| blob | 58ee4036948214a1bac001270fd68a6b465cdffb |
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.
211 function Operator_Kind
214 -- Utility to map the name of an operator into the corresponding Node. Used
215 -- by other node rewriting procedures.
218 -- Resolve actuals of call, and add default expressions for missing ones.
219 -- N is the Node_Id for the subprogram call, and Nam is the entity of the
220 -- called subprogram.
223 -- Called from Resolve_Call, when the prefix denotes an entry or element
224 -- of entry family. Actuals are resolved as for subprograms, and the node
225 -- is rebuilt as an entry call. Also called for protected operations. Typ
226 -- is the context type, which is used when the operation is a protected
227 -- function with no arguments, and the return value is indexed.
230 -- A call to a user-defined intrinsic operator is rewritten as a call to
231 -- the corresponding predefined operator, with suitable conversions. Note
232 -- that this applies only for intrinsic operators that denote predefined
233 -- operators, not ones that are intrinsic imports of back-end builtins.
236 -- Ditto, for arithmetic unary operators
239 -- If an operator node resolves to a call to a user-defined operator,
240 -- rewrite the node as a function call.
242 procedure Make_Call_Into_Operator
246 -- Inverse transformation: if an operator is given in functional notation,
247 -- then after resolving the node, transform into an operator node, so that
248 -- operands are resolved properly. Recall that predefined operators do not
249 -- have a full signature and special resolution rules apply.
251 procedure Rewrite_Renamed_Operator
255 -- An operator can rename another, e.g. in an instantiation. In that
256 -- case, the proper operator node must be constructed and resolved.
259 -- The String_Literal_Subtype is built for all strings that are not
260 -- operands of a static concatenation operation. If the argument is not
261 -- a N_String_Literal node, then the call has no effect.
264 -- Build subtype of array type, with the range specified by the slice
267 -- Called after N has been resolved and evaluated, but before range checks
268 -- have been applied. Currently simplifies a combination of floating-point
269 -- to integer conversion and Rounding or Truncation attribute.
272 -- A universal_fixed expression in an universal context is unambiguous if
273 -- there is only one applicable fixed point type. Determining whether there
274 -- is only one requires a search over all visible entities, and happens
275 -- only in very pathological cases (see 6115-006).
277 -------------------------
278 -- Ambiguous_Character --
279 -------------------------
284 begin
288 -- First the ones in Standard
293 -- Include Wide_Wide_Character in Ada 2005 mode
299 -- Now any other types that match
309 -------------------------
310 -- Analyze_And_Resolve --
311 -------------------------
314 begin
320 begin
325 -- Versions with check(s) suppressed
327 procedure Analyze_And_Resolve
331 is
334 begin
336 declare
338 begin
344 else
345 declare
347 begin
355 and then Scope_Is_Transient
356 then
357 -- This can only happen if a transient scope was created for an inner
358 -- expression, which will be removed upon completion of the analysis
359 -- of an enclosing construct. The transient scope must have the
360 -- suppress status of the enclosing environment, not of this Analyze
361 -- call.
364 Scope_Suppress;
368 procedure Analyze_And_Resolve
371 is
374 begin
376 declare
378 begin
384 else
385 declare
387 begin
396 Scope_Suppress;
400 ----------------------------
401 -- Check_Discriminant_Use --
402 ----------------------------
410 begin
411 -- Any use in a spec-expression is legal
418 -- Discriminant cannot be used to constrain a scalar type
425 then
430 -- The following check catches the unusual case where a
431 -- discriminant appears within an index constraint that is part
432 -- of a larger expression within a constraint on a component,
433 -- e.g. "C : Int range 1 .. F (new A(1 .. D))". For now we only
434 -- check case of record components, and note that a similar check
435 -- should also apply in the case of discriminant constraints
436 -- below. ???
438 -- Note that the check for N_Subtype_Declaration below is to
439 -- detect the valid use of discriminants in the constraints of a
440 -- subtype declaration when this subtype declaration appears
441 -- inside the scope of a record type (which is syntactically
442 -- illegal, but which may be created as part of derived type
443 -- processing for records). See Sem_Ch3.Build_Derived_Record_Type
444 -- for more info.
448 and then not
450 and then
452 N_Subtype_Declaration)
454 then
455 Error_Msg_N
460 -- Detect a common error:
462 -- type R (D : Positive := 100) is record
463 -- Name : String (1 .. D);
464 -- end record;
466 -- The default value causes an object of type R to be allocated
467 -- with room for Positive'Last characters. The RM does not mandate
468 -- the allocation of the maximum size, but that is what GNAT does
469 -- so we should warn the programmer that there is a problem.
478 -- Return True if type T has a large enough range that any
479 -- array whose index type covered the whole range of the type
480 -- would likely raise Storage_Error.
482 ------------------------
483 -- Large_Storage_Type --
484 ------------------------
487 begin
488 -- The type is considered large if its bounds are known at
489 -- compile time and if it requires at least as many bits as
490 -- a Positive to store the possible values.
494 and then
499 -- Start of processing for Check_Large
501 begin
502 -- Check that the Disc has a large range
508 -- If the enclosing type is limited, we allocate only the
509 -- default value, not the maximum, and there is no need for
510 -- a warning.
516 -- Check that it is the high bound
520 then
524 -- Check the array allows a large range at this bound. First
525 -- find the array
539 -- Next, find the dimension
547 loop
556 -- Now, check the dimension has a large range
562 -- Warn about the danger
564 Error_Msg_N
574 -- Legal case is in index or discriminant constraint
577 N_Discriminant_Association)
578 then
580 Error_Msg_N
585 then
586 Error_Msg_N
592 -- Otherwise, context is an expression. It should not be within (i.e. a
593 -- subexpression of) a constraint for a component.
595 else
599 N_Subtype_Indication,
600 N_Entry_Declaration)
601 loop
607 -- If the discriminant is used in an expression that is a bound of a
608 -- scalar type, an Itype is created and the bounds are attached to
609 -- its range, not to the original subtype indication. Such use is of
610 -- course a double fault.
614 N_Derived_Type_Definition)
617 -- The constraint itself may be given by a subtype indication,
618 -- rather than by a more common discrete range.
621 and then
625 then
626 Error_Msg_N
632 --------------------------------
633 -- Check_For_Visible_Operator --
634 --------------------------------
637 begin
639 Error_Msg_NE -- CODEFIX
641 Error_Msg_N -- CODEFIX
646 ----------------------------------
647 -- Check_Fully_Declared_Prefix --
648 ----------------------------------
650 procedure Check_Fully_Declared_Prefix
653 is
654 begin
655 -- Check that the designated type of the prefix of a dereference is
656 -- not an incomplete type. This cannot be done unconditionally, because
657 -- dereferences of private types are legal in default expressions. This
658 -- case is taken care of in Check_Fully_Declared, called below. There
659 -- are also 2005 cases where it is legal for the prefix to be unfrozen.
661 -- This consideration also applies to similar checks for allocators,
662 -- qualified expressions, and type conversions.
664 -- An additional exception concerns other per-object expressions that
665 -- are not directly related to component declarations, in particular
666 -- representation pragmas for tasks. These will be per-object
667 -- expressions if they depend on discriminants or some global entity.
668 -- If the task has access discriminants, the designated type may be
669 -- incomplete at the point the expression is resolved. This resolution
670 -- takes place within the body of the initialization procedure, where
671 -- the discriminant is replaced by its discriminal.
675 then
678 -- Ada 2005 (AI-326): Tagged incomplete types allowed. The wrong usages
679 -- are handled by Analyze_Access_Attribute, Analyze_Assignment,
680 -- Analyze_Object_Renaming, and Freeze_Entity.
686 E_Incomplete_Type
688 then
690 else
695 ------------------------------
696 -- Check_Infinite_Recursion --
697 ------------------------------
704 -- Check whether list of actuals is identical to list of formals of
705 -- called function (which is also the enclosing scope).
707 ------------------------
708 -- Same_Argument_List --
709 ------------------------
716 begin
719 else
737 -- Start of processing for Check_Infinite_Recursion
739 begin
740 -- Special case, if this is a procedure call and is a call to the
741 -- current procedure with the same argument list, then this is for
742 -- sure an infinite recursion and we insert a call to raise SE.
746 and then Same_Argument_List
747 then
748 declare
750 begin
754 then
766 -- If not that special case, search up tree, quitting if we reach a
767 -- construct (e.g. a conditional) that tells us that this is not a
768 -- case for an infinite recursion warning.
771 loop
774 -- If no parent, then we were not inside a subprogram, this can for
775 -- example happen when processing certain pragmas in a spec. Just
776 -- return False in this case.
782 -- Done if we get to subprogram body, this is definitely an infinite
783 -- recursion case if we did not find anything to stop us.
787 -- If appearing in conditional, result is false
790 N_And_Then,
791 N_Case_Expression,
792 N_Case_Statement,
793 N_If_Expression,
794 N_If_Statement)
795 then
800 then
801 -- If the call is the expression of a return statement and the
802 -- actuals are identical to the formals, it's worth a warning.
803 -- However, we skip this if there is an immediately preceding
804 -- raise statement, since the call is never executed.
806 -- Furthermore, this corresponds to a common idiom:
808 -- function F (L : Thing) return Boolean is
809 -- begin
810 -- raise Program_Error;
811 -- return F (L);
812 -- end F;
814 -- for generating a stub function
817 and then Same_Argument_List
818 then
821 -- OK, return statement is in a statement list, look for raise
823 declare
826 begin
827 -- Skip past N_Freeze_Entity nodes generated by expansion
832 loop
836 -- If no raise statement, give warning. We look at the
837 -- original node, because in the case of "raise ... with
838 -- ...", the node has been transformed into a call.
841 and then
849 else
861 -------------------------------
862 -- Check_Initialization_Call --
863 -------------------------------
869 -- Check whether the creation of an object of the type will involve
870 -- use of the secondary stack. If T is a record type, this is true
871 -- if the expression for some component uses the secondary stack, e.g.
872 -- through a call to a function that returns an unconstrained value.
873 -- False if T is controlled, because cleanups occur elsewhere.
875 -------------
876 -- Uses_SS --
877 -------------
884 begin
885 -- Normally we want to use the underlying type, but if it's not set
886 -- then continue with T.
903 then
904 -- The expression for a dynamic component may be rewritten
905 -- as a dereference, so retrieve original node.
909 -- Return True if the expression is a call to a function
910 -- (including an attribute function such as Image, or a
911 -- user-defined operator) with a result that requires a
912 -- transient scope.
919 then
932 else
937 -- Start of processing for Check_Initialization_Call
939 begin
940 -- Establish a transient scope if the type needs it
947 ---------------------------------------
948 -- Check_No_Direct_Boolean_Operators --
949 ---------------------------------------
952 begin
955 then
956 -- Restriction only applies to original source code
963 -- Do style check (but skip if in instance, error is on template)
972 ------------------------------
973 -- Check_Parameterless_Call --
974 ------------------------------
980 -- If the prefix is of an access_to_subprogram type, the node must be
981 -- rewritten as a call. Ditto if the prefix is overloaded and all its
982 -- interpretations are access to subprograms.
984 ---------------------------
985 -- Prefix_Is_Access_Subp --
986 ---------------------------
992 begin
993 -- If the context is an attribute reference that can apply to
994 -- functions, this is never a parameterless call (RM 4.1.4(6)).
998 Name_Code_Address,
999 Name_Access)
1000 then
1005 return
1008 else
1013 then
1024 -- Start of processing for Check_Parameterless_Call
1026 begin
1027 -- Defend against junk stuff if errors already detected
1034 then
1041 -- If the context expects a value, and the name is a procedure, this is
1042 -- most likely a missing 'Access. Don't try to resolve the parameterless
1043 -- call, error will be caught when the outer call is analyzed.
1048 and then
1050 N_Function_Call,
1051 N_Procedure_Call_Statement)
1052 then
1056 -- Rewrite as call if overloadable entity that is (or could be, in the
1057 -- overloaded case) a function call. If we know for sure that the entity
1058 -- is an enumeration literal, we do not rewrite it.
1060 -- If the entity is the name of an operator, it cannot be a call because
1061 -- operators cannot have default parameters. In this case, this must be
1062 -- a string whose contents coincide with an operator name. Set the kind
1063 -- of the node appropriately.
1071 -- Rewrite as call if it is an explicit dereference of an expression of
1072 -- a subprogram access type, and the subprogram type is not that of a
1073 -- procedure or entry.
1075 or else
1078 -- Rewrite as call if it is a selected component which is a function,
1079 -- this is the case of a call to a protected function (which may be
1080 -- overloaded with other protected operations).
1082 or else
1085 or else
1087 E_Procedure)
1090 -- If one of the above three conditions is met, rewrite as call. Apply
1091 -- the rewriting only once.
1093 then
1096 then
1098 -- This may be a prefixed call that was not fully analyzed, e.g.
1099 -- an actual in an instance.
1104 then
1112 -- The node is the name of the parameterless call. Preserve its
1113 -- descendants, which may be complex expressions.
1117 -- If overloaded, overload set belongs to new copy
1121 -- Change node to parameterless function call (note that the
1122 -- Parameter_Associations associations field is left set to Empty,
1123 -- its normal default value since there are no parameters)
1141 --------------------------------
1142 -- Is_Atomic_Ref_With_Address --
1143 --------------------------------
1148 begin
1152 else
1153 declare
1156 begin
1164 -----------------------------
1165 -- Is_Definite_Access_Type --
1166 -----------------------------
1170 begin
1176 ----------------------
1177 -- Is_Predefined_Op --
1178 ----------------------
1181 begin
1182 -- Predefined operators are intrinsic subprograms
1188 -- A call to a back-end builtin is never a predefined operator
1199 -----------------------------
1200 -- Make_Call_Into_Operator --
1201 -----------------------------
1203 procedure Make_Call_Into_Operator
1207 is
1222 -- If the operand is not universal, and the operator is given by an
1223 -- expanded name, verify that the operand has an interpretation with a
1224 -- type defined in the given scope of the operator.
1227 -- Find a type of the given class in package Pack that contains the
1228 -- operator.
1230 ---------------------------
1231 -- Operand_Type_In_Scope --
1232 ---------------------------
1239 begin
1243 else
1257 ---------------
1258 -- Type_In_P --
1259 ---------------
1265 -- Verify that node is not part of the type declaration for the
1266 -- candidate type, which would otherwise be invisible.
1268 -------------
1269 -- In_Decl --
1270 -------------
1276 begin
1285 else
1288 loop
1291 else
1300 -- Start of processing for Type_In_P
1302 begin
1303 -- If the context type is declared in the prefix package, this is the
1304 -- desired base type.
1309 else
1323 -- Start of processing for Make_Call_Into_Operator
1325 begin
1328 -- Binary operator
1338 -- Unary operator
1340 else
1346 -- If the operator is denoted by an expanded name, and the prefix is
1347 -- not Standard, but the operator is a predefined one whose scope is
1348 -- Standard, then this is an implicit_operator, inserted as an
1349 -- interpretation by the procedure of the same name. This procedure
1350 -- overestimates the presence of implicit operators, because it does
1351 -- not examine the type of the operands. Verify now that the operand
1352 -- type appears in the given scope. If right operand is universal,
1353 -- check the other operand. In the case of concatenation, either
1354 -- argument can be the component type, so check the type of the result.
1355 -- If both arguments are literals, look for a type of the right kind
1356 -- defined in the given scope. This elaborate nonsense is brought to
1357 -- you courtesy of b33302a. The type itself must be frozen, so we must
1358 -- find the type of the proper class in the given scope.
1360 -- A final wrinkle is the multiplication operator for fixed point types,
1361 -- which is defined in Standard only, and not in the scope of the
1362 -- fixed point type itself.
1367 -- If this is a package renaming, get renamed entity, which will be
1368 -- the scope of the operands if operaton is type-correct.
1374 -- If the entity being called is defined in the given package, it is
1375 -- a renaming of a predefined operator, and known to be legal.
1379 then
1382 -- Visibility does not need to be checked in an instance: if the
1383 -- operator was not visible in the generic it has been diagnosed
1384 -- already, else there is an implicit copy of it in the instance.
1392 then
1397 -- Ada 2005 AI-420: Predefined equality on Universal_Access is
1398 -- available.
1403 then
1406 else
1415 and then Is_Binary
1417 then
1423 -- Verify that the scope contains a type that corresponds to
1424 -- the given literal. Optimize the case where Pack is Standard.
1445 else
1454 else
1463 then
1466 -- If the type is defined elsewhere, and the operator is not
1467 -- defined in the given scope (by a renaming declaration, e.g.)
1468 -- then this is an error as well. If an extension of System is
1469 -- present, and the type may be defined there, Pack must be
1470 -- System itself.
1477 then
1480 else
1486 then
1493 Error_Msg_NE
1498 -- Detect a mismatch between the context type and the result type
1499 -- in the named package, which is otherwise not detected if the
1500 -- operands are universal. Check is only needed if source entity is
1501 -- an operator, not a function that renames an operator.
1508 and then not In_Instance
1509 then
1512 then
1513 -- Already checked above
1517 -- Operator may be defined in an extension of System
1521 then
1524 else
1525 -- Could we use Wrong_Type here??? (this would require setting
1526 -- Etype (N) to the actual type found where Typ was expected).
1537 else
1541 -- If this is a call to a function that renames a predefined equality,
1542 -- the renaming declaration provides a type that must be used to
1543 -- resolve the operands. This must be done now because resolution of
1544 -- the equality node will not resolve any remaining ambiguity, and it
1545 -- assumes that the first operand is not overloaded.
1550 then
1558 -- Do rewrite setting Comes_From_Source on the result if the original
1559 -- call came from source. Although it is not strictly the case that the
1560 -- operator as such comes from the source, logically it corresponds
1561 -- exactly to the function call in the source, so it should be marked
1562 -- this way (e.g. to make sure that validity checks work fine).
1564 declare
1566 begin
1571 -- If this is an arithmetic operator and the result type is private,
1572 -- the operands and the result must be wrapped in conversion to
1573 -- expose the underlying numeric type and expand the proper checks,
1574 -- e.g. on division.
1578 when N_Op_Add
1579 | N_Op_Divide
1580 | N_Op_Expon
1581 | N_Op_Mod
1582 | N_Op_Multiply
1583 | N_Op_Rem
1584 | N_Op_Subtract
1585 =>
1588 when N_Op_Abs
1589 | N_Op_Minus
1590 | N_Op_Plus
1591 =>
1597 else
1601 -- If in ASIS_Mode, propagate operand types to original actuals of
1602 -- function call, which would otherwise not be fully resolved. If
1603 -- the call has already been constant-folded, nothing to do. We
1604 -- relocate the operand nodes rather than copy them, to preserve
1605 -- original_node pointers, given that the operands themselves may
1606 -- have been rewritten. If the call was itself a rewriting of an
1607 -- operator node, nothing to do.
1609 if ASIS_Mode
1612 then
1613 declare
1621 begin
1626 -- If the original call has named associations, replace the
1627 -- explicit actual parameter in the association with the proper
1628 -- resolved operand.
1633 then
1636 else
1641 else
1648 then
1651 else
1656 else
1660 else
1664 else
1674 -------------------
1675 -- Operator_Kind --
1676 -------------------
1678 function Operator_Kind
1681 is
1684 begin
1685 -- Use CASE statement or array???
1722 else
1726 -- Unary operators
1728 else
1737 else
1745 ----------------------------
1746 -- Preanalyze_And_Resolve --
1747 ----------------------------
1752 begin
1756 -- Normally, we suppress all checks for this preanalysis. There is no
1757 -- point in processing them now, since they will be applied properly
1758 -- and in the proper location when the default expressions reanalyzed
1759 -- and reexpanded later on. We will also have more information at that
1760 -- point for possible suppression of individual checks.
1762 -- However, in SPARK mode, most expansion is suppressed, and this
1763 -- later reanalysis and reexpansion may not occur. SPARK mode does
1764 -- require the setting of checking flags for proof purposes, so we
1765 -- do the SPARK preanalysis without suppressing checks.
1767 -- This special handling for SPARK mode is required for example in the
1768 -- case of Ada 2012 constructs such as quantified expressions, which are
1769 -- expanded in two separate steps.
1773 else
1777 Expander_Mode_Restore;
1781 -- Version without context type
1786 begin
1793 Expander_Mode_Restore;
1797 ----------------------------------
1798 -- Replace_Actual_Discriminants --
1799 ----------------------------------
1806 -- Comment needed???
1808 -------------------
1809 -- Process_Discr --
1810 -------------------
1815 begin
1821 then
1837 -- Start of processing for Replace_Actual_Discriminants
1839 begin
1853 else
1858 -------------
1859 -- Resolve --
1860 -------------
1876 -- Determine whether a node comes from a predefined library unit or
1877 -- Standard.
1880 -- Try and fix up a literal so that it matches its expected type. New
1881 -- literals are manufactured if necessary to avoid cascaded errors.
1884 -- Additional diagnostics when an ambiguous call has an ambiguous
1885 -- argument (typically a controlling actual).
1888 -- Called when attempt at resolving current expression fails
1890 ------------------------------------
1891 -- Comes_From_Predefined_Lib_Unit --
1892 -------------------------------------
1895 begin
1896 return
1898 or else Is_Predefined_File_Name
1902 --------------------
1903 -- Patch_Up_Value --
1904 --------------------
1907 begin
1924 then
1929 Char_Literal_Value =>
1945 -------------------------------
1946 -- Report_Ambiguous_Argument --
1947 -------------------------------
1954 begin
1958 then
1961 -- Could use comments on what is going on here???
1969 else
1978 -----------------------
1979 -- Resolution_Failed --
1980 -----------------------
1983 begin
1986 -- Set the type to the desired one to minimize cascaded errors. Note
1987 -- that this is an approximation and does not work in all cases.
