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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 -- Ensure that the corresponding operator has the same parent as the
1329 -- original call. This guarantees that parent traversals performed by
1330 -- the ABE mechanism succeed.
1334 -- Binary operator
1344 -- Unary operator
1346 else
1352 -- If the operator is denoted by an expanded name, and the prefix is
1353 -- not Standard, but the operator is a predefined one whose scope is
1354 -- Standard, then this is an implicit_operator, inserted as an
1355 -- interpretation by the procedure of the same name. This procedure
1356 -- overestimates the presence of implicit operators, because it does
1357 -- not examine the type of the operands. Verify now that the operand
1358 -- type appears in the given scope. If right operand is universal,
1359 -- check the other operand. In the case of concatenation, either
1360 -- argument can be the component type, so check the type of the result.
1361 -- If both arguments are literals, look for a type of the right kind
1362 -- defined in the given scope. This elaborate nonsense is brought to
1363 -- you courtesy of b33302a. The type itself must be frozen, so we must
1364 -- find the type of the proper class in the given scope.
1366 -- A final wrinkle is the multiplication operator for fixed point types,
1367 -- which is defined in Standard only, and not in the scope of the
1368 -- fixed point type itself.
1373 -- If this is a package renaming, get renamed entity, which will be
1374 -- the scope of the operands if operaton is type-correct.
1380 -- If the entity being called is defined in the given package, it is
1381 -- a renaming of a predefined operator, and known to be legal.
1385 then
1388 -- Visibility does not need to be checked in an instance: if the
1389 -- operator was not visible in the generic it has been diagnosed
1390 -- already, else there is an implicit copy of it in the instance.
1398 then
1403 -- Ada 2005 AI-420: Predefined equality on Universal_Access is
1404 -- available.
1409 then
1412 else
1421 and then Is_Binary
1423 then
1429 -- Verify that the scope contains a type that corresponds to
1430 -- the given literal. Optimize the case where Pack is Standard.
1451 else
1460 else
1469 then
1472 -- If the type is defined elsewhere, and the operator is not
1473 -- defined in the given scope (by a renaming declaration, e.g.)
1474 -- then this is an error as well. If an extension of System is
1475 -- present, and the type may be defined there, Pack must be
1476 -- System itself.
1483 then
1486 else
1492 then
1499 Error_Msg_NE
1504 -- Detect a mismatch between the context type and the result type
1505 -- in the named package, which is otherwise not detected if the
1506 -- operands are universal. Check is only needed if source entity is
1507 -- an operator, not a function that renames an operator.
1514 and then not In_Instance
1515 then
1518 then
1519 -- Already checked above
1523 -- Operator may be defined in an extension of System
1528 then
1531 else
1532 -- Could we use Wrong_Type here??? (this would require setting
1533 -- Etype (N) to the actual type found where Typ was expected).
1544 else
1548 -- If this is a call to a function that renames a predefined equality,
1549 -- the renaming declaration provides a type that must be used to
1550 -- resolve the operands. This must be done now because resolution of
1551 -- the equality node will not resolve any remaining ambiguity, and it
1552 -- assumes that the first operand is not overloaded.
1557 then
1565 -- Do rewrite setting Comes_From_Source on the result if the original
1566 -- call came from source. Although it is not strictly the case that the
1567 -- operator as such comes from the source, logically it corresponds
1568 -- exactly to the function call in the source, so it should be marked
1569 -- this way (e.g. to make sure that validity checks work fine).
1571 declare
1573 begin
1578 -- If this is an arithmetic operator and the result type is private,
1579 -- the operands and the result must be wrapped in conversion to
1580 -- expose the underlying numeric type and expand the proper checks,
1581 -- e.g. on division.
1585 when N_Op_Add
1586 | N_Op_Divide
1587 | N_Op_Expon
1588 | N_Op_Mod
1589 | N_Op_Multiply
1590 | N_Op_Rem
1591 | N_Op_Subtract
1592 =>
1595 when N_Op_Abs
1596 | N_Op_Minus
1597 | N_Op_Plus
1598 =>
1604 else
1608 -- If in ASIS_Mode, propagate operand types to original actuals of
1609 -- function call, which would otherwise not be fully resolved. If
1610 -- the call has already been constant-folded, nothing to do. We
1611 -- relocate the operand nodes rather than copy them, to preserve
1612 -- original_node pointers, given that the operands themselves may
1613 -- have been rewritten. If the call was itself a rewriting of an
1614 -- operator node, nothing to do.
1616 if ASIS_Mode
1619 then
1620 declare
1628 begin
1633 -- If the original call has named associations, replace the
1634 -- explicit actual parameter in the association with the proper
1635 -- resolved operand.
1640 then
1643 else
1648 else
1655 then
1658 else
1663 else
1667 else
1671 else
1681 -------------------
1682 -- Operator_Kind --
1683 -------------------
1685 function Operator_Kind
1688 is
1691 begin
1692 -- Use CASE statement or array???
