflow, but we still have to give the right result. The
5373 -- front end generates a test for this annoying case. Here we
5374 -- just test if both operands can be negative (that's what the
5375 -- expander does, so we match its logic here).
5377 -- The second case is mod where either operand can be negative.
5378 -- In this case, the back end has to generate additional tests.
5381 or else
5383 then
5395 ------------------
5396 -- Resolve_Call --
5397 ------------------
5400 function Same_Or_Aliased_Subprograms
5403 -- Returns True if the subprogram entity S is the same as E or else
5404 -- S is an alias of E.
5406 ---------------------------------
5407 -- Same_Or_Aliased_Subprograms --
5408 ---------------------------------
5410 function Same_Or_Aliased_Subprograms
5413 is
5415 begin
5419 -- Local variables
5433 -- Start of processing for Resolve_Call
5435 begin
5436 -- The context imposes a unique interpretation with type Typ on a
5437 -- procedure or function call. Find the entity of the subprogram that
5438 -- yields the expected type, and propagate the corresponding formal
5439 -- constraints on the actuals. The caller has established that an
5440 -- interpretation exists, and emitted an error if not unique.
5442 -- First deal with the case of a call to an access-to-subprogram,
5443 -- dereference made explicit in Analyze_Call.
5449 else
5450 -- Find the interpretation whose type (a subprogram type) has a
5451 -- return type that is compatible with the context. Analysis of
5452 -- the node has established that one exists.
5471 -- If the prefix is not an entity, then resolve it
5477 -- For an indirect call, we always invalidate checks, since we do not
5478 -- know whether the subprogram is local or global. Yes we could do
5479 -- better here, e.g. by knowing that there are no local subprograms,
5480 -- but it does not seem worth the effort. Similarly, we kill all
5481 -- knowledge of current constant values.
5483 Kill_Current_Values;
5485 -- If this is a procedure call which is really an entry call, do
5486 -- the conversion of the procedure call to an entry call. Protected
5487 -- operations use the same circuitry because the name in the call
5488 -- can be an arbitrary expression with special resolution rules.
5493 then
5497 -- Kill checks and constant values, as above for indirect case
5498 -- Who knows what happens when another task is activated?
5500 Kill_Current_Values;
5503 -- Normal subprogram call with name established in Resolve
5509 -- Otherwise we must have the case of an overloaded call
5511 else
5514 -- Initialize Nam to prevent warning (we know it will be assigned
5515 -- in the loop below, but the compiler does not know that).
5535 then
5536 -- The prefix is a parameterless function call that returns an access
5537 -- to subprogram. If parameters are present in the current call, add
5538 -- add an explicit dereference. We use the base type here because
5539 -- within an instance these may be subtypes.
5541 -- The dereference is added either in Analyze_Call or here. Should
5542 -- be consolidated ???
5551 -- Check that a call to Current_Task does not occur in an entry body
5554 declare
5557 begin
5559 loop
5562 -- Exclude calls that occur within the default of a formal
5563 -- parameter of the entry, since those are evaluated outside
5564 -- of the body.
5571 then
5574 Error_Msg_NE
5588 -- Check that a procedure call does not occur in the context of the
5589 -- entry call statement of a conditional or timed entry call. Note that
5590 -- the case of a call to a subprogram renaming of an entry will also be
5591 -- rejected. The test for N not being an N_Entry_Call_Statement is
5592 -- defensive, covering the possibility that the processing of entry
5593 -- calls might reach this point due to later modifications of the code
5594 -- above.
5599 then
5603 -- Ada 2005 (AI-345): If a procedure_call_statement is used
5604 -- for a procedure_or_entry_call, the procedure_name or
5605 -- procedure_prefix of the procedure_call_statement shall denote
5606 -- an entry renamed by a procedure, or (a view of) a primitive
5607 -- subprogram of a limited interface whose first parameter is
5608 -- a controlling parameter.
5613 then
5614 Error_Msg_N
5619 -- If the SPARK_05 restriction is active, we are not allowed
5620 -- to have a call to a subprogram before we see its completion.
5625 -- Don't flag strange internal calls
5630 -- Only flag calls in extended main source
5635 -- Exclude enumeration literals from this processing
5638 then
5639 Check_SPARK_05_Restriction
5643 -- Check that this is not a call to a protected procedure or entry from
5644 -- within a protected function.
5648 -- Freeze the subprogram name if not in a spec-expression. Note that
5649 -- we freeze procedure calls as well as function calls. Procedure calls
5650 -- are not frozen according to the rules (RM 13.14(14)) because it is
5651 -- impossible to have a procedure call to a non-frozen procedure in
5652 -- pure Ada, but in the code that we generate in the expander, this
5653 -- rule needs extending because we can generate procedure calls that
5654 -- need freezing.
5656 -- In Ada 2012, expression functions may be called within pre/post
5657 -- conditions of subsequent functions or expression functions. Such
5658 -- calls do not freeze when they appear within generated bodies,
5659 -- (including the body of another expression function) which would
5660 -- place the freeze node in the wrong scope. An expression function
5661 -- is frozen in the usual fashion, by the appearance of a real body,
5662 -- or at the end of a declarative part.
5666 and then
5669 then
5673 -- For a predefined operator, the type of the result is the type imposed
5674 -- by context, except for a predefined operation on universal fixed.
5675 -- Otherwise The type of the call is the type returned by the subprogram
5676 -- being called.
5683 -- If the subprogram returns an array type, and the context requires the
5684 -- component type of that array type, the node is really an indexing of
5685 -- the parameterless call. Resolve as such. A pathological case occurs
5686 -- when the type of the component is an access to the array type. In
5687 -- this case the call is truly ambiguous.
5690 and then
5693 or else
5696 and then
5698 then
5699 declare
5704 begin
5707 then
5708 Error_Msg_N
5710 else
5713 -- The called entity may be an explicit dereference, in which
5714 -- case there is no entity to set.
5722 or else
5724 and then
5726 then
5729 -- Indexed call to a parameterless function
5731 Index_Node :=
5733 Prefix =>
5736 else
5737 -- An Ada 2005 prefixed call to a primitive operation
5738 -- whose first parameter is the prefix. This prefix was
5739 -- prepended to the parameter list, which is actually a
5740 -- list of indexes. Remove the prefix in order to build
5741 -- the proper indexed component.
5743 Index_Node :=
5745 Prefix =>
5748 Parameter_Associations =>
5749 New_List
5754 -- Preserve the parenthesis count of the node
5758 -- Since we are correcting a node classification error made
5759 -- by the parser, we call Replace rather than Rewrite.
5773 else
5777 -- In the case where the call is to an overloaded subprogram, Analyze
5778 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
5779 -- such a case Normalize_Actuals needs to be called once more to order
5780 -- the actuals correctly. Otherwise the call will have the ordering
5781 -- given by the last overloaded subprogram whether this is the correct
5782 -- one being called or not.
5789 -- In any case, call is fully resolved now. Reset Overload flag, to
5790 -- prevent subsequent overload resolution if node is analyzed again
5795 -- If we are calling the current subprogram from immediately within its
5796 -- body, then that is the case where we can sometimes detect cases of
5797 -- infinite recursion statically. Do not try this in case restriction
5798 -- No_Recursion is in effect anyway, and do it only for source calls.
5803 -- Check violation of SPARK_05 restriction which does not permit
5804 -- a subprogram body to contain a call to the subprogram directly.
5808 then
5809 Check_SPARK_05_Restriction
5813 -- Issue warning for possible infinite recursion in the absence
5814 -- of the No_Recursion restriction.
5819 then
5820 -- Here we detected and flagged an infinite recursion, so we do
5821 -- not need to test the case below for further warnings. Also we
5822 -- are all done if we now have a raise SE node.
5828 -- If call is to immediately containing subprogram, then check for
5829 -- the case of a possible run-time detectable infinite recursion.
5831 else
5835 -- Although in general case, recursion is not statically
5836 -- checkable, the case of calling an immediately containing
5837 -- subprogram is easy to catch.
5841 -- If the recursive call is to a parameterless subprogram,
5842 -- then even if we can't statically detect infinite
5843 -- recursion, this is pretty suspicious, and we output a
5844 -- warning. Furthermore, we will try later to detect some
5845 -- cases here at run time by expanding checking code (see
5846 -- Detect_Infinite_Recursion in package Exp_Ch6).
5848 -- If the recursive call is within a handler, do not emit a
5849 -- warning, because this is a common idiom: loop until input
5850 -- is correct, catch illegal input in handler and restart.
5856 then
5857 -- For the case of a procedure call. We give the message
5858 -- only if the call is the first statement in a sequence
5859 -- of statements, or if all previous statements are
5860 -- simple assignments. This is simply a heuristic to
5861 -- decrease false positives, without losing too many good
5862 -- warnings. The idea is that these previous statements
5863 -- may affect global variables the procedure depends on.
5864 -- We also exclude raise statements, that may arise from
5865 -- constraint checks and are probably unrelated to the
5866 -- intended control flow.
5870 then
5871 declare
5873 begin
5877 N_Raise_Constraint_Error)
5878 then
5887 -- Do not give warning if we are in a conditional context
5889 declare
5891 begin
5897 then
5902 -- Here warning is to be issued
5918 -- Check obsolescent reference to Ada.Characters.Handling subprogram
5922 -- If subprogram name is a predefined operator, it was given in
5923 -- functional notation. Replace call node with operator node, so
5924 -- that actuals can be resolved appropriately.
5932 then
5938 -- Create a transient scope if the resulting type requires it
5940 -- There are several notable exceptions:
5942 -- a) In init procs, the transient scope overhead is not needed, and is
5943 -- even incorrect when the call is a nested initialization call for a
5944 -- component whose expansion may generate adjust calls. However, if the
5945 -- call is some other procedure call within an initialization procedure
5946 -- (for example a call to Create_Task in the init_proc of the task
5947 -- run-time record) a transient scope must be created around this call.
5949 -- b) Enumeration literal pseudo-calls need no transient scope
5951 -- c) Intrinsic subprograms (Unchecked_Conversion and source info
5952 -- functions) do not use the secondary stack even though the return
5953 -- type may be unconstrained.
5955 -- d) Calls to a build-in-place function, since such functions may
5956 -- allocate their result directly in a target object, and cases where
5957 -- the result does get allocated in the secondary stack are checked for
5958 -- within the specialized Exp_Ch6 procedures for expanding those
5959 -- build-in-place calls.
5961 -- e) If the subprogram is marked Inline_Always, then even if it returns
5962 -- an unconstrained type the call does not require use of the secondary
5963 -- stack. However, inlining will only take place if the body to inline
5964 -- is already present. It may not be available if e.g. the subprogram is
5965 -- declared in a child instance.
5967 -- If this is an initialization call for a type whose construction
5968 -- uses the secondary stack, and it is not a nested call to initialize
5969 -- a component, we do need to create a transient scope for it. We
5970 -- check for this by traversing the type in Check_Initialization_Call.
5976 then
5982 then
5985 elsif Expander_Active
5988 and then
5990 or else
5992 then
5995 -- If the call appears within the bounds of a loop, it will
5996 -- be rewritten and reanalyzed, nothing left to do here.
6003 and then not Within_Init_Proc
6004 then
6008 -- A protected function cannot be called within the definition of the
6009 -- enclosing protected type.
6014 then
6015 Error_Msg_NE
6019 -- Propagate interpretation to actuals, and add default expressions
6020 -- where needed.
6025 -- Overloaded literals are rewritten as function calls, for purpose of
6026 -- resolution. After resolution, we can replace the call with the
6027 -- literal itself.
6033 -- Avoid validation, since it is a static function call
6039 -- If the subprogram is not global, then kill all saved values and
6040 -- checks. This is a bit conservative, since in many cases we could do
6041 -- better, but it is not worth the effort. Similarly, we kill constant
6042 -- values. However we do not need to do this for internal entities
6043 -- (unless they are inherited user-defined subprograms), since they
6044 -- are not in the business of molesting local values.
