| blob | 3d6c39583c84886567680e0cbbb80cca51825116 |
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S E M _ R E S --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2016, 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 ------------------------------------------------------------------------------
87 -----------------------
88 -- Local Subprograms --
89 -----------------------
91 -- Second pass (top-down) type checking and overload resolution procedures
92 -- Typ is the type required by context. These procedures propagate the
93 -- type information recursively to the descendants of N. If the node is not
94 -- overloaded, its Etype is established in the first pass. If overloaded,
95 -- the Resolve routines set the correct type. For arithmetic operators, the
96 -- Etype is the base type of the context.
98 -- Note that Resolve_Attribute is separated off in Sem_Attr
101 -- Enforce the restrictions on the use of discriminants when constraining
102 -- a component of a discriminated type (record or concurrent type).
105 -- Given a node for an operator associated with type T, check that the
106 -- operator is visible. Operators all of whose operands are universal must
107 -- be checked for visibility during resolution because their type is not
108 -- determinable based on their operands.
110 procedure Check_Fully_Declared_Prefix
113 -- Check that the type of the prefix of a dereference is not incomplete
116 -- Given a call node, N, which is known to occur immediately within the
117 -- subprogram being called, determines whether it is a detectable case of
118 -- an infinite recursion, and if so, outputs appropriate messages. Returns
119 -- True if an infinite recursion is detected, and False otherwise.
122 -- If the type of the object being initialized uses the secondary stack
123 -- directly or indirectly, create a transient scope for the call to the
124 -- init proc. This is because we do not create transient scopes for the
125 -- initialization of individual components within the init proc itself.
126 -- Could be optimized away perhaps?
129 -- N is the node for a logical operator. If the operator is predefined, and
130 -- the root type of the operands is Standard.Boolean, then a check is made
131 -- for restriction No_Direct_Boolean_Operators. This procedure also handles
132 -- the style check for Style_Check_Boolean_And_Or.
135 -- N is either an indexed component or a selected component. This function
136 -- returns true if the prefix refers to an object that has an address
137 -- clause (the case in which we may want to issue a warning).
140 -- Determine whether E is an access type declared by an access declaration,
141 -- and not an (anonymous) allocator type.
144 -- Utility to check whether the entity for an operator is a predefined
145 -- operator, in which case the expression is left as an operator in the
146 -- tree (else it is rewritten into a call). An instance of an intrinsic
147 -- conversion operation may be given an operator name, but is not treated
148 -- like an operator. Note that an operator that is an imported back-end
149 -- builtin has convention Intrinsic, but is expected to be rewritten into
150 -- a call, so such an operator is not treated as predefined by this
151 -- predicate.
154 -- If a default expression in entry call N depends on the discriminants
155 -- of the task, it must be replaced with a reference to the discriminant
156 -- of the task being called.
158 procedure Resolve_Op_Concat_Arg
163 -- Internal procedure for Resolve_Op_Concat to resolve one operand of
164 -- concatenation operator. The operand is either of the array type or of
165 -- the component type. If the operand is an aggregate, and the component
166 -- type is composite, this is ambiguous if component type has aggregates.
169 -- Does the first part of the work of Resolve_Op_Concat
172 -- Does the "rest" of the work of Resolve_Op_Concat, after the left operand
173 -- has been resolved. See Resolve_Op_Concat for details.
212 function Operator_Kind
215 -- Utility to map the name of an operator into the corresponding Node. Used
216 -- by other node rewriting procedures.
219 -- Resolve actuals of call, and add default expressions for missing ones.
220 -- N is the Node_Id for the subprogram call, and Nam is the entity of the
221 -- called subprogram.
224 -- Called from Resolve_Call, when the prefix denotes an entry or element
225 -- of entry family. Actuals are resolved as for subprograms, and the node
226 -- is rebuilt as an entry call. Also called for protected operations. Typ
227 -- is the context type, which is used when the operation is a protected
228 -- function with no arguments, and the return value is indexed.
231 -- A call to a user-defined intrinsic operator is rewritten as a call to
232 -- the corresponding predefined operator, with suitable conversions. Note
233 -- that this applies only for intrinsic operators that denote predefined
234 -- operators, not ones that are intrinsic imports of back-end builtins.
237 -- Ditto, for arithmetic unary operators
240 -- If an operator node resolves to a call to a user-defined operator,
241 -- rewrite the node as a function call.
243 procedure Make_Call_Into_Operator
247 -- Inverse transformation: if an operator is given in functional notation,
248 -- then after resolving the node, transform into an operator node, so that
249 -- operands are resolved properly. Recall that predefined operators do not
250 -- have a full signature and special resolution rules apply.
252 procedure Rewrite_Renamed_Operator
256 -- An operator can rename another, e.g. in an instantiation. In that
257 -- case, the proper operator node must be constructed and resolved.
260 -- The String_Literal_Subtype is built for all strings that are not
261 -- operands of a static concatenation operation. If the argument is not
262 -- a N_String_Literal node, then the call has no effect.
265 -- Build subtype of array type, with the range specified by the slice
268 -- Called after N has been resolved and evaluated, but before range checks
269 -- have been applied. Currently simplifies a combination of floating-point
270 -- to integer conversion and Rounding or Truncation attribute.
273 -- A universal_fixed expression in an universal context is unambiguous if
274 -- there is only one applicable fixed point type. Determining whether there
275 -- is only one requires a search over all visible entities, and happens
276 -- only in very pathological cases (see 6115-006).
278 -------------------------
279 -- Ambiguous_Character --
280 -------------------------
285 begin
289 -- First the ones in Standard
294 -- Include Wide_Wide_Character in Ada 2005 mode
300 -- Now any other types that match
310 -------------------------
311 -- Analyze_And_Resolve --
312 -------------------------
315 begin
321 begin
326 -- Versions with check(s) suppressed
328 procedure Analyze_And_Resolve
332 is
335 begin
337 declare
339 begin
345 else
346 declare
348 begin
356 and then Scope_Is_Transient
357 then
358 -- This can only happen if a transient scope was created for an inner
359 -- expression, which will be removed upon completion of the analysis
360 -- of an enclosing construct. The transient scope must have the
361 -- suppress status of the enclosing environment, not of this Analyze
362 -- call.
365 Scope_Suppress;
369 procedure Analyze_And_Resolve
372 is
375 begin
377 declare
379 begin
385 else
386 declare
388 begin
397 Scope_Suppress;
401 ----------------------------
402 -- Check_Discriminant_Use --
403 ----------------------------
411 begin
412 -- Any use in a spec-expression is legal
419 -- Discriminant cannot be used to constrain a scalar type
426 then
431 -- The following check catches the unusual case where a
432 -- discriminant appears within an index constraint that is part
433 -- of a larger expression within a constraint on a component,
434 -- e.g. "C : Int range 1 .. F (new A(1 .. D))". For now we only
435 -- check case of record components, and note that a similar check
436 -- should also apply in the case of discriminant constraints
437 -- below. ???
439 -- Note that the check for N_Subtype_Declaration below is to
440 -- detect the valid use of discriminants in the constraints of a
441 -- subtype declaration when this subtype declaration appears
442 -- inside the scope of a record type (which is syntactically
443 -- illegal, but which may be created as part of derived type
444 -- processing for records). See Sem_Ch3.Build_Derived_Record_Type
445 -- for more info.
449 and then not
451 and then
453 N_Subtype_Declaration)
455 then
456 Error_Msg_N
461 -- Detect a common error:
463 -- type R (D : Positive := 100) is record
464 -- Name : String (1 .. D);
465 -- end record;
467 -- The default value causes an object of type R to be allocated
468 -- with room for Positive'Last characters. The RM does not mandate
469 -- the allocation of the maximum size, but that is what GNAT does
470 -- so we should warn the programmer that there is a problem.
479 -- Return True if type T has a large enough range that any
480 -- array whose index type covered the whole range of the type
481 -- would likely raise Storage_Error.
483 ------------------------
484 -- Large_Storage_Type --
485 ------------------------
488 begin
489 -- The type is considered large if its bounds are known at
490 -- compile time and if it requires at least as many bits as
491 -- a Positive to store the possible values.
495 and then
500 -- Start of processing for Check_Large
502 begin
503 -- Check that the Disc has a large range
509 -- If the enclosing type is limited, we allocate only the
510 -- default value, not the maximum, and there is no need for
511 -- a warning.
517 -- Check that it is the high bound
521 then
525 -- Check the array allows a large range at this bound. First
526 -- find the array
540 -- Next, find the dimension
548 loop
557 -- Now, check the dimension has a large range
563 -- Warn about the danger
565 Error_Msg_N
575 -- Legal case is in index or discriminant constraint
578 N_Discriminant_Association)
579 then
581 Error_Msg_N
586 then
587 Error_Msg_N
593 -- Otherwise, context is an expression. It should not be within (i.e. a
594 -- subexpression of) a constraint for a component.
596 else
600 N_Subtype_Indication,
601 N_Entry_Declaration)
602 loop
608 -- If the discriminant is used in an expression that is a bound of a
609 -- scalar type, an Itype is created and the bounds are attached to
610 -- its range, not to the original subtype indication. Such use is of
611 -- course a double fault.
615 N_Derived_Type_Definition)
618 -- The constraint itself may be given by a subtype indication,
619 -- rather than by a more common discrete range.
622 and then
626 then
627 Error_Msg_N
633 --------------------------------
634 -- Check_For_Visible_Operator --
635 --------------------------------
638 begin
640 Error_Msg_NE -- CODEFIX
642 Error_Msg_N -- CODEFIX
647 ----------------------------------
648 -- Check_Fully_Declared_Prefix --
649 ----------------------------------
651 procedure Check_Fully_Declared_Prefix
654 is
655 begin
656 -- Check that the designated type of the prefix of a dereference is
657 -- not an incomplete type. This cannot be done unconditionally, because
658 -- dereferences of private types are legal in default expressions. This
659 -- case is taken care of in Check_Fully_Declared, called below. There
660 -- are also 2005 cases where it is legal for the prefix to be unfrozen.
662 -- This consideration also applies to similar checks for allocators,
663 -- qualified expressions, and type conversions.
665 -- An additional exception concerns other per-object expressions that
666 -- are not directly related to component declarations, in particular
667 -- representation pragmas for tasks. These will be per-object
668 -- expressions if they depend on discriminants or some global entity.
669 -- If the task has access discriminants, the designated type may be
670 -- incomplete at the point the expression is resolved. This resolution
671 -- takes place within the body of the initialization procedure, where
672 -- the discriminant is replaced by its discriminal.
676 then
679 -- Ada 2005 (AI-326): Tagged incomplete types allowed. The wrong usages
680 -- are handled by Analyze_Access_Attribute, Analyze_Assignment,
681 -- Analyze_Object_Renaming, and Freeze_Entity.
687 E_Incomplete_Type
689 then
691 else
696 ------------------------------
697 -- Check_Infinite_Recursion --
698 ------------------------------
705 -- Check whether list of actuals is identical to list of formals of
706 -- called function (which is also the enclosing scope).
708 ------------------------
709 -- Same_Argument_List --
710 ------------------------
717 begin
720 else
738 -- Start of processing for Check_Infinite_Recursion
740 begin
741 -- Special case, if this is a procedure call and is a call to the
742 -- current procedure with the same argument list, then this is for
743 -- sure an infinite recursion and we insert a call to raise SE.
747 and then Same_Argument_List
748 then
749 declare
751 begin
755 then
767 -- If not that special case, search up tree, quitting if we reach a
768 -- construct (e.g. a conditional) that tells us that this is not a
769 -- case for an infinite recursion warning.
772 loop
775 -- If no parent, then we were not inside a subprogram, this can for
776 -- example happen when processing certain pragmas in a spec. Just
777 -- return False in this case.
783 -- Done if we get to subprogram body, this is definitely an infinite
784 -- recursion case if we did not find anything to stop us.
788 -- If appearing in conditional, result is false
791 N_And_Then,
792 N_Case_Expression,
793 N_Case_Statement,
794 N_If_Expression,
795 N_If_Statement)
796 then
801 then
802 -- If the call is the expression of a return statement and the
803 -- actuals are identical to the formals, it's worth a warning.
804 -- However, we skip this if there is an immediately preceding
805 -- raise statement, since the call is never executed.
807 -- Furthermore, this corresponds to a common idiom:
809 -- function F (L : Thing) return Boolean is
810 -- begin
811 -- raise Program_Error;
812 -- return F (L);
813 -- end F;
815 -- for generating a stub function
818 and then Same_Argument_List
819 then
822 -- OK, return statement is in a statement list, look for raise
824 declare
827 begin
828 -- Skip past N_Freeze_Entity nodes generated by expansion
833 loop
837 -- If no raise statement, give warning. We look at the
838 -- original node, because in the case of "raise ... with
839 -- ...", the node has been transformed into a call.
842 and then
850 else
862 -------------------------------
863 -- Check_Initialization_Call --
864 -------------------------------
870 -- Check whether the creation of an object of the type will involve
871 -- use of the secondary stack. If T is a record type, this is true
872 -- if the expression for some component uses the secondary stack, e.g.
873 -- through a call to a function that returns an unconstrained value.
874 -- False if T is controlled, because cleanups occur elsewhere.
876 -------------
877 -- Uses_SS --
878 -------------
885 begin
886 -- Normally we want to use the underlying type, but if it's not set
887 -- then continue with T.
904 then
905 -- The expression for a dynamic component may be rewritten
906 -- as a dereference, so retrieve original node.
910 -- Return True if the expression is a call to a function
911 -- (including an attribute function such as Image, or a
912 -- user-defined operator) with a result that requires a
913 -- transient scope.
920 then
933 else
938 -- Start of processing for Check_Initialization_Call
940 begin
941 -- Establish a transient scope if the type needs it
948 ---------------------------------------
949 -- Check_No_Direct_Boolean_Operators --
950 ---------------------------------------
953 begin
956 then
957 -- Restriction only applies to original source code
964 -- Do style check (but skip if in instance, error is on template)
973 ------------------------------
974 -- Check_Parameterless_Call --
975 ------------------------------
981 -- If the prefix is of an access_to_subprogram type, the node must be
982 -- rewritten as a call. Ditto if the prefix is overloaded and all its
983 -- interpretations are access to subprograms.
985 ---------------------------
986 -- Prefix_Is_Access_Subp --
987 ---------------------------
993 begin
994 -- If the context is an attribute reference that can apply to
995 -- functions, this is never a parameterless call (RM 4.1.4(6)).
999 Name_Code_Address,
1000 Name_Access)
1001 then
1006 return
1009 else
1014 then
1025 -- Start of processing for Check_Parameterless_Call
1027 begin
1028 -- Defend against junk stuff if errors already detected
1035 then
1042 -- If the context expects a value, and the name is a procedure, this is
1043 -- most likely a missing 'Access. Don't try to resolve the parameterless
1044 -- call, error will be caught when the outer call is analyzed.
1049 and then
1051 N_Function_Call,
1052 N_Procedure_Call_Statement)
1053 then
1057 -- Rewrite as call if overloadable entity that is (or could be, in the
1058 -- overloaded case) a function call. If we know for sure that the entity
1059 -- is an enumeration literal, we do not rewrite it.
1061 -- If the entity is the name of an operator, it cannot be a call because
1062 -- operators cannot have default parameters. In this case, this must be
1063 -- a string whose contents coincide with an operator name. Set the kind
1064 -- of the node appropriately.
1072 -- Rewrite as call if it is an explicit dereference of an expression of
1073 -- a subprogram access type, and the subprogram type is not that of a
1074 -- procedure or entry.
1076 or else
1079 -- Rewrite as call if it is a selected component which is a function,
1080 -- this is the case of a call to a protected function (which may be
1081 -- overloaded with other protected operations).
1083 or else
1086 or else
1088 E_Procedure)
1091 -- If one of the above three conditions is met, rewrite as call. Apply
1092 -- the rewriting only once.
1094 then
1097 then
1099 -- This may be a prefixed call that was not fully analyzed, e.g.
1100 -- an actual in an instance.
1105 then
1113 -- The node is the name of the parameterless call. Preserve its
1114 -- descendants, which may be complex expressions.
1118 -- If overloaded, overload set belongs to new copy
1122 -- Change node to parameterless function call (note that the
1123 -- Parameter_Associations associations field is left set to Empty,
1124 -- its normal default value since there are no parameters)
1142 --------------------------------
1143 -- Is_Atomic_Ref_With_Address --
1144 --------------------------------
1149 begin
1153 else
1154 declare
1157 begin
1165 -----------------------------
1166 -- Is_Definite_Access_Type --
1167 -----------------------------
1171 begin
1177 ----------------------
1178 -- Is_Predefined_Op --
1179 ----------------------
1182 begin
1183 -- Predefined operators are intrinsic subprograms
1189 -- A call to a back-end builtin is never a predefined operator
1200 -----------------------------
1201 -- Make_Call_Into_Operator --
1202 -----------------------------
1204 procedure Make_Call_Into_Operator
1208 is
1223 -- If the operand is not universal, and the operator is given by an
1224 -- expanded name, verify that the operand has an interpretation with a
1225 -- type defined in the given scope of the operator.
1228 -- Find a type of the given class in package Pack that contains the
1229 -- operator.
1231 ---------------------------
1232 -- Operand_Type_In_Scope --
1233 ---------------------------
1240 begin
1244 else
1258 ---------------
1259 -- Type_In_P --
1260 ---------------
1266 -- Verify that node is not part of the type declaration for the
1267 -- candidate type, which would otherwise be invisible.
1269 -------------
1270 -- In_Decl --
1271 -------------
1277 begin
1286 else
1289 loop
1292 else
1301 -- Start of processing for Type_In_P
1303 begin
1304 -- If the context type is declared in the prefix package, this is the
1305 -- desired base type.
1310 else
1324 -- Start of processing for Make_Call_Into_Operator
1326 begin
1329 -- Binary operator
1339 -- Unary operator
1341 else
1347 -- If the operator is denoted by an expanded name, and the prefix is
1348 -- not Standard, but the operator is a predefined one whose scope is
1349 -- Standard, then this is an implicit_operator, inserted as an
1350 -- interpretation by the procedure of the same name. This procedure
1351 -- overestimates the presence of implicit operators, because it does
1352 -- not examine the type of the operands. Verify now that the operand
1353 -- type appears in the given scope. If right operand is universal,
1354 -- check the other operand. In the case of concatenation, either
1355 -- argument can be the component type, so check the type of the result.
1356 -- If both arguments are literals, look for a type of the right kind
1357 -- defined in the given scope. This elaborate nonsense is brought to
1358 -- you courtesy of b33302a. The type itself must be frozen, so we must
1359 -- find the type of the proper class in the given scope.
1361 -- A final wrinkle is the multiplication operator for fixed point types,
1362 -- which is defined in Standard only, and not in the scope of the
1363 -- fixed point type itself.
1368 -- If this is a package renaming, get renamed entity, which will be
1369 -- the scope of the operands if operaton is type-correct.
1375 -- If the entity being called is defined in the given package, it is
1376 -- a renaming of a predefined operator, and known to be legal.
1380 then
1383 -- Visibility does not need to be checked in an instance: if the
1384 -- operator was not visible in the generic it has been diagnosed
1385 -- already, else there is an implicit copy of it in the instance.
1393 then
1398 -- Ada 2005 AI-420: Predefined equality on Universal_Access is
1399 -- available.
1404 then
1407 else
1416 and then Is_Binary
1418 then
1424 -- Verify that the scope contains a type that corresponds to
1425 -- 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
1580 | N_Op_Divide
1581 | N_Op_Expon
1582 | N_Op_Mod
1583 | N_Op_Multiply
1584 | N_Op_Rem
1585 | N_Op_Subtract
1586 =>
1589 when N_Op_Abs
1590 | N_Op_Minus
1591 | N_Op_Plus
1592 =>
1598 else
1602 -- If in ASIS_Mode, propagate operand types to original actuals of
1603 -- function call, which would otherwise not be fully resolved. If
1604 -- the call has already been constant-folded, nothing to do. We
1605 -- relocate the operand nodes rather than copy them, to preserve
1606 -- original_node pointers, given that the operands themselves may
1607 -- have been rewritten. If the call was itself a rewriting of an
1608 -- operator node, nothing to do.
1610 if ASIS_Mode
1613 then
1614 declare
1622 begin
1627 -- If the original call has named associations, replace the
1628 -- explicit actual parameter in the association with the proper
1629 -- resolved operand.
1634 then
1637 else
1642 else
1649 then
1652 else
1657 else
1661 else
1665 else
1675 -------------------
1676 -- Operator_Kind --
1677 -------------------
1679 function Operator_Kind
1682 is
1685 begin
1686 -- Use CASE statement or array???
1723 else
1727 -- Unary operators
1729 else
1738 else
1746 ----------------------------
1747 -- Preanalyze_And_Resolve --
1748 ----------------------------
1753 begin
1757 -- Normally, we suppress all checks for this preanalysis. There is no
1758 -- point in processing them now, since they will be applied properly
1759 -- and in the proper location when the default expressions reanalyzed
1760 -- and reexpanded later on. We will also have more information at that
1761 -- point for possible suppression of individual checks.
1763 -- However, in SPARK mode, most expansion is suppressed, and this
1764 -- later reanalysis and reexpansion may not occur. SPARK mode does
1765 -- require the setting of checking flags for proof purposes, so we
1766 -- do the SPARK preanalysis without suppressing checks.
1768 -- This special handling for SPARK mode is required for example in the
1769 -- case of Ada 2012 constructs such as quantified expressions, which are
1770 -- expanded in two separate steps.
1774 else
1778 Expander_Mode_Restore;
1782 -- Version without context type
1787 begin
1794 Expander_Mode_Restore;
1798 ----------------------------------
1799 -- Replace_Actual_Discriminants --
1800 ----------------------------------
1807 -- Comment needed???