1729 else
1733 -- Unary operators
1735 else
1744 else
1752 ----------------------------
1753 -- Preanalyze_And_Resolve --
1754 ----------------------------
1759 begin
1763 -- Normally, we suppress all checks for this preanalysis. There is no
1764 -- point in processing them now, since they will be applied properly
1765 -- and in the proper location when the default expressions reanalyzed
1766 -- and reexpanded later on. We will also have more information at that
1767 -- point for possible suppression of individual checks.
1769 -- However, in SPARK mode, most expansion is suppressed, and this
1770 -- later reanalysis and reexpansion may not occur. SPARK mode does
1771 -- require the setting of checking flags for proof purposes, so we
1772 -- do the SPARK preanalysis without suppressing checks.
1774 -- This special handling for SPARK mode is required for example in the
1775 -- case of Ada 2012 constructs such as quantified expressions, which are
1776 -- expanded in two separate steps.
1780 else
1784 Expander_Mode_Restore;
1788 -- Version without context type
1793 begin
1800 Expander_Mode_Restore;
1804 ----------------------------------
1805 -- Replace_Actual_Discriminants --
1806 ----------------------------------
1813 -- Comment needed???
1815 -------------------
1816 -- Process_Discr --
1817 -------------------
1822 begin
1828 then
1844 -- Start of processing for Replace_Actual_Discriminants
1846 begin
1850 -- Allow the replacement of concurrent discriminants in GNATprove even
1851 -- though this is a light expansion activity. Note that generic units
1852 -- are not modified.
1857 else
1873 -------------
1874 -- Resolve --
1875 -------------
1891 -- Determine whether a node comes from a predefined library unit or
1892 -- Standard.
1895 -- Try and fix up a literal so that it matches its expected type. New
1896 -- literals are manufactured if necessary to avoid cascaded errors.
1899 -- Additional diagnostics when an ambiguous call has an ambiguous
1900 -- argument (typically a controlling actual).
1903 -- Called when attempt at resolving current expression fails
1905 ------------------------------------
1906 -- Comes_From_Predefined_Lib_Unit --
1907 -------------------------------------
1910 begin
1911 return
1915 --------------------
1916 -- Patch_Up_Value --
1917 --------------------
1920 begin
1937 then
1942 Char_Literal_Value =>
1958 -------------------------------
1959 -- Report_Ambiguous_Argument --
1960 -------------------------------
1967 begin
1971 then
1974 -- Could use comments on what is going on here???
1982 else
1991 -----------------------
1992 -- Resolution_Failed --
1993 -----------------------
1996 begin
1999 -- Set the type to the desired one to minimize cascaded errors. Note
2000 -- that this is an approximation and does not work in all cases.
2007 -- The caller will return without calling the expander, so we need
2008 -- to set the analyzed flag. Note that it is fine to set Analyzed
2009 -- to True even if we are in the middle of a shallow analysis,
2010 -- (see the spec of sem for more details) since this is an error
2011 -- situation anyway, and there is no point in repeating the
2012 -- analysis later (indeed it won't work to repeat it later, since
2013 -- we haven't got a clear resolution of which entity is being
2014 -- referenced.)
2020 -- Start of processing for Resolve
2022 begin
2027 -- Access attribute on remote subprogram cannot be used for a non-remote
2028 -- access-to-subprogram type.
2032 Name_Unrestricted_Access,
2033 Name_Unchecked_Access)
2039 then
2040 Error_Msg_N
2046 -- If the context is a Remote_Access_To_Subprogram, access attributes
2047 -- must be resolved with the corresponding fat pointer. There is no need
2048 -- to check for the attribute name since the return type of an
2049 -- attribute is never a remote type.
2054 then
2055 declare
2063 begin
2064 -- Check that Typ is a remote access-to-subprogram type
2068 -- Prefix (N) must statically denote a remote subprogram
2069 -- declared in a package specification.
2073 Attr = Attribute_Unrestricted_Access
2074 then
2089 or else
2091 then
2093 Error_Msg_N
2095 N);
2098 -- If we are generating code in distributed mode, perform
2099 -- semantic checks against corresponding remote entities.
2101 if Expander_Active
2103 then
2104 Check_Subtype_Conformant
2106 Old_Id => Designated_Type
2132 then
2137 -- Return if already analyzed
2144 -- Any case of Any_Type as the Etype value means that we had a
2145 -- previous error.
2154 -- The resolution of an Expression_With_Actions is determined by
2155 -- its Expression.
2163 -- If not overloaded, then we know the type, and all that needs doing
2164 -- is to check that this type is compatible with the context.
2170 -- In the overloaded case, we must select the interpretation that
2171 -- is compatible with the context (i.e. the type passed to Resolve)
2173 else
2174 -- Loop through possible interpretations
2183 -- We are only interested in interpretations that are compatible
2184 -- with the expected type, any other interpretations are ignored.