6046 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
6047 -- kill all checks and values for calls to global subprograms. This
6048 -- takes care of the case where an access to a local subprogram is
6049 -- taken, and could be passed directly or indirectly and then called
6050 -- from almost any context.
6052 -- Note: we do not do this step till after resolving the actuals. That
6053 -- way we still take advantage of the current value information while
6054 -- scanning the actuals.
6056 -- We suppress killing values if we are processing the nodes associated
6057 -- with N_Freeze_Entity nodes. Otherwise the declaration of a tagged
6058 -- type kills all the values as part of analyzing the code that
6059 -- initializes the dispatch tables.
6063 or else Suppress_Value_Tracking_On_Call
6068 then
6069 Kill_Current_Values;
6072 -- If we are warning about unread OUT parameters, this is the place to
6073 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
6074 -- after the above call to Kill_Current_Values (since that call clears
6075 -- the Last_Assignment field of all local variables).
6080 then
6081 declare
6085 begin
6095 then
6105 -- If the subprogram is a primitive operation, check whether or not
6106 -- it is a correct dispatching call.
6110 then
6115 and then not In_Instance
6116 then
6120 -- If this is a dispatching call, generate the appropriate reference,
6121 -- for better source navigation in GPS.
6125 then
6128 -- Normal case, not a dispatching call: generate a call reference
6130 else
6138 -- Check for violation of restriction No_Specific_Termination_Handlers
6139 -- and warn on a potentially blocking call to Abort_Task.
6143 or else
6145 then
6152 -- A call to Ada.Real_Time.Timing_Events.Set_Handler to set a relative
6153 -- timing event violates restriction No_Relative_Delay (AI-0211). We
6154 -- need to check the second argument to determine whether it is an
6155 -- absolute or relative timing event.
6160 then
6164 -- Issue an error for a call to an eliminated subprogram. This routine
6165 -- will not perform the check if the call appears within a default
6166 -- expression.
6170 -- In formal mode, the primitive operations of a tagged type or type
6171 -- extension do not include functions that return the tagged type.
6177 then
6181 -- Implement rule in 12.5.1 (23.3/2): In an instance, if the actual is
6182 -- class-wide and the call dispatches on result in a context that does
6183 -- not provide a tag, the call raises Program_Error.
6186 and then In_Instance
6191 then
6192 -- Verify that none of the formals are controlling
6194 declare
6198 begin
6220 -- Check for calling a function with OUT or IN OUT parameter when the
6221 -- calling context (us right now) is not Ada 2012, so does not allow
6222 -- OUT or IN OUT parameters in function calls.
6227 then
6232 -- Check the dimensions of the actuals in the call. For function calls,
6233 -- propagate the dimensions from the returned type to N.
6237 -- All done, evaluate call and deal with elaboration issues
6242 -- In GNATprove mode, expansion is disabled, but we want to inline some
6243 -- subprograms to facilitate formal verification. Indirect calls through
6244 -- a subprogram type or within a generic cannot be inlined. Inlining is
6245 -- performed only for calls subject to SPARK_Mode on.
6247 if GNATprove_Mode
6250 and then not Inside_A_Generic
6251 then
6258 -- Nothing to do if the subprogram is not eligible for inlining in
6259 -- GNATprove mode.
6263 then
6266 -- Calls cannot be inlined inside assertions, as GNATprove treats
6267 -- assertions as logic expressions.
6274 -- Calls cannot be inlined inside default expressions
6281 -- Inlining should not be performed during pre-analysis
6285 -- With the one-pass inlining technique, a call cannot be
6286 -- inlined if the corresponding body has not been seen yet.
6289 Error_Msg_NE
6294 -- Nothing to do if there is no body to inline, indicating that
6295 -- the subprogram is not suitable for inlining in GNATprove
6296 -- mode.
6301 -- Calls cannot be inlined inside potentially unevaluated
6302 -- expressions, as this would create complex actions inside
6303 -- expressions, that are not handled by GNATprove.
6307 Error_Msg_N
6311 -- Otherwise, inline the call
6313 else
6323 -----------------------------
6324 -- Resolve_Case_Expression --
6325 -----------------------------
6330 begin
6341 -------------------------------
6342 -- Resolve_Character_Literal --
6343 -------------------------------
6349 begin
6350 -- Verify that the character does belong to the type of the context
6355 -- Wide_Wide_Character literals must always be defined, since the set
6356 -- of wide wide character literals is complete, i.e. if a character
6357 -- literal is accepted by the parser, then it is OK for wide wide
6358 -- character (out of range character literals are rejected).
6363 -- Always accept character literal for type Any_Character, which
6364 -- occurs in error situations and in comparisons of literals, both
6365 -- of which should accept all literals.
6370 -- For Standard.Character or a type derived from it, check that the
6371 -- literal is in range.
6378 -- For Standard.Wide_Character or a type derived from it, check that the
6379 -- literal is in range.
6386 -- For Standard.Wide_Wide_Character or a type derived from it, we
6387 -- know the literal is in range, since the parser checked.
6392 -- If the entity is already set, this has already been resolved in a
6393 -- generic context, or comes from expansion. Nothing else to do.
6398 -- Otherwise we have a user defined character type, and we can use the
6399 -- standard visibility mechanisms to locate the referenced entity.
6401 else
6414 -- If we fall through, then the literal does not match any of the
6415 -- entries of the enumeration type. This isn't just a constraint error
6416 -- situation, it is an illegality (see RM 4.2).
6418 Error_Msg_NE
6422 ---------------------------
6423 -- Resolve_Comparison_Op --
6424 ---------------------------
6426 -- Context requires a boolean type, and plays no role in resolution.
6427 -- Processing identical to that for equality operators. The result type is
6428 -- the base type, which matters when pathological subtypes of booleans with
6429 -- limited ranges are used.
6436 begin
6437 -- If this is an intrinsic operation which is not predefined, use the
6438 -- types of its declared arguments to resolve the possibly overloaded
6439 -- operands. Otherwise the operands are unambiguous and specify the
6440 -- expected type.
6445 else
6456 -- Skip remaining processing if already set to Any_Type
6462 -- Deal with other error cases
6466 T = Any_Character
6467 then
6470 else
6478 -- Resolve the operands if types OK
6487 -- In SPARK, ordering operators <, <=, >, >= are not defined for Boolean
6488 -- types or array types except String.
6491 Check_SPARK_05_Restriction
6496 then
6497 Check_SPARK_05_Restriction
6501 -- Check comparison on unordered enumeration
6505 Error_Msg_NE
6510 -- Evaluate the relation (note we do this after the above check since
6511 -- this Eval call may change N to True/False.
6517 -----------------------------------------
6518 -- Resolve_Discrete_Subtype_Indication --
6519 -----------------------------------------
6521 procedure Resolve_Discrete_Subtype_Indication
6524 is
6528 begin
6536 else
6546 Error_Msg_NE
6549 -- Rewrite the constraint as a range of Typ
6550 -- to allow compilation to proceed further.
6562 else
6566 -- Additionally, we must check that the bounds are compatible
6567 -- with the given subtype, which might be different from the
6568 -- type of the context.
6572 -- ??? If the above check statically detects a Constraint_Error
6573 -- it replaces the offending bound(s) of the range R with a
6574 -- Constraint_Error node. When the itype which uses these bounds
6575 -- is frozen the resulting call to Duplicate_Subexpr generates
6576 -- a new temporary for the bounds.
6578 -- Unfortunately there are other itypes that are also made depend
6579 -- on these bounds, so when Duplicate_Subexpr is called they get
6580 -- a forward reference to the newly created temporaries and Gigi
6581 -- aborts on such forward references. This is probably sign of a
6582 -- more fundamental problem somewhere else in either the order of
6583 -- itype freezing or the way certain itypes are constructed.
6585 -- To get around this problem we call Remove_Side_Effects right
6586 -- away if either bounds of R are a Constraint_Error.
6588 declare
6592 begin
6608 -------------------------
6609 -- Resolve_Entity_Name --
6610 -------------------------
6612 -- Used to resolve identifiers and expanded names
6616 -- Denote whether an arbitrary node Nod appears in a check node
6618 function Is_OK_Volatile_Context
6621 -- Determine whether node Context denotes a "non-interfering context"
6622 -- (as defined in SPARK RM 7.1.3(13)) where volatile reference Obj_Ref
6623 -- can safely reside.
6625 ----------------------
6626 -- Appears_In_Check --
6627 ----------------------
6632 begin
6633 -- Climb the parent chain looking for a check node
6640 -- Prevent the search from going too far
6652 ----------------------------
6653 -- Is_OK_Volatile_Context --
6654 ----------------------------
6656 function Is_OK_Volatile_Context
6659 is
6660 begin
6661 -- The volatile object appears on either side of an assignment
6666 -- The volatile object is part of the initialization expression of
6667 -- another object. Ensure that the climb of the parent chain came
6668 -- from the expression side and not from the name side.
6673 then
6676 -- The volatile object appears as an actual parameter in a call to an
6677 -- instance of Unchecked_Conversion whose result is renamed.
6682 then
6685 -- The volatile object appears as the prefix of a name occurring
6686 -- in a non-interfering context.
6689 N_Indexed_Component,
6690 N_Selected_Component,
6691 N_Slice)
6693 and then Is_OK_Volatile_Context
6696 then
6699 -- The volatile object appears as the expression of a type conversion
6700 -- occurring in a non-interfering context.
6703 N_Unchecked_Type_Conversion)
6705 and then Is_OK_Volatile_Context
6708 then
6711 -- Allow references to volatile objects in various checks. This is
6712 -- not a direct SPARK 2014 requirement.
6717 else
6722 -- Local variables
6727 -- Start of processing for Resolve_Entity_Name
6729 begin
6730 -- If garbage from errors, set to Any_Type and return
6737 -- Replace named numbers by corresponding literals. Note that this is
6738 -- the one case where Resolve_Entity_Name must reset the Etype, since
6739 -- it is currently marked as universal.
6749 -- For enumeration literals, we need to make sure that a proper style
6750 -- check is done, since such literals are overloaded, and thus we did
6751 -- not do a style check during the first phase of analysis.
6757 -- Case of subtype name appearing as an operand in expression
6761 -- Allow use of subtype if it is a concurrent type where we are
6762 -- currently inside the body. This will eventually be expanded into a
6763 -- call to Self (for tasks) or _object (for protected objects). Any
6764 -- other use of a subtype is invalid.
6768 then
6771 -- Any other use is an error
6773 else
6774 Error_Msg_N
6778 -- Check discriminant use if entity is discriminant in current scope,
6779 -- i.e. discriminant of record or concurrent type currently being
6780 -- analyzed. Uses in corresponding body are unrestricted.
6785 then
6788 -- A parameterless generic function cannot appear in a context that
6789 -- requires resolution.
6800 then
6803 -- In all other cases, just do the possible static evaluation
6805 else
6806 -- A deferred constant that appears in an expression must have a
6807 -- completion, unless it has been removed by in-place expansion of
6808 -- an aggregate.
6814 and then not In_Spec_Expression
6816 then
6820 then
6822 else
6823 Error_Msg_N (
6831 -- An effectively volatile object subject to enabled properties
6832 -- Async_Writers or Effective_Reads must appear in a specific context.
6833 -- The following checks are only relevant when SPARK_Mode is on as they
6834 -- are not standard Ada legality rules.
6840 and then
6842 then
6843 -- The effectively volatile objects appears in a "non-interfering
6844 -- context" as defined in SPARK RM 7.1.3(13).
6849 -- Assume that references to effectively volatile objects that appear
6850 -- as actual parameters in a procedure call are always legal. The
6851 -- full legality check is done when the actuals are resolved.
6856 -- Otherwise the context causes a side effect with respect to the
6857 -- effectively volatile object.