1809 -------------------
1810 -- Process_Discr --
1811 -------------------
1816 begin
1822 then
1838 -- Start of processing for Replace_Actual_Discriminants
1840 begin
1854 else
1859 -------------
1860 -- Resolve --
1861 -------------
1877 -- Determine whether a node comes from a predefined library unit or
1878 -- Standard.
1881 -- Try and fix up a literal so that it matches its expected type. New
1882 -- literals are manufactured if necessary to avoid cascaded errors.
1885 -- Additional diagnostics when an ambiguous call has an ambiguous
1886 -- argument (typically a controlling actual).
1889 -- Called when attempt at resolving current expression fails
1891 ------------------------------------
1892 -- Comes_From_Predefined_Lib_Unit --
1893 -------------------------------------
1896 begin
1897 return
1899 or else Is_Predefined_File_Name
1903 --------------------
1904 -- Patch_Up_Value --
1905 --------------------
1908 begin
1925 then
1930 Char_Literal_Value =>
1946 -------------------------------
1947 -- Report_Ambiguous_Argument --
1948 -------------------------------
1955 begin
1959 then
1962 -- Could use comments on what is going on here???
1970 else
1979 -----------------------
1980 -- Resolution_Failed --
1981 -----------------------
1984 begin
1987 -- Set the type to the desired one to minimize cascaded errors. Note
1988 -- that this is an approximation and does not work in all cases.
1995 -- The caller will return without calling the expander, so we need
1996 -- to set the analyzed flag. Note that it is fine to set Analyzed
1997 -- to True even if we are in the middle of a shallow analysis,
1998 -- (see the spec of sem for more details) since this is an error
1999 -- situation anyway, and there is no point in repeating the
2000 -- analysis later (indeed it won't work to repeat it later, since
2001 -- we haven't got a clear resolution of which entity is being
2002 -- referenced.)
2008 -- Start of processing for Resolve
2010 begin
2015 -- Access attribute on remote subprogram cannot be used for a non-remote
2016 -- access-to-subprogram type.
2020 Name_Unrestricted_Access,
2021 Name_Unchecked_Access)
2027 then
2028 Error_Msg_N
2034 -- If the context is a Remote_Access_To_Subprogram, access attributes
2035 -- must be resolved with the corresponding fat pointer. There is no need
2036 -- to check for the attribute name since the return type of an
2037 -- attribute is never a remote type.
2042 then
2043 declare
2051 begin
2052 -- Check that Typ is a remote access-to-subprogram type
2056 -- Prefix (N) must statically denote a remote subprogram
2057 -- declared in a package specification.
2061 Attr = Attribute_Unrestricted_Access
2062 then
2077 or else
2079 then
2081 Error_Msg_N
2083 N);
2086 -- If we are generating code in distributed mode, perform
2087 -- semantic checks against corresponding remote entities.
2089 if Expander_Active
2091 then
2092 Check_Subtype_Conformant
2094 Old_Id => Designated_Type
2120 then
2125 -- Return if already analyzed
2132 -- Any case of Any_Type as the Etype value means that we had a
2133 -- previous error.
2142 -- The resolution of an Expression_With_Actions is determined by
2143 -- its Expression.
2151 -- If not overloaded, then we know the type, and all that needs doing
2152 -- is to check that this type is compatible with the context.
2158 -- In the overloaded case, we must select the interpretation that
2159 -- is compatible with the context (i.e. the type passed to Resolve)
2161 else
2162 -- Loop through possible interpretations
2171 -- We are only interested in interpretations that are compatible
2172 -- with the expected type, any other interpretations are ignored.
2177 Write_Eol;
2180 else
2181 -- Skip the current interpretation if it is disabled by an
2182 -- abstract operator. This action is performed only when the
2183 -- type against which we are resolving is the same as the
2184 -- type of the interpretation.
2191 then
2199 -- First matching interpretation
2207 -- Matching interpretation that is not the first, maybe an
2208 -- error, but there are some cases where preference rules are
2209 -- used to choose between the two possibilities. These and
2210 -- some more obscure cases are handled in Disambiguate.
2212 else
2213 -- If the current statement is part of a predefined library
2214 -- unit, then all interpretations which come from user level
2215 -- packages should not be considered. Check previous and
2216 -- current one.
2224 -- Previous interpretation must be discarded
2234 -- Otherwise apply further disambiguation steps
2239 -- Disambiguation has succeeded. Skip the remaining
2240 -- interpretations.
2250 else
2251 -- Before we issue an ambiguity complaint, check for the
2252 -- case of a subprogram call where at least one of the
2253 -- arguments is Any_Type, and if so suppress the message,
2254 -- since it is a cascaded error. This can also happen for
2255 -- a generalized indexing operation.
2260 then
2261 declare
2265 begin
2281 Write_Eol;
2294 then
2299 then
2303 -- Not that special case, so issue message using the flag
2304 -- Ambiguous to control printing of the header message
2305 -- only at the start of an ambiguous set.
2310 then
2311 Error_Msg_N
2314 else
2315 Error_Msg_NE -- CODEFIX
2323 Error_Msg_N
2325 else
2326 Error_Msg_N -- CODEFIX
2332 then
2333 Report_Ambiguous_Argument;
2339 -- By default, the error message refers to the candidate
2340 -- interpretation. But if it is a predefined operator, it
2341 -- is implicitly declared at the declaration of the type
2342 -- of the operand. Recover the sloc of that declaration
2343 -- for the error message.
2349 Standard_Standard
2350 then
2355 then
2363 Standard_Standard
2364 then
2369 then
2373 -- If this is an indirect call, use the subprogram_type
2374 -- in the message, to have a meaningful location. Also
2375 -- indicate if this is an inherited operation, created
2376 -- by a type declaration.
2381 then
2383 Error_Msg_Sloc :=
2385 else
2392 then
2393 -- Special-case the message for universal_fixed
2394 -- operators, which are not declared with the type
2395 -- of the operand, but appear forever in Standard.
2399 then
2400 Error_Msg_N
2403 else
2404 Error_Msg_N
2408 elsif
2410 then
2411 Error_Msg_N
2413 else
2414 Error_Msg_N -- CODEFIX
2421 -- We have a matching interpretation, Expr_Type is the type
2422 -- from this interpretation, and Seen is the entity.
2424 -- For an operator, just set the entity name. The type will be
2425 -- set by the specific operator resolution routine.
2440 -- AI05-0139-2: Expression is overloaded because type has
2441 -- implicit dereference. If type matches context, no implicit
2442 -- dereference is involved.
2453 then
2454 -- If the node is a general indexing, the dereference is
2455 -- is inserted when resolving the rewritten form, else
2456 -- insert it now.
2460 then
2464 -- For an explicit dereference, attribute reference, range,
2465 -- short-circuit form (which is not an operator node), or call
2466 -- with a name that is an explicit dereference, there is
2467 -- nothing to be done at this point.
2470 N_And_Then,
2471 N_Explicit_Dereference,
2472 N_Identifier,
2473 N_Indexed_Component,
2474 N_Or_Else,
2475 N_Range,
2476 N_Selected_Component,
2477 N_Slice)
2479 then
2482 -- For procedure or function calls, set the type of the name,
2483 -- and also the entity pointer for the prefix.
2487 then
2494 then
2499 -- For all other cases, just set the type of the Name
2501 else
2509 -- Move to next interpretation
2517 -- At this stage Found indicates whether or not an acceptable
2518 -- interpretation exists. If not, then we have an error, except that if
2519 -- the context is Any_Type as a result of some other error, then we
2520 -- suppress the error report.
2525 -- If type we are looking for is Void, then this is the procedure
2526 -- call case, and the error is simply that what we gave is not a
2527 -- procedure name (we think of procedure calls as expressions with
2528 -- types internally, but the user doesn't think of them this way).
2532 -- Special case message if function used as a procedure
2537 then
2538 Error_Msg_NE
2542 -- Otherwise give general message (not clear what cases this
2543 -- covers, but no harm in providing for them).
2545 else
2551 -- Otherwise we do have a subexpression with the wrong type
2553 -- Check for the case of an allocator which uses an access type
2554 -- instead of the designated type. This is a common error and we
2555 -- specialize the message, posting an error on the operand of the
2556 -- allocator, complaining that we expected the designated type of
2557 -- the allocator.
2563 then
2567 -- Check for view mismatch on Null in instances, for which the
2568 -- view-swapping mechanism has no identifier.
2574 then
2579 -- Check for an aggregate. Sometimes we can get bogus aggregates
2580 -- from misuse of parentheses, and we are about to complain about
2581 -- the aggregate without even looking inside it.
2583 -- Instead, if we have an aggregate of type Any_Composite, then
2584 -- analyze and resolve the component fields, and then only issue
2585 -- another message if we get no errors doing this (otherwise
2586 -- assume that the errors in the aggregate caused the problem).
2590 then
2591 -- Disable expansion in any case. If there is a type mismatch
2592 -- it may be fatal to try to expand the aggregate. The flag
2593 -- would otherwise be set to false when the error is posted.
2597 declare
2599 -- Check one aggregate, and set Found to True if we have a
2600 -- definite error in any of its elements
2603 -- Check one element of aggregate and set Found to True if
2604 -- we definitely have an error in the element.
2606 ----------------
2607 -- Check_Aggr --
2608 ----------------
2613 begin
2626 -- If this is a default-initialized component, then
2627 -- there is nothing to check. The box will be
2628 -- replaced by the appropriate call during late
2629 -- expansion.
2633 then
2642 ----------------
2643 -- Check_Elmt --
2644 ----------------
2647 begin
2648 -- If we have a nested aggregate, go inside it (to
2649 -- attempt a naked analyze-resolve of the aggregate can
2650 -- cause undesirable cascaded errors). Do not resolve
2651 -- expression if it needs a type from context, as for
2652 -- integer * fixed expression.
2657 else
2662 then
2672 begin
2677 -- Looks like we have a type error, but check for special case
2678 -- of Address wanted, integer found, with the configuration pragma
2679 -- Allow_Integer_Address active. If we have this case, introduce
2680 -- an unchecked conversion to allow the integer expression to be
2681 -- treated as an Address. The reverse case of integer wanted,
2682 -- Address found, is treated in an analogous manner.
2689 -- Under relaxed RM semantics silently replace occurrences of null
2690 -- by System.Address_Null.
2698 -- That special Allow_Integer_Address check did not apply, so we
2699 -- have a real type error. If an error message was issued already,
2700 -- Found got reset to True, so if it's still False, issue standard
2701 -- Wrong_Type message.
2705 declare
2708 begin
2714 -- Protected operation: retrieve operation name
2718 else
2723 Error_Msg_NE
2729 declare
2733 begin
2740 Error_Msg_NE
2746 else
2750 else
2756 Resolution_Failed;
2759 -- Test if we have more than one interpretation for the context
2762 Resolution_Failed;
2765 -- Only one intepretation
2767 else
2768 -- In Ada 2005, if we have something like "X : T := 2 + 2;", where
2769 -- the "+" on T is abstract, and the operands are of universal type,
2770 -- the above code will have (incorrectly) resolved the "+" to the
2771 -- universal one in Standard. Therefore check for this case and give
2772 -- an error. We can't do this earlier, because it would cause legal
2773 -- cases to get errors (when some other type has an abstract "+").
2779 then
2784 then
2785 Error_Msg_NE
2794 -- Here we have an acceptable interpretation for the context
2796 -- Propagate type information and normalize tree for various
2797 -- predefined operations. If the context only imposes a class of
2798 -- types, rather than a specific type, propagate the actual type
2799 -- downward.
2805 Typ = Any_Discrete
2806 then
2809 -- Any_Fixed is legal in a real context only if a specific fixed-
2810 -- point type is imposed. If Norman Cohen can be confused by this,
2811 -- it deserves a separate message.
2815 then
2822 -- A user-defined operator is transformed into a function call at
2823 -- this point, so that further processing knows that operators are
2824 -- really operators (i.e. are predefined operators). User-defined
2825 -- operators that are intrinsic are just renamings of the predefined
2826 -- ones, and need not be turned into calls either, but if they rename
2827 -- a different operator, we must transform the node accordingly.
2828 -- Instantiations of Unchecked_Conversion are intrinsic but are
2829 -- treated as functions, even if given an operator designator.
2834 then
2839 and then
2841 N_Subprogram_Renaming_Declaration
2842 then
2845 -- If the node is rewritten, it will be fully resolved in
2846 -- Rewrite_Renamed_Operator.
2855 when N_Aggregate =>
2856 Resolve_Aggregate (N, Ctx_Type);
2858 when N_Allocator =>
2859 Resolve_Allocator (N, Ctx_Type);
2861 when N_Short_Circuit =>
2862 Resolve_Short_Circuit (N, Ctx_Type);
2864 when N_Attribute_Reference =>
2865 Resolve_Attribute (N, Ctx_Type);
2867 when N_Case_Expression =>
2868 Resolve_Case_Expression (N, Ctx_Type);
2870 when N_Character_Literal =>
2871 Resolve_Character_Literal (N, Ctx_Type);
2873 when N_Delta_Aggregate =>
2874 Resolve_Delta_Aggregate (N, Ctx_Type);
2876 when N_Expanded_Name =>
2877 Resolve_Entity_Name (N, Ctx_Type);
2879 when N_Explicit_Dereference =>
2880 Resolve_Explicit_Dereference (N, Ctx_Type);
2882 when N_Expression_With_Actions =>
2883 Resolve_Expression_With_Actions (N, Ctx_Type);
2885 when N_Extension_Aggregate =>
2886 Resolve_Extension_Aggregate (N, Ctx_Type);
2888 when N_Function_Call =>
2889 Resolve_Call (N, Ctx_Type);
2891 when N_Identifier =>
2892 Resolve_Entity_Name (N, Ctx_Type);
2894 when N_If_Expression =>
2895 Resolve_If_Expression (N, Ctx_Type);
2897 when N_Indexed_Component =>
2898 Resolve_Indexed_Component (N, Ctx_Type);
2900 when N_Integer_Literal =>
2901 Resolve_Integer_Literal (N, Ctx_Type);
2903 when N_Membership_Test =>
2904 Resolve_Membership_Op (N, Ctx_Type);
2906 when N_Null =>
2907 Resolve_Null (N, Ctx_Type);
2909 when N_Op_And
2910 | N_Op_Or
2911 | N_Op_Xor
2912 =>
2913 Resolve_Logical_Op (N, Ctx_Type);
2915 when N_Op_Eq
2916 | N_Op_Ne
2917 =>
2918 Resolve_Equality_Op (N, Ctx_Type);
2920 when N_Op_Ge
2921 | N_Op_Gt
2922 | N_Op_Le
2923 | N_Op_Lt
2924 =>
2925 Resolve_Comparison_Op (N, Ctx_Type);
2927 when N_Op_Not =>
2928 Resolve_Op_Not (N, Ctx_Type);
2930 when N_Op_Add
2931 | N_Op_Divide
2932 | N_Op_Mod
2933 | N_Op_Multiply
2934 | N_Op_Rem
2935 | N_Op_Subtract
2936 =>
2937 Resolve_Arithmetic_Op (N, Ctx_Type);
2939 when N_Op_Concat =>
2940 Resolve_Op_Concat (N, Ctx_Type);
2942 when N_Op_Expon =>
2943 Resolve_Op_Expon (N, Ctx_Type);
2945 when N_Op_Abs
2946 | N_Op_Minus
2947 | N_Op_Plus
2948 =>
2949 Resolve_Unary_Op (N, Ctx_Type);
2951 when N_Op_Shift =>
2952 Resolve_Shift (N, Ctx_Type);
2954 when N_Procedure_Call_Statement =>
2955 Resolve_Call (N, Ctx_Type);
2957 when N_Operator_Symbol =>
2958 Resolve_Operator_Symbol (N, Ctx_Type);
2960 when N_Qualified_Expression =>
2961 Resolve_Qualified_Expression (N, Ctx_Type);
2963 -- Why is the following null, needs a comment ???
2965 when N_Quantified_Expression =>
2966 null;
2968 when N_Raise_Expression =>
2969 Resolve_Raise_Expression (N, Ctx_Type);
2971 when N_Raise_xxx_Error =>
2972 Set_Etype (N, Ctx_Type);
2974 when N_Range =>
2975 Resolve_Range (N, Ctx_Type);
2977 when N_Real_Literal =>
2978 Resolve_Real_Literal (N, Ctx_Type);
2980 when N_Reference =>
2981 Resolve_Reference (N, Ctx_Type);
2983 when N_Selected_Component =>
2984 Resolve_Selected_Component (N, Ctx_Type);
2986 when N_Slice =>
2987 Resolve_Slice (N, Ctx_Type);
2989 when N_String_Literal =>
2990 Resolve_String_Literal (N, Ctx_Type);
2992 when N_Target_Name =>
2993 Resolve_Target_Name (N, Ctx_Type);
2995 when N_Type_Conversion =>
2996 Resolve_Type_Conversion (N, Ctx_Type);
2998 when N_Unchecked_Expression =>
2999 Resolve_Unchecked_Expression (N, Ctx_Type);
3001 when N_Unchecked_Type_Conversion =>
3002 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
3003 end case;
3005 -- Ada 2012 (AI05-0149): Apply an (implicit) conversion to an
3006 -- expression of an anonymous access type that occurs in the context
3007 -- of a named general access type, except when the expression is that
3008 -- of a membership test. This ensures proper legality checking in
3009 -- terms of allowed conversions (expressions that would be illegal to
3010 -- convert implicitly are allowed in membership tests).
3012 if Ada_Version >= Ada_2012
3013 and then Ekind (Ctx_Type) = E_General_Access_Type
3014 and then Ekind (Etype (N)) = E_Anonymous_Access_Type
3015 and then Nkind (Parent (N)) not in N_Membership_Test
3016 then
3017 Rewrite (N, Convert_To (Ctx_Type, Relocate_Node (N)));
3018 Analyze_And_Resolve (N, Ctx_Type);
3019 end if;
3021 -- If the subexpression was replaced by a non-subexpression, then
3022 -- all we do is to expand it. The only legitimate case we know of
3023 -- is converting procedure call statement to entry call statements,
3024 -- but there may be others, so we are making this test general.
3026 if Nkind (N) not in N_Subexpr then
3027 Debug_A_Exit ("resolving ", N, " (done)");
3028 Expand (N);
3029 return;
3030 end if;
3032 -- The expression is definitely NOT overloaded at this point, so
3033 -- we reset the Is_Overloaded flag to avoid any confusion when
3034 -- reanalyzing the node.
3036 Set_Is_Overloaded (N, False);
3038 -- Freeze expression type, entity if it is a name, and designated
3039 -- type if it is an allocator (RM 13.14(10,11,13)).
3041 -- Now that the resolution of the type of the node is complete, and
3042 -- we did not detect an error, we can expand this node. We skip the
3043 -- expand call if we are in a default expression, see section
3044 -- "Handling of Default Expressions" in Sem spec.
3046 Debug_A_Exit ("resolving ", N, " (done)");
3048 -- We unconditionally freeze the expression, even if we are in
3049 -- default expression mode (the Freeze_Expression routine tests this
3050 -- flag and only freezes static types if it is set).
3052 -- Ada 2012 (AI05-177): The declaration of an expression function
3053 -- does not cause freezing, but we never reach here in that case.
3054 -- Here we are resolving the corresponding expanded body, so we do
3055 -- need to perform normal freezing.
3057 Freeze_Expression (N);
3059 -- Now we can do the expansion
3061 Expand (N);
3062 end if;
3063 end Resolve;
3065 -------------
3066 -- Resolve --
3067 -------------
3069 -- Version with check(s) suppressed
3071 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
3072 begin
3073 if Suppress = All_Checks then
3074 declare
3075 Sva : constant Suppress_Array := Scope_Suppress.Suppress;
3076 begin
3077 Scope_Suppress.Suppress := (others => True);
3078 Resolve (N, Typ);
3079 Scope_Suppress.Suppress := Sva;
3080 end;
3082 else
3083 declare
3084 Svg : constant Boolean := Scope_Suppress.Suppress (Suppress);
3085 begin
3086 Scope_Suppress.Suppress (Suppress) := True;
3087 Resolve (N, Typ);
3088 Scope_Suppress.Suppress (Suppress) := Svg;
3089 end;
3090 end if;
3091 end Resolve;
3093 -------------
3094 -- Resolve --
3095 -------------
3097 -- Version with implicit type
3099 procedure Resolve (N : Node_Id) is
3100 begin
3101 Resolve (N, Etype (N));
3102 end Resolve;
3104 ---------------------
3105 -- Resolve_Actuals --
3106 ---------------------
3108 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
3109 Loc : constant Source_Ptr := Sloc (N);
3110 A : Node_Id;
3111 A_Id : Entity_Id;
3112 A_Typ : Entity_Id;
3113 F : Entity_Id;
3114 F_Typ : Entity_Id;
3115 Prev : Node_Id := Empty;
3116 Orig_A : Node_Id;
3117 Real_F : Entity_Id;
3119 Real_Subp : Entity_Id;
3120 -- If the subprogram being called is an inherited operation for
3121 -- a formal derived type in an instance, Real_Subp is the subprogram
3122 -- that will be called. It may have different formal names than the
3123 -- operation of the formal in the generic, so after actual is resolved
3124 -- the name of the actual in a named association must carry the name
3125 -- of the actual of the subprogram being called.
3127 procedure Check_Aliased_Parameter;
3128 -- Check rules on aliased parameters and related accessibility rules
3129 -- in (RM 3.10.2 (10.2-10.4)).
3131 procedure Check_Argument_Order;
3132 -- Performs a check for the case where the actuals are all simple
3133 -- identifiers that correspond to the formal names, but in the wrong
3134 -- order, which is considered suspicious and cause for a warning.
3136 procedure Check_Prefixed_Call;
3137 -- If the original node is an overloaded call in prefix notation,
3139 -- Try_Object_Operation has already verified that there is a valid
3140 -- interpretation, but the form of the actual can only be determined
3141 -- once the primitive operation is identified.
3144 -- Emit an error concerning the illegal usage of an effectively volatile
3145 -- object in interfering context (SPARK RM 7.13(12)).
