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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S E M _ R E S --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2017, 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 ------------------------------------------------------------------------------
86 -----------------------
87 -- Local Subprograms --
88 -----------------------
90 -- Second pass (top-down) type checking and overload resolution procedures
91 -- Typ is the type required by context. These procedures propagate the
92 -- type information recursively to the descendants of N. If the node is not
93 -- overloaded, its Etype is established in the first pass. If overloaded,
94 -- the Resolve routines set the correct type. For arithmetic operators, the
95 -- Etype is the base type of the context.
97 -- Note that Resolve_Attribute is separated off in Sem_Attr
100 -- Enforce the restrictions on the use of discriminants when constraining
101 -- a component of a discriminated type (record or concurrent type).
104 -- Given a node for an operator associated with type T, check that the
105 -- operator is visible. Operators all of whose operands are universal must
106 -- be checked for visibility during resolution because their type is not
107 -- determinable based on their operands.
109 procedure Check_Fully_Declared_Prefix
112 -- Check that the type of the prefix of a dereference is not incomplete
115 -- Given a call node, N, which is known to occur immediately within the
116 -- subprogram being called, determines whether it is a detectable case of
117 -- an infinite recursion, and if so, outputs appropriate messages. Returns
118 -- True if an infinite recursion is detected, and False otherwise.
121 -- If the type of the object being initialized uses the secondary stack
122 -- directly or indirectly, create a transient scope for the call to the
123 -- init proc. This is because we do not create transient scopes for the
124 -- initialization of individual components within the init proc itself.
125 -- Could be optimized away perhaps?
128 -- N is the node for a logical operator. If the operator is predefined, and
129 -- the root type of the operands is Standard.Boolean, then a check is made
130 -- for restriction No_Direct_Boolean_Operators. This procedure also handles
131 -- the style check for Style_Check_Boolean_And_Or.
134 -- N is either an indexed component or a selected component. This function
135 -- returns true if the prefix refers to an object that has an address
136 -- clause (the case in which we may want to issue a warning).
139 -- Determine whether E is an access type declared by an access declaration,
140 -- and not an (anonymous) allocator type.
143 -- Utility to check whether the entity for an operator is a predefined
144 -- operator, in which case the expression is left as an operator in the
145 -- tree (else it is rewritten into a call). An instance of an intrinsic
146 -- conversion operation may be given an operator name, but is not treated
147 -- like an operator. Note that an operator that is an imported back-end
148 -- builtin has convention Intrinsic, but is expected to be rewritten into
149 -- a call, so such an operator is not treated as predefined by this
150 -- predicate.
153 -- If a default expression in entry call N depends on the discriminants
154 -- of the task, it must be replaced with a reference to the discriminant
155 -- of the task being called.
157 procedure Resolve_Op_Concat_Arg
162 -- Internal procedure for Resolve_Op_Concat to resolve one operand of
163 -- concatenation operator. The operand is either of the array type or of
164 -- the component type. If the operand is an aggregate, and the component
165 -- type is composite, this is ambiguous if component type has aggregates.
168 -- Does the first part of the work of Resolve_Op_Concat
171 -- Does the "rest" of the work of Resolve_Op_Concat, after the left operand
172 -- 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
1900 --------------------
1901 -- Patch_Up_Value --
1902 --------------------
1905 begin
1922 then
1927 Char_Literal_Value =>
1943 -------------------------------
1944 -- Report_Ambiguous_Argument --
1945 -------------------------------
1952 begin
1956 then
1959 -- Could use comments on what is going on here???
1967 else
1976 -----------------------
1977 -- Resolution_Failed --
1978 -----------------------
1981 begin
1984 -- Set the type to the desired one to minimize cascaded errors. Note
1985 -- that this is an approximation and does not work in all cases.
1992 -- The caller will return without calling the expander, so we need
1993 -- to set the analyzed flag. Note that it is fine to set Analyzed
1994 -- to True even if we are in the middle of a shallow analysis,
1995 -- (see the spec of sem for more details) since this is an error
1996 -- situation anyway, and there is no point in repeating the
1997 -- analysis later (indeed it won't work to repeat it later, since
1998 -- we haven't got a clear resolution of which entity is being
1999 -- referenced.)
2005 -- Start of processing for Resolve
2007 begin
2012 -- Access attribute on remote subprogram cannot be used for a non-remote
2013 -- access-to-subprogram type.
2017 Name_Unrestricted_Access,
2018 Name_Unchecked_Access)
2024 then
2025 Error_Msg_N
2031 -- If the context is a Remote_Access_To_Subprogram, access attributes
2032 -- must be resolved with the corresponding fat pointer. There is no need
2033 -- to check for the attribute name since the return type of an
2034 -- attribute is never a remote type.
2039 then
2040 declare
2048 begin
2049 -- Check that Typ is a remote access-to-subprogram type
2053 -- Prefix (N) must statically denote a remote subprogram
2054 -- declared in a package specification.
2058 Attr = Attribute_Unrestricted_Access
2059 then
2074 or else
2076 then
2078 Error_Msg_N
2080 N);
2083 -- If we are generating code in distributed mode, perform
2084 -- semantic checks against corresponding remote entities.
2086 if Expander_Active
2088 then
2089 Check_Subtype_Conformant
2091 Old_Id => Designated_Type
2117 then
2122 -- Return if already analyzed
2129 -- Any case of Any_Type as the Etype value means that we had a
2130 -- previous error.
2139 -- The resolution of an Expression_With_Actions is determined by
2140 -- its Expression.
2148 -- If not overloaded, then we know the type, and all that needs doing
2149 -- is to check that this type is compatible with the context.
2155 -- In the overloaded case, we must select the interpretation that
2156 -- is compatible with the context (i.e. the type passed to Resolve)
2158 else
2159 -- Loop through possible interpretations
2168 -- We are only interested in interpretations that are compatible
2169 -- with the expected type, any other interpretations are ignored.
2174 Write_Eol;
2177 else
2178 -- Skip the current interpretation if it is disabled by an
2179 -- abstract operator. This action is performed only when the
2180 -- type against which we are resolving is the same as the
2181 -- type of the interpretation.
2188 then
2196 -- First matching interpretation
2204 -- Matching interpretation that is not the first, maybe an
2205 -- error, but there are some cases where preference rules are
2206 -- used to choose between the two possibilities. These and
2207 -- some more obscure cases are handled in Disambiguate.
2209 else
2210 -- If the current statement is part of a predefined library
2211 -- unit, then all interpretations which come from user level
2212 -- packages should not be considered. Check previous and
2213 -- current one.
2221 -- Previous interpretation must be discarded
2231 -- Otherwise apply further disambiguation steps
2236 -- Disambiguation has succeeded. Skip the remaining
2237 -- interpretations.
2247 else
2248 -- Before we issue an ambiguity complaint, check for the
2249 -- case of a subprogram call where at least one of the
2250 -- arguments is Any_Type, and if so suppress the message,
2251 -- since it is a cascaded error. This can also happen for
2252 -- a generalized indexing operation.
2257 then
2258 declare
2262 begin
2278 Write_Eol;
2291 then
2296 then
2300 -- Not that special case, so issue message using the flag
2301 -- Ambiguous to control printing of the header message
2302 -- only at the start of an ambiguous set.
2307 then
2308 Error_Msg_N
2311 else
2312 Error_Msg_NE -- CODEFIX
2320 Error_Msg_N
2322 else
2323 Error_Msg_N -- CODEFIX
2329 then
2330 Report_Ambiguous_Argument;
2336 -- By default, the error message refers to the candidate
2337 -- interpretation. But if it is a predefined operator, it
2338 -- is implicitly declared at the declaration of the type
2339 -- of the operand. Recover the sloc of that declaration
2340 -- for the error message.
2346 Standard_Standard
2347 then
2352 then
2360 Standard_Standard
2361 then
2366 then
2370 -- If this is an indirect call, use the subprogram_type
2371 -- in the message, to have a meaningful location. Also
2372 -- indicate if this is an inherited operation, created
2373 -- by a type declaration.
2378 then
2380 Error_Msg_Sloc :=
2382 else
2389 then
2390 -- Special-case the message for universal_fixed
2391 -- operators, which are not declared with the type
2392 -- of the operand, but appear forever in Standard.
2396 then
2397 Error_Msg_N
2400 else
2401 Error_Msg_N
2405 elsif
2407 then
2408 Error_Msg_N
2410 else
2411 Error_Msg_N -- CODEFIX
2418 -- We have a matching interpretation, Expr_Type is the type
2419 -- from this interpretation, and Seen is the entity.
2421 -- For an operator, just set the entity name. The type will be
2422 -- set by the specific operator resolution routine.
2437 -- AI05-0139-2: Expression is overloaded because type has
2438 -- implicit dereference. If type matches context, no implicit
2439 -- dereference is involved.
2450 then
2451 -- If the node is a general indexing, the dereference is
2452 -- is inserted when resolving the rewritten form, else
2453 -- insert it now.
2457 then
2461 -- For an explicit dereference, attribute reference, range,
2462 -- short-circuit form (which is not an operator node), or call
2463 -- with a name that is an explicit dereference, there is
2464 -- nothing to be done at this point.
2467 N_And_Then,
2468 N_Explicit_Dereference,
2469 N_Identifier,
2470 N_Indexed_Component,
2471 N_Or_Else,
2472 N_Range,
2473 N_Selected_Component,
2474 N_Slice)
2476 then
2479 -- For procedure or function calls, set the type of the name,
2480 -- and also the entity pointer for the prefix.
2484 then
2491 then
2496 -- For all other cases, just set the type of the Name
2498 else
2506 -- Move to next interpretation
2514 -- At this stage Found indicates whether or not an acceptable
2515 -- interpretation exists. If not, then we have an error, except that if
2516 -- the context is Any_Type as a result of some other error, then we
2517 -- suppress the error report.
2522 -- If type we are looking for is Void, then this is the procedure
2523 -- call case, and the error is simply that what we gave is not a
2524 -- procedure name (we think of procedure calls as expressions with
2525 -- types internally, but the user doesn't think of them this way).
2529 -- Special case message if function used as a procedure
2534 then
2535 Error_Msg_NE
2539 -- Otherwise give general message (not clear what cases this
2540 -- covers, but no harm in providing for them).
2542 else
2548 -- Otherwise we do have a subexpression with the wrong type
2550 -- Check for the case of an allocator which uses an access type
2551 -- instead of the designated type. This is a common error and we
2552 -- specialize the message, posting an error on the operand of the
2553 -- allocator, complaining that we expected the designated type of
2554 -- the allocator.
2560 then
2564 -- Check for view mismatch on Null in instances, for which the
2565 -- view-swapping mechanism has no identifier.
2571 then
2576 -- Check for an aggregate. Sometimes we can get bogus aggregates
2577 -- from misuse of parentheses, and we are about to complain about
2578 -- the aggregate without even looking inside it.
2580 -- Instead, if we have an aggregate of type Any_Composite, then
2581 -- analyze and resolve the component fields, and then only issue
2582 -- another message if we get no errors doing this (otherwise
2583 -- assume that the errors in the aggregate caused the problem).
2587 then
2588 -- Disable expansion in any case. If there is a type mismatch
2589 -- it may be fatal to try to expand the aggregate. The flag
2590 -- would otherwise be set to false when the error is posted.
2594 declare
2596 -- Check one aggregate, and set Found to True if we have a
2597 -- definite error in any of its elements
2600 -- Check one element of aggregate and set Found to True if
2601 -- we definitely have an error in the element.
2603 ----------------
2604 -- Check_Aggr --
2605 ----------------
2610 begin
2623 -- If this is a default-initialized component, then
2624 -- there is nothing to check. The box will be
2625 -- replaced by the appropriate call during late
2626 -- expansion.
2630 then
2639 ----------------
2640 -- Check_Elmt --
2641 ----------------
2644 begin
2645 -- If we have a nested aggregate, go inside it (to
2646 -- attempt a naked analyze-resolve of the aggregate can
2647 -- cause undesirable cascaded errors). Do not resolve
2648 -- expression if it needs a type from context, as for
2649 -- integer * fixed expression.
2654 else
2659 then
2669 begin
2674 -- Looks like we have a type error, but check for special case
2675 -- of Address wanted, integer found, with the configuration pragma
2676 -- Allow_Integer_Address active. If we have this case, introduce
2677 -- an unchecked conversion to allow the integer expression to be
2678 -- treated as an Address. The reverse case of integer wanted,
2679 -- Address found, is treated in an analogous manner.
2686 -- Under relaxed RM semantics silently replace occurrences of null
2687 -- by System.Address_Null.
2695 -- That special Allow_Integer_Address check did not apply, so we
2696 -- have a real type error. If an error message was issued already,
2697 -- Found got reset to True, so if it's still False, issue standard
2698 -- Wrong_Type message.
2702 declare
2705 begin
2711 -- Protected operation: retrieve operation name
2715 else
2720 Error_Msg_NE
2726 declare
2730 begin
2737 Error_Msg_NE
2743 else
2747 else
2753 Resolution_Failed;
2756 -- Test if we have more than one interpretation for the context
2759 Resolution_Failed;
2762 -- Only one intepretation
2764 else
2765 -- In Ada 2005, if we have something like "X : T := 2 + 2;", where
2766 -- the "+" on T is abstract, and the operands are of universal type,
2767 -- the above code will have (incorrectly) resolved the "+" to the
2768 -- universal one in Standard. Therefore check for this case and give
2769 -- an error. We can't do this earlier, because it would cause legal
2770 -- cases to get errors (when some other type has an abstract "+").
2776 then
2781 then
2782 Error_Msg_NE
2791 -- Here we have an acceptable interpretation for the context
2793 -- Propagate type information and normalize tree for various
2794 -- predefined operations. If the context only imposes a class of
2795 -- types, rather than a specific type, propagate the actual type
2796 -- downward.
2802 Typ = Any_Discrete
2803 then
2806 -- Any_Fixed is legal in a real context only if a specific fixed-
2807 -- point type is imposed. If Norman Cohen can be confused by this,
2808 -- it deserves a separate message.
2812 then
2819 -- A user-defined operator is transformed into a function call at
2820 -- this point, so that further processing knows that operators are
2821 -- really operators (i.e. are predefined operators). User-defined
2822 -- operators that are intrinsic are just renamings of the predefined
2823 -- ones, and need not be turned into calls either, but if they rename
2824 -- a different operator, we must transform the node accordingly.
2825 -- Instantiations of Unchecked_Conversion are intrinsic but are
2826 -- treated as functions, even if given an operator designator.
2831 then
2836 and then
2838 N_Subprogram_Renaming_Declaration
2839 then
2842 -- If the node is rewritten, it will be fully resolved in
2843 -- Rewrite_Renamed_Operator.
2852 when N_Aggregate =>
2853 Resolve_Aggregate (N, Ctx_Type);
2855 when N_Allocator =>
2856 Resolve_Allocator (N, Ctx_Type);
2858 when N_Short_Circuit =>
2859 Resolve_Short_Circuit (N, Ctx_Type);
2861 when N_Attribute_Reference =>
2862 Resolve_Attribute (N, Ctx_Type);
2864 when N_Case_Expression =>
2865 Resolve_Case_Expression (N, Ctx_Type);
2867 when N_Character_Literal =>
2868 Resolve_Character_Literal (N, Ctx_Type);
2870 when N_Delta_Aggregate =>
2871 Resolve_Delta_Aggregate (N, Ctx_Type);
2873 when N_Expanded_Name =>
2874 Resolve_Entity_Name (N, Ctx_Type);
2876 when N_Explicit_Dereference =>
2877 Resolve_Explicit_Dereference (N, Ctx_Type);
2879 when N_Expression_With_Actions =>
2880 Resolve_Expression_With_Actions (N, Ctx_Type);
2882 when N_Extension_Aggregate =>
2883 Resolve_Extension_Aggregate (N, Ctx_Type);
2885 when N_Function_Call =>
2886 Resolve_Call (N, Ctx_Type);
2888 when N_Identifier =>
2889 Resolve_Entity_Name (N, Ctx_Type);
2891 when N_If_Expression =>
2892 Resolve_If_Expression (N, Ctx_Type);
2894 when N_Indexed_Component =>
2895 Resolve_Indexed_Component (N, Ctx_Type);
2897 when N_Integer_Literal =>
2898 Resolve_Integer_Literal (N, Ctx_Type);
2900 when N_Membership_Test =>
2901 Resolve_Membership_Op (N, Ctx_Type);
2903 when N_Null =>
2904 Resolve_Null (N, Ctx_Type);
2906 when N_Op_And
2907 | N_Op_Or
2908 | N_Op_Xor
2909 =>
2910 Resolve_Logical_Op (N, Ctx_Type);
2912 when N_Op_Eq
2913 | N_Op_Ne
2914 =>
2915 Resolve_Equality_Op (N, Ctx_Type);
2917 when N_Op_Ge
2918 | N_Op_Gt
2919 | N_Op_Le
2920 | N_Op_Lt
2921 =>
2922 Resolve_Comparison_Op (N, Ctx_Type);
2924 when N_Op_Not =>
2925 Resolve_Op_Not (N, Ctx_Type);
2927 when N_Op_Add
2928 | N_Op_Divide
2929 | N_Op_Mod
2930 | N_Op_Multiply
2931 | N_Op_Rem
2932 | N_Op_Subtract
2933 =>
2934 Resolve_Arithmetic_Op (N, Ctx_Type);
2936 when N_Op_Concat =>
2937 Resolve_Op_Concat (N, Ctx_Type);
2939 when N_Op_Expon =>
2940 Resolve_Op_Expon (N, Ctx_Type);
2942 when N_Op_Abs
2943 | N_Op_Minus
2944 | N_Op_Plus
2945 =>
2946 Resolve_Unary_Op (N, Ctx_Type);
2948 when N_Op_Shift =>
2949 Resolve_Shift (N, Ctx_Type);
2951 when N_Procedure_Call_Statement =>
2952 Resolve_Call (N, Ctx_Type);
2954 when N_Operator_Symbol =>
2955 Resolve_Operator_Symbol (N, Ctx_Type);
2957 when N_Qualified_Expression =>
2958 Resolve_Qualified_Expression (N, Ctx_Type);
2960 -- Why is the following null, needs a comment ???
2962 when N_Quantified_Expression =>
2963 null;
2965 when N_Raise_Expression =>
2966 Resolve_Raise_Expression (N, Ctx_Type);
2968 when N_Raise_xxx_Error =>
2969 Set_Etype (N, Ctx_Type);
2971 when N_Range =>
2972 Resolve_Range (N, Ctx_Type);
2974 when N_Real_Literal =>
2975 Resolve_Real_Literal (N, Ctx_Type);
2977 when N_Reference =>
2978 Resolve_Reference (N, Ctx_Type);
2980 when N_Selected_Component =>
2981 Resolve_Selected_Component (N, Ctx_Type);
2983 when N_Slice =>
2984 Resolve_Slice (N, Ctx_Type);
2986 when N_String_Literal =>
2987 Resolve_String_Literal (N, Ctx_Type);
2989 when N_Target_Name =>
2990 Resolve_Target_Name (N, Ctx_Type);
2992 when N_Type_Conversion =>
2993 Resolve_Type_Conversion (N, Ctx_Type);
2995 when N_Unchecked_Expression =>
2996 Resolve_Unchecked_Expression (N, Ctx_Type);
2998 when N_Unchecked_Type_Conversion =>
2999 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
3000 end case;
3002 -- Ada 2012 (AI05-0149): Apply an (implicit) conversion to an
3003 -- expression of an anonymous access type that occurs in the context
3004 -- of a named general access type, except when the expression is that
3005 -- of a membership test. This ensures proper legality checking in
3006 -- terms of allowed conversions (expressions that would be illegal to
3007 -- convert implicitly are allowed in membership tests).