1994 -- The caller will return without calling the expander, so we need
1995 -- to set the analyzed flag. Note that it is fine to set Analyzed
1996 -- to True even if we are in the middle of a shallow analysis,
1997 -- (see the spec of sem for more details) since this is an error
1998 -- situation anyway, and there is no point in repeating the
1999 -- analysis later (indeed it won't work to repeat it later, since
2000 -- we haven't got a clear resolution of which entity is being
2001 -- referenced.)
2007 -- Start of processing for Resolve
2009 begin
2014 -- Access attribute on remote subprogram cannot be used for a non-remote
2015 -- access-to-subprogram type.
2019 Name_Unrestricted_Access,
2020 Name_Unchecked_Access)
2026 then
2027 Error_Msg_N
2033 -- If the context is a Remote_Access_To_Subprogram, access attributes
2034 -- must be resolved with the corresponding fat pointer. There is no need
2035 -- to check for the attribute name since the return type of an
2036 -- attribute is never a remote type.
2041 then
2042 declare
2050 begin
2051 -- Check that Typ is a remote access-to-subprogram type
2055 -- Prefix (N) must statically denote a remote subprogram
2056 -- declared in a package specification.
2060 Attr = Attribute_Unrestricted_Access
2061 then
2076 or else
2078 then
2080 Error_Msg_N
2082 N);
2085 -- If we are generating code in distributed mode, perform
2086 -- semantic checks against corresponding remote entities.
2088 if Expander_Active
2090 then
2091 Check_Subtype_Conformant
2093 Old_Id => Designated_Type
2119 then
2124 -- Return if already analyzed
2131 -- Any case of Any_Type as the Etype value means that we had a
2132 -- previous error.
2141 -- The resolution of an Expression_With_Actions is determined by
2142 -- its Expression.
2150 -- If not overloaded, then we know the type, and all that needs doing
2151 -- is to check that this type is compatible with the context.
2157 -- In the overloaded case, we must select the interpretation that
2158 -- is compatible with the context (i.e. the type passed to Resolve)
2160 else
2161 -- Loop through possible interpretations
2170 -- We are only interested in interpretations that are compatible
2171 -- with the expected type, any other interpretations are ignored.
2176 Write_Eol;
2179 else
2180 -- Skip the current interpretation if it is disabled by an
2181 -- abstract operator. This action is performed only when the
2182 -- type against which we are resolving is the same as the
2183 -- type of the interpretation.
2190 then
2198 -- First matching interpretation
2206 -- Matching interpretation that is not the first, maybe an
2207 -- error, but there are some cases where preference rules are
2208 -- used to choose between the two possibilities. These and
2209 -- some more obscure cases are handled in Disambiguate.
2211 else
2212 -- If the current statement is part of a predefined library
2213 -- unit, then all interpretations which come from user level
2214 -- packages should not be considered. Check previous and
2215 -- current one.
2223 -- Previous interpretation must be discarded
2233 -- Otherwise apply further disambiguation steps
2238 -- Disambiguation has succeeded. Skip the remaining
2239 -- interpretations.
2249 else
2250 -- Before we issue an ambiguity complaint, check for the
2251 -- case of a subprogram call where at least one of the
2252 -- arguments is Any_Type, and if so suppress the message,
2253 -- since it is a cascaded error. This can also happen for
2254 -- a generalized indexing operation.
2259 then
2260 declare
2264 begin
2280 Write_Eol;
2293 then
2298 then
2302 -- Not that special case, so issue message using the flag
2303 -- Ambiguous to control printing of the header message
2304 -- only at the start of an ambiguous set.
2309 then
2310 Error_Msg_N
2313 else
2314 Error_Msg_NE -- CODEFIX
2322 Error_Msg_N
2324 else
2325 Error_Msg_N -- CODEFIX
2331 then
2332 Report_Ambiguous_Argument;
2338 -- By default, the error message refers to the candidate
2339 -- interpretation. But if it is a predefined operator, it
2340 -- is implicitly declared at the declaration of the type
2341 -- of the operand. Recover the sloc of that declaration
2342 -- for the error message.
2348 Standard_Standard
2349 then
2354 then
2362 Standard_Standard
2363 then
2368 then
2372 -- If this is an indirect call, use the subprogram_type
2373 -- in the message, to have a meaningful location. Also
2374 -- indicate if this is an inherited operation, created
2375 -- by a type declaration.
2380 then
2382 Error_Msg_Sloc :=
2384 else
2391 then
2392 -- Special-case the message for universal_fixed
2393 -- operators, which are not declared with the type
2394 -- of the operand, but appear forever in Standard.
2398 then
2399 Error_Msg_N
2402 else
2403 Error_Msg_N
2407 elsif
2409 then
2410 Error_Msg_N
2412 else
2413 Error_Msg_N -- CODEFIX
2420 -- We have a matching interpretation, Expr_Type is the type
2421 -- from this interpretation, and Seen is the entity.
2423 -- For an operator, just set the entity name. The type will be
2424 -- set by the specific operator resolution routine.
2439 -- AI05-0139-2: Expression is overloaded because type has
2440 -- implicit dereference. If type matches context, no implicit
2441 -- dereference is involved.
2452 then
2453 -- If the node is a general indexing, the dereference is
2454 -- is inserted when resolving the rewritten form, else
2455 -- insert it now.
2459 then
2463 -- For an explicit dereference, attribute reference, range,
2464 -- short-circuit form (which is not an operator node), or call
2465 -- with a name that is an explicit dereference, there is
2466 -- nothing to be done at this point.
2469 N_And_Then,
2470 N_Explicit_Dereference,
2471 N_Identifier,
2472 N_Indexed_Component,
2473 N_Or_Else,
2474 N_Range,
2475 N_Selected_Component,
2476 N_Slice)
2478 then
2481 -- For procedure or function calls, set the type of the name,
2482 -- and also the entity pointer for the prefix.
2486 then
2493 then
2498 -- For all other cases, just set the type of the Name
2500 else
2508 -- Move to next interpretation
2516 -- At this stage Found indicates whether or not an acceptable
2517 -- interpretation exists. If not, then we have an error, except that if
2518 -- the context is Any_Type as a result of some other error, then we
2519 -- suppress the error report.
2524 -- If type we are looking for is Void, then this is the procedure
2525 -- call case, and the error is simply that what we gave is not a
2526 -- procedure name (we think of procedure calls as expressions with
2527 -- types internally, but the user doesn't think of them this way).
2531 -- Special case message if function used as a procedure
2536 then
2537 Error_Msg_NE
2541 -- Otherwise give general message (not clear what cases this
2542 -- covers, but no harm in providing for them).
2544 else
2550 -- Otherwise we do have a subexpression with the wrong type
2552 -- Check for the case of an allocator which uses an access type
2553 -- instead of the designated type. This is a common error and we
2554 -- specialize the message, posting an error on the operand of the
2555 -- allocator, complaining that we expected the designated type of
2556 -- the allocator.
2562 then
2566 -- Check for view mismatch on Null in instances, for which the
2567 -- view-swapping mechanism has no identifier.
2573 then
2578 -- Check for an aggregate. Sometimes we can get bogus aggregates
2579 -- from misuse of parentheses, and we are about to complain about
2580 -- the aggregate without even looking inside it.
2582 -- Instead, if we have an aggregate of type Any_Composite, then
2583 -- analyze and resolve the component fields, and then only issue
2584 -- another message if we get no errors doing this (otherwise
2585 -- assume that the errors in the aggregate caused the problem).
2589 then
2590 -- Disable expansion in any case. If there is a type mismatch
2591 -- it may be fatal to try to expand the aggregate. The flag
2592 -- would otherwise be set to false when the error is posted.
2596 declare
2598 -- Check one aggregate, and set Found to True if we have a
2599 -- definite error in any of its elements
2602 -- Check one element of aggregate and set Found to True if
2603 -- we definitely have an error in the element.
2605 ----------------
2606 -- Check_Aggr --
2607 ----------------
2612 begin
2625 -- If this is a default-initialized component, then
2626 -- there is nothing to check. The box will be
2627 -- replaced by the appropriate call during late
2628 -- expansion.
2632 then
2641 ----------------
2642 -- Check_Elmt --
2643 ----------------
2646 begin
2647 -- If we have a nested aggregate, go inside it (to
2648 -- attempt a naked analyze-resolve of the aggregate can
2649 -- cause undesirable cascaded errors). Do not resolve
2650 -- expression if it needs a type from context, as for
2651 -- integer * fixed expression.
2656 else
2661 then
2671 begin
2676 -- Looks like we have a type error, but check for special case
2677 -- of Address wanted, integer found, with the configuration pragma
2678 -- Allow_Integer_Address active. If we have this case, introduce
2679 -- an unchecked conversion to allow the integer expression to be
2680 -- treated as an Address. The reverse case of integer wanted,
2681 -- Address found, is treated in an analogous manner.
2688 -- Under relaxed RM semantics silently replace occurrences of null
2689 -- by System.Address_Null.
2697 -- That special Allow_Integer_Address check did not apply, so we
2698 -- have a real type error. If an error message was issued already,
2699 -- Found got reset to True, so if it's still False, issue standard
2700 -- Wrong_Type message.
2704 declare
2707 begin
2713 -- Protected operation: retrieve operation name
2717 else
2722 Error_Msg_NE
2728 declare
2732 begin
2739 Error_Msg_NE
2745 else
2749 else
2755 Resolution_Failed;
2758 -- Test if we have more than one interpretation for the context
2761 Resolution_Failed;
2764 -- Only one intepretation
2766 else
2767 -- In Ada 2005, if we have something like "X : T := 2 + 2;", where
2768 -- the "+" on T is abstract, and the operands are of universal type,
2769 -- the above code will have (incorrectly) resolved the "+" to the
2770 -- universal one in Standard. Therefore check for this case and give
2771 -- an error. We can't do this earlier, because it would cause legal
2772 -- cases to get errors (when some other type has an abstract "+").
2778 then
2783 then
2784 Error_Msg_NE
2793 -- Here we have an acceptable interpretation for the context
2795 -- Propagate type information and normalize tree for various
2796 -- predefined operations. If the context only imposes a class of
2797 -- types, rather than a specific type, propagate the actual type
2798 -- downward.
2804 Typ = Any_Discrete
2805 then
2808 -- Any_Fixed is legal in a real context only if a specific fixed-
2809 -- point type is imposed. If Norman Cohen can be confused by this,
2810 -- it deserves a separate message.
2814 then
2821 -- A user-defined operator is transformed into a function call at
2822 -- this point, so that further processing knows that operators are
2823 -- really operators (i.e. are predefined operators). User-defined
2824 -- operators that are intrinsic are just renamings of the predefined
2825 -- ones, and need not be turned into calls either, but if they rename
2826 -- a different operator, we must transform the node accordingly.
2827 -- Instantiations of Unchecked_Conversion are intrinsic but are
2828 -- treated as functions, even if given an operator designator.
2833 then
2838 and then
2840 N_Subprogram_Renaming_Declaration
2841 then
2844 -- If the node is rewritten, it will be fully resolved in
2845 -- Rewrite_Renamed_Operator.
2854 when N_Aggregate =>
2855 Resolve_Aggregate (N, Ctx_Type);
2857 when N_Allocator =>
2858 Resolve_Allocator (N, Ctx_Type);
2860 when N_Short_Circuit =>
2861 Resolve_Short_Circuit (N, Ctx_Type);
2863 when N_Attribute_Reference =>
2864 Resolve_Attribute (N, Ctx_Type);
2866 when N_Case_Expression =>
2867 Resolve_Case_Expression (N, Ctx_Type);
2869 when N_Character_Literal =>
2870 Resolve_Character_Literal (N, Ctx_Type);
2872 when N_Expanded_Name =>
2873 Resolve_Entity_Name (N, Ctx_Type);
2875 when N_Explicit_Dereference =>
2876 Resolve_Explicit_Dereference (N, Ctx_Type);
2878 when N_Expression_With_Actions =>
2879 Resolve_Expression_With_Actions (N, Ctx_Type);
2881 when N_Extension_Aggregate =>
2882 Resolve_Extension_Aggregate (N, Ctx_Type);
2884 when N_Function_Call =>
2885 Resolve_Call (N, Ctx_Type);
2887 when N_Identifier =>
2888 Resolve_Entity_Name (N, Ctx_Type);
2890 when N_If_Expression =>
2891 Resolve_If_Expression (N, Ctx_Type);
2893 when N_Indexed_Component =>
2894 Resolve_Indexed_Component (N, Ctx_Type);
2896 when N_Integer_Literal =>
2897 Resolve_Integer_Literal (N, Ctx_Type);
2899 when N_Membership_Test =>
2900 Resolve_Membership_Op (N, Ctx_Type);
2902 when N_Null =>
2903 Resolve_Null (N, Ctx_Type);
2905 when N_Op_And
2906 | N_Op_Or
2907 | N_Op_Xor
2908 =>
2909 Resolve_Logical_Op (N, Ctx_Type);
2911 when N_Op_Eq
2912 | N_Op_Ne
2913 =>
2914 Resolve_Equality_Op (N, Ctx_Type);
2916 when N_Op_Ge
2917 | N_Op_Gt
2918 | N_Op_Le
2919 | N_Op_Lt
2920 =>
2921 Resolve_Comparison_Op (N, Ctx_Type);
2923 when N_Op_Not =>
2924 Resolve_Op_Not (N, Ctx_Type);
2926 when N_Op_Add
2927 | N_Op_Divide
2928 | N_Op_Mod
2929 | N_Op_Multiply
2930 | N_Op_Rem
2931 | N_Op_Subtract
2932 =>
2933 Resolve_Arithmetic_Op (N, Ctx_Type);
2935 when N_Op_Concat =>
2936 Resolve_Op_Concat (N, Ctx_Type);
2938 when N_Op_Expon =>
2939 Resolve_Op_Expon (N, Ctx_Type);
2941 when N_Op_Abs
2942 | N_Op_Minus
2943 | N_Op_Plus
2944 =>
2945 Resolve_Unary_Op (N, Ctx_Type);
2947 when N_Op_Shift =>
2948 Resolve_Shift (N, Ctx_Type);
2950 when N_Procedure_Call_Statement =>
2951 Resolve_Call (N, Ctx_Type);
2953 when N_Operator_Symbol =>
2954 Resolve_Operator_Symbol (N, Ctx_Type);
2956 when N_Qualified_Expression =>
2957 Resolve_Qualified_Expression (N, Ctx_Type);
2959 -- Why is the following null, needs a comment ???
2961 when N_Quantified_Expression =>
2962 null;
2964 when N_Raise_Expression =>
2965 Resolve_Raise_Expression (N, Ctx_Type);
2967 when N_Raise_xxx_Error =>
2968 Set_Etype (N, Ctx_Type);
2970 when N_Range =>
2971 Resolve_Range (N, Ctx_Type);
2973 when N_Real_Literal =>
2974 Resolve_Real_Literal (N, Ctx_Type);
2976 when N_Reference =>
2977 Resolve_Reference (N, Ctx_Type);
2979 when N_Selected_Component =>
2980 Resolve_Selected_Component (N, Ctx_Type);
2982 when N_Slice =>
2983 Resolve_Slice (N, Ctx_Type);
2985 when N_String_Literal =>
2986 Resolve_String_Literal (N, Ctx_Type);
2988 when N_Type_Conversion =>
2989 Resolve_Type_Conversion (N, Ctx_Type);
2991 when N_Unchecked_Expression =>
2992 Resolve_Unchecked_Expression (N, Ctx_Type);
2994 when N_Unchecked_Type_Conversion =>
2995 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
2996 end case;
2998 -- Ada 2012 (AI05-0149): Apply an (implicit) conversion to an
2999 -- expression of an anonymous access type that occurs in the context
3000 -- of a named general access type, except when the expression is that
3001 -- of a membership test. This ensures proper legality checking in
3002 -- terms of allowed conversions (expressions that would be illegal to
3003 -- convert implicitly are allowed in membership tests).
3005 if Ada_Version >= Ada_2012
3006 and then Ekind (Ctx_Type) = E_General_Access_Type
3007 and then Ekind (Etype (N)) = E_Anonymous_Access_Type
3008 and then Nkind (Parent (N)) not in N_Membership_Test
3009 then
3010 Rewrite (N, Convert_To (Ctx_Type, Relocate_Node (N)));
3011 Analyze_And_Resolve (N, Ctx_Type);
3012 end if;
3014 -- If the subexpression was replaced by a non-subexpression, then
3015 -- all we do is to expand it. The only legitimate case we know of
3016 -- is converting procedure call statement to entry call statements,
3017 -- but there may be others, so we are making this test general.
3019 if Nkind (N) not in N_Subexpr then
3020 Debug_A_Exit ("resolving ", N, " (done)");
3021 Expand (N);
3022 return;
3023 end if;
3025 -- The expression is definitely NOT overloaded at this point, so
3026 -- we reset the Is_Overloaded flag to avoid any confusion when
3027 -- reanalyzing the node.
3029 Set_Is_Overloaded (N, False);
3031 -- Freeze expression type, entity if it is a name, and designated
3032 -- type if it is an allocator (RM 13.14(10,11,13)).
3034 -- Now that the resolution of the type of the node is complete, and
3035 -- we did not detect an error, we can expand this node. We skip the
3036 -- expand call if we are in a default expression, see section
3037 -- "Handling of Default Expressions" in Sem spec.
3039 Debug_A_Exit ("resolving ", N, " (done)");
3041 -- We unconditionally freeze the expression, even if we are in
3042 -- default expression mode (the Freeze_Expression routine tests this
3043 -- flag and only freezes static types if it is set).
3045 -- Ada 2012 (AI05-177): The declaration of an expression function
3046 -- does not cause freezing, but we never reach here in that case.
3047 -- Here we are resolving the corresponding expanded body, so we do
3048 -- need to perform normal freezing.
3050 Freeze_Expression (N);
3052 -- Now we can do the expansion
3054 Expand (N);
3055 end if;
3056 end Resolve;
3058 -------------
3059 -- Resolve --
3060 -------------
3062 -- Version with check(s) suppressed
3064 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
3065 begin
3066 if Suppress = All_Checks then
3067 declare
3068 Sva : constant Suppress_Array := Scope_Suppress.Suppress;
3069 begin
3070 Scope_Suppress.Suppress := (others => True);
3071 Resolve (N, Typ);
3072 Scope_Suppress.Suppress := Sva;
3073 end;
3075 else
3076 declare
3077 Svg : constant Boolean := Scope_Suppress.Suppress (Suppress);
3078 begin
3079 Scope_Suppress.Suppress (Suppress) := True;
3080 Resolve (N, Typ);
3081 Scope_Suppress.Suppress (Suppress) := Svg;
3082 end;
3083 end if;
3084 end Resolve;
3086 -------------
3087 -- Resolve --
3088 -------------
3090 -- Version with implicit type
3092 procedure Resolve (N : Node_Id) is
3093 begin
3094 Resolve (N, Etype (N));
3095 end Resolve;
3097 ---------------------
3098 -- Resolve_Actuals --
3099 ---------------------
3101 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
3102 Loc : constant Source_Ptr := Sloc (N);
3103 A : Node_Id;
3104 A_Id : Entity_Id;
3105 A_Typ : Entity_Id;
3106 F : Entity_Id;
3107 F_Typ : Entity_Id;
3108 Prev : Node_Id := Empty;
3109 Orig_A : Node_Id;
3110 Real_F : Entity_Id;
3112 Real_Subp : Entity_Id;
3113 -- If the subprogram being called is an inherited operation for
3114 -- a formal derived type in an instance, Real_Subp is the subprogram
3115 -- that will be called. It may have different formal names than the
3116 -- operation of the formal in the generic, so after actual is resolved
3117 -- the name of the actual in a named association must carry the name
3118 -- of the actual of the subprogram being called.
3120 procedure Check_Aliased_Parameter;
3121 -- Check rules on aliased parameters and related accessibility rules
3122 -- in (RM 3.10.2 (10.2-10.4)).
3124 procedure Check_Argument_Order;
3125 -- Performs a check for the case where the actuals are all simple
3126 -- identifiers that correspond to the formal names, but in the wrong
3127 -- order, which is considered suspicious and cause for a warning.
3129 procedure Check_Prefixed_Call;
3130 -- If the original node is an overloaded call in prefix notation,
3132 -- Try_Object_Operation has already verified that there is a valid
3133 -- interpretation, but the form of the actual can only be determined
3134 -- once the primitive operation is identified.
3137 -- Emit an error concerning the illegal usage of an effectively volatile
3138 -- object in interfering context (SPARK RM 7.13(12)).
3141 -- If the actual is missing in a call, insert in the actuals list
3142 -- an instance of the default expression. The insertion is always
3143 -- a named association.
3145 procedure Property_Error
3149 -- Emit an error concerning variable Var with entity Var_Id that has
3150 -- enabled property Prop_Nam when it acts as an actual parameter in a
3151 -- call and the corresponding formal parameter is of mode IN.
3154 -- Check whether T1 and T2, or their full views, are derived from a
3155 -- common type. Used to enforce the restrictions on array conversions
3156 -- of AI95-00246.
3159 -- Predicate to determine whether an actual that is a concatenation
3160 -- will be evaluated statically and does not need a transient scope.
3161 -- This must be determined before the actual is resolved and expanded
3162 -- because if needed the transient scope must be introduced earlier.
3164 -----------------------------
3165 -- Check_Aliased_Parameter --
3166 -----------------------------
3171 begin
3179 else
3186 -- In a generic body assume the worst for generic formals:
3187 -- they can have a constrained partial view (AI05-041).