3148 -- If the actual is missing in a call, insert in the actuals list
3149 -- an instance of the default expression. The insertion is always
3150 -- a named association.
3152 procedure Property_Error
3156 -- Emit an error concerning variable Var with entity Var_Id that has
3157 -- enabled property Prop_Nam when it acts as an actual parameter in a
3158 -- call and the corresponding formal parameter is of mode IN.
3161 -- Check whether T1 and T2, or their full views, are derived from a
3162 -- common type. Used to enforce the restrictions on array conversions
3163 -- of AI95-00246.
3166 -- Predicate to determine whether an actual that is a concatenation
3167 -- will be evaluated statically and does not need a transient scope.
3168 -- This must be determined before the actual is resolved and expanded
3169 -- because if needed the transient scope must be introduced earlier.
3171 -----------------------------
3172 -- Check_Aliased_Parameter --
3173 -----------------------------
3178 begin
3186 else
3193 -- In a generic body assume the worst for generic formals:
3194 -- they can have a constrained partial view (AI05-041).
3200 then
3203 else
3208 else
3220 then
3228 then
3229 Error_Msg_N
3235 --------------------------
3236 -- Check_Argument_Order --
3237 --------------------------
3240 begin
3241 -- Nothing to do if no parameters, or original node is neither a
3242 -- function call nor a procedure call statement (happens in the
3243 -- operator-transformed-to-function call case), or the call does
3244 -- not come from source, or this warning is off.
3246 if not Warn_On_Parameter_Order
3250 then
3254 declare
3257 begin
3258 -- Nothing to do if only one parameter
3264 -- Here if at least two arguments
3266 declare
3272 -- Set True if an out of order case is found
3274 begin
3275 -- Collect identifier names of actuals, fail if any actual is
3276 -- not a simple identifier, and record max length of name.
3282 else
3288 -- If we got this far, all actuals are identifiers and the list
3289 -- of their names is stored in the Actuals array.
3294 -- If we ran out of formals, that's odd, probably an error
3295 -- which will be detected elsewhere, but abandon the search.
3301 -- If name matches and is in order OK
3306 else
3307 -- If no match, see if it is elsewhere in list and if so
3308 -- flag potential wrong order if type is compatible.
3312 and then
3314 then
3320 -- No match
3328 -- If Formals left over, also probably an error, skip warning
3334 -- Here we give the warning if something was out of order
3337 Error_Msg_N
3344 -------------------------
3345 -- Check_Prefixed_Call --
3346 -------------------------
3355 begin
3356 -- Check whether the call is a prefixed call, with or without
3357 -- additional actuals.
3360 or else
3366 then
3369 then
3370 -- Introduce dereference on object in prefix
3372 New_A :=
3380 then
3381 -- Introduce an implicit 'Access in prefix
3384 Error_Msg_NE
3400 ---------------------------------------
3401 -- Flag_Effectively_Volatile_Objects --
3402 ---------------------------------------
3406 -- Determine whether arbitrary node N denotes an effectively volatile
3407 -- object and if it does, emit an error.
3409 -----------------
3410 -- Flag_Object --
3411 -----------------
3416 begin
3417 -- Do not consider nested function calls because they have already
3418 -- been processed during their own resolution.
3430 then
3431 Error_Msg_N
3443 -- Start of processing for Flag_Effectively_Volatile_Objects
3445 begin
3449 --------------------
3450 -- Insert_Default --
3451 --------------------
3457 begin
3458 -- Missing argument in call, nothing to insert
3463 else
3464 -- Note that we do a full New_Copy_Tree, so that any associated
3465 -- Itypes are properly copied. This may not be needed any more,
3466 -- but it does no harm as a safety measure. Defaults of a generic
3467 -- formal may be out of bounds of the corresponding actual (see
3468 -- cc1311b) and an additional check may be required.
3470 Actval :=
3471 New_Copy_Tree
3476 -- Propagate dimension information, if any.
3482 then
3488 then
3491 then
3492 -- If default is a real literal, do not introduce a
3493 -- conversion whose effect may depend on the run-time
3494 -- size of universal real.
3498 else
3509 -- Resolve aggregates with their base type, to avoid scope
3510 -- anomalies: the subtype was first built in the subprogram
3511 -- declaration, and the current call may be nested.
3515 else
3519 else
3522 -- See note above concerning aggregates
3526 then
3529 -- Resolve entities with their own type, which may differ from
3530 -- the type of a reference in a generic context (the view
3531 -- swapping mechanism did not anticipate the re-analysis of
3532 -- default values in calls).
3537 else
3542 -- If default is a tag indeterminate function call, propagate tag
3543 -- to obtain proper dispatching.
3547 then
3552 -- If the default expression raises constraint error, then just
3553 -- silently replace it with an N_Raise_Constraint_Error node, since
3554 -- we already gave the warning on the subprogram spec. If node is
3555 -- already a Raise_Constraint_Error leave as is, to prevent loops in
3556 -- the warnings removal machinery.
3560 then
3568 Assoc :=
3573 -- Case of insertion is first named actual
3577 then
3584 else
3588 else
3592 -- Case of insertion is not first named actual
3594 else
3595 Set_Next_Named_Actual
3607 --------------------
3608 -- Property_Error --
3609 --------------------
3611 procedure Property_Error
3615 is
3616 begin
3618 Error_Msg_NE
3624 -------------------
3625 -- Same_Ancestor --
3626 -------------------
3632 begin
3635 then
3641 then
3648 --------------------------
3649 -- Static_Concatenation --
3650 --------------------------
3653 begin
3660 -- Concatenation is static when both operands are static and
3661 -- the concatenation operator is a predefined one.
3664 and then
3666 and then
3671 declare
3673 begin
3676 and then
3680 else
3686 -- Start of processing for Resolve_Actuals
3688 begin
3689 Check_Argument_Order;
3693 and then In_Instance
3696 then
3698 else
3703 Check_Prefixed_Call;
3717 -- If we have an error in any actual or formal, indicated by a type
3718 -- of Any_Type, then abandon resolution attempt, and set result type
3719 -- to Any_Type. Skip this if the actual is a Raise_Expression, whose
3720 -- type is imposed from context.
3724 then
3731 -- Case where actual is present
3733 -- If the actual is an entity, generate a reference to it now. We
3734 -- do this before the actual is resolved, because a formal of some
3735 -- protected subprogram, or a task discriminant, will be rewritten
3736 -- during expansion, and the source entity reference may be lost.
3741 then
3747 then
3754 -- RM 6.4.1(12): For an out parameter that is passed by
3755 -- copy, the formal parameter object is created, and:
3757 -- * For an access type, the formal parameter is initialized
3758 -- from the value of the actual, without checking that the
3759 -- value satisfies any constraint, any predicate, or any
3760 -- exclusion of the null value.
3762 -- * For a scalar type that has the Default_Value aspect
3763 -- specified, the formal parameter is initialized from the
3764 -- value of the actual, without checking that the value
3765 -- satisfies any constraint or any predicate.
3766 -- I do not understand why this case is included??? this is
3767 -- not a case where an OUT parameter is treated as IN OUT.
3769 -- * For a composite type with discriminants or that has
3770 -- implicit initial values for any subcomponents, the
3771 -- behavior is as for an in out parameter passed by copy.
3773 -- Hence for these cases we generate the read reference now
3774 -- (the write reference will be generated later by
3775 -- Note_Possible_Modification).
3778 and then
3780 or else
3782 and then
3784 or else
3787 or else Is_Partially_Initialized_Type
3789 then
3799 then
3800 -- If style checking mode on, check match of formal name
3808 -- If the formal is Out or In_Out, do not resolve and expand the
3809 -- conversion, because it is subsequently expanded into explicit
3810 -- temporaries and assignments. However, the object of the
3811 -- conversion can be resolved. An exception is the case of tagged
3812 -- type conversion with a class-wide actual. In that case we want
3813 -- the tag check to occur and no temporary will be needed (no
3814 -- representation change can occur) and the parameter is passed by
3815 -- reference, so we go ahead and resolve the type conversion.
3816 -- Another exception is the case of reference to component or
3817 -- subcomponent of a bit-packed array, in which case we want to
3818 -- defer expansion to the point the in and out assignments are
3819 -- performed.
3824 then
3827 then
3828 -- In a view conversion, the conversion must be legal in
3829 -- both directions, and thus both component types must be
3830 -- aliased, or neither (4.6 (8)).
3832 -- The extra rule in 4.6 (24.9.2) seems unduly restrictive:
3833 -- the privacy requirement should not apply to generic
3834 -- types, and should be checked in an instance. ARG query
3835 -- is in order ???
3839 then
3840 Error_Msg_N
3844 -- Comment here??? what set of cases???
3846 elsif
3848 then
3849 -- Check view conv between unrelated by ref array types
3853 then
3854 Error_Msg_N
3858 -- In Ada 2005 mode, check view conversion component
3859 -- type cannot be private, tagged, or volatile. Note
3860 -- that we only apply this to source conversions. The
3861 -- generated code can contain conversions which are
3862 -- not subject to this test, and we cannot extract the
3863 -- component type in such cases since it is not present.
3867 then
3868 declare
3870 Component_Type
3872 begin
3877 then
3878 Error_Msg_N
3889 -- Resolve expression if conversion is all OK
3894 then
3898 -- If the actual is a function call that returns a limited
3899 -- unconstrained object that needs finalization, create a
3900 -- transient scope for it, so that it can receive the proper
3901 -- finalization list.
3906 and then Expander_Active
3908 then
3912 -- A small optimization: if one of the actuals is a concatenation
3913 -- create a block around a procedure call to recover stack space.
3914 -- This alleviates stack usage when several procedure calls in
3915 -- the same statement list use concatenation. We do not perform
3916 -- this wrapping for code statements, where the argument is a
3917 -- static string, and we want to preserve warnings involving
3918 -- sequences of such statements.
3922 and then Expander_Active
3923 and then
3927 then
3931 else
3935 and then
3938 then
3939 Error_Msg_N
3952 -- (Ada 2005: AI-251): If the actual is an allocator whose
3953 -- directly designated type is a class-wide interface, we build
3954 -- an anonymous access type to use it as the type of the
3955 -- allocator. Later, when the subprogram call is expanded, if
3956 -- the interface has a secondary dispatch table the expander
3957 -- will add a type conversion to force the correct displacement
3958 -- of the pointer.
3961 declare
3967 begin
3970 then
3973 Set_Directly_Designated_Type
3978 -- Ada 2005, AI-162:If the actual is an allocator, the
3979 -- innermost enclosing statement is the master of the
3980 -- created object. This needs to be done with expansion
3981 -- enabled only, otherwise the transient scope will not
3982 -- be removed in the expansion of the wrapped construct.
3985 and then Expander_Active
3986 then
3996 -- (Ada 2005): The call may be to a primitive operation of a
3997 -- tagged synchronized type, declared outside of the type. In
3998 -- this case the controlling actual must be converted to its
3999 -- corresponding record type, which is the formal type. The
4000 -- actual may be a subtype, either because of a constraint or
4001 -- because it is a generic actual, so use base type to locate
4002 -- concurrent type.
4009 then
4010 -- If the actual is overloaded, look for an interpretation
4011 -- that has a synchronized type.
4016 else
4017 declare
4021 begin
4026 then
4036 declare
4039 begin
4042 else
4046 -- Tagged synchronized type (case 1): the actual is a
4047 -- concurrent type.
4051 then
4053 Unchecked_Convert_To
4057 -- Tagged synchronized type (case 2): the formal is a
4058 -- concurrent type.
4061 and then Present
4066 then
4069 -- Common case
4071 else
4076 -- Not a synchronized operation
4078 else
4086 -- An actual cannot be an untagged formal incomplete type
4091 then
4092 Error_Msg_N
4098 N_Procedure_Call_Statement)
4099 then
4100 -- In formal mode, check that actual parameters matching
4101 -- formals of tagged types are objects (or ancestor type
4102 -- conversions of objects), not general expressions.
4109 declare
4114 begin
4116 Check_SPARK_05_Restriction
4119 -- In formal mode, the only view conversions are those
4120 -- involving ancestor conversion of an extended type.
4122 elsif not
4128 then
4129 if Ekind_In
4131 then
4132 Check_SPARK_05_Restriction
4135 else
4136 Check_SPARK_05_Restriction
4140 else
4145 else
4149 -- In formal mode, the only view conversions are those
4150 -- involving ancestor conversion of an extended type.
4154 then
4155 Check_SPARK_05_Restriction
4161 -- has warnings suppressed, then we reset Never_Set_In_Source for
4162 -- the calling entity. The reason for this is to catch cases like
4163 -- GNAT.Spitbol.Patterns.Vstring_Var where the called subprogram
4164 -- uses trickery to modify an IN parameter.
4171 then
4175 -- Perform error checks for IN and IN OUT parameters
4179 -- Check unset reference. For scalar parameters, it is clearly
4180 -- wrong to pass an uninitialized value as either an IN or
4181 -- IN-OUT parameter. For composites, it is also clearly an
4182 -- error to pass a completely uninitialized value as an IN
4183 -- parameter, but the case of IN OUT is trickier. We prefer
4184 -- not to give a warning here. For example, suppose there is
4185 -- a routine that sets some component of a record to False.
4186 -- It is perfectly reasonable to make this IN-OUT and allow
4187 -- either initialized or uninitialized records to be passed
4188 -- in this case.
4190 -- For partially initialized composite values, we also avoid
4191 -- warnings, since it is quite likely that we are passing a
4192 -- partially initialized value and only the initialized fields
4193 -- will in fact be read in the subprogram.
4198 then
4202 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
4203 -- actual to a nested call, since this constitutes a reading of
4204 -- the parameter, which is not allowed.
4209 then
4214 -- Case of OUT or IN OUT parameter
4218 -- For an Out parameter, check for useless assignment. Note
4219 -- that we can't set Last_Assignment this early, because we may
4220 -- kill current values in Resolve_Call, and that call would
4221 -- clobber the Last_Assignment field.
4223 -- Note: call Warn_On_Useless_Assignment before doing the check
4224 -- below for Is_OK_Variable_For_Out_Formal so that the setting
4225 -- of Referenced_As_LHS/Referenced_As_Out_Formal properly
4226 -- reflects the last assignment, not this one.
4233 then
4238 -- Validate the form of the actual. Note that the call to
4239 -- Is_OK_Variable_For_Out_Formal generates the required
4240 -- reference in this case.
4242 -- A call to an initialization procedure for an aggregate
4243 -- component may initialize a nested component of a constant
4244 -- designated object. In this context the object is variable.
4248 then
4254 then
4255 Error_Msg_N
4260 Error_Msg_N
4267 -- What's the following about???
4271 else
4272 Kill_All_Checks;
4281 -- Apply appropriate constraint/predicate checks for IN [OUT] case
4285 -- Apply predicate tests except in certain special cases. Note
4286 -- that it might be more consistent to apply these only when
4287 -- expansion is active (in Exp_Ch6.Expand_Actuals), as we do
4288 -- for the outbound predicate tests ??? In any case indicate
4289 -- the function being called, for better warnings if the call
4290 -- leads to an infinite recursion.
4296 -- Apply required constraint checks
4298 -- Gigi looks at the check flag and uses the appropriate types.
4299 -- For now since one flag is used there is an optimization
4300 -- which might not be done in the IN OUT case since Gigi does
4301 -- not do any analysis. More thought required about this ???
4303 -- In fact is this comment obsolete??? doesn't the expander now
4304 -- generate all these tests anyway???
4317 then
4320 -- For view conversions of a discriminated object, apply
4321 -- check to object itself, the conversion alreay has the
4322 -- proper type.
4326 then
4333 then
4339 then
4342 else
4346 -- Ada 2005 (AI-231): Note that the controlling parameter case
4347 -- already existed in Ada 95, which is partially checked
4348 -- elsewhere (see Checks), and we don't want the warning
4349 -- message to differ.
4354 then
4356 Apply_Compile_Time_Constraint_Error
4362 Apply_Compile_Time_Constraint_Error
4371 -- Checks for OUT parameters and IN OUT parameters
4375 -- If there is a type conversion, make sure the return value
4376 -- meets the constraints of the variable before the conversion.
4380 Apply_Scalar_Range_Check
4383 -- In addition, the returned value of the parameter must
4384 -- satisfy the bounds of the object type (see comment
4385 -- below).
4389 else
4390 Apply_Range_Check
4394 -- If no conversion, apply scalar range checks and length check
4395 -- based on the subtype of the actual (NOT that of the formal).
4396 -- This indicates that the check takes place on return from the
4397 -- call. During expansion the required constraint checks are
4398 -- inserted. In GNATprove mode, in the absence of expansion,
4399 -- the flag indicates that the returned value is valid.
4401 else
4407 then
4409 else
4414 -- Note: we do not apply the predicate checks for the case of
4415 -- OUT and IN OUT parameters. They are instead applied in the
4416 -- Expand_Actuals routine in Exp_Ch6.
4419 -- An actual associated with an access parameter is implicitly
4420 -- converted to the anonymous access type of the formal and must
4421 -- satisfy the legality checks for access conversions.
4425 Error_Msg_N
4429 -- If the actual is an access selected component of a variable,
4430 -- the call may modify its designated object. It is reasonable
4431 -- to treat this as a potential modification of the enclosing
4432 -- record, to prevent spurious warnings that it should be
4433 -- declared as a constant, because intuitively programmers
4434 -- regard the designated subcomponent as part of the record.
4439 then
4444 -- Check bad case of atomic/volatile argument (RM C.6(12))
4448 then
4451 then
4452 Error_Msg_NE
4458 then
4459 Error_Msg_NE
4465 -- Check that subprograms don't have improper controlling
4466 -- arguments (RM 3.9.2 (9)).
4468 -- A primitive operation may have an access parameter of an
4469 -- incomplete tagged type, but a dispatching call is illegal
4470 -- if the type is still incomplete.
4476 declare
4478 begin
4482 then
4483 Error_Msg_NE
4494 -- Apply legality rule 3.9.2 (9/1)
4499 and then not In_Instance
4500 then
4505 Error_Msg_NE
4509 -- Apply the checks described in 3.10.2(27): if the context is a
4510 -- specific access-to-object, the actual cannot be class-wide.
4511 -- Use base type to exclude access_to_subprogram cases.
4518 and then
4523 -- Disable these checks for call to imported C++ subprograms
4525 and then not
4529 then
4530 Error_Msg_N
4535 Error_Msg_NE
4540 Check_Aliased_Parameter;
4544 -- If it is a named association, treat the selector_name as a
4545 -- proper identifier, and mark the corresponding entity.
4549 -- Ignore reference in SPARK mode, as it refers to an entity not
4550 -- in scope at the point of reference, so the reference should
4551 -- be ignored for computing effects of subprograms.
4553 and then not GNATprove_Mode
4554 then
4555 -- If subprogram is overridden, use name of formal that
4556 -- is being called.
4562 else
4576 -- The following checks are only relevant when SPARK_Mode is on as
4577 -- they are not standard Ada legality rule. Internally generated
4578 -- temporaries are ignored.
4582 -- An effectively volatile object may act as an actual when the
4583 -- corresponding formal is of a non-scalar effectively volatile
4584 -- type (SPARK RM 7.1.3(11)).
4588 then
4591 -- An effectively volatile object may act as an actual in a
4592 -- call to an instance of Unchecked_Conversion.
4593 -- (SPARK RM 7.1.3(11)).
4598 -- The actual denotes an object
4601 Error_Msg_N
4605 -- Otherwise the actual denotes an expression. Inspect the
4606 -- expression and flag each effectively volatile object with
4607 -- enabled property Async_Writers or Effective_Reads as illegal
4608 -- because it apprears within an interfering context. Note that
4609 -- this is usually done in Resolve_Entity_Name, but when the
4610 -- effectively volatile object appears as an actual in a call,
4611 -- the call must be resolved first.
4613 else
4617 -- Detect an external variable with an enabled property that
4618 -- does not match the mode of the corresponding formal in a
4619 -- procedure call. Functions are not considered because they
4620 -- cannot have effectively volatile formal parameters in the
4621 -- first place.
4628 then
4641 -- A formal parameter of a specific tagged type whose related
4642 -- subprogram is subject to pragma Extensions_Visible with value
4643 -- "False" cannot act as an actual in a subprogram with value
4644 -- "True" (SPARK RM 6.1.7(3)).
4648 Extensions_Visible_True
4649 then
4650 Error_Msg_N
4653 Error_Msg_NE
4657 -- The actual parameter of a Ghost subprogram whose formal is of
4658 -- mode IN OUT or OUT must be a Ghost variable (SPARK RM 6.9(12)).
4666 then
4667 Error_Msg_NE
4673 else
4680 -- Case where actual is not present
4682 else
4683 Insert_Default;
4694 -----------------------
4695 -- Resolve_Allocator --
4696 -----------------------
4708 procedure Check_Allocator_Discrim_Accessibility
4711 -- Check that accessibility level associated with an access discriminant
4712 -- initialized in an allocator by the expression Disc_Exp is not deeper
4713 -- than the level of the allocator type Alloc_Typ. An error message is
4714 -- issued if this condition is violated. Specialized checks are done for
4715 -- the cases of a constraint expression which is an access attribute or
4716 -- an access discriminant.
4719 -- If the allocator is an actual in a call, it is allowed to be class-
4720 -- wide when the context is not because it is a controlling actual.
4722 -------------------------------------------
4723 -- Check_Allocator_Discrim_Accessibility --
4724 -------------------------------------------
4726 procedure Check_Allocator_Discrim_Accessibility
4729 is
4730 begin
4733 then
4734 Error_Msg_N
4737 -- When the expression is an Access attribute the level of the prefix
4738 -- object must not be deeper than that of the allocator's type.
4742 Attribute_Access
4745 then
4746 Error_Msg_N
4748 Disc_Exp);
4750 -- When the expression is an access discriminant the check is against
4751 -- the level of the prefix object.