6859 else
6860 Error_Msg_N
6867 -------------------
6868 -- Resolve_Entry --
6869 -------------------
6881 -- If the bounds of the entry family being called depend on task
6882 -- discriminants, build a new index subtype where a discriminant is
6883 -- replaced with the value of the discriminant of the target task.
6884 -- The target task is the prefix of the entry name in the call.
6886 -----------------------
6887 -- Actual_Index_Type --
6888 -----------------------
6898 -- If the bound is given by a discriminant, replace with a reference
6899 -- to the discriminant of the same name in the target task. If the
6900 -- entry name is the target of a requeue statement and the entry is
6901 -- in the current protected object, the bound to be used is the
6902 -- discriminal of the object (see Apply_Range_Checks for details of
6903 -- the transformation).
6905 -----------------------------
6906 -- Actual_Discriminant_Ref --
6907 -----------------------------
6913 begin
6918 then
6924 then
6925 -- Note: here Bound denotes a discriminant of the corresponding
6926 -- record type tskV, whose discriminal is a formal of the
6927 -- init-proc tskVIP. What we want is the body discriminal,
6928 -- which is associated to the discriminant of the original
6929 -- concurrent type tsk.
6931 return New_Occurrence_Of
6934 else
6935 Ref :=
6945 -- Start of processing for Actual_Index_Type
6947 begin
6950 then
6953 else
6967 -- Start of processing of Resolve_Entry
6969 begin
6970 -- Find name of entry being called, and resolve prefix of name with its
6971 -- own type. The prefix can be overloaded, and the name and signature of
6972 -- the entry must be taken into account.
6976 -- Case of dealing with entry family within the current tasks
6980 else
6986 -- Entry call to an entry (or entry family) in the current task. This
6987 -- is legal even though the task will deadlock. Rewrite as call to
6988 -- current task.
6990 -- This can also be a call to an entry in an enclosing task. If this
6991 -- is a single task, we have to retrieve its name, because the scope
6992 -- of the entry is the task type, not the object. If the enclosing
6993 -- task is a task type, the identity of the task is given by its own
6994 -- self variable.
6996 -- Finally this can be a requeue on an entry of the same task or
6997 -- protected object.
7004 then
7005 -- S is an enclosing task or protected object. The concurrent
7006 -- declaration has been converted into a type declaration, and
7007 -- the object itself has an object declaration that follows
7008 -- the type in the same declarative part.
7020 -- Call to current task. Will be transformed into call to Self
7027 New_N :=
7030 Selector_Name =>
7037 then
7038 -- Use the entry name (which must be unique at this point) to find
7039 -- the prefix that returns the corresponding task/protected type.
7041 declare
7047 begin
7069 -- Up to this point the expression could have been the actual in a
7070 -- simple entry call, and be given by a named association.
7074 else
7080 ------------------------
7081 -- Resolve_Entry_Call --
7082 ------------------------
7094 begin
7095 -- We kill all checks here, because it does not seem worth the effort to
7096 -- do anything better, an entry call is a big operation.
7098 Kill_All_Checks;
7100 -- Processing of the name is similar for entry calls and protected
7101 -- operation calls. Once the entity is determined, we can complete
7102 -- the resolution of the actuals.
7104 -- The selector may be overloaded, in the case of a protected object
7105 -- with overloaded functions. The type of the context is used for
7106 -- resolution.
7111 then
7112 declare
7116 begin
7135 -- Simple entry call
7143 -- Call to member of entry family
7150 -- We cannot in general check the maximum depth of protected entry calls
7151 -- at compile time. But we can tell that any protected entry call at all
7152 -- violates a specified nesting depth of zero.
7158 -- Use context type to disambiguate a protected function that can be
7159 -- called without actuals and that returns an array type, and where the
7160 -- argument list may be an indexing of the returned value.
7165 and then
7171 and then
7172 Covers
7175 then
7176 declare
7179 begin
7180 Index_Node :=
7182 Prefix =>
7186 -- Since we are correcting a node classification error made by the
7187 -- parser, we call Replace rather than Rewrite.
7200 then
7201 -- Rewrite as call to the precondition wrapper, adding the task
7202 -- object to the list of actuals. If the call is to a member of an
7203 -- entry family, include the index as well.
7205 declare
7209 begin
7218 New_Call :=
7220 Name =>
7225 -- Preanalyze and resolve new call. Current procedure is called
7226 -- from Resolve_Call, after which expansion will take place.
7233 -- The operation name may have been overloaded. Order the actuals
7234 -- according to the formals of the resolved entity, and set the return
7235 -- type to that of the operation.
7246 -- Create a call reference to the entry
7254 -- Verify that a procedure call cannot masquerade as an entry
7255 -- call where an entry call is expected.
7260 then
7265 then
7270 then
7275 -- After resolution, entry calls and protected procedure calls are
7276 -- changed into entry calls, for expansion. The structure of the node
7277 -- does not change, so it can safely be done in place. Protected
7278 -- function calls must keep their structure because they are
7279 -- subexpressions.
7283 -- A protected operation that is not a function may modify the
7284 -- corresponding object, and cannot apply to a constant. If this
7285 -- is an internal call, the prefix is the type itself.
7291 then
7292 Error_Msg_N
7294 Entry_Name);
7308 -- Protected functions can return on the secondary stack, in which
7309 -- case we must trigger the transient scope mechanism.
7311 elsif Expander_Active
7313 then
7318 -------------------------
7319 -- Resolve_Equality_Op --
7320 -------------------------
7322 -- Both arguments must have the same type, and the boolean context does
7323 -- not participate in the resolution. The first pass verifies that the
7324 -- interpretation is not ambiguous, and the type of the left argument is
7325 -- correctly set, or is Any_Type in case of ambiguity. If both arguments
7326 -- are strings or aggregates, allocators, or Null, they are ambiguous even
7327 -- though they carry a single (universal) type. Diagnose this case here.
7335 -- The resolution rule for if expressions requires that each such must
7336 -- have a unique type. This means that if several dependent expressions
7337 -- are of a non-null anonymous access type, and the context does not
7338 -- impose an expected type (as can be the case in an equality operation)
7339 -- the expression must be rejected.
7342 -- Attempt to explain the nature of a redundant comparison with True. If
7343 -- the expression N is too complex, this routine issues a general error
7344 -- message.
7347 -- In the case of allocators and access attributes, the context must
7348 -- provide an indication of the specific access type to be used. If
7349 -- one operand is of such a "generic" access type, check whether there
7350 -- is a specific visible access type that has the same designated type.
7351 -- This is semantically dubious, and of no interest to any real code,
7352 -- but c48008a makes it all worthwhile.
7354 -------------------------
7355 -- Check_If_Expression --
7356 -------------------------
7362 begin
7369 then
7375 ------------------------
7376 -- Explain_Redundancy --
7377 ------------------------
7384 begin
7387 -- Strip the operand down to an entity
7389 loop
7392 else
7397 -- The construct denotes an entity
7402 -- Do not generate an error message when the comparison is done
7403 -- against the enumeration literal Standard.True.
7407 -- Build a customized error message
7434 -- The construct is too complex to disect, issue a general message
7436 else
7441 -----------------------------
7442 -- Find_Unique_Access_Type --
7443 -----------------------------
7450 begin
7452 E_Access_Attribute_Type)
7453 then
7457 E_Access_Attribute_Type)
7458 then
7460 else
7472 then
7485 -- Start of processing for Resolve_Equality_Op
7487 begin
7498 T = Any_Character
7499 then
7502 else
7511 then
7520 -- If expressions must have a single type, and if the context does
7521 -- not impose one the dependent expressions cannot be anonymous
7522 -- access types.
7524 -- Why no similar processing for case expressions???
7528 E_Anonymous_Access_Subprogram_Type)
7530 E_Anonymous_Access_Subprogram_Type)
7531 then
7539 -- In SPARK, equality operators = and /= for array types other than
7540 -- String are only defined when, for each index position, the
7541 -- operands have equal static bounds.
7545 -- Protect call to Matching_Static_Array_Bounds to avoid costly
7546 -- operation if not needed.
7554 then
7555 Check_SPARK_05_Restriction
7560 -- If the unique type is a class-wide type then it will be expanded
7561 -- into a dispatching call to the predefined primitive. Therefore we
7562 -- check here for potential violation of such restriction.
7568 if Warn_On_Redundant_Constructs
7573 then
7574 Error_Msg_N -- CODEFIX
7584 -- If this is an inequality, it may be the implicit inequality
7585 -- created for a user-defined operation, in which case the corres-
7586 -- ponding equality operation is not intrinsic, and the operation
7587 -- cannot be constant-folded. Else fold.
7592 or else Is_Intrinsic_Subprogram
7594 then
7600 then
7604 -- Ada 2005: If one operand is an anonymous access type, convert the
7605 -- other operand to it, to ensure that the underlying types match in
7606 -- the back-end. Same for access_to_subprogram, and the conversion
7607 -- verifies that the types are subtype conformant.
7609 -- We apply the same conversion in the case one of the operands is a
7610 -- private subtype of the type of the other.
7612 -- Why the Expander_Active test here ???
7614 if Expander_Active
7615 and then
7617 E_Anonymous_Access_Subprogram_Type)
7619 then
7639 ----------------------------------
7640 -- Resolve_Explicit_Dereference --
7641 ----------------------------------
7649 -- The candidate prefix type, if overloaded
7654 begin
7658 -- A useful optimization: check whether the dereference denotes an
7659 -- element of a container, and if so rewrite it as a call to the
7660 -- corresponding Element function.
7662 -- Disabled for now, on advice of ARG. A more restricted form of the
7663 -- predicate might be acceptable ???
7665 -- if Is_Container_Element (N) then
7666 -- return;
7667 -- end if;
7671 -- Use the context type to select the prefix that has the correct
7672 -- designated type. Keep the first match, which will be the inner-
7673 -- most.
7680 then
7685 -- Remove access types that do not match, but preserve access
7686 -- to subprogram interpretations, in case a further dereference
7687 -- is needed (see below).
7700 else
7701 -- If no interpretation covers the designated type of the prefix,
7702 -- this is the pathological case where not all implementations of
7703 -- the prefix allow the interpretation of the node as a call. Now
7704 -- that the expected type is known, Remove other interpretations
7705 -- from prefix, rewrite it as a call, and resolve again, so that
7706 -- the proper call node is generated.
7717 New_N :=
7719 Name =>
7730 -- If not overloaded, resolve P with its own type
7732 else
7740 -- If the designated type is a packed unconstrained array type, and the
7741 -- explicit dereference is not in the context of an attribute reference,
7742 -- then we must compute and set the actual subtype, since it is needed
7743 -- by Gigi. The reason we exclude the attribute case is that this is
7744 -- handled fine by Gigi, and in fact we use such attributes to build the
7745 -- actual subtype. We also exclude generated code (which builds actual
7746 -- subtypes directly if they are needed).
7753 then
7757 -- Note: No Eval processing is required for an explicit dereference,
7758 -- because such a name can never be static.
7762 -------------------------------------
7763 -- Resolve_Expression_With_Actions --
7764 -------------------------------------
7767 begin
7770 -- If N has no actions, and its expression has been constant folded,
7771 -- then rewrite N as just its expression. Note, we can't do this in
7772 -- the general case of Is_Empty_List (Actions (N)) as this would cause
7773 -- Expression (N) to be expanded again.
7777 then
7782 ----------------------------------
7783 -- Resolve_Generalized_Indexing --
7784 ----------------------------------
7792 begin
7793 -- In ASIS mode, propagate the information about the indices back to
7794 -- to the original indexing node. The generalized indexing is either
7795 -- a function call, or a dereference of one. The actuals include the
7796 -- prefix of the original node, which is the container expression.
7805 loop
7816 else
7822 ---------------------------
7823 -- Resolve_If_Expression --
7824 ---------------------------
7833 begin
7838 -- When the "then" expression is of a scalar subtype different from the
7839 -- result subtype, then insert a conversion to ensure the generation of
7840 -- a constraint check. The same is done for the else part below, again
7841 -- comparing subtypes rather than base types.