3009 if Ada_Version >= Ada_2012
3010 and then Ekind (Ctx_Type) = E_General_Access_Type
3011 and then Ekind (Etype (N)) = E_Anonymous_Access_Type
3012 and then Nkind (Parent (N)) not in N_Membership_Test
3013 then
3014 Rewrite (N, Convert_To (Ctx_Type, Relocate_Node (N)));
3015 Analyze_And_Resolve (N, Ctx_Type);
3016 end if;
3018 -- If the subexpression was replaced by a non-subexpression, then
3019 -- all we do is to expand it. The only legitimate case we know of
3020 -- is converting procedure call statement to entry call statements,
3021 -- but there may be others, so we are making this test general.
3023 if Nkind (N) not in N_Subexpr then
3024 Debug_A_Exit ("resolving ", N, " (done)");
3025 Expand (N);
3026 return;
3027 end if;
3029 -- The expression is definitely NOT overloaded at this point, so
3030 -- we reset the Is_Overloaded flag to avoid any confusion when
3031 -- reanalyzing the node.
3033 Set_Is_Overloaded (N, False);
3035 -- Freeze expression type, entity if it is a name, and designated
3036 -- type if it is an allocator (RM 13.14(10,11,13)).
3038 -- Now that the resolution of the type of the node is complete, and
3039 -- we did not detect an error, we can expand this node. We skip the
3040 -- expand call if we are in a default expression, see section
3041 -- "Handling of Default Expressions" in Sem spec.
3043 Debug_A_Exit ("resolving ", N, " (done)");
3045 -- We unconditionally freeze the expression, even if we are in
3046 -- default expression mode (the Freeze_Expression routine tests this
3047 -- flag and only freezes static types if it is set).
3049 -- Ada 2012 (AI05-177): The declaration of an expression function
3050 -- does not cause freezing, but we never reach here in that case.
3051 -- Here we are resolving the corresponding expanded body, so we do
3052 -- need to perform normal freezing.
3054 Freeze_Expression (N);
3056 -- Now we can do the expansion
3058 Expand (N);
3059 end if;
3060 end Resolve;
3062 -------------
3063 -- Resolve --
3064 -------------
3066 -- Version with check(s) suppressed
3068 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
3069 begin
3070 if Suppress = All_Checks then
3071 declare
3072 Sva : constant Suppress_Array := Scope_Suppress.Suppress;
3073 begin
3074 Scope_Suppress.Suppress := (others => True);
3075 Resolve (N, Typ);
3076 Scope_Suppress.Suppress := Sva;
3077 end;
3079 else
3080 declare
3081 Svg : constant Boolean := Scope_Suppress.Suppress (Suppress);
3082 begin
3083 Scope_Suppress.Suppress (Suppress) := True;
3084 Resolve (N, Typ);
3085 Scope_Suppress.Suppress (Suppress) := Svg;
3086 end;
3087 end if;
3088 end Resolve;
3090 -------------
3091 -- Resolve --
3092 -------------
3094 -- Version with implicit type
3096 procedure Resolve (N : Node_Id) is
3097 begin
3098 Resolve (N, Etype (N));
3099 end Resolve;
3101 ---------------------
3102 -- Resolve_Actuals --
3103 ---------------------
3105 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
3106 Loc : constant Source_Ptr := Sloc (N);
3107 A : Node_Id;
3108 A_Id : Entity_Id;
3109 A_Typ : Entity_Id;
3110 F : Entity_Id;
3111 F_Typ : Entity_Id;
3112 Prev : Node_Id := Empty;
3113 Orig_A : Node_Id;
3114 Real_F : Entity_Id;
3116 Real_Subp : Entity_Id;
3117 -- If the subprogram being called is an inherited operation for
3118 -- a formal derived type in an instance, Real_Subp is the subprogram
3119 -- that will be called. It may have different formal names than the
3120 -- operation of the formal in the generic, so after actual is resolved
3121 -- the name of the actual in a named association must carry the name
3122 -- of the actual of the subprogram being called.
3124 procedure Check_Aliased_Parameter;
3125 -- Check rules on aliased parameters and related accessibility rules
3126 -- in (RM 3.10.2 (10.2-10.4)).
3128 procedure Check_Argument_Order;
3129 -- Performs a check for the case where the actuals are all simple
3130 -- identifiers that correspond to the formal names, but in the wrong
3131 -- order, which is considered suspicious and cause for a warning.
3133 procedure Check_Prefixed_Call;
3134 -- If the original node is an overloaded call in prefix notation,
3136 -- Try_Object_Operation has already verified that there is a valid
3137 -- interpretation, but the form of the actual can only be determined
3138 -- once the primitive operation is identified.
3141 -- Emit an error concerning the illegal usage of an effectively volatile
3142 -- object in interfering context (SPARK RM 7.13(12)).
3145 -- If the actual is missing in a call, insert in the actuals list
3146 -- an instance of the default expression. The insertion is always
3147 -- a named association.
3149 procedure Property_Error
3153 -- Emit an error concerning variable Var with entity Var_Id that has
3154 -- enabled property Prop_Nam when it acts as an actual parameter in a
3155 -- call and the corresponding formal parameter is of mode IN.
3158 -- Check whether T1 and T2, or their full views, are derived from a
3159 -- common type. Used to enforce the restrictions on array conversions
3160 -- of AI95-00246.
3163 -- Predicate to determine whether an actual that is a concatenation
3164 -- will be evaluated statically and does not need a transient scope.
3165 -- This must be determined before the actual is resolved and expanded
3166 -- because if needed the transient scope must be introduced earlier.
3168 -----------------------------
3169 -- Check_Aliased_Parameter --
3170 -----------------------------
3175 begin
3183 else
3190 -- In a generic body assume the worst for generic formals:
3191 -- they can have a constrained partial view (AI05-041).
3197 then
3200 else
3205 else
3217 then
3225 then
3226 Error_Msg_N
3232 --------------------------
3233 -- Check_Argument_Order --
3234 --------------------------
3237 begin
3238 -- Nothing to do if no parameters, or original node is neither a
3239 -- function call nor a procedure call statement (happens in the
3240 -- operator-transformed-to-function call case), or the call does
3241 -- not come from source, or this warning is off.
3243 if not Warn_On_Parameter_Order
3247 then
3251 declare
3254 begin
3255 -- Nothing to do if only one parameter
3261 -- Here if at least two arguments
3263 declare
3269 -- Set True if an out of order case is found
3271 begin
3272 -- Collect identifier names of actuals, fail if any actual is
3273 -- not a simple identifier, and record max length of name.
3279 else
3285 -- If we got this far, all actuals are identifiers and the list
3286 -- of their names is stored in the Actuals array.
3291 -- If we ran out of formals, that's odd, probably an error
3292 -- which will be detected elsewhere, but abandon the search.
3298 -- If name matches and is in order OK
3303 else
3304 -- If no match, see if it is elsewhere in list and if so
3305 -- flag potential wrong order if type is compatible.
3309 and then
3311 then
3317 -- No match
3325 -- If Formals left over, also probably an error, skip warning
3331 -- Here we give the warning if something was out of order
3334 Error_Msg_N
3341 -------------------------
3342 -- Check_Prefixed_Call --
3343 -------------------------
3352 begin
3353 -- Check whether the call is a prefixed call, with or without
3354 -- additional actuals.
3357 or else
3363 then
3366 then
3367 -- Introduce dereference on object in prefix
3369 New_A :=
3377 then
3378 -- Introduce an implicit 'Access in prefix
3381 Error_Msg_NE
3397 ---------------------------------------
3398 -- Flag_Effectively_Volatile_Objects --
3399 ---------------------------------------
3403 -- Determine whether arbitrary node N denotes an effectively volatile
3404 -- object and if it does, emit an error.
3406 -----------------
3407 -- Flag_Object --
3408 -----------------
3413 begin
3414 -- Do not consider nested function calls because they have already
3415 -- been processed during their own resolution.
3427 then
3428 Error_Msg_N
3440 -- Start of processing for Flag_Effectively_Volatile_Objects
3442 begin
3446 --------------------
3447 -- Insert_Default --
3448 --------------------
3454 begin
3455 -- Missing argument in call, nothing to insert
3460 else
3461 -- Note that we do a full New_Copy_Tree, so that any associated
3462 -- Itypes are properly copied. This may not be needed any more,
3463 -- but it does no harm as a safety measure. Defaults of a generic
3464 -- formal may be out of bounds of the corresponding actual (see
3465 -- cc1311b) and an additional check may be required.
3467 Actval :=
3468 New_Copy_Tree
3473 -- Propagate dimension information, if any.
3479 then
3485 then
3488 then
3489 -- If default is a real literal, do not introduce a
3490 -- conversion whose effect may depend on the run-time
3491 -- size of universal real.
3495 else
3506 -- Resolve aggregates with their base type, to avoid scope
3507 -- anomalies: the subtype was first built in the subprogram
3508 -- declaration, and the current call may be nested.
3512 else
3516 else
3519 -- See note above concerning aggregates
3523 then
3526 -- Resolve entities with their own type, which may differ from
3527 -- the type of a reference in a generic context (the view
3528 -- swapping mechanism did not anticipate the re-analysis of
3529 -- default values in calls).
3534 else
3539 -- If default is a tag indeterminate function call, propagate tag
3540 -- to obtain proper dispatching.
3544 then
3549 -- If the default expression raises constraint error, then just
3550 -- silently replace it with an N_Raise_Constraint_Error node, since
3551 -- we already gave the warning on the subprogram spec. If node is
3552 -- already a Raise_Constraint_Error leave as is, to prevent loops in
3553 -- the warnings removal machinery.
3557 then
3565 Assoc :=
3570 -- Case of insertion is first named actual
3574 then
3581 else
3585 else
3589 -- Case of insertion is not first named actual
3591 else
3592 Set_Next_Named_Actual
3604 --------------------
3605 -- Property_Error --
3606 --------------------
3608 procedure Property_Error
3612 is
3613 begin
3615 Error_Msg_NE
3621 -------------------
3622 -- Same_Ancestor --
3623 -------------------
3629 begin
3632 then
3638 then
3645 --------------------------
3646 -- Static_Concatenation --
3647 --------------------------
3650 begin
3657 -- Concatenation is static when both operands are static and
3658 -- the concatenation operator is a predefined one.
3661 and then
3663 and then
3668 declare
3670 begin
3673 and then
3677 else
3683 -- Start of processing for Resolve_Actuals
3685 begin
3686 Check_Argument_Order;
3690 and then In_Instance
3693 then
3695 else
3700 Check_Prefixed_Call;
3714 -- If we have an error in any actual or formal, indicated by a type
3715 -- of Any_Type, then abandon resolution attempt, and set result type
3716 -- to Any_Type. Skip this if the actual is a Raise_Expression, whose
3717 -- type is imposed from context.
3721 then
3728 -- Case where actual is present
3730 -- If the actual is an entity, generate a reference to it now. We
3731 -- do this before the actual is resolved, because a formal of some
3732 -- protected subprogram, or a task discriminant, will be rewritten
3733 -- during expansion, and the source entity reference may be lost.
3738 then
3744 then
3751 -- RM 6.4.1(12): For an out parameter that is passed by
3752 -- copy, the formal parameter object is created, and:
3754 -- * For an access type, the formal parameter is initialized
3755 -- from the value of the actual, without checking that the
3756 -- value satisfies any constraint, any predicate, or any
3757 -- exclusion of the null value.
3759 -- * For a scalar type that has the Default_Value aspect
3760 -- specified, the formal parameter is initialized from the
3761 -- value of the actual, without checking that the value
3762 -- satisfies any constraint or any predicate.
3763 -- I do not understand why this case is included??? this is
3764 -- not a case where an OUT parameter is treated as IN OUT.
3766 -- * For a composite type with discriminants or that has
3767 -- implicit initial values for any subcomponents, the
3768 -- behavior is as for an in out parameter passed by copy.
3770 -- Hence for these cases we generate the read reference now
3771 -- (the write reference will be generated later by
3772 -- Note_Possible_Modification).
3775 and then
3777 or else
3779 and then
3781 or else
3784 or else Is_Partially_Initialized_Type
3786 then
3796 then
3797 -- If style checking mode on, check match of formal name
3805 -- If the formal is Out or In_Out, do not resolve and expand the
3806 -- conversion, because it is subsequently expanded into explicit
3807 -- temporaries and assignments. However, the object of the
3808 -- conversion can be resolved. An exception is the case of tagged
3809 -- type conversion with a class-wide actual. In that case we want
3810 -- the tag check to occur and no temporary will be needed (no
3811 -- representation change can occur) and the parameter is passed by
3812 -- reference, so we go ahead and resolve the type conversion.
3813 -- Another exception is the case of reference to component or
3814 -- subcomponent of a bit-packed array, in which case we want to
3815 -- defer expansion to the point the in and out assignments are
3816 -- performed.
3821 then
3824 then
3825 -- In a view conversion, the conversion must be legal in
3826 -- both directions, and thus both component types must be
3827 -- aliased, or neither (4.6 (8)).
3829 -- The extra rule in 4.6 (24.9.2) seems unduly restrictive:
3830 -- the privacy requirement should not apply to generic
3831 -- types, and should be checked in an instance. ARG query
3832 -- is in order ???
3836 then
3837 Error_Msg_N
3841 -- Comment here??? what set of cases???
3843 elsif
3845 then
3846 -- Check view conv between unrelated by ref array types
3850 then
3851 Error_Msg_N
3855 -- In Ada 2005 mode, check view conversion component
3856 -- type cannot be private, tagged, or volatile. Note
3857 -- that we only apply this to source conversions. The
3858 -- generated code can contain conversions which are
3859 -- not subject to this test, and we cannot extract the
3860 -- component type in such cases since it is not present.
3864 then
3865 declare
3867 Component_Type
3869 begin
3874 then
3875 Error_Msg_N
3886 -- Resolve expression if conversion is all OK
3891 then
3895 -- If the actual is a function call that returns a limited
3896 -- unconstrained object that needs finalization, create a
3897 -- transient scope for it, so that it can receive the proper
3898 -- finalization list.
3903 and then Expander_Active
3905 then
3909 -- A small optimization: if one of the actuals is a concatenation
3910 -- create a block around a procedure call to recover stack space.
3911 -- This alleviates stack usage when several procedure calls in
3912 -- the same statement list use concatenation. We do not perform
3913 -- this wrapping for code statements, where the argument is a
3914 -- static string, and we want to preserve warnings involving
3915 -- sequences of such statements.
3919 and then Expander_Active
3920 and then
3924 then
3928 else
3932 and then
3935 then
3936 Error_Msg_N
3949 -- (Ada 2005: AI-251): If the actual is an allocator whose
3950 -- directly designated type is a class-wide interface, we build
3951 -- an anonymous access type to use it as the type of the
3952 -- allocator. Later, when the subprogram call is expanded, if
3953 -- the interface has a secondary dispatch table the expander
3954 -- will add a type conversion to force the correct displacement
3955 -- of the pointer.
3958 declare
3964 begin
3967 then
3970 Set_Directly_Designated_Type
3975 -- Ada 2005, AI-162:If the actual is an allocator, the
3976 -- innermost enclosing statement is the master of the
3977 -- created object. This needs to be done with expansion
3978 -- enabled only, otherwise the transient scope will not
3979 -- be removed in the expansion of the wrapped construct.
3982 and then Expander_Active
3983 then
3993 -- (Ada 2005): The call may be to a primitive operation of a
3994 -- tagged synchronized type, declared outside of the type. In
3995 -- this case the controlling actual must be converted to its
3996 -- corresponding record type, which is the formal type. The
3997 -- actual may be a subtype, either because of a constraint or
3998 -- because it is a generic actual, so use base type to locate
3999 -- concurrent type.
4006 then
4007 -- If the actual is overloaded, look for an interpretation
4008 -- that has a synchronized type.
4013 else
4014 declare
4018 begin
4023 then
4033 declare
4036 begin
4039 else
4043 -- Tagged synchronized type (case 1): the actual is a
4044 -- concurrent type.
4048 then
4050 Unchecked_Convert_To
4054 -- Tagged synchronized type (case 2): the formal is a
4055 -- concurrent type.
4058 and then Present
4063 then
4066 -- Common case
4068 else
4073 -- Not a synchronized operation
4075 else
4083 -- An actual cannot be an untagged formal incomplete type
4088 then
4089 Error_Msg_N
4095 N_Procedure_Call_Statement)
4096 then
4097 -- In formal mode, check that actual parameters matching
4098 -- formals of tagged types are objects (or ancestor type
4099 -- conversions of objects), not general expressions.
4106 declare
4111 begin
4113 Check_SPARK_05_Restriction
4116 -- In formal mode, the only view conversions are those
4117 -- involving ancestor conversion of an extended type.
4119 elsif not
4125 then
4126 if Ekind_In
4128 then
4129 Check_SPARK_05_Restriction
4132 else
4133 Check_SPARK_05_Restriction
4137 else
4142 else
4146 -- In formal mode, the only view conversions are those
4147 -- involving ancestor conversion of an extended type.
4151 then
4152 Check_SPARK_05_Restriction
4158 -- has warnings suppressed, then we reset Never_Set_In_Source for
4159 -- the calling entity. The reason for this is to catch cases like
4160 -- GNAT.Spitbol.Patterns.Vstring_Var where the called subprogram
4161 -- uses trickery to modify an IN parameter.
4168 then
4172 -- Perform error checks for IN and IN OUT parameters
4176 -- Check unset reference. For scalar parameters, it is clearly
4177 -- wrong to pass an uninitialized value as either an IN or
4178 -- IN-OUT parameter. For composites, it is also clearly an
4179 -- error to pass a completely uninitialized value as an IN
4180 -- parameter, but the case of IN OUT is trickier. We prefer
4181 -- not to give a warning here. For example, suppose there is
4182 -- a routine that sets some component of a record to False.
4183 -- It is perfectly reasonable to make this IN-OUT and allow
4184 -- either initialized or uninitialized records to be passed
4185 -- in this case.
4187 -- For partially initialized composite values, we also avoid
4188 -- warnings, since it is quite likely that we are passing a
4189 -- partially initialized value and only the initialized fields
4190 -- will in fact be read in the subprogram.
4195 then
4199 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
4200 -- actual to a nested call, since this constitutes a reading of
4201 -- the parameter, which is not allowed.
4206 then
4211 -- In -gnatd.q mode, forget that a given array is constant when
4212 -- it is passed as an IN parameter to a foreign-convention
4213 -- subprogram. This is in case the subprogram evilly modifies the
4214 -- object. Of course, correct code would use IN OUT.
4216 if Debug_Flag_Dot_Q
4222 then
4226 -- Case of OUT or IN OUT parameter
4230 -- For an Out parameter, check for useless assignment. Note
4231 -- that we can't set Last_Assignment this early, because we may
4232 -- kill current values in Resolve_Call, and that call would
4233 -- clobber the Last_Assignment field.
4235 -- Note: call Warn_On_Useless_Assignment before doing the check
4236 -- below for Is_OK_Variable_For_Out_Formal so that the setting
4237 -- of Referenced_As_LHS/Referenced_As_Out_Formal properly
4238 -- reflects the last assignment, not this one.
4245 then
4250 -- Validate the form of the actual. Note that the call to
4251 -- Is_OK_Variable_For_Out_Formal generates the required
4252 -- reference in this case.
4254 -- A call to an initialization procedure for an aggregate
4255 -- component may initialize a nested component of a constant
4256 -- designated object. In this context the object is variable.
4260 then
4266 then
4267 Error_Msg_N
4272 Error_Msg_N
4279 -- What's the following about???