4757 then
4758 Error_Msg_N
4760 Disc_Exp);
4762 -- All other cases are legal
4764 else
4769 ----------------------------
4770 -- In_Dispatching_Context --
4771 ----------------------------
4776 begin
4782 -- Start of processing for Resolve_Allocator
4784 begin
4785 -- Replace general access with specific type
4795 -- For qualified expression, resolve the expression using the given
4796 -- subtype (nothing to do for type mark, subtype indication)
4801 and then not In_Dispatching_Context
4802 then
4803 Error_Msg_N
4811 -- Allocators generated by the build-in-place expansion mechanism
4812 -- are explicitly marked as coming from source but do not need to be
4813 -- checked for limited initialization. To exclude this case, ensure
4814 -- that the parent of the allocator is a source node.
4819 and then not In_Instance_Body
4820 then
4823 Error_Msg_N
4826 else
4827 Error_Msg_N
4835 -- A qualified expression requires an exact match of the type. Class-
4836 -- wide matching is not allowed.
4841 then
4845 -- Calls to build-in-place functions are not currently supported in
4846 -- allocators for access types associated with a simple storage pool.
4847 -- Supporting such allocators may require passing additional implicit
4848 -- parameters to build-in-place functions (or a significant revision
4849 -- of the current b-i-p implementation to unify the handling for
4850 -- multiple kinds of storage pools). ???
4854 then
4855 declare
4858 begin
4860 and then
4861 Present (Get_Rep_Pragma
4863 then
4864 Error_Msg_N
4871 -- A special accessibility check is needed for allocators that
4872 -- constrain access discriminants. The level of the type of the
4873 -- expression used to constrain an access discriminant cannot be
4874 -- deeper than the type of the allocator (in contrast to access
4875 -- parameters, where the level of the actual can be arbitrary).
4877 -- We can't use Valid_Conversion to perform this check because in
4878 -- general the type of the allocator is unrelated to the type of
4879 -- the access discriminant.
4883 then
4890 then
4893 -- Get the first component expression of the aggregate
4903 else
4907 else
4926 else
4931 else
4940 -- For a subtype mark or subtype indication, freeze the subtype
4942 else
4946 Error_Msg_N
4950 -- A special accessibility check is needed for allocators that
4951 -- constrain access discriminants. The level of the type of the
4952 -- expression used to constrain an access discriminant cannot be
4953 -- deeper than the type of the allocator (in contrast to access
4954 -- parameters, where the level of the actual can be arbitrary).
4955 -- We can't use Valid_Conversion to perform this check because
4956 -- in general the type of the allocator is unrelated to the type
4957 -- of the access discriminant.
4962 then
4972 else
4986 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
4987 -- check that the level of the type of the created object is not deeper
4988 -- than the level of the allocator's access type, since extensions can
4989 -- now occur at deeper levels than their ancestor types. This is a
4990 -- static accessibility level check; a run-time check is also needed in
4991 -- the case of an initialized allocator with a class-wide argument (see
4992 -- Expand_Allocator_Expression).
4996 then
4997 declare
5000 begin
5005 else
5011 then
5014 Error_Msg_N
5023 -- Do not apply Ada 2005 accessibility checks on a class-wide
5024 -- allocator if the type given in the allocator is a formal
5025 -- type. A run-time check will be performed in the instance.
5035 -- Check for allocation from an empty storage pool
5040 -- If the context is an unchecked conversion, as may happen within an
5041 -- inlined subprogram, the allocator is being resolved with its own
5042 -- anonymous type. In that case, if the target type has a specific
5043 -- storage pool, it must be inherited explicitly by the allocator type.
5047 then
5048 Set_Associated_Storage_Pool
5056 -- Check that an allocator with task parts isn't for a nested access
5057 -- type when restriction No_Task_Hierarchy applies.
5061 then
5065 -- An illegal allocator may be rewritten as a raise Program_Error
5066 -- statement.
5070 -- An anonymous access discriminant is the definition of a
5071 -- coextension.
5075 N_Discriminant_Specification
5076 then
5077 declare
5081 begin
5084 -- Ada 2012 AI05-0052: If the designated type of the allocator
5085 -- is limited, then the allocator shall not be used to define
5086 -- the value of an access discriminant unless the discriminated
5087 -- type is immutably limited.
5092 then
5093 Error_Msg_N
5099 -- Avoid marking an allocator as a dynamic coextension if it is
5100 -- within a static construct.
5106 -- Cleanup for potential static coextensions
5108 else
5114 -- Report a simple error: if the designated object is a local task,
5115 -- its body has not been seen yet, and its activation will fail an
5116 -- elaboration check.
5123 then
5129 -- Ada 2012 (AI05-0111-3): Detect an attempt to allocate a task or a
5130 -- type with a task component on a subpool. This action must raise
5131 -- Program_Error at runtime.
5137 then
5149 ---------------------------
5150 -- Resolve_Arithmetic_Op --
5151 ---------------------------
5153 -- Used for resolving all arithmetic operators except exponentiation
5164 -- We do the resolution using the base type, because intermediate values
5165 -- in expressions always are of the base type, not a subtype of it.
5168 -- Returns True if N is in a context that expects "any real type"
5171 -- Return True iff given type is Integer or universal real/integer
5174 -- Choose type of integer literal in fixed-point operation to conform
5175 -- to available fixed-point type. T is the type of the other operand,
5176 -- which is needed to determine the expected type of N.
5179 -- Set operand type to T if universal
5181 -------------------------------
5182 -- Expected_Type_Is_Any_Real --
5183 -------------------------------
5186 begin
5187 -- N is the expression after "delta" in a fixed_point_definition;
5188 -- see RM-3.5.9(6):
5191 N_Decimal_Fixed_Point_Definition,
5193 -- N is one of the bounds in a real_range_specification;
5194 -- see RM-3.5.7(5):
5196 N_Real_Range_Specification,
5198 -- N is the expression of a delta_constraint;
5199 -- see RM-J.3(3):
5201 N_Delta_Constraint);
5204 -----------------------------
5205 -- Is_Integer_Or_Universal --
5206 -----------------------------
5213 begin
5219 else
5225 then
5236 ----------------------------
5237 -- Set_Mixed_Mode_Operand --
5238 ----------------------------
5244 begin
5247 -- A universal integer literal is resolved as standard integer
5248 -- except in the case of a fixed-point result, where we leave it
5249 -- as universal (to be handled by Exp_Fixd later on)
5253 else
5261 then
5262 -- A universal real can appear in a fixed-type context. We resolve
5263 -- the literal with that context, even though this might raise an
5264 -- exception prematurely (the other operand may be zero).
5271 then
5272 -- Integer arg in mixed-mode operation. Resolve with universal
5273 -- type, in case preference rule must be applied.
5279 then
5280 -- Not a mixed-mode operation, resolve with context
5286 -- N may itself be a mixed-mode operation, so use context type
5293 then
5294 -- Must be (fixed * fixed) operation, operand must have one
5295 -- compatible interpretation.
5302 then
5303 -- C * F(X) in a fixed context, where C is a real literal or a
5304 -- fixed-point expression. F must have either a fixed type
5305 -- interpretation or an integer interpretation, but not both.
5312 else
5319 else
5327 -- Reanalyze the literal with the fixed type of the context. If
5328 -- context is Universal_Fixed, we are within a conversion, leave
5329 -- the literal as a universal real because there is no usable
5330 -- fixed type, and the target of the conversion plays no role in
5331 -- the resolution.
5333 declare
5337 begin
5340 else
5346 then
5348 else
5356 else
5361 ----------------------
5362 -- Set_Operand_Type --
5363 ----------------------
5366 begin
5369 then
5374 -- Start of processing for Resolve_Arithmetic_Op
5376 begin
5381 then
5385 -- Special-case for mixed-mode universal expressions or fixed point type
5386 -- operation: each argument is resolved separately. The same treatment
5387 -- is required if one of the operands of a fixed point operation is
5388 -- universal real, since in this case we don't do a conversion to a
5389 -- specific fixed-point type (instead the expander handles the case).
5391 -- Set the type of the node to its universal interpretation because
5392 -- legality checks on an exponentiation operand need the context.
5397 then
5408 or else
5411 then
5416 -- If context is a fixed type and one operand is integer, the other
5417 -- is resolved with the type of the context.
5422 then
5429 then
5433 else
5438 -- Check the rule in RM05-4.5.5(19.1/2) disallowing universal_fixed
5439 -- multiplying operators from being used when the expected type is
5440 -- also universal_fixed. Note that B_Typ will be Universal_Fixed in
5441 -- some cases where the expected type is actually Any_Real;
5442 -- Expected_Type_Is_Any_Real takes care of that case.
5446 then
5450 N_Unchecked_Type_Conversion)
5451 then
5458 else
5461 and then not
5463 N_Unchecked_Type_Conversion)
5464 then
5465 Error_Msg_N
5470 -- The expected type is "any real type" in contexts like
5472 -- type T is delta <universal_fixed-expression> ...
5474 -- in which case we need to set the type to Universal_Real
5475 -- so that static expression evaluation will work properly.
5479 else
5489 then
5494 -- If no previous errors, this is only possible if one operand is
5495 -- overloaded and the context is universal. Resolve as such.
5500 else
5502 and then
5504 then
5508 -- If the context is Universal_Fixed and the operands are also
5509 -- universal fixed, this is an error, unless there is only one
5510 -- applicable fixed_point type (usually Duration).
5518 else
5523 else
5528 -- If one of the arguments was resolved to a non-universal type.
5529 -- label the result of the operation itself with the same type.
5530 -- Do the same for the universal argument, if any.
5542 -- In SPARK, a multiplication or division with operands of fixed point
5543 -- types must be qualified or explicitly converted to identify the
5544 -- result type.
5549 and then
5551 then
5552 Check_SPARK_05_Restriction
5556 -- Set overflow and division checking bit
5563 -- Give warning if explicit division by zero
5567 then
5573 or else
5576 then
5577 -- Specialize the warning message according to the operation.
5578 -- When SPARK_Mode is On, force a warning instead of an error
5579 -- in that case, as this likely corresponds to deactivated
5580 -- code. The following warnings are for the case
5585 -- For division, we have two cases, for float division
5586 -- of an unconstrained float type, on a machine where
5587 -- Machine_Overflows is false, we don't get an exception
5588 -- at run-time, but rather an infinity or Nan. The Nan
5589 -- case is pretty obscure, so just warn about infinities.
5593 and then not Machine_Overflows_On_Target
5594 then
5595 Error_Msg_N
5599 -- For all other cases, we get a Constraint_Error
5601 else
5602 Apply_Compile_Time_Constraint_Error
5609 Apply_Compile_Time_Constraint_Error
5615 Apply_Compile_Time_Constraint_Error
5620 -- Division by zero can only happen with division, rem,
5621 -- and mod operations.
5627 -- In GNATprove mode, we enable the division check so that
5628 -- GNATprove will issue a message if it cannot be proved.
5634 -- Otherwise just set the flag to check at run time
5636 else
5641 -- If Restriction No_Implicit_Conditionals is active, then it is
5642 -- violated if either operand can be negative for mod, or for rem
5643 -- if both operands can be negative.
5647 then
5648 declare
5655 -- Set if corresponding operand might be negative
5657 begin
5658 Determine_Range
5662 Determine_Range
5666 -- Check if we will be generating conditionals. There are two
5667 -- cases where that can happen, first for REM, the only case
5668 -- is largest negative integer mod -1, where the division can
5669 -- overflow, but we still have to give the right result. The
5670 -- front end generates a test for this annoying case. Here we
5671 -- just test if both operands can be negative (that's what the
5672 -- expander does, so we match its logic here).
5674 -- The second case is mod where either operand can be negative.
5675 -- In this case, the back end has to generate additional tests.
5678 or else
5680 then
5691 ------------------
5692 -- Resolve_Call --
5693 ------------------
5696 function Same_Or_Aliased_Subprograms
5699 -- Returns True if the subprogram entity S is the same as E or else
5700 -- S is an alias of E.
5702 ---------------------------------
5703 -- Same_Or_Aliased_Subprograms --
5704 ---------------------------------
5706 function Same_Or_Aliased_Subprograms
5709 is
5711 begin
5715 -- Local variables
5729 -- Start of processing for Resolve_Call
5731 begin
5732 -- The context imposes a unique interpretation with type Typ on a
5733 -- procedure or function call. Find the entity of the subprogram that
5734 -- yields the expected type, and propagate the corresponding formal
5735 -- constraints on the actuals. The caller has established that an
5736 -- interpretation exists, and emitted an error if not unique.
5738 -- First deal with the case of a call to an access-to-subprogram,
5739 -- dereference made explicit in Analyze_Call.
5745 else
5746 -- Find the interpretation whose type (a subprogram type) has a
5747 -- return type that is compatible with the context. Analysis of
5748 -- the node has established that one exists.
5767 -- If the prefix is not an entity, then resolve it
5773 -- For an indirect call, we always invalidate checks, since we do not
5774 -- know whether the subprogram is local or global. Yes we could do
5775 -- better here, e.g. by knowing that there are no local subprograms,
5776 -- but it does not seem worth the effort. Similarly, we kill all
5777 -- knowledge of current constant values.
5779 Kill_Current_Values;
5781 -- If this is a procedure call which is really an entry call, do
5782 -- the conversion of the procedure call to an entry call. Protected
5783 -- operations use the same circuitry because the name in the call
5784 -- can be an arbitrary expression with special resolution rules.
5789 then
5793 -- Kill checks and constant values, as above for indirect case
5794 -- Who knows what happens when another task is activated?
5796 Kill_Current_Values;
5799 -- Normal subprogram call with name established in Resolve
5805 -- Otherwise we must have the case of an overloaded call
5807 else
5810 -- Initialize Nam to prevent warning (we know it will be assigned
5811 -- in the loop below, but the compiler does not know that).
5831 then
5832 -- The prefix is a parameterless function call that returns an access
5833 -- to subprogram. If parameters are present in the current call, add
5834 -- add an explicit dereference. We use the base type here because
5835 -- within an instance these may be subtypes.
5837 -- The dereference is added either in Analyze_Call or here. Should
5838 -- be consolidated ???
5847 -- Check that a call to Current_Task does not occur in an entry body
5850 declare
5853 begin
5855 loop
5858 -- Exclude calls that occur within the default of a formal
5859 -- parameter of the entry, since those are evaluated outside
5860 -- of the body.
5867 then
5870 Error_Msg_NE
5884 -- Check that a procedure call does not occur in the context of the
5885 -- entry call statement of a conditional or timed entry call. Note that
5886 -- the case of a call to a subprogram renaming of an entry will also be
5887 -- rejected. The test for N not being an N_Entry_Call_Statement is
5888 -- defensive, covering the possibility that the processing of entry
5889 -- calls might reach this point due to later modifications of the code
5890 -- above.
5895 then
5899 -- Ada 2005 (AI-345): If a procedure_call_statement is used
5900 -- for a procedure_or_entry_call, the procedure_name or
5901 -- procedure_prefix of the procedure_call_statement shall denote
5902 -- an entry renamed by a procedure, or (a view of) a primitive
5903 -- subprogram of a limited interface whose first parameter is
5904 -- a controlling parameter.
5909 then
5910 Error_Msg_N
5915 -- If the SPARK_05 restriction is active, we are not allowed
5916 -- to have a call to a subprogram before we see its completion.
5921 -- Don't flag strange internal calls
5926 -- Only flag calls in extended main source
5931 -- Exclude enumeration literals from this processing
5934 then
5935 Check_SPARK_05_Restriction
5939 -- Check that this is not a call to a protected procedure or entry from
5940 -- within a protected function.
5944 -- Freeze the subprogram name if not in a spec-expression. Note that
5945 -- we freeze procedure calls as well as function calls. Procedure calls
5946 -- are not frozen according to the rules (RM 13.14(14)) because it is
5947 -- impossible to have a procedure call to a non-frozen procedure in
5948 -- pure Ada, but in the code that we generate in the expander, this
5949 -- rule needs extending because we can generate procedure calls that
5950 -- need freezing.
5952 -- In Ada 2012, expression functions may be called within pre/post
5953 -- conditions of subsequent functions or expression functions. Such
5954 -- calls do not freeze when they appear within generated bodies,
5955 -- (including the body of another expression function) which would
5956 -- place the freeze node in the wrong scope. An expression function
5957 -- is frozen in the usual fashion, by the appearance of a real body,
5958 -- or at the end of a declarative part.
5961 and then not In_Spec_Expression
5963 and then
5966 then
5970 -- For a predefined operator, the type of the result is the type imposed
5971 -- by context, except for a predefined operation on universal fixed.
5972 -- Otherwise The type of the call is the type returned by the subprogram
5973 -- being called.
5980 -- If the subprogram returns an array type, and the context requires the
5981 -- component type of that array type, the node is really an indexing of
5982 -- the parameterless call. Resolve as such. A pathological case occurs
5983 -- when the type of the component is an access to the array type. In
5984 -- this case the call is truly ambiguous. If the call is to an intrinsic
5985 -- subprogram, it can't be an indexed component. This check is necessary
5986 -- because if it's Unchecked_Conversion, and we have "type T_Ptr is
5987 -- access T;" and "type T is array (...) of T_Ptr;" (i.e. an array of
5988 -- pointers to the same array), the compiler gets confused and does an
5989 -- infinite recursion.
5992 and then
5995 or else
5998 and then
6001 then
6002 declare
6007 begin
6010 then
6011 Error_Msg_N
6013 else
6016 -- The called entity may be an explicit dereference, in which
6017 -- case there is no entity to set.
6025 or else
6027 and then
6029 then
6032 -- Indexed call to a parameterless function
6034 Index_Node :=
6036 Prefix =>
6039 else
6040 -- An Ada 2005 prefixed call to a primitive operation
6041 -- whose first parameter is the prefix. This prefix was
6042 -- prepended to the parameter list, which is actually a
6043 -- list of indexes. Remove the prefix in order to build
6044 -- the proper indexed component.
6046 Index_Node :=
6048 Prefix =>
6051 Parameter_Associations =>
6052 New_List
6057 -- Preserve the parenthesis count of the node
6061 -- Since we are correcting a node classification error made
6062 -- by the parser, we call Replace rather than Rewrite.
6076 else
6077 -- If the called function is not declared in the main unit and it
6078 -- returns the limited view of type then use the available view (as
6079 -- is done in Try_Object_Operation) to prevent back-end confusion;
6080 -- the call must appear in a context where the nonlimited view is
6081 -- available. If the called function is in the extended main unit
6082 -- then no action is needed, because the back end handles this case.
6086 then
6093 -- In the case where the call is to an overloaded subprogram, Analyze
6094 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
6095 -- such a case Normalize_Actuals needs to be called once more to order
6096 -- the actuals correctly. Otherwise the call will have the ordering
6097 -- given by the last overloaded subprogram whether this is the correct
6098 -- one being called or not.
6105 -- In any case, call is fully resolved now. Reset Overload flag, to
6106 -- prevent subsequent overload resolution if node is analyzed again
6111 -- A Ghost entity must appear in a specific context
6117 -- If we are calling the current subprogram from immediately within its
6118 -- body, then that is the case where we can sometimes detect cases of
6119 -- infinite recursion statically. Do not try this in case restriction
6120 -- No_Recursion is in effect anyway, and do it only for source calls.
6125 -- Check violation of SPARK_05 restriction which does not permit
6126 -- a subprogram body to contain a call to the subprogram directly.
6130 then
6131 Check_SPARK_05_Restriction
6135 -- Issue warning for possible infinite recursion in the absence
6136 -- of the No_Recursion restriction.
6141 then
6142 -- Here we detected and flagged an infinite recursion, so we do
6143 -- not need to test the case below for further warnings. Also we
6144 -- are all done if we now have a raise SE node.
6150 -- If call is to immediately containing subprogram, then check for
6151 -- the case of a possible run-time detectable infinite recursion.
6153 else
6157 -- Although in general case, recursion is not statically
6158 -- checkable, the case of calling an immediately containing
6159 -- subprogram is easy to catch.
6163 -- If the recursive call is to a parameterless subprogram,
6164 -- then even if we can't statically detect infinite
6165 -- recursion, this is pretty suspicious, and we output a
6166 -- warning. Furthermore, we will try later to detect some
6167 -- cases here at run time by expanding checking code (see
6168 -- Detect_Infinite_Recursion in package Exp_Ch6).
6170 -- If the recursive call is within a handler, do not emit a
6171 -- warning, because this is a common idiom: loop until input
6172 -- is correct, catch illegal input in handler and restart.
6178 then
6179 -- For the case of a procedure call. We give the message
6180 -- only if the call is the first statement in a sequence
6181 -- of statements, or if all previous statements are
6182 -- simple assignments. This is simply a heuristic to
6183 -- decrease false positives, without losing too many good
6184 -- warnings. The idea is that these previous statements
6185 -- may affect global variables the procedure depends on.
6186 -- We also exclude raise statements, that may arise from
6187 -- constraint checks and are probably unrelated to the
6188 -- intended control flow.
6192 then
6193 declare
6195 begin
6199 N_Raise_Constraint_Error)
6200 then
6209 -- Do not give warning if we are in a conditional context
6211 declare
6213 begin
6219 then
6224 -- Here warning is to be issued
6240 -- Check obsolescent reference to Ada.Characters.Handling subprogram
6244 -- If subprogram name is a predefined operator, it was given in
6245 -- functional notation. Replace call node with operator node, so
6246 -- that actuals can be resolved appropriately.
6254 then
6260 -- Create a transient scope if the resulting type requires it
6262 -- There are several notable exceptions:
6264 -- a) In init procs, the transient scope overhead is not needed, and is
6265 -- even incorrect when the call is a nested initialization call for a
6266 -- component whose expansion may generate adjust calls. However, if the
6267 -- call is some other procedure call within an initialization procedure
6268 -- (for example a call to Create_Task in the init_proc of the task
6269 -- run-time record) a transient scope must be created around this call.