7845 then
7850 -- If ELSE expression present, just resolve using the determined type
7858 then
7863 -- If no ELSE expression is present, root type must be Standard.Boolean
7864 -- and we provide a Standard.True result converted to the appropriate
7865 -- Boolean type (in case it is a derived boolean type).
7868 Else_Expr :=
7873 else
7882 -------------------------------
7883 -- Resolve_Indexed_Component --
7884 -------------------------------
7892 begin
7900 -- Use the context type to select the prefix that yields the correct
7901 -- component type.
7903 declare
7910 begin
7917 and then
7918 Covers
7921 then
7930 else
7936 else
7947 else
7954 -- If prefix is access type, dereference to get real array type.
7955 -- Note: we do not apply an access check because the expander always
7956 -- introduces an explicit dereference, and the check will happen there.
7962 -- If name was overloaded, set component type correctly now
7963 -- If a misplaced call to an entry family (which has no index types)
7964 -- return. Error will be diagnosed from calling context.
7968 else
7975 -- The prefix may have resolved to a string literal, in which case its
7976 -- etype has a special representation. This is only possible currently
7977 -- if the prefix is a static concatenation, written in functional
7978 -- notation.
7983 else
7990 else
8001 -- Do not generate the warning on suspicious index if we are analyzing
8002 -- package Ada.Tags; otherwise we will report the warning with the
8003 -- Prims_Ptr field of the dispatch table.
8006 or else not
8008 Ada_Tags)
8009 then
8014 -- If the array type is atomic, and the component is not atomic, then
8015 -- this is worth a warning, since we have a situation where the access
8016 -- to the component may cause extra read/writes of the atomic array
8017 -- object, or partial word accesses, which could be unexpected.
8023 and then Has_Atomic_Components
8026 then
8034 -----------------------------
8035 -- Resolve_Integer_Literal --
8036 -----------------------------
8039 begin
8044 --------------------------------
8045 -- Resolve_Intrinsic_Operator --
8046 --------------------------------
8055 -- If the operand is a literal, it cannot be the expression in a
8056 -- conversion. Use a qualified expression instead.
8061 begin
8063 Res :=
8069 else
8076 -- Start of processing for Resolve_Intrinsic_Operator
8078 begin
8079 -- We must preserve the original entity in a generic setting, so that
8080 -- the legality of the operation can be verified in an instance.
8095 -- If the result or operand types are private, rewrite with unchecked
8096 -- conversions on the operands and the result, to expose the proper
8097 -- underlying numeric type.
8102 then
8104 -- Unchecked_Convert_To (Btyp, Left_Opnd (N));
8105 -- What on earth is this commented out fragment of code???
8109 else
8130 then
8131 -- Add explicit conversion where needed, and save interpretations in
8132 -- case operands are overloaded.
8139 else
8145 else
8155 else
8160 --------------------------------------
8161 -- Resolve_Intrinsic_Unary_Operator --
8162 --------------------------------------
8164 procedure Resolve_Intrinsic_Unary_Operator
8167 is
8172 begin
8191 else
8196 ------------------------
8197 -- Resolve_Logical_Op --
8198 ------------------------
8203 begin
8206 -- Predefined operations on scalar types yield the base type. On the
8207 -- other hand, logical operations on arrays yield the type of the
8208 -- arguments (and the context).
8212 else
8216 -- The following test is required because the operands of the operation
8217 -- may be literals, in which case the resulting type appears to be
8218 -- compatible with a signed integer type, when in fact it is compatible
8219 -- only with modular types. If the context itself is universal, the
8220 -- operation is illegal.
8228 Error_Msg_N
8236 then
8240 -- Replace AND by AND THEN, or OR by OR ELSE, if Short_Circuit_And_Or
8241 -- is active and the result type is standard Boolean (do not mess with
8242 -- ops that return a nonstandard Boolean type, because something strange
8243 -- is going on).
8245 -- Note: you might expect this replacement to be done during expansion,
8246 -- but that doesn't work, because when the pragma Short_Circuit_And_Or
8247 -- is used, no part of the right operand of an "and" or "or" operator
8248 -- should be executed if the left operand would short-circuit the
8249 -- evaluation of the corresponding "and then" or "or else". If we left
8250 -- the replacement to expansion time, then run-time checks associated
8251 -- with such operands would be evaluated unconditionally, due to being
8252 -- before the condition prior to the rewriting as short-circuit forms
8253 -- during expansion.
8255 if Short_Circuit_And_Or
8258 then
8266 -- Case of OR changed to OR ELSE
8268 else
8276 -- Return now, since analysis of the rewritten ops will take care of
8277 -- other reference bookkeeping and expression folding.
8292 -- In SPARK, logical operations AND, OR and XOR for arrays are defined
8293 -- only when both operands have same static lower and higher bounds. Of
8294 -- course the types have to match, so only check if operands are
8295 -- compatible and the node itself has no errors.
8299 then
8300 declare
8304 begin
8305 -- Protect call to Matching_Static_Array_Bounds to avoid costly
8306 -- operation if not needed.
8313 then
8314 Check_SPARK_05_Restriction
8323 ---------------------------
8324 -- Resolve_Membership_Op --
8325 ---------------------------
8327 -- The context can only be a boolean type, and does not determine the
8328 -- arguments. Arguments should be unambiguous, but the preference rule for
8329 -- universal types applies.
8339 -- Analysis has determined a unique type for the left operand. Use it to
8340 -- resolve the disjuncts.
8342 ----------------------------
8343 -- Resolve_Set_Membership --
8344 ----------------------------
8350 begin
8356 -- Alternative is an expression, a range
8357 -- or a subtype mark.
8361 then
8368 -- Check for duplicates for discrete case
8371 declare
8380 begin
8381 -- Loop checking duplicates. This is quadratic, but giant sets
8382 -- are unlikely in this context so it's a reasonable choice.
8389 N_Character_Literal)
8391 then
8409 -- Start of processing for Resolve_Membership_Op
8411 begin
8417 Resolve_Set_Membership;
8421 and then
8423 or else
8426 then
8429 -- Ada 2005 (AI-251): Support the following case:
8431 -- type I is interface;
8432 -- type T is tagged ...
8434 -- function Test (O : I'Class) is
8435 -- begin
8436 -- return O in T'Class.
8437 -- end Test;
8439 -- In this case we have nothing else to do. The membership test will be
8440 -- done at run time.
8447 then
8449 else
8453 -- If mixed-mode operations are present and operands are all literal,
8454 -- the only interpretation involves Duration, which is probably not
8455 -- the intention of the programmer.
8470 then
8476 else
8481 -- Here after resolving membership operation
8489 ------------------
8490 -- Resolve_Null --
8491 ------------------
8496 begin
8497 -- Handle restriction against anonymous null access values This
8498 -- restriction can be turned off using -gnatdj.
8500 -- Ada 2005 (AI-231): Remove restriction
8503 and then not Debug_Flag_J
8506 then
8507 -- In the common case of a call which uses an explicitly null value
8508 -- for an access parameter, give specialized error message.
8511 Error_Msg_N
8514 -- Standard message for all other cases (are there any?)
8516 else
8517 Error_Msg_N
8522 -- Ada 2005 (AI-231): Generate the null-excluding check in case of
8523 -- assignment to a null-excluding object
8528 then
8530 Insert_Action
8535 else
8542 -- In a distributed context, null for a remote access to subprogram may
8543 -- need to be replaced with a special record aggregate. In this case,
8544 -- return after having done the transformation.
8549 then
8553 -- The null literal takes its type from the context
8558 -----------------------
8559 -- Resolve_Op_Concat --
8560 -----------------------
8564 -- We wish to avoid deep recursion, because concatenations are often
8565 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
8566 -- operands nonrecursively until we find something that is not a simple
8567 -- concatenation (A in this case). We resolve that, and then walk back
8568 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
8569 -- to do the rest of the work at each level. The Parent pointers allow
8570 -- us to avoid recursion, and thus avoid running out of memory. See also
8571 -- Sem_Ch4.Analyze_Concatenation, where a similar approach is used.
8576 begin
8577 -- The following code is equivalent to:
8579 -- Resolve_Op_Concat_First (NN, Typ);
8580 -- Resolve_Op_Concat_Arg (N, ...);
8581 -- Resolve_Op_Concat_Rest (N, Typ);
8583 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
8584 -- operand is a concatenation.
8586 -- Walk down left operands
8588 loop
8597 -- Now (given the above example) NN is A&B and Op1 is A
8599 -- First resolve Op1 ...
8603 -- ... then walk NN back up until we reach N (where we started), calling
8604 -- Resolve_Op_Concat_Rest along the way.
8606 loop
8613 Check_SPARK_05_Restriction
8618 ---------------------------
8619 -- Resolve_Op_Concat_Arg --
8620 ---------------------------
8622 procedure Resolve_Op_Concat_Arg
8627 is
8631 begin
8633 if Is_Comp
8637 then
8639 else
8643 -- If both Array & Array and Array & Component are visible, there is a
8644 -- potential ambiguity that must be reported.
8649 then
8653 -- If the operation is user-defined and not overloaded use its
8654 -- profile. The operation may be a renaming, in which case it has
8655 -- been rewritten, and we want the original profile.
8660 then
8662 Etype
8666 -- Otherwise an aggregate may match both the array type and the
8667 -- component type.
8669 else
8674 else
8678 then
8679 declare
8684 begin
8689 -- Special-case the error message when the overloading is
8690 -- caused by a function that yields an array and can be
8691 -- called without parameters.
8696 Error_Msg_NE
8698 Error_Msg_NE
8702 else
8710 or else
8712 then
8713 Error_Msg_N -- CODEFIX
8731 else
8736 else
8740 -- Concatenation is restricted in SPARK: each operand must be either a
8741 -- string literal, the name of a string constant, a static character or
8742 -- string expression, or another concatenation. Arg cannot be a
8743 -- concatenation here as callers of Resolve_Op_Concat_Arg call it
8744 -- separately on each final operand, past concatenation operations.
8748 Check_SPARK_05_Restriction
8756 then
8757 Check_SPARK_05_Restriction
8761 -- Do not issue error on an operand that is neither a character nor a
8762 -- string, as the error is issued in Resolve_Op_Concat.
8764 else
8771 -----------------------------
8772 -- Resolve_Op_Concat_First --
8773 -----------------------------
8780 begin
8781 -- The parser folds an enormous sequence of concatenations of string
8782 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
8783 -- in the right operand. If the expression resolves to a predefined "&"
8784 -- operator, all is well. Otherwise, the parser's folding is wrong, so
8785 -- we give an error. See P_Simple_Expression in Par.Ch4.
8790 then
8805 ----------------------------
8806 -- Resolve_Op_Concat_Rest --
8807 ----------------------------
8813 begin
8822 -- If this is not a static concatenation, but the result is a string
8823 -- type (and not an array of strings) ensure that static string operands
8824 -- have their subtypes properly constructed.
8828 then
8834 ----------------------
8835 -- Resolve_Op_Expon --
8836 ----------------------
8841 begin
8842 -- Catch attempts to do fixed-point exponentiation with universal
8843 -- operands, which is a case where the illegality is not caught during
8844 -- normal operator analysis. This is not done in preanalysis mode
8845 -- since the tree is not fully decorated during preanalysis.
8856 then
8866 then
8873 then
8877 -- We do the resolution using the base type, because intermediate values
8878 -- in expressions are always of the base type, not a subtype of it.
8883 -- For integer types, right argument must be in Natural range
8898 -- Evaluate the exponentiation operator for dimensioned type
8901 else
8905 -- Set overflow checking bit. Much cleverer code needed here eventually
8906 -- and perhaps the Resolve routines should be separated for the various
8907 -- arithmetic operations, since they will need different processing. ???