4283 else
4284 Kill_All_Checks;
4293 -- Apply appropriate constraint/predicate checks for IN [OUT] case
4297 -- Apply predicate tests except in certain special cases. Note
4298 -- that it might be more consistent to apply these only when
4299 -- expansion is active (in Exp_Ch6.Expand_Actuals), as we do
4300 -- for the outbound predicate tests ??? In any case indicate
4301 -- the function being called, for better warnings if the call
4302 -- leads to an infinite recursion.
4308 -- Apply required constraint checks
4310 -- Gigi looks at the check flag and uses the appropriate types.
4311 -- For now since one flag is used there is an optimization
4312 -- which might not be done in the IN OUT case since Gigi does
4313 -- not do any analysis. More thought required about this ???
4315 -- In fact is this comment obsolete??? doesn't the expander now
4316 -- generate all these tests anyway???
4329 then
4332 -- For view conversions of a discriminated object, apply
4333 -- check to object itself, the conversion alreay has the
4334 -- proper type.
4338 then
4345 then
4351 then
4354 else
4358 -- Ada 2005 (AI-231): Note that the controlling parameter case
4359 -- already existed in Ada 95, which is partially checked
4360 -- elsewhere (see Checks), and we don't want the warning
4361 -- message to differ.
4366 then
4368 Apply_Compile_Time_Constraint_Error
4374 Apply_Compile_Time_Constraint_Error
4383 -- Checks for OUT parameters and IN OUT parameters
4387 -- If there is a type conversion, make sure the return value
4388 -- meets the constraints of the variable before the conversion.
4392 Apply_Scalar_Range_Check
4395 -- In addition, the returned value of the parameter must
4396 -- satisfy the bounds of the object type (see comment
4397 -- below).
4401 else
4402 Apply_Range_Check
4406 -- If no conversion, apply scalar range checks and length check
4407 -- based on the subtype of the actual (NOT that of the formal).
4408 -- This indicates that the check takes place on return from the
4409 -- call. During expansion the required constraint checks are
4410 -- inserted. In GNATprove mode, in the absence of expansion,
4411 -- the flag indicates that the returned value is valid.
4413 else
4419 then
4421 else
4426 -- Note: we do not apply the predicate checks for the case of
4427 -- OUT and IN OUT parameters. They are instead applied in the
4428 -- Expand_Actuals routine in Exp_Ch6.
4431 -- An actual associated with an access parameter is implicitly
4432 -- converted to the anonymous access type of the formal and must
4433 -- satisfy the legality checks for access conversions.
4437 Error_Msg_N
4441 -- If the actual is an access selected component of a variable,
4442 -- the call may modify its designated object. It is reasonable
4443 -- to treat this as a potential modification of the enclosing
4444 -- record, to prevent spurious warnings that it should be
4445 -- declared as a constant, because intuitively programmers
4446 -- regard the designated subcomponent as part of the record.
4451 then
4456 -- Check bad case of atomic/volatile argument (RM C.6(12))
4460 then
4463 then
4464 Error_Msg_NE
4470 then
4471 Error_Msg_NE
4477 -- Check that subprograms don't have improper controlling
4478 -- arguments (RM 3.9.2 (9)).
4480 -- A primitive operation may have an access parameter of an
4481 -- incomplete tagged type, but a dispatching call is illegal
4482 -- if the type is still incomplete.
4488 declare
4490 begin
4494 then
4495 Error_Msg_NE
4506 -- Apply legality rule 3.9.2 (9/1)
4511 and then not In_Instance
4512 then
4517 Error_Msg_NE
4521 -- Apply the checks described in 3.10.2(27): if the context is a
4522 -- specific access-to-object, the actual cannot be class-wide.
4523 -- Use base type to exclude access_to_subprogram cases.
4530 and then
4535 -- Disable these checks for call to imported C++ subprograms
4537 and then not
4541 then
4542 Error_Msg_N
4547 Error_Msg_NE
4552 Check_Aliased_Parameter;
4556 -- If it is a named association, treat the selector_name as a
4557 -- proper identifier, and mark the corresponding entity.
4561 -- Ignore reference in SPARK mode, as it refers to an entity not
4562 -- in scope at the point of reference, so the reference should
4563 -- be ignored for computing effects of subprograms.
4565 and then not GNATprove_Mode
4566 then
4567 -- If subprogram is overridden, use name of formal that
4568 -- is being called.
4574 else
4588 -- The following checks are only relevant when SPARK_Mode is on as
4589 -- they are not standard Ada legality rule. Internally generated
4590 -- temporaries are ignored.
4594 -- An effectively volatile object may act as an actual when the
4595 -- corresponding formal is of a non-scalar effectively volatile
4596 -- type (SPARK RM 7.1.3(11)).
4600 then
4603 -- An effectively volatile object may act as an actual in a
4604 -- call to an instance of Unchecked_Conversion.
4605 -- (SPARK RM 7.1.3(11)).
4610 -- The actual denotes an object
4613 Error_Msg_N
4617 -- Otherwise the actual denotes an expression. Inspect the
4618 -- expression and flag each effectively volatile object with
4619 -- enabled property Async_Writers or Effective_Reads as illegal
4620 -- because it apprears within an interfering context. Note that
4621 -- this is usually done in Resolve_Entity_Name, but when the
4622 -- effectively volatile object appears as an actual in a call,
4623 -- the call must be resolved first.
4625 else
4629 -- Detect an external variable with an enabled property that
4630 -- does not match the mode of the corresponding formal in a
4631 -- procedure call. Functions are not considered because they
4632 -- cannot have effectively volatile formal parameters in the
4633 -- first place.
4640 then
4653 -- A formal parameter of a specific tagged type whose related
4654 -- subprogram is subject to pragma Extensions_Visible with value
4655 -- "False" cannot act as an actual in a subprogram with value
4656 -- "True" (SPARK RM 6.1.7(3)).
4660 Extensions_Visible_True
4661 then
4662 Error_Msg_N
4665 Error_Msg_NE
4669 -- The actual parameter of a Ghost subprogram whose formal is of
4670 -- mode IN OUT or OUT must be a Ghost variable (SPARK RM 6.9(12)).
4678 then
4679 Error_Msg_NE
4685 else
4692 -- Case where actual is not present
4694 else
4695 Insert_Default;
4706 -----------------------
4707 -- Resolve_Allocator --
4708 -----------------------
4720 procedure Check_Allocator_Discrim_Accessibility
4723 -- Check that accessibility level associated with an access discriminant
4724 -- initialized in an allocator by the expression Disc_Exp is not deeper
4725 -- than the level of the allocator type Alloc_Typ. An error message is
4726 -- issued if this condition is violated. Specialized checks are done for
4727 -- the cases of a constraint expression which is an access attribute or
4728 -- an access discriminant.
4731 -- If the allocator is an actual in a call, it is allowed to be class-
4732 -- wide when the context is not because it is a controlling actual.
4734 -------------------------------------------
4735 -- Check_Allocator_Discrim_Accessibility --
4736 -------------------------------------------
4738 procedure Check_Allocator_Discrim_Accessibility
4741 is
4742 begin
4745 then
4746 Error_Msg_N
4749 -- When the expression is an Access attribute the level of the prefix
4750 -- object must not be deeper than that of the allocator's type.
4754 Attribute_Access
4757 then
4758 Error_Msg_N
4760 Disc_Exp);
4762 -- When the expression is an access discriminant the check is against
4763 -- the level of the prefix object.
4769 then
4770 Error_Msg_N
4772 Disc_Exp);
4774 -- All other cases are legal
4776 else
4781 ----------------------------
4782 -- In_Dispatching_Context --
4783 ----------------------------
4788 begin
4794 -- Start of processing for Resolve_Allocator
4796 begin
4797 -- Replace general access with specific type
4807 -- For qualified expression, resolve the expression using the given
4808 -- subtype (nothing to do for type mark, subtype indication)
4813 and then not In_Dispatching_Context
4814 then
4815 Error_Msg_N
4823 -- Allocators generated by the build-in-place expansion mechanism
4824 -- are explicitly marked as coming from source but do not need to be
4825 -- checked for limited initialization. To exclude this case, ensure
4826 -- that the parent of the allocator is a source node.
4831 and then not In_Instance_Body
4832 then
4835 Error_Msg_N
4838 else
4839 Error_Msg_N
4847 -- A qualified expression requires an exact match of the type. Class-
4848 -- wide matching is not allowed.
4853 then
4857 -- Calls to build-in-place functions are not currently supported in
4858 -- allocators for access types associated with a simple storage pool.
4859 -- Supporting such allocators may require passing additional implicit
4860 -- parameters to build-in-place functions (or a significant revision
4861 -- of the current b-i-p implementation to unify the handling for
4862 -- multiple kinds of storage pools). ???
4866 then
4867 declare
4870 begin
4872 and then
4873 Present (Get_Rep_Pragma
4875 then
4876 Error_Msg_N
4883 -- A special accessibility check is needed for allocators that
4884 -- constrain access discriminants. The level of the type of the
4885 -- expression used to constrain an access discriminant cannot be
4886 -- deeper than the type of the allocator (in contrast to access
4887 -- parameters, where the level of the actual can be arbitrary).
4889 -- We can't use Valid_Conversion to perform this check because in
4890 -- general the type of the allocator is unrelated to the type of
4891 -- the access discriminant.
4895 then
4902 then
4905 -- Get the first component expression of the aggregate
4915 else
4919 else
4938 else
4943 else
4952 -- For a subtype mark or subtype indication, freeze the subtype
4954 else
4958 Error_Msg_N
4962 -- A special accessibility check is needed for allocators that
4963 -- constrain access discriminants. The level of the type of the
4964 -- expression used to constrain an access discriminant cannot be
4965 -- deeper than the type of the allocator (in contrast to access
4966 -- parameters, where the level of the actual can be arbitrary).
4967 -- We can't use Valid_Conversion to perform this check because
4968 -- in general the type of the allocator is unrelated to the type
4969 -- of the access discriminant.
4974 then
4984 else
4998 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
4999 -- check that the level of the type of the created object is not deeper
5000 -- than the level of the allocator's access type, since extensions can
5001 -- now occur at deeper levels than their ancestor types. This is a
5002 -- static accessibility level check; a run-time check is also needed in
5003 -- the case of an initialized allocator with a class-wide argument (see
5004 -- Expand_Allocator_Expression).
5008 then
5009 declare
5012 begin
5017 else
5023 then
5026 Error_Msg_N
5035 -- Do not apply Ada 2005 accessibility checks on a class-wide
5036 -- allocator if the type given in the allocator is a formal
5037 -- type. A run-time check will be performed in the instance.
5047 -- Check for allocation from an empty storage pool
5052 -- If the context is an unchecked conversion, as may happen within an
5053 -- inlined subprogram, the allocator is being resolved with its own
5054 -- anonymous type. In that case, if the target type has a specific
5055 -- storage pool, it must be inherited explicitly by the allocator type.
5059 then
5060 Set_Associated_Storage_Pool
5068 -- Check that an allocator with task parts isn't for a nested access
5069 -- type when restriction No_Task_Hierarchy applies.
5073 then
5077 -- An illegal allocator may be rewritten as a raise Program_Error
5078 -- statement.
5082 -- An anonymous access discriminant is the definition of a
5083 -- coextension.
5087 N_Discriminant_Specification
5088 then
5089 declare
5093 begin
5096 -- Ada 2012 AI05-0052: If the designated type of the allocator
5097 -- is limited, then the allocator shall not be used to define
5098 -- the value of an access discriminant unless the discriminated
5099 -- type is immutably limited.
5104 then
5105 Error_Msg_N
5111 -- Avoid marking an allocator as a dynamic coextension if it is
5112 -- within a static construct.
5118 -- Cleanup for potential static coextensions
5120 else
5126 -- Report a simple error: if the designated object is a local task,
5127 -- its body has not been seen yet, and its activation will fail an
5128 -- elaboration check.
5135 then
5141 -- Ada 2012 (AI05-0111-3): Detect an attempt to allocate a task or a
5142 -- type with a task component on a subpool. This action must raise
5143 -- Program_Error at runtime.
5149 then
5161 ---------------------------
5162 -- Resolve_Arithmetic_Op --
5163 ---------------------------
5165 -- Used for resolving all arithmetic operators except exponentiation
5176 -- We do the resolution using the base type, because intermediate values
5177 -- in expressions always are of the base type, not a subtype of it.
5180 -- Returns True if N is in a context that expects "any real type"
5183 -- Return True iff given type is Integer or universal real/integer
5186 -- Choose type of integer literal in fixed-point operation to conform
5187 -- to available fixed-point type. T is the type of the other operand,
5188 -- which is needed to determine the expected type of N.
5191 -- Set operand type to T if universal
5193 -------------------------------
5194 -- Expected_Type_Is_Any_Real --
5195 -------------------------------
5198 begin
5199 -- N is the expression after "delta" in a fixed_point_definition;
5200 -- see RM-3.5.9(6):
5203 N_Decimal_Fixed_Point_Definition,
5205 -- N is one of the bounds in a real_range_specification;
5206 -- see RM-3.5.7(5):
5208 N_Real_Range_Specification,
5210 -- N is the expression of a delta_constraint;
5211 -- see RM-J.3(3):
5213 N_Delta_Constraint);
5216 -----------------------------
5217 -- Is_Integer_Or_Universal --
5218 -----------------------------
5225 begin
5231 else
5237 then
5248 ----------------------------
5249 -- Set_Mixed_Mode_Operand --
5250 ----------------------------
5256 begin
5259 -- A universal integer literal is resolved as standard integer
5260 -- except in the case of a fixed-point result, where we leave it
5261 -- as universal (to be handled by Exp_Fixd later on)
5265 else
5273 then
5274 -- A universal real can appear in a fixed-type context. We resolve
5275 -- the literal with that context, even though this might raise an
5276 -- exception prematurely (the other operand may be zero).
5283 then
5284 -- Integer arg in mixed-mode operation. Resolve with universal
5285 -- type, in case preference rule must be applied.
5291 then
5292 -- Not a mixed-mode operation, resolve with context
5298 -- N may itself be a mixed-mode operation, so use context type
5305 then
5306 -- Must be (fixed * fixed) operation, operand must have one
5307 -- compatible interpretation.
5314 then
5315 -- C * F(X) in a fixed context, where C is a real literal or a
5316 -- fixed-point expression. F must have either a fixed type
5317 -- interpretation or an integer interpretation, but not both.
5324 else
5331 else
5339 -- Reanalyze the literal with the fixed type of the context. If
5340 -- context is Universal_Fixed, we are within a conversion, leave
5341 -- the literal as a universal real because there is no usable
5342 -- fixed type, and the target of the conversion plays no role in
5343 -- the resolution.
5345 declare
5349 begin
5352 else
5358 then
5360 else
5368 -- A universal real conditional expression can appear in a fixed-type
5369 -- context and must be resolved with that context to facilitate the
5370 -- code generation to the backend.
5375 then
5378 else
5383 ----------------------
5384 -- Set_Operand_Type --
5385 ----------------------
5388 begin
5391 then
5396 -- Start of processing for Resolve_Arithmetic_Op
5398 begin
5403 then
5407 -- Special-case for mixed-mode universal expressions or fixed point type
5408 -- operation: each argument is resolved separately. The same treatment
5409 -- is required if one of the operands of a fixed point operation is
5410 -- universal real, since in this case we don't do a conversion to a
5411 -- specific fixed-point type (instead the expander handles the case).
5413 -- Set the type of the node to its universal interpretation because
5414 -- legality checks on an exponentiation operand need the context.
5419 then
5430 or else
5433 then
5438 -- If context is a fixed type and one operand is integer, the other
5439 -- is resolved with the type of the context.
5444 then
5451 then
5455 else
5460 -- Check the rule in RM05-4.5.5(19.1/2) disallowing universal_fixed
5461 -- multiplying operators from being used when the expected type is
5462 -- also universal_fixed. Note that B_Typ will be Universal_Fixed in
5463 -- some cases where the expected type is actually Any_Real;
5464 -- Expected_Type_Is_Any_Real takes care of that case.
5468 then
5472 N_Unchecked_Type_Conversion)
5473 then
5480 else
5483 and then not
5485 N_Unchecked_Type_Conversion)
5486 then
5487 Error_Msg_N
5492 -- The expected type is "any real type" in contexts like
5494 -- type T is delta <universal_fixed-expression> ...
5496 -- in which case we need to set the type to Universal_Real
5497 -- so that static expression evaluation will work properly.
5501 else
5511 then
5516 -- If no previous errors, this is only possible if one operand is
5517 -- overloaded and the context is universal. Resolve as such.
5522 else
5524 and then
5526 then
5530 -- If the context is Universal_Fixed and the operands are also
5531 -- universal fixed, this is an error, unless there is only one
5532 -- applicable fixed_point type (usually Duration).
5540 else
5545 else
5550 -- If one of the arguments was resolved to a non-universal type.
5551 -- label the result of the operation itself with the same type.
5552 -- Do the same for the universal argument, if any.
5564 -- In SPARK, a multiplication or division with operands of fixed point
5565 -- types must be qualified or explicitly converted to identify the
5566 -- result type.
5571 and then
5573 then
5574 Check_SPARK_05_Restriction
5578 -- Set overflow and division checking bit
5585 -- Give warning if explicit division by zero
5589 then
5595 or else
5598 then
5599 -- Specialize the warning message according to the operation.
5600 -- When SPARK_Mode is On, force a warning instead of an error
5601 -- in that case, as this likely corresponds to deactivated
5602 -- code. The following warnings are for the case
5607 -- For division, we have two cases, for float division
5608 -- of an unconstrained float type, on a machine where
5609 -- Machine_Overflows is false, we don't get an exception
5610 -- at run-time, but rather an infinity or Nan. The Nan
5611 -- case is pretty obscure, so just warn about infinities.
5615 and then not Machine_Overflows_On_Target
5616 then
5617 Error_Msg_N
5621 -- For all other cases, we get a Constraint_Error
5623 else
5624 Apply_Compile_Time_Constraint_Error
5631 Apply_Compile_Time_Constraint_Error
5637 Apply_Compile_Time_Constraint_Error
5642 -- Division by zero can only happen with division, rem,
5643 -- and mod operations.
5649 -- In GNATprove mode, we enable the division check so that
5650 -- GNATprove will issue a message if it cannot be proved.
5656 -- Otherwise just set the flag to check at run time
5658 else
5663 -- If Restriction No_Implicit_Conditionals is active, then it is
5664 -- violated if either operand can be negative for mod, or for rem
5665 -- if both operands can be negative.
5669 then
5670 declare
5677 -- Set if corresponding operand might be negative
5679 begin
5680 Determine_Range
5684 Determine_Range
5688 -- Check if we will be generating conditionals. There are two
5689 -- cases where that can happen, first for REM, the only case
5690 -- is largest negative integer mod -1, where the division can
5691 -- overflow, but we still have to give the right result. The
5692 -- front end generates a test for this annoying case. Here we
5693 -- just test if both operands can be negative (that's what the
5694 -- expander does, so we match its logic here).
5696 -- The second case is mod where either operand can be negative.
5697 -- In this case, the back end has to generate additional tests.
5700 or else
5702 then
5713 ------------------
5714 -- Resolve_Call --
5715 ------------------
5718 function Same_Or_Aliased_Subprograms
5721 -- Returns True if the subprogram entity S is the same as E or else
5722 -- S is an alias of E.
5724 ---------------------------------
5725 -- Same_Or_Aliased_Subprograms --
5726 ---------------------------------
5728 function Same_Or_Aliased_Subprograms
5731 is
5733 begin
5737 -- Local variables
5751 -- Start of processing for Resolve_Call
5753 begin
5754 -- The context imposes a unique interpretation with type Typ on a
5755 -- procedure or function call. Find the entity of the subprogram that
5756 -- yields the expected type, and propagate the corresponding formal
5757 -- constraints on the actuals. The caller has established that an
5758 -- interpretation exists, and emitted an error if not unique.