2189 Write_Eol;
2192 else
2193 -- Skip the current interpretation if it is disabled by an
2194 -- abstract operator. This action is performed only when the
2195 -- type against which we are resolving is the same as the
2196 -- type of the interpretation.
2203 then
2211 -- First matching interpretation
2219 -- Matching interpretation that is not the first, maybe an
2220 -- error, but there are some cases where preference rules are
2221 -- used to choose between the two possibilities. These and
2222 -- some more obscure cases are handled in Disambiguate.
2224 else
2225 -- If the current statement is part of a predefined library
2226 -- unit, then all interpretations which come from user level
2227 -- packages should not be considered. Check previous and
2228 -- current one.
2236 -- Previous interpretation must be discarded
2246 -- Otherwise apply further disambiguation steps
2251 -- Disambiguation has succeeded. Skip the remaining
2252 -- interpretations.
2262 else
2263 -- Before we issue an ambiguity complaint, check for the
2264 -- case of a subprogram call where at least one of the
2265 -- arguments is Any_Type, and if so suppress the message,
2266 -- since it is a cascaded error. This can also happen for
2267 -- a generalized indexing operation.
2272 then
2273 declare
2277 begin
2293 Write_Eol;
2306 then
2311 then
2315 -- Not that special case, so issue message using the flag
2316 -- Ambiguous to control printing of the header message
2317 -- only at the start of an ambiguous set.
2322 then
2323 Error_Msg_N
2326 else
2327 Error_Msg_NE -- CODEFIX
2335 Error_Msg_N
2337 else
2338 Error_Msg_N -- CODEFIX
2344 then
2345 Report_Ambiguous_Argument;
2351 -- By default, the error message refers to the candidate
2352 -- interpretation. But if it is a predefined operator, it
2353 -- is implicitly declared at the declaration of the type
2354 -- of the operand. Recover the sloc of that declaration
2355 -- for the error message.
2361 Standard_Standard
2362 then
2367 then
2375 Standard_Standard
2376 then
2381 then
2385 -- If this is an indirect call, use the subprogram_type
2386 -- in the message, to have a meaningful location. Also
2387 -- indicate if this is an inherited operation, created
2388 -- by a type declaration.
2393 then
2395 Error_Msg_Sloc :=
2397 else
2404 then
2405 -- Special-case the message for universal_fixed
2406 -- operators, which are not declared with the type
2407 -- of the operand, but appear forever in Standard.
2411 then
2412 Error_Msg_N
2415 else
2416 Error_Msg_N
2420 elsif
2422 then
2423 Error_Msg_N
2425 else
2426 Error_Msg_N -- CODEFIX
2433 -- We have a matching interpretation, Expr_Type is the type
2434 -- from this interpretation, and Seen is the entity.
2436 -- For an operator, just set the entity name. The type will be
2437 -- set by the specific operator resolution routine.
2444 N_Character_Literal,
2445 N_Delta_Aggregate,
2446 N_If_Expression)
2447 then
2450 -- AI05-0139-2: Expression is overloaded because type has
2451 -- implicit dereference. If type matches context, no implicit
2452 -- dereference is involved. If the expression is an entity,
2453 -- generate a reference to it, as this is not done for an
2454 -- overloaded construct during analysis.
2470 then
2471 -- If the node is a general indexing, the dereference is
2472 -- is inserted when resolving the rewritten form, else
2473 -- insert it now.
2477 then
2481 -- For an explicit dereference, attribute reference, range,
2482 -- short-circuit form (which is not an operator node), or call
2483 -- with a name that is an explicit dereference, there is
2484 -- nothing to be done at this point.
2487 N_And_Then,
2488 N_Explicit_Dereference,
2489 N_Identifier,
2490 N_Indexed_Component,
2491 N_Or_Else,
2492 N_Range,
2493 N_Selected_Component,
2494 N_Slice)
2496 then
2499 -- For procedure or function calls, set the type of the name,
2500 -- and also the entity pointer for the prefix.
2504 then
2511 then
2516 -- For all other cases, just set the type of the Name
2518 else
2526 -- Move to next interpretation
2534 -- At this stage Found indicates whether or not an acceptable
2535 -- interpretation exists. If not, then we have an error, except that if
2536 -- the context is Any_Type as a result of some other error, then we
2537 -- suppress the error report.
2542 -- If type we are looking for is Void, then this is the procedure
2543 -- call case, and the error is simply that what we gave is not a
2544 -- procedure name (we think of procedure calls as expressions with
2545 -- types internally, but the user doesn't think of them this way).
2549 -- Special case message if function used as a procedure
2554 then
2555 Error_Msg_NE
2558 Error_Msg_N
2562 -- Otherwise give general message (not clear what cases this
2563 -- covers, but no harm in providing for them).
2565 else
2571 -- Otherwise we do have a subexpression with the wrong type
2573 -- Check for the case of an allocator which uses an access type
2574 -- instead of the designated type. This is a common error and we
2575 -- specialize the message, posting an error on the operand of the
2576 -- allocator, complaining that we expected the designated type of
2577 -- the allocator.