8916 --------------------
8917 -- Resolve_Op_Not --
8918 --------------------
8924 -- This function determines if the parent node is a boolean operator or
8925 -- operation (comparison op, membership test, or short circuit form) and
8926 -- the not in question is the left operand of this operation. Note that
8927 -- if the not is in parens, then false is returned.
8929 -----------------------
8930 -- Parent_Is_Boolean --
8931 -----------------------
8934 begin
8938 else
8940 when N_Op_And |
8941 N_Op_Eq |
8942 N_Op_Ge |
8943 N_Op_Gt |
8944 N_Op_Le |
8945 N_Op_Lt |
8946 N_Op_Ne |
8947 N_Op_Or |
8948 N_Op_Xor |
8949 N_In |
8950 N_Not_In |
8951 N_And_Then |
8952 N_Or_Else =>
8962 -- Start of processing for Resolve_Op_Not
8964 begin
8965 -- Predefined operations on scalar types yield the base type. On the
8966 -- other hand, logical operations on arrays yield the type of the
8967 -- arguments (and the context).
8971 else
8975 -- Straightforward case of incorrect arguments
8982 -- Special case of probable missing parens
8986 Error_Msg_N
8989 else
8990 Error_Msg_N
8997 -- OK resolution of NOT
8999 else
9000 -- Warn if non-boolean types involved. This is a case like not a < b
9001 -- where a and b are modular, where we will get (not a) < b and most
9002 -- likely not (a < b) was intended.
9004 if Warn_On_Questionable_Missing_Parens
9006 and then Parent_Is_Boolean
9007 then
9011 -- Warn on double negation if checking redundant constructs
9013 if Warn_On_Redundant_Constructs
9018 then
9022 -- Complete resolution and evaluation of NOT
9032 -----------------------------
9033 -- Resolve_Operator_Symbol --
9034 -----------------------------
9036 -- Nothing to be done, all resolved already
9042 begin
9046 ----------------------------------
9047 -- Resolve_Qualified_Expression --
9048 ----------------------------------
9056 begin
9059 -- Protect call to Matching_Static_Array_Bounds to avoid costly
9060 -- operation if not needed.
9067 then
9068 Check_SPARK_05_Restriction
9072 -- A qualified expression requires an exact match of the type, class-
9073 -- wide matching is not allowed. However, if the qualifying type is
9074 -- specific and the expression has a class-wide type, it may still be
9075 -- okay, since it can be the result of the expansion of a call to a
9076 -- dispatching function, so we also have to check class-wideness of the
9077 -- type of the expression's original node.
9080 or else
9084 then
9088 -- If the target type is unconstrained, then we reset the type of the
9089 -- result from the type of the expression. For other cases, the actual
9090 -- subtype of the expression is the target type.
9094 then
9101 -- If we still have a qualified expression after the static evaluation,
9102 -- then apply a scalar range check if needed. The reason that we do this
9103 -- after the Eval call is that otherwise, the application of the range
9104 -- check may convert an illegal static expression and result in warning
9105 -- rather than giving an error (e.g Integer'(Integer'Last + 1)).
9112 ------------------------------
9113 -- Resolve_Raise_Expression --
9114 ------------------------------
9117 begin
9121 else
9126 -------------------
9127 -- Resolve_Range --
9128 -------------------
9135 -- Returns True if N is of the form X'First .. X'Last where X is the
9136 -- same entity for both attributes.
9138 --------------------
9139 -- First_Last_Ref --
9140 --------------------
9146 begin
9151 then
9152 declare
9155 begin
9159 then
9168 -- Start of processing for Resolve_Range
9170 begin
9175 -- Check for inappropriate range on unordered enumeration type
9179 -- Exclude X'First .. X'Last if X is the same entity for both
9181 and then not First_Last_Ref
9182 then
9184 Error_Msg_NE
9191 -- We have to check the bounds for being within the base range as
9192 -- required for a non-static context. Normally this is automatic and
9193 -- done as part of evaluating expressions, but the N_Range node is an
9194 -- exception, since in GNAT we consider this node to be a subexpression,
9195 -- even though in Ada it is not. The circuit in Sem_Eval could check for
9196 -- this, but that would put the test on the main evaluation path for
9197 -- expressions.
9202 -- Check for an ambiguous range over character literals. This will
9203 -- happen with a membership test involving only literals.
9211 -- If bounds are static, constant-fold them, so size computations are
9212 -- identical between front-end and back-end. Do not perform this
9213 -- transformation while analyzing generic units, as type information
9214 -- would be lost when reanalyzing the constant node in the instance.
9227 --------------------------
9228 -- Resolve_Real_Literal --
9229 --------------------------
9234 begin
9235 -- Special processing for fixed-point literals to make sure that the
9236 -- value is an exact multiple of small where this is required. We skip
9237 -- this for the universal real case, and also for generic types.
9243 then
9244 declare
9251 begin
9252 -- Case of literal is not an exact multiple of the Small
9256 -- For a source program literal for a decimal fixed-point type,
9257 -- this is statically illegal (RM 4.9(36)).
9262 then
9266 -- Generate a warning if literal from source
9269 and then Warn_On_Bad_Fixed_Value
9270 then
9271 Error_Msg_N
9273 N);
9276 -- Replace literal by a value that is the exact representation
9277 -- of a value of the type, i.e. a multiple of the small value,
9278 -- by truncation, since Machine_Rounds is false for all GNAT
9279 -- fixed-point types (RM 4.9(38)).
9289 -- In all cases, set the corresponding integer field
9295 -- Now replace the actual type by the expected type as usual
9301 -----------------------
9302 -- Resolve_Reference --
9303 -----------------------
9308 begin
9309 -- Replace general access with specific type
9317 -- If we are taking the reference of a volatile entity, then treat it as
9318 -- a potential modification of this entity. This is too conservative,
9319 -- but necessary because remove side effects can cause transformations
9320 -- of normal assignments into reference sequences that otherwise fail to
9321 -- notice the modification.
9328 --------------------------------
9329 -- Resolve_Selected_Component --
9330 --------------------------------
9345 -- Check whether this is the initialization of a component within an
9346 -- init proc (by assignment or call to another init proc). If true,
9347 -- there is no need for a discriminant check.
9349 --------------------
9350 -- Init_Component --
9351 --------------------
9354 begin
9355 return Inside_Init_Proc
9361 -- Start of processing for Resolve_Selected_Component
9363 begin
9366 -- Use the context type to select the prefix that has a selector
9367 -- of the correct name and type.
9375 else
9379 -- Locate selected component. For a private prefix the selector
9380 -- can denote a discriminant.
9384 -- The visible components of a class-wide type are those of
9385 -- the root type.
9395 then
9402 else
9406 Error_Msg_N
9411 else
9414 -- There may be an implicit dereference. Retrieve
9415 -- designated record type.
9419 else
9425 -- Resolution chooses the new interpretation.
9426 -- Find the component with the right name.
9431 loop
9448 -- There must be a legal interpretation at this point
9455 else
9456 -- Resolve prefix with its type
9461 -- Generate cross-reference. We needed to wait until full overloading
9462 -- resolution was complete to do this, since otherwise we can't tell if
9463 -- we are an lvalue or not.
9467 else
9471 -- If prefix is an access type, the node will be transformed into an
9472 -- explicit dereference during expansion. The type of the node is the
9473 -- designated type of that of the prefix.
9478 else
9482 -- Set flag for expander if discriminant check required
9489 and then not Init_Component
9490 then
9498 -- If the prefix is a record conversion, this may be a renamed
9499 -- discriminant whose bounds differ from those of the original
9500 -- one, so we must ensure that a range check is performed.
9505 then
9509 -- Note: No Eval processing is required, because the prefix is of a
9510 -- record type, or protected type, and neither can possibly be static.
9512 -- If the record type is atomic, and the component is non-atomic, then
9513 -- this is worth a warning, since we have a situation where the access
9514 -- to the component may cause extra read/writes of the atomic array
9515 -- object, or partial word accesses, both of which may be unexpected.
9521 then
9522 Error_Msg_N
9525 Error_Msg_N
9533 -------------------
9534 -- Resolve_Shift --
9535 -------------------
9542 begin
9543 -- We do the resolution using the base type, because intermediate values
9544 -- in expressions always are of the base type, not a subtype of it.
9557 ---------------------------
9558 -- Resolve_Short_Circuit --
9559 ---------------------------
9566 begin
9567 -- Ensure all actions associated with the left operand (e.g.
9568 -- finalization of transient controlled objects) are fully evaluated
9569 -- locally within an expression with actions. This is particularly
9570 -- helpful for coverage analysis. However this should not happen in
9571 -- generics.
9574 declare
9576 begin
9584 -- Set Comes_From_Source on L to preserve warnings for unset
9585 -- reference.
9594 -- Check for issuing warning for always False assert/check, this happens
9595 -- when assertions are turned off, in which case the pragma Assert/Check
9596 -- was transformed into:
9598 -- if False and then <condition> then ...
9600 -- and we detect this pattern
9602 if Warn_On_Assertion_Failure
9609 then
9610 declare
9613 begin
9614 -- Special handling of Asssert pragma
9618 then
9619 declare
9621 Original_Node
9622 (Expression
9625 begin
9626 -- Don't warn if original condition is explicit False,
9627 -- since obviously the failure is expected in this case.
9631 then
9634 -- Issue warning. We do not want the deletion of the
9635 -- IF/AND-THEN to take this message with it. We achieve this
9636 -- by making sure that the expanded code points to the Sloc
9637 -- of the expression, not the original pragma.
9639 else
9640 -- Note: Use Error_Msg_F here rather than Error_Msg_N.
9641 -- The source location of the expression is not usually
9642 -- the best choice here. For example, it gets located on
9643 -- the last AND keyword in a chain of boolean expressiond
9644 -- AND'ed together. It is best to put the message on the
9645 -- first character of the assertion, which is the effect
9646 -- of the First_Node call here.
9648 Error_Msg_F
9650 Expression
9655 -- Similar processing for Check pragma
9659 then
9660 -- Don't want to warn if original condition is explicit False
9662 declare
9664 Original_Node
9665 (Expression
9667 begin
9670 then
9673 -- Post warning
9675 else
9676 -- Again use Error_Msg_F rather than Error_Msg_N, see
9677 -- comment above for an explanation of why we do this.
9679 Error_Msg_F
9681 Expression
9689 -- Continue with processing of short circuit
9698 -------------------
9699 -- Resolve_Slice --
9700 -------------------
9709 begin
9712 -- Use the context type to select the prefix that yields the correct
9713 -- array type.
9715 declare
9722 begin
9730 then
9738 else
9743 else
9754 else
9764 -- If the prefix is an access to an unconstrained array, we must use
9765 -- the actual subtype of the object to perform the index checks. The
9766 -- object denoted by the prefix is implicit in the node, so we build
9767 -- an explicit representation for it in order to compute the actual
9768 -- subtype.
9773 declare
9777 begin
9788 then
9791 -- If the name is a selected component that depends on discriminants,
9792 -- build an actual subtype for it. This can happen only when the name
9793 -- itself is overloaded; otherwise the actual subtype is created when
9794 -- the selected component is analyzed.
9797 and then Full_Analysis
9799 then
9800 declare
9803 begin
9808 -- Maybe this should just be "else", instead of checking for the
9809 -- specific case of slice??? This is needed for the case where the
9810 -- prefix is an Image attribute, which gets expanded to a slice, and so
9811 -- has a constrained subtype which we want to use for the slice range
9812 -- check applied below (the range check won't get done if the
9813 -- unconstrained subtype of the 'Image is used).
9819 -- Obtain the type of the array index
9823 else
9827 -- If name was overloaded, set slice type correctly now
9831 -- Handle the generation of a range check that compares the array index
9832 -- against the discrete_range. The check is not applied to internally
9833 -- built nodes associated with the expansion of dispatch tables. Check
9834 -- that Ada.Tags has already been loaded to avoid extra dependencies on
9835 -- the unit.