5760 -- First deal with the case of a call to an access-to-subprogram,
5761 -- dereference made explicit in Analyze_Call.
5767 else
5768 -- Find the interpretation whose type (a subprogram type) has a
5769 -- return type that is compatible with the context. Analysis of
5770 -- the node has established that one exists.
5789 -- If the prefix is not an entity, then resolve it
5795 -- For an indirect call, we always invalidate checks, since we do not
5796 -- know whether the subprogram is local or global. Yes we could do
5797 -- better here, e.g. by knowing that there are no local subprograms,
5798 -- but it does not seem worth the effort. Similarly, we kill all
5799 -- knowledge of current constant values.
5801 Kill_Current_Values;
5803 -- If this is a procedure call which is really an entry call, do
5804 -- the conversion of the procedure call to an entry call. Protected
5805 -- operations use the same circuitry because the name in the call
5806 -- can be an arbitrary expression with special resolution rules.
5811 then
5815 -- Kill checks and constant values, as above for indirect case
5816 -- Who knows what happens when another task is activated?
5818 Kill_Current_Values;
5821 -- Normal subprogram call with name established in Resolve
5827 -- Otherwise we must have the case of an overloaded call
5829 else
5832 -- Initialize Nam to prevent warning (we know it will be assigned
5833 -- in the loop below, but the compiler does not know that).
5853 then
5854 -- The prefix is a parameterless function call that returns an access
5855 -- to subprogram. If parameters are present in the current call, add
5856 -- add an explicit dereference. We use the base type here because
5857 -- within an instance these may be subtypes.
5859 -- The dereference is added either in Analyze_Call or here. Should
5860 -- be consolidated ???
5869 -- Check that a call to Current_Task does not occur in an entry body
5872 declare
5875 begin
5877 loop
5880 -- Exclude calls that occur within the default of a formal
5881 -- parameter of the entry, since those are evaluated outside
5882 -- of the body.
5889 then
5892 Error_Msg_NE
5906 -- Check that a procedure call does not occur in the context of the
5907 -- entry call statement of a conditional or timed entry call. Note that
5908 -- the case of a call to a subprogram renaming of an entry will also be
5909 -- rejected. The test for N not being an N_Entry_Call_Statement is
5910 -- defensive, covering the possibility that the processing of entry
5911 -- calls might reach this point due to later modifications of the code
5912 -- above.
5917 then
5921 -- Ada 2005 (AI-345): If a procedure_call_statement is used
5922 -- for a procedure_or_entry_call, the procedure_name or
5923 -- procedure_prefix of the procedure_call_statement shall denote
5924 -- an entry renamed by a procedure, or (a view of) a primitive
5925 -- subprogram of a limited interface whose first parameter is
5926 -- a controlling parameter.
5931 then
5932 Error_Msg_N
5937 -- If the SPARK_05 restriction is active, we are not allowed
5938 -- to have a call to a subprogram before we see its completion.
5943 -- Don't flag strange internal calls
5948 -- Only flag calls in extended main source
5953 -- Exclude enumeration literals from this processing
5956 then
5957 Check_SPARK_05_Restriction
5961 -- Check that this is not a call to a protected procedure or entry from
5962 -- within a protected function.
5966 -- Freeze the subprogram name if not in a spec-expression. Note that
5967 -- we freeze procedure calls as well as function calls. Procedure calls
5968 -- are not frozen according to the rules (RM 13.14(14)) because it is
5969 -- impossible to have a procedure call to a non-frozen procedure in
5970 -- pure Ada, but in the code that we generate in the expander, this
5971 -- rule needs extending because we can generate procedure calls that
5972 -- need freezing.
5974 -- In Ada 2012, expression functions may be called within pre/post
5975 -- conditions of subsequent functions or expression functions. Such
5976 -- calls do not freeze when they appear within generated bodies,
5977 -- (including the body of another expression function) which would
5978 -- place the freeze node in the wrong scope. An expression function
5979 -- is frozen in the usual fashion, by the appearance of a real body,
5980 -- or at the end of a declarative part.
5983 and then not In_Spec_Expression
5985 and then
5988 then
5992 -- For a predefined operator, the type of the result is the type imposed
5993 -- by context, except for a predefined operation on universal fixed.
5994 -- Otherwise The type of the call is the type returned by the subprogram
5995 -- being called.
6002 -- If the subprogram returns an array type, and the context requires the
6003 -- component type of that array type, the node is really an indexing of
6004 -- the parameterless call. Resolve as such. A pathological case occurs
6005 -- when the type of the component is an access to the array type. In
6006 -- this case the call is truly ambiguous. If the call is to an intrinsic
6007 -- subprogram, it can't be an indexed component. This check is necessary
6008 -- because if it's Unchecked_Conversion, and we have "type T_Ptr is
6009 -- access T;" and "type T is array (...) of T_Ptr;" (i.e. an array of
6010 -- pointers to the same array), the compiler gets confused and does an
6011 -- infinite recursion.
6014 and then
6017 or else
6020 and then
6023 then
6024 declare
6029 begin
6032 then
6033 Error_Msg_N
6035 else
6038 -- The called entity may be an explicit dereference, in which
6039 -- case there is no entity to set.
6047 or else
6049 and then
6051 then
6054 -- Indexed call to a parameterless function
6056 Index_Node :=
6058 Prefix =>
6061 else
6062 -- An Ada 2005 prefixed call to a primitive operation
6063 -- whose first parameter is the prefix. This prefix was
6064 -- prepended to the parameter list, which is actually a
6065 -- list of indexes. Remove the prefix in order to build
6066 -- the proper indexed component.
6068 Index_Node :=
6070 Prefix =>
6073 Parameter_Associations =>
6074 New_List
6079 -- Preserve the parenthesis count of the node
6083 -- Since we are correcting a node classification error made
6084 -- by the parser, we call Replace rather than Rewrite.
6098 else
6099 -- If the called function is not declared in the main unit and it
6100 -- returns the limited view of type then use the available view (as
6101 -- is done in Try_Object_Operation) to prevent back-end confusion;
6102 -- for the function entity itself. The call must appear in a context
6103 -- where the nonlimited view is available. If the function entity is
6104 -- in the extended main unit then no action is needed, because the
6105 -- back end handles this case. In either case the type of the call
6106 -- is the nonlimited view.
6110 then
6117 else
6122 -- In the case where the call is to an overloaded subprogram, Analyze
6123 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
6124 -- such a case Normalize_Actuals needs to be called once more to order
6125 -- the actuals correctly. Otherwise the call will have the ordering
6126 -- given by the last overloaded subprogram whether this is the correct
6127 -- one being called or not.
6134 -- In any case, call is fully resolved now. Reset Overload flag, to
6135 -- prevent subsequent overload resolution if node is analyzed again
6140 -- A Ghost entity must appear in a specific context
6146 -- If we are calling the current subprogram from immediately within its
6147 -- body, then that is the case where we can sometimes detect cases of
6148 -- infinite recursion statically. Do not try this in case restriction
6149 -- No_Recursion is in effect anyway, and do it only for source calls.
6154 -- Check violation of SPARK_05 restriction which does not permit
6155 -- a subprogram body to contain a call to the subprogram directly.
6159 then
6160 Check_SPARK_05_Restriction
6164 -- Issue warning for possible infinite recursion in the absence
6165 -- of the No_Recursion restriction.
6170 then
6171 -- Here we detected and flagged an infinite recursion, so we do
6172 -- not need to test the case below for further warnings. Also we
6173 -- are all done if we now have a raise SE node.
6179 -- If call is to immediately containing subprogram, then check for
6180 -- the case of a possible run-time detectable infinite recursion.
6182 else
6186 -- Although in general case, recursion is not statically
6187 -- checkable, the case of calling an immediately containing
6188 -- subprogram is easy to catch.
6192 -- If the recursive call is to a parameterless subprogram,
6193 -- then even if we can't statically detect infinite
6194 -- recursion, this is pretty suspicious, and we output a
6195 -- warning. Furthermore, we will try later to detect some
6196 -- cases here at run time by expanding checking code (see
6197 -- Detect_Infinite_Recursion in package Exp_Ch6).
6199 -- If the recursive call is within a handler, do not emit a
6200 -- warning, because this is a common idiom: loop until input
6201 -- is correct, catch illegal input in handler and restart.
6207 then
6208 -- For the case of a procedure call. We give the message
6209 -- only if the call is the first statement in a sequence
6210 -- of statements, or if all previous statements are
6211 -- simple assignments. This is simply a heuristic to
6212 -- decrease false positives, without losing too many good
6213 -- warnings. The idea is that these previous statements
6214 -- may affect global variables the procedure depends on.
6215 -- We also exclude raise statements, that may arise from
6216 -- constraint checks and are probably unrelated to the
6217 -- intended control flow.
6221 then
6222 declare
6224 begin
6228 N_Raise_Constraint_Error)
6229 then
6238 -- Do not give warning if we are in a conditional context
6240 declare
6242 begin
6248 then
6253 -- Here warning is to be issued
6269 -- Check obsolescent reference to Ada.Characters.Handling subprogram
6273 -- If subprogram name is a predefined operator, it was given in
6274 -- functional notation. Replace call node with operator node, so
6275 -- that actuals can be resolved appropriately.
6283 then
6289 -- Create a transient scope if the resulting type requires it
6291 -- There are several notable exceptions:
6293 -- a) In init procs, the transient scope overhead is not needed, and is
6294 -- even incorrect when the call is a nested initialization call for a
6295 -- component whose expansion may generate adjust calls. However, if the
6296 -- call is some other procedure call within an initialization procedure
6297 -- (for example a call to Create_Task in the init_proc of the task
6298 -- run-time record) a transient scope must be created around this call.
6300 -- b) Enumeration literal pseudo-calls need no transient scope
6302 -- c) Intrinsic subprograms (Unchecked_Conversion and source info
6303 -- functions) do not use the secondary stack even though the return
6304 -- type may be unconstrained.
6306 -- d) Calls to a build-in-place function, since such functions may
6307 -- allocate their result directly in a target object, and cases where
6308 -- the result does get allocated in the secondary stack are checked for
6309 -- within the specialized Exp_Ch6 procedures for expanding those
6310 -- build-in-place calls.
6312 -- e) Calls to inlinable expression functions do not use the secondary
6313 -- stack (since the call will be replaced by its returned object).
6315 -- f) If the subprogram is marked Inline_Always, then even if it returns
6316 -- an unconstrained type the call does not require use of the secondary
6317 -- stack. However, inlining will only take place if the body to inline
6318 -- is already present. It may not be available if e.g. the subprogram is
6319 -- declared in a child instance.
6321 -- If this is an initialization call for a type whose construction
6322 -- uses the secondary stack, and it is not a nested call to initialize
6323 -- a component, we do need to create a transient scope for it. We
6324 -- check for this by traversing the type in Check_Initialization_Call.
6330 then
6337 then
6340 elsif Expander_Active
6343 and then
6345 or else
6347 then
6350 -- If the call appears within the bounds of a loop, it will
6351 -- be rewritten and reanalyzed, nothing left to do here.
6358 and then not Within_Init_Proc
6359 then
6363 -- A protected function cannot be called within the definition of the
6364 -- enclosing protected type, unless it is part of a pre/postcondition
6365 -- on another protected operation. This may appear in the entry wrapper
6366 -- created for an entry with preconditions.
6371 and then not In_Spec_Expression
6373 then
6374 Error_Msg_NE
6378 -- Propagate interpretation to actuals, and add default expressions
6379 -- where needed.
6384 -- Overloaded literals are rewritten as function calls, for purpose of
6385 -- resolution. After resolution, we can replace the call with the
6386 -- literal itself.
6392 -- Avoid validation, since it is a static function call
6398 -- If the subprogram is not global, then kill all saved values and
6399 -- checks. This is a bit conservative, since in many cases we could do
6400 -- better, but it is not worth the effort. Similarly, we kill constant
6401 -- values. However we do not need to do this for internal entities
6402 -- (unless they are inherited user-defined subprograms), since they
6403 -- are not in the business of molesting local values.
6405 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
6406 -- kill all checks and values for calls to global subprograms. This
6407 -- takes care of the case where an access to a local subprogram is
6408 -- taken, and could be passed directly or indirectly and then called
6409 -- from almost any context.
6411 -- Note: we do not do this step till after resolving the actuals. That
6412 -- way we still take advantage of the current value information while
6413 -- scanning the actuals.
6415 -- We suppress killing values if we are processing the nodes associated
6416 -- with N_Freeze_Entity nodes. Otherwise the declaration of a tagged
6417 -- type kills all the values as part of analyzing the code that
6418 -- initializes the dispatch tables.
6422 or else Suppress_Value_Tracking_On_Call
6427 then
6428 Kill_Current_Values;
6431 -- If we are warning about unread OUT parameters, this is the place to
6432 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
6433 -- after the above call to Kill_Current_Values (since that call clears
6434 -- the Last_Assignment field of all local variables).
6439 then
6440 declare
6444 begin
6454 then
6464 -- If the subprogram is a primitive operation, check whether or not
6465 -- it is a correct dispatching call.
6469 then
6474 and then not In_Instance
6475 then
6479 -- If this is a dispatching call, generate the appropriate reference,
6480 -- for better source navigation in GPS.
6484 then
6487 -- Normal case, not a dispatching call: generate a call reference
6489 else
6497 -- Check for violation of restriction No_Specific_Termination_Handlers
6498 -- and warn on a potentially blocking call to Abort_Task.
6502 or else
6504 then
6511 -- A call to Ada.Real_Time.Timing_Events.Set_Handler to set a relative
6512 -- timing event violates restriction No_Relative_Delay (AI-0211). We
6513 -- need to check the second argument to determine whether it is an
6514 -- absolute or relative timing event.
6519 then
6523 -- Issue an error for a call to an eliminated subprogram. This routine
6524 -- will not perform the check if the call appears within a default
6525 -- expression.
6529 -- In formal mode, the primitive operations of a tagged type or type
6530 -- extension do not include functions that return the tagged type.
6536 then
6540 -- Implement rule in 12.5.1 (23.3/2): In an instance, if the actual is
6541 -- class-wide and the call dispatches on result in a context that does
6542 -- not provide a tag, the call raises Program_Error.
6545 and then In_Instance
6550 then
6551 -- Verify that none of the formals are controlling
6553 declare
6557 begin
6579 -- Check for calling a function with OUT or IN OUT parameter when the
6580 -- calling context (us right now) is not Ada 2012, so does not allow
6581 -- OUT or IN OUT parameters in function calls. Functions declared in
6582 -- a predefined unit are OK, as they may be called indirectly from a
6583 -- user-declared instantiation.
6589 then
6594 -- Check the dimensions of the actuals in the call. For function calls,
6595 -- propagate the dimensions from the returned type to N.
6599 -- All done, evaluate call and deal with elaboration issues
6604 -- In GNATprove mode, expansion is disabled, but we want to inline some
6605 -- subprograms to facilitate formal verification. Indirect calls through
6606 -- a subprogram type or within a generic cannot be inlined. Inlining is
6607 -- performed only for calls subject to SPARK_Mode on.
6609 if GNATprove_Mode
6612 and then not Inside_A_Generic
6613 then
6620 -- Nothing to do if the subprogram is not eligible for inlining in
6621 -- GNATprove mode, or inlining is disabled with switch -gnatdm
6625 or else Debug_Flag_M
6626 then
6629 -- Calls cannot be inlined inside assertions, as GNATprove treats
6630 -- assertions as logic expressions.
6633 Cannot_Inline
6636 -- Calls cannot be inlined inside default expressions
6639 Cannot_Inline
6642 -- Inlining should not be performed during pre-analysis
6646 -- With the one-pass inlining technique, a call cannot be
6647 -- inlined if the corresponding body has not been seen yet.
6650 Cannot_Inline
6653 -- Nothing to do if there is no body to inline, indicating that
6654 -- the subprogram is not suitable for inlining in GNATprove
6655 -- mode.
6660 -- Do not inline calls inside expression functions, as this
6661 -- would prevent interpreting them as logical formulas in
6662 -- GNATprove.
6665 and then
6667 then
6668 Cannot_Inline
6672 -- Calls cannot be inlined inside potentially unevaluated
6673 -- expressions, as this would create complex actions inside
6674 -- expressions, that are not handled by GNATprove.
6677 Cannot_Inline
6681 -- Do not inline calls which would possibly lead to missing a
6682 -- type conversion check on an input parameter.
6685 Cannot_Inline
6689 -- Otherwise, inline the call
6691 else
6701 -----------------------------
6702 -- Resolve_Case_Expression --
6703 -----------------------------
6711 begin
6718 -- When the expression is of a scalar subtype different from the
6719 -- result subtype, then insert a conversion to ensure the generation
6720 -- of a constraint check.
6730 -- Apply RM 4.5.7 (17/3): whether the expression is statically or
6731 -- dynamically tagged must be known statically.
6739 Error_Msg_N
6752 -------------------------------
6753 -- Resolve_Character_Literal --
6754 -------------------------------
6760 begin
6761 -- Verify that the character does belong to the type of the context
6766 -- Wide_Wide_Character literals must always be defined, since the set
6767 -- of wide wide character literals is complete, i.e. if a character
6768 -- literal is accepted by the parser, then it is OK for wide wide
6769 -- character (out of range character literals are rejected).
6774 -- Always accept character literal for type Any_Character, which
6775 -- occurs in error situations and in comparisons of literals, both
6776 -- of which should accept all literals.
6781 -- For Standard.Character or a type derived from it, check that the
6782 -- literal is in range.
6789 -- For Standard.Wide_Character or a type derived from it, check that the
6790 -- literal is in range.
6797 -- If the entity is already set, this has already been resolved in a
6798 -- generic context, or comes from expansion. Nothing else to do.
6803 -- Otherwise we have a user defined character type, and we can use the
6804 -- standard visibility mechanisms to locate the referenced entity.
6806 else
6819 -- If we fall through, then the literal does not match any of the
6820 -- entries of the enumeration type. This isn't just a constraint error
6821 -- situation, it is an illegality (see RM 4.2).
6823 Error_Msg_NE
6827 ---------------------------
6828 -- Resolve_Comparison_Op --
6829 ---------------------------
6831 -- Context requires a boolean type, and plays no role in resolution.
6832 -- Processing identical to that for equality operators. The result type is
6833 -- the base type, which matters when pathological subtypes of booleans with
6834 -- limited ranges are used.
6841 begin
6842 -- If this is an intrinsic operation which is not predefined, use the
6843 -- types of its declared arguments to resolve the possibly overloaded
6844 -- operands. Otherwise the operands are unambiguous and specify the
6845 -- expected type.
6850 else
6861 -- Skip remaining processing if already set to Any_Type
6867 -- Deal with other error cases
6871 T = Any_Character
6872 then
6875 else
6883 -- Resolve the operands if types OK
6892 -- In SPARK, ordering operators <, <=, >, >= are not defined for Boolean
6893 -- types or array types except String.
6896 Check_SPARK_05_Restriction
6901 then
6902 Check_SPARK_05_Restriction
6906 -- Check comparison on unordered enumeration
6910 Error_Msg_NE
6917 -- Evaluate the relation (note we do this after the above check since
6918 -- this Eval call may change N to True/False. Skip this evaluation
6919 -- inside assertions, in order to keep assertions as written by users
6920 -- for tools that rely on these, e.g. GNATprove for loop invariants.
6921 -- Except evaluation is still performed even inside assertions for
6922 -- comparisons between values of universal type, which are useless
6923 -- for static analysis tools, and not supported even by GNATprove.