6271 -- b) Enumeration literal pseudo-calls need no transient scope
6273 -- c) Intrinsic subprograms (Unchecked_Conversion and source info
6274 -- functions) do not use the secondary stack even though the return
6275 -- type may be unconstrained.
6277 -- d) Calls to a build-in-place function, since such functions may
6278 -- allocate their result directly in a target object, and cases where
6279 -- the result does get allocated in the secondary stack are checked for
6280 -- within the specialized Exp_Ch6 procedures for expanding those
6281 -- build-in-place calls.
6283 -- e) Calls to inlinable expression functions do not use the secondary
6284 -- stack (since the call will be replaced by its returned object).
6286 -- f) If the subprogram is marked Inline_Always, then even if it returns
6287 -- an unconstrained type the call does not require use of the secondary
6288 -- stack. However, inlining will only take place if the body to inline
6289 -- is already present. It may not be available if e.g. the subprogram is
6290 -- declared in a child instance.
6292 -- If this is an initialization call for a type whose construction
6293 -- uses the secondary stack, and it is not a nested call to initialize
6294 -- a component, we do need to create a transient scope for it. We
6295 -- check for this by traversing the type in Check_Initialization_Call.
6301 then
6308 then
6311 elsif Expander_Active
6314 and then
6316 or else
6318 then
6321 -- If the call appears within the bounds of a loop, it will
6322 -- be rewritten and reanalyzed, nothing left to do here.
6329 and then not Within_Init_Proc
6330 then
6334 -- A protected function cannot be called within the definition of the
6335 -- enclosing protected type, unless it is part of a pre/postcondition
6336 -- on another protected operation. This may appear in the entry wrapper
6337 -- created for an entry with preconditions.
6342 and then not In_Spec_Expression
6344 then
6345 Error_Msg_NE
6349 -- Propagate interpretation to actuals, and add default expressions
6350 -- where needed.
6355 -- Overloaded literals are rewritten as function calls, for purpose of
6356 -- resolution. After resolution, we can replace the call with the
6357 -- literal itself.
6363 -- Avoid validation, since it is a static function call
6369 -- If the subprogram is not global, then kill all saved values and
6370 -- checks. This is a bit conservative, since in many cases we could do
6371 -- better, but it is not worth the effort. Similarly, we kill constant
6372 -- values. However we do not need to do this for internal entities
6373 -- (unless they are inherited user-defined subprograms), since they
6374 -- are not in the business of molesting local values.
6376 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
6377 -- kill all checks and values for calls to global subprograms. This
6378 -- takes care of the case where an access to a local subprogram is
6379 -- taken, and could be passed directly or indirectly and then called
6380 -- from almost any context.
6382 -- Note: we do not do this step till after resolving the actuals. That
6383 -- way we still take advantage of the current value information while
6384 -- scanning the actuals.
6386 -- We suppress killing values if we are processing the nodes associated
6387 -- with N_Freeze_Entity nodes. Otherwise the declaration of a tagged
6388 -- type kills all the values as part of analyzing the code that
6389 -- initializes the dispatch tables.
6393 or else Suppress_Value_Tracking_On_Call
6398 then
6399 Kill_Current_Values;
6402 -- If we are warning about unread OUT parameters, this is the place to
6403 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
6404 -- after the above call to Kill_Current_Values (since that call clears
6405 -- the Last_Assignment field of all local variables).
6410 then
6411 declare
6415 begin
6425 then
6435 -- If the subprogram is a primitive operation, check whether or not
6436 -- it is a correct dispatching call.
6440 then
6445 and then not In_Instance
6446 then
6450 -- If this is a dispatching call, generate the appropriate reference,
6451 -- for better source navigation in GPS.
6455 then
6458 -- Normal case, not a dispatching call: generate a call reference
6460 else
6468 -- Check for violation of restriction No_Specific_Termination_Handlers
6469 -- and warn on a potentially blocking call to Abort_Task.
6473 or else
6475 then
6482 -- A call to Ada.Real_Time.Timing_Events.Set_Handler to set a relative
6483 -- timing event violates restriction No_Relative_Delay (AI-0211). We
6484 -- need to check the second argument to determine whether it is an
6485 -- absolute or relative timing event.
6490 then
6494 -- Issue an error for a call to an eliminated subprogram. This routine
6495 -- will not perform the check if the call appears within a default
6496 -- expression.
6500 -- In formal mode, the primitive operations of a tagged type or type
6501 -- extension do not include functions that return the tagged type.
6507 then
6511 -- Implement rule in 12.5.1 (23.3/2): In an instance, if the actual is
6512 -- class-wide and the call dispatches on result in a context that does
6513 -- not provide a tag, the call raises Program_Error.
6516 and then In_Instance
6521 then
6522 -- Verify that none of the formals are controlling
6524 declare
6528 begin
6550 -- Check for calling a function with OUT or IN OUT parameter when the
6551 -- calling context (us right now) is not Ada 2012, so does not allow
6552 -- OUT or IN OUT parameters in function calls. Functions declared in
6553 -- a predefined unit are OK, as they may be called indirectly from a
6554 -- user-declared instantiation.
6560 then
6565 -- Check the dimensions of the actuals in the call. For function calls,
6566 -- propagate the dimensions from the returned type to N.
6570 -- All done, evaluate call and deal with elaboration issues
6575 -- In GNATprove mode, expansion is disabled, but we want to inline some
6576 -- subprograms to facilitate formal verification. Indirect calls through
6577 -- a subprogram type or within a generic cannot be inlined. Inlining is
6578 -- performed only for calls subject to SPARK_Mode on.
6580 if GNATprove_Mode
6583 and then not Inside_A_Generic
6584 then
6591 -- Nothing to do if the subprogram is not eligible for inlining in
6592 -- GNATprove mode.
6596 then
6599 -- Calls cannot be inlined inside assertions, as GNATprove treats
6600 -- assertions as logic expressions.
6603 Cannot_Inline
6606 -- Calls cannot be inlined inside default expressions
6609 Cannot_Inline
6612 -- Inlining should not be performed during pre-analysis
6616 -- With the one-pass inlining technique, a call cannot be
6617 -- inlined if the corresponding body has not been seen yet.
6620 Cannot_Inline
6623 -- Nothing to do if there is no body to inline, indicating that
6624 -- the subprogram is not suitable for inlining in GNATprove
6625 -- mode.
6630 -- Do not inline calls inside expression functions, as this
6631 -- would prevent interpreting them as logical formulas in
6632 -- GNATprove.
6635 and then
6637 then
6638 Cannot_Inline
6642 -- Calls cannot be inlined inside potentially unevaluated
6643 -- expressions, as this would create complex actions inside
6644 -- expressions, that are not handled by GNATprove.
6647 Cannot_Inline
6651 -- Do not inline calls which would possibly lead to missing a
6652 -- type conversion check on an input parameter.
6655 Cannot_Inline
6659 -- Otherwise, inline the call
6661 else
6671 -----------------------------
6672 -- Resolve_Case_Expression --
6673 -----------------------------
6681 begin
6688 -- When the expression is of a scalar subtype different from the
6689 -- result subtype, then insert a conversion to ensure the generation
6690 -- of a constraint check.
6700 -- Apply RM 4.5.7 (17/3): whether the expression is statically or
6701 -- dynamically tagged must be known statically.
6709 Error_Msg_N
6722 -------------------------------
6723 -- Resolve_Character_Literal --
6724 -------------------------------
6730 begin
6731 -- Verify that the character does belong to the type of the context
6736 -- Wide_Wide_Character literals must always be defined, since the set
6737 -- of wide wide character literals is complete, i.e. if a character
6738 -- literal is accepted by the parser, then it is OK for wide wide
6739 -- character (out of range character literals are rejected).
6744 -- Always accept character literal for type Any_Character, which
6745 -- occurs in error situations and in comparisons of literals, both
6746 -- of which should accept all literals.
6751 -- For Standard.Character or a type derived from it, check that the
6752 -- literal is in range.
6759 -- For Standard.Wide_Character or a type derived from it, check that the
6760 -- literal is in range.
6767 -- For Standard.Wide_Wide_Character or a type derived from it, we
6768 -- know the literal is in range, since the parser checked.
6773 -- If the entity is already set, this has already been resolved in a
6774 -- generic context, or comes from expansion. Nothing else to do.
6779 -- Otherwise we have a user defined character type, and we can use the
6780 -- standard visibility mechanisms to locate the referenced entity.
6782 else
6795 -- If we fall through, then the literal does not match any of the
6796 -- entries of the enumeration type. This isn't just a constraint error
6797 -- situation, it is an illegality (see RM 4.2).
6799 Error_Msg_NE
6803 ---------------------------
6804 -- Resolve_Comparison_Op --
6805 ---------------------------
6807 -- Context requires a boolean type, and plays no role in resolution.
6808 -- Processing identical to that for equality operators. The result type is
6809 -- the base type, which matters when pathological subtypes of booleans with
6810 -- limited ranges are used.
6817 begin
6818 -- If this is an intrinsic operation which is not predefined, use the
6819 -- types of its declared arguments to resolve the possibly overloaded
6820 -- operands. Otherwise the operands are unambiguous and specify the
6821 -- expected type.
6826 else
6837 -- Skip remaining processing if already set to Any_Type
6843 -- Deal with other error cases
6847 T = Any_Character
6848 then
6851 else
6859 -- Resolve the operands if types OK
6868 -- In SPARK, ordering operators <, <=, >, >= are not defined for Boolean
6869 -- types or array types except String.
6872 Check_SPARK_05_Restriction
6877 then
6878 Check_SPARK_05_Restriction
6882 -- Check comparison on unordered enumeration
6886 Error_Msg_NE
6891 -- Evaluate the relation (note we do this after the above check since
6892 -- this Eval call may change N to True/False.
6898 -----------------------------------------
6899 -- Resolve_Discrete_Subtype_Indication --
6900 -----------------------------------------
6902 procedure Resolve_Discrete_Subtype_Indication
6905 is
6909 begin
6917 else
6927 Error_Msg_NE
6930 -- Rewrite the constraint as a range of Typ
6931 -- to allow compilation to proceed further.
6943 else
6947 -- Additionally, we must check that the bounds are compatible
6948 -- with the given subtype, which might be different from the
6949 -- type of the context.
6953 -- ??? If the above check statically detects a Constraint_Error
6954 -- it replaces the offending bound(s) of the range R with a
6955 -- Constraint_Error node. When the itype which uses these bounds
6956 -- is frozen the resulting call to Duplicate_Subexpr generates
6957 -- a new temporary for the bounds.
6959 -- Unfortunately there are other itypes that are also made depend
6960 -- on these bounds, so when Duplicate_Subexpr is called they get
6961 -- a forward reference to the newly created temporaries and Gigi
6962 -- aborts on such forward references. This is probably sign of a
6963 -- more fundamental problem somewhere else in either the order of
6964 -- itype freezing or the way certain itypes are constructed.
6966 -- To get around this problem we call Remove_Side_Effects right
6967 -- away if either bounds of R are a Constraint_Error.
6969 declare
6973 begin
6989 -------------------------
6990 -- Resolve_Entity_Name --
6991 -------------------------
6993 -- Used to resolve identifiers and expanded names
6996 function Is_Assignment_Or_Object_Expression
6999 -- Determine whether node Context denotes an assignment statement or an
7000 -- object declaration whose expression is node Expr.
7002 ----------------------------------------
7003 -- Is_Assignment_Or_Object_Expression --
7004 ----------------------------------------
7006 function Is_Assignment_Or_Object_Expression
7009 is
7010 begin
7012 N_Object_Declaration)
7014 then
7017 -- Check whether a construct that yields a name is the expression of
7018 -- an assignment statement or an object declaration.
7021 N_Explicit_Dereference,
7022 N_Indexed_Component,
7023 N_Selected_Component,
7024 N_Slice)
7026 or else
7028 N_Unchecked_Type_Conversion)
7030 then
7031 return
7032 Is_Assignment_Or_Object_Expression
7036 -- Otherwise the context is not an assignment statement or an object
7037 -- declaration.
7039 else
7044 -- Local variables
7049 -- Start of processing for Resolve_Entity_Name
7051 begin
7052 -- If garbage from errors, set to Any_Type and return
7059 -- Replace named numbers by corresponding literals. Note that this is
7060 -- the one case where Resolve_Entity_Name must reset the Etype, since
7061 -- it is currently marked as universal.
7071 -- For enumeration literals, we need to make sure that a proper style
7072 -- check is done, since such literals are overloaded, and thus we did
7073 -- not do a style check during the first phase of analysis.
7079 -- Case of (sub)type name appearing in a context where an expression
7080 -- is expected. This is legal if occurrence is a current instance.
7081 -- See RM 8.6 (17/3).
7087 -- Any other use is an error
7089 else
7090 Error_Msg_N
7094 -- Check discriminant use if entity is discriminant in current scope,
7095 -- i.e. discriminant of record or concurrent type currently being
7096 -- analyzed. Uses in corresponding body are unrestricted.
7101 then
7104 -- A parameterless generic function cannot appear in a context that
7105 -- requires resolution.
7110 -- In Ada 83 an OUT parameter cannot be read
7115 or else Is_Assignment_Or_Object_Expression
7118 then
7123 -- In all other cases, just do the possible static evaluation
7125 else
7126 -- A deferred constant that appears in an expression must have a
7127 -- completion, unless it has been removed by in-place expansion of
7128 -- an aggregate. A constant that is a renaming does not need
7129 -- initialization.
7135 and then not In_Spec_Expression
7138 then
7142 then
7144 else
7145 Error_Msg_N
7155 -- When the entity appears in a parameter association, retrieve the
7156 -- related subprogram call.
7164 -- The following checks are only relevant when SPARK_Mode is on as
7165 -- they are not standard Ada legality rules.
7169 -- An effectively volatile object subject to enabled properties
7170 -- Async_Writers or Effective_Reads must appear in non-interfering
7171 -- context (SPARK RM 7.1.3(12)).
7178 then
7179 SPARK_Msg_N
7184 -- Check for possible elaboration issues with respect to reads of
7185 -- variables. The act of renaming the variable is not considered a
7186 -- read as it simply establishes an alias.
7189 and then Dynamic_Elaboration_Checks
7191 then
7195 -- The variable may eventually become a constituent of a single
7196 -- protected/task type. Record the reference now and verify its
7197 -- legality when analyzing the contract of the variable
7198 -- (SPARK RM 9.3).
7205 -- A Ghost entity must appear in a specific context
7213 -------------------
7214 -- Resolve_Entry --
7215 -------------------
7227 -- If the bounds of the entry family being called depend on task
7228 -- discriminants, build a new index subtype where a discriminant is
7229 -- replaced with the value of the discriminant of the target task.
7230 -- The target task is the prefix of the entry name in the call.
7232 -----------------------
7233 -- Actual_Index_Type --
7234 -----------------------
7244 -- If the bound is given by a discriminant, replace with a reference
7245 -- to the discriminant of the same name in the target task. If the
7246 -- entry name is the target of a requeue statement and the entry is
7247 -- in the current protected object, the bound to be used is the
7248 -- discriminal of the object (see Apply_Range_Checks for details of
7249 -- the transformation).
7251 -----------------------------
7252 -- Actual_Discriminant_Ref --
7253 -----------------------------
7259 begin
7264 then
7270 then
7271 -- Note: here Bound denotes a discriminant of the corresponding
7272 -- record type tskV, whose discriminal is a formal of the
7273 -- init-proc tskVIP. What we want is the body discriminal,
7274 -- which is associated to the discriminant of the original
7275 -- concurrent type tsk.
7277 return New_Occurrence_Of
7280 else
7281 Ref :=
7291 -- Start of processing for Actual_Index_Type
7293 begin
7296 then
7299 else
7313 -- Start of processing for Resolve_Entry
7315 begin
7316 -- Find name of entry being called, and resolve prefix of name with its
7317 -- own type. The prefix can be overloaded, and the name and signature of
7318 -- the entry must be taken into account.
7322 -- Case of dealing with entry family within the current tasks
7326 else
7332 -- Entry call to an entry (or entry family) in the current task. This
7333 -- is legal even though the task will deadlock. Rewrite as call to
7334 -- current task.
7336 -- This can also be a call to an entry in an enclosing task. If this
7337 -- is a single task, we have to retrieve its name, because the scope
7338 -- of the entry is the task type, not the object. If the enclosing
7339 -- task is a task type, the identity of the task is given by its own
7340 -- self variable.
7342 -- Finally this can be a requeue on an entry of the same task or
7343 -- protected object.
7350 then
7351 -- S is an enclosing task or protected object. The concurrent
7352 -- declaration has been converted into a type declaration, and
7353 -- the object itself has an object declaration that follows
7354 -- the type in the same declarative part.
7366 -- Call to current task. Will be transformed into call to Self
7373 New_N :=
7376 Selector_Name =>
7383 then
7384 -- Use the entry name (which must be unique at this point) to find
7385 -- the prefix that returns the corresponding task/protected type.
7387 declare
7393 begin
7415 -- Up to this point the expression could have been the actual in a
7416 -- simple entry call, and be given by a named association.
7420 else
7426 ------------------------
7427 -- Resolve_Entry_Call --
7428 ------------------------
7440 begin
7441 -- We kill all checks here, because it does not seem worth the effort to
7442 -- do anything better, an entry call is a big operation.
7444 Kill_All_Checks;
7446 -- Processing of the name is similar for entry calls and protected
7447 -- operation calls. Once the entity is determined, we can complete
7448 -- the resolution of the actuals.
7450 -- The selector may be overloaded, in the case of a protected object
7451 -- with overloaded functions. The type of the context is used for
7452 -- resolution.
7457 then
7458 declare
7462 begin
7481 -- Simple entry call
7489 -- Call to member of entry family
7496 -- We cannot in general check the maximum depth of protected entry calls
7497 -- at compile time. But we can tell that any protected entry call at all
7498 -- violates a specified nesting depth of zero.
7504 -- Use context type to disambiguate a protected function that can be
7505 -- called without actuals and that returns an array type, and where the
7506 -- argument list may be an indexing of the returned value.
7511 and then
7517 and then
7518 Covers
7521 then
7522 declare
7525 begin
7526 Index_Node :=
7528 Prefix =>
7532 -- Since we are correcting a node classification error made by the
7533 -- parser, we call Replace rather than Rewrite.
7546 then
7548 -- Note the entity being called before rewriting the call, so that
7549 -- it appears used at this point.
7553 -- Rewrite as call to the precondition wrapper, adding the task
7554 -- object to the list of actuals. If the call is to a member of an
7555 -- entry family, include the index as well.
7557 declare
7561 begin
7570 New_Call :=
7572 Name =>
7577 -- Preanalyze and resolve new call. Current procedure is called
7578 -- from Resolve_Call, after which expansion will take place.
7585 -- The operation name may have been overloaded. Order the actuals
7586 -- according to the formals of the resolved entity, and set the return
7587 -- type to that of the operation.
7594 -- Reset the Is_Overloaded flag, since resolution is now completed
7596 -- Simple entry call
7601 -- Call to a member of an entry family
7611 -- Create a call reference to the entry
7619 -- Verify that a procedure call cannot masquerade as an entry
7620 -- call where an entry call is expected.
7625 then
7630 then
7635 then
7640 -- After resolution, entry calls and protected procedure calls are
7641 -- changed into entry calls, for expansion. The structure of the node
7642 -- does not change, so it can safely be done in place. Protected
7643 -- function calls must keep their structure because they are
7644 -- subexpressions.
7648 -- A protected operation that is not a function may modify the
7649 -- corresponding object, and cannot apply to a constant. If this
7650 -- is an internal call, the prefix is the type itself.
7656 then
7657 Error_Msg_N
7659 Entry_Name);
7673 -- Protected functions can return on the secondary stack, in which
7674 -- case we must trigger the transient scope mechanism.
7676 elsif Expander_Active
7678 then
7683 -------------------------
7684 -- Resolve_Equality_Op --
7685 -------------------------
7687 -- Both arguments must have the same type, and the boolean context does
7688 -- not participate in the resolution. The first pass verifies that the
7689 -- interpretation is not ambiguous, and the type of the left argument is
7690 -- correctly set, or is Any_Type in case of ambiguity. If both arguments
7691 -- are strings or aggregates, allocators, or Null, they are ambiguous even
7692 -- though they carry a single (universal) type. Diagnose this case here.
7700 -- The resolution rule for if expressions requires that each such must
7701 -- have a unique type. This means that if several dependent expressions
7702 -- are of a non-null anonymous access type, and the context does not
7703 -- impose an expected type (as can be the case in an equality operation)
7704 -- the expression must be rejected.
7707 -- Attempt to explain the nature of a redundant comparison with True. If
7708 -- the expression N is too complex, this routine issues a general error
7709 -- message.
7712 -- In the case of allocators and access attributes, the context must
7713 -- provide an indication of the specific access type to be used. If
7714 -- one operand is of such a "generic" access type, check whether there
7715 -- is a specific visible access type that has the same designated type.
7716 -- This is semantically dubious, and of no interest to any real code,
7717 -- but c48008a makes it all worthwhile.
7719 -------------------------
7720 -- Check_If_Expression --
7721 -------------------------
7727 begin
7734 then
7740 ------------------------
7741 -- Explain_Redundancy --
7742 ------------------------
7749 begin
7752 -- Strip the operand down to an entity
7754 loop
7757 else
7762 -- The construct denotes an entity
7767 -- Do not generate an error message when the comparison is done
7768 -- against the enumeration literal Standard.True.
7772 -- Build a customized error message
7799 -- The construct is too complex to disect, issue a general message
7801 else
7806 -----------------------------
7807 -- Find_Unique_Access_Type --
7808 -----------------------------
7815 begin
7817 E_Access_Attribute_Type)
7818 then
7822 E_Access_Attribute_Type)
7823 then
7825 else
7837 then
7850 -- Start of processing for Resolve_Equality_Op
7852 begin
7863 T = Any_Character
7864 then
7867 else
7876 then
7885 -- If expressions must have a single type, and if the context does
7886 -- not impose one the dependent expressions cannot be anonymous
7887 -- access types.