9837 if Tagged_Type_Expansion
9843 then
9846 -- The discrete_range is specified by a subtype indication. Create a
9847 -- shallow copy and inherit the type, parent and source location from
9848 -- the discrete_range. This ensures that the range check is inserted
9849 -- relative to the slice and that the runtime exception points to the
9850 -- proper construct.
9859 -- The discrete_range is a regular range. Resolve the bounds and remove
9860 -- their side effects.
9862 else
9879 -- Check bad use of type with predicates
9881 declare
9884 begin
9887 then
9889 else
9894 Bad_Predicated_Subtype_Use
9899 -- Otherwise here is where we check suspicious indexes
9910 ----------------------------
9911 -- Resolve_String_Literal --
9912 ----------------------------
9923 begin
9924 -- For a string appearing in a concatenation, defer creation of the
9925 -- string_literal_subtype until the end of the resolution of the
9926 -- concatenation, because the literal may be constant-folded away. This
9927 -- is a useful optimization for long concatenation expressions.
9929 -- If the string is an aggregate built for a single character (which
9930 -- happens in a non-static context) or a is null string to which special
9931 -- checks may apply, we build the subtype. Wide strings must also get a
9932 -- string subtype if they come from a one character aggregate. Strings
9933 -- generated by attributes might be static, but it is often hard to
9934 -- determine whether the enclosing context is static, so we generate
9935 -- subtypes for them as well, thus losing some rarer optimizations ???
9936 -- Same for strings that come from a static conversion.
9938 Need_Check :=
9947 -- If the resolving type is itself a string literal subtype, we can just
9948 -- reuse it, since there is no point in creating another.
9954 and then not Need_Check
9956 N_Attribute_Reference,
9957 N_Qualified_Expression,
9958 N_Type_Conversion)
9959 then
9962 -- Do not generate a string literal subtype for the default expression
9963 -- of a formal parameter in GNATprove mode. This is because the string
9964 -- subtype is associated with the freezing actions of the subprogram,
9965 -- however freezing is disabled in GNATprove mode and as a result the
9966 -- subtype is unavailable.
9968 elsif GNATprove_Mode
9970 then
9973 -- Otherwise we must create a string literal subtype. Note that the
9974 -- whole idea of string literal subtypes is simply to avoid the need
9975 -- for building a full fledged array subtype for each literal.
9977 else
9983 or else Need_Check
9984 then
9991 then
9997 -- The validity of a null string has been checked in the call to
9998 -- Eval_String_Literal.
10003 -- Always accept string literal with component type Any_Character, which
10004 -- occurs in error situations and in comparisons of literals, both of
10005 -- which should accept all literals.
10010 -- If the type is bit-packed, then we always transform the string
10011 -- literal into a full fledged aggregate.
10016 -- Deal with cases of Wide_Wide_String, Wide_String, and String
10018 else
10019 -- For Standard.Wide_Wide_String, or any other type whose component
10020 -- type is Standard.Wide_Wide_Character, we know that all the
10021 -- characters in the string must be acceptable, since the parser
10022 -- accepted the characters as valid character literals.
10027 -- For the case of Standard.String, or any other type whose component
10028 -- type is Standard.Character, we must make sure that there are no
10029 -- wide characters in the string, i.e. that it is entirely composed
10030 -- of characters in range of type Character.
10032 -- If the string literal is the result of a static concatenation, the
10033 -- test has already been performed on the components, and need not be
10034 -- repeated.
10038 then
10042 -- If we are out of range, post error. This is one of the
10043 -- very few places that we place the flag in the middle of
10044 -- a token, right under the offending wide character. Not
10045 -- quite clear if this is right wrt wide character encoding
10046 -- sequences, but it's only an error message.
10048 Error_Msg
10055 -- For the case of Standard.Wide_String, or any other type whose
10056 -- component type is Standard.Wide_Character, we must make sure that
10057 -- there are no wide characters in the string, i.e. that it is
10058 -- entirely composed of characters in range of type Wide_Character.
10060 -- If the string literal is the result of a static concatenation,
10061 -- the test has already been performed on the components, and need
10062 -- not be repeated.
10066 then
10070 -- If we are out of range, post error. This is one of the
10071 -- very few places that we place the flag in the middle of
10072 -- a token, right under the offending wide character.
10074 -- This is not quite right, because characters in general
10075 -- will take more than one character position ???
10077 Error_Msg
10084 -- If the root type is not a standard character, then we will convert
10085 -- the string into an aggregate and will let the aggregate code do
10086 -- the checking. Standard Wide_Wide_Character is also OK here.
10088 else
10092 -- See if the component type of the array corresponding to the string
10093 -- has compile time known bounds. If yes we can directly check
10094 -- whether the evaluation of the string will raise constraint error.
10095 -- Otherwise we need to transform the string literal into the
10096 -- corresponding character aggregate and let the aggregate code do
10097 -- the checking.
10101 -- Check for the case of full range, where we are definitely OK
10107 -- Here the range is not the complete base type range, so check
10109 declare
10117 begin
10120 then
10126 then
10127 Apply_Compile_Time_Constraint_Error
10129 CE_Range_Check_Failed,
10140 -- If we got here we meed to transform the string literal into the
10141 -- equivalent qualified positional array aggregate. This is rather
10142 -- heavy artillery for this situation, but it is hard work to avoid.
10144 declare
10149 begin
10150 -- Build the character literals, we give them source locations that
10151 -- correspond to the string positions, which is a bit tricky given
10152 -- the possible presence of wide character escape sequences.
10166 -- Should we have a call to Skip_Wide here ???
10168 -- ??? else
10169 -- Skip_Wide (P);
10177 Expression =>
10184 -----------------------------
10185 -- Resolve_Type_Conversion --
10186 -----------------------------
10198 -- Set to False to suppress cases where we want to suppress the test
10199 -- for redundancy to avoid possible false positives on this warning.
10201 begin
10202 if not Conv_OK
10204 then
10208 -- If the Operand Etype is Universal_Fixed, then the conversion is
10209 -- never redundant. We need this check because by the time we have
10210 -- finished the rather complex transformation, the conversion looks
10211 -- redundant when it is not.
10216 -- If the operand is marked as Any_Fixed, then special processing is
10217 -- required. This is also a case where we suppress the test for a
10218 -- redundant conversion, since most certainly it is not redundant.
10223 -- Mixed-mode operation involving a literal. Context must be a fixed
10224 -- type which is applied to the literal subsequently.
10232 or else
10234 then
10235 -- Return if expression is ambiguous
10240 -- If nothing else, the available fixed type is Duration
10242 else
10246 -- Resolve the real operand with largest available precision
10250 else
10256 -- If the operand is a literal (it could be a non-static and
10257 -- illegal exponentiation) check whether the use of Duration
10258 -- is potentially inaccurate.
10263 then
10264 Error_Msg_N
10267 Error_Msg_N
10274 then
10277 else
10286 -- In SPARK, a type conversion between array types should be restricted
10287 -- to types which have matching static bounds.
10289 -- Protect call to Matching_Static_Array_Bounds to avoid costly
10290 -- operation if not needed.
10297 then
10298 Check_SPARK_05_Restriction
10302 -- In formal mode, the operand of an ancestor type conversion must be an
10303 -- object (not an expression).
10311 then
10317 -- Note: we do the Eval_Type_Conversion call before applying the
10318 -- required checks for a subtype conversion. This is important, since
10319 -- both are prepared under certain circumstances to change the type
10320 -- conversion to a constraint error node, but in the case of
10321 -- Eval_Type_Conversion this may reflect an illegality in the static
10322 -- case, and we would miss the illegality (getting only a warning
10323 -- message), if we applied the type conversion checks first.
10327 -- Even when evaluation is not possible, we may be able to simplify the
10328 -- conversion or its expression. This needs to be done before applying
10329 -- checks, since otherwise the checks may use the original expression
10330 -- and defeat the simplifications. This is specifically the case for
10331 -- elimination of the floating-point Truncation attribute in
10332 -- float-to-int conversions.
10336 -- If after evaluation we still have a type conversion, then we may need
10337 -- to apply checks required for a subtype conversion.
10339 -- Skip these type conversion checks if universal fixed operands
10340 -- operands involved, since range checks are handled separately for
10341 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
10347 then
10351 -- Issue warning for conversion of simple object to its own type. We
10352 -- have to test the original nodes, since they may have been rewritten
10353 -- by various optimizations.
10357 -- Here we test for a redundant conversion if the warning mode is
10358 -- active (and was not locally reset), and we have a type conversion
10359 -- from source not appearing in a generic instance.
10361 if Test_Redundant
10364 and then not In_Instance
10365 then
10369 -- If the node is part of a larger expression, the Target_Type
10370 -- may not be the original type of the node if the context is a
10371 -- condition. Recover original type to see if conversion is needed.
10375 then
10379 -- If we have an entity name, then give the warning if the entity
10380 -- is the right type, or if it is a loop parameter covered by the
10381 -- original type (that's needed because loop parameters have an
10382 -- odd subtype coming from the bounds).
10385 and then
10387 or else
10391 -- If not an entity, then type of expression must match
10394 then
10395 -- One more check, do not give warning if the analyzed conversion
10396 -- has an expression with non-static bounds, and the bounds of the
10397 -- target are static. This avoids junk warnings in cases where the
10398 -- conversion is necessary to establish staticness, for example in
10399 -- a case statement.
10403 then
10406 -- Finally, if this type conversion occurs in a context requiring
10407 -- a prefix, and the expression is a qualified expression then the
10408 -- type conversion is not redundant, since a qualified expression
10409 -- is not a prefix, whereas a type conversion is. For example, "X
10410 -- := T'(Funx(...)).Y;" is illegal because a selected component
10411 -- requires a prefix, but a type conversion makes it legal: "X :=
10412 -- T(T'(Funx(...))).Y;"
10414 -- In Ada 2012, a qualified expression is a name, so this idiom is
10415 -- no longer needed, but we still suppress the warning because it
10416 -- seems unfriendly for warnings to pop up when you switch to the
10417 -- newer language version.
10421 N_Indexed_Component,
10422 N_Selected_Component,
10423 N_Slice,
10424 N_Explicit_Dereference)
10425 then
10428 -- Never warn on conversion to Long_Long_Integer'Base since
10429 -- that is most likely an artifact of the extended overflow
10430 -- checking and comes from complex expanded code.
10435 -- Here we give the redundant conversion warning. If it is an
10436 -- entity, give the name of the entity in the message. If not,
10437 -- just mention the expression.
10439 -- Shoudn't we test Warn_On_Redundant_Constructs here ???
10441 else
10444 Error_Msg_NE -- CODEFIX
10447 else
10448 Error_Msg_NE
10456 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
10457 -- No need to perform any interface conversion if the type of the
10458 -- expression coincides with the target type.
10461 and then Expander_Active
10463 then
10464 declare
10468 begin
10469 -- If the type of the operand is a limited view, use the non-
10470 -- limited view when available.
10475 then
10491 -- Conversion from interface type
10495 -- Ada 2005 (AI-217): Handle entities from limited views
10499 Error_Msg_NE -- CODEFIX
10502 Error_Msg_N
10504 N);
10507 and then not
10510 then
10512 Error_Msg_NE -- CODEFIX
10515 Error_Msg_N
10517 N);
10519 else
10523 -- Conversion to interface type
10527 -- Handle subtypes
10534 or else Interface_Present_In_Ancestor
10537 then
10539 else
10542 Error_Msg_N
10550 -- Ada 2012: if target type has predicates, the result requires a
10551 -- predicate check. If the context is a call to another predicate
10552 -- check we must prevent infinite recursion.
10558 or else
10560 then
10563 else
10568 -- If at this stage we have a real to integer conversion, make sure
10569 -- that the Do_Range_Check flag is set, because such conversions in
10570 -- general need a range check. We only need this if expansion is off
10571 -- or we are in GNATProve mode.