6927 and then
6929 then
6934 -----------------------------------------
6935 -- Resolve_Discrete_Subtype_Indication --
6936 -----------------------------------------
6938 procedure Resolve_Discrete_Subtype_Indication
6941 is
6945 begin
6953 else
6963 Error_Msg_NE
6966 -- Rewrite the constraint as a range of Typ
6967 -- to allow compilation to proceed further.
6979 else
6983 -- Additionally, we must check that the bounds are compatible
6984 -- with the given subtype, which might be different from the
6985 -- type of the context.
6989 -- ??? If the above check statically detects a Constraint_Error
6990 -- it replaces the offending bound(s) of the range R with a
6991 -- Constraint_Error node. When the itype which uses these bounds
6992 -- is frozen the resulting call to Duplicate_Subexpr generates
6993 -- a new temporary for the bounds.
6995 -- Unfortunately there are other itypes that are also made depend
6996 -- on these bounds, so when Duplicate_Subexpr is called they get
6997 -- a forward reference to the newly created temporaries and Gigi
6998 -- aborts on such forward references. This is probably sign of a
6999 -- more fundamental problem somewhere else in either the order of
7000 -- itype freezing or the way certain itypes are constructed.
7002 -- To get around this problem we call Remove_Side_Effects right
7003 -- away if either bounds of R are a Constraint_Error.
7005 declare
7009 begin
7025 -------------------------
7026 -- Resolve_Entity_Name --
7027 -------------------------
7029 -- Used to resolve identifiers and expanded names
7032 function Is_Assignment_Or_Object_Expression
7035 -- Determine whether node Context denotes an assignment statement or an
7036 -- object declaration whose expression is node Expr.
7038 ----------------------------------------
7039 -- Is_Assignment_Or_Object_Expression --
7040 ----------------------------------------
7042 function Is_Assignment_Or_Object_Expression
7045 is
7046 begin
7048 N_Object_Declaration)
7050 then
7053 -- Check whether a construct that yields a name is the expression of
7054 -- an assignment statement or an object declaration.
7057 N_Explicit_Dereference,
7058 N_Indexed_Component,
7059 N_Selected_Component,
7060 N_Slice)
7062 or else
7064 N_Unchecked_Type_Conversion)
7066 then
7067 return
7068 Is_Assignment_Or_Object_Expression
7072 -- Otherwise the context is not an assignment statement or an object
7073 -- declaration.
7075 else
7080 -- Local variables
7085 -- Start of processing for Resolve_Entity_Name
7087 begin
7088 -- If garbage from errors, set to Any_Type and return
7095 -- Replace named numbers by corresponding literals. Note that this is
7096 -- the one case where Resolve_Entity_Name must reset the Etype, since
7097 -- it is currently marked as universal.
7107 -- For enumeration literals, we need to make sure that a proper style
7108 -- check is done, since such literals are overloaded, and thus we did
7109 -- not do a style check during the first phase of analysis.
7115 -- Case of (sub)type name appearing in a context where an expression
7116 -- is expected. This is legal if occurrence is a current instance.
7117 -- See RM 8.6 (17/3).
7123 -- Any other use is an error
7125 else
7126 Error_Msg_N
7130 -- Check discriminant use if entity is discriminant in current scope,
7131 -- i.e. discriminant of record or concurrent type currently being
7132 -- analyzed. Uses in corresponding body are unrestricted.
7137 then
7140 -- A parameterless generic function cannot appear in a context that
7141 -- requires resolution.
7146 -- In Ada 83 an OUT parameter cannot be read
7151 or else Is_Assignment_Or_Object_Expression
7154 then
7159 -- In all other cases, just do the possible static evaluation
7161 else
7162 -- A deferred constant that appears in an expression must have a
7163 -- completion, unless it has been removed by in-place expansion of
7164 -- an aggregate. A constant that is a renaming does not need
7165 -- initialization.
7171 and then not In_Spec_Expression
7174 then
7178 then
7180 else
7181 Error_Msg_N
7191 -- When the entity appears in a parameter association, retrieve the
7192 -- related subprogram call.
7200 -- The following checks are only relevant when SPARK_Mode is on as
7201 -- they are not standard Ada legality rules.
7205 -- An effectively volatile object subject to enabled properties
7206 -- Async_Writers or Effective_Reads must appear in non-interfering
7207 -- context (SPARK RM 7.1.3(12)).
7214 then
7215 SPARK_Msg_N
7220 -- Check for possible elaboration issues with respect to reads of
7221 -- variables. The act of renaming the variable is not considered a
7222 -- read as it simply establishes an alias.
7225 and then Dynamic_Elaboration_Checks
7227 then
7231 -- The variable may eventually become a constituent of a single
7232 -- protected/task type. Record the reference now and verify its
7233 -- legality when analyzing the contract of the variable
7234 -- (SPARK RM 9.3).
7241 -- A Ghost entity must appear in a specific context
7249 -------------------
7250 -- Resolve_Entry --
7251 -------------------
7263 -- If the bounds of the entry family being called depend on task
7264 -- discriminants, build a new index subtype where a discriminant is
7265 -- replaced with the value of the discriminant of the target task.
7266 -- The target task is the prefix of the entry name in the call.
7268 -----------------------
7269 -- Actual_Index_Type --
7270 -----------------------
7280 -- If the bound is given by a discriminant, replace with a reference
7281 -- to the discriminant of the same name in the target task. If the
7282 -- entry name is the target of a requeue statement and the entry is
7283 -- in the current protected object, the bound to be used is the
7284 -- discriminal of the object (see Apply_Range_Checks for details of
7285 -- the transformation).
7287 -----------------------------
7288 -- Actual_Discriminant_Ref --
7289 -----------------------------
7295 begin
7300 then
7306 then
7307 -- Note: here Bound denotes a discriminant of the corresponding
7308 -- record type tskV, whose discriminal is a formal of the
7309 -- init-proc tskVIP. What we want is the body discriminal,
7310 -- which is associated to the discriminant of the original
7311 -- concurrent type tsk.
7313 return New_Occurrence_Of
7316 else
7317 Ref :=
7327 -- Start of processing for Actual_Index_Type
7329 begin
7332 then
7335 else
7349 -- Start of processing for Resolve_Entry
7351 begin
7352 -- Find name of entry being called, and resolve prefix of name with its
7353 -- own type. The prefix can be overloaded, and the name and signature of
7354 -- the entry must be taken into account.
7358 -- Case of dealing with entry family within the current tasks
7362 else
7368 -- Entry call to an entry (or entry family) in the current task. This
7369 -- is legal even though the task will deadlock. Rewrite as call to
7370 -- current task.
7372 -- This can also be a call to an entry in an enclosing task. If this
7373 -- is a single task, we have to retrieve its name, because the scope
7374 -- of the entry is the task type, not the object. If the enclosing
7375 -- task is a task type, the identity of the task is given by its own
7376 -- self variable.
7378 -- Finally this can be a requeue on an entry of the same task or
7379 -- protected object.
7386 then
7387 -- S is an enclosing task or protected object. The concurrent
7388 -- declaration has been converted into a type declaration, and
7389 -- the object itself has an object declaration that follows
7390 -- the type in the same declarative part.
7402 -- Call to current task. Will be transformed into call to Self
7409 New_N :=
7412 Selector_Name =>
7419 then
7420 -- Use the entry name (which must be unique at this point) to find
7421 -- the prefix that returns the corresponding task/protected type.
7423 declare
7429 begin
7451 -- Up to this point the expression could have been the actual in a
7452 -- simple entry call, and be given by a named association.
7456 else
7462 ------------------------
7463 -- Resolve_Entry_Call --
7464 ------------------------
7476 begin
7477 -- We kill all checks here, because it does not seem worth the effort to
7478 -- do anything better, an entry call is a big operation.
7480 Kill_All_Checks;
7482 -- Processing of the name is similar for entry calls and protected
7483 -- operation calls. Once the entity is determined, we can complete
7484 -- the resolution of the actuals.
7486 -- The selector may be overloaded, in the case of a protected object
7487 -- with overloaded functions. The type of the context is used for
7488 -- resolution.
7493 then
7494 declare
7498 begin
7517 -- Simple entry call
7525 -- Call to member of entry family
7532 -- We cannot in general check the maximum depth of protected entry calls
7533 -- at compile time. But we can tell that any protected entry call at all
7534 -- violates a specified nesting depth of zero.
7540 -- Use context type to disambiguate a protected function that can be
7541 -- called without actuals and that returns an array type, and where the
7542 -- argument list may be an indexing of the returned value.
7547 and then
7553 and then
7554 Covers
7557 then
7558 declare
7561 begin
7562 Index_Node :=
7564 Prefix =>
7568 -- Since we are correcting a node classification error made by the
7569 -- parser, we call Replace rather than Rewrite.
7582 then
7584 -- Note the entity being called before rewriting the call, so that
7585 -- it appears used at this point.
7589 -- Rewrite as call to the precondition wrapper, adding the task
7590 -- object to the list of actuals. If the call is to a member of an
7591 -- entry family, include the index as well.
7593 declare
7597 begin
7606 New_Call :=
7608 Name =>
7613 -- Preanalyze and resolve new call. Current procedure is called
7614 -- from Resolve_Call, after which expansion will take place.
7621 -- The operation name may have been overloaded. Order the actuals
7622 -- according to the formals of the resolved entity, and set the return
7623 -- type to that of the operation.
7630 -- Reset the Is_Overloaded flag, since resolution is now completed
7632 -- Simple entry call
7637 -- Call to a member of an entry family
7647 -- Create a call reference to the entry
7655 -- Verify that a procedure call cannot masquerade as an entry
7656 -- call where an entry call is expected.
7661 then
7666 then
7671 then
7676 -- After resolution, entry calls and protected procedure calls are
7677 -- changed into entry calls, for expansion. The structure of the node
7678 -- does not change, so it can safely be done in place. Protected
7679 -- function calls must keep their structure because they are
7680 -- subexpressions.
7684 -- A protected operation that is not a function may modify the
7685 -- corresponding object, and cannot apply to a constant. If this
7686 -- is an internal call, the prefix is the type itself.
7692 then
7693 Error_Msg_N
7695 Entry_Name);
7709 -- Protected functions can return on the secondary stack, in which
7710 -- case we must trigger the transient scope mechanism.
7712 elsif Expander_Active
7714 then
7719 -------------------------
7720 -- Resolve_Equality_Op --
7721 -------------------------
7723 -- Both arguments must have the same type, and the boolean context does
7724 -- not participate in the resolution. The first pass verifies that the
7725 -- interpretation is not ambiguous, and the type of the left argument is
7726 -- correctly set, or is Any_Type in case of ambiguity. If both arguments
7727 -- are strings or aggregates, allocators, or Null, they are ambiguous even
7728 -- though they carry a single (universal) type. Diagnose this case here.
7736 -- The resolution rule for if expressions requires that each such must
7737 -- have a unique type. This means that if several dependent expressions
7738 -- are of a non-null anonymous access type, and the context does not
7739 -- impose an expected type (as can be the case in an equality operation)
7740 -- the expression must be rejected.
7743 -- Attempt to explain the nature of a redundant comparison with True. If
7744 -- the expression N is too complex, this routine issues a general error
7745 -- message.
7748 -- In the case of allocators and access attributes, the context must
7749 -- provide an indication of the specific access type to be used. If
7750 -- one operand is of such a "generic" access type, check whether there
7751 -- is a specific visible access type that has the same designated type.
7752 -- This is semantically dubious, and of no interest to any real code,
7753 -- but c48008a makes it all worthwhile.
7755 -------------------------
7756 -- Check_If_Expression --
7757 -------------------------
7763 begin
7770 then
7776 ------------------------
7777 -- Explain_Redundancy --
7778 ------------------------
7785 begin
7788 -- Strip the operand down to an entity
7790 loop
7793 else
7798 -- The construct denotes an entity
7803 -- Do not generate an error message when the comparison is done
7804 -- against the enumeration literal Standard.True.
7808 -- Build a customized error message
7835 -- The construct is too complex to disect, issue a general message
7837 else
7842 -----------------------------
7843 -- Find_Unique_Access_Type --
7844 -----------------------------
7851 begin
7853 E_Access_Attribute_Type)
7854 then
7858 E_Access_Attribute_Type)
7859 then
7861 else
7873 then
7886 -- Start of processing for Resolve_Equality_Op
7888 begin
7899 T = Any_Character
7900 then
7903 else
7912 then
7921 -- If expressions must have a single type, and if the context does
7922 -- not impose one the dependent expressions cannot be anonymous
7923 -- access types.
7925 -- Why no similar processing for case expressions???
7929 E_Anonymous_Access_Subprogram_Type)
7931 E_Anonymous_Access_Subprogram_Type)
7932 then
7940 -- In SPARK, equality operators = and /= for array types other than
7941 -- String are only defined when, for each index position, the
7942 -- operands have equal static bounds.
7946 -- Protect call to Matching_Static_Array_Bounds to avoid costly
7947 -- operation if not needed.
7955 then
7956 Check_SPARK_05_Restriction
7961 -- If the unique type is a class-wide type then it will be expanded
7962 -- into a dispatching call to the predefined primitive. Therefore we
7963 -- check here for potential violation of such restriction.
7969 if Warn_On_Redundant_Constructs
7974 then
7975 Error_Msg_N -- CODEFIX
7985 -- If this is an inequality, it may be the implicit inequality
7986 -- created for a user-defined operation, in which case the corres-
7987 -- ponding equality operation is not intrinsic, and the operation
7988 -- cannot be constant-folded. Else fold.
7993 or else Is_Intrinsic_Subprogram
7995 then
8001 then
8005 -- Ada 2005: If one operand is an anonymous access type, convert the
8006 -- other operand to it, to ensure that the underlying types match in
8007 -- the back-end. Same for access_to_subprogram, and the conversion
8008 -- verifies that the types are subtype conformant.
8010 -- We apply the same conversion in the case one of the operands is a
8011 -- private subtype of the type of the other.
8013 -- Why the Expander_Active test here ???
8015 if Expander_Active
8016 and then
8018 E_Anonymous_Access_Subprogram_Type)
8020 then
8040 ----------------------------------
8041 -- Resolve_Explicit_Dereference --
8042 ----------------------------------
8050 -- The candidate prefix type, if overloaded
8055 begin
8059 -- A useful optimization: check whether the dereference denotes an
8060 -- element of a container, and if so rewrite it as a call to the
8061 -- corresponding Element function.
8063 -- Disabled for now, on advice of ARG. A more restricted form of the
8064 -- predicate might be acceptable ???
8066 -- if Is_Container_Element (N) then
8067 -- return;
8068 -- end if;
8072 -- Use the context type to select the prefix that has the correct
8073 -- designated type. Keep the first match, which will be the inner-
8074 -- most.
8081 then
8086 -- Remove access types that do not match, but preserve access
8087 -- to subprogram interpretations, in case a further dereference
8088 -- is needed (see below).
8101 else
8102 -- If no interpretation covers the designated type of the prefix,
8103 -- this is the pathological case where not all implementations of
8104 -- the prefix allow the interpretation of the node as a call. Now
8105 -- that the expected type is known, Remove other interpretations
8106 -- from prefix, rewrite it as a call, and resolve again, so that
8107 -- the proper call node is generated.
8118 New_N :=
8120 Name =>
8131 -- If not overloaded, resolve P with its own type
8133 else
8137 -- If the prefix might be null, add an access check
8141 then
8145 -- If the designated type is a packed unconstrained array type, and the
8146 -- explicit dereference is not in the context of an attribute reference,
8147 -- then we must compute and set the actual subtype, since it is needed
8148 -- by Gigi. The reason we exclude the attribute case is that this is
8149 -- handled fine by Gigi, and in fact we use such attributes to build the
8150 -- actual subtype. We also exclude generated code (which builds actual
8151 -- subtypes directly if they are needed).
8158 then
8164 -- Note: No Eval processing is required for an explicit dereference,
8165 -- because such a name can never be static.
8169 -------------------------------------
8170 -- Resolve_Expression_With_Actions --
8171 -------------------------------------
8174 begin
8177 -- If N has no actions, and its expression has been constant folded,
8178 -- then rewrite N as just its expression. Note, we can't do this in
8179 -- the general case of Is_Empty_List (Actions (N)) as this would cause
8180 -- Expression (N) to be expanded again.
8184 then
8189 ----------------------------------
8190 -- Resolve_Generalized_Indexing --
8191 ----------------------------------
8199 begin
8200 -- In ASIS mode, propagate the information about the indexes back to
8201 -- to the original indexing node. The generalized indexing is either
8202 -- a function call, or a dereference of one. The actuals include the
8203 -- prefix of the original node, which is the container expression.
8212 loop
8221 -- If expression is to be reanalyzed, reset Generalized_Indexing
8222 -- to recreate call node, as is the case when the expression is
8223 -- part of an expression function.
8232 else
8238 ---------------------------
8239 -- Resolve_If_Expression --
8240 ---------------------------
8249 begin
8254 -- When the "then" expression is of a scalar subtype different from the
8255 -- result subtype, then insert a conversion to ensure the generation of
8256 -- a constraint check. The same is done for the else part below, again
8257 -- comparing subtypes rather than base types.
8261 then
8266 -- If ELSE expression present, just resolve using the determined type
8267 -- If type is universal, resolve to any member of the class.
8276 else
8286 -- Apply RM 4.5.7 (17/3): whether the expression is statically or
8287 -- dynamically tagged must be known statically.
8292 then
8298 -- If no ELSE expression is present, root type must be Standard.Boolean
8299 -- and we provide a Standard.True result converted to the appropriate
8300 -- Boolean type (in case it is a derived boolean type).
8303 Else_Expr :=
8308 else
8317 -------------------------------
8318 -- Resolve_Indexed_Component --
8319 -------------------------------
8327 begin
8335 -- Use the context type to select the prefix that yields the correct
8336 -- component type.
8338 declare
8345 begin
8352 and then
8353 Covers
8356 then
8365 else
8371 else
8382 else
8389 -- If prefix is access type, dereference to get real array type.
8390 -- Note: we do not apply an access check because the expander always
8391 -- introduces an explicit dereference, and the check will happen there.
8397 -- If name was overloaded, set component type correctly now
8398 -- If a misplaced call to an entry family (which has no index types)
8399 -- return. Error will be diagnosed from calling context.
8403 else
8410 -- The prefix may have resolved to a string literal, in which case its
8411 -- etype has a special representation. This is only possible currently
8412 -- if the prefix is a static concatenation, written in functional
8413 -- notation.
8418 else
8425 else
8436 -- Do not generate the warning on suspicious index if we are analyzing
8437 -- package Ada.Tags; otherwise we will report the warning with the
8438 -- Prims_Ptr field of the dispatch table.
8441 or else not
8443 Ada_Tags)
8444 then
8449 -- If the array type is atomic, and the component is not atomic, then
8450 -- this is worth a warning, since we have a situation where the access
8451 -- to the component may cause extra read/writes of the atomic array
8452 -- object, or partial word accesses, which could be unexpected.
8458 and then Has_Atomic_Components
8461 then
8462 Error_Msg_N
8464 Error_Msg_N
8469 -----------------------------
8470 -- Resolve_Integer_Literal --
8471 -----------------------------
8474 begin
8479 --------------------------------
8480 -- Resolve_Intrinsic_Operator --
8481 --------------------------------
8490 -- If the operand is a literal, it cannot be the expression in a
8491 -- conversion. Use a qualified expression instead.
8493 ---------------------
8494 -- Convert_Operand --
8495 ---------------------
8501 begin
8503 Res :=
8509 else
8516 -- Start of processing for Resolve_Intrinsic_Operator
8518 begin
8519 -- We must preserve the original entity in a generic setting, so that
8520 -- the legality of the operation can be verified in an instance.
8535 -- If the result or operand types are private, rewrite with unchecked
8536 -- conversions on the operands and the result, to expose the proper
8537 -- underlying numeric type.