7889 -- Why no similar processing for case expressions???
7893 E_Anonymous_Access_Subprogram_Type)
7895 E_Anonymous_Access_Subprogram_Type)
7896 then
7904 -- In SPARK, equality operators = and /= for array types other than
7905 -- String are only defined when, for each index position, the
7906 -- operands have equal static bounds.
7910 -- Protect call to Matching_Static_Array_Bounds to avoid costly
7911 -- operation if not needed.
7919 then
7920 Check_SPARK_05_Restriction
7925 -- If the unique type is a class-wide type then it will be expanded
7926 -- into a dispatching call to the predefined primitive. Therefore we
7927 -- check here for potential violation of such restriction.
7933 if Warn_On_Redundant_Constructs
7938 then
7939 Error_Msg_N -- CODEFIX
7949 -- If this is an inequality, it may be the implicit inequality
7950 -- created for a user-defined operation, in which case the corres-
7951 -- ponding equality operation is not intrinsic, and the operation
7952 -- cannot be constant-folded. Else fold.
7957 or else Is_Intrinsic_Subprogram
7959 then
7965 then
7969 -- Ada 2005: If one operand is an anonymous access type, convert the
7970 -- other operand to it, to ensure that the underlying types match in
7971 -- the back-end. Same for access_to_subprogram, and the conversion
7972 -- verifies that the types are subtype conformant.
7974 -- We apply the same conversion in the case one of the operands is a
7975 -- private subtype of the type of the other.
7977 -- Why the Expander_Active test here ???
7979 if Expander_Active
7980 and then
7982 E_Anonymous_Access_Subprogram_Type)
7984 then
8004 ----------------------------------
8005 -- Resolve_Explicit_Dereference --
8006 ----------------------------------
8014 -- The candidate prefix type, if overloaded
8019 begin
8023 -- A useful optimization: check whether the dereference denotes an
8024 -- element of a container, and if so rewrite it as a call to the
8025 -- corresponding Element function.
8027 -- Disabled for now, on advice of ARG. A more restricted form of the
8028 -- predicate might be acceptable ???
8030 -- if Is_Container_Element (N) then
8031 -- return;
8032 -- end if;
8036 -- Use the context type to select the prefix that has the correct
8037 -- designated type. Keep the first match, which will be the inner-
8038 -- most.
8045 then
8050 -- Remove access types that do not match, but preserve access
8051 -- to subprogram interpretations, in case a further dereference
8052 -- is needed (see below).
8065 else
8066 -- If no interpretation covers the designated type of the prefix,
8067 -- this is the pathological case where not all implementations of
8068 -- the prefix allow the interpretation of the node as a call. Now
8069 -- that the expected type is known, Remove other interpretations
8070 -- from prefix, rewrite it as a call, and resolve again, so that
8071 -- the proper call node is generated.
8082 New_N :=
8084 Name =>
8095 -- If not overloaded, resolve P with its own type
8097 else
8101 -- If the prefix might be null, add an access check
8105 then
8109 -- If the designated type is a packed unconstrained array type, and the
8110 -- explicit dereference is not in the context of an attribute reference,
8111 -- then we must compute and set the actual subtype, since it is needed
8112 -- by Gigi. The reason we exclude the attribute case is that this is
8113 -- handled fine by Gigi, and in fact we use such attributes to build the
8114 -- actual subtype. We also exclude generated code (which builds actual
8115 -- subtypes directly if they are needed).
8122 then
8128 -- Note: No Eval processing is required for an explicit dereference,
8129 -- because such a name can never be static.
8133 -------------------------------------
8134 -- Resolve_Expression_With_Actions --
8135 -------------------------------------
8138 begin
8141 -- If N has no actions, and its expression has been constant folded,
8142 -- then rewrite N as just its expression. Note, we can't do this in
8143 -- the general case of Is_Empty_List (Actions (N)) as this would cause
8144 -- Expression (N) to be expanded again.
8148 then
8153 ----------------------------------
8154 -- Resolve_Generalized_Indexing --
8155 ----------------------------------
8163 begin
8164 -- In ASIS mode, propagate the information about the indexes back to
8165 -- to the original indexing node. The generalized indexing is either
8166 -- a function call, or a dereference of one. The actuals include the
8167 -- prefix of the original node, which is the container expression.
8176 loop
8185 -- If expression is to be reanalyzed, reset Generalized_Indexing
8186 -- to recreate call node, as is the case when the expression is
8187 -- part of an expression function.
8196 else
8202 ---------------------------
8203 -- Resolve_If_Expression --
8204 ---------------------------
8213 begin
8218 -- When the "then" expression is of a scalar subtype different from the
8219 -- result subtype, then insert a conversion to ensure the generation of
8220 -- a constraint check. The same is done for the else part below, again
8221 -- comparing subtypes rather than base types.
8225 then
8230 -- If ELSE expression present, just resolve using the determined type
8231 -- If type is universal, resolve to any member of the class.
8240 else
8250 -- Apply RM 4.5.7 (17/3): whether the expression is statically or
8251 -- dynamically tagged must be known statically.
8256 then
8262 -- If no ELSE expression is present, root type must be Standard.Boolean
8263 -- and we provide a Standard.True result converted to the appropriate
8264 -- Boolean type (in case it is a derived boolean type).
8267 Else_Expr :=
8272 else
8281 -------------------------------
8282 -- Resolve_Indexed_Component --
8283 -------------------------------
8291 begin
8299 -- Use the context type to select the prefix that yields the correct
8300 -- component type.
8302 declare
8309 begin
8316 and then
8317 Covers
8320 then
8329 else
8335 else
8346 else
8353 -- If prefix is access type, dereference to get real array type.
8354 -- Note: we do not apply an access check because the expander always
8355 -- introduces an explicit dereference, and the check will happen there.
8361 -- If name was overloaded, set component type correctly now
8362 -- If a misplaced call to an entry family (which has no index types)
8363 -- return. Error will be diagnosed from calling context.
8367 else
8374 -- The prefix may have resolved to a string literal, in which case its
8375 -- etype has a special representation. This is only possible currently
8376 -- if the prefix is a static concatenation, written in functional
8377 -- notation.
8382 else
8389 else
8400 -- Do not generate the warning on suspicious index if we are analyzing
8401 -- package Ada.Tags; otherwise we will report the warning with the
8402 -- Prims_Ptr field of the dispatch table.
8405 or else not
8407 Ada_Tags)
8408 then
8413 -- If the array type is atomic, and the component is not atomic, then
8414 -- this is worth a warning, since we have a situation where the access
8415 -- to the component may cause extra read/writes of the atomic array
8416 -- object, or partial word accesses, which could be unexpected.
8422 and then Has_Atomic_Components
8425 then
8426 Error_Msg_N
8428 Error_Msg_N
8433 -----------------------------
8434 -- Resolve_Integer_Literal --
8435 -----------------------------
8438 begin
8443 --------------------------------
8444 -- Resolve_Intrinsic_Operator --
8445 --------------------------------
8454 -- If the operand is a literal, it cannot be the expression in a
8455 -- conversion. Use a qualified expression instead.
8457 ---------------------
8458 -- Convert_Operand --
8459 ---------------------
8465 begin
8467 Res :=
8473 else
8480 -- Start of processing for Resolve_Intrinsic_Operator
8482 begin
8483 -- We must preserve the original entity in a generic setting, so that
8484 -- the legality of the operation can be verified in an instance.
8499 -- If the result or operand types are private, rewrite with unchecked
8500 -- conversions on the operands and the result, to expose the proper
8501 -- underlying numeric type.
8506 then
8511 else
8532 then
8533 -- Add explicit conversion where needed, and save interpretations in
8534 -- case operands are overloaded.
8541 else
8547 else
8557 else
8562 --------------------------------------
8563 -- Resolve_Intrinsic_Unary_Operator --
8564 --------------------------------------
8566 procedure Resolve_Intrinsic_Unary_Operator
8569 is
8574 begin
8593 else
8598 ------------------------
8599 -- Resolve_Logical_Op --
8600 ------------------------
8605 begin
8608 -- Predefined operations on scalar types yield the base type. On the
8609 -- other hand, logical operations on arrays yield the type of the
8610 -- arguments (and the context).
8614 else
8618 -- The following test is required because the operands of the operation
8619 -- may be literals, in which case the resulting type appears to be
8620 -- compatible with a signed integer type, when in fact it is compatible
8621 -- only with modular types. If the context itself is universal, the
8622 -- operation is illegal.
8630 Error_Msg_N
8638 then
8642 -- Replace AND by AND THEN, or OR by OR ELSE, if Short_Circuit_And_Or
8643 -- is active and the result type is standard Boolean (do not mess with
8644 -- ops that return a nonstandard Boolean type, because something strange
8645 -- is going on).
8647 -- Note: you might expect this replacement to be done during expansion,
8648 -- but that doesn't work, because when the pragma Short_Circuit_And_Or
8649 -- is used, no part of the right operand of an "and" or "or" operator
8650 -- should be executed if the left operand would short-circuit the
8651 -- evaluation of the corresponding "and then" or "or else". If we left
8652 -- the replacement to expansion time, then run-time checks associated
8653 -- with such operands would be evaluated unconditionally, due to being
8654 -- before the condition prior to the rewriting as short-circuit forms
8655 -- during expansion.
8657 if Short_Circuit_And_Or
8660 then
8661 -- Mark the corresponding putative SCO operator as truly a logical
8662 -- (and short-circuit) operator.
8675 -- Case of OR changed to OR ELSE
8677 else
8685 -- Return now, since analysis of the rewritten ops will take care of
8686 -- other reference bookkeeping and expression folding.
8701 -- In SPARK, logical operations AND, OR and XOR for arrays are defined
8702 -- only when both operands have same static lower and higher bounds. Of
8703 -- course the types have to match, so only check if operands are
8704 -- compatible and the node itself has no errors.
8708 then
8709 declare
8713 begin
8714 -- Protect call to Matching_Static_Array_Bounds to avoid costly
8715 -- operation if not needed.
8722 then
8723 Check_SPARK_05_Restriction
8730 ---------------------------
8731 -- Resolve_Membership_Op --
8732 ---------------------------
8734 -- The context can only be a boolean type, and does not determine the
8735 -- arguments. Arguments should be unambiguous, but the preference rule for
8736 -- universal types applies.
8746 -- Analysis has determined a unique type for the left operand. Use it to
8747 -- resolve the disjuncts.
8749 ----------------------------
8750 -- Resolve_Set_Membership --
8751 ----------------------------
8757 begin
8758 -- If the left operand is overloaded, find type compatible with not
8759 -- overloaded alternative of the right operand.
8768 else
8773 -- Unclear how to resolve expression if all alternatives are also
8774 -- overloaded.
8780 else
8789 -- Alternative is an expression, a range
8790 -- or a subtype mark.
8794 then
8801 -- Check for duplicates for discrete case
8804 declare
8813 begin
8814 -- Loop checking duplicates. This is quadratic, but giant sets
8815 -- are unlikely in this context so it's a reasonable choice.
8822 N_Character_Literal)
8824 then
8842 -- Start of processing for Resolve_Membership_Op
8844 begin
8850 Resolve_Set_Membership;
8854 and then
8856 or else
8859 then
8862 -- Ada 2005 (AI-251): Support the following case:
8864 -- type I is interface;
8865 -- type T is tagged ...
8867 -- function Test (O : I'Class) is
8868 -- begin
8869 -- return O in T'Class.
8870 -- end Test;
8872 -- In this case we have nothing else to do. The membership test will be
8873 -- done at run time.
8880 then
8882 else
8886 -- If mixed-mode operations are present and operands are all literal,
8887 -- the only interpretation involves Duration, which is probably not
8888 -- the intention of the programmer.
8903 then
8909 else
8914 -- Here after resolving membership operation
8921 ------------------
8922 -- Resolve_Null --
8923 ------------------
8928 begin
8929 -- Handle restriction against anonymous null access values This
8930 -- restriction can be turned off using -gnatdj.
8932 -- Ada 2005 (AI-231): Remove restriction
8935 and then not Debug_Flag_J
8938 then
8939 -- In the common case of a call which uses an explicitly null value
8940 -- for an access parameter, give specialized error message.
8943 Error_Msg_N
8946 -- Standard message for all other cases (are there any?)
8948 else
8949 Error_Msg_N
8954 -- Ada 2005 (AI-231): Generate the null-excluding check in case of
8955 -- assignment to a null-excluding object
8960 then
8962 Insert_Action
8967 else
8974 -- In a distributed context, null for a remote access to subprogram may
8975 -- need to be replaced with a special record aggregate. In this case,
8976 -- return after having done the transformation.
8981 then
8985 -- The null literal takes its type from the context
8990 -----------------------
8991 -- Resolve_Op_Concat --
8992 -----------------------
8996 -- We wish to avoid deep recursion, because concatenations are often
8997 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
8998 -- operands nonrecursively until we find something that is not a simple
8999 -- concatenation (A in this case). We resolve that, and then walk back
9000 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
9001 -- to do the rest of the work at each level. The Parent pointers allow
9002 -- us to avoid recursion, and thus avoid running out of memory. See also
9003 -- Sem_Ch4.Analyze_Concatenation, where a similar approach is used.
9008 begin
9009 -- The following code is equivalent to:
9011 -- Resolve_Op_Concat_First (NN, Typ);
9012 -- Resolve_Op_Concat_Arg (N, ...);
9013 -- Resolve_Op_Concat_Rest (N, Typ);
9015 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
9016 -- operand is a concatenation.
9018 -- Walk down left operands
9020 loop
9029 -- Now (given the above example) NN is A&B and Op1 is A
9031 -- First resolve Op1 ...
9035 -- ... then walk NN back up until we reach N (where we started), calling
9036 -- Resolve_Op_Concat_Rest along the way.
9038 loop
9045 Check_SPARK_05_Restriction
9050 ---------------------------
9051 -- Resolve_Op_Concat_Arg --
9052 ---------------------------
9054 procedure Resolve_Op_Concat_Arg
9059 is
9063 begin
9065 if Is_Comp
9069 then
9071 else
9075 -- If both Array & Array and Array & Component are visible, there is a
9076 -- potential ambiguity that must be reported.
9081 then
9085 -- If the operation is user-defined and not overloaded use its
9086 -- profile. The operation may be a renaming, in which case it has
9087 -- been rewritten, and we want the original profile.
9092 then
9094 Etype
9098 -- Otherwise an aggregate may match both the array type and the
9099 -- component type.
9101 else
9106 else
9110 then
9111 declare
9116 begin
9121 -- Special-case the error message when the overloading is
9122 -- caused by a function that yields an array and can be
9123 -- called without parameters.
9128 Error_Msg_NE
9130 Error_Msg_NE
9134 else
9142 or else
9144 then
9145 Error_Msg_N -- CODEFIX
9163 else
9168 else
9172 -- Concatenation is restricted in SPARK: each operand must be either a
9173 -- string literal, the name of a string constant, a static character or
9174 -- string expression, or another concatenation. Arg cannot be a
9175 -- concatenation here as callers of Resolve_Op_Concat_Arg call it
9176 -- separately on each final operand, past concatenation operations.
9180 Check_SPARK_05_Restriction
9188 then
9189 Check_SPARK_05_Restriction
9193 -- Do not issue error on an operand that is neither a character nor a
9194 -- string, as the error is issued in Resolve_Op_Concat.
9196 else
9203 -----------------------------
9204 -- Resolve_Op_Concat_First --
9205 -----------------------------
9212 begin
9213 -- The parser folds an enormous sequence of concatenations of string
9214 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
9215 -- in the right operand. If the expression resolves to a predefined "&"
9216 -- operator, all is well. Otherwise, the parser's folding is wrong, so
9217 -- we give an error. See P_Simple_Expression in Par.Ch4.
9222 then
9237 ----------------------------
9238 -- Resolve_Op_Concat_Rest --
9239 ----------------------------
9245 begin
9254 -- If this is not a static concatenation, but the result is a string
9255 -- type (and not an array of strings) ensure that static string operands
9256 -- have their subtypes properly constructed.
9260 then
9266 ----------------------
9267 -- Resolve_Op_Expon --
9268 ----------------------
9273 begin
9274 -- Catch attempts to do fixed-point exponentiation with universal
9275 -- operands, which is a case where the illegality is not caught during
9276 -- normal operator analysis. This is not done in preanalysis mode
9277 -- since the tree is not fully decorated during preanalysis.
9288 then
9298 then
9305 then
9309 -- We do the resolution using the base type, because intermediate values
9310 -- in expressions are always of the base type, not a subtype of it.
9315 -- For integer types, right argument must be in Natural range
9330 -- Evaluate the exponentiation operator for dimensioned type
9333 else
9337 -- Set overflow checking bit. Much cleverer code needed here eventually
9338 -- and perhaps the Resolve routines should be separated for the various
9339 -- arithmetic operations, since they will need different processing. ???
9348 --------------------
9349 -- Resolve_Op_Not --
9350 --------------------
9356 -- This function determines if the parent node is a boolean operator or
9357 -- operation (comparison op, membership test, or short circuit form) and
9358 -- the not in question is the left operand of this operation. Note that
9359 -- if the not is in parens, then false is returned.
9361 -----------------------
9362 -- Parent_Is_Boolean --
9363 -----------------------
9366 begin
9370 else
9372 when N_And_Then
9373 | N_In
9374 | N_Not_In
9375 | N_Op_And
9376 | N_Op_Eq
9377 | N_Op_Ge
9378 | N_Op_Gt
9379 | N_Op_Le
9380 | N_Op_Lt
9381 | N_Op_Ne
9382 | N_Op_Or
9383 | N_Op_Xor
9384 | N_Or_Else
9385 =>
9394 -- Start of processing for Resolve_Op_Not
9396 begin
9397 -- Predefined operations on scalar types yield the base type. On the
9398 -- other hand, logical operations on arrays yield the type of the
9399 -- arguments (and the context).
9403 else
9407 -- Straightforward case of incorrect arguments
9414 -- Special case of probable missing parens
9418 Error_Msg_N
9421 else
9422 Error_Msg_N
9429 -- OK resolution of NOT
9431 else
9432 -- Warn if non-boolean types involved. This is a case like not a < b
9433 -- where a and b are modular, where we will get (not a) < b and most
9434 -- likely not (a < b) was intended.
9436 if Warn_On_Questionable_Missing_Parens
9438 and then Parent_Is_Boolean
9439 then
9443 -- Warn on double negation if checking redundant constructs
9445 if Warn_On_Redundant_Constructs
9450 then
9454 -- Complete resolution and evaluation of NOT
9464 -----------------------------
9465 -- Resolve_Operator_Symbol --
9466 -----------------------------
9468 -- Nothing to be done, all resolved already
9474 begin
9478 ----------------------------------
9479 -- Resolve_Qualified_Expression --
9480 ----------------------------------
9488 begin
9491 -- Protect call to Matching_Static_Array_Bounds to avoid costly
9492 -- operation if not needed.
9499 then
9500 Check_SPARK_05_Restriction
9504 -- A qualified expression requires an exact match of the type, class-
9505 -- wide matching is not allowed. However, if the qualifying type is
9506 -- specific and the expression has a class-wide type, it may still be
9507 -- okay, since it can be the result of the expansion of a call to a
9508 -- dispatching function, so we also have to check class-wideness of the
9509 -- type of the expression's original node.
9512 or else
9516 then
9520 -- If the target type is unconstrained, then we reset the type of the
9521 -- result from the type of the expression. For other cases, the actual
9522 -- subtype of the expression is the target type.
9526 then
9533 -- If we still have a qualified expression after the static evaluation,
9534 -- then apply a scalar range check if needed. The reason that we do this
9535 -- after the Eval call is that otherwise, the application of the range
9536 -- check may convert an illegal static expression and result in warning
9537 -- rather than giving an error (e.g Integer'(Integer'Last + 1)).
9543 -- Finally, check whether a predicate applies to the target type. This
9544 -- comes from AI12-0100. As for type conversions, check the enclosing
9545 -- context to prevent an infinite expansion.
9551 or else
9553 then
9556 -- In the case of a qualified expression in an allocator, the check
9557 -- is applied when expanding the allocator, so avoid redundant check.
9561 then
9567 ------------------------------
9568 -- Resolve_Raise_Expression --
9569 ------------------------------
9572 begin
9576 else
9581 -------------------
9582 -- Resolve_Range --
9583 -------------------
9590 -- Returns True if N is of the form X'First .. X'Last where X is the
9591 -- same entity for both attributes.
9593 --------------------
9594 -- First_Last_Ref --
9595 --------------------
9601 begin
9606 then
9607 declare
9610 begin
9614 then
9623 -- Start of processing for Resolve_Range
9625 begin
9628 -- The lower bound should be in Typ. The higher bound can be in Typ's
9629 -- base type if the range is null. It may still be invalid if it is
9630 -- higher than the lower bound. This is checked later in the context in
9631 -- which the range appears.
9636 -- Check for inappropriate range on unordered enumeration type
9640 -- Exclude X'First .. X'Last if X is the same entity for both
9642 and then not First_Last_Ref
9643 then
9645 Error_Msg_NE
9652 -- We have to check the bounds for being within the base range as
9653 -- required for a non-static context. Normally this is automatic and
9654 -- done as part of evaluating expressions, but the N_Range node is an
9655 -- exception, since in GNAT we consider this node to be a subexpression,
9656 -- even though in Ada it is not. The circuit in Sem_Eval could check for
9657 -- this, but that would put the test on the main evaluation path for
9658 -- expressions.
9663 -- Check for an ambiguous range over character literals. This will
9664 -- happen with a membership test involving only literals.
9672 -- If bounds are static, constant-fold them, so size computations are
9673 -- identical between front-end and back-end. Do not perform this
9674 -- transformation while analyzing generic units, as type information
9675 -- would be lost when reanalyzing the constant node in the instance.