10577 then
10582 ----------------------
10583 -- Resolve_Unary_Op --
10584 ----------------------
10593 begin
10596 Check_SPARK_05_Restriction
10600 -- Deal with intrinsic unary operators
10606 then
10611 -- Deal with universal cases
10614 or else
10616 then
10623 -- Generate warning for expressions like abs (x mod 2)
10625 if Warn_On_Redundant_Constructs
10627 then
10631 Error_Msg_N -- CODEFIX
10636 -- Deal with reference generation
10643 -- Set overflow checking bit. Much cleverer code needed here eventually
10644 -- and perhaps the Resolve routines should be separated for the various
10645 -- arithmetic operations, since they will need different processing ???
10653 -- Generate warning for expressions like -5 mod 3 for integers. No need
10654 -- to worry in the floating-point case, since parens do not affect the
10655 -- result so there is no point in giving in a warning.
10657 declare
10666 begin
10667 if Warn_On_Questionable_Missing_Parens
10671 then
10674 -- We are looking for cases where the right operand is not
10675 -- parenthesized, and is a binary operator, multiply, divide, or
10676 -- mod. These are the cases where the grouping can affect results.
10680 then
10681 -- For mod, we always give the warning, since the value is
10682 -- affected by the parenthesization (e.g. (-5) mod 315 /=
10683 -- -(5 mod 315)). But for the other cases, the only concern is
10684 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
10685 -- overflows, but (-2) * 64 does not). So we try to give the
10686 -- message only when overflow is possible.
10690 then
10695 else
10701 else
10705 -- Note that the test below is deliberately excluding the
10706 -- largest negative number, since that is a potentially
10707 -- troublesome case (e.g. -2 * x, where the result is the
10708 -- largest negative integer has an overflow with 2 * x).
10715 -- For the multiplication case, the only case we have to worry
10716 -- about is when (-a)*b is exactly the largest negative number
10717 -- so that -(a*b) can cause overflow. This can only happen if
10718 -- a is a power of 2, and more generally if any operand is a
10719 -- constant that is not a power of 2, then the parentheses
10720 -- cannot affect whether overflow occurs. We only bother to
10721 -- test the left most operand
10723 -- Loop looking at left operands for one that has known value
10730 -- Operand value of 0 or 1 skips warning
10735 -- Otherwise check power of 2, if power of 2, warn, if
10736 -- anything else, skip warning.
10738 else
10742 else
10751 -- Keep looking at left operands
10756 -- For rem or "/" we can only have a problematic situation
10757 -- if the divisor has a value of minus one or one. Otherwise
10758 -- overflow is impossible (divisor > 1) or we have a case of
10759 -- division by zero in any case.
10764 then
10768 -- If we fall through warning should be issued
10770 -- Shouldn't we test Warn_On_Questionable_Missing_Parens ???
10772 Error_Msg_N
10779 ----------------------------------
10780 -- Resolve_Unchecked_Expression --
10781 ----------------------------------
10783 procedure Resolve_Unchecked_Expression
10786 is
10787 begin
10792 ---------------------------------------
10793 -- Resolve_Unchecked_Type_Conversion --
10794 ---------------------------------------
10796 procedure Resolve_Unchecked_Type_Conversion
10799 is
10805 begin
10806 -- Resolve operand using its own type
10810 -- In an inlined context, the unchecked conversion may be applied
10811 -- to a literal, in which case its type is the type of the context.
10812 -- (In other contexts conversions cannot apply to literals).
10814 if In_Inlined_Body
10818 then
10826 ------------------------------
10827 -- Rewrite_Operator_As_Call --
10828 ------------------------------
10835 begin
10842 New_N :=
10853 ------------------------------
10854 -- Rewrite_Renamed_Operator --
10855 ------------------------------
10857 procedure Rewrite_Renamed_Operator
10861 is
10866 begin
10867 -- Do not perform this transformation within a pre/postcondition,
10868 -- because the expression will be re-analyzed, and the transformation
10869 -- might affect the visibility of the operator, e.g. in an instance.
10875 -- Rewrite the operator node using the real operator, not its renaming.
10876 -- Exclude user-defined intrinsic operations of the same name, which are
10877 -- treated separately and rewritten as calls.
10886 -- Indicate that both the original entity and its renaming are
10887 -- referenced at this point.
10898 -- If the context type is private, add the appropriate conversions so
10899 -- that the operator is applied to the full view. This is done in the
10900 -- routines that resolve intrinsic operators.
10904 then
10906 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
10907 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
10920 -- Operator renames a user-defined operator of the same name. Use the
10921 -- original operator in the node, which is the one Gigi knows about.
10928 -----------------------
10929 -- Set_Slice_Subtype --
10930 -----------------------
10932 -- Build an implicit subtype declaration to represent the type delivered by
10933 -- the slice. This is an abbreviated version of an array subtype. We define
10934 -- an index subtype for the slice, using either the subtype name or the
10935 -- discrete range of the slice. To be consistent with index usage elsewhere
10936 -- we create a list header to hold the single index. This list is not
10937 -- otherwise attached to the syntax tree.
10948 begin
10954 else
10955 -- We force the evaluation of a range. This is definitely needed in
10956 -- the renamed case, and seems safer to do unconditionally. Note in
10957 -- any case that since we will create and insert an Itype referring
10958 -- to this range, we must make sure any side effect removal actions
10959 -- are inserted before the Itype definition.
10965 -- If the discrete range is given by a subtype indication, the
10966 -- type of the slice is the base of the subtype mark.
10969 declare
10971 begin
10980 -- Take a new copy of Drange (where bounds have been rewritten to
10981 -- reference side-effect-free names). Using a separate tree ensures
10982 -- that further expansion (e.g. while rewriting a slice assignment
10983 -- into a FOR loop) does not attempt to remove side effects on the
10984 -- bounds again (which would cause the bounds in the index subtype
10985 -- definition to refer to temporaries before they are defined) (the
10986 -- reason is that some names are considered side effect free here
10987 -- for the subtype, but not in the context of a loop iteration
10988 -- scheme).
11009 -- The Etype of the existing Slice node is reset to this slice subtype.
11010 -- Its bounds are obtained from its first index.
11014 -- For packed slice subtypes, freeze immediately (except in the case of
11015 -- being in a "spec expression" where we never freeze when we first see
11016 -- the expression).
11021 -- For all other cases insert an itype reference in the slice's actions
11022 -- so that the itype is frozen at the proper place in the tree (i.e. at
11023 -- the point where actions for the slice are analyzed). Note that this
11024 -- is different from freezing the itype immediately, which might be
11025 -- premature (e.g. if the slice is within a transient scope). This needs
11026 -- to be done only if expansion is enabled.
11033 --------------------------------
11034 -- Set_String_Literal_Subtype --
11035 --------------------------------
11043 begin
11055 -- The low bound is set from the low bound of the corresponding index
11056 -- type. Note that we do not store the high bound in the string literal
11057 -- subtype, but it can be deduced if necessary from the length and the
11058 -- low bound.
11063 -- If the lower bound is not static we create a range for the string
11064 -- literal, using the index type and the known length of the literal.
11065 -- The index type is not necessarily Positive, so the upper bound is
11066 -- computed as T'Val (T'Pos (Low_Bound) + L - 1).
11068 else
11069 declare
11075 Prefix =>
11079 Left_Opnd =>
11082 Prefix =>
11084 Expressions =>
11086 Right_Opnd =>
11095 begin
11097 Set_String_Literal_Low_Bound
11100 else
11101 -- If the index type is an enumeration type, build bounds
11102 -- expression with attributes.
11104 Set_String_Literal_Low_Bound
11108 Prefix =>
11115 -- Build bona fide subtype for the string, and wrap it in an
11116 -- unchecked conversion, because the backend expects the
11117 -- String_Literal_Subtype to have a static lower bound.
11119 Index_Subtype :=
11126 -- In the context, the Index_Type may already have a constraint,
11127 -- so use common base type on string subtype. The base type may
11128 -- be used when generating attributes of the string, for example
11129 -- in the context of a slice assignment.
11154 ------------------------------
11155 -- Simplify_Type_Conversion --
11156 ------------------------------
11159 begin
11161 declare
11166 begin
11167 -- Special processing if the conversion is the expression of a
11168 -- Rounding or Truncation attribute reference. In this case we
11169 -- replace:
11171 -- ityp (ftyp'Rounding (x)) or ityp (ftyp'Truncation (x))
11173 -- by
11175 -- ityp (x)
11177 -- with the Float_Truncate flag set to False or True respectively,
11178 -- which is more efficient.
11181 and then
11187 Name_Truncation)
11188 then
11189 declare
11192 begin
11202 -----------------------------
11203 -- Unique_Fixed_Point_Type --
11204 -----------------------------
11213 -- Give error messages for true ambiguity. Messages are posted on node
11214 -- N, and entities T1, T2 are the possible interpretations.
11216 -----------------------
11217 -- Fixed_Point_Error --
11218 -----------------------
11221 begin
11227 -- Start of processing for Unique_Fixed_Point_Type
11229 begin
11230 -- The operations on Duration are visible, so Duration is always a
11231 -- possible interpretation.
11235 -- Look for fixed-point types in enclosing scopes
11244 then
11246 Fixed_Point_Error;
11248 else
11259 -- Look for visible fixed type declarations in the context
11270 then
11272 Fixed_Point_Error;
11274 else
11287 Error_Msg_NE
11289 else
11290 Error_Msg_NE
11297 ----------------------
11298 -- Valid_Conversion --
11299 ----------------------
11301 function Valid_Conversion
11306 is
11311 function Conversion_Check
11314 -- Little routine to post Msg if Valid is False, returns Valid value
11317 -- If Report_Errs, then calls Errout.Error_Msg_N with its arguments
11319 procedure Conversion_Error_NE
11323 -- If Report_Errs, then calls Errout.Error_Msg_NE with its arguments
11325 function Valid_Tagged_Conversion
11328 -- Specifically test for validity of tagged conversions
11331 -- Check index and component conformance, and accessibility levels if
11332 -- the component types are anonymous access types (Ada 2005).
11334 ----------------------
11335 -- Conversion_Check --
11336 ----------------------
11338 function Conversion_Check
11341 is
11342 begin
11343 if not Valid
11345 -- A generic unit has already been analyzed and we have verified
11346 -- that a particular conversion is OK in that context. Since the
11347 -- instance is reanalyzed without relying on the relationships
11348 -- established during the analysis of the generic, it is possible
11349 -- to end up with inconsistent views of private types. Do not emit
11350 -- the error message in such cases. The rest of the machinery in
11351 -- Valid_Conversion still ensures the proper compatibility of
11352 -- target and operand types.
11354 and then not In_Instance
11355 then
11362 ------------------------
11363 -- Conversion_Error_N --
11364 ------------------------
11367 begin
11373 -------------------------
11374 -- Conversion_Error_NE --
11375 -------------------------
11377 procedure Conversion_Error_NE
11381 is
11382 begin
11388 ----------------------------
11389 -- Valid_Array_Conversion --
11390 ----------------------------
11393 is
11408 begin
11409 -- Error if wrong number of dimensions
11411 if
11413 then
11414 Conversion_Error_N
11418 -- Number of dimensions matches
11420 else
11421 -- Loop through indexes of the two arrays
11429 -- Error if index types are incompatible
11435 then
11436 Conversion_Error_N
11438 Operand);
11446 -- If component types have same base type, all set
11451 -- Here if base types of components are not the same. The only
11452 -- time this is allowed is if we have anonymous access types.
11454 -- The conversion of arrays of anonymous access types can lead
11455 -- to dangling pointers. AI-392 formalizes the accessibility
11456 -- checks that must be applied to such conversions to prevent
11457 -- out-of-scope references.