8542 then
8547 else
8568 then
8569 -- Add explicit conversion where needed, and save interpretations in
8570 -- case operands are overloaded.
8577 else
8583 else
8593 else
8598 --------------------------------------
8599 -- Resolve_Intrinsic_Unary_Operator --
8600 --------------------------------------
8602 procedure Resolve_Intrinsic_Unary_Operator
8605 is
8610 begin
8629 else
8634 ------------------------
8635 -- Resolve_Logical_Op --
8636 ------------------------
8641 begin
8644 -- Predefined operations on scalar types yield the base type. On the
8645 -- other hand, logical operations on arrays yield the type of the
8646 -- arguments (and the context).
8650 else
8654 -- The following test is required because the operands of the operation
8655 -- may be literals, in which case the resulting type appears to be
8656 -- compatible with a signed integer type, when in fact it is compatible
8657 -- only with modular types. If the context itself is universal, the
8658 -- operation is illegal.
8666 Error_Msg_N
8674 then
8678 -- Replace AND by AND THEN, or OR by OR ELSE, if Short_Circuit_And_Or
8679 -- is active and the result type is standard Boolean (do not mess with
8680 -- ops that return a nonstandard Boolean type, because something strange
8681 -- is going on).
8683 -- Note: you might expect this replacement to be done during expansion,
8684 -- but that doesn't work, because when the pragma Short_Circuit_And_Or
8685 -- is used, no part of the right operand of an "and" or "or" operator
8686 -- should be executed if the left operand would short-circuit the
8687 -- evaluation of the corresponding "and then" or "or else". If we left
8688 -- the replacement to expansion time, then run-time checks associated
8689 -- with such operands would be evaluated unconditionally, due to being
8690 -- before the condition prior to the rewriting as short-circuit forms
8691 -- during expansion.
8693 if Short_Circuit_And_Or
8696 then
8697 -- Mark the corresponding putative SCO operator as truly a logical
8698 -- (and short-circuit) operator.
8711 -- Case of OR changed to OR ELSE
8713 else
8721 -- Return now, since analysis of the rewritten ops will take care of
8722 -- other reference bookkeeping and expression folding.
8737 -- In SPARK, logical operations AND, OR and XOR for arrays are defined
8738 -- only when both operands have same static lower and higher bounds. Of
8739 -- course the types have to match, so only check if operands are
8740 -- compatible and the node itself has no errors.
8744 then
8745 declare
8749 begin
8750 -- Protect call to Matching_Static_Array_Bounds to avoid costly
8751 -- operation if not needed.
8758 then
8759 Check_SPARK_05_Restriction
8766 ---------------------------
8767 -- Resolve_Membership_Op --
8768 ---------------------------
8770 -- The context can only be a boolean type, and does not determine the
8771 -- arguments. Arguments should be unambiguous, but the preference rule for
8772 -- universal types applies.
8782 -- Analysis has determined a unique type for the left operand. Use it to
8783 -- resolve the disjuncts.
8785 ----------------------------
8786 -- Resolve_Set_Membership --
8787 ----------------------------
8793 begin
8794 -- If the left operand is overloaded, find type compatible with not
8795 -- overloaded alternative of the right operand.
8804 else
8809 -- Unclear how to resolve expression if all alternatives are also
8810 -- overloaded.
8816 else
8825 -- Alternative is an expression, a range
8826 -- or a subtype mark.
8830 then
8837 -- Check for duplicates for discrete case
8840 declare
8849 begin
8850 -- Loop checking duplicates. This is quadratic, but giant sets
8851 -- are unlikely in this context so it's a reasonable choice.
8858 N_Character_Literal)
8860 then
8878 -- Start of processing for Resolve_Membership_Op
8880 begin
8886 Resolve_Set_Membership;
8890 and then
8892 or else
8895 then
8898 -- Ada 2005 (AI-251): Support the following case:
8900 -- type I is interface;
8901 -- type T is tagged ...
8903 -- function Test (O : I'Class) is
8904 -- begin
8905 -- return O in T'Class.
8906 -- end Test;
8908 -- In this case we have nothing else to do. The membership test will be
8909 -- done at run time.
8916 then
8918 else
8922 -- If mixed-mode operations are present and operands are all literal,
8923 -- the only interpretation involves Duration, which is probably not
8924 -- the intention of the programmer.
8939 then
8945 else
8950 -- Here after resolving membership operation
8957 ------------------
8958 -- Resolve_Null --
8959 ------------------
8964 begin
8965 -- Handle restriction against anonymous null access values This
8966 -- restriction can be turned off using -gnatdj.
8968 -- Ada 2005 (AI-231): Remove restriction
8971 and then not Debug_Flag_J
8974 then
8975 -- In the common case of a call which uses an explicitly null value
8976 -- for an access parameter, give specialized error message.
8979 Error_Msg_N
8982 -- Standard message for all other cases (are there any?)
8984 else
8985 Error_Msg_N
8990 -- Ada 2005 (AI-231): Generate the null-excluding check in case of
8991 -- assignment to a null-excluding object
8996 then
8998 Insert_Action
9003 else
9010 -- In a distributed context, null for a remote access to subprogram may
9011 -- need to be replaced with a special record aggregate. In this case,
9012 -- return after having done the transformation.
9017 then
9021 -- The null literal takes its type from the context
9026 -----------------------
9027 -- Resolve_Op_Concat --
9028 -----------------------
9032 -- We wish to avoid deep recursion, because concatenations are often
9033 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
9034 -- operands nonrecursively until we find something that is not a simple
9035 -- concatenation (A in this case). We resolve that, and then walk back
9036 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
9037 -- to do the rest of the work at each level. The Parent pointers allow
9038 -- us to avoid recursion, and thus avoid running out of memory. See also
9039 -- Sem_Ch4.Analyze_Concatenation, where a similar approach is used.
9044 begin
9045 -- The following code is equivalent to:
9047 -- Resolve_Op_Concat_First (NN, Typ);
9048 -- Resolve_Op_Concat_Arg (N, ...);
9049 -- Resolve_Op_Concat_Rest (N, Typ);
9051 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
9052 -- operand is a concatenation.
9054 -- Walk down left operands
9056 loop
9065 -- Now (given the above example) NN is A&B and Op1 is A
9067 -- First resolve Op1 ...
9071 -- ... then walk NN back up until we reach N (where we started), calling
9072 -- Resolve_Op_Concat_Rest along the way.
9074 loop
9081 Check_SPARK_05_Restriction
9086 ---------------------------
9087 -- Resolve_Op_Concat_Arg --
9088 ---------------------------
9090 procedure Resolve_Op_Concat_Arg
9095 is
9099 begin
9101 if Is_Comp
9105 then
9107 else
9111 -- If both Array & Array and Array & Component are visible, there is a
9112 -- potential ambiguity that must be reported.
9117 then
9121 -- If the operation is user-defined and not overloaded use its
9122 -- profile. The operation may be a renaming, in which case it has
9123 -- been rewritten, and we want the original profile.
9128 then
9130 Etype
9134 -- Otherwise an aggregate may match both the array type and the
9135 -- component type.
9137 else
9142 else
9146 then
9147 declare
9152 begin
9157 -- Special-case the error message when the overloading is
9158 -- caused by a function that yields an array and can be
9159 -- called without parameters.
9164 Error_Msg_NE
9166 Error_Msg_NE
9170 else
9178 or else
9180 then
9181 Error_Msg_N -- CODEFIX
9199 else
9204 else
9208 -- Concatenation is restricted in SPARK: each operand must be either a
9209 -- string literal, the name of a string constant, a static character or
9210 -- string expression, or another concatenation. Arg cannot be a
9211 -- concatenation here as callers of Resolve_Op_Concat_Arg call it
9212 -- separately on each final operand, past concatenation operations.
9216 Check_SPARK_05_Restriction
9224 then
9225 Check_SPARK_05_Restriction
9229 -- Do not issue error on an operand that is neither a character nor a
9230 -- string, as the error is issued in Resolve_Op_Concat.
9232 else
9239 -----------------------------
9240 -- Resolve_Op_Concat_First --
9241 -----------------------------
9248 begin
9249 -- The parser folds an enormous sequence of concatenations of string
9250 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
9251 -- in the right operand. If the expression resolves to a predefined "&"
9252 -- operator, all is well. Otherwise, the parser's folding is wrong, so
9253 -- we give an error. See P_Simple_Expression in Par.Ch4.
9258 then
9273 ----------------------------
9274 -- Resolve_Op_Concat_Rest --
9275 ----------------------------
9281 begin
9290 -- If this is not a static concatenation, but the result is a string
9291 -- type (and not an array of strings) ensure that static string operands
9292 -- have their subtypes properly constructed.
9296 then
9302 ----------------------
9303 -- Resolve_Op_Expon --
9304 ----------------------
9309 begin
9310 -- Catch attempts to do fixed-point exponentiation with universal
9311 -- operands, which is a case where the illegality is not caught during
9312 -- normal operator analysis. This is not done in preanalysis mode
9313 -- since the tree is not fully decorated during preanalysis.
9324 then
9334 then
9341 then
9345 -- We do the resolution using the base type, because intermediate values
9346 -- in expressions are always of the base type, not a subtype of it.
9351 -- For integer types, right argument must be in Natural range
9366 -- Evaluate the exponentiation operator for dimensioned type
9369 else
9373 -- Set overflow checking bit. Much cleverer code needed here eventually
9374 -- and perhaps the Resolve routines should be separated for the various
9375 -- arithmetic operations, since they will need different processing. ???
9384 --------------------
9385 -- Resolve_Op_Not --
9386 --------------------
9392 -- This function determines if the parent node is a boolean operator or
9393 -- operation (comparison op, membership test, or short circuit form) and
9394 -- the not in question is the left operand of this operation. Note that
9395 -- if the not is in parens, then false is returned.
9397 -----------------------
9398 -- Parent_Is_Boolean --
9399 -----------------------
9402 begin
9406 else
9408 when N_And_Then
9409 | N_In
9410 | N_Not_In
9411 | N_Op_And
9412 | N_Op_Eq
9413 | N_Op_Ge
9414 | N_Op_Gt
9415 | N_Op_Le
9416 | N_Op_Lt
9417 | N_Op_Ne
9418 | N_Op_Or
9419 | N_Op_Xor
9420 | N_Or_Else
9421 =>
9430 -- Start of processing for Resolve_Op_Not
9432 begin
9433 -- Predefined operations on scalar types yield the base type. On the
9434 -- other hand, logical operations on arrays yield the type of the
9435 -- arguments (and the context).
9439 else
9443 -- Straightforward case of incorrect arguments
9450 -- Special case of probable missing parens
9454 Error_Msg_N
9457 else
9458 Error_Msg_N
9465 -- OK resolution of NOT
9467 else
9468 -- Warn if non-boolean types involved. This is a case like not a < b
9469 -- where a and b are modular, where we will get (not a) < b and most
9470 -- likely not (a < b) was intended.
9472 if Warn_On_Questionable_Missing_Parens
9474 and then Parent_Is_Boolean
9475 then
9479 -- Warn on double negation if checking redundant constructs
9481 if Warn_On_Redundant_Constructs
9486 then
9490 -- Complete resolution and evaluation of NOT
9500 -----------------------------
9501 -- Resolve_Operator_Symbol --
9502 -----------------------------
9504 -- Nothing to be done, all resolved already
9510 begin
9514 ----------------------------------
9515 -- Resolve_Qualified_Expression --
9516 ----------------------------------
9524 begin
9527 -- Protect call to Matching_Static_Array_Bounds to avoid costly
9528 -- operation if not needed.
9535 then
9536 Check_SPARK_05_Restriction
9540 -- A qualified expression requires an exact match of the type, class-
9541 -- wide matching is not allowed. However, if the qualifying type is
9542 -- specific and the expression has a class-wide type, it may still be
9543 -- okay, since it can be the result of the expansion of a call to a
9544 -- dispatching function, so we also have to check class-wideness of the
9545 -- type of the expression's original node.
9548 or else
9552 then
9556 -- If the target type is unconstrained, then we reset the type of the
9557 -- result from the type of the expression. For other cases, the actual
9558 -- subtype of the expression is the target type.
9562 then
9569 -- If we still have a qualified expression after the static evaluation,
9570 -- then apply a scalar range check if needed. The reason that we do this
9571 -- after the Eval call is that otherwise, the application of the range
9572 -- check may convert an illegal static expression and result in warning
9573 -- rather than giving an error (e.g Integer'(Integer'Last + 1)).
9579 -- Finally, check whether a predicate applies to the target type. This
9580 -- comes from AI12-0100. As for type conversions, check the enclosing
9581 -- context to prevent an infinite expansion.
9587 or else
9589 then
9592 -- In the case of a qualified expression in an allocator, the check
9593 -- is applied when expanding the allocator, so avoid redundant check.
9597 then
9603 ------------------------------
9604 -- Resolve_Raise_Expression --
9605 ------------------------------
9608 begin
9612 else
9617 -------------------
9618 -- Resolve_Range --
9619 -------------------
9626 -- Returns True if N is of the form X'First .. X'Last where X is the
9627 -- same entity for both attributes.
9629 --------------------
9630 -- First_Last_Ref --
9631 --------------------
9637 begin
9642 then
9643 declare
9646 begin
9650 then
9659 -- Start of processing for Resolve_Range
9661 begin
9664 -- The lower bound should be in Typ. The higher bound can be in Typ's
9665 -- base type if the range is null. It may still be invalid if it is
9666 -- higher than the lower bound. This is checked later in the context in
9667 -- which the range appears.
9672 -- Check for inappropriate range on unordered enumeration type
9676 -- Exclude X'First .. X'Last if X is the same entity for both
9678 and then not First_Last_Ref
9679 then
9681 Error_Msg_NE
9688 -- We have to check the bounds for being within the base range as
9689 -- required for a non-static context. Normally this is automatic and
9690 -- done as part of evaluating expressions, but the N_Range node is an
9691 -- exception, since in GNAT we consider this node to be a subexpression,
9692 -- even though in Ada it is not. The circuit in Sem_Eval could check for
9693 -- this, but that would put the test on the main evaluation path for
9694 -- expressions.
9699 -- Check for an ambiguous range over character literals. This will
9700 -- happen with a membership test involving only literals.
9708 -- If bounds are static, constant-fold them, so size computations are
9709 -- identical between front-end and back-end. Do not perform this
9710 -- transformation while analyzing generic units, as type information
9711 -- would be lost when reanalyzing the constant node in the instance.
9724 --------------------------
9725 -- Resolve_Real_Literal --
9726 --------------------------
9731 begin
9732 -- Special processing for fixed-point literals to make sure that the
9733 -- value is an exact multiple of small where this is required. We skip
9734 -- this for the universal real case, and also for generic types.
9740 then
9741 declare
9748 begin
9749 -- Case of literal is not an exact multiple of the Small
9753 -- For a source program literal for a decimal fixed-point type,
9754 -- this is statically illegal (RM 4.9(36)).
9759 then
9763 -- Generate a warning if literal from source
9766 and then Warn_On_Bad_Fixed_Value
9767 then
9768 Error_Msg_N
9770 N);
9773 -- Replace literal by a value that is the exact representation
9774 -- of a value of the type, i.e. a multiple of the small value,
9775 -- by truncation, since Machine_Rounds is false for all GNAT
9776 -- fixed-point types (RM 4.9(38)).
9786 -- In all cases, set the corresponding integer field
9792 -- Now replace the actual type by the expected type as usual
9798 -----------------------
9799 -- Resolve_Reference --
9800 -----------------------
9805 begin
9806 -- Replace general access with specific type
9814 -- If we are taking the reference of a volatile entity, then treat it as
9815 -- a potential modification of this entity. This is too conservative,
9816 -- but necessary because remove side effects can cause transformations
9817 -- of normal assignments into reference sequences that otherwise fail to
9818 -- notice the modification.
9825 --------------------------------
9826 -- Resolve_Selected_Component --
9827 --------------------------------
9842 -- Check whether this is the initialization of a component within an
9843 -- init proc (by assignment or call to another init proc). If true,
9844 -- there is no need for a discriminant check.
9846 --------------------
9847 -- Init_Component --
9848 --------------------
9851 begin
9852 return Inside_Init_Proc
9858 -- Start of processing for Resolve_Selected_Component
9860 begin
9863 -- Use the context type to select the prefix that has a selector
9864 -- of the correct name and type.
9872 else
9876 -- Locate selected component. For a private prefix the selector
9877 -- can denote a discriminant.
9881 -- The visible components of a class-wide type are those of
9882 -- the root type.
9892 then
9899 else
9903 Error_Msg_N
9908 else
9911 -- There may be an implicit dereference. Retrieve
9912 -- designated record type.
9916 else
9922 -- Resolution chooses the new interpretation.
9923 -- Find the component with the right name.
9928 loop
9945 -- There must be a legal interpretation at this point
9952 else
9953 -- Resolve prefix with its type
9958 -- Generate cross-reference. We needed to wait until full overloading
9959 -- resolution was complete to do this, since otherwise we can't tell if
9960 -- we are an lvalue or not.
9964 else
9968 -- If prefix is an access type, the node will be transformed into an
9969 -- explicit dereference during expansion. The type of the node is the
9970 -- designated type of that of the prefix.
9975 else
9979 -- Set flag for expander if discriminant check required on a component
9980 -- appearing within a variant.
9986 and then
9989 and then not Init_Component
9990 then
9998 -- If the prefix is a record conversion, this may be a renamed
9999 -- discriminant whose bounds differ from those of the original
10000 -- one, so we must ensure that a range check is performed.
10005 then
10009 -- Note: No Eval processing is required, because the prefix is of a
10010 -- record type, or protected type, and neither can possibly be static.
10012 -- If the record type is atomic, and the component is non-atomic, then
10013 -- this is worth a warning, since we have a situation where the access
10014 -- to the component may cause extra read/writes of the atomic array
10015 -- object, or partial word accesses, both of which may be unexpected.
10021 then
10022 Error_Msg_N
10025 Error_Msg_N
10033 -------------------
10034 -- Resolve_Shift --
10035 -------------------
10042 begin
10043 -- We do the resolution using the base type, because intermediate values
10044 -- in expressions always are of the base type, not a subtype of it.
10057 ---------------------------
10058 -- Resolve_Short_Circuit --
10059 ---------------------------
10066 begin
10067 -- Ensure all actions associated with the left operand (e.g.
10068 -- finalization of transient objects) are fully evaluated locally within
10069 -- an expression with actions. This is particularly helpful for coverage
10070 -- analysis. However this should not happen in generics or if option
10071 -- Minimize_Expression_With_Actions is set.
10074 declare
10076 begin
10084 -- Set Comes_From_Source on L to preserve warnings for unset
10085 -- reference.
10094 -- Check for issuing warning for always False assert/check, this happens
10095 -- when assertions are turned off, in which case the pragma Assert/Check
10096 -- was transformed into:
10098 -- if False and then <condition> then ...
10100 -- and we detect this pattern
10102 if Warn_On_Assertion_Failure
10109 then
10110 declare
10113 begin
10114 -- Special handling of Asssert pragma
10118 then
10119 declare
10121 Original_Node
10122 (Expression
10125 begin
10126 -- Don't warn if original condition is explicit False,
10127 -- since obviously the failure is expected in this case.
10131 then
10134 -- Issue warning. We do not want the deletion of the
10135 -- IF/AND-THEN to take this message with it. We achieve this
10136 -- by making sure that the expanded code points to the Sloc
10137 -- of the expression, not the original pragma.
10139 else
10140 -- Note: Use Error_Msg_F here rather than Error_Msg_N.