3193 then
3196 else
3201 else
3213 then
3221 then
3222 Error_Msg_N
3228 --------------------------
3229 -- Check_Argument_Order --
3230 --------------------------
3233 begin
3234 -- Nothing to do if no parameters, or original node is neither a
3235 -- function call nor a procedure call statement (happens in the
3236 -- operator-transformed-to-function call case), or the call does
3237 -- not come from source, or this warning is off.
3239 if not Warn_On_Parameter_Order
3243 then
3247 declare
3250 begin
3251 -- Nothing to do if only one parameter
3257 -- Here if at least two arguments
3259 declare
3265 -- Set True if an out of order case is found
3267 begin
3268 -- Collect identifier names of actuals, fail if any actual is
3269 -- not a simple identifier, and record max length of name.
3275 else
3281 -- If we got this far, all actuals are identifiers and the list
3282 -- of their names is stored in the Actuals array.
3287 -- If we ran out of formals, that's odd, probably an error
3288 -- which will be detected elsewhere, but abandon the search.
3294 -- If name matches and is in order OK
3299 else
3300 -- If no match, see if it is elsewhere in list and if so
3301 -- flag potential wrong order if type is compatible.
3305 and then
3307 then
3313 -- No match
3321 -- If Formals left over, also probably an error, skip warning
3327 -- Here we give the warning if something was out of order
3330 Error_Msg_N
3337 -------------------------
3338 -- Check_Prefixed_Call --
3339 -------------------------
3348 begin
3349 -- Check whether the call is a prefixed call, with or without
3350 -- additional actuals.
3353 or else
3359 then
3362 then
3363 -- Introduce dereference on object in prefix
3365 New_A :=
3373 then
3374 -- Introduce an implicit 'Access in prefix
3377 Error_Msg_NE
3393 ---------------------------------------
3394 -- Flag_Effectively_Volatile_Objects --
3395 ---------------------------------------
3399 -- Determine whether arbitrary node N denotes an effectively volatile
3400 -- object and if it does, emit an error.
3402 -----------------
3403 -- Flag_Object --
3404 -----------------
3409 begin
3410 -- Do not consider nested function calls because they have already
3411 -- been processed during their own resolution.
3423 then
3424 Error_Msg_N
3436 -- Start of processing for Flag_Effectively_Volatile_Objects
3438 begin
3442 --------------------
3443 -- Insert_Default --
3444 --------------------
3450 begin
3451 -- Missing argument in call, nothing to insert
3456 else
3457 -- Note that we do a full New_Copy_Tree, so that any associated
3458 -- Itypes are properly copied. This may not be needed any more,
3459 -- but it does no harm as a safety measure. Defaults of a generic
3460 -- formal may be out of bounds of the corresponding actual (see
3461 -- cc1311b) and an additional check may be required.
3463 Actval :=
3464 New_Copy_Tree
3469 -- Propagate dimension information, if any.
3475 then
3481 then
3484 then
3485 -- If default is a real literal, do not introduce a
3486 -- conversion whose effect may depend on the run-time
3487 -- size of universal real.
3491 else
3502 -- Resolve aggregates with their base type, to avoid scope
3503 -- anomalies: the subtype was first built in the subprogram
3504 -- declaration, and the current call may be nested.
3508 else
3512 else
3515 -- See note above concerning aggregates
3519 then
3522 -- Resolve entities with their own type, which may differ from
3523 -- the type of a reference in a generic context (the view
3524 -- swapping mechanism did not anticipate the re-analysis of
3525 -- default values in calls).
3530 else
3535 -- If default is a tag indeterminate function call, propagate tag
3536 -- to obtain proper dispatching.
3540 then
3545 -- If the default expression raises constraint error, then just
3546 -- silently replace it with an N_Raise_Constraint_Error node, since
3547 -- we already gave the warning on the subprogram spec. If node is
3548 -- already a Raise_Constraint_Error leave as is, to prevent loops in
3549 -- the warnings removal machinery.
3553 then
3561 Assoc :=
3566 -- Case of insertion is first named actual
3570 then
3577 else
3581 else
3585 -- Case of insertion is not first named actual
3587 else
3588 Set_Next_Named_Actual
3600 --------------------
3601 -- Property_Error --
3602 --------------------
3604 procedure Property_Error
3608 is
3609 begin
3611 Error_Msg_NE
3617 -------------------
3618 -- Same_Ancestor --
3619 -------------------
3625 begin
3628 then
3634 then
3641 --------------------------
3642 -- Static_Concatenation --
3643 --------------------------
3646 begin
3653 -- Concatenation is static when both operands are static and
3654 -- the concatenation operator is a predefined one.
3657 and then
3659 and then
3664 declare
3666 begin
3669 and then
3673 else
3679 -- Start of processing for Resolve_Actuals
3681 begin
3682 Check_Argument_Order;
3686 and then In_Instance
3689 then
3691 else
3696 Check_Prefixed_Call;
3710 -- If we have an error in any actual or formal, indicated by a type
3711 -- of Any_Type, then abandon resolution attempt, and set result type
3712 -- to Any_Type. Skip this if the actual is a Raise_Expression, whose
3713 -- type is imposed from context.
3717 then
3724 -- Case where actual is present
3726 -- If the actual is an entity, generate a reference to it now. We
3727 -- do this before the actual is resolved, because a formal of some
3728 -- protected subprogram, or a task discriminant, will be rewritten
3729 -- during expansion, and the source entity reference may be lost.
3734 then
3740 then
3747 -- RM 6.4.1(12): For an out parameter that is passed by
3748 -- copy, the formal parameter object is created, and:
3750 -- * For an access type, the formal parameter is initialized
3751 -- from the value of the actual, without checking that the
3752 -- value satisfies any constraint, any predicate, or any
3753 -- exclusion of the null value.
3755 -- * For a scalar type that has the Default_Value aspect
3756 -- specified, the formal parameter is initialized from the
3757 -- value of the actual, without checking that the value
3758 -- satisfies any constraint or any predicate.
3759 -- I do not understand why this case is included??? this is
3760 -- not a case where an OUT parameter is treated as IN OUT.
3762 -- * For a composite type with discriminants or that has
3763 -- implicit initial values for any subcomponents, the
3764 -- behavior is as for an in out parameter passed by copy.
3766 -- Hence for these cases we generate the read reference now
3767 -- (the write reference will be generated later by
3768 -- Note_Possible_Modification).
3771 and then
3773 or else
3775 and then
3777 or else
3780 or else Is_Partially_Initialized_Type
3782 then
3792 then
3793 -- If style checking mode on, check match of formal name
3801 -- If the formal is Out or In_Out, do not resolve and expand the
3802 -- conversion, because it is subsequently expanded into explicit
3803 -- temporaries and assignments. However, the object of the
3804 -- conversion can be resolved. An exception is the case of tagged
3805 -- type conversion with a class-wide actual. In that case we want
3806 -- the tag check to occur and no temporary will be needed (no
3807 -- representation change can occur) and the parameter is passed by
3808 -- reference, so we go ahead and resolve the type conversion.
3809 -- Another exception is the case of reference to component or
3810 -- subcomponent of a bit-packed array, in which case we want to
3811 -- defer expansion to the point the in and out assignments are
3812 -- performed.
3817 then
3820 then
3821 -- In a view conversion, the conversion must be legal in
3822 -- both directions, and thus both component types must be
3823 -- aliased, or neither (4.6 (8)).
3825 -- The extra rule in 4.6 (24.9.2) seems unduly restrictive:
3826 -- the privacy requirement should not apply to generic
3827 -- types, and should be checked in an instance. ARG query
3828 -- is in order ???
3832 then
3833 Error_Msg_N
3837 -- Comment here??? what set of cases???
3839 elsif
3841 then
3842 -- Check view conv between unrelated by ref array types
3846 then
3847 Error_Msg_N
3851 -- In Ada 2005 mode, check view conversion component
3852 -- type cannot be private, tagged, or volatile. Note
3853 -- that we only apply this to source conversions. The
3854 -- generated code can contain conversions which are
3855 -- not subject to this test, and we cannot extract the
3856 -- component type in such cases since it is not present.
3860 then
3861 declare
3863 Component_Type
3865 begin
3870 then
3871 Error_Msg_N
3882 -- Resolve expression if conversion is all OK
3887 then
3891 -- If the actual is a function call that returns a limited
3892 -- unconstrained object that needs finalization, create a
3893 -- transient scope for it, so that it can receive the proper
3894 -- finalization list.
3899 and then Expander_Active
3901 then
3905 -- A small optimization: if one of the actuals is a concatenation
3906 -- create a block around a procedure call to recover stack space.
3907 -- This alleviates stack usage when several procedure calls in
3908 -- the same statement list use concatenation. We do not perform
3909 -- this wrapping for code statements, where the argument is a
3910 -- static string, and we want to preserve warnings involving
3911 -- sequences of such statements.
3915 and then Expander_Active
3916 and then
3920 then
3924 else
3928 and then
3931 then
3932 Error_Msg_N
3945 -- (Ada 2005: AI-251): If the actual is an allocator whose
3946 -- directly designated type is a class-wide interface, we build
3947 -- an anonymous access type to use it as the type of the
3948 -- allocator. Later, when the subprogram call is expanded, if
3949 -- the interface has a secondary dispatch table the expander
3950 -- will add a type conversion to force the correct displacement
3951 -- of the pointer.
3954 declare
3960 begin
3963 then
3966 Set_Directly_Designated_Type
3971 -- Ada 2005, AI-162:If the actual is an allocator, the
3972 -- innermost enclosing statement is the master of the
3973 -- created object. This needs to be done with expansion
3974 -- enabled only, otherwise the transient scope will not
3975 -- be removed in the expansion of the wrapped construct.
3978 and then Expander_Active
3979 then
3989 -- (Ada 2005): The call may be to a primitive operation of a
3990 -- tagged synchronized type, declared outside of the type. In
3991 -- this case the controlling actual must be converted to its
3992 -- corresponding record type, which is the formal type. The
3993 -- actual may be a subtype, either because of a constraint or
3994 -- because it is a generic actual, so use base type to locate
3995 -- concurrent type.
4002 then
4003 -- If the actual is overloaded, look for an interpretation
4004 -- that has a synchronized type.
4009 else
4010 declare
4014 begin
4019 then
4029 declare
4032 begin
4035 else
4039 -- Tagged synchronized type (case 1): the actual is a
4040 -- concurrent type.
4044 then
4046 Unchecked_Convert_To
4050 -- Tagged synchronized type (case 2): the formal is a
4051 -- concurrent type.
4054 and then Present
4059 then
4062 -- Common case
4064 else
4069 -- Not a synchronized operation
4071 else
4079 -- An actual cannot be an untagged formal incomplete type
4084 then
4085 Error_Msg_N
4091 N_Procedure_Call_Statement)
4092 then
4093 -- In formal mode, check that actual parameters matching
4094 -- formals of tagged types are objects (or ancestor type
4095 -- conversions of objects), not general expressions.
4102 declare
4107 begin
4109 Check_SPARK_05_Restriction
4112 -- In formal mode, the only view conversions are those
4113 -- involving ancestor conversion of an extended type.
4115 elsif not
4121 then
4122 if Ekind_In
4124 then
4125 Check_SPARK_05_Restriction
4128 else
4129 Check_SPARK_05_Restriction
4133 else
4138 else
4142 -- In formal mode, the only view conversions are those
4143 -- involving ancestor conversion of an extended type.
4147 then
4148 Check_SPARK_05_Restriction
4154 -- has warnings suppressed, then we reset Never_Set_In_Source for
4155 -- the calling entity. The reason for this is to catch cases like
4156 -- GNAT.Spitbol.Patterns.Vstring_Var where the called subprogram
4157 -- uses trickery to modify an IN parameter.
4164 then
4168 -- Perform error checks for IN and IN OUT parameters
4172 -- Check unset reference. For scalar parameters, it is clearly
4173 -- wrong to pass an uninitialized value as either an IN or
4174 -- IN-OUT parameter. For composites, it is also clearly an
4175 -- error to pass a completely uninitialized value as an IN
4176 -- parameter, but the case of IN OUT is trickier. We prefer
4177 -- not to give a warning here. For example, suppose there is
4178 -- a routine that sets some component of a record to False.
4179 -- It is perfectly reasonable to make this IN-OUT and allow
4180 -- either initialized or uninitialized records to be passed
4181 -- in this case.
4183 -- For partially initialized composite values, we also avoid
4184 -- warnings, since it is quite likely that we are passing a
4185 -- partially initialized value and only the initialized fields
4186 -- will in fact be read in the subprogram.
4191 then
4195 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
4196 -- actual to a nested call, since this constitutes a reading of
4197 -- the parameter, which is not allowed.
4202 then
4207 -- Case of OUT or IN OUT parameter
4211 -- For an Out parameter, check for useless assignment. Note
4212 -- that we can't set Last_Assignment this early, because we may
4213 -- kill current values in Resolve_Call, and that call would
4214 -- clobber the Last_Assignment field.
4216 -- Note: call Warn_On_Useless_Assignment before doing the check
4217 -- below for Is_OK_Variable_For_Out_Formal so that the setting
4218 -- of Referenced_As_LHS/Referenced_As_Out_Formal properly
4219 -- reflects the last assignment, not this one.
4226 then
4231 -- Validate the form of the actual. Note that the call to
4232 -- Is_OK_Variable_For_Out_Formal generates the required
4233 -- reference in this case.
4235 -- A call to an initialization procedure for an aggregate
4236 -- component may initialize a nested component of a constant
4237 -- designated object. In this context the object is variable.
4241 then
4247 then
4248 Error_Msg_N
4253 Error_Msg_N
4260 -- What's the following about???
4264 else
4265 Kill_All_Checks;
4274 -- Apply appropriate constraint/predicate checks for IN [OUT] case
4278 -- Apply predicate tests except in certain special cases. Note
4279 -- that it might be more consistent to apply these only when
4280 -- expansion is active (in Exp_Ch6.Expand_Actuals), as we do
4281 -- for the outbound predicate tests ??? In any case indicate
4282 -- the function being called, for better warnings if the call
4283 -- leads to an infinite recursion.
4289 -- Apply required constraint checks
4291 -- Gigi looks at the check flag and uses the appropriate types.
4292 -- For now since one flag is used there is an optimization
4293 -- which might not be done in the IN OUT case since Gigi does
4294 -- not do any analysis. More thought required about this ???
4296 -- In fact is this comment obsolete??? doesn't the expander now
4297 -- generate all these tests anyway???
4310 then
4313 -- For view conversions of a discriminated object, apply
4314 -- check to object itself, the conversion alreay has the
4315 -- proper type.
4319 then
4326 then
4332 then
4335 else
4339 -- Ada 2005 (AI-231): Note that the controlling parameter case
4340 -- already existed in Ada 95, which is partially checked
4341 -- elsewhere (see Checks), and we don't want the warning
4342 -- message to differ.
4347 then
4349 Apply_Compile_Time_Constraint_Error
4355 Apply_Compile_Time_Constraint_Error
4364 -- Checks for OUT parameters and IN OUT parameters
4368 -- If there is a type conversion, make sure the return value
4369 -- meets the constraints of the variable before the conversion.
4373 Apply_Scalar_Range_Check
4376 -- In addition, the returned value of the parameter must
4377 -- satisfy the bounds of the object type (see comment
4378 -- below).
4382 else
4383 Apply_Range_Check
4387 -- If no conversion, apply scalar range checks and length check
4388 -- based on the subtype of the actual (NOT that of the formal).
4389 -- This indicates that the check takes place on return from the
4390 -- call. During expansion the required constraint checks are
4391 -- inserted. In GNATprove mode, in the absence of expansion,
4392 -- the flag indicates that the returned value is valid.
4394 else
4400 then
4402 else
4407 -- Note: we do not apply the predicate checks for the case of
4408 -- OUT and IN OUT parameters. They are instead applied in the
4409 -- Expand_Actuals routine in Exp_Ch6.
4412 -- An actual associated with an access parameter is implicitly
4413 -- converted to the anonymous access type of the formal and must
4414 -- satisfy the legality checks for access conversions.
4418 Error_Msg_N
4422 -- If the actual is an access selected component of a variable,
4423 -- the call may modify its designated object. It is reasonable
4424 -- to treat this as a potential modification of the enclosing
4425 -- record, to prevent spurious warnings that it should be
4426 -- declared as a constant, because intuitively programmers
4427 -- regard the designated subcomponent as part of the record.
4432 then
4437 -- Check bad case of atomic/volatile argument (RM C.6(12))
4441 then
4444 then
4445 Error_Msg_NE
4451 then
4452 Error_Msg_NE
4458 -- Check that subprograms don't have improper controlling
4459 -- arguments (RM 3.9.2 (9)).
4461 -- A primitive operation may have an access parameter of an
4462 -- incomplete tagged type, but a dispatching call is illegal
4463 -- if the type is still incomplete.
4469 declare
4471 begin
4475 then
4476 Error_Msg_NE
4487 -- Apply legality rule 3.9.2 (9/1)
4492 and then not In_Instance
4493 then
4498 Error_Msg_NE
4502 -- Apply the checks described in 3.10.2(27): if the context is a
4503 -- specific access-to-object, the actual cannot be class-wide.
4504 -- Use base type to exclude access_to_subprogram cases.
4511 and then
4516 -- Disable these checks for call to imported C++ subprograms
4518 and then not
4522 then
4523 Error_Msg_N
4528 Error_Msg_NE
4533 Check_Aliased_Parameter;
4537 -- If it is a named association, treat the selector_name as a
4538 -- proper identifier, and mark the corresponding entity.
4542 -- Ignore reference in SPARK mode, as it refers to an entity not
4543 -- in scope at the point of reference, so the reference should
4544 -- be ignored for computing effects of subprograms.
4546 and then not GNATprove_Mode
4547 then
4548 -- If subprogram is overridden, use name of formal that
4549 -- is being called.
4555 else
4569 -- The following checks are only relevant when SPARK_Mode is on as
4570 -- they are not standard Ada legality rule. Internally generated
4571 -- temporaries are ignored.
4575 -- An effectively volatile object may act as an actual when the
4576 -- corresponding formal is of a non-scalar effectively volatile
4577 -- type (SPARK RM 7.1.3(11)).
4581 then
4584 -- An effectively volatile object may act as an actual in a
4585 -- call to an instance of Unchecked_Conversion.
4586 -- (SPARK RM 7.1.3(11)).
4591 -- The actual denotes an object
4594 Error_Msg_N
4598 -- Otherwise the actual denotes an expression. Inspect the
4599 -- expression and flag each effectively volatile object with
4600 -- enabled property Async_Writers or Effective_Reads as illegal
4601 -- because it apprears within an interfering context. Note that
4602 -- this is usually done in Resolve_Entity_Name, but when the
4603 -- effectively volatile object appears as an actual in a call,
4604 -- the call must be resolved first.
4606 else
4610 -- Detect an external variable with an enabled property that
4611 -- does not match the mode of the corresponding formal in a
4612 -- procedure call. Functions are not considered because they
4613 -- cannot have effectively volatile formal parameters in the
4614 -- first place.
4621 then
4634 -- A formal parameter of a specific tagged type whose related
4635 -- subprogram is subject to pragma Extensions_Visible with value
4636 -- "False" cannot act as an actual in a subprogram with value
4637 -- "True" (SPARK RM 6.1.7(3)).
4641 Extensions_Visible_True
4642 then
4643 Error_Msg_N
4646 Error_Msg_NE
4650 -- The actual parameter of a Ghost subprogram whose formal is of
4651 -- mode IN OUT or OUT must be a Ghost variable (SPARK RM 6.9(12)).
4659 then
4660 Error_Msg_NE
4666 else
4673 -- Case where actual is not present
4675 else
4676 Insert_Default;
4687 -----------------------
4688 -- Resolve_Allocator --
4689 -----------------------
4701 procedure Check_Allocator_Discrim_Accessibility
4704 -- Check that accessibility level associated with an access discriminant
4705 -- initialized in an allocator by the expression Disc_Exp is not deeper
4706 -- than the level of the allocator type Alloc_Typ. An error message is
4707 -- issued if this condition is violated. Specialized checks are done for
4708 -- the cases of a constraint expression which is an access attribute or
4709 -- an access discriminant.
4712 -- If the allocator is an actual in a call, it is allowed to be class-
4713 -- wide when the context is not because it is a controlling actual.
4715 -------------------------------------------
4716 -- Check_Allocator_Discrim_Accessibility --
4717 -------------------------------------------
4719 procedure Check_Allocator_Discrim_Accessibility
4722 is
4723 begin
4726 then
4727 Error_Msg_N
4730 -- When the expression is an Access attribute the level of the prefix
4731 -- object must not be deeper than that of the allocator's type.
4735 Attribute_Access
4738 then
4739 Error_Msg_N
4741 Disc_Exp);
4743 -- When the expression is an access discriminant the check is against
4744 -- the level of the prefix object.
4750 then
4751 Error_Msg_N
4753 Disc_Exp);
4755 -- All other cases are legal
4757 else
4762 ----------------------------
4763 -- In_Dispatching_Context --
4764 ----------------------------
4769 begin
4775 -- Start of processing for Resolve_Allocator
4777 begin
4778 -- Replace general access with specific type
4788 -- For qualified expression, resolve the expression using the given
4789 -- subtype (nothing to do for type mark, subtype indication)
4794 and then not In_Dispatching_Context
4795 then
4796 Error_Msg_N
4804 -- Allocators generated by the build-in-place expansion mechanism
4805 -- are explicitly marked as coming from source but do not need to be
4806 -- checked for limited initialization. To exclude this case, ensure
4807 -- that the parent of the allocator is a source node.