2583 then
2587 -- Check for view mismatch on Null in instances, for which the
2588 -- view-swapping mechanism has no identifier.
2594 then
2599 -- Check for an aggregate. Sometimes we can get bogus aggregates
2600 -- from misuse of parentheses, and we are about to complain about
2601 -- the aggregate without even looking inside it.
2603 -- Instead, if we have an aggregate of type Any_Composite, then
2604 -- analyze and resolve the component fields, and then only issue
2605 -- another message if we get no errors doing this (otherwise
2606 -- assume that the errors in the aggregate caused the problem).
2610 then
2611 -- Disable expansion in any case. If there is a type mismatch
2612 -- it may be fatal to try to expand the aggregate. The flag
2613 -- would otherwise be set to false when the error is posted.
2617 declare
2619 -- Check one aggregate, and set Found to True if we have a
2620 -- definite error in any of its elements
2623 -- Check one element of aggregate and set Found to True if
2624 -- we definitely have an error in the element.
2626 ----------------
2627 -- Check_Aggr --
2628 ----------------
2633 begin
2646 -- If this is a default-initialized component, then
2647 -- there is nothing to check. The box will be
2648 -- replaced by the appropriate call during late
2649 -- expansion.
2653 then
2662 ----------------
2663 -- Check_Elmt --
2664 ----------------
2667 begin
2668 -- If we have a nested aggregate, go inside it (to
2669 -- attempt a naked analyze-resolve of the aggregate can
2670 -- cause undesirable cascaded errors). Do not resolve
2671 -- expression if it needs a type from context, as for
2672 -- integer * fixed expression.
2677 else
2682 then
2692 begin
2697 -- Looks like we have a type error, but check for special case
2698 -- of Address wanted, integer found, with the configuration pragma
2699 -- Allow_Integer_Address active. If we have this case, introduce
2700 -- an unchecked conversion to allow the integer expression to be
2701 -- treated as an Address. The reverse case of integer wanted,
2702 -- Address found, is treated in an analogous manner.
2709 -- Under relaxed RM semantics silently replace occurrences of null
2710 -- by System.Address_Null.
2718 -- That special Allow_Integer_Address check did not apply, so we
2719 -- have a real type error. If an error message was issued already,
2720 -- Found got reset to True, so if it's still False, issue standard
2721 -- Wrong_Type message.
2725 declare
2728 begin
2734 -- Protected operation: retrieve operation name
2738 else
2743 Error_Msg_NE
2749 declare
2753 begin
2760 Error_Msg_NE
2766 else
2770 else
2776 Resolution_Failed;
2779 -- Test if we have more than one interpretation for the context
2782 Resolution_Failed;
2785 -- Only one intepretation
2787 else
2788 -- In Ada 2005, if we have something like "X : T := 2 + 2;", where
2789 -- the "+" on T is abstract, and the operands are of universal type,
2790 -- the above code will have (incorrectly) resolved the "+" to the
2791 -- universal one in Standard. Therefore check for this case and give
2792 -- an error. We can't do this earlier, because it would cause legal
2793 -- cases to get errors (when some other type has an abstract "+").
2799 then
2804 then
2805 Error_Msg_NE
2814 -- Here we have an acceptable interpretation for the context
2816 -- Propagate type information and normalize tree for various
2817 -- predefined operations. If the context only imposes a class of
2818 -- types, rather than a specific type, propagate the actual type
2819 -- downward.
2825 Typ = Any_Discrete
2826 then
2829 -- Any_Fixed is legal in a real context only if a specific fixed-
2830 -- point type is imposed. If Norman Cohen can be confused by this,
2831 -- it deserves a separate message.
2835 then
2842 -- A user-defined operator is transformed into a function call at
2843 -- this point, so that further processing knows that operators are
2844 -- really operators (i.e. are predefined operators). User-defined
2845 -- operators that are intrinsic are just renamings of the predefined
2846 -- ones, and need not be turned into calls either, but if they rename
2847 -- a different operator, we must transform the node accordingly.
2848 -- Instantiations of Unchecked_Conversion are intrinsic but are
2849 -- treated as functions, even if given an operator designator.
2854 then
2859 and then
2861 N_Subprogram_Renaming_Declaration
2862 then
2865 -- If the node is rewritten, it will be fully resolved in
2866 -- Rewrite_Renamed_Operator.