10141 -- The source location of the expression is not usually
10142 -- the best choice here. For example, it gets located on
10143 -- the last AND keyword in a chain of boolean expressiond
10144 -- AND'ed together. It is best to put the message on the
10145 -- first character of the assertion, which is the effect
10146 -- of the First_Node call here.
10148 Error_Msg_F
10150 Expression
10155 -- Similar processing for Check pragma
10159 then
10160 -- Don't want to warn if original condition is explicit False
10162 declare
10164 Original_Node
10165 (Expression
10167 begin
10170 then
10173 -- Post warning
10175 else
10176 -- Again use Error_Msg_F rather than Error_Msg_N, see
10177 -- comment above for an explanation of why we do this.
10179 Error_Msg_F
10181 Expression
10189 -- Continue with processing of short circuit
10198 -------------------
10199 -- Resolve_Slice --
10200 -------------------
10209 begin
10212 -- Use the context type to select the prefix that yields the correct
10213 -- array type.
10215 declare
10222 begin
10230 then
10238 else
10243 else
10254 else
10264 -- If the prefix is an access to an unconstrained array, we must use
10265 -- the actual subtype of the object to perform the index checks. The
10266 -- object denoted by the prefix is implicit in the node, so we build
10267 -- an explicit representation for it in order to compute the actual
10268 -- subtype.
10273 declare
10277 begin
10288 then
10291 -- If the name is a selected component that depends on discriminants,
10292 -- build an actual subtype for it. This can happen only when the name
10293 -- itself is overloaded; otherwise the actual subtype is created when
10294 -- the selected component is analyzed.
10297 and then Full_Analysis
10299 then
10300 declare
10303 begin
10308 -- Maybe this should just be "else", instead of checking for the
10309 -- specific case of slice??? This is needed for the case where the
10310 -- prefix is an Image attribute, which gets expanded to a slice, and so
10311 -- has a constrained subtype which we want to use for the slice range
10312 -- check applied below (the range check won't get done if the
10313 -- unconstrained subtype of the 'Image is used).
10319 -- Obtain the type of the array index
10323 else
10327 -- If name was overloaded, set slice type correctly now
10331 -- Handle the generation of a range check that compares the array index
10332 -- against the discrete_range. The check is not applied to internally
10333 -- built nodes associated with the expansion of dispatch tables. Check
10334 -- that Ada.Tags has already been loaded to avoid extra dependencies on
10335 -- the unit.
10337 if Tagged_Type_Expansion
10343 then
10346 -- The discrete_range is specified by a subtype indication. Create a
10347 -- shallow copy and inherit the type, parent and source location from
10348 -- the discrete_range. This ensures that the range check is inserted
10349 -- relative to the slice and that the runtime exception points to the
10350 -- proper construct.
10359 -- The discrete_range is a regular range. Resolve the bounds and remove
10360 -- their side effects.
10362 else
10379 -- Check bad use of type with predicates
10381 declare
10384 begin
10387 then
10389 else
10394 Bad_Predicated_Subtype_Use
10399 -- Otherwise here is where we check suspicious indexes
10410 ----------------------------
10411 -- Resolve_String_Literal --
10412 ----------------------------
10423 begin
10424 -- For a string appearing in a concatenation, defer creation of the
10425 -- string_literal_subtype until the end of the resolution of the
10426 -- concatenation, because the literal may be constant-folded away. This
10427 -- is a useful optimization for long concatenation expressions.
10429 -- If the string is an aggregate built for a single character (which
10430 -- happens in a non-static context) or a is null string to which special
10431 -- checks may apply, we build the subtype. Wide strings must also get a
10432 -- string subtype if they come from a one character aggregate. Strings
10433 -- generated by attributes might be static, but it is often hard to
10434 -- determine whether the enclosing context is static, so we generate
10435 -- subtypes for them as well, thus losing some rarer optimizations ???
10436 -- Same for strings that come from a static conversion.
10438 Need_Check :=
10447 -- If the resolving type is itself a string literal subtype, we can just
10448 -- reuse it, since there is no point in creating another.
10454 and then not Need_Check
10456 N_Attribute_Reference,
10457 N_Qualified_Expression,
10458 N_Type_Conversion)
10459 then
10462 -- Do not generate a string literal subtype for the default expression
10463 -- of a formal parameter in GNATprove mode. This is because the string
10464 -- subtype is associated with the freezing actions of the subprogram,
10465 -- however freezing is disabled in GNATprove mode and as a result the
10466 -- subtype is unavailable.
10468 elsif GNATprove_Mode
10470 then
10473 -- Otherwise we must create a string literal subtype. Note that the
10474 -- whole idea of string literal subtypes is simply to avoid the need
10475 -- for building a full fledged array subtype for each literal.
10477 else
10483 or else Need_Check
10484 then
10491 then
10497 -- The validity of a null string has been checked in the call to
10498 -- Eval_String_Literal.
10503 -- Always accept string literal with component type Any_Character, which
10504 -- occurs in error situations and in comparisons of literals, both of
10505 -- which should accept all literals.
10510 -- If the type is bit-packed, then we always transform the string
10511 -- literal into a full fledged aggregate.
10516 -- Deal with cases of Wide_Wide_String, Wide_String, and String
10518 else
10519 -- For Standard.Wide_Wide_String, or any other type whose component
10520 -- type is Standard.Wide_Wide_Character, we know that all the
10521 -- characters in the string must be acceptable, since the parser
10522 -- accepted the characters as valid character literals.
10527 -- For the case of Standard.String, or any other type whose component
10528 -- type is Standard.Character, we must make sure that there are no
10529 -- wide characters in the string, i.e. that it is entirely composed
10530 -- of characters in range of type Character.
10532 -- If the string literal is the result of a static concatenation, the
10533 -- test has already been performed on the components, and need not be
10534 -- repeated.
10538 then
10542 -- If we are out of range, post error. This is one of the
10543 -- very few places that we place the flag in the middle of
10544 -- a token, right under the offending wide character. Not
10545 -- quite clear if this is right wrt wide character encoding
10546 -- sequences, but it's only an error message.
10548 Error_Msg
10555 -- For the case of Standard.Wide_String, or any other type whose
10556 -- component type is Standard.Wide_Character, we must make sure that
10557 -- there are no wide characters in the string, i.e. that it is
10558 -- entirely composed of characters in range of type Wide_Character.
10560 -- If the string literal is the result of a static concatenation,
10561 -- the test has already been performed on the components, and need
10562 -- not be repeated.
10566 then
10570 -- If we are out of range, post error. This is one of the
10571 -- very few places that we place the flag in the middle of
10572 -- a token, right under the offending wide character.
10574 -- This is not quite right, because characters in general
10575 -- will take more than one character position ???
10577 Error_Msg
10584 -- If the root type is not a standard character, then we will convert
10585 -- the string into an aggregate and will let the aggregate code do
10586 -- the checking. Standard Wide_Wide_Character is also OK here.
10588 else
10592 -- See if the component type of the array corresponding to the string
10593 -- has compile time known bounds. If yes we can directly check
10594 -- whether the evaluation of the string will raise constraint error.
10595 -- Otherwise we need to transform the string literal into the
10596 -- corresponding character aggregate and let the aggregate code do
10597 -- the checking.
10601 -- Check for the case of full range, where we are definitely OK
10607 -- Here the range is not the complete base type range, so check
10609 declare
10617 begin
10620 then
10626 then
10627 Apply_Compile_Time_Constraint_Error
10629 CE_Range_Check_Failed,
10640 -- If we got here we meed to transform the string literal into the
10641 -- equivalent qualified positional array aggregate. This is rather
10642 -- heavy artillery for this situation, but it is hard work to avoid.
10644 declare
10649 begin
10650 -- Build the character literals, we give them source locations that
10651 -- correspond to the string positions, which is a bit tricky given
10652 -- the possible presence of wide character escape sequences.
10666 -- Should we have a call to Skip_Wide here ???
10668 -- ??? else
10669 -- Skip_Wide (P);
10677 Expression =>
10684 -------------------------
10685 -- Resolve_Target_Name --
10686 -------------------------
10689 begin
10693 -----------------------------
10694 -- Resolve_Type_Conversion --
10695 -----------------------------
10707 -- Set to False to suppress cases where we want to suppress the test
10708 -- for redundancy to avoid possible false positives on this warning.
10710 begin
10711 if not Conv_OK
10713 then
10717 -- If the Operand Etype is Universal_Fixed, then the conversion is
10718 -- never redundant. We need this check because by the time we have
10719 -- finished the rather complex transformation, the conversion looks
10720 -- redundant when it is not.
10725 -- If the operand is marked as Any_Fixed, then special processing is
10726 -- required. This is also a case where we suppress the test for a
10727 -- redundant conversion, since most certainly it is not redundant.
10732 -- Mixed-mode operation involving a literal. Context must be a fixed
10733 -- type which is applied to the literal subsequently.
10735 -- Multiplication and division involving two fixed type operands must
10736 -- yield a universal real because the result is computed in arbitrary
10737 -- precision.
10743 then
10749 or else
10751 then
10752 -- Return if expression is ambiguous
10757 -- If nothing else, the available fixed type is Duration
10759 else
10763 -- Resolve the real operand with largest available precision
10767 else
10773 -- If the operand is a literal (it could be a non-static and
10774 -- illegal exponentiation) check whether the use of Duration
10775 -- is potentially inaccurate.
10780 then
10781 Error_Msg_N
10784 Error_Msg_N
10791 then
10794 else
10803 -- In SPARK, a type conversion between array types should be restricted
10804 -- to types which have matching static bounds.
10806 -- Protect call to Matching_Static_Array_Bounds to avoid costly
10807 -- operation if not needed.
10814 then
10815 Check_SPARK_05_Restriction
10819 -- In formal mode, the operand of an ancestor type conversion must be an
10820 -- object (not an expression).
10828 then
10834 -- Note: we do the Eval_Type_Conversion call before applying the
10835 -- required checks for a subtype conversion. This is important, since
10836 -- both are prepared under certain circumstances to change the type
10837 -- conversion to a constraint error node, but in the case of
10838 -- Eval_Type_Conversion this may reflect an illegality in the static
10839 -- case, and we would miss the illegality (getting only a warning
10840 -- message), if we applied the type conversion checks first.
10844 -- Even when evaluation is not possible, we may be able to simplify the
10845 -- conversion or its expression. This needs to be done before applying
10846 -- checks, since otherwise the checks may use the original expression
10847 -- and defeat the simplifications. This is specifically the case for
10848 -- elimination of the floating-point Truncation attribute in
10849 -- float-to-int conversions.
10853 -- If after evaluation we still have a type conversion, then we may need
10854 -- to apply checks required for a subtype conversion.
10856 -- Skip these type conversion checks if universal fixed operands
10857 -- operands involved, since range checks are handled separately for
10858 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
10864 then
10868 -- Issue warning for conversion of simple object to its own type. We
10869 -- have to test the original nodes, since they may have been rewritten
10870 -- by various optimizations.
10874 -- Here we test for a redundant conversion if the warning mode is
10875 -- active (and was not locally reset), and we have a type conversion
10876 -- from source not appearing in a generic instance.
10878 if Test_Redundant
10881 and then not In_Instance
10882 then
10886 -- If the node is part of a larger expression, the Target_Type
10887 -- may not be the original type of the node if the context is a
10888 -- condition. Recover original type to see if conversion is needed.
10892 then
10896 -- If we have an entity name, then give the warning if the entity
10897 -- is the right type, or if it is a loop parameter covered by the
10898 -- original type (that's needed because loop parameters have an
10899 -- odd subtype coming from the bounds).
10902 and then
10904 or else
10908 -- If not an entity, then type of expression must match
10911 then
10912 -- One more check, do not give warning if the analyzed conversion
10913 -- has an expression with non-static bounds, and the bounds of the
10914 -- target are static. This avoids junk warnings in cases where the
10915 -- conversion is necessary to establish staticness, for example in
10916 -- a case statement.
10920 then
10923 -- Finally, if this type conversion occurs in a context requiring
10924 -- a prefix, and the expression is a qualified expression then the
10925 -- type conversion is not redundant, since a qualified expression
10926 -- is not a prefix, whereas a type conversion is. For example, "X
10927 -- := T'(Funx(...)).Y;" is illegal because a selected component
10928 -- requires a prefix, but a type conversion makes it legal: "X :=
10929 -- T(T'(Funx(...))).Y;"
10931 -- In Ada 2012, a qualified expression is a name, so this idiom is
10932 -- no longer needed, but we still suppress the warning because it
10933 -- seems unfriendly for warnings to pop up when you switch to the
10934 -- newer language version.
10938 N_Indexed_Component,
10939 N_Selected_Component,
10940 N_Slice,
10941 N_Explicit_Dereference)
10942 then
10945 -- Never warn on conversion to Long_Long_Integer'Base since
10946 -- that is most likely an artifact of the extended overflow
10947 -- checking and comes from complex expanded code.
10952 -- Here we give the redundant conversion warning. If it is an
10953 -- entity, give the name of the entity in the message. If not,
10954 -- just mention the expression.
10956 -- Shoudn't we test Warn_On_Redundant_Constructs here ???
10958 else
10961 Error_Msg_NE -- CODEFIX
10964 else
10965 Error_Msg_NE
10973 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
10974 -- No need to perform any interface conversion if the type of the
10975 -- expression coincides with the target type.
10978 and then Expander_Active
10980 then
10981 declare
10985 begin
10986 -- If the type of the operand is a limited view, use nonlimited
10987 -- view when available. If it is a class-wide type, recover the
10988 -- class-wide type of the nonlimited view.
10992 then
11008 -- Conversion from interface type
11012 -- Ada 2005 (AI-217): Handle entities from limited views
11016 Error_Msg_NE -- CODEFIX
11019 Error_Msg_N
11021 N);
11024 and then not
11027 then
11029 Error_Msg_NE -- CODEFIX
11032 Error_Msg_N
11034 N);
11036 else
11040 -- Conversion to interface type
11044 -- Handle subtypes
11051 or else Interface_Present_In_Ancestor
11054 then
11056 else
11059 Error_Msg_N
11067 -- Ada 2012: once the type conversion is resolved, check whether the
11068 -- operand statisfies the static predicate of the target type.
11074 -- If at this stage we have a real to integer conversion, make sure that
11075 -- the Do_Range_Check flag is set, because such conversions in general
11076 -- need a range check. We only need this if expansion is off.
11077 -- In GNATprove mode, we only do that when converting from fixed-point
11078 -- (as floating-point to integer conversions are now handled in
11079 -- GNATprove mode).
11082 and then not Expander_Active
11087 then
11091 -- Generating C code a type conversion of an access to constrained
11092 -- array type to access to unconstrained array type involves building
11093 -- a fat pointer which in general cannot be generated on the fly. We
11094 -- remove side effects in order to store the result of the conversion
11095 -- into a temporary.
11097 if Modify_Tree_For_C
11104 then
11109 ----------------------
11110 -- Resolve_Unary_Op --
11111 ----------------------
11120 begin
11123 Check_SPARK_05_Restriction
11127 -- Deal with intrinsic unary operators
11133 then
11138 -- Deal with universal cases
11141 or else
11143 then
11150 -- Generate warning for expressions like abs (x mod 2)
11152 if Warn_On_Redundant_Constructs
11154 then
11158 Error_Msg_N -- CODEFIX
11163 -- Deal with reference generation
11170 -- Set overflow checking bit. Much cleverer code needed here eventually
11171 -- and perhaps the Resolve routines should be separated for the various
11172 -- arithmetic operations, since they will need different processing ???
11180 -- Generate warning for expressions like -5 mod 3 for integers. No need
11181 -- to worry in the floating-point case, since parens do not affect the
11182 -- result so there is no point in giving in a warning.
11184 declare
11193 begin
11194 if Warn_On_Questionable_Missing_Parens
11198 then
11201 -- We are looking for cases where the right operand is not
11202 -- parenthesized, and is a binary operator, multiply, divide, or
11203 -- mod. These are the cases where the grouping can affect results.
11207 then
11208 -- For mod, we always give the warning, since the value is
11209 -- affected by the parenthesization (e.g. (-5) mod 315 /=
11210 -- -(5 mod 315)). But for the other cases, the only concern is
11211 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
11212 -- overflows, but (-2) * 64 does not). So we try to give the
11213 -- message only when overflow is possible.
11217 then
11222 else
11228 else
11232 -- Note that the test below is deliberately excluding the
11233 -- largest negative number, since that is a potentially
11234 -- troublesome case (e.g. -2 * x, where the result is the
11235 -- largest negative integer has an overflow with 2 * x).
11242 -- For the multiplication case, the only case we have to worry
11243 -- about is when (-a)*b is exactly the largest negative number
11244 -- so that -(a*b) can cause overflow. This can only happen if
11245 -- a is a power of 2, and more generally if any operand is a
11246 -- constant that is not a power of 2, then the parentheses
11247 -- cannot affect whether overflow occurs. We only bother to
11248 -- test the left most operand
11250 -- Loop looking at left operands for one that has known value
11257 -- Operand value of 0 or 1 skips warning
11262 -- Otherwise check power of 2, if power of 2, warn, if
11263 -- anything else, skip warning.
11265 else
11269 else
11278 -- Keep looking at left operands
11283 -- For rem or "/" we can only have a problematic situation
11284 -- if the divisor has a value of minus one or one. Otherwise
11285 -- overflow is impossible (divisor > 1) or we have a case of
11286 -- division by zero in any case.
11291 then
11295 -- If we fall through warning should be issued
11297 -- Shouldn't we test Warn_On_Questionable_Missing_Parens ???
11299 Error_Msg_N
11306 ----------------------------------
11307 -- Resolve_Unchecked_Expression --
11308 ----------------------------------
11310 procedure Resolve_Unchecked_Expression
11313 is
11314 begin
11319 ---------------------------------------
11320 -- Resolve_Unchecked_Type_Conversion --
11321 ---------------------------------------
11323 procedure Resolve_Unchecked_Type_Conversion
11326 is
11332 begin
11333 -- Resolve operand using its own type
11337 -- In an inlined context, the unchecked conversion may be applied
11338 -- to a literal, in which case its type is the type of the context.
11339 -- (In other contexts conversions cannot apply to literals).
11341 if In_Inlined_Body
11345 then
11353 ------------------------------
11354 -- Rewrite_Operator_As_Call --
11355 ------------------------------
11362 begin
11369 New_N :=
11380 ------------------------------
11381 -- Rewrite_Renamed_Operator --
11382 ------------------------------
11384 procedure Rewrite_Renamed_Operator
11388 is
11393 begin
11394 -- Do not perform this transformation within a pre/postcondition,
11395 -- because the expression will be re-analyzed, and the transformation
11396 -- might affect the visibility of the operator, e.g. in an instance.
11397 -- Note that fully analyzed and expanded pre/postconditions appear as
11398 -- pragma Check equivalents.
11404 -- Rewrite the operator node using the real operator, not its renaming.
11405 -- Exclude user-defined intrinsic operations of the same name, which are
11406 -- treated separately and rewritten as calls.
11415 -- Indicate that both the original entity and its renaming are
11416 -- referenced at this point.
11427 -- If the context type is private, add the appropriate conversions so
11428 -- that the operator is applied to the full view. This is done in the
11429 -- routines that resolve intrinsic operators.
11433 when N_Op_Add
11434 | N_Op_Divide
11435 | N_Op_Expon
11436 | N_Op_Mod
11437 | N_Op_Multiply
11438 | N_Op_Rem
11439 | N_Op_Subtract
11440 =>
11443 when N_Op_Abs
11444 | N_Op_Minus
11445 | N_Op_Plus
11446 =>
11456 -- Operator renames a user-defined operator of the same name. Use the
11457 -- original operator in the node, which is the one Gigi knows about.