4812 and then not In_Instance_Body
4813 then
4816 Error_Msg_N
4819 else
4820 Error_Msg_N
4828 -- A qualified expression requires an exact match of the type. Class-
4829 -- wide matching is not allowed.
4834 then
4838 -- Calls to build-in-place functions are not currently supported in
4839 -- allocators for access types associated with a simple storage pool.
4840 -- Supporting such allocators may require passing additional implicit
4841 -- parameters to build-in-place functions (or a significant revision
4842 -- of the current b-i-p implementation to unify the handling for
4843 -- multiple kinds of storage pools). ???
4847 then
4848 declare
4851 begin
4853 and then
4854 Present (Get_Rep_Pragma
4856 then
4857 Error_Msg_N
4864 -- A special accessibility check is needed for allocators that
4865 -- constrain access discriminants. The level of the type of the
4866 -- expression used to constrain an access discriminant cannot be
4867 -- deeper than the type of the allocator (in contrast to access
4868 -- parameters, where the level of the actual can be arbitrary).
4870 -- We can't use Valid_Conversion to perform this check because in
4871 -- general the type of the allocator is unrelated to the type of
4872 -- the access discriminant.
4876 then
4883 then
4886 -- Get the first component expression of the aggregate
4896 else
4900 else
4919 else
4924 else
4933 -- For a subtype mark or subtype indication, freeze the subtype
4935 else
4939 Error_Msg_N
4943 -- A special accessibility check is needed for allocators that
4944 -- constrain access discriminants. The level of the type of the
4945 -- expression used to constrain an access discriminant cannot be
4946 -- deeper than the type of the allocator (in contrast to access
4947 -- parameters, where the level of the actual can be arbitrary).
4948 -- We can't use Valid_Conversion to perform this check because
4949 -- in general the type of the allocator is unrelated to the type
4950 -- of the access discriminant.
4955 then
4965 else
4979 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
4980 -- check that the level of the type of the created object is not deeper
4981 -- than the level of the allocator's access type, since extensions can
4982 -- now occur at deeper levels than their ancestor types. This is a
4983 -- static accessibility level check; a run-time check is also needed in
4984 -- the case of an initialized allocator with a class-wide argument (see
4985 -- Expand_Allocator_Expression).
4989 then
4990 declare
4993 begin
4998 else
5004 then
5007 Error_Msg_N
5016 -- Do not apply Ada 2005 accessibility checks on a class-wide
5017 -- allocator if the type given in the allocator is a formal
5018 -- type. A run-time check will be performed in the instance.
5028 -- Check for allocation from an empty storage pool
5033 -- If the context is an unchecked conversion, as may happen within an
5034 -- inlined subprogram, the allocator is being resolved with its own
5035 -- anonymous type. In that case, if the target type has a specific
5036 -- storage pool, it must be inherited explicitly by the allocator type.
5040 then
5041 Set_Associated_Storage_Pool
5049 -- Check that an allocator with task parts isn't for a nested access
5050 -- type when restriction No_Task_Hierarchy applies.
5054 then
5058 -- An illegal allocator may be rewritten as a raise Program_Error
5059 -- statement.
5063 -- An anonymous access discriminant is the definition of a
5064 -- coextension.
5068 N_Discriminant_Specification
5069 then
5070 declare
5074 begin
5077 -- Ada 2012 AI05-0052: If the designated type of the allocator
5078 -- is limited, then the allocator shall not be used to define
5079 -- the value of an access discriminant unless the discriminated
5080 -- type is immutably limited.
5085 then
5086 Error_Msg_N
5092 -- Avoid marking an allocator as a dynamic coextension if it is
5093 -- within a static construct.
5099 -- Cleanup for potential static coextensions
5101 else
5107 -- Report a simple error: if the designated object is a local task,
5108 -- its body has not been seen yet, and its activation will fail an
5109 -- elaboration check.
5116 then
5122 -- Ada 2012 (AI05-0111-3): Detect an attempt to allocate a task or a
5123 -- type with a task component on a subpool. This action must raise
5124 -- Program_Error at runtime.
5130 then
5142 ---------------------------
5143 -- Resolve_Arithmetic_Op --
5144 ---------------------------
5146 -- Used for resolving all arithmetic operators except exponentiation
5157 -- We do the resolution using the base type, because intermediate values
5158 -- in expressions always are of the base type, not a subtype of it.
5161 -- Returns True if N is in a context that expects "any real type"
5164 -- Return True iff given type is Integer or universal real/integer
5167 -- Choose type of integer literal in fixed-point operation to conform
5168 -- to available fixed-point type. T is the type of the other operand,
5169 -- which is needed to determine the expected type of N.
5172 -- Set operand type to T if universal
5174 -------------------------------
5175 -- Expected_Type_Is_Any_Real --
5176 -------------------------------
5179 begin
5180 -- N is the expression after "delta" in a fixed_point_definition;
5181 -- see RM-3.5.9(6):
5184 N_Decimal_Fixed_Point_Definition,
5186 -- N is one of the bounds in a real_range_specification;
5187 -- see RM-3.5.7(5):
5189 N_Real_Range_Specification,
5191 -- N is the expression of a delta_constraint;
5192 -- see RM-J.3(3):
5194 N_Delta_Constraint);
5197 -----------------------------
5198 -- Is_Integer_Or_Universal --
5199 -----------------------------
5206 begin
5212 else
5218 then
5229 ----------------------------
5230 -- Set_Mixed_Mode_Operand --
5231 ----------------------------
5237 begin
5240 -- A universal integer literal is resolved as standard integer
5241 -- except in the case of a fixed-point result, where we leave it
5242 -- as universal (to be handled by Exp_Fixd later on)
5246 else
5254 then
5255 -- A universal real can appear in a fixed-type context. We resolve
5256 -- the literal with that context, even though this might raise an
5257 -- exception prematurely (the other operand may be zero).
5264 then
5265 -- Integer arg in mixed-mode operation. Resolve with universal
5266 -- type, in case preference rule must be applied.
5272 then
5273 -- Not a mixed-mode operation, resolve with context
5279 -- N may itself be a mixed-mode operation, so use context type
5286 then
5287 -- Must be (fixed * fixed) operation, operand must have one
5288 -- compatible interpretation.
5295 then
5296 -- C * F(X) in a fixed context, where C is a real literal or a
5297 -- fixed-point expression. F must have either a fixed type
5298 -- interpretation or an integer interpretation, but not both.
5305 else
5312 else
5320 -- Reanalyze the literal with the fixed type of the context. If
5321 -- context is Universal_Fixed, we are within a conversion, leave
5322 -- the literal as a universal real because there is no usable
5323 -- fixed type, and the target of the conversion plays no role in
5324 -- the resolution.
5326 declare
5330 begin
5333 else
5339 then
5341 else
5349 else
5354 ----------------------
5355 -- Set_Operand_Type --
5356 ----------------------
5359 begin
5362 then
5367 -- Start of processing for Resolve_Arithmetic_Op
5369 begin
5374 then
5378 -- Special-case for mixed-mode universal expressions or fixed point type
5379 -- operation: each argument is resolved separately. The same treatment
5380 -- is required if one of the operands of a fixed point operation is
5381 -- universal real, since in this case we don't do a conversion to a
5382 -- specific fixed-point type (instead the expander handles the case).
5384 -- Set the type of the node to its universal interpretation because
5385 -- legality checks on an exponentiation operand need the context.
5390 then
5401 or else
5404 then
5409 -- If context is a fixed type and one operand is integer, the other
5410 -- is resolved with the type of the context.
5415 then
5422 then
5426 else
5431 -- Check the rule in RM05-4.5.5(19.1/2) disallowing universal_fixed
5432 -- multiplying operators from being used when the expected type is
5433 -- also universal_fixed. Note that B_Typ will be Universal_Fixed in
5434 -- some cases where the expected type is actually Any_Real;
5435 -- Expected_Type_Is_Any_Real takes care of that case.
5439 then
5443 N_Unchecked_Type_Conversion)
5444 then
5451 else
5454 and then not
5456 N_Unchecked_Type_Conversion)
5457 then
5458 Error_Msg_N
5463 -- The expected type is "any real type" in contexts like
5465 -- type T is delta <universal_fixed-expression> ...
5467 -- in which case we need to set the type to Universal_Real
5468 -- so that static expression evaluation will work properly.
5472 else
5482 then
5487 -- If no previous errors, this is only possible if one operand is
5488 -- overloaded and the context is universal. Resolve as such.
5493 else
5495 and then
5497 then
5501 -- If the context is Universal_Fixed and the operands are also
5502 -- universal fixed, this is an error, unless there is only one
5503 -- applicable fixed_point type (usually Duration).
5511 else
5516 else
5521 -- If one of the arguments was resolved to a non-universal type.
5522 -- label the result of the operation itself with the same type.
5523 -- Do the same for the universal argument, if any.
5535 -- In SPARK, a multiplication or division with operands of fixed point
5536 -- types must be qualified or explicitly converted to identify the
5537 -- result type.
5542 and then
5544 then
5545 Check_SPARK_05_Restriction
5549 -- Set overflow and division checking bit
5556 -- Give warning if explicit division by zero
5560 then
5566 or else
5569 then
5570 -- Specialize the warning message according to the operation.
5571 -- When SPARK_Mode is On, force a warning instead of an error
5572 -- in that case, as this likely corresponds to deactivated
5573 -- code. The following warnings are for the case
5578 -- For division, we have two cases, for float division
5579 -- of an unconstrained float type, on a machine where
5580 -- Machine_Overflows is false, we don't get an exception
5581 -- at run-time, but rather an infinity or Nan. The Nan
5582 -- case is pretty obscure, so just warn about infinities.
5586 and then not Machine_Overflows_On_Target
5587 then
5588 Error_Msg_N
5592 -- For all other cases, we get a Constraint_Error
5594 else
5595 Apply_Compile_Time_Constraint_Error
5602 Apply_Compile_Time_Constraint_Error
5608 Apply_Compile_Time_Constraint_Error
5613 -- Division by zero can only happen with division, rem,
5614 -- and mod operations.
5620 -- In GNATprove mode, we enable the division check so that
5621 -- GNATprove will issue a message if it cannot be proved.
5627 -- Otherwise just set the flag to check at run time
5629 else
5634 -- If Restriction No_Implicit_Conditionals is active, then it is
5635 -- violated if either operand can be negative for mod, or for rem
5636 -- if both operands can be negative.
5640 then
5641 declare
5648 -- Set if corresponding operand might be negative
5650 begin
5651 Determine_Range
5655 Determine_Range
5659 -- Check if we will be generating conditionals. There are two
5660 -- cases where that can happen, first for REM, the only case
5661 -- is largest negative integer mod -1, where the division can
5662 -- overflow, but we still have to give the right result. The
5663 -- front end generates a test for this annoying case. Here we
5664 -- just test if both operands can be negative (that's what the
5665 -- expander does, so we match its logic here).
5667 -- The second case is mod where either operand can be negative.
5668 -- In this case, the back end has to generate additional tests.
5671 or else
5673 then
5684 ------------------
5685 -- Resolve_Call --
5686 ------------------
5689 function Same_Or_Aliased_Subprograms
5692 -- Returns True if the subprogram entity S is the same as E or else
5693 -- S is an alias of E.
5695 ---------------------------------
5696 -- Same_Or_Aliased_Subprograms --
5697 ---------------------------------
5699 function Same_Or_Aliased_Subprograms
5702 is
5704 begin
5708 -- Local variables
5722 -- Start of processing for Resolve_Call
5724 begin
5725 -- The context imposes a unique interpretation with type Typ on a
5726 -- procedure or function call. Find the entity of the subprogram that
5727 -- yields the expected type, and propagate the corresponding formal
5728 -- constraints on the actuals. The caller has established that an
5729 -- interpretation exists, and emitted an error if not unique.
5731 -- First deal with the case of a call to an access-to-subprogram,
5732 -- dereference made explicit in Analyze_Call.
5738 else
5739 -- Find the interpretation whose type (a subprogram type) has a
5740 -- return type that is compatible with the context. Analysis of
5741 -- the node has established that one exists.
5760 -- If the prefix is not an entity, then resolve it
5766 -- For an indirect call, we always invalidate checks, since we do not
5767 -- know whether the subprogram is local or global. Yes we could do
5768 -- better here, e.g. by knowing that there are no local subprograms,
5769 -- but it does not seem worth the effort. Similarly, we kill all
5770 -- knowledge of current constant values.
5772 Kill_Current_Values;
5774 -- If this is a procedure call which is really an entry call, do
5775 -- the conversion of the procedure call to an entry call. Protected
5776 -- operations use the same circuitry because the name in the call
5777 -- can be an arbitrary expression with special resolution rules.
5782 then
5786 -- Kill checks and constant values, as above for indirect case
5787 -- Who knows what happens when another task is activated?
5789 Kill_Current_Values;
5792 -- Normal subprogram call with name established in Resolve
5798 -- Otherwise we must have the case of an overloaded call
5800 else
5803 -- Initialize Nam to prevent warning (we know it will be assigned
5804 -- in the loop below, but the compiler does not know that).
5824 then
5825 -- The prefix is a parameterless function call that returns an access
5826 -- to subprogram. If parameters are present in the current call, add
5827 -- add an explicit dereference. We use the base type here because
5828 -- within an instance these may be subtypes.
5830 -- The dereference is added either in Analyze_Call or here. Should
5831 -- be consolidated ???
5840 -- Check that a call to Current_Task does not occur in an entry body
5843 declare
5846 begin
5848 loop
5851 -- Exclude calls that occur within the default of a formal
5852 -- parameter of the entry, since those are evaluated outside
5853 -- of the body.
5860 then
5863 Error_Msg_NE
5877 -- Check that a procedure call does not occur in the context of the
5878 -- entry call statement of a conditional or timed entry call. Note that
5879 -- the case of a call to a subprogram renaming of an entry will also be
5880 -- rejected. The test for N not being an N_Entry_Call_Statement is
5881 -- defensive, covering the possibility that the processing of entry
5882 -- calls might reach this point due to later modifications of the code
5883 -- above.
5888 then
5892 -- Ada 2005 (AI-345): If a procedure_call_statement is used
5893 -- for a procedure_or_entry_call, the procedure_name or
5894 -- procedure_prefix of the procedure_call_statement shall denote
5895 -- an entry renamed by a procedure, or (a view of) a primitive
5896 -- subprogram of a limited interface whose first parameter is
5897 -- a controlling parameter.
5902 then
5903 Error_Msg_N
5908 -- If the SPARK_05 restriction is active, we are not allowed
5909 -- to have a call to a subprogram before we see its completion.
5914 -- Don't flag strange internal calls
5919 -- Only flag calls in extended main source
5924 -- Exclude enumeration literals from this processing
5927 then
5928 Check_SPARK_05_Restriction
5932 -- Check that this is not a call to a protected procedure or entry from
5933 -- within a protected function.
5937 -- Freeze the subprogram name if not in a spec-expression. Note that
5938 -- we freeze procedure calls as well as function calls. Procedure calls
5939 -- are not frozen according to the rules (RM 13.14(14)) because it is
5940 -- impossible to have a procedure call to a non-frozen procedure in
5941 -- pure Ada, but in the code that we generate in the expander, this
5942 -- rule needs extending because we can generate procedure calls that
5943 -- need freezing.
5945 -- In Ada 2012, expression functions may be called within pre/post
5946 -- conditions of subsequent functions or expression functions. Such
5947 -- calls do not freeze when they appear within generated bodies,
5948 -- (including the body of another expression function) which would
5949 -- place the freeze node in the wrong scope. An expression function
5950 -- is frozen in the usual fashion, by the appearance of a real body,
5951 -- or at the end of a declarative part.
5954 and then not In_Spec_Expression
5956 and then
5959 then
5963 -- For a predefined operator, the type of the result is the type imposed
5964 -- by context, except for a predefined operation on universal fixed.
5965 -- Otherwise The type of the call is the type returned by the subprogram
5966 -- being called.
5973 -- If the subprogram returns an array type, and the context requires the
5974 -- component type of that array type, the node is really an indexing of
5975 -- the parameterless call. Resolve as such. A pathological case occurs
5976 -- when the type of the component is an access to the array type. In
5977 -- this case the call is truly ambiguous. If the call is to an intrinsic
5978 -- subprogram, it can't be an indexed component. This check is necessary
5979 -- because if it's Unchecked_Conversion, and we have "type T_Ptr is
5980 -- access T;" and "type T is array (...) of T_Ptr;" (i.e. an array of
5981 -- pointers to the same array), the compiler gets confused and does an
5982 -- infinite recursion.
5985 and then
5988 or else
5991 and then
5994 then
5995 declare
6000 begin
6003 then
6004 Error_Msg_N
6006 else
6009 -- The called entity may be an explicit dereference, in which
6010 -- case there is no entity to set.
6018 or else
6020 and then
6022 then
6025 -- Indexed call to a parameterless function
6027 Index_Node :=
6029 Prefix =>
6032 else
6033 -- An Ada 2005 prefixed call to a primitive operation
6034 -- whose first parameter is the prefix. This prefix was
6035 -- prepended to the parameter list, which is actually a
6036 -- list of indexes. Remove the prefix in order to build
6037 -- the proper indexed component.
6039 Index_Node :=
6041 Prefix =>
6044 Parameter_Associations =>
6045 New_List
6050 -- Preserve the parenthesis count of the node
6054 -- Since we are correcting a node classification error made
6055 -- by the parser, we call Replace rather than Rewrite.
6069 else
6070 -- If the called function is not declared in the main unit and it
6071 -- returns the limited view of type then use the available view (as
6072 -- is done in Try_Object_Operation) to prevent back-end confusion;
6073 -- the call must appear in a context where the nonlimited view is
6074 -- available. If the called function is in the extended main unit
6075 -- then no action is needed, because the back end handles this case.
6079 then
6086 -- In the case where the call is to an overloaded subprogram, Analyze
6087 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
6088 -- such a case Normalize_Actuals needs to be called once more to order
6089 -- the actuals correctly. Otherwise the call will have the ordering
6090 -- given by the last overloaded subprogram whether this is the correct
6091 -- one being called or not.
6098 -- In any case, call is fully resolved now. Reset Overload flag, to
6099 -- prevent subsequent overload resolution if node is analyzed again
6104 -- A Ghost entity must appear in a specific context
6110 -- If we are calling the current subprogram from immediately within its
6111 -- body, then that is the case where we can sometimes detect cases of
6112 -- infinite recursion statically. Do not try this in case restriction
6113 -- No_Recursion is in effect anyway, and do it only for source calls.
6118 -- Check violation of SPARK_05 restriction which does not permit
6119 -- a subprogram body to contain a call to the subprogram directly.
6123 then
6124 Check_SPARK_05_Restriction
6128 -- Issue warning for possible infinite recursion in the absence
6129 -- of the No_Recursion restriction.
6134 then
6135 -- Here we detected and flagged an infinite recursion, so we do
6136 -- not need to test the case below for further warnings. Also we
6137 -- are all done if we now have a raise SE node.
6143 -- If call is to immediately containing subprogram, then check for
6144 -- the case of a possible run-time detectable infinite recursion.
6146 else
6150 -- Although in general case, recursion is not statically
6151 -- checkable, the case of calling an immediately containing
6152 -- subprogram is easy to catch.
6156 -- If the recursive call is to a parameterless subprogram,
6157 -- then even if we can't statically detect infinite
6158 -- recursion, this is pretty suspicious, and we output a
6159 -- warning. Furthermore, we will try later to detect some
6160 -- cases here at run time by expanding checking code (see
6161 -- Detect_Infinite_Recursion in package Exp_Ch6).
6163 -- If the recursive call is within a handler, do not emit a
6164 -- warning, because this is a common idiom: loop until input
6165 -- is correct, catch illegal input in handler and restart.
6171 then
6172 -- For the case of a procedure call. We give the message
6173 -- only if the call is the first statement in a sequence
6174 -- of statements, or if all previous statements are
6175 -- simple assignments. This is simply a heuristic to
6176 -- decrease false positives, without losing too many good
6177 -- warnings. The idea is that these previous statements
6178 -- may affect global variables the procedure depends on.
6179 -- We also exclude raise statements, that may arise from
6180 -- constraint checks and are probably unrelated to the
6181 -- intended control flow.
6185 then
6186 declare
6188 begin
6192 N_Raise_Constraint_Error)
6193 then
6202 -- Do not give warning if we are in a conditional context
6204 declare
6206 begin
6212 then
6217 -- Here warning is to be issued
6233 -- Check obsolescent reference to Ada.Characters.Handling subprogram
6237 -- If subprogram name is a predefined operator, it was given in
6238 -- functional notation. Replace call node with operator node, so
6239 -- that actuals can be resolved appropriately.
6247 then
6253 -- Create a transient scope if the resulting type requires it
6255 -- There are several notable exceptions:
6257 -- a) In init procs, the transient scope overhead is not needed, and is
6258 -- even incorrect when the call is a nested initialization call for a
6259 -- component whose expansion may generate adjust calls. However, if the
6260 -- call is some other procedure call within an initialization procedure
6261 -- (for example a call to Create_Task in the init_proc of the task
6262 -- run-time record) a transient scope must be created around this call.
6264 -- b) Enumeration literal pseudo-calls need no transient scope
6266 -- c) Intrinsic subprograms (Unchecked_Conversion and source info
6267 -- functions) do not use the secondary stack even though the return
6268 -- type may be unconstrained.
6270 -- d) Calls to a build-in-place function, since such functions may
6271 -- allocate their result directly in a target object, and cases where
6272 -- the result does get allocated in the secondary stack are checked for
6273 -- within the specialized Exp_Ch6 procedures for expanding those
6274 -- build-in-place calls.
6276 -- e) Calls to inlinable expression functions do not use the secondary
6277 -- stack (since the call will be replaced by its returned object).