9688 --------------------------
9689 -- Resolve_Real_Literal --
9690 --------------------------
9695 begin
9696 -- Special processing for fixed-point literals to make sure that the
9697 -- value is an exact multiple of small where this is required. We skip
9698 -- this for the universal real case, and also for generic types.
9704 then
9705 declare
9712 begin
9713 -- Case of literal is not an exact multiple of the Small
9717 -- For a source program literal for a decimal fixed-point type,
9718 -- this is statically illegal (RM 4.9(36)).
9723 then
9727 -- Generate a warning if literal from source
9730 and then Warn_On_Bad_Fixed_Value
9731 then
9732 Error_Msg_N
9734 N);
9737 -- Replace literal by a value that is the exact representation
9738 -- of a value of the type, i.e. a multiple of the small value,
9739 -- by truncation, since Machine_Rounds is false for all GNAT
9740 -- fixed-point types (RM 4.9(38)).
9750 -- In all cases, set the corresponding integer field
9756 -- Now replace the actual type by the expected type as usual
9762 -----------------------
9763 -- Resolve_Reference --
9764 -----------------------
9769 begin
9770 -- Replace general access with specific type
9778 -- If we are taking the reference of a volatile entity, then treat it as
9779 -- a potential modification of this entity. This is too conservative,
9780 -- but necessary because remove side effects can cause transformations
9781 -- of normal assignments into reference sequences that otherwise fail to
9782 -- notice the modification.
9789 --------------------------------
9790 -- Resolve_Selected_Component --
9791 --------------------------------
9806 -- Check whether this is the initialization of a component within an
9807 -- init proc (by assignment or call to another init proc). If true,
9808 -- there is no need for a discriminant check.
9810 --------------------
9811 -- Init_Component --
9812 --------------------
9815 begin
9816 return Inside_Init_Proc
9822 -- Start of processing for Resolve_Selected_Component
9824 begin
9827 -- Use the context type to select the prefix that has a selector
9828 -- of the correct name and type.
9836 else
9840 -- Locate selected component. For a private prefix the selector
9841 -- can denote a discriminant.
9845 -- The visible components of a class-wide type are those of
9846 -- the root type.
9856 then
9863 else
9867 Error_Msg_N
9872 else
9875 -- There may be an implicit dereference. Retrieve
9876 -- designated record type.
9880 else
9886 -- Resolution chooses the new interpretation.
9887 -- Find the component with the right name.
9892 loop
9909 -- There must be a legal interpretation at this point
9916 else
9917 -- Resolve prefix with its type
9922 -- Generate cross-reference. We needed to wait until full overloading
9923 -- resolution was complete to do this, since otherwise we can't tell if
9924 -- we are an lvalue or not.
9928 else
9932 -- If prefix is an access type, the node will be transformed into an
9933 -- explicit dereference during expansion. The type of the node is the
9934 -- designated type of that of the prefix.
9939 else
9943 -- Set flag for expander if discriminant check required on a component
9944 -- appearing within a variant.
9950 and then
9953 and then not Init_Component
9954 then
9962 -- If the prefix is a record conversion, this may be a renamed
9963 -- discriminant whose bounds differ from those of the original
9964 -- one, so we must ensure that a range check is performed.
9969 then
9973 -- Note: No Eval processing is required, because the prefix is of a
9974 -- record type, or protected type, and neither can possibly be static.
9976 -- If the record type is atomic, and the component is non-atomic, then
9977 -- this is worth a warning, since we have a situation where the access
9978 -- to the component may cause extra read/writes of the atomic array
9979 -- object, or partial word accesses, both of which may be unexpected.
9985 then
9986 Error_Msg_N
9989 Error_Msg_N
9997 -------------------
9998 -- Resolve_Shift --
9999 -------------------
10006 begin
10007 -- We do the resolution using the base type, because intermediate values
10008 -- in expressions always are of the base type, not a subtype of it.
10021 ---------------------------
10022 -- Resolve_Short_Circuit --
10023 ---------------------------
10030 begin
10031 -- Ensure all actions associated with the left operand (e.g.
10032 -- finalization of transient objects) are fully evaluated locally within
10033 -- an expression with actions. This is particularly helpful for coverage
10034 -- analysis. However this should not happen in generics or if option
10035 -- Minimize_Expression_With_Actions is set.
10038 declare
10040 begin
10048 -- Set Comes_From_Source on L to preserve warnings for unset
10049 -- reference.
10058 -- Check for issuing warning for always False assert/check, this happens
10059 -- when assertions are turned off, in which case the pragma Assert/Check
10060 -- was transformed into:
10062 -- if False and then <condition> then ...
10064 -- and we detect this pattern
10066 if Warn_On_Assertion_Failure
10073 then
10074 declare
10077 begin
10078 -- Special handling of Asssert pragma
10082 then
10083 declare
10085 Original_Node
10086 (Expression
10089 begin
10090 -- Don't warn if original condition is explicit False,
10091 -- since obviously the failure is expected in this case.
10095 then
10098 -- Issue warning. We do not want the deletion of the
10099 -- IF/AND-THEN to take this message with it. We achieve this
10100 -- by making sure that the expanded code points to the Sloc
10101 -- of the expression, not the original pragma.
10103 else
10104 -- Note: Use Error_Msg_F here rather than Error_Msg_N.
10105 -- The source location of the expression is not usually
10106 -- the best choice here. For example, it gets located on
10107 -- the last AND keyword in a chain of boolean expressiond
10108 -- AND'ed together. It is best to put the message on the
10109 -- first character of the assertion, which is the effect
10110 -- of the First_Node call here.
10112 Error_Msg_F
10114 Expression
10119 -- Similar processing for Check pragma
10123 then
10124 -- Don't want to warn if original condition is explicit False
10126 declare
10128 Original_Node
10129 (Expression
10131 begin
10134 then
10137 -- Post warning
10139 else
10140 -- Again use Error_Msg_F rather than Error_Msg_N, see
10141 -- comment above for an explanation of why we do this.
10143 Error_Msg_F
10145 Expression
10153 -- Continue with processing of short circuit
10162 -------------------
10163 -- Resolve_Slice --
10164 -------------------
10173 begin
10176 -- Use the context type to select the prefix that yields the correct
10177 -- array type.
10179 declare
10186 begin
10194 then
10202 else
10207 else
10218 else
10228 -- If the prefix is an access to an unconstrained array, we must use
10229 -- the actual subtype of the object to perform the index checks. The
10230 -- object denoted by the prefix is implicit in the node, so we build
10231 -- an explicit representation for it in order to compute the actual
10232 -- subtype.
10237 declare
10241 begin
10252 then
10255 -- If the name is a selected component that depends on discriminants,
10256 -- build an actual subtype for it. This can happen only when the name
10257 -- itself is overloaded; otherwise the actual subtype is created when
10258 -- the selected component is analyzed.
10261 and then Full_Analysis
10263 then
10264 declare
10267 begin
10272 -- Maybe this should just be "else", instead of checking for the
10273 -- specific case of slice??? This is needed for the case where the
10274 -- prefix is an Image attribute, which gets expanded to a slice, and so
10275 -- has a constrained subtype which we want to use for the slice range
10276 -- check applied below (the range check won't get done if the
10277 -- unconstrained subtype of the 'Image is used).
10283 -- Obtain the type of the array index
10287 else
10291 -- If name was overloaded, set slice type correctly now
10295 -- Handle the generation of a range check that compares the array index
10296 -- against the discrete_range. The check is not applied to internally
10297 -- built nodes associated with the expansion of dispatch tables. Check
10298 -- that Ada.Tags has already been loaded to avoid extra dependencies on
10299 -- the unit.
10301 if Tagged_Type_Expansion
10307 then
10310 -- The discrete_range is specified by a subtype indication. Create a
10311 -- shallow copy and inherit the type, parent and source location from
10312 -- the discrete_range. This ensures that the range check is inserted
10313 -- relative to the slice and that the runtime exception points to the
10314 -- proper construct.
10323 -- The discrete_range is a regular range. Resolve the bounds and remove
10324 -- their side effects.
10326 else
10343 -- Check bad use of type with predicates
10345 declare
10348 begin
10351 then
10353 else
10358 Bad_Predicated_Subtype_Use
10363 -- Otherwise here is where we check suspicious indexes
10374 ----------------------------
10375 -- Resolve_String_Literal --
10376 ----------------------------
10387 begin
10388 -- For a string appearing in a concatenation, defer creation of the
10389 -- string_literal_subtype until the end of the resolution of the
10390 -- concatenation, because the literal may be constant-folded away. This
10391 -- is a useful optimization for long concatenation expressions.
10393 -- If the string is an aggregate built for a single character (which
10394 -- happens in a non-static context) or a is null string to which special
10395 -- checks may apply, we build the subtype. Wide strings must also get a
10396 -- string subtype if they come from a one character aggregate. Strings
10397 -- generated by attributes might be static, but it is often hard to
10398 -- determine whether the enclosing context is static, so we generate
10399 -- subtypes for them as well, thus losing some rarer optimizations ???
10400 -- Same for strings that come from a static conversion.
10402 Need_Check :=
10411 -- If the resolving type is itself a string literal subtype, we can just
10412 -- reuse it, since there is no point in creating another.
10418 and then not Need_Check
10420 N_Attribute_Reference,
10421 N_Qualified_Expression,
10422 N_Type_Conversion)
10423 then
10426 -- Do not generate a string literal subtype for the default expression
10427 -- of a formal parameter in GNATprove mode. This is because the string
10428 -- subtype is associated with the freezing actions of the subprogram,
10429 -- however freezing is disabled in GNATprove mode and as a result the
10430 -- subtype is unavailable.
10432 elsif GNATprove_Mode
10434 then
10437 -- Otherwise we must create a string literal subtype. Note that the
10438 -- whole idea of string literal subtypes is simply to avoid the need
10439 -- for building a full fledged array subtype for each literal.
10441 else
10447 or else Need_Check
10448 then
10455 then
10461 -- The validity of a null string has been checked in the call to
10462 -- Eval_String_Literal.
10467 -- Always accept string literal with component type Any_Character, which
10468 -- occurs in error situations and in comparisons of literals, both of
10469 -- which should accept all literals.
10474 -- If the type is bit-packed, then we always transform the string
10475 -- literal into a full fledged aggregate.
10480 -- Deal with cases of Wide_Wide_String, Wide_String, and String
10482 else
10483 -- For Standard.Wide_Wide_String, or any other type whose component
10484 -- type is Standard.Wide_Wide_Character, we know that all the
10485 -- characters in the string must be acceptable, since the parser
10486 -- accepted the characters as valid character literals.
10491 -- For the case of Standard.String, or any other type whose component
10492 -- type is Standard.Character, we must make sure that there are no
10493 -- wide characters in the string, i.e. that it is entirely composed
10494 -- of characters in range of type Character.
10496 -- If the string literal is the result of a static concatenation, the
10497 -- test has already been performed on the components, and need not be
10498 -- repeated.
10502 then
10506 -- If we are out of range, post error. This is one of the
10507 -- very few places that we place the flag in the middle of
10508 -- a token, right under the offending wide character. Not
10509 -- quite clear if this is right wrt wide character encoding
10510 -- sequences, but it's only an error message.
10512 Error_Msg
10519 -- For the case of Standard.Wide_String, or any other type whose
10520 -- component type is Standard.Wide_Character, we must make sure that
10521 -- there are no wide characters in the string, i.e. that it is
10522 -- entirely composed of characters in range of type Wide_Character.
10524 -- If the string literal is the result of a static concatenation,
10525 -- the test has already been performed on the components, and need
10526 -- not be repeated.
10530 then
10534 -- If we are out of range, post error. This is one of the
10535 -- very few places that we place the flag in the middle of
10536 -- a token, right under the offending wide character.
10538 -- This is not quite right, because characters in general
10539 -- will take more than one character position ???
10541 Error_Msg
10548 -- If the root type is not a standard character, then we will convert
10549 -- the string into an aggregate and will let the aggregate code do
10550 -- the checking. Standard Wide_Wide_Character is also OK here.
10552 else
10556 -- See if the component type of the array corresponding to the string
10557 -- has compile time known bounds. If yes we can directly check
10558 -- whether the evaluation of the string will raise constraint error.
10559 -- Otherwise we need to transform the string literal into the
10560 -- corresponding character aggregate and let the aggregate code do
10561 -- the checking.
10565 -- Check for the case of full range, where we are definitely OK
10571 -- Here the range is not the complete base type range, so check
10573 declare
10581 begin
10584 then
10590 then
10591 Apply_Compile_Time_Constraint_Error
10593 CE_Range_Check_Failed,
10604 -- If we got here we meed to transform the string literal into the
10605 -- equivalent qualified positional array aggregate. This is rather
10606 -- heavy artillery for this situation, but it is hard work to avoid.
10608 declare
10613 begin
10614 -- Build the character literals, we give them source locations that
10615 -- correspond to the string positions, which is a bit tricky given
10616 -- the possible presence of wide character escape sequences.
10630 -- Should we have a call to Skip_Wide here ???
10632 -- ??? else
10633 -- Skip_Wide (P);
10641 Expression =>
10648 -------------------------
10649 -- Resolve_Target_Name --
10650 -------------------------
10653 begin
10657 -----------------------------
10658 -- Resolve_Type_Conversion --
10659 -----------------------------
10671 -- Set to False to suppress cases where we want to suppress the test
10672 -- for redundancy to avoid possible false positives on this warning.
10674 begin
10675 if not Conv_OK
10677 then
10681 -- If the Operand Etype is Universal_Fixed, then the conversion is
10682 -- never redundant. We need this check because by the time we have
10683 -- finished the rather complex transformation, the conversion looks
10684 -- redundant when it is not.
10689 -- If the operand is marked as Any_Fixed, then special processing is
10690 -- required. This is also a case where we suppress the test for a
10691 -- redundant conversion, since most certainly it is not redundant.
10696 -- Mixed-mode operation involving a literal. Context must be a fixed
10697 -- type which is applied to the literal subsequently.
10705 or else
10707 then
10708 -- Return if expression is ambiguous
10713 -- If nothing else, the available fixed type is Duration
10715 else
10719 -- Resolve the real operand with largest available precision
10723 else
10729 -- If the operand is a literal (it could be a non-static and
10730 -- illegal exponentiation) check whether the use of Duration
10731 -- is potentially inaccurate.
10736 then
10737 Error_Msg_N
10740 Error_Msg_N
10747 then
10750 else
10759 -- In SPARK, a type conversion between array types should be restricted
10760 -- to types which have matching static bounds.
10762 -- Protect call to Matching_Static_Array_Bounds to avoid costly
10763 -- operation if not needed.
10770 then
10771 Check_SPARK_05_Restriction
10775 -- In formal mode, the operand of an ancestor type conversion must be an
10776 -- object (not an expression).
10784 then
10790 -- Note: we do the Eval_Type_Conversion call before applying the
10791 -- required checks for a subtype conversion. This is important, since
10792 -- both are prepared under certain circumstances to change the type
10793 -- conversion to a constraint error node, but in the case of
10794 -- Eval_Type_Conversion this may reflect an illegality in the static
10795 -- case, and we would miss the illegality (getting only a warning
10796 -- message), if we applied the type conversion checks first.
10800 -- Even when evaluation is not possible, we may be able to simplify the
10801 -- conversion or its expression. This needs to be done before applying
10802 -- checks, since otherwise the checks may use the original expression
10803 -- and defeat the simplifications. This is specifically the case for
10804 -- elimination of the floating-point Truncation attribute in
10805 -- float-to-int conversions.
10809 -- If after evaluation we still have a type conversion, then we may need
10810 -- to apply checks required for a subtype conversion.
10812 -- Skip these type conversion checks if universal fixed operands
10813 -- operands involved, since range checks are handled separately for
10814 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
10820 then
10824 -- Issue warning for conversion of simple object to its own type. We
10825 -- have to test the original nodes, since they may have been rewritten
10826 -- by various optimizations.
10830 -- Here we test for a redundant conversion if the warning mode is
10831 -- active (and was not locally reset), and we have a type conversion
10832 -- from source not appearing in a generic instance.
10834 if Test_Redundant
10837 and then not In_Instance
10838 then
10842 -- If the node is part of a larger expression, the Target_Type
10843 -- may not be the original type of the node if the context is a
10844 -- condition. Recover original type to see if conversion is needed.
10848 then
10852 -- If we have an entity name, then give the warning if the entity
10853 -- is the right type, or if it is a loop parameter covered by the
10854 -- original type (that's needed because loop parameters have an
10855 -- odd subtype coming from the bounds).
10858 and then
10860 or else
10864 -- If not an entity, then type of expression must match
10867 then
10868 -- One more check, do not give warning if the analyzed conversion
10869 -- has an expression with non-static bounds, and the bounds of the
10870 -- target are static. This avoids junk warnings in cases where the
10871 -- conversion is necessary to establish staticness, for example in
10872 -- a case statement.
10876 then
10879 -- Finally, if this type conversion occurs in a context requiring
10880 -- a prefix, and the expression is a qualified expression then the
10881 -- type conversion is not redundant, since a qualified expression
10882 -- is not a prefix, whereas a type conversion is. For example, "X
10883 -- := T'(Funx(...)).Y;" is illegal because a selected component
10884 -- requires a prefix, but a type conversion makes it legal: "X :=
10885 -- T(T'(Funx(...))).Y;"
10887 -- In Ada 2012, a qualified expression is a name, so this idiom is
10888 -- no longer needed, but we still suppress the warning because it
10889 -- seems unfriendly for warnings to pop up when you switch to the
10890 -- newer language version.
10894 N_Indexed_Component,
10895 N_Selected_Component,
10896 N_Slice,
10897 N_Explicit_Dereference)
10898 then
10901 -- Never warn on conversion to Long_Long_Integer'Base since
10902 -- that is most likely an artifact of the extended overflow
10903 -- checking and comes from complex expanded code.
10908 -- Here we give the redundant conversion warning. If it is an
10909 -- entity, give the name of the entity in the message. If not,
10910 -- just mention the expression.
10912 -- Shoudn't we test Warn_On_Redundant_Constructs here ???
10914 else
10917 Error_Msg_NE -- CODEFIX
10920 else
10921 Error_Msg_NE
10929 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
10930 -- No need to perform any interface conversion if the type of the
10931 -- expression coincides with the target type.
10934 and then Expander_Active
10936 then
10937 declare
10941 begin
10942 -- If the type of the operand is a limited view, use nonlimited
10943 -- view when available. If it is a class-wide type, recover the
10944 -- class-wide type of the nonlimited view.
10948 then
10964 -- Conversion from interface type
10968 -- Ada 2005 (AI-217): Handle entities from limited views
10972 Error_Msg_NE -- CODEFIX
10975 Error_Msg_N
10977 N);
10980 and then not
10983 then
10985 Error_Msg_NE -- CODEFIX
10988 Error_Msg_N
10990 N);
10992 else
10996 -- Conversion to interface type
11000 -- Handle subtypes
11007 or else Interface_Present_In_Ancestor
11010 then
11012 else
11015 Error_Msg_N
11023 -- Ada 2012: if target type has predicates, the result requires a
11024 -- predicate check. If the context is a call to another predicate
11025 -- check we must prevent infinite recursion.
11031 or else
11033 then
11036 else
11041 -- If at this stage we have a real to integer conversion, make sure
11042 -- that the Do_Range_Check flag is set, because such conversions in
11043 -- general need a range check. We only need this if expansion is off
11044 -- or we are in GNATProve mode.
11050 then
11054 -- Generating C code a type conversion of an access to constrained
11055 -- array type to access to unconstrained array type involves building
11056 -- a fat pointer which in general cannot be generated on the fly. We
11057 -- remove side effects in order to store the result of the conversion
11058 -- into a temporary.
11060 if Modify_Tree_For_C
11067 then
11072 ----------------------
11073 -- Resolve_Unary_Op --
11074 ----------------------
11083 begin
11086 Check_SPARK_05_Restriction
11090 -- Deal with intrinsic unary operators
11096 then
11101 -- Deal with universal cases
11104 or else
11106 then
11113 -- Generate warning for expressions like abs (x mod 2)
11115 if Warn_On_Redundant_Constructs
11117 then
11121 Error_Msg_N -- CODEFIX
11126 -- Deal with reference generation
11133 -- Set overflow checking bit. Much cleverer code needed here eventually
11134 -- and perhaps the Resolve routines should be separated for the various
11135 -- arithmetic operations, since they will need different processing ???
11143 -- Generate warning for expressions like -5 mod 3 for integers. No need
11144 -- to worry in the floating-point case, since parens do not affect the
11145 -- result so there is no point in giving in a warning.
11147 declare
11156 begin
11157 if Warn_On_Questionable_Missing_Parens
11161 then
11164 -- We are looking for cases where the right operand is not
11165 -- parenthesized, and is a binary operator, multiply, divide, or
11166 -- mod. These are the cases where the grouping can affect results.
11170 then
11171 -- For mod, we always give the warning, since the value is
11172 -- affected by the parenthesization (e.g. (-5) mod 315 /=
11173 -- -(5 mod 315)). But for the other cases, the only concern is
11174 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
11175 -- overflows, but (-2) * 64 does not). So we try to give the
11176 -- message only when overflow is possible.
11180 then
11185 else
11191 else
11195 -- Note that the test below is deliberately excluding the
11196 -- largest negative number, since that is a potentially
11197 -- troublesome case (e.g. -2 * x, where the result is the
11198 -- largest negative integer has an overflow with 2 * x).
11205 -- For the multiplication case, the only case we have to worry
11206 -- about is when (-a)*b is exactly the largest negative number
11207 -- so that -(a*b) can cause overflow. This can only happen if
11208 -- a is a power of 2, and more generally if any operand is a
11209 -- constant that is not a power of 2, then the parentheses
11210 -- cannot affect whether overflow occurs. We only bother to
11211 -- test the left most operand
11213 -- Loop looking at left operands for one that has known value
11220 -- Operand value of 0 or 1 skips warning
11225 -- Otherwise check power of 2, if power of 2, warn, if
11226 -- anything else, skip warning.