2875 when N_Aggregate =>
2876 Resolve_Aggregate (N, Ctx_Type);
2878 when N_Allocator =>
2879 Resolve_Allocator (N, Ctx_Type);
2881 when N_Short_Circuit =>
2882 Resolve_Short_Circuit (N, Ctx_Type);
2884 when N_Attribute_Reference =>
2885 Resolve_Attribute (N, Ctx_Type);
2887 when N_Case_Expression =>
2888 Resolve_Case_Expression (N, Ctx_Type);
2890 when N_Character_Literal =>
2891 Resolve_Character_Literal (N, Ctx_Type);
2893 when N_Delta_Aggregate =>
2894 Resolve_Delta_Aggregate (N, Ctx_Type);
2896 when N_Expanded_Name =>
2897 Resolve_Entity_Name (N, Ctx_Type);
2899 when N_Explicit_Dereference =>
2900 Resolve_Explicit_Dereference (N, Ctx_Type);
2902 when N_Expression_With_Actions =>
2903 Resolve_Expression_With_Actions (N, Ctx_Type);
2905 when N_Extension_Aggregate =>
2906 Resolve_Extension_Aggregate (N, Ctx_Type);
2908 when N_Function_Call =>
2909 Resolve_Call (N, Ctx_Type);
2911 when N_Identifier =>
2912 Resolve_Entity_Name (N, Ctx_Type);
2914 when N_If_Expression =>
2915 Resolve_If_Expression (N, Ctx_Type);
2917 when N_Indexed_Component =>
2918 Resolve_Indexed_Component (N, Ctx_Type);
2920 when N_Integer_Literal =>
2921 Resolve_Integer_Literal (N, Ctx_Type);
2923 when N_Membership_Test =>
2924 Resolve_Membership_Op (N, Ctx_Type);
2926 when N_Null =>
2927 Resolve_Null (N, Ctx_Type);
2929 when N_Op_And
2930 | N_Op_Or
2931 | N_Op_Xor
2932 =>
2933 Resolve_Logical_Op (N, Ctx_Type);
2935 when N_Op_Eq
2936 | N_Op_Ne
2937 =>
2938 Resolve_Equality_Op (N, Ctx_Type);
2940 when N_Op_Ge
2941 | N_Op_Gt
2942 | N_Op_Le
2943 | N_Op_Lt
2944 =>
2945 Resolve_Comparison_Op (N, Ctx_Type);
2947 when N_Op_Not =>
2948 Resolve_Op_Not (N, Ctx_Type);
2950 when N_Op_Add
2951 | N_Op_Divide
2952 | N_Op_Mod
2953 | N_Op_Multiply
2954 | N_Op_Rem
2955 | N_Op_Subtract
2956 =>
2957 Resolve_Arithmetic_Op (N, Ctx_Type);
2959 when N_Op_Concat =>
2960 Resolve_Op_Concat (N, Ctx_Type);
2962 when N_Op_Expon =>
2963 Resolve_Op_Expon (N, Ctx_Type);
2965 when N_Op_Abs
2966 | N_Op_Minus
2967 | N_Op_Plus
2968 =>
2969 Resolve_Unary_Op (N, Ctx_Type);
2971 when N_Op_Shift =>
2972 Resolve_Shift (N, Ctx_Type);
2974 when N_Procedure_Call_Statement =>
2975 Resolve_Call (N, Ctx_Type);
2977 when N_Operator_Symbol =>
2978 Resolve_Operator_Symbol (N, Ctx_Type);
2980 when N_Qualified_Expression =>
2981 Resolve_Qualified_Expression (N, Ctx_Type);
2983 -- Why is the following null, needs a comment ???
2985 when N_Quantified_Expression =>
2986 null;
2988 when N_Raise_Expression =>
2989 Resolve_Raise_Expression (N, Ctx_Type);
2991 when N_Raise_xxx_Error =>
2992 Set_Etype (N, Ctx_Type);
2994 when N_Range =>
2995 Resolve_Range (N, Ctx_Type);
2997 when N_Real_Literal =>
2998 Resolve_Real_Literal (N, Ctx_Type);
3000 when N_Reference =>
3001 Resolve_Reference (N, Ctx_Type);
3003 when N_Selected_Component =>
3004 Resolve_Selected_Component (N, Ctx_Type);
3006 when N_Slice =>
3007 Resolve_Slice (N, Ctx_Type);
3009 when N_String_Literal =>
3010 Resolve_String_Literal (N, Ctx_Type);
3012 when N_Target_Name =>
3013 Resolve_Target_Name (N, Ctx_Type);
3015 when N_Type_Conversion =>
3016 Resolve_Type_Conversion (N, Ctx_Type);
3018 when N_Unchecked_Expression =>
3019 Resolve_Unchecked_Expression (N, Ctx_Type);
3021 when N_Unchecked_Type_Conversion =>
3022 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
3023 end case;
3025 -- Mark relevant use-type and use-package clauses as effective using
3026 -- the original node because constant folding may have occured and
3027 -- removed references that need to be examined.
3029 if Nkind (Original_Node (N)) in N_Op then
3030 Mark_Use_Clauses (Original_Node (N));
3031 end if;
3033 -- Ada 2012 (AI05-0149): Apply an (implicit) conversion to an
3034 -- expression of an anonymous access type that occurs in the context
3035 -- of a named general access type, except when the expression is that
3036 -- of a membership test. This ensures proper legality checking in
3037 -- terms of allowed conversions (expressions that would be illegal to
3038 -- convert implicitly are allowed in membership tests).