6279 -- f) If the subprogram is marked Inline_Always, then even if it returns
6280 -- an unconstrained type the call does not require use of the secondary
6281 -- stack. However, inlining will only take place if the body to inline
6282 -- is already present. It may not be available if e.g. the subprogram is
6283 -- declared in a child instance.
6285 -- If this is an initialization call for a type whose construction
6286 -- uses the secondary stack, and it is not a nested call to initialize
6287 -- a component, we do need to create a transient scope for it. We
6288 -- check for this by traversing the type in Check_Initialization_Call.
6294 then
6301 then
6304 elsif Expander_Active
6307 and then
6309 or else
6311 then
6314 -- If the call appears within the bounds of a loop, it will
6315 -- be rewritten and reanalyzed, nothing left to do here.
6322 and then not Within_Init_Proc
6323 then
6327 -- A protected function cannot be called within the definition of the
6328 -- enclosing protected type, unless it is part of a pre/postcondition
6329 -- on another protected operation. This may appear in the entry wrapper
6330 -- created for an entry with preconditions.
6335 and then not In_Spec_Expression
6337 then
6338 Error_Msg_NE
6342 -- Propagate interpretation to actuals, and add default expressions
6343 -- where needed.
6348 -- Overloaded literals are rewritten as function calls, for purpose of
6349 -- resolution. After resolution, we can replace the call with the
6350 -- literal itself.
6356 -- Avoid validation, since it is a static function call
6362 -- If the subprogram is not global, then kill all saved values and
6363 -- checks. This is a bit conservative, since in many cases we could do
6364 -- better, but it is not worth the effort. Similarly, we kill constant
6365 -- values. However we do not need to do this for internal entities
6366 -- (unless they are inherited user-defined subprograms), since they
6367 -- are not in the business of molesting local values.
6369 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
6370 -- kill all checks and values for calls to global subprograms. This
6371 -- takes care of the case where an access to a local subprogram is
6372 -- taken, and could be passed directly or indirectly and then called
6373 -- from almost any context.
6375 -- Note: we do not do this step till after resolving the actuals. That
6376 -- way we still take advantage of the current value information while
6377 -- scanning the actuals.
6379 -- We suppress killing values if we are processing the nodes associated
6380 -- with N_Freeze_Entity nodes. Otherwise the declaration of a tagged
6381 -- type kills all the values as part of analyzing the code that
6382 -- initializes the dispatch tables.
6386 or else Suppress_Value_Tracking_On_Call
6391 then
6392 Kill_Current_Values;
6395 -- If we are warning about unread OUT parameters, this is the place to
6396 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
6397 -- after the above call to Kill_Current_Values (since that call clears
6398 -- the Last_Assignment field of all local variables).
6403 then
6404 declare
6408 begin
6418 then
6428 -- If the subprogram is a primitive operation, check whether or not
6429 -- it is a correct dispatching call.
6433 then
6438 and then not In_Instance
6439 then
6443 -- If this is a dispatching call, generate the appropriate reference,
6444 -- for better source navigation in GPS.
6448 then
6451 -- Normal case, not a dispatching call: generate a call reference
6453 else
6461 -- Check for violation of restriction No_Specific_Termination_Handlers
6462 -- and warn on a potentially blocking call to Abort_Task.
6466 or else
6468 then
6475 -- A call to Ada.Real_Time.Timing_Events.Set_Handler to set a relative
6476 -- timing event violates restriction No_Relative_Delay (AI-0211). We
6477 -- need to check the second argument to determine whether it is an
6478 -- absolute or relative timing event.
6483 then
6487 -- Issue an error for a call to an eliminated subprogram. This routine
6488 -- will not perform the check if the call appears within a default
6489 -- expression.
6493 -- In formal mode, the primitive operations of a tagged type or type
6494 -- extension do not include functions that return the tagged type.
6500 then
6504 -- Implement rule in 12.5.1 (23.3/2): In an instance, if the actual is
6505 -- class-wide and the call dispatches on result in a context that does
6506 -- not provide a tag, the call raises Program_Error.
6509 and then In_Instance
6514 then
6515 -- Verify that none of the formals are controlling
6517 declare
6521 begin
6543 -- Check for calling a function with OUT or IN OUT parameter when the
6544 -- calling context (us right now) is not Ada 2012, so does not allow
6545 -- OUT or IN OUT parameters in function calls. Functions declared in
6546 -- a predefined unit are OK, as they may be called indirectly from a
6547 -- user-declared instantiation.
6553 then
6558 -- Check the dimensions of the actuals in the call. For function calls,
6559 -- propagate the dimensions from the returned type to N.
6563 -- All done, evaluate call and deal with elaboration issues
6568 -- In GNATprove mode, expansion is disabled, but we want to inline some
6569 -- subprograms to facilitate formal verification. Indirect calls through
6570 -- a subprogram type or within a generic cannot be inlined. Inlining is
6571 -- performed only for calls subject to SPARK_Mode on.
6573 if GNATprove_Mode
6576 and then not Inside_A_Generic
6577 then
6584 -- Nothing to do if the subprogram is not eligible for inlining in
6585 -- GNATprove mode.
6589 then
6592 -- Calls cannot be inlined inside assertions, as GNATprove treats
6593 -- assertions as logic expressions.
6596 Cannot_Inline
6599 -- Calls cannot be inlined inside default expressions
6602 Cannot_Inline
6605 -- Inlining should not be performed during pre-analysis
6609 -- With the one-pass inlining technique, a call cannot be
6610 -- inlined if the corresponding body has not been seen yet.
6613 Cannot_Inline
6616 -- Nothing to do if there is no body to inline, indicating that
6617 -- the subprogram is not suitable for inlining in GNATprove
6618 -- mode.
6623 -- Do not inline calls inside expression functions, as this
6624 -- would prevent interpreting them as logical formulas in
6625 -- GNATprove.
6628 and then
6630 then
6631 Cannot_Inline
6635 -- Calls cannot be inlined inside potentially unevaluated
6636 -- expressions, as this would create complex actions inside
6637 -- expressions, that are not handled by GNATprove.
6640 Cannot_Inline
6644 -- Do not inline calls which would possibly lead to missing a
6645 -- type conversion check on an input parameter.
6648 Cannot_Inline
6652 -- Otherwise, inline the call
6654 else
6664 -----------------------------
6665 -- Resolve_Case_Expression --
6666 -----------------------------
6674 begin
6681 -- When the expression is of a scalar subtype different from the
6682 -- result subtype, then insert a conversion to ensure the generation
6683 -- of a constraint check.
6693 -- Apply RM 4.5.7 (17/3): whether the expression is statically or
6694 -- dynamically tagged must be known statically.
6702 Error_Msg_N
6715 -------------------------------
6716 -- Resolve_Character_Literal --
6717 -------------------------------
6723 begin
6724 -- Verify that the character does belong to the type of the context
6729 -- Wide_Wide_Character literals must always be defined, since the set
6730 -- of wide wide character literals is complete, i.e. if a character
6731 -- literal is accepted by the parser, then it is OK for wide wide
6732 -- character (out of range character literals are rejected).
6737 -- Always accept character literal for type Any_Character, which
6738 -- occurs in error situations and in comparisons of literals, both
6739 -- of which should accept all literals.
6744 -- For Standard.Character or a type derived from it, check that the
6745 -- literal is in range.
6752 -- For Standard.Wide_Character or a type derived from it, check that the
6753 -- literal is in range.
6760 -- For Standard.Wide_Wide_Character or a type derived from it, we
6761 -- know the literal is in range, since the parser checked.
6766 -- If the entity is already set, this has already been resolved in a
6767 -- generic context, or comes from expansion. Nothing else to do.
6772 -- Otherwise we have a user defined character type, and we can use the
6773 -- standard visibility mechanisms to locate the referenced entity.
6775 else
6788 -- If we fall through, then the literal does not match any of the
6789 -- entries of the enumeration type. This isn't just a constraint error
6790 -- situation, it is an illegality (see RM 4.2).
6792 Error_Msg_NE
6796 ---------------------------
6797 -- Resolve_Comparison_Op --
6798 ---------------------------
6800 -- Context requires a boolean type, and plays no role in resolution.
6801 -- Processing identical to that for equality operators. The result type is
6802 -- the base type, which matters when pathological subtypes of booleans with
6803 -- limited ranges are used.
6810 begin
6811 -- If this is an intrinsic operation which is not predefined, use the
6812 -- types of its declared arguments to resolve the possibly overloaded
6813 -- operands. Otherwise the operands are unambiguous and specify the
6814 -- expected type.
6819 else
6830 -- Skip remaining processing if already set to Any_Type
6836 -- Deal with other error cases
6840 T = Any_Character
6841 then
6844 else
6852 -- Resolve the operands if types OK
6861 -- In SPARK, ordering operators <, <=, >, >= are not defined for Boolean
6862 -- types or array types except String.
6865 Check_SPARK_05_Restriction
6870 then
6871 Check_SPARK_05_Restriction
6875 -- Check comparison on unordered enumeration
6879 Error_Msg_NE
6884 -- Evaluate the relation (note we do this after the above check since
6885 -- this Eval call may change N to True/False.
6891 -----------------------------------------
6892 -- Resolve_Discrete_Subtype_Indication --
6893 -----------------------------------------
6895 procedure Resolve_Discrete_Subtype_Indication
6898 is
6902 begin
6910 else
6920 Error_Msg_NE
6923 -- Rewrite the constraint as a range of Typ
6924 -- to allow compilation to proceed further.
6936 else
6940 -- Additionally, we must check that the bounds are compatible
6941 -- with the given subtype, which might be different from the
6942 -- type of the context.
6946 -- ??? If the above check statically detects a Constraint_Error
6947 -- it replaces the offending bound(s) of the range R with a
6948 -- Constraint_Error node. When the itype which uses these bounds
6949 -- is frozen the resulting call to Duplicate_Subexpr generates
6950 -- a new temporary for the bounds.
6952 -- Unfortunately there are other itypes that are also made depend
6953 -- on these bounds, so when Duplicate_Subexpr is called they get
6954 -- a forward reference to the newly created temporaries and Gigi
6955 -- aborts on such forward references. This is probably sign of a
6956 -- more fundamental problem somewhere else in either the order of
6957 -- itype freezing or the way certain itypes are constructed.
6959 -- To get around this problem we call Remove_Side_Effects right
6960 -- away if either bounds of R are a Constraint_Error.
6962 declare
6966 begin
6982 -------------------------
6983 -- Resolve_Entity_Name --
6984 -------------------------
6986 -- Used to resolve identifiers and expanded names
6989 function Is_Assignment_Or_Object_Expression
6992 -- Determine whether node Context denotes an assignment statement or an
6993 -- object declaration whose expression is node Expr.
6995 ----------------------------------------
6996 -- Is_Assignment_Or_Object_Expression --
6997 ----------------------------------------
6999 function Is_Assignment_Or_Object_Expression
7002 is
7003 begin
7005 N_Object_Declaration)
7007 then
7010 -- Check whether a construct that yields a name is the expression of
7011 -- an assignment statement or an object declaration.
7014 N_Explicit_Dereference,
7015 N_Indexed_Component,
7016 N_Selected_Component,
7017 N_Slice)
7019 or else
7021 N_Unchecked_Type_Conversion)
7023 then
7024 return
7025 Is_Assignment_Or_Object_Expression
7029 -- Otherwise the context is not an assignment statement or an object
7030 -- declaration.
7032 else
7037 -- Local variables
7042 -- Start of processing for Resolve_Entity_Name
7044 begin
7045 -- If garbage from errors, set to Any_Type and return
7052 -- Replace named numbers by corresponding literals. Note that this is
7053 -- the one case where Resolve_Entity_Name must reset the Etype, since
7054 -- it is currently marked as universal.
7064 -- For enumeration literals, we need to make sure that a proper style
7065 -- check is done, since such literals are overloaded, and thus we did
7066 -- not do a style check during the first phase of analysis.
7072 -- Case of (sub)type name appearing in a context where an expression
7073 -- is expected. This is legal if occurrence is a current instance.
7074 -- See RM 8.6 (17/3).
7080 -- Any other use is an error
7082 else
7083 Error_Msg_N
7087 -- Check discriminant use if entity is discriminant in current scope,
7088 -- i.e. discriminant of record or concurrent type currently being
7089 -- analyzed. Uses in corresponding body are unrestricted.
7094 then
7097 -- A parameterless generic function cannot appear in a context that
7098 -- requires resolution.
7103 -- In Ada 83 an OUT parameter cannot be read
7108 or else Is_Assignment_Or_Object_Expression
7111 then
7116 -- In all other cases, just do the possible static evaluation
7118 else
7119 -- A deferred constant that appears in an expression must have a
7120 -- completion, unless it has been removed by in-place expansion of
7121 -- an aggregate. A constant that is a renaming does not need
7122 -- initialization.
7128 and then not In_Spec_Expression
7131 then
7135 then
7137 else
7138 Error_Msg_N
7148 -- When the entity appears in a parameter association, retrieve the
7149 -- related subprogram call.
7157 -- The following checks are only relevant when SPARK_Mode is on as
7158 -- they are not standard Ada legality rules.
7162 -- An effectively volatile object subject to enabled properties
7163 -- Async_Writers or Effective_Reads must appear in non-interfering
7164 -- context (SPARK RM 7.1.3(12)).
7171 then
7172 SPARK_Msg_N
7177 -- Check for possible elaboration issues with respect to reads of
7178 -- variables. The act of renaming the variable is not considered a
7179 -- read as it simply establishes an alias.
7182 and then Dynamic_Elaboration_Checks
7184 then
7188 -- The variable may eventually become a constituent of a single
7189 -- protected/task type. Record the reference now and verify its
7190 -- legality when analyzing the contract of the variable
7191 -- (SPARK RM 9.3).
7198 -- A Ghost entity must appear in a specific context
7206 -------------------
7207 -- Resolve_Entry --
7208 -------------------
7220 -- If the bounds of the entry family being called depend on task
7221 -- discriminants, build a new index subtype where a discriminant is
7222 -- replaced with the value of the discriminant of the target task.
7223 -- The target task is the prefix of the entry name in the call.
7225 -----------------------
7226 -- Actual_Index_Type --
7227 -----------------------
7237 -- If the bound is given by a discriminant, replace with a reference
7238 -- to the discriminant of the same name in the target task. If the
7239 -- entry name is the target of a requeue statement and the entry is
7240 -- in the current protected object, the bound to be used is the
7241 -- discriminal of the object (see Apply_Range_Checks for details of
7242 -- the transformation).
7244 -----------------------------
7245 -- Actual_Discriminant_Ref --
7246 -----------------------------
7252 begin
7257 then
7263 then
7264 -- Note: here Bound denotes a discriminant of the corresponding
7265 -- record type tskV, whose discriminal is a formal of the
7266 -- init-proc tskVIP. What we want is the body discriminal,
7267 -- which is associated to the discriminant of the original
7268 -- concurrent type tsk.
7270 return New_Occurrence_Of
7273 else
7274 Ref :=
7284 -- Start of processing for Actual_Index_Type
7286 begin
7289 then
7292 else
7306 -- Start of processing for Resolve_Entry
7308 begin
7309 -- Find name of entry being called, and resolve prefix of name with its
7310 -- own type. The prefix can be overloaded, and the name and signature of
7311 -- the entry must be taken into account.
7315 -- Case of dealing with entry family within the current tasks
7319 else
7325 -- Entry call to an entry (or entry family) in the current task. This
7326 -- is legal even though the task will deadlock. Rewrite as call to
7327 -- current task.
7329 -- This can also be a call to an entry in an enclosing task. If this
7330 -- is a single task, we have to retrieve its name, because the scope
7331 -- of the entry is the task type, not the object. If the enclosing
7332 -- task is a task type, the identity of the task is given by its own
7333 -- self variable.
7335 -- Finally this can be a requeue on an entry of the same task or
7336 -- protected object.
7343 then
7344 -- S is an enclosing task or protected object. The concurrent
7345 -- declaration has been converted into a type declaration, and
7346 -- the object itself has an object declaration that follows
7347 -- the type in the same declarative part.
7359 -- Call to current task. Will be transformed into call to Self
7366 New_N :=
7369 Selector_Name =>
7376 then
7377 -- Use the entry name (which must be unique at this point) to find
7378 -- the prefix that returns the corresponding task/protected type.
7380 declare
7386 begin
7408 -- Up to this point the expression could have been the actual in a
7409 -- simple entry call, and be given by a named association.
7413 else
7419 ------------------------
7420 -- Resolve_Entry_Call --
7421 ------------------------
7433 begin
7434 -- We kill all checks here, because it does not seem worth the effort to
7435 -- do anything better, an entry call is a big operation.
7437 Kill_All_Checks;
7439 -- Processing of the name is similar for entry calls and protected
7440 -- operation calls. Once the entity is determined, we can complete
7441 -- the resolution of the actuals.
7443 -- The selector may be overloaded, in the case of a protected object
7444 -- with overloaded functions. The type of the context is used for
7445 -- resolution.
7450 then
7451 declare
7455 begin
7474 -- Simple entry call
7482 -- Call to member of entry family
7489 -- We cannot in general check the maximum depth of protected entry calls
7490 -- at compile time. But we can tell that any protected entry call at all
7491 -- violates a specified nesting depth of zero.
7497 -- Use context type to disambiguate a protected function that can be
7498 -- called without actuals and that returns an array type, and where the
7499 -- argument list may be an indexing of the returned value.
7504 and then
7510 and then
7511 Covers
7514 then
7515 declare
7518 begin
7519 Index_Node :=
7521 Prefix =>
7525 -- Since we are correcting a node classification error made by the
7526 -- parser, we call Replace rather than Rewrite.
7539 then
7541 -- Note the entity being called before rewriting the call, so that
7542 -- it appears used at this point.
7546 -- Rewrite as call to the precondition wrapper, adding the task
7547 -- object to the list of actuals. If the call is to a member of an
7548 -- entry family, include the index as well.
7550 declare
7554 begin
7563 New_Call :=
7565 Name =>
7570 -- Preanalyze and resolve new call. Current procedure is called
7571 -- from Resolve_Call, after which expansion will take place.
7578 -- The operation name may have been overloaded. Order the actuals
7579 -- according to the formals of the resolved entity, and set the return
7580 -- type to that of the operation.
7587 -- Reset the Is_Overloaded flag, since resolution is now completed
7589 -- Simple entry call
7594 -- Call to a member of an entry family
7604 -- Create a call reference to the entry
7612 -- Verify that a procedure call cannot masquerade as an entry
7613 -- call where an entry call is expected.
7618 then
7623 then
7628 then
7633 -- After resolution, entry calls and protected procedure calls are
7634 -- changed into entry calls, for expansion. The structure of the node
7635 -- does not change, so it can safely be done in place. Protected
7636 -- function calls must keep their structure because they are
7637 -- subexpressions.
7641 -- A protected operation that is not a function may modify the
7642 -- corresponding object, and cannot apply to a constant. If this
7643 -- is an internal call, the prefix is the type itself.
7649 then
7650 Error_Msg_N
7652 Entry_Name);
7666 -- Protected functions can return on the secondary stack, in which
7667 -- case we must trigger the transient scope mechanism.
7669 elsif Expander_Active
7671 then
7676 -------------------------
7677 -- Resolve_Equality_Op --
7678 -------------------------
7680 -- Both arguments must have the same type, and the boolean context does
7681 -- not participate in the resolution. The first pass verifies that the
7682 -- interpretation is not ambiguous, and the type of the left argument is
7683 -- correctly set, or is Any_Type in case of ambiguity. If both arguments
7684 -- are strings or aggregates, allocators, or Null, they are ambiguous even
7685 -- though they carry a single (universal) type. Diagnose this case here.
7693 -- The resolution rule for if expressions requires that each such must
7694 -- have a unique type. This means that if several dependent expressions
7695 -- are of a non-null anonymous access type, and the context does not
7696 -- impose an expected type (as can be the case in an equality operation)
7697 -- the expression must be rejected.
7700 -- Attempt to explain the nature of a redundant comparison with True. If
7701 -- the expression N is too complex, this routine issues a general error
7702 -- message.
7705 -- In the case of allocators and access attributes, the context must
7706 -- provide an indication of the specific access type to be used. If
7707 -- one operand is of such a "generic" access type, check whether there
7708 -- is a specific visible access type that has the same designated type.
7709 -- This is semantically dubious, and of no interest to any real code,
7710 -- but c48008a makes it all worthwhile.
7712 -------------------------
7713 -- Check_If_Expression --
7714 -------------------------
7720 begin
7727 then
7733 ------------------------
7734 -- Explain_Redundancy --
7735 ------------------------
7742 begin
7745 -- Strip the operand down to an entity
7747 loop
7750 else
7755 -- The construct denotes an entity
7760 -- Do not generate an error message when the comparison is done
7761 -- against the enumeration literal Standard.True.
7765 -- Build a customized error message
7792 -- The construct is too complex to disect, issue a general message
7794 else
7799 -----------------------------
7800 -- Find_Unique_Access_Type --
7801 -----------------------------
7808 begin
7810 E_Access_Attribute_Type)
7811 then
7815 E_Access_Attribute_Type)
7816 then
7818 else
7830 then
7843 -- Start of processing for Resolve_Equality_Op
7845 begin
7856 T = Any_Character
7857 then
7860 else
7869 then
7878 -- If expressions must have a single type, and if the context does
7879 -- not impose one the dependent expressions cannot be anonymous
7880 -- access types.
7882 -- Why no similar processing for case expressions???
7886 E_Anonymous_Access_Subprogram_Type)
7888 E_Anonymous_Access_Subprogram_Type)
7889 then
7897 -- In SPARK, equality operators = and /= for array types other than
7898 -- String are only defined when, for each index position, the
7899 -- operands have equal static bounds.