11459 elsif Ekind_In
11461 E_Anonymous_Access_Subprogram_Type)
11463 and then
11465 then
11468 then
11471 Conversion_Error_N
11481 -- Conversion not allowed because of accessibility levels
11483 else
11484 Conversion_Error_N
11490 else
11494 -- All other cases where component base types do not match
11496 else
11497 Conversion_Error_N
11499 Operand);
11503 -- Check that component subtypes statically match. For numeric
11504 -- types this means that both must be either constrained or
11505 -- unconstrained. For enumeration types the bounds must match.
11506 -- All of this is checked in Subtypes_Statically_Match.
11508 if not Subtypes_Statically_Match
11510 then
11511 Conversion_Error_N
11520 -----------------------------
11521 -- Valid_Tagged_Conversion --
11522 -----------------------------
11524 function Valid_Tagged_Conversion
11527 is
11528 begin
11529 -- Upward conversions are allowed (RM 4.6(22))
11533 then
11536 -- Downward conversion are allowed if the operand is class-wide
11537 -- (RM 4.6(23)).
11541 then
11546 then
11547 return
11551 -- Ada 2005 (AI-251): The conversion to/from interface types is
11552 -- always valid
11557 -- If the operand is a class-wide type obtained through a limited_
11558 -- with clause, and the context includes the non-limited view, use
11559 -- it to determine whether the conversion is legal.
11565 then
11570 then
11573 else
11574 Conversion_Error_NE
11581 -- Start of processing for Valid_Conversion
11583 begin
11587 declare
11595 begin
11596 -- Remove procedure calls, which syntactically cannot appear in
11597 -- this context, but which cannot be removed by type checking,
11598 -- because the context does not impose a type.
11600 -- The node may be labelled overloaded, but still contain only one
11601 -- interpretation because others were discarded earlier. If this
11602 -- is the case, retain the single interpretation if legal.
11610 then
11611 -- More than one candidate interpretation is available
11619 -- When compiling for a system where Address is of a visible
11620 -- integer type, spurious ambiguities can be produced when
11621 -- arithmetic operations have a literal operand and return
11622 -- System.Address or a descendant of it. These ambiguities
11623 -- are usually resolved by the context, but for conversions
11624 -- there is no context type and the removal of the spurious
11625 -- operations must be done explicitly here.
11627 if not Address_Is_Private
11629 then
11654 Conversion_Error_N
11657 -- If the interpretation involves a standard operator, use
11658 -- the location of the type, which may be user-defined.
11662 else
11666 Conversion_Error_N -- CODEFIX
11671 else
11675 Conversion_Error_N -- CODEFIX
11687 -- Deal with conversion of integer type to address if the pragma
11688 -- Allow_Integer_Address is in effect. We convert the conversion to
11689 -- an unchecked conversion in this case and we are all done.
11697 -- If we are within a child unit, check whether the type of the
11698 -- expression has an ancestor in a parent unit, in which case it
11699 -- belongs to its derivation class even if the ancestor is private.
11700 -- See RM 7.3.1 (5.2/3).
11704 -- Numeric types
11708 -- A universal fixed expression can be converted to any numeric type
11713 -- Also no need to check when in an instance or inlined body, because
11714 -- the legality has been established when the template was analyzed.
11715 -- Furthermore, numeric conversions may occur where only a private
11716 -- view of the operand type is visible at the instantiation point.
11717 -- This results in a spurious error if we check that the operand type
11718 -- is a numeric type.
11720 -- Note: in a previous version of this unit, the following tests were
11721 -- applied only for generated code (Comes_From_Source set to False),
11722 -- but in fact the test is required for source code as well, since
11723 -- this situation can arise in source code.
11728 -- Otherwise we need the conversion check
11730 else
11731 return Conversion_Check
11733 or else
11739 -- Array types
11745 then
11746 Conversion_Error_N
11750 else
11754 -- Ada 2005 (AI-251): Anonymous access types where target references an
11755 -- interface type.
11758 E_Anonymous_Access_Type)
11760 then
11761 -- Check the static accessibility rule of 4.6(17). Note that the
11762 -- check is not enforced when within an instance body, since the
11763 -- RM requires such cases to be caught at run time.
11765 -- If the operand is a rewriting of an allocator no check is needed
11766 -- because there are no accessibility issues.
11774 then
11775 -- In an instance, this is a run-time check, but one we know
11776 -- will fail, so generate an appropriate warning. The raise
11777 -- will be generated by Expand_N_Type_Conversion.
11781 Conversion_Error_N
11783 Operand);
11786 else
11787 Conversion_Error_N
11789 Operand);
11793 -- Special accessibility checks are needed in the case of access
11794 -- discriminants declared for a limited type.
11798 then
11799 -- When the operand is a selected access discriminant the check
11800 -- needs to be made against the level of the object denoted by
11801 -- the prefix of the selected name (Object_Access_Level handles
11802 -- checking the prefix of the operand for this case).
11807 then
11808 -- In an instance, this is a run-time check, but one we know
11809 -- will fail, so generate an appropriate warning. The raise
11810 -- will be generated by Expand_N_Type_Conversion.
11814 Conversion_Error_N
11819 -- Real error if not in instance body
11821 else
11822 Conversion_Error_N
11829 -- The case of a reference to an access discriminant from
11830 -- within a limited type declaration (which will appear as
11831 -- a discriminal) is always illegal because the level of the
11832 -- discriminant is considered to be deeper than any (nameable)
11833 -- access type.
11837 and then
11840 then
11841 Conversion_Error_N
11843 Operand);
11851 -- General and anonymous access types
11854 E_Anonymous_Access_Type)
11855 and then
11856 Conversion_Check
11858 and then not
11860 E_Access_Protected_Subprogram_Type),
11862 then
11865 then
11866 Conversion_Error_N
11871 -- Check the static accessibility rule of 4.6(17). Note that the
11872 -- check is not enforced when within an instance body, since the RM
11873 -- requires such cases to be caught at run time.
11878 N_Object_Declaration
11879 then
11880 -- Ada 2012 (AI05-0149): Perform legality checking on implicit
11881 -- conversions from an anonymous access type to a named general
11882 -- access type. Such conversions are not allowed in the case of
11883 -- access parameters and stand-alone objects of an anonymous
11884 -- access type. The implicit conversion case is recognized by
11885 -- testing that Comes_From_Source is False and that it's been
11886 -- rewritten. The Comes_From_Source test isn't sufficient because
11887 -- nodes in inlined calls to predefined library routines can have
11888 -- Comes_From_Source set to False. (Is there a better way to test
11889 -- for implicit conversions???)
11896 then
11899 -- Implicit conversions aren't allowed for objects of an
11900 -- anonymous access type, since such objects have nonstatic
11901 -- levels in Ada 2012.
11904 N_Object_Declaration
11905 then
11906 Conversion_Error_N
11911 -- Implicit conversions aren't allowed for anonymous access
11912 -- parameters. The "not Is_Local_Anonymous_Access_Type" test
11913 -- is done to exclude anonymous access results.
11917 N_Function_Specification,
11918 N_Procedure_Specification)
11919 then
11920 Conversion_Error_N
11925 -- This is a case where there's an enclosing object whose
11926 -- to which the "statically deeper than" relationship does
11927 -- not apply (such as an access discriminant selected from
11928 -- a dereference of an access parameter).
11932 then
11933 Conversion_Error_N
11938 -- In other cases, the level of the operand's type must be
11939 -- statically less deep than that of the target type, else
11940 -- implicit conversion is disallowed (by RM12-8.6(27.1/3)).
11944 then
11945 Conversion_Error_N
11954 then
11955 -- In an instance, this is a run-time check, but one we know
11956 -- will fail, so generate an appropriate warning. The raise
11957 -- will be generated by Expand_N_Type_Conversion.
11961 Conversion_Error_N
11963 Operand);
11966 -- If not in an instance body, this is a real error
11968 else
11969 -- Avoid generation of spurious error message
11972 Conversion_Error_N
11974 Operand);
11980 -- Special accessibility checks are needed in the case of access
11981 -- discriminants declared for a limited type.
11985 then
11986 -- When the operand is a selected access discriminant the check
11987 -- needs to be made against the level of the object denoted by
11988 -- the prefix of the selected name (Object_Access_Level handles
11989 -- checking the prefix of the operand for this case).
11994 then
11995 -- In an instance, this is a run-time check, but one we know
11996 -- will fail, so generate an appropriate warning. The raise
11997 -- will be generated by Expand_N_Type_Conversion.
12001 Conversion_Error_N
12006 -- If not in an instance body, this is a real error
12008 else
12009 Conversion_Error_N
12016 -- The case of a reference to an access discriminant from
12017 -- within a limited type declaration (which will appear as
12018 -- a discriminal) is always illegal because the level of the
12019 -- discriminant is considered to be deeper than any (nameable)
12020 -- access type.
12023 and then
12026 then
12027 Conversion_Error_N
12029 Operand);
12035 -- In the presence of limited_with clauses we have to use non-limited
12036 -- views, if available.
12040 -- Helper function to handle limited views
12042 --------------------------
12043 -- Full_Designated_Type --
12044 --------------------------
12049 begin
12050 -- Handle the limited view of a type
12055 then
12057 else
12062 -- Local Declarations
12070 -- Start of processing for Check_Limited
12072 begin
12076 else
12078 Conversion_Error_NE
12083 -- Ada 2005 AI-384: legality rule is symmetric in both
12084 -- designated types. The conversion is legal (with possible
12085 -- constraint check) if either designated type is
12086 -- unconstrained.
12089 or else
12091 and then
12094 then
12095 -- Special case, if Value_Size has been used to make the
12096 -- sizes different, the conversion is not allowed even
12097 -- though the subtypes statically match.
12102 then
12103 Conversion_Error_NE
12106 Conversion_Error_NE
12111 -- Normal case where conversion is allowed
12113 else
12117 else
12118 Error_Msg_NE
12126 -- Access to subprogram types. If the operand is an access parameter,
12127 -- the type has a deeper accessibility that any master, and cannot be
12128 -- assigned. We must make an exception if the conversion is part of an
12129 -- assignment and the target is the return object of an extended return
12130 -- statement, because in that case the accessibility check takes place
12131 -- after the return.
12135 -- Note: this test of Opnd_Type is there to prevent entering this
12136 -- branch in the case of a remote access to subprogram type, which
12137 -- is internally represented as an E_Record_Type.
12140 then
12144 and then
12148 then
12149 Conversion_Error_N
12151 Operand);
12152 Conversion_Error_N
12155 Operand);
12157 Error_Msg_NE
12162 -- Check that the designated types are subtype conformant
12168 -- Check the static accessibility rule of 4.6(20)
12172 then
12173 Conversion_Error_N
12175 Operand);
12177 -- Check that if the operand type is declared in a generic body,
12178 -- then the target type must be declared within that same body
12179 -- (enforces last sentence of 4.6(20)).
12182 declare
12188 begin
12195 Conversion_Error_N
12204 -- Remote access to subprogram types
12208 then
12209 -- It is valid to convert from one RAS type to another provided
12210 -- that their specification statically match.
12212 -- Note: at this point, remote access to subprogram types have been
12213 -- expanded to their E_Record_Type representation, and we need to
12214 -- go back to the original access type definition using the
12215 -- Corresponding_Remote_Type attribute in order to check that the
12216 -- designated profiles match.
12221 Check_Subtype_Conformant
12224 Old_Id =>
12226 Err_Loc =>
12227 N);
12230 -- If it was legal in the generic, it's legal in the instance
12235 -- If both are tagged types, check legality of view conversions
12238 and then
12240 then
12243 -- Types derived from the same root type are convertible
12248 -- In an instance or an inlined body, there may be inconsistent views of
12249 -- the same type, or of types derived from a common root.
12252 and then
12255 then
12258 -- Special check for common access type error case
12262 then
12264 Conversion_Error_NE -- CODEFIX
12268 -- Here we have a real conversion error
12270 else
12271 Conversion_Error_NE