3040 if Ada_Version >= Ada_2012
3041 and then Ekind (Ctx_Type) = E_General_Access_Type
3042 and then Ekind (Etype (N)) = E_Anonymous_Access_Type
3043 and then Nkind (Parent (N)) not in N_Membership_Test
3044 then
3045 Rewrite (N, Convert_To (Ctx_Type, Relocate_Node (N)));
3046 Analyze_And_Resolve (N, Ctx_Type);
3047 end if;
3049 -- If the subexpression was replaced by a non-subexpression, then
3050 -- all we do is to expand it. The only legitimate case we know of
3051 -- is converting procedure call statement to entry call statements,
3052 -- but there may be others, so we are making this test general.
3054 if Nkind (N) not in N_Subexpr then
3055 Debug_A_Exit ("resolving ", N, " (done)");
3056 Expand (N);
3057 return;
3058 end if;
3060 -- The expression is definitely NOT overloaded at this point, so
3061 -- we reset the Is_Overloaded flag to avoid any confusion when
3062 -- reanalyzing the node.
3064 Set_Is_Overloaded (N, False);
3066 -- Freeze expression type, entity if it is a name, and designated
3067 -- type if it is an allocator (RM 13.14(10,11,13)).
3069 -- Now that the resolution of the type of the node is complete, and
3070 -- we did not detect an error, we can expand this node. We skip the
3071 -- expand call if we are in a default expression, see section
3072 -- "Handling of Default Expressions" in Sem spec.
3074 Debug_A_Exit ("resolving ", N, " (done)");
3076 -- We unconditionally freeze the expression, even if we are in
3077 -- default expression mode (the Freeze_Expression routine tests this
3078 -- flag and only freezes static types if it is set).
3080 -- Ada 2012 (AI05-177): The declaration of an expression function
3081 -- does not cause freezing, but we never reach here in that case.
3082 -- Here we are resolving the corresponding expanded body, so we do
3083 -- need to perform normal freezing.
3085 -- As elsewhere we do not emit freeze node within a generic. We make
3086 -- an exception for entities that are expressions, only to detect
3087 -- misuses of deferred constants and preserve the output of various
3088 -- tests.
3090 if not Inside_A_Generic or else Is_Entity_Name (N) then
3091 Freeze_Expression (N);
3092 end if;
3094 -- Now we can do the expansion
3096 Expand (N);
3097 end if;
3098 end Resolve;
3100 -------------
3101 -- Resolve --
3102 -------------
3104 -- Version with check(s) suppressed
3106 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
3107 begin
3108 if Suppress = All_Checks then
3109 declare
3110 Sva : constant Suppress_Array := Scope_Suppress.Suppress;
3111 begin
3112 Scope_Suppress.Suppress := (others => True);
3113 Resolve (N, Typ);
3114 Scope_Suppress.Suppress := Sva;
3115 end;
3117 else
3118 declare
3119 Svg : constant Boolean := Scope_Suppress.Suppress (Suppress);
3120 begin
3121 Scope_Suppress.Suppress (Suppress) := True;
3122 Resolve (N, Typ);
3123 Scope_Suppress.Suppress (Suppress) := Svg;
3124 end;
3125 end if;
3126 end Resolve;
3128 -------------
3129 -- Resolve --
3130 -------------
3132 -- Version with implicit type
3134 procedure Resolve (N : Node_Id) is
3135 begin
3136 Resolve (N, Etype (N));
3137 end Resolve;
3139 ---------------------
3140 -- Resolve_Actuals --
3141 ---------------------
3143 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
3144 Loc : constant Source_Ptr := Sloc (N);
3145 A : Node_Id;
3146 A_Id : Entity_Id;
3147 A_Typ : Entity_Id := Empty; -- init to avoid warning
3148 F : Entity_Id;
3149 F_Typ : Entity_Id;
3150 Prev : Node_Id := Empty;
3151 Orig_A : Node_Id;
3152 Real_F : Entity_Id := Empty; -- init to avoid warning
3154 Real_Subp : Entity_Id;
3155 -- If the subprogram being called is an inherited operation for
3156 -- a formal derived type in an instance, Real_Subp is the subprogram
3157 -- that will be called. It may have different formal names than the
3158 -- operation of the formal in the generic, so after actual is resolved
3159 -- the name of the actual in a named association must carry the name
3160 -- of the actual of the subprogram being called.
3162 procedure Check_Aliased_Parameter;
3163 -- Check rules on aliased parameters and related accessibility rules
3164 -- in (RM 3.10.2 (10.2-10.4)).
3166 procedure Check_Argument_Order;
3167 -- Performs a check for the case where the actuals are all simple
3168 -- identifiers that correspond to the formal names, but in the wrong
3169 -- order, which is considered suspicious and cause for a warning.