7903 -- Protect call to Matching_Static_Array_Bounds to avoid costly
7904 -- operation if not needed.
7912 then
7913 Check_SPARK_05_Restriction
7918 -- If the unique type is a class-wide type then it will be expanded
7919 -- into a dispatching call to the predefined primitive. Therefore we
7920 -- check here for potential violation of such restriction.
7926 if Warn_On_Redundant_Constructs
7931 then
7932 Error_Msg_N -- CODEFIX
7942 -- If this is an inequality, it may be the implicit inequality
7943 -- created for a user-defined operation, in which case the corres-
7944 -- ponding equality operation is not intrinsic, and the operation
7945 -- cannot be constant-folded. Else fold.
7950 or else Is_Intrinsic_Subprogram
7952 then
7958 then
7962 -- Ada 2005: If one operand is an anonymous access type, convert the
7963 -- other operand to it, to ensure that the underlying types match in
7964 -- the back-end. Same for access_to_subprogram, and the conversion
7965 -- verifies that the types are subtype conformant.
7967 -- We apply the same conversion in the case one of the operands is a
7968 -- private subtype of the type of the other.
7970 -- Why the Expander_Active test here ???
7972 if Expander_Active
7973 and then
7975 E_Anonymous_Access_Subprogram_Type)
7977 then
7997 ----------------------------------
7998 -- Resolve_Explicit_Dereference --
7999 ----------------------------------
8007 -- The candidate prefix type, if overloaded
8012 begin
8016 -- A useful optimization: check whether the dereference denotes an
8017 -- element of a container, and if so rewrite it as a call to the
8018 -- corresponding Element function.
8020 -- Disabled for now, on advice of ARG. A more restricted form of the
8021 -- predicate might be acceptable ???
8023 -- if Is_Container_Element (N) then
8024 -- return;
8025 -- end if;
8029 -- Use the context type to select the prefix that has the correct
8030 -- designated type. Keep the first match, which will be the inner-
8031 -- most.
8038 then
8043 -- Remove access types that do not match, but preserve access
8044 -- to subprogram interpretations, in case a further dereference
8045 -- is needed (see below).
8058 else
8059 -- If no interpretation covers the designated type of the prefix,
8060 -- this is the pathological case where not all implementations of
8061 -- the prefix allow the interpretation of the node as a call. Now
8062 -- that the expected type is known, Remove other interpretations
8063 -- from prefix, rewrite it as a call, and resolve again, so that
8064 -- the proper call node is generated.
8075 New_N :=
8077 Name =>
8088 -- If not overloaded, resolve P with its own type
8090 else
8094 -- If the prefix might be null, add an access check
8098 then
8102 -- If the designated type is a packed unconstrained array type, and the
8103 -- explicit dereference is not in the context of an attribute reference,
8104 -- then we must compute and set the actual subtype, since it is needed
8105 -- by Gigi. The reason we exclude the attribute case is that this is
8106 -- handled fine by Gigi, and in fact we use such attributes to build the
8107 -- actual subtype. We also exclude generated code (which builds actual
8108 -- subtypes directly if they are needed).
8115 then
8121 -- Note: No Eval processing is required for an explicit dereference,
8122 -- because such a name can never be static.
8126 -------------------------------------
8127 -- Resolve_Expression_With_Actions --
8128 -------------------------------------
8131 begin
8134 -- If N has no actions, and its expression has been constant folded,
8135 -- then rewrite N as just its expression. Note, we can't do this in
8136 -- the general case of Is_Empty_List (Actions (N)) as this would cause
8137 -- Expression (N) to be expanded again.
8141 then
8146 ----------------------------------
8147 -- Resolve_Generalized_Indexing --
8148 ----------------------------------
8156 begin
8157 -- In ASIS mode, propagate the information about the indexes back to
8158 -- to the original indexing node. The generalized indexing is either
8159 -- a function call, or a dereference of one. The actuals include the
8160 -- prefix of the original node, which is the container expression.
8169 loop
8178 -- If expression is to be reanalyzed, reset Generalized_Indexing
8179 -- to recreate call node, as is the case when the expression is
8180 -- part of an expression function.
8189 else
8195 ---------------------------
8196 -- Resolve_If_Expression --
8197 ---------------------------
8206 begin
8211 -- When the "then" expression is of a scalar subtype different from the
8212 -- result subtype, then insert a conversion to ensure the generation of
8213 -- a constraint check. The same is done for the else part below, again
8214 -- comparing subtypes rather than base types.
8218 then
8223 -- If ELSE expression present, just resolve using the determined type
8224 -- If type is universal, resolve to any member of the class.
8233 else
8243 -- Apply RM 4.5.7 (17/3): whether the expression is statically or
8244 -- dynamically tagged must be known statically.
8249 then
8255 -- If no ELSE expression is present, root type must be Standard.Boolean
8256 -- and we provide a Standard.True result converted to the appropriate
8257 -- Boolean type (in case it is a derived boolean type).
8260 Else_Expr :=
8265 else
8274 -------------------------------
8275 -- Resolve_Indexed_Component --
8276 -------------------------------
8284 begin
8292 -- Use the context type to select the prefix that yields the correct
8293 -- component type.
8295 declare
8302 begin
8309 and then
8310 Covers
8313 then
8322 else
8328 else
8339 else
8346 -- If prefix is access type, dereference to get real array type.
8347 -- Note: we do not apply an access check because the expander always
8348 -- introduces an explicit dereference, and the check will happen there.
8354 -- If name was overloaded, set component type correctly now
8355 -- If a misplaced call to an entry family (which has no index types)
8356 -- return. Error will be diagnosed from calling context.
8360 else
8367 -- The prefix may have resolved to a string literal, in which case its
8368 -- etype has a special representation. This is only possible currently
8369 -- if the prefix is a static concatenation, written in functional
8370 -- notation.
8375 else
8382 else
8393 -- Do not generate the warning on suspicious index if we are analyzing
8394 -- package Ada.Tags; otherwise we will report the warning with the
8395 -- Prims_Ptr field of the dispatch table.
8398 or else not
8400 Ada_Tags)
8401 then
8406 -- If the array type is atomic, and the component is not atomic, then
8407 -- this is worth a warning, since we have a situation where the access
8408 -- to the component may cause extra read/writes of the atomic array
8409 -- object, or partial word accesses, which could be unexpected.
8415 and then Has_Atomic_Components
8418 then
8419 Error_Msg_N
8421 Error_Msg_N
8426 -----------------------------
8427 -- Resolve_Integer_Literal --
8428 -----------------------------
8431 begin
8436 --------------------------------
8437 -- Resolve_Intrinsic_Operator --
8438 --------------------------------
8447 -- If the operand is a literal, it cannot be the expression in a
8448 -- conversion. Use a qualified expression instead.
8450 ---------------------
8451 -- Convert_Operand --
8452 ---------------------
8458 begin
8460 Res :=
8466 else
8473 -- Start of processing for Resolve_Intrinsic_Operator
8475 begin
8476 -- We must preserve the original entity in a generic setting, so that
8477 -- the legality of the operation can be verified in an instance.
8492 -- If the result or operand types are private, rewrite with unchecked
8493 -- conversions on the operands and the result, to expose the proper
8494 -- underlying numeric type.
8499 then
8504 else
8525 then
8526 -- Add explicit conversion where needed, and save interpretations in
8527 -- case operands are overloaded.
8534 else
8540 else
8550 else
8555 --------------------------------------
8556 -- Resolve_Intrinsic_Unary_Operator --
8557 --------------------------------------
8559 procedure Resolve_Intrinsic_Unary_Operator
8562 is
8567 begin
8586 else
8591 ------------------------
8592 -- Resolve_Logical_Op --
8593 ------------------------
8598 begin
8601 -- Predefined operations on scalar types yield the base type. On the
8602 -- other hand, logical operations on arrays yield the type of the
8603 -- arguments (and the context).
8607 else
8611 -- The following test is required because the operands of the operation
8612 -- may be literals, in which case the resulting type appears to be
8613 -- compatible with a signed integer type, when in fact it is compatible
8614 -- only with modular types. If the context itself is universal, the
8615 -- operation is illegal.
8623 Error_Msg_N
8631 then
8635 -- Replace AND by AND THEN, or OR by OR ELSE, if Short_Circuit_And_Or
8636 -- is active and the result type is standard Boolean (do not mess with
8637 -- ops that return a nonstandard Boolean type, because something strange
8638 -- is going on).
8640 -- Note: you might expect this replacement to be done during expansion,
8641 -- but that doesn't work, because when the pragma Short_Circuit_And_Or
8642 -- is used, no part of the right operand of an "and" or "or" operator
8643 -- should be executed if the left operand would short-circuit the
8644 -- evaluation of the corresponding "and then" or "or else". If we left
8645 -- the replacement to expansion time, then run-time checks associated
8646 -- with such operands would be evaluated unconditionally, due to being
8647 -- before the condition prior to the rewriting as short-circuit forms
8648 -- during expansion.
8650 if Short_Circuit_And_Or
8653 then
8654 -- Mark the corresponding putative SCO operator as truly a logical
8655 -- (and short-circuit) operator.
8668 -- Case of OR changed to OR ELSE
8670 else
8678 -- Return now, since analysis of the rewritten ops will take care of
8679 -- other reference bookkeeping and expression folding.
8694 -- In SPARK, logical operations AND, OR and XOR for arrays are defined
8695 -- only when both operands have same static lower and higher bounds. Of
8696 -- course the types have to match, so only check if operands are
8697 -- compatible and the node itself has no errors.
8701 then
8702 declare
8706 begin
8707 -- Protect call to Matching_Static_Array_Bounds to avoid costly
8708 -- operation if not needed.
8715 then
8716 Check_SPARK_05_Restriction
8723 ---------------------------
8724 -- Resolve_Membership_Op --
8725 ---------------------------
8727 -- The context can only be a boolean type, and does not determine the
8728 -- arguments. Arguments should be unambiguous, but the preference rule for
8729 -- universal types applies.
8739 -- Analysis has determined a unique type for the left operand. Use it to
8740 -- resolve the disjuncts.
8742 ----------------------------
8743 -- Resolve_Set_Membership --
8744 ----------------------------
8750 begin
8751 -- If the left operand is overloaded, find type compatible with not
8752 -- overloaded alternative of the right operand.
8761 else
8766 -- Unclear how to resolve expression if all alternatives are also
8767 -- overloaded.
8773 else
8782 -- Alternative is an expression, a range
8783 -- or a subtype mark.
8787 then
8794 -- Check for duplicates for discrete case
8797 declare
8806 begin
8807 -- Loop checking duplicates. This is quadratic, but giant sets
8808 -- are unlikely in this context so it's a reasonable choice.
8815 N_Character_Literal)
8817 then
8835 -- Start of processing for Resolve_Membership_Op
8837 begin
8843 Resolve_Set_Membership;
8847 and then
8849 or else
8852 then
8855 -- Ada 2005 (AI-251): Support the following case:
8857 -- type I is interface;
8858 -- type T is tagged ...
8860 -- function Test (O : I'Class) is
8861 -- begin
8862 -- return O in T'Class.
8863 -- end Test;
8865 -- In this case we have nothing else to do. The membership test will be
8866 -- done at run time.
8873 then
8875 else
8879 -- If mixed-mode operations are present and operands are all literal,
8880 -- the only interpretation involves Duration, which is probably not
8881 -- the intention of the programmer.
8896 then
8902 else
8907 -- Here after resolving membership operation
8914 ------------------
8915 -- Resolve_Null --
8916 ------------------
8921 begin
8922 -- Handle restriction against anonymous null access values This
8923 -- restriction can be turned off using -gnatdj.
8925 -- Ada 2005 (AI-231): Remove restriction
8928 and then not Debug_Flag_J
8931 then
8932 -- In the common case of a call which uses an explicitly null value
8933 -- for an access parameter, give specialized error message.
8936 Error_Msg_N
8939 -- Standard message for all other cases (are there any?)
8941 else
8942 Error_Msg_N
8947 -- Ada 2005 (AI-231): Generate the null-excluding check in case of
8948 -- assignment to a null-excluding object
8953 then
8955 Insert_Action
8960 else
8967 -- In a distributed context, null for a remote access to subprogram may
8968 -- need to be replaced with a special record aggregate. In this case,
8969 -- return after having done the transformation.
8974 then
8978 -- The null literal takes its type from the context
8983 -----------------------
8984 -- Resolve_Op_Concat --
8985 -----------------------
8989 -- We wish to avoid deep recursion, because concatenations are often
8990 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
8991 -- operands nonrecursively until we find something that is not a simple
8992 -- concatenation (A in this case). We resolve that, and then walk back
8993 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
8994 -- to do the rest of the work at each level. The Parent pointers allow
8995 -- us to avoid recursion, and thus avoid running out of memory. See also
8996 -- Sem_Ch4.Analyze_Concatenation, where a similar approach is used.
9001 begin
9002 -- The following code is equivalent to:
9004 -- Resolve_Op_Concat_First (NN, Typ);
9005 -- Resolve_Op_Concat_Arg (N, ...);
9006 -- Resolve_Op_Concat_Rest (N, Typ);
9008 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
9009 -- operand is a concatenation.
9011 -- Walk down left operands
9013 loop
9022 -- Now (given the above example) NN is A&B and Op1 is A
9024 -- First resolve Op1 ...
9028 -- ... then walk NN back up until we reach N (where we started), calling
9029 -- Resolve_Op_Concat_Rest along the way.
9031 loop
9038 Check_SPARK_05_Restriction
9043 ---------------------------
9044 -- Resolve_Op_Concat_Arg --
9045 ---------------------------
9047 procedure Resolve_Op_Concat_Arg
9052 is
9056 begin
9058 if Is_Comp
9062 then
9064 else
9068 -- If both Array & Array and Array & Component are visible, there is a
9069 -- potential ambiguity that must be reported.
9074 then
9078 -- If the operation is user-defined and not overloaded use its
9079 -- profile. The operation may be a renaming, in which case it has
9080 -- been rewritten, and we want the original profile.
9085 then
9087 Etype
9091 -- Otherwise an aggregate may match both the array type and the
9092 -- component type.
9094 else
9099 else
9103 then
9104 declare
9109 begin
9114 -- Special-case the error message when the overloading is
9115 -- caused by a function that yields an array and can be
9116 -- called without parameters.
9121 Error_Msg_NE
9123 Error_Msg_NE
9127 else
9135 or else
9137 then
9138 Error_Msg_N -- CODEFIX
9156 else
9161 else
9165 -- Concatenation is restricted in SPARK: each operand must be either a
9166 -- string literal, the name of a string constant, a static character or
9167 -- string expression, or another concatenation. Arg cannot be a
9168 -- concatenation here as callers of Resolve_Op_Concat_Arg call it
9169 -- separately on each final operand, past concatenation operations.
9173 Check_SPARK_05_Restriction
9181 then
9182 Check_SPARK_05_Restriction
9186 -- Do not issue error on an operand that is neither a character nor a
9187 -- string, as the error is issued in Resolve_Op_Concat.
9189 else
9196 -----------------------------
9197 -- Resolve_Op_Concat_First --
9198 -----------------------------
9205 begin
9206 -- The parser folds an enormous sequence of concatenations of string
9207 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
9208 -- in the right operand. If the expression resolves to a predefined "&"
9209 -- operator, all is well. Otherwise, the parser's folding is wrong, so
9210 -- we give an error. See P_Simple_Expression in Par.Ch4.
9215 then
9230 ----------------------------
9231 -- Resolve_Op_Concat_Rest --
9232 ----------------------------
9238 begin
9247 -- If this is not a static concatenation, but the result is a string
9248 -- type (and not an array of strings) ensure that static string operands
9249 -- have their subtypes properly constructed.
9253 then
9259 ----------------------
9260 -- Resolve_Op_Expon --
9261 ----------------------
9266 begin
9267 -- Catch attempts to do fixed-point exponentiation with universal
9268 -- operands, which is a case where the illegality is not caught during
9269 -- normal operator analysis. This is not done in preanalysis mode
9270 -- since the tree is not fully decorated during preanalysis.
9281 then
9291 then
9298 then
9302 -- We do the resolution using the base type, because intermediate values
9303 -- in expressions are always of the base type, not a subtype of it.
9308 -- For integer types, right argument must be in Natural range
9323 -- Evaluate the exponentiation operator for dimensioned type
9326 else
9330 -- Set overflow checking bit. Much cleverer code needed here eventually
9331 -- and perhaps the Resolve routines should be separated for the various
9332 -- arithmetic operations, since they will need different processing. ???
9341 --------------------
9342 -- Resolve_Op_Not --
9343 --------------------
9349 -- This function determines if the parent node is a boolean operator or
9350 -- operation (comparison op, membership test, or short circuit form) and
9351 -- the not in question is the left operand of this operation. Note that
9352 -- if the not is in parens, then false is returned.
9354 -----------------------
9355 -- Parent_Is_Boolean --
9356 -----------------------
9359 begin
9363 else
9365 when N_And_Then
9366 | N_In
9367 | N_Not_In
9368 | N_Op_And
9369 | N_Op_Eq
9370 | N_Op_Ge
9371 | N_Op_Gt
9372 | N_Op_Le
9373 | N_Op_Lt
9374 | N_Op_Ne
9375 | N_Op_Or
9376 | N_Op_Xor
9377 | N_Or_Else
9378 =>
9387 -- Start of processing for Resolve_Op_Not
9389 begin
9390 -- Predefined operations on scalar types yield the base type. On the
9391 -- other hand, logical operations on arrays yield the type of the
9392 -- arguments (and the context).
9396 else
9400 -- Straightforward case of incorrect arguments
9407 -- Special case of probable missing parens
9411 Error_Msg_N
9414 else
9415 Error_Msg_N
9422 -- OK resolution of NOT
9424 else
9425 -- Warn if non-boolean types involved. This is a case like not a < b
9426 -- where a and b are modular, where we will get (not a) < b and most
9427 -- likely not (a < b) was intended.
9429 if Warn_On_Questionable_Missing_Parens
9431 and then Parent_Is_Boolean
9432 then
9436 -- Warn on double negation if checking redundant constructs
9438 if Warn_On_Redundant_Constructs
9443 then
9447 -- Complete resolution and evaluation of NOT
9457 -----------------------------
9458 -- Resolve_Operator_Symbol --
9459 -----------------------------
9461 -- Nothing to be done, all resolved already
9467 begin
9471 ----------------------------------
9472 -- Resolve_Qualified_Expression --
9473 ----------------------------------
9481 begin
9484 -- Protect call to Matching_Static_Array_Bounds to avoid costly
9485 -- operation if not needed.
9492 then
9493 Check_SPARK_05_Restriction
9497 -- A qualified expression requires an exact match of the type, class-
9498 -- wide matching is not allowed. However, if the qualifying type is
9499 -- specific and the expression has a class-wide type, it may still be
9500 -- okay, since it can be the result of the expansion of a call to a
9501 -- dispatching function, so we also have to check class-wideness of the
9502 -- type of the expression's original node.
9505 or else
9509 then
9513 -- If the target type is unconstrained, then we reset the type of the
9514 -- result from the type of the expression. For other cases, the actual
9515 -- subtype of the expression is the target type.
9519 then
9526 -- If we still have a qualified expression after the static evaluation,
9527 -- then apply a scalar range check if needed. The reason that we do this
9528 -- after the Eval call is that otherwise, the application of the range
9529 -- check may convert an illegal static expression and result in warning
9530 -- rather than giving an error (e.g Integer'(Integer'Last + 1)).
9536 -- Finally, check whether a predicate applies to the target type. This
9537 -- comes from AI12-0100. As for type conversions, check the enclosing
9538 -- context to prevent an infinite expansion.
9544 or else
9546 then
9549 -- In the case of a qualified expression in an allocator, the check
9550 -- is applied when expanding the allocator, so avoid redundant check.
9554 then
9560 ------------------------------
9561 -- Resolve_Raise_Expression --
9562 ------------------------------
9565 begin
9569 else
9574 -------------------
9575 -- Resolve_Range --
9576 -------------------
9583 -- Returns True if N is of the form X'First .. X'Last where X is the
9584 -- same entity for both attributes.
9586 --------------------
9587 -- First_Last_Ref --
9588 --------------------
9594 begin
9599 then
9600 declare
9603 begin
9607 then
9616 -- Start of processing for Resolve_Range
9618 begin
9623 -- Check for inappropriate range on unordered enumeration type
9627 -- Exclude X'First .. X'Last if X is the same entity for both
9629 and then not First_Last_Ref
9630 then
9632 Error_Msg_NE
9639 -- We have to check the bounds for being within the base range as
9640 -- required for a non-static context. Normally this is automatic and
9641 -- done as part of evaluating expressions, but the N_Range node is an
9642 -- exception, since in GNAT we consider this node to be a subexpression,
9643 -- even though in Ada it is not. The circuit in Sem_Eval could check for
9644 -- this, but that would put the test on the main evaluation path for
9645 -- expressions.
9650 -- Check for an ambiguous range over character literals. This will
9651 -- happen with a membership test involving only literals.
9659 -- If bounds are static, constant-fold them, so size computations are
9660 -- identical between front-end and back-end. Do not perform this
9661 -- transformation while analyzing generic units, as type information
9662 -- would be lost when reanalyzing the constant node in the instance.
9675 --------------------------
9676 -- Resolve_Real_Literal --
9677 --------------------------
9682 begin
9683 -- Special processing for fixed-point literals to make sure that the
9684 -- value is an exact multiple of small where this is required. We skip
9685 -- this for the universal real case, and also for generic types.