11228 else
11232 else
11241 -- Keep looking at left operands
11246 -- For rem or "/" we can only have a problematic situation
11247 -- if the divisor has a value of minus one or one. Otherwise
11248 -- overflow is impossible (divisor > 1) or we have a case of
11249 -- division by zero in any case.
11254 then
11258 -- If we fall through warning should be issued
11260 -- Shouldn't we test Warn_On_Questionable_Missing_Parens ???
11262 Error_Msg_N
11269 ----------------------------------
11270 -- Resolve_Unchecked_Expression --
11271 ----------------------------------
11273 procedure Resolve_Unchecked_Expression
11276 is
11277 begin
11282 ---------------------------------------
11283 -- Resolve_Unchecked_Type_Conversion --
11284 ---------------------------------------
11286 procedure Resolve_Unchecked_Type_Conversion
11289 is
11295 begin
11296 -- Resolve operand using its own type
11300 -- In an inlined context, the unchecked conversion may be applied
11301 -- to a literal, in which case its type is the type of the context.
11302 -- (In other contexts conversions cannot apply to literals).
11304 if In_Inlined_Body
11308 then
11316 ------------------------------
11317 -- Rewrite_Operator_As_Call --
11318 ------------------------------
11325 begin
11332 New_N :=
11343 ------------------------------
11344 -- Rewrite_Renamed_Operator --
11345 ------------------------------
11347 procedure Rewrite_Renamed_Operator
11351 is
11356 begin
11357 -- Do not perform this transformation within a pre/postcondition,
11358 -- because the expression will be re-analyzed, and the transformation
11359 -- might affect the visibility of the operator, e.g. in an instance.
11360 -- Note that fully analyzed and expanded pre/postconditions appear as
11361 -- pragma Check equivalents.
11367 -- Rewrite the operator node using the real operator, not its renaming.
11368 -- Exclude user-defined intrinsic operations of the same name, which are
11369 -- treated separately and rewritten as calls.
11378 -- Indicate that both the original entity and its renaming are
11379 -- referenced at this point.
11390 -- If the context type is private, add the appropriate conversions so
11391 -- that the operator is applied to the full view. This is done in the
11392 -- routines that resolve intrinsic operators.
11396 when N_Op_Add
11397 | N_Op_Divide
11398 | N_Op_Expon
11399 | N_Op_Mod
11400 | N_Op_Multiply
11401 | N_Op_Rem
11402 | N_Op_Subtract
11403 =>
11406 when N_Op_Abs
11407 | N_Op_Minus
11408 | N_Op_Plus
11409 =>
11419 -- Operator renames a user-defined operator of the same name. Use the
11420 -- original operator in the node, which is the one Gigi knows about.
11427 -----------------------
11428 -- Set_Slice_Subtype --
11429 -----------------------
11431 -- Build an implicit subtype declaration to represent the type delivered by
11432 -- the slice. This is an abbreviated version of an array subtype. We define
11433 -- an index subtype for the slice, using either the subtype name or the
11434 -- discrete range of the slice. To be consistent with index usage elsewhere
11435 -- we create a list header to hold the single index. This list is not
11436 -- otherwise attached to the syntax tree.
11447 begin
11453 else
11454 -- We force the evaluation of a range. This is definitely needed in
11455 -- the renamed case, and seems safer to do unconditionally. Note in
11456 -- any case that since we will create and insert an Itype referring
11457 -- to this range, we must make sure any side effect removal actions
11458 -- are inserted before the Itype definition.
11464 -- If the discrete range is given by a subtype indication, the
11465 -- type of the slice is the base of the subtype mark.
11468 declare
11470 begin
11479 -- Take a new copy of Drange (where bounds have been rewritten to
11480 -- reference side-effect-free names). Using a separate tree ensures
11481 -- that further expansion (e.g. while rewriting a slice assignment
11482 -- into a FOR loop) does not attempt to remove side effects on the
11483 -- bounds again (which would cause the bounds in the index subtype
11484 -- definition to refer to temporaries before they are defined) (the
11485 -- reason is that some names are considered side effect free here
11486 -- for the subtype, but not in the context of a loop iteration
11487 -- scheme).
11508 -- The Etype of the existing Slice node is reset to this slice subtype.
11509 -- Its bounds are obtained from its first index.
11513 -- For packed slice subtypes, freeze immediately (except in the case of
11514 -- being in a "spec expression" where we never freeze when we first see
11515 -- the expression).
11520 -- For all other cases insert an itype reference in the slice's actions
11521 -- so that the itype is frozen at the proper place in the tree (i.e. at
11522 -- the point where actions for the slice are analyzed). Note that this
11523 -- is different from freezing the itype immediately, which might be
11524 -- premature (e.g. if the slice is within a transient scope). This needs
11525 -- to be done only if expansion is enabled.
11532 --------------------------------
11533 -- Set_String_Literal_Subtype --
11534 --------------------------------
11542 begin
11554 -- The low bound is set from the low bound of the corresponding index
11555 -- type. Note that we do not store the high bound in the string literal
11556 -- subtype, but it can be deduced if necessary from the length and the
11557 -- low bound.
11562 -- If the lower bound is not static we create a range for the string
11563 -- literal, using the index type and the known length of the literal.
11564 -- The index type is not necessarily Positive, so the upper bound is
11565 -- computed as T'Val (T'Pos (Low_Bound) + L - 1).
11567 else
11568 declare
11574 Prefix =>
11578 Left_Opnd =>
11581 Prefix =>
11583 Expressions =>
11585 Right_Opnd =>
11594 begin
11596 Set_String_Literal_Low_Bound
11599 else
11600 -- If the index type is an enumeration type, build bounds
11601 -- expression with attributes.
11603 Set_String_Literal_Low_Bound
11607 Prefix =>
11614 -- Build bona fide subtype for the string, and wrap it in an
11615 -- unchecked conversion, because the backend expects the
11616 -- String_Literal_Subtype to have a static lower bound.
11618 Index_Subtype :=
11625 -- In the context, the Index_Type may already have a constraint,
11626 -- so use common base type on string subtype. The base type may
11627 -- be used when generating attributes of the string, for example
11628 -- in the context of a slice assignment.
11653 ------------------------------
11654 -- Simplify_Type_Conversion --
11655 ------------------------------
11658 begin
11660 declare
11665 begin
11666 -- Special processing if the conversion is the expression of a
11667 -- Rounding or Truncation attribute reference. In this case we
11668 -- replace:
11670 -- ityp (ftyp'Rounding (x)) or ityp (ftyp'Truncation (x))
11672 -- by
11674 -- ityp (x)
11676 -- with the Float_Truncate flag set to False or True respectively,
11677 -- which is more efficient.
11680 and then
11686 Name_Truncation)
11687 then
11688 declare
11691 begin
11701 -----------------------------
11702 -- Unique_Fixed_Point_Type --
11703 -----------------------------
11712 -- Give error messages for true ambiguity. Messages are posted on node
11713 -- N, and entities T1, T2 are the possible interpretations.
11715 -----------------------
11716 -- Fixed_Point_Error --
11717 -----------------------
11720 begin
11726 -- Start of processing for Unique_Fixed_Point_Type
11728 begin
11729 -- The operations on Duration are visible, so Duration is always a
11730 -- possible interpretation.
11734 -- Look for fixed-point types in enclosing scopes
11743 then
11745 Fixed_Point_Error;
11747 else
11758 -- Look for visible fixed type declarations in the context
11769 then
11771 Fixed_Point_Error;
11773 else
11786 Error_Msg_NE
11788 else
11789 Error_Msg_NE
11796 ----------------------
11797 -- Valid_Conversion --
11798 ----------------------
11800 function Valid_Conversion
11805 is
11810 function Conversion_Check
11813 -- Little routine to post Msg if Valid is False, returns Valid value
11816 -- If Report_Errs, then calls Errout.Error_Msg_N with its arguments
11818 procedure Conversion_Error_NE
11822 -- If Report_Errs, then calls Errout.Error_Msg_NE with its arguments
11824 function Valid_Tagged_Conversion
11827 -- Specifically test for validity of tagged conversions
11830 -- Check index and component conformance, and accessibility levels if
11831 -- the component types are anonymous access types (Ada 2005).
11833 ----------------------
11834 -- Conversion_Check --
11835 ----------------------
11837 function Conversion_Check
11840 is
11841 begin
11842 if not Valid
11844 -- A generic unit has already been analyzed and we have verified
11845 -- that a particular conversion is OK in that context. Since the
11846 -- instance is reanalyzed without relying on the relationships
11847 -- established during the analysis of the generic, it is possible
11848 -- to end up with inconsistent views of private types. Do not emit
11849 -- the error message in such cases. The rest of the machinery in
11850 -- Valid_Conversion still ensures the proper compatibility of
11851 -- target and operand types.
11853 and then not In_Instance
11854 then
11861 ------------------------
11862 -- Conversion_Error_N --
11863 ------------------------
11866 begin
11872 -------------------------
11873 -- Conversion_Error_NE --
11874 -------------------------
11876 procedure Conversion_Error_NE
11880 is
11881 begin
11887 ----------------------------
11888 -- Valid_Array_Conversion --
11889 ----------------------------
11906 begin
11907 -- Error if wrong number of dimensions
11909 if
11911 then
11912 Conversion_Error_N
11916 -- Number of dimensions matches
11918 else
11919 -- Loop through indexes of the two arrays
11927 -- Error if index types are incompatible
11933 then
11934 Conversion_Error_N
11936 Operand);
11944 -- If component types have same base type, all set
11949 -- Here if base types of components are not the same. The only
11950 -- time this is allowed is if we have anonymous access types.
11952 -- The conversion of arrays of anonymous access types can lead
11953 -- to dangling pointers. AI-392 formalizes the accessibility
11954 -- checks that must be applied to such conversions to prevent
11955 -- out-of-scope references.
11957 elsif Ekind_In
11959 E_Anonymous_Access_Subprogram_Type)
11961 and then
11963 then
11966 then
11969 Conversion_Error_N
11979 -- Conversion not allowed because of accessibility levels
11981 else
11982 Conversion_Error_N
11988 else
11992 -- All other cases where component base types do not match
11994 else
11995 Conversion_Error_N
11997 Operand);
12001 -- Check that component subtypes statically match. For numeric
12002 -- types this means that both must be either constrained or
12003 -- unconstrained. For enumeration types the bounds must match.
12004 -- All of this is checked in Subtypes_Statically_Match.
12006 if not Subtypes_Statically_Match
12008 then
12009 Conversion_Error_N
12018 -----------------------------
12019 -- Valid_Tagged_Conversion --
12020 -----------------------------
12022 function Valid_Tagged_Conversion
12025 is
12026 begin
12027 -- Upward conversions are allowed (RM 4.6(22))
12031 then
12034 -- Downward conversion are allowed if the operand is class-wide
12035 -- (RM 4.6(23)).
12039 then
12044 then
12045 return
12049 -- Ada 2005 (AI-251): The conversion to/from interface types is
12050 -- always valid. The types involved may be class-wide (sub)types.
12054 then
12057 -- If the operand is a class-wide type obtained through a limited_
12058 -- with clause, and the context includes the nonlimited view, use
12059 -- it to determine whether the conversion is legal.
12065 then
12070 then
12073 else
12074 Conversion_Error_NE
12081 -- Start of processing for Valid_Conversion
12083 begin
12087 declare
12095 begin
12096 -- Remove procedure calls, which syntactically cannot appear in
12097 -- this context, but which cannot be removed by type checking,
12098 -- because the context does not impose a type.
12100 -- The node may be labelled overloaded, but still contain only one
12101 -- interpretation because others were discarded earlier. If this
12102 -- is the case, retain the single interpretation if legal.
12110 then
12111 -- More than one candidate interpretation is available
12119 -- When compiling for a system where Address is of a visible
12120 -- integer type, spurious ambiguities can be produced when
12121 -- arithmetic operations have a literal operand and return
12122 -- System.Address or a descendant of it. These ambiguities
12123 -- are usually resolved by the context, but for conversions
12124 -- there is no context type and the removal of the spurious
12125 -- operations must be done explicitly here.
12127 if not Address_Is_Private
12129 then
12154 Conversion_Error_N
12157 -- If the interpretation involves a standard operator, use
12158 -- the location of the type, which may be user-defined.
12162 else
12166 Conversion_Error_N -- CODEFIX
12171 else
12175 Conversion_Error_N -- CODEFIX
12187 -- Deal with conversion of integer type to address if the pragma
12188 -- Allow_Integer_Address is in effect. We convert the conversion to
12189 -- an unchecked conversion in this case and we are all done.
12197 -- If we are within a child unit, check whether the type of the
12198 -- expression has an ancestor in a parent unit, in which case it
12199 -- belongs to its derivation class even if the ancestor is private.
12200 -- See RM 7.3.1 (5.2/3).
12204 -- Numeric types
12208 -- A universal fixed expression can be converted to any numeric type
12213 -- Also no need to check when in an instance or inlined body, because
12214 -- the legality has been established when the template was analyzed.
12215 -- Furthermore, numeric conversions may occur where only a private
12216 -- view of the operand type is visible at the instantiation point.
12217 -- This results in a spurious error if we check that the operand type
12218 -- is a numeric type.
12220 -- Note: in a previous version of this unit, the following tests were
12221 -- applied only for generated code (Comes_From_Source set to False),
12222 -- but in fact the test is required for source code as well, since
12223 -- this situation can arise in source code.
12228 -- Otherwise we need the conversion check
12230 else
12231 return Conversion_Check
12233 or else
12239 -- Array types
12245 then
12246 Conversion_Error_N
12250 else
12254 -- Ada 2005 (AI-251): Internally generated conversions of access to
12255 -- interface types added to force the displacement of the pointer to
12256 -- reference the corresponding dispatch table.
12261 then
12264 -- Ada 2005 (AI-251): Anonymous access types where target references an
12265 -- interface type.
12269 E_Anonymous_Access_Type)
12271 then
12272 -- Check the static accessibility rule of 4.6(17). Note that the
12273 -- check is not enforced when within an instance body, since the
12274 -- RM requires such cases to be caught at run time.
12276 -- If the operand is a rewriting of an allocator no check is needed
12277 -- because there are no accessibility issues.
12285 then
12286 -- In an instance, this is a run-time check, but one we know
12287 -- will fail, so generate an appropriate warning. The raise
12288 -- will be generated by Expand_N_Type_Conversion.
12292 Conversion_Error_N
12294 Operand);
12297 else
12298 Conversion_Error_N
12300 Operand);
12304 -- Special accessibility checks are needed in the case of access
12305 -- discriminants declared for a limited type.
12309 then
12310 -- When the operand is a selected access discriminant the check
12311 -- needs to be made against the level of the object denoted by
12312 -- the prefix of the selected name (Object_Access_Level handles
12313 -- checking the prefix of the operand for this case).
12318 then
12319 -- In an instance, this is a run-time check, but one we know
12320 -- will fail, so generate an appropriate warning. The raise
12321 -- will be generated by Expand_N_Type_Conversion.
12325 Conversion_Error_N
12330 -- Real error if not in instance body
12332 else
12333 Conversion_Error_N
12340 -- The case of a reference to an access discriminant from
12341 -- within a limited type declaration (which will appear as
12342 -- a discriminal) is always illegal because the level of the
12343 -- discriminant is considered to be deeper than any (nameable)
12344 -- access type.
12348 and then
12351 then
12352 Conversion_Error_N
12354 Operand);
12362 -- General and anonymous access types
12365 E_Anonymous_Access_Type)
12366 and then
12367 Conversion_Check
12369 and then not
12371 E_Access_Protected_Subprogram_Type),
12373 then
12376 then
12377 Conversion_Error_N
12382 -- Check the static accessibility rule of 4.6(17). Note that the
12383 -- check is not enforced when within an instance body, since the RM
12384 -- requires such cases to be caught at run time.
12389 N_Object_Declaration
12390 then
12391 -- Ada 2012 (AI05-0149): Perform legality checking on implicit
12392 -- conversions from an anonymous access type to a named general
12393 -- access type. Such conversions are not allowed in the case of
12394 -- access parameters and stand-alone objects of an anonymous
12395 -- access type. The implicit conversion case is recognized by
12396 -- testing that Comes_From_Source is False and that it's been
12397 -- rewritten. The Comes_From_Source test isn't sufficient because
12398 -- nodes in inlined calls to predefined library routines can have
12399 -- Comes_From_Source set to False. (Is there a better way to test
12400 -- for implicit conversions???)
12407 then
12410 -- Implicit conversions aren't allowed for objects of an
12411 -- anonymous access type, since such objects have nonstatic
12412 -- levels in Ada 2012.
12415 N_Object_Declaration
12416 then
12417 Conversion_Error_N
12422 -- Implicit conversions aren't allowed for anonymous access
12423 -- parameters. The "not Is_Local_Anonymous_Access_Type" test
12424 -- is done to exclude anonymous access results.
12428 N_Function_Specification,
12429 N_Procedure_Specification)
12430 then
12431 Conversion_Error_N
12436 -- This is a case where there's an enclosing object whose
12437 -- to which the "statically deeper than" relationship does
12438 -- not apply (such as an access discriminant selected from
12439 -- a dereference of an access parameter).
12443 then
12444 Conversion_Error_N
12449 -- In other cases, the level of the operand's type must be
12450 -- statically less deep than that of the target type, else
12451 -- implicit conversion is disallowed (by RM12-8.6(27.1/3)).
12455 then
12456 Conversion_Error_N
12465 then
12466 -- In an instance, this is a run-time check, but one we know
12467 -- will fail, so generate an appropriate warning. The raise
12468 -- will be generated by Expand_N_Type_Conversion.
12472 Conversion_Error_N
12474 Operand);
12477 -- If not in an instance body, this is a real error
12479 else
12480 -- Avoid generation of spurious error message
12483 Conversion_Error_N
12485 Operand);
12491 -- Special accessibility checks are needed in the case of access
12492 -- discriminants declared for a limited type.
12496 then
12497 -- When the operand is a selected access discriminant the check
12498 -- needs to be made against the level of the object denoted by
12499 -- the prefix of the selected name (Object_Access_Level handles
12500 -- checking the prefix of the operand for this case).
12505 then
12506 -- In an instance, this is a run-time check, but one we know
12507 -- will fail, so generate an appropriate warning. The raise
12508 -- will be generated by Expand_N_Type_Conversion.
12512 Conversion_Error_N
12517 -- If not in an instance body, this is a real error
12519 else
12520 Conversion_Error_N
12527 -- The case of a reference to an access discriminant from
12528 -- within a limited type declaration (which will appear as
12529 -- a discriminal) is always illegal because the level of the
12530 -- discriminant is considered to be deeper than any (nameable)
12531 -- access type.
12534 and then
12537 then
12538 Conversion_Error_N
12540 Operand);
12546 -- In the presence of limited_with clauses we have to use nonlimited
12547 -- views, if available.
12551 -- Helper function to handle limited views
12553 --------------------------
12554 -- Full_Designated_Type --
12555 --------------------------
12560 begin
12561 -- Handle the limited view of a type
12565 then
12567 else
12572 -- Local Declarations
12580 -- Start of processing for Check_Limited
12582 begin
12586 else
12588 Conversion_Error_NE
12593 -- Ada 2005 AI-384: legality rule is symmetric in both
12594 -- designated types. The conversion is legal (with possible
12595 -- constraint check) if either designated type is
12596 -- unconstrained.
12599 or else
12601 and then
12604 then
12605 -- Special case, if Value_Size has been used to make the
12606 -- sizes different, the conversion is not allowed even
12607 -- though the subtypes statically match.
12612 then
12613 Conversion_Error_NE
12616 Conversion_Error_NE
12621 -- Normal case where conversion is allowed
12623 else
12627 else
12628 Error_Msg_NE
12636 -- Access to subprogram types. If the operand is an access parameter,
12637 -- the type has a deeper accessibility that any master, and cannot be
12638 -- assigned. We must make an exception if the conversion is part of an
12639 -- assignment and the target is the return object of an extended return
12640 -- statement, because in that case the accessibility check takes place
12641 -- after the return.
12645 -- Note: this test of Opnd_Type is there to prevent entering this
12646 -- branch in the case of a remote access to subprogram type, which
12647 -- is internally represented as an E_Record_Type.
12650 then
12654 and then
12658 then
12659 Conversion_Error_N
12661 Operand);
12662 Conversion_Error_N
12665 Operand);
12667 Error_Msg_NE
12672 -- Check that the designated types are subtype conformant
12678 -- Check the static accessibility rule of 4.6(20)
12682 then
12683 Conversion_Error_N
12685 Operand);
12687 -- Check that if the operand type is declared in a generic body,
12688 -- then the target type must be declared within that same body
12689 -- (enforces last sentence of 4.6(20)).
12692 declare
12698 begin
12705 Conversion_Error_N
12714 -- Remote access to subprogram types
12718 then
12719 -- It is valid to convert from one RAS type to another provided
12720 -- that their specification statically match.
12722 -- Note: at this point, remote access to subprogram types have been
12723 -- expanded to their E_Record_Type representation, and we need to
12724 -- go back to the original access type definition using the
12725 -- Corresponding_Remote_Type attribute in order to check that the
12726 -- designated profiles match.
12731 Check_Subtype_Conformant
12734 Old_Id =>
12736 Err_Loc =>
12737 N);
12740 -- If it was legal in the generic, it's legal in the instance
12745 -- If both are tagged types, check legality of view conversions
12748 and then
12750 then
12753 -- Types derived from the same root type are convertible
12758 -- In an instance or an inlined body, there may be inconsistent views of
12759 -- the same type, or of types derived from a common root.
12762 and then
12765 then
12768 -- Special check for common access type error case
12772 then
12774 Conversion_Error_NE -- CODEFIX
12778 -- Here we have a real conversion error
12780 else
12781 Conversion_Error_NE