3171 procedure Check_Prefixed_Call;
3172 -- If the original node is an overloaded call in prefix notation,
3174 -- Try_Object_Operation has already verified that there is a valid
3175 -- interpretation, but the form of the actual can only be determined
3176 -- once the primitive operation is identified.
3179 -- Emit an error concerning the illegal usage of an effectively volatile
3180 -- object in interfering context (SPARK RM 7.13(12)).
3183 -- If the actual is missing in a call, insert in the actuals list
3184 -- an instance of the default expression. The insertion is always
3185 -- a named association.
3188 -- Check whether T1 and T2, or their full views, are derived from a
3189 -- common type. Used to enforce the restrictions on array conversions
3190 -- of AI95-00246.
3193 -- Predicate to determine whether an actual that is a concatenation
3194 -- will be evaluated statically and does not need a transient scope.
3195 -- This must be determined before the actual is resolved and expanded
3196 -- because if needed the transient scope must be introduced earlier.
3198 -----------------------------
3199 -- Check_Aliased_Parameter --
3200 -----------------------------
3205 begin
3213 else
3220 -- In a generic body assume the worst for generic formals:
3221 -- they can have a constrained partial view (AI05-041).
3227 then
3230 else
3235 else
3247 then
3255 then
3256 Error_Msg_N
3262 --------------------------
3263 -- Check_Argument_Order --
3264 --------------------------
3267 begin
3268 -- Nothing to do if no parameters, or original node is neither a
3269 -- function call nor a procedure call statement (happens in the
3270 -- operator-transformed-to-function call case), or the call does
3271 -- not come from source, or this warning is off.
3273 if not Warn_On_Parameter_Order
3277 then
3281 declare
3284 begin
3285 -- Nothing to do if only one parameter
3291 -- Here if at least two arguments
3293 declare
3299 -- Set True if an out of order case is found
3301 begin
3302 -- Collect identifier names of actuals, fail if any actual is
3303 -- not a simple identifier, and record max length of name.
3309 else
3315 -- If we got this far, all actuals are identifiers and the list
3316 -- of their names is stored in the Actuals array.
3321 -- If we ran out of formals, that's odd, probably an error
3322 -- which will be detected elsewhere, but abandon the search.
3328 -- If name matches and is in order OK
3333 else
3334 -- If no match, see if it is elsewhere in list and if so
3335 -- flag potential wrong order if type is compatible.
3339 and then
3341 then
3347 -- No match
3355 -- If Formals left over, also probably an error, skip warning
3361 -- Here we give the warning if something was out of order
3364 Error_Msg_N
3371 -------------------------
3372 -- Check_Prefixed_Call --
3373 -------------------------
3382 begin
3383 -- Check whether the call is a prefixed call, with or without
3384 -- additional actuals.
3387 or else
3393 then
3396 then
3397 -- Introduce dereference on object in prefix
3399 New_A :=
3407 then
3408 -- Introduce an implicit 'Access in prefix
3411 Error_Msg_NE
3427 ---------------------------------------
3428 -- Flag_Effectively_Volatile_Objects --
3429 ---------------------------------------
3433 -- Determine whether arbitrary node N denotes an effectively volatile
3434 -- object and if it does, emit an error.
3436 -----------------
3437 -- Flag_Object --
3438 -----------------
3443 begin
3444 -- Do not consider nested function calls because they have already
3445 -- been processed during their own resolution.
3457 then
3458 Error_Msg_N
3470 -- Start of processing for Flag_Effectively_Volatile_Objects
3472 begin
3476 --------------------
3477 -- Insert_Default --
3478 --------------------
3484 begin
3485 -- Missing argument in call, nothing to insert
3490 else
3491 -- Note that we do a full New_Copy_Tree, so that any associated
3492 -- Itypes are properly copied. This may not be needed any more,
3493 -- but it does no harm as a safety measure. Defaults of a generic
3494 -- formal may be out of bounds of the corresponding actual (see
3495 -- cc1311b) and an additional check may be required.
3497 Actval :=
3498 New_Copy_Tree
3503 -- Propagate dimension information, if any.
3509 then
3515 then
3518 then
3519 -- If default is a real literal, do not introduce a
3520 -- conversion whose effect may depend on the run-time
3521 -- size of universal real.
3525 else
3536 -- Resolve aggregates with their base type, to avoid scope
3537 -- anomalies: the subtype was first built in the subprogram
3538 -- declaration, and the current call may be nested.
3542 else
3546 else
3549 -- See note above concerning aggregates
3553 then
3556 -- Resolve entities with their own type, which may differ from
3557 -- the type of a reference in a generic context (the view
3558 -- swapping mechanism did not anticipate the re-analysis of
3559 -- default values in calls).
3564 else
3569 -- If default is a tag indeterminate function call, propagate tag
3570 -- to obtain proper dispatching.