9691 then
9692 declare
9699 begin
9700 -- Case of literal is not an exact multiple of the Small
9704 -- For a source program literal for a decimal fixed-point type,
9705 -- this is statically illegal (RM 4.9(36)).
9710 then
9714 -- Generate a warning if literal from source
9717 and then Warn_On_Bad_Fixed_Value
9718 then
9719 Error_Msg_N
9721 N);
9724 -- Replace literal by a value that is the exact representation
9725 -- of a value of the type, i.e. a multiple of the small value,
9726 -- by truncation, since Machine_Rounds is false for all GNAT
9727 -- fixed-point types (RM 4.9(38)).
9737 -- In all cases, set the corresponding integer field
9743 -- Now replace the actual type by the expected type as usual
9749 -----------------------
9750 -- Resolve_Reference --
9751 -----------------------
9756 begin
9757 -- Replace general access with specific type
9765 -- If we are taking the reference of a volatile entity, then treat it as
9766 -- a potential modification of this entity. This is too conservative,
9767 -- but necessary because remove side effects can cause transformations
9768 -- of normal assignments into reference sequences that otherwise fail to
9769 -- notice the modification.
9776 --------------------------------
9777 -- Resolve_Selected_Component --
9778 --------------------------------
9793 -- Check whether this is the initialization of a component within an
9794 -- init proc (by assignment or call to another init proc). If true,
9795 -- there is no need for a discriminant check.
9797 --------------------
9798 -- Init_Component --
9799 --------------------
9802 begin
9803 return Inside_Init_Proc
9809 -- Start of processing for Resolve_Selected_Component
9811 begin
9814 -- Use the context type to select the prefix that has a selector
9815 -- of the correct name and type.
9823 else
9827 -- Locate selected component. For a private prefix the selector
9828 -- can denote a discriminant.
9832 -- The visible components of a class-wide type are those of
9833 -- the root type.
9843 then
9850 else
9854 Error_Msg_N
9859 else
9862 -- There may be an implicit dereference. Retrieve
9863 -- designated record type.
9867 else
9873 -- Resolution chooses the new interpretation.
9874 -- Find the component with the right name.
9879 loop
9896 -- There must be a legal interpretation at this point
9903 else
9904 -- Resolve prefix with its type
9909 -- Generate cross-reference. We needed to wait until full overloading
9910 -- resolution was complete to do this, since otherwise we can't tell if
9911 -- we are an lvalue or not.
9915 else
9919 -- If prefix is an access type, the node will be transformed into an
9920 -- explicit dereference during expansion. The type of the node is the
9921 -- designated type of that of the prefix.
9926 else
9930 -- Set flag for expander if discriminant check required on a component
9931 -- appearing within a variant.
9937 and then
9940 and then not Init_Component
9941 then
9949 -- If the prefix is a record conversion, this may be a renamed
9950 -- discriminant whose bounds differ from those of the original
9951 -- one, so we must ensure that a range check is performed.
9956 then
9960 -- Note: No Eval processing is required, because the prefix is of a
9961 -- record type, or protected type, and neither can possibly be static.
9963 -- If the record type is atomic, and the component is non-atomic, then
9964 -- this is worth a warning, since we have a situation where the access
9965 -- to the component may cause extra read/writes of the atomic array
9966 -- object, or partial word accesses, both of which may be unexpected.
9972 then
9973 Error_Msg_N
9976 Error_Msg_N
9984 -------------------
9985 -- Resolve_Shift --
9986 -------------------
9993 begin
9994 -- We do the resolution using the base type, because intermediate values
9995 -- in expressions always are of the base type, not a subtype of it.
10008 ---------------------------
10009 -- Resolve_Short_Circuit --
10010 ---------------------------
10017 begin
10018 -- Ensure all actions associated with the left operand (e.g.
10019 -- finalization of transient objects) are fully evaluated locally within
10020 -- an expression with actions. This is particularly helpful for coverage
10021 -- analysis. However this should not happen in generics or if option
10022 -- Minimize_Expression_With_Actions is set.
10025 declare
10027 begin
10035 -- Set Comes_From_Source on L to preserve warnings for unset
10036 -- reference.
10045 -- Check for issuing warning for always False assert/check, this happens
10046 -- when assertions are turned off, in which case the pragma Assert/Check
10047 -- was transformed into:
10049 -- if False and then <condition> then ...
10051 -- and we detect this pattern
10053 if Warn_On_Assertion_Failure
10060 then
10061 declare
10064 begin
10065 -- Special handling of Asssert pragma
10069 then
10070 declare
10072 Original_Node
10073 (Expression
10076 begin
10077 -- Don't warn if original condition is explicit False,
10078 -- since obviously the failure is expected in this case.
10082 then
10085 -- Issue warning. We do not want the deletion of the
10086 -- IF/AND-THEN to take this message with it. We achieve this
10087 -- by making sure that the expanded code points to the Sloc
10088 -- of the expression, not the original pragma.
10090 else
10091 -- Note: Use Error_Msg_F here rather than Error_Msg_N.
10092 -- The source location of the expression is not usually
10093 -- the best choice here. For example, it gets located on
10094 -- the last AND keyword in a chain of boolean expressiond
10095 -- AND'ed together. It is best to put the message on the
10096 -- first character of the assertion, which is the effect
10097 -- of the First_Node call here.
10099 Error_Msg_F
10101 Expression
10106 -- Similar processing for Check pragma
10110 then
10111 -- Don't want to warn if original condition is explicit False
10113 declare
10115 Original_Node
10116 (Expression
10118 begin
10121 then
10124 -- Post warning
10126 else
10127 -- Again use Error_Msg_F rather than Error_Msg_N, see
10128 -- comment above for an explanation of why we do this.
10130 Error_Msg_F
10132 Expression
10140 -- Continue with processing of short circuit
10149 -------------------
10150 -- Resolve_Slice --
10151 -------------------
10160 begin
10163 -- Use the context type to select the prefix that yields the correct
10164 -- array type.
10166 declare
10173 begin
10181 then
10189 else
10194 else
10205 else
10215 -- If the prefix is an access to an unconstrained array, we must use
10216 -- the actual subtype of the object to perform the index checks. The
10217 -- object denoted by the prefix is implicit in the node, so we build
10218 -- an explicit representation for it in order to compute the actual
10219 -- subtype.
10224 declare
10228 begin
10239 then
10242 -- If the name is a selected component that depends on discriminants,
10243 -- build an actual subtype for it. This can happen only when the name
10244 -- itself is overloaded; otherwise the actual subtype is created when
10245 -- the selected component is analyzed.
10248 and then Full_Analysis
10250 then
10251 declare
10254 begin
10259 -- Maybe this should just be "else", instead of checking for the
10260 -- specific case of slice??? This is needed for the case where the
10261 -- prefix is an Image attribute, which gets expanded to a slice, and so
10262 -- has a constrained subtype which we want to use for the slice range
10263 -- check applied below (the range check won't get done if the
10264 -- unconstrained subtype of the 'Image is used).
10270 -- Obtain the type of the array index
10274 else
10278 -- If name was overloaded, set slice type correctly now
10282 -- Handle the generation of a range check that compares the array index
10283 -- against the discrete_range. The check is not applied to internally
10284 -- built nodes associated with the expansion of dispatch tables. Check
10285 -- that Ada.Tags has already been loaded to avoid extra dependencies on
10286 -- the unit.
10288 if Tagged_Type_Expansion
10294 then
10297 -- The discrete_range is specified by a subtype indication. Create a
10298 -- shallow copy and inherit the type, parent and source location from
10299 -- the discrete_range. This ensures that the range check is inserted
10300 -- relative to the slice and that the runtime exception points to the
10301 -- proper construct.
10310 -- The discrete_range is a regular range. Resolve the bounds and remove
10311 -- their side effects.
10313 else
10330 -- Check bad use of type with predicates
10332 declare
10335 begin
10338 then
10340 else
10345 Bad_Predicated_Subtype_Use
10350 -- Otherwise here is where we check suspicious indexes
10361 ----------------------------
10362 -- Resolve_String_Literal --
10363 ----------------------------
10374 begin
10375 -- For a string appearing in a concatenation, defer creation of the
10376 -- string_literal_subtype until the end of the resolution of the
10377 -- concatenation, because the literal may be constant-folded away. This
10378 -- is a useful optimization for long concatenation expressions.
10380 -- If the string is an aggregate built for a single character (which
10381 -- happens in a non-static context) or a is null string to which special
10382 -- checks may apply, we build the subtype. Wide strings must also get a
10383 -- string subtype if they come from a one character aggregate. Strings
10384 -- generated by attributes might be static, but it is often hard to
10385 -- determine whether the enclosing context is static, so we generate
10386 -- subtypes for them as well, thus losing some rarer optimizations ???
10387 -- Same for strings that come from a static conversion.
10389 Need_Check :=
10398 -- If the resolving type is itself a string literal subtype, we can just
10399 -- reuse it, since there is no point in creating another.
10405 and then not Need_Check
10407 N_Attribute_Reference,
10408 N_Qualified_Expression,
10409 N_Type_Conversion)
10410 then
10413 -- Do not generate a string literal subtype for the default expression
10414 -- of a formal parameter in GNATprove mode. This is because the string
10415 -- subtype is associated with the freezing actions of the subprogram,
10416 -- however freezing is disabled in GNATprove mode and as a result the
10417 -- subtype is unavailable.
10419 elsif GNATprove_Mode
10421 then
10424 -- Otherwise we must create a string literal subtype. Note that the
10425 -- whole idea of string literal subtypes is simply to avoid the need
10426 -- for building a full fledged array subtype for each literal.
10428 else
10434 or else Need_Check
10435 then
10442 then
10448 -- The validity of a null string has been checked in the call to
10449 -- Eval_String_Literal.
10454 -- Always accept string literal with component type Any_Character, which
10455 -- occurs in error situations and in comparisons of literals, both of
10456 -- which should accept all literals.
10461 -- If the type is bit-packed, then we always transform the string
10462 -- literal into a full fledged aggregate.
10467 -- Deal with cases of Wide_Wide_String, Wide_String, and String
10469 else
10470 -- For Standard.Wide_Wide_String, or any other type whose component
10471 -- type is Standard.Wide_Wide_Character, we know that all the
10472 -- characters in the string must be acceptable, since the parser
10473 -- accepted the characters as valid character literals.
10478 -- For the case of Standard.String, or any other type whose component
10479 -- type is Standard.Character, we must make sure that there are no
10480 -- wide characters in the string, i.e. that it is entirely composed
10481 -- of characters in range of type Character.
10483 -- If the string literal is the result of a static concatenation, the
10484 -- test has already been performed on the components, and need not be
10485 -- repeated.
10489 then
10493 -- If we are out of range, post error. This is one of the
10494 -- very few places that we place the flag in the middle of
10495 -- a token, right under the offending wide character. Not
10496 -- quite clear if this is right wrt wide character encoding
10497 -- sequences, but it's only an error message.
10499 Error_Msg
10506 -- For the case of Standard.Wide_String, or any other type whose
10507 -- component type is Standard.Wide_Character, we must make sure that
10508 -- there are no wide characters in the string, i.e. that it is
10509 -- entirely composed of characters in range of type Wide_Character.
10511 -- If the string literal is the result of a static concatenation,
10512 -- the test has already been performed on the components, and need
10513 -- not be repeated.
10517 then
10521 -- If we are out of range, post error. This is one of the
10522 -- very few places that we place the flag in the middle of
10523 -- a token, right under the offending wide character.
10525 -- This is not quite right, because characters in general
10526 -- will take more than one character position ???
10528 Error_Msg
10535 -- If the root type is not a standard character, then we will convert
10536 -- the string into an aggregate and will let the aggregate code do
10537 -- the checking. Standard Wide_Wide_Character is also OK here.
10539 else
10543 -- See if the component type of the array corresponding to the string
10544 -- has compile time known bounds. If yes we can directly check
10545 -- whether the evaluation of the string will raise constraint error.
10546 -- Otherwise we need to transform the string literal into the
10547 -- corresponding character aggregate and let the aggregate code do
10548 -- the checking.
10552 -- Check for the case of full range, where we are definitely OK
10558 -- Here the range is not the complete base type range, so check
10560 declare
10568 begin
10571 then
10577 then
10578 Apply_Compile_Time_Constraint_Error
10580 CE_Range_Check_Failed,
10591 -- If we got here we meed to transform the string literal into the
10592 -- equivalent qualified positional array aggregate. This is rather
10593 -- heavy artillery for this situation, but it is hard work to avoid.
10595 declare
10600 begin
10601 -- Build the character literals, we give them source locations that
10602 -- correspond to the string positions, which is a bit tricky given
10603 -- the possible presence of wide character escape sequences.
10617 -- Should we have a call to Skip_Wide here ???
10619 -- ??? else
10620 -- Skip_Wide (P);
10628 Expression =>
10635 -----------------------------
10636 -- Resolve_Type_Conversion --
10637 -----------------------------
10649 -- Set to False to suppress cases where we want to suppress the test
10650 -- for redundancy to avoid possible false positives on this warning.
10652 begin
10653 if not Conv_OK
10655 then
10659 -- If the Operand Etype is Universal_Fixed, then the conversion is
10660 -- never redundant. We need this check because by the time we have
10661 -- finished the rather complex transformation, the conversion looks
10662 -- redundant when it is not.
10667 -- If the operand is marked as Any_Fixed, then special processing is
10668 -- required. This is also a case where we suppress the test for a
10669 -- redundant conversion, since most certainly it is not redundant.
10674 -- Mixed-mode operation involving a literal. Context must be a fixed
10675 -- type which is applied to the literal subsequently.
10683 or else
10685 then
10686 -- Return if expression is ambiguous
10691 -- If nothing else, the available fixed type is Duration
10693 else
10697 -- Resolve the real operand with largest available precision
10701 else
10707 -- If the operand is a literal (it could be a non-static and
10708 -- illegal exponentiation) check whether the use of Duration
10709 -- is potentially inaccurate.
10714 then
10715 Error_Msg_N
10718 Error_Msg_N
10725 then
10728 else
10737 -- In SPARK, a type conversion between array types should be restricted
10738 -- to types which have matching static bounds.
10740 -- Protect call to Matching_Static_Array_Bounds to avoid costly
10741 -- operation if not needed.
10748 then
10749 Check_SPARK_05_Restriction
10753 -- In formal mode, the operand of an ancestor type conversion must be an
10754 -- object (not an expression).
10762 then
10768 -- Note: we do the Eval_Type_Conversion call before applying the
10769 -- required checks for a subtype conversion. This is important, since
10770 -- both are prepared under certain circumstances to change the type
10771 -- conversion to a constraint error node, but in the case of
10772 -- Eval_Type_Conversion this may reflect an illegality in the static
10773 -- case, and we would miss the illegality (getting only a warning
10774 -- message), if we applied the type conversion checks first.
10778 -- Even when evaluation is not possible, we may be able to simplify the
10779 -- conversion or its expression. This needs to be done before applying
10780 -- checks, since otherwise the checks may use the original expression
10781 -- and defeat the simplifications. This is specifically the case for
10782 -- elimination of the floating-point Truncation attribute in
10783 -- float-to-int conversions.
10787 -- If after evaluation we still have a type conversion, then we may need
10788 -- to apply checks required for a subtype conversion.
10790 -- Skip these type conversion checks if universal fixed operands
10791 -- operands involved, since range checks are handled separately for
10792 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
10798 then
10802 -- Issue warning for conversion of simple object to its own type. We
10803 -- have to test the original nodes, since they may have been rewritten
10804 -- by various optimizations.
10808 -- Here we test for a redundant conversion if the warning mode is
10809 -- active (and was not locally reset), and we have a type conversion
10810 -- from source not appearing in a generic instance.
10812 if Test_Redundant
10815 and then not In_Instance
10816 then
10820 -- If the node is part of a larger expression, the Target_Type
10821 -- may not be the original type of the node if the context is a
10822 -- condition. Recover original type to see if conversion is needed.
10826 then
10830 -- If we have an entity name, then give the warning if the entity
10831 -- is the right type, or if it is a loop parameter covered by the
10832 -- original type (that's needed because loop parameters have an
10833 -- odd subtype coming from the bounds).
10836 and then
10838 or else
10842 -- If not an entity, then type of expression must match
10845 then
10846 -- One more check, do not give warning if the analyzed conversion
10847 -- has an expression with non-static bounds, and the bounds of the
10848 -- target are static. This avoids junk warnings in cases where the
10849 -- conversion is necessary to establish staticness, for example in
10850 -- a case statement.
10854 then
10857 -- Finally, if this type conversion occurs in a context requiring
10858 -- a prefix, and the expression is a qualified expression then the
10859 -- type conversion is not redundant, since a qualified expression
10860 -- is not a prefix, whereas a type conversion is. For example, "X
10861 -- := T'(Funx(...)).Y;" is illegal because a selected component
10862 -- requires a prefix, but a type conversion makes it legal: "X :=
10863 -- T(T'(Funx(...))).Y;"
10865 -- In Ada 2012, a qualified expression is a name, so this idiom is
10866 -- no longer needed, but we still suppress the warning because it
10867 -- seems unfriendly for warnings to pop up when you switch to the
10868 -- newer language version.
10872 N_Indexed_Component,
10873 N_Selected_Component,
10874 N_Slice,
10875 N_Explicit_Dereference)
10876 then
10879 -- Never warn on conversion to Long_Long_Integer'Base since
10880 -- that is most likely an artifact of the extended overflow
10881 -- checking and comes from complex expanded code.
10886 -- Here we give the redundant conversion warning. If it is an
10887 -- entity, give the name of the entity in the message. If not,
10888 -- just mention the expression.
10890 -- Shoudn't we test Warn_On_Redundant_Constructs here ???
10892 else
10895 Error_Msg_NE -- CODEFIX
10898 else
10899 Error_Msg_NE
10907 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
10908 -- No need to perform any interface conversion if the type of the
10909 -- expression coincides with the target type.
10912 and then Expander_Active
10914 then
10915 declare
10919 begin
10920 -- If the type of the operand is a limited view, use nonlimited
10921 -- view when available. If it is a class-wide type, recover the
10922 -- class-wide type of the nonlimited view.
10926 then
10942 -- Conversion from interface type
10946 -- Ada 2005 (AI-217): Handle entities from limited views
10950 Error_Msg_NE -- CODEFIX
10953 Error_Msg_N
10955 N);
10958 and then not
10961 then
10963 Error_Msg_NE -- CODEFIX
10966 Error_Msg_N
10968 N);
10970 else
10974 -- Conversion to interface type
10978 -- Handle subtypes
10985 or else Interface_Present_In_Ancestor
10988 then
10990 else
10993 Error_Msg_N
11001 -- Ada 2012: if target type has predicates, the result requires a
11002 -- predicate check. If the context is a call to another predicate
11003 -- check we must prevent infinite recursion.
11009 or else
11011 then
11014 else
11019 -- If at this stage we have a real to integer conversion, make sure
11020 -- that the Do_Range_Check flag is set, because such conversions in
11021 -- general need a range check. We only need this if expansion is off
11022 -- or we are in GNATProve mode.
11028 then
11032 -- Generating C code a type conversion of an access to constrained
11033 -- array type to access to unconstrained array type involves building
11034 -- a fat pointer which in general cannot be generated on the fly. We
11035 -- remove side effects in order to store the result of the conversion
11036 -- into a temporary.
11038 if Modify_Tree_For_C
11045 then
11050 ----------------------
11051 -- Resolve_Unary_Op --
11052 ----------------------
11061 begin
11064 Check_SPARK_05_Restriction
11068 -- Deal with intrinsic unary operators
11074 then
11079 -- Deal with universal cases
11082 or else
11084 then
11091 -- Generate warning for expressions like abs (x mod 2)
11093 if Warn_On_Redundant_Constructs
11095 then
11099 Error_Msg_N -- CODEFIX
11104 -- Deal with reference generation
11111 -- Set overflow checking bit. Much cleverer code needed here eventually
11112 -- and perhaps the Resolve routines should be separated for the various
11113 -- arithmetic operations, since they will need different processing ???
11121 -- Generate warning for expressions like -5 mod 3 for integers. No need
11122 -- to worry in the floating-point case, since parens do not affect the
11123 -- result so there is no point in giving in a warning.
11125 declare
11134 begin
11135 if Warn_On_Questionable_Missing_Parens
11139 then
11142 -- We are looking for cases where the right operand is not
11143 -- parenthesized, and is a binary operator, multiply, divide, or
11144 -- mod. These are the cases where the grouping can affect results.
11148 then
11149 -- For mod, we always give the warning, since the value is
11150 -- affected by the parenthesization (e.g. (-5) mod 315 /=
11151 -- -(5 mod 315)). But for the other cases, the only concern is
11152 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
11153 -- overflows, but (-2) * 64 does not). So we try to give the
11154 -- message only when overflow is possible.
11158 then
11163 else
11169 else
11173 -- Note that the test below is deliberately excluding the
11174 -- largest negative number, since that is a potentially
11175 -- troublesome case (e.g. -2 * x, where the result is the
11176 -- largest negative integer has an overflow with 2 * x).
11183 -- For the multiplication case, the only case we have to worry
11184 -- about is when (-a)*b is exactly the largest negative number
11185 -- so that -(a*b) can cause overflow. This can only happen if
11186 -- a is a power of 2, and more generally if any operand is a
11187 -- constant that is not a power of 2, then the parentheses
11188 -- cannot affect whether overflow occurs. We only bother to
11189 -- test the left most operand
11191 -- Loop looking at left operands for one that has known value
11198 -- Operand value of 0 or 1 skips warning
11203 -- Otherwise check power of 2, if power of 2, warn, if
11204 -- anything else, skip warning.