11464 -----------------------
11465 -- Set_Slice_Subtype --
11466 -----------------------
11468 -- Build an implicit subtype declaration to represent the type delivered by
11469 -- the slice. This is an abbreviated version of an array subtype. We define
11470 -- an index subtype for the slice, using either the subtype name or the
11471 -- discrete range of the slice. To be consistent with index usage elsewhere
11472 -- we create a list header to hold the single index. This list is not
11473 -- otherwise attached to the syntax tree.
11484 begin
11490 else
11491 -- We force the evaluation of a range. This is definitely needed in
11492 -- the renamed case, and seems safer to do unconditionally. Note in
11493 -- any case that since we will create and insert an Itype referring
11494 -- to this range, we must make sure any side effect removal actions
11495 -- are inserted before the Itype definition.
11501 -- If the discrete range is given by a subtype indication, the
11502 -- type of the slice is the base of the subtype mark.
11505 declare
11507 begin
11516 -- Take a new copy of Drange (where bounds have been rewritten to
11517 -- reference side-effect-free names). Using a separate tree ensures
11518 -- that further expansion (e.g. while rewriting a slice assignment
11519 -- into a FOR loop) does not attempt to remove side effects on the
11520 -- bounds again (which would cause the bounds in the index subtype
11521 -- definition to refer to temporaries before they are defined) (the
11522 -- reason is that some names are considered side effect free here
11523 -- for the subtype, but not in the context of a loop iteration
11524 -- scheme).
11545 -- The Etype of the existing Slice node is reset to this slice subtype.
11546 -- Its bounds are obtained from its first index.
11550 -- For bit-packed slice subtypes, freeze immediately (except in the case
11551 -- of being in a "spec expression" where we never freeze when we first
11552 -- see the expression).
11557 -- For all other cases insert an itype reference in the slice's actions
11558 -- so that the itype is frozen at the proper place in the tree (i.e. at
11559 -- the point where actions for the slice are analyzed). Note that this
11560 -- is different from freezing the itype immediately, which might be
11561 -- premature (e.g. if the slice is within a transient scope). This needs
11562 -- to be done only if expansion is enabled.
11569 --------------------------------
11570 -- Set_String_Literal_Subtype --
11571 --------------------------------
11579 begin
11591 -- The low bound is set from the low bound of the corresponding index
11592 -- type. Note that we do not store the high bound in the string literal
11593 -- subtype, but it can be deduced if necessary from the length and the
11594 -- low bound.
11599 -- If the lower bound is not static we create a range for the string
11600 -- literal, using the index type and the known length of the literal.
11601 -- The index type is not necessarily Positive, so the upper bound is
11602 -- computed as T'Val (T'Pos (Low_Bound) + L - 1).
11604 else
11605 declare
11611 Prefix =>
11615 Left_Opnd =>
11618 Prefix =>
11620 Expressions =>
11622 Right_Opnd =>
11631 begin
11633 Set_String_Literal_Low_Bound
11636 else
11637 -- If the index type is an enumeration type, build bounds
11638 -- expression with attributes.
11640 Set_String_Literal_Low_Bound
11644 Prefix =>
11651 -- Build bona fide subtype for the string, and wrap it in an
11652 -- unchecked conversion, because the backend expects the
11653 -- String_Literal_Subtype to have a static lower bound.
11655 Index_Subtype :=
11662 -- In the context, the Index_Type may already have a constraint,
11663 -- so use common base type on string subtype. The base type may
11664 -- be used when generating attributes of the string, for example
11665 -- in the context of a slice assignment.
11690 ------------------------------
11691 -- Simplify_Type_Conversion --
11692 ------------------------------
11695 begin
11697 declare
11702 begin
11703 -- Special processing if the conversion is the expression of a
11704 -- Rounding or Truncation attribute reference. In this case we
11705 -- replace:
11707 -- ityp (ftyp'Rounding (x)) or ityp (ftyp'Truncation (x))
11709 -- by
11711 -- ityp (x)
11713 -- with the Float_Truncate flag set to False or True respectively,
11714 -- which is more efficient.
11717 and then
11723 Name_Truncation)
11724 then
11725 declare
11728 begin
11738 -----------------------------
11739 -- Unique_Fixed_Point_Type --
11740 -----------------------------
11744 -- Give error messages for true ambiguity. Messages are posted on node
11745 -- N, and entities T1, T2 are the possible interpretations.
11747 -----------------------
11748 -- Fixed_Point_Error --
11749 -----------------------
11752 begin
11758 -- Local variables
11766 -- Start of processing for Unique_Fixed_Point_Type
11768 begin
11769 -- The operations on Duration are visible, so Duration is always a
11770 -- possible interpretation.
11774 -- Look for fixed-point types in enclosing scopes
11783 then
11787 else
11798 -- Look for visible fixed type declarations in the context
11809 then
11813 else
11828 else
11829 -- When the context is a type conversion, issue the warning on the
11830 -- expression of the conversion because it is the actual operation.
11834 else
11838 Error_Msg_NE
11845 ----------------------
11846 -- Valid_Conversion --
11847 ----------------------
11849 function Valid_Conversion
11854 is
11859 function Conversion_Check
11862 -- Little routine to post Msg if Valid is False, returns Valid value
11865 -- If Report_Errs, then calls Errout.Error_Msg_N with its arguments
11867 procedure Conversion_Error_NE
11871 -- If Report_Errs, then calls Errout.Error_Msg_NE with its arguments
11874 -- Return True if expression is within an instance but is not in one of
11875 -- the actuals of the instantiation. Type conversions within an instance
11876 -- are not rechecked because type visbility may lead to spurious errors,
11877 -- but conversions in an actual for a formal object must be checked.
11879 function Valid_Tagged_Conversion
11882 -- Specifically test for validity of tagged conversions
11885 -- Check index and component conformance, and accessibility levels if
11886 -- the component types are anonymous access types (Ada 2005).
11888 ----------------------
11889 -- Conversion_Check --
11890 ----------------------
11892 function Conversion_Check
11895 is
11896 begin
11897 if not Valid
11899 -- A generic unit has already been analyzed and we have verified
11900 -- that a particular conversion is OK in that context. Since the
11901 -- instance is reanalyzed without relying on the relationships
11902 -- established during the analysis of the generic, it is possible
11903 -- to end up with inconsistent views of private types. Do not emit
11904 -- the error message in such cases. The rest of the machinery in
11905 -- Valid_Conversion still ensures the proper compatibility of
11906 -- target and operand types.
11908 and then not In_Instance_Code
11909 then
11916 ------------------------
11917 -- Conversion_Error_N --
11918 ------------------------
11921 begin
11927 -------------------------
11928 -- Conversion_Error_NE --
11929 -------------------------
11931 procedure Conversion_Error_NE
11935 is
11936 begin
11942 ----------------------
11943 -- In_Instance_Code --
11944 ----------------------
11949 begin
11953 else
11957 -- The expression is part of an actual object if it appears in
11958 -- the generated object declaration in the instance.
11962 then
11965 else
11966 exit when
11975 -- Otherwise the expression appears within the instantiated unit
11981 ----------------------------
11982 -- Valid_Array_Conversion --
11983 ----------------------------
12000 begin
12001 -- Error if wrong number of dimensions
12003 if
12005 then
12006 Conversion_Error_N
12010 -- Number of dimensions matches
12012 else
12013 -- Loop through indexes of the two arrays
12021 -- Error if index types are incompatible
12027 then
12028 Conversion_Error_N
12030 Operand);
12038 -- If component types have same base type, all set
12043 -- Here if base types of components are not the same. The only
12044 -- time this is allowed is if we have anonymous access types.
12046 -- The conversion of arrays of anonymous access types can lead
12047 -- to dangling pointers. AI-392 formalizes the accessibility
12048 -- checks that must be applied to such conversions to prevent
12049 -- out-of-scope references.
12051 elsif Ekind_In
12053 E_Anonymous_Access_Subprogram_Type)
12055 and then
12057 then
12060 then
12063 Conversion_Error_N
12073 -- Conversion not allowed because of accessibility levels
12075 else
12076 Conversion_Error_N
12082 else
12086 -- All other cases where component base types do not match
12088 else
12089 Conversion_Error_N
12091 Operand);
12095 -- Check that component subtypes statically match. For numeric
12096 -- types this means that both must be either constrained or
12097 -- unconstrained. For enumeration types the bounds must match.
12098 -- All of this is checked in Subtypes_Statically_Match.
12100 if not Subtypes_Statically_Match
12102 then
12103 Conversion_Error_N
12112 -----------------------------
12113 -- Valid_Tagged_Conversion --
12114 -----------------------------
12116 function Valid_Tagged_Conversion
12119 is
12120 begin
12121 -- Upward conversions are allowed (RM 4.6(22))
12125 then
12128 -- Downward conversion are allowed if the operand is class-wide
12129 -- (RM 4.6(23)).
12133 then
12138 then
12139 return
12143 -- Ada 2005 (AI-251): The conversion to/from interface types is
12144 -- always valid. The types involved may be class-wide (sub)types.
12148 then
12151 -- If the operand is a class-wide type obtained through a limited_
12152 -- with clause, and the context includes the nonlimited view, use
12153 -- it to determine whether the conversion is legal.
12159 then
12164 then
12167 else
12168 Conversion_Error_NE
12175 -- Start of processing for Valid_Conversion
12177 begin
12181 declare
12189 begin
12190 -- Remove procedure calls, which syntactically cannot appear in
12191 -- this context, but which cannot be removed by type checking,
12192 -- because the context does not impose a type.
12194 -- The node may be labelled overloaded, but still contain only one
12195 -- interpretation because others were discarded earlier. If this
12196 -- is the case, retain the single interpretation if legal.
12204 then
12205 -- More than one candidate interpretation is available
12213 -- When compiling for a system where Address is of a visible
12214 -- integer type, spurious ambiguities can be produced when
12215 -- arithmetic operations have a literal operand and return
12216 -- System.Address or a descendant of it. These ambiguities
12217 -- are usually resolved by the context, but for conversions
12218 -- there is no context type and the removal of the spurious
12219 -- operations must be done explicitly here.
12221 if not Address_Is_Private
12223 then
12248 Conversion_Error_N
12251 -- If the interpretation involves a standard operator, use
12252 -- the location of the type, which may be user-defined.
12256 else
12260 Conversion_Error_N -- CODEFIX
12265 else
12269 Conversion_Error_N -- CODEFIX
12281 -- Deal with conversion of integer type to address if the pragma
12282 -- Allow_Integer_Address is in effect. We convert the conversion to
12283 -- an unchecked conversion in this case and we are all done.
12291 -- If we are within a child unit, check whether the type of the
12292 -- expression has an ancestor in a parent unit, in which case it
12293 -- belongs to its derivation class even if the ancestor is private.
12294 -- See RM 7.3.1 (5.2/3).
12298 -- Numeric types
12302 -- A universal fixed expression can be converted to any numeric type
12307 -- Also no need to check when in an instance or inlined body, because
12308 -- the legality has been established when the template was analyzed.
12309 -- Furthermore, numeric conversions may occur where only a private
12310 -- view of the operand type is visible at the instantiation point.
12311 -- This results in a spurious error if we check that the operand type
12312 -- is a numeric type.
12314 -- Note: in a previous version of this unit, the following tests were
12315 -- applied only for generated code (Comes_From_Source set to False),
12316 -- but in fact the test is required for source code as well, since
12317 -- this situation can arise in source code.
12322 -- Otherwise we need the conversion check
12324 else
12325 return Conversion_Check
12327 or else
12333 -- Array types
12339 then
12340 Conversion_Error_N
12344 else
12348 -- Ada 2005 (AI-251): Internally generated conversions of access to
12349 -- interface types added to force the displacement of the pointer to
12350 -- reference the corresponding dispatch table.
12355 then
12358 -- Ada 2005 (AI-251): Anonymous access types where target references an
12359 -- interface type.
12363 E_Anonymous_Access_Type)
12365 then
12366 -- Check the static accessibility rule of 4.6(17). Note that the
12367 -- check is not enforced when within an instance body, since the
12368 -- RM requires such cases to be caught at run time.
12370 -- If the operand is a rewriting of an allocator no check is needed
12371 -- because there are no accessibility issues.
12379 then
12380 -- In an instance, this is a run-time check, but one we know
12381 -- will fail, so generate an appropriate warning. The raise
12382 -- will be generated by Expand_N_Type_Conversion.
12386 Conversion_Error_N
12388 Operand);
12391 else
12392 Conversion_Error_N
12394 Operand);
12398 -- Special accessibility checks are needed in the case of access
12399 -- discriminants declared for a limited type.
12403 then
12404 -- When the operand is a selected access discriminant the check
12405 -- needs to be made against the level of the object denoted by
12406 -- the prefix of the selected name (Object_Access_Level handles
12407 -- checking the prefix of the operand for this case).
12412 then
12413 -- In an instance, this is a run-time check, but one we know
12414 -- will fail, so generate an appropriate warning. The raise
12415 -- will be generated by Expand_N_Type_Conversion.
12419 Conversion_Error_N
12424 -- Real error if not in instance body
12426 else
12427 Conversion_Error_N
12434 -- The case of a reference to an access discriminant from
12435 -- within a limited type declaration (which will appear as
12436 -- a discriminal) is always illegal because the level of the
12437 -- discriminant is considered to be deeper than any (nameable)
12438 -- access type.
12442 and then
12445 then
12446 Conversion_Error_N
12448 Operand);
12456 -- General and anonymous access types
12459 E_Anonymous_Access_Type)
12460 and then
12461 Conversion_Check
12463 and then not
12465 E_Access_Protected_Subprogram_Type),
12467 then
12470 then
12471 Conversion_Error_N
12476 -- Check the static accessibility rule of 4.6(17). Note that the
12477 -- check is not enforced when within an instance body, since the RM
12478 -- requires such cases to be caught at run time.
12483 N_Object_Declaration
12484 then
12485 -- Ada 2012 (AI05-0149): Perform legality checking on implicit
12486 -- conversions from an anonymous access type to a named general
12487 -- access type. Such conversions are not allowed in the case of
12488 -- access parameters and stand-alone objects of an anonymous
12489 -- access type. The implicit conversion case is recognized by
12490 -- testing that Comes_From_Source is False and that it's been
12491 -- rewritten. The Comes_From_Source test isn't sufficient because
12492 -- nodes in inlined calls to predefined library routines can have
12493 -- Comes_From_Source set to False. (Is there a better way to test
12494 -- for implicit conversions???)
12501 then
12504 -- Implicit conversions aren't allowed for objects of an
12505 -- anonymous access type, since such objects have nonstatic
12506 -- levels in Ada 2012.
12509 N_Object_Declaration
12510 then
12511 Conversion_Error_N
12516 -- Implicit conversions aren't allowed for anonymous access
12517 -- parameters. The "not Is_Local_Anonymous_Access_Type" test
12518 -- is done to exclude anonymous access results.
12522 N_Function_Specification,
12523 N_Procedure_Specification)
12524 then
12525 Conversion_Error_N
12530 -- This is a case where there's an enclosing object whose
12531 -- to which the "statically deeper than" relationship does
12532 -- not apply (such as an access discriminant selected from
12533 -- a dereference of an access parameter).
12537 then
12538 Conversion_Error_N
12543 -- In other cases, the level of the operand's type must be
12544 -- statically less deep than that of the target type, else
12545 -- implicit conversion is disallowed (by RM12-8.6(27.1/3)).
12549 then
12550 Conversion_Error_N
12559 then
12560 -- In an instance, this is a run-time check, but one we know
12561 -- will fail, so generate an appropriate warning. The raise
12562 -- will be generated by Expand_N_Type_Conversion.
12566 Conversion_Error_N
12568 Operand);
12571 -- If not in an instance body, this is a real error
12573 else
12574 -- Avoid generation of spurious error message
12577 Conversion_Error_N
12579 Operand);
12585 -- Special accessibility checks are needed in the case of access
12586 -- discriminants declared for a limited type.
12590 then
12591 -- When the operand is a selected access discriminant the check
12592 -- needs to be made against the level of the object denoted by
12593 -- the prefix of the selected name (Object_Access_Level handles
12594 -- checking the prefix of the operand for this case).
12599 then
12600 -- In an instance, this is a run-time check, but one we know
12601 -- will fail, so generate an appropriate warning. The raise
12602 -- will be generated by Expand_N_Type_Conversion.
12606 Conversion_Error_N
12611 -- If not in an instance body, this is a real error
12613 else
12614 Conversion_Error_N
12621 -- The case of a reference to an access discriminant from
12622 -- within a limited type declaration (which will appear as
12623 -- a discriminal) is always illegal because the level of the
12624 -- discriminant is considered to be deeper than any (nameable)
12625 -- access type.
12628 and then
12631 then
12632 Conversion_Error_N
12634 Operand);
12640 -- In the presence of limited_with clauses we have to use nonlimited
12641 -- views, if available.
12645 -- Helper function to handle limited views
12647 --------------------------
12648 -- Full_Designated_Type --
12649 --------------------------
12654 begin
12655 -- Handle the limited view of a type
12659 then
12661 else
12666 -- Local Declarations
12674 -- Start of processing for Check_Limited
12676 begin
12680 else
12682 Conversion_Error_NE
12687 -- Ada 2005 AI-384: legality rule is symmetric in both
12688 -- designated types. The conversion is legal (with possible
12689 -- constraint check) if either designated type is
12690 -- unconstrained.
12693 or else
12695 and then
12698 then
12699 -- Special case, if Value_Size has been used to make the
12700 -- sizes different, the conversion is not allowed even
12701 -- though the subtypes statically match.
12706 then
12707 Conversion_Error_NE
12710 Conversion_Error_NE
12715 -- Normal case where conversion is allowed
12717 else
12721 else
12722 Error_Msg_NE
12730 -- Access to subprogram types. If the operand is an access parameter,
12731 -- the type has a deeper accessibility that any master, and cannot be
12732 -- assigned. We must make an exception if the conversion is part of an
12733 -- assignment and the target is the return object of an extended return
12734 -- statement, because in that case the accessibility check takes place
12735 -- after the return.
12739 -- Note: this test of Opnd_Type is there to prevent entering this
12740 -- branch in the case of a remote access to subprogram type, which
12741 -- is internally represented as an E_Record_Type.
12744 then
12748 and then
12752 then
12753 Conversion_Error_N
12755 Operand);
12756 Conversion_Error_N
12759 Operand);
12761 Error_Msg_NE
12766 -- Check that the designated types are subtype conformant
12772 -- Check the static accessibility rule of 4.6(20)
12776 then
12777 Conversion_Error_N
12779 Operand);
12781 -- Check that if the operand type is declared in a generic body,
12782 -- then the target type must be declared within that same body
12783 -- (enforces last sentence of 4.6(20)).
12786 declare
12792 begin
12799 Conversion_Error_N
12808 -- Remote access to subprogram types
12812 then
12813 -- It is valid to convert from one RAS type to another provided
12814 -- that their specification statically match.
12816 -- Note: at this point, remote access to subprogram types have been
12817 -- expanded to their E_Record_Type representation, and we need to
12818 -- go back to the original access type definition using the
12819 -- Corresponding_Remote_Type attribute in order to check that the
12820 -- designated profiles match.
12825 Check_Subtype_Conformant
12828 Old_Id =>
12830 Err_Loc =>
12831 N);
12834 -- If it was legal in the generic, it's legal in the instance
12839 -- If both are tagged types, check legality of view conversions
12842 and then
12844 then
12847 -- Types derived from the same root type are convertible
12852 -- In an instance or an inlined body, there may be inconsistent views of
12853 -- the same type, or of types derived from a common root.
12856 and then
12859 then
12862 -- Special check for common access type error case
12866 then
12868 Conversion_Error_NE -- CODEFIX
12872 -- Here we have a real conversion error
12874 else
12875 Conversion_Error_NE