11206 else
11210 else
11219 -- Keep looking at left operands
11224 -- For rem or "/" we can only have a problematic situation
11225 -- if the divisor has a value of minus one or one. Otherwise
11226 -- overflow is impossible (divisor > 1) or we have a case of
11227 -- division by zero in any case.
11232 then
11236 -- If we fall through warning should be issued
11238 -- Shouldn't we test Warn_On_Questionable_Missing_Parens ???
11240 Error_Msg_N
11247 ----------------------------------
11248 -- Resolve_Unchecked_Expression --
11249 ----------------------------------
11251 procedure Resolve_Unchecked_Expression
11254 is
11255 begin
11260 ---------------------------------------
11261 -- Resolve_Unchecked_Type_Conversion --
11262 ---------------------------------------
11264 procedure Resolve_Unchecked_Type_Conversion
11267 is
11273 begin
11274 -- Resolve operand using its own type
11278 -- In an inlined context, the unchecked conversion may be applied
11279 -- to a literal, in which case its type is the type of the context.
11280 -- (In other contexts conversions cannot apply to literals).
11282 if In_Inlined_Body
11286 then
11294 ------------------------------
11295 -- Rewrite_Operator_As_Call --
11296 ------------------------------
11303 begin
11310 New_N :=
11321 ------------------------------
11322 -- Rewrite_Renamed_Operator --
11323 ------------------------------
11325 procedure Rewrite_Renamed_Operator
11329 is
11334 begin
11335 -- Do not perform this transformation within a pre/postcondition,
11336 -- because the expression will be re-analyzed, and the transformation
11337 -- might affect the visibility of the operator, e.g. in an instance.
11338 -- Note that fully analyzed and expanded pre/postconditions appear as
11339 -- pragma Check equivalents.
11345 -- Rewrite the operator node using the real operator, not its renaming.
11346 -- Exclude user-defined intrinsic operations of the same name, which are
11347 -- treated separately and rewritten as calls.
11356 -- Indicate that both the original entity and its renaming are
11357 -- referenced at this point.
11368 -- If the context type is private, add the appropriate conversions so
11369 -- that the operator is applied to the full view. This is done in the
11370 -- routines that resolve intrinsic operators.
11374 when N_Op_Add
11375 | N_Op_Divide
11376 | N_Op_Expon
11377 | N_Op_Mod
11378 | N_Op_Multiply
11379 | N_Op_Rem
11380 | N_Op_Subtract
11381 =>
11384 when N_Op_Abs
11385 | N_Op_Minus
11386 | N_Op_Plus
11387 =>
11397 -- Operator renames a user-defined operator of the same name. Use the
11398 -- original operator in the node, which is the one Gigi knows about.
11405 -----------------------
11406 -- Set_Slice_Subtype --
11407 -----------------------
11409 -- Build an implicit subtype declaration to represent the type delivered by
11410 -- the slice. This is an abbreviated version of an array subtype. We define
11411 -- an index subtype for the slice, using either the subtype name or the
11412 -- discrete range of the slice. To be consistent with index usage elsewhere
11413 -- we create a list header to hold the single index. This list is not
11414 -- otherwise attached to the syntax tree.
11425 begin
11431 else
11432 -- We force the evaluation of a range. This is definitely needed in
11433 -- the renamed case, and seems safer to do unconditionally. Note in
11434 -- any case that since we will create and insert an Itype referring
11435 -- to this range, we must make sure any side effect removal actions
11436 -- are inserted before the Itype definition.
11442 -- If the discrete range is given by a subtype indication, the
11443 -- type of the slice is the base of the subtype mark.
11446 declare
11448 begin
11457 -- Take a new copy of Drange (where bounds have been rewritten to
11458 -- reference side-effect-free names). Using a separate tree ensures
11459 -- that further expansion (e.g. while rewriting a slice assignment
11460 -- into a FOR loop) does not attempt to remove side effects on the
11461 -- bounds again (which would cause the bounds in the index subtype
11462 -- definition to refer to temporaries before they are defined) (the
11463 -- reason is that some names are considered side effect free here
11464 -- for the subtype, but not in the context of a loop iteration
11465 -- scheme).
11486 -- The Etype of the existing Slice node is reset to this slice subtype.
11487 -- Its bounds are obtained from its first index.
11491 -- For packed slice subtypes, freeze immediately (except in the case of
11492 -- being in a "spec expression" where we never freeze when we first see
11493 -- the expression).
11498 -- For all other cases insert an itype reference in the slice's actions
11499 -- so that the itype is frozen at the proper place in the tree (i.e. at
11500 -- the point where actions for the slice are analyzed). Note that this
11501 -- is different from freezing the itype immediately, which might be
11502 -- premature (e.g. if the slice is within a transient scope). This needs
11503 -- to be done only if expansion is enabled.
11510 --------------------------------
11511 -- Set_String_Literal_Subtype --
11512 --------------------------------
11520 begin
11532 -- The low bound is set from the low bound of the corresponding index
11533 -- type. Note that we do not store the high bound in the string literal
11534 -- subtype, but it can be deduced if necessary from the length and the
11535 -- low bound.
11540 -- If the lower bound is not static we create a range for the string
11541 -- literal, using the index type and the known length of the literal.
11542 -- The index type is not necessarily Positive, so the upper bound is
11543 -- computed as T'Val (T'Pos (Low_Bound) + L - 1).
11545 else
11546 declare
11552 Prefix =>
11556 Left_Opnd =>
11559 Prefix =>
11561 Expressions =>
11563 Right_Opnd =>
11572 begin
11574 Set_String_Literal_Low_Bound
11577 else
11578 -- If the index type is an enumeration type, build bounds
11579 -- expression with attributes.
11581 Set_String_Literal_Low_Bound
11585 Prefix =>
11592 -- Build bona fide subtype for the string, and wrap it in an
11593 -- unchecked conversion, because the backend expects the
11594 -- String_Literal_Subtype to have a static lower bound.
11596 Index_Subtype :=
11603 -- In the context, the Index_Type may already have a constraint,
11604 -- so use common base type on string subtype. The base type may
11605 -- be used when generating attributes of the string, for example
11606 -- in the context of a slice assignment.
11631 ------------------------------
11632 -- Simplify_Type_Conversion --
11633 ------------------------------
11636 begin
11638 declare
11643 begin
11644 -- Special processing if the conversion is the expression of a
11645 -- Rounding or Truncation attribute reference. In this case we
11646 -- replace:
11648 -- ityp (ftyp'Rounding (x)) or ityp (ftyp'Truncation (x))
11650 -- by
11652 -- ityp (x)
11654 -- with the Float_Truncate flag set to False or True respectively,
11655 -- which is more efficient.
11658 and then
11664 Name_Truncation)
11665 then
11666 declare
11669 begin
11679 -----------------------------
11680 -- Unique_Fixed_Point_Type --
11681 -----------------------------
11690 -- Give error messages for true ambiguity. Messages are posted on node
11691 -- N, and entities T1, T2 are the possible interpretations.
11693 -----------------------
11694 -- Fixed_Point_Error --
11695 -----------------------
11698 begin
11704 -- Start of processing for Unique_Fixed_Point_Type
11706 begin
11707 -- The operations on Duration are visible, so Duration is always a
11708 -- possible interpretation.
11712 -- Look for fixed-point types in enclosing scopes
11721 then
11723 Fixed_Point_Error;
11725 else
11736 -- Look for visible fixed type declarations in the context
11747 then
11749 Fixed_Point_Error;
11751 else
11764 Error_Msg_NE
11766 else
11767 Error_Msg_NE
11774 ----------------------
11775 -- Valid_Conversion --
11776 ----------------------
11778 function Valid_Conversion
11783 is
11788 function Conversion_Check
11791 -- Little routine to post Msg if Valid is False, returns Valid value
11794 -- If Report_Errs, then calls Errout.Error_Msg_N with its arguments
11796 procedure Conversion_Error_NE
11800 -- If Report_Errs, then calls Errout.Error_Msg_NE with its arguments
11802 function Valid_Tagged_Conversion
11805 -- Specifically test for validity of tagged conversions
11808 -- Check index and component conformance, and accessibility levels if
11809 -- the component types are anonymous access types (Ada 2005).
11811 ----------------------
11812 -- Conversion_Check --
11813 ----------------------
11815 function Conversion_Check
11818 is
11819 begin
11820 if not Valid
11822 -- A generic unit has already been analyzed and we have verified
11823 -- that a particular conversion is OK in that context. Since the
11824 -- instance is reanalyzed without relying on the relationships
11825 -- established during the analysis of the generic, it is possible
11826 -- to end up with inconsistent views of private types. Do not emit
11827 -- the error message in such cases. The rest of the machinery in
11828 -- Valid_Conversion still ensures the proper compatibility of
11829 -- target and operand types.
11831 and then not In_Instance
11832 then
11839 ------------------------
11840 -- Conversion_Error_N --
11841 ------------------------
11844 begin
11850 -------------------------
11851 -- Conversion_Error_NE --
11852 -------------------------
11854 procedure Conversion_Error_NE
11858 is
11859 begin
11865 ----------------------------
11866 -- Valid_Array_Conversion --
11867 ----------------------------
11884 begin
11885 -- Error if wrong number of dimensions
11887 if
11889 then
11890 Conversion_Error_N
11894 -- Number of dimensions matches
11896 else
11897 -- Loop through indexes of the two arrays
11905 -- Error if index types are incompatible
11911 then
11912 Conversion_Error_N
11914 Operand);
11922 -- If component types have same base type, all set
11927 -- Here if base types of components are not the same. The only
11928 -- time this is allowed is if we have anonymous access types.
11930 -- The conversion of arrays of anonymous access types can lead
11931 -- to dangling pointers. AI-392 formalizes the accessibility
11932 -- checks that must be applied to such conversions to prevent
11933 -- out-of-scope references.
11935 elsif Ekind_In
11937 E_Anonymous_Access_Subprogram_Type)
11939 and then
11941 then
11944 then
11947 Conversion_Error_N
11957 -- Conversion not allowed because of accessibility levels
11959 else
11960 Conversion_Error_N
11966 else
11970 -- All other cases where component base types do not match
11972 else
11973 Conversion_Error_N
11975 Operand);
11979 -- Check that component subtypes statically match. For numeric
11980 -- types this means that both must be either constrained or
11981 -- unconstrained. For enumeration types the bounds must match.
11982 -- All of this is checked in Subtypes_Statically_Match.
11984 if not Subtypes_Statically_Match
11986 then
11987 Conversion_Error_N
11996 -----------------------------
11997 -- Valid_Tagged_Conversion --
11998 -----------------------------
12000 function Valid_Tagged_Conversion
12003 is
12004 begin
12005 -- Upward conversions are allowed (RM 4.6(22))
12009 then
12012 -- Downward conversion are allowed if the operand is class-wide
12013 -- (RM 4.6(23)).
12017 then
12022 then
12023 return
12027 -- Ada 2005 (AI-251): The conversion to/from interface types is
12028 -- always valid. The types involved may be class-wide (sub)types.
12032 then
12035 -- If the operand is a class-wide type obtained through a limited_
12036 -- with clause, and the context includes the nonlimited view, use
12037 -- it to determine whether the conversion is legal.
12043 then
12048 then
12051 else
12052 Conversion_Error_NE
12059 -- Start of processing for Valid_Conversion
12061 begin
12065 declare
12073 begin
12074 -- Remove procedure calls, which syntactically cannot appear in
12075 -- this context, but which cannot be removed by type checking,
12076 -- because the context does not impose a type.
12078 -- The node may be labelled overloaded, but still contain only one
12079 -- interpretation because others were discarded earlier. If this
12080 -- is the case, retain the single interpretation if legal.
12088 then
12089 -- More than one candidate interpretation is available
12097 -- When compiling for a system where Address is of a visible
12098 -- integer type, spurious ambiguities can be produced when
12099 -- arithmetic operations have a literal operand and return
12100 -- System.Address or a descendant of it. These ambiguities
12101 -- are usually resolved by the context, but for conversions
12102 -- there is no context type and the removal of the spurious
12103 -- operations must be done explicitly here.
12105 if not Address_Is_Private
12107 then
12132 Conversion_Error_N
12135 -- If the interpretation involves a standard operator, use
12136 -- the location of the type, which may be user-defined.
12140 else
12144 Conversion_Error_N -- CODEFIX
12149 else
12153 Conversion_Error_N -- CODEFIX
12165 -- Deal with conversion of integer type to address if the pragma
12166 -- Allow_Integer_Address is in effect. We convert the conversion to
12167 -- an unchecked conversion in this case and we are all done.
12175 -- If we are within a child unit, check whether the type of the
12176 -- expression has an ancestor in a parent unit, in which case it
12177 -- belongs to its derivation class even if the ancestor is private.
12178 -- See RM 7.3.1 (5.2/3).
12182 -- Numeric types
12186 -- A universal fixed expression can be converted to any numeric type
12191 -- Also no need to check when in an instance or inlined body, because
12192 -- the legality has been established when the template was analyzed.
12193 -- Furthermore, numeric conversions may occur where only a private
12194 -- view of the operand type is visible at the instantiation point.
12195 -- This results in a spurious error if we check that the operand type
12196 -- is a numeric type.
12198 -- Note: in a previous version of this unit, the following tests were
12199 -- applied only for generated code (Comes_From_Source set to False),
12200 -- but in fact the test is required for source code as well, since
12201 -- this situation can arise in source code.
12206 -- Otherwise we need the conversion check
12208 else
12209 return Conversion_Check
12211 or else
12217 -- Array types
12223 then
12224 Conversion_Error_N
12228 else
12232 -- Ada 2005 (AI-251): Internally generated conversions of access to
12233 -- interface types added to force the displacement of the pointer to
12234 -- reference the corresponding dispatch table.
12239 then
12242 -- Ada 2005 (AI-251): Anonymous access types where target references an
12243 -- interface type.
12247 E_Anonymous_Access_Type)
12249 then
12250 -- Check the static accessibility rule of 4.6(17). Note that the
12251 -- check is not enforced when within an instance body, since the
12252 -- RM requires such cases to be caught at run time.
12254 -- If the operand is a rewriting of an allocator no check is needed
12255 -- because there are no accessibility issues.
12263 then
12264 -- In an instance, this is a run-time check, but one we know
12265 -- will fail, so generate an appropriate warning. The raise
12266 -- will be generated by Expand_N_Type_Conversion.
12270 Conversion_Error_N
12272 Operand);
12275 else
12276 Conversion_Error_N
12278 Operand);
12282 -- Special accessibility checks are needed in the case of access
12283 -- discriminants declared for a limited type.
12287 then
12288 -- When the operand is a selected access discriminant the check
12289 -- needs to be made against the level of the object denoted by
12290 -- the prefix of the selected name (Object_Access_Level handles
12291 -- checking the prefix of the operand for this case).
12296 then
12297 -- In an instance, this is a run-time check, but one we know
12298 -- will fail, so generate an appropriate warning. The raise
12299 -- will be generated by Expand_N_Type_Conversion.
12303 Conversion_Error_N
12308 -- Real error if not in instance body
12310 else
12311 Conversion_Error_N
12318 -- The case of a reference to an access discriminant from
12319 -- within a limited type declaration (which will appear as
12320 -- a discriminal) is always illegal because the level of the
12321 -- discriminant is considered to be deeper than any (nameable)
12322 -- access type.
12326 and then
12329 then
12330 Conversion_Error_N
12332 Operand);
12340 -- General and anonymous access types
12343 E_Anonymous_Access_Type)
12344 and then
12345 Conversion_Check
12347 and then not
12349 E_Access_Protected_Subprogram_Type),
12351 then
12354 then
12355 Conversion_Error_N
12360 -- Check the static accessibility rule of 4.6(17). Note that the
12361 -- check is not enforced when within an instance body, since the RM
12362 -- requires such cases to be caught at run time.
12367 N_Object_Declaration
12368 then
12369 -- Ada 2012 (AI05-0149): Perform legality checking on implicit
12370 -- conversions from an anonymous access type to a named general
12371 -- access type. Such conversions are not allowed in the case of
12372 -- access parameters and stand-alone objects of an anonymous
12373 -- access type. The implicit conversion case is recognized by
12374 -- testing that Comes_From_Source is False and that it's been
12375 -- rewritten. The Comes_From_Source test isn't sufficient because
12376 -- nodes in inlined calls to predefined library routines can have
12377 -- Comes_From_Source set to False. (Is there a better way to test
12378 -- for implicit conversions???)
12385 then
12388 -- Implicit conversions aren't allowed for objects of an
12389 -- anonymous access type, since such objects have nonstatic
12390 -- levels in Ada 2012.
12393 N_Object_Declaration
12394 then
12395 Conversion_Error_N
12400 -- Implicit conversions aren't allowed for anonymous access
12401 -- parameters. The "not Is_Local_Anonymous_Access_Type" test
12402 -- is done to exclude anonymous access results.
12406 N_Function_Specification,
12407 N_Procedure_Specification)
12408 then
12409 Conversion_Error_N
12414 -- This is a case where there's an enclosing object whose
12415 -- to which the "statically deeper than" relationship does
12416 -- not apply (such as an access discriminant selected from
12417 -- a dereference of an access parameter).
12421 then
12422 Conversion_Error_N
12427 -- In other cases, the level of the operand's type must be
12428 -- statically less deep than that of the target type, else
12429 -- implicit conversion is disallowed (by RM12-8.6(27.1/3)).
12433 then
12434 Conversion_Error_N
12443 then
12444 -- In an instance, this is a run-time check, but one we know
12445 -- will fail, so generate an appropriate warning. The raise
12446 -- will be generated by Expand_N_Type_Conversion.
12450 Conversion_Error_N
12452 Operand);
12455 -- If not in an instance body, this is a real error
12457 else
12458 -- Avoid generation of spurious error message
12461 Conversion_Error_N
12463 Operand);
12469 -- Special accessibility checks are needed in the case of access
12470 -- discriminants declared for a limited type.
12474 then
12475 -- When the operand is a selected access discriminant the check
12476 -- needs to be made against the level of the object denoted by
12477 -- the prefix of the selected name (Object_Access_Level handles
12478 -- checking the prefix of the operand for this case).
12483 then
12484 -- In an instance, this is a run-time check, but one we know
12485 -- will fail, so generate an appropriate warning. The raise
12486 -- will be generated by Expand_N_Type_Conversion.
12490 Conversion_Error_N
12495 -- If not in an instance body, this is a real error
12497 else
12498 Conversion_Error_N
12505 -- The case of a reference to an access discriminant from
12506 -- within a limited type declaration (which will appear as
12507 -- a discriminal) is always illegal because the level of the
12508 -- discriminant is considered to be deeper than any (nameable)
12509 -- access type.
12512 and then
12515 then
12516 Conversion_Error_N
12518 Operand);
12524 -- In the presence of limited_with clauses we have to use nonlimited
12525 -- views, if available.
12529 -- Helper function to handle limited views
12531 --------------------------
12532 -- Full_Designated_Type --
12533 --------------------------
12538 begin
12539 -- Handle the limited view of a type
12543 then
12545 else
12550 -- Local Declarations
12558 -- Start of processing for Check_Limited
12560 begin
12564 else
12566 Conversion_Error_NE
12571 -- Ada 2005 AI-384: legality rule is symmetric in both
12572 -- designated types. The conversion is legal (with possible
12573 -- constraint check) if either designated type is
12574 -- unconstrained.
12577 or else
12579 and then
12582 then
12583 -- Special case, if Value_Size has been used to make the
12584 -- sizes different, the conversion is not allowed even
12585 -- though the subtypes statically match.
12590 then
12591 Conversion_Error_NE
12594 Conversion_Error_NE
12599 -- Normal case where conversion is allowed
12601 else
12605 else
12606 Error_Msg_NE
12614 -- Access to subprogram types. If the operand is an access parameter,
12615 -- the type has a deeper accessibility that any master, and cannot be
12616 -- assigned. We must make an exception if the conversion is part of an
12617 -- assignment and the target is the return object of an extended return
12618 -- statement, because in that case the accessibility check takes place
12619 -- after the return.
12623 -- Note: this test of Opnd_Type is there to prevent entering this
12624 -- branch in the case of a remote access to subprogram type, which
12625 -- is internally represented as an E_Record_Type.
12628 then
12632 and then
12636 then
12637 Conversion_Error_N
12639 Operand);
12640 Conversion_Error_N
12643 Operand);
12645 Error_Msg_NE
12650 -- Check that the designated types are subtype conformant
12656 -- Check the static accessibility rule of 4.6(20)
12660 then
12661 Conversion_Error_N
12663 Operand);
12665 -- Check that if the operand type is declared in a generic body,
12666 -- then the target type must be declared within that same body
12667 -- (enforces last sentence of 4.6(20)).
12670 declare
12676 begin
12683 Conversion_Error_N
12692 -- Remote access to subprogram types
12696 then
12697 -- It is valid to convert from one RAS type to another provided
12698 -- that their specification statically match.
12700 -- Note: at this point, remote access to subprogram types have been
12701 -- expanded to their E_Record_Type representation, and we need to
12702 -- go back to the original access type definition using the
12703 -- Corresponding_Remote_Type attribute in order to check that the
12704 -- designated profiles match.
12709 Check_Subtype_Conformant
12712 Old_Id =>
12714 Err_Loc =>
12715 N);
12718 -- If it was legal in the generic, it's legal in the instance
12723 -- If both are tagged types, check legality of view conversions
12726 and then
12728 then
12731 -- Types derived from the same root type are convertible
12736 -- In an instance or an inlined body, there may be inconsistent views of
12737 -- the same type, or of types derived from a common root.
12740 and then
12743 then
12746 -- Special check for common access type error case
12750 then
12752 Conversion_Error_NE -- CODEFIX
12756 -- Here we have a real conversion error
12758 else
12759 Conversion_Error_NE