3574 then
3579 -- If the default expression raises constraint error, then just
3580 -- silently replace it with an N_Raise_Constraint_Error node, since
3581 -- we already gave the warning on the subprogram spec. If node is
3582 -- already a Raise_Constraint_Error leave as is, to prevent loops in
3583 -- the warnings removal machinery.
3587 then
3596 Assoc :=
3601 -- Case of insertion is first named actual
3605 then
3612 else
3616 else
3620 -- Case of insertion is not first named actual
3622 else
3623 Set_Next_Named_Actual
3635 -------------------
3636 -- Same_Ancestor --
3637 -------------------
3643 begin
3646 then
3652 then
3659 --------------------------
3660 -- Static_Concatenation --
3661 --------------------------
3664 begin
3671 -- Concatenation is static when both operands are static and
3672 -- the concatenation operator is a predefined one.
3675 and then
3677 and then
3682 declare
3684 begin
3687 and then
3691 else
3697 -- Start of processing for Resolve_Actuals
3699 begin
3700 Check_Argument_Order;
3704 and then In_Instance
3707 then
3709 else
3714 Check_Prefixed_Call;
3728 -- If we have an error in any actual or formal, indicated by a type
3729 -- of Any_Type, then abandon resolution attempt, and set result type
3730 -- to Any_Type. Skip this if the actual is a Raise_Expression, whose
3731 -- type is imposed from context.
3735 then
3742 -- Case where actual is present
3744 -- If the actual is an entity, generate a reference to it now. We
3745 -- do this before the actual is resolved, because a formal of some
3746 -- protected subprogram, or a task discriminant, will be rewritten
3747 -- during expansion, and the source entity reference may be lost.
3752 then
3753 -- Annotate the tree by creating a variable reference marker when
3754 -- the actual denotes a variable reference, in case the reference
3755 -- is folded or optimized away. The variable reference marker is
3756 -- automatically saved for later examination by the ABE Processing
3757 -- phase. The status of the reference is set as follows:
3759 -- status mode
3760 -- read IN, IN OUT
3761 -- write IN OUT, OUT
3763 Build_Variable_Reference_Marker
3773 then
3780 -- RM 6.4.1(12): For an out parameter that is passed by
3781 -- copy, the formal parameter object is created, and:
3783 -- * For an access type, the formal parameter is initialized
3784 -- from the value of the actual, without checking that the
3785 -- value satisfies any constraint, any predicate, or any
3786 -- exclusion of the null value.
3788 -- * For a scalar type that has the Default_Value aspect
3789 -- specified, the formal parameter is initialized from the
3790 -- value of the actual, without checking that the value
3791 -- satisfies any constraint or any predicate.
3792 -- I do not understand why this case is included??? this is
3793 -- not a case where an OUT parameter is treated as IN OUT.
3795 -- * For a composite type with discriminants or that has
3796 -- implicit initial values for any subcomponents, the
3797 -- behavior is as for an in out parameter passed by copy.
3799 -- Hence for these cases we generate the read reference now
3800 -- (the write reference will be generated later by
3801 -- Note_Possible_Modification).
3804 and then
3806 or else
3808 and then
3810 or else
3813 or else Is_Partially_Initialized_Type
3815 then
3825 then
3826 -- If style checking mode on, check match of formal name
3834 -- If the formal is Out or In_Out, do not resolve and expand the
3835 -- conversion, because it is subsequently expanded into explicit
3836 -- temporaries and assignments. However, the object of the
3837 -- conversion can be resolved. An exception is the case of tagged
3838 -- type conversion with a class-wide actual. In that case we want
3839 -- the tag check to occur and no temporary will be needed (no
3840 -- representation change can occur) and the parameter is passed by
3841 -- reference, so we go ahead and resolve the type conversion.
3842 -- Another exception is the case of reference to component or
3843 -- subcomponent of a bit-packed array, in which case we want to
3844 -- defer expansion to the point the in and out assignments are
3845 -- performed.
3850 then
3853 then
3854 -- In a view conversion, the conversion must be legal in
3855 -- both directions, and thus both component types must be
3856 -- aliased, or neither (4.6 (8)).
3858 -- The extra rule in 4.6 (24.9.2) seems unduly restrictive:
3859 -- the privacy requirement should not apply to generic
3860 -- types, and should be checked in an instance. ARG query
3861 -- is in order ???
3865 then
3866 Error_Msg_N
3870 -- Comment here??? what set of cases???
3872 elsif
3874 then
3875 -- Check view conv between unrelated by ref array types
3879 then
3880 Error_Msg_N
3884 -- In Ada 2005 mode, check view conversion component
3885 -- type cannot be private, tagged, or volatile. Note
3886 -- that we only apply this to source conversions. The
3887 -- generated code can contain conversions which are
3888 -- not subject to this test, and we cannot extract the
3889 -- component type in such cases since it is not present.
3893 then
3894 declare
3896 Component_Type
3898 begin
3903 then
3904 Error_Msg_N
3915 -- Resolve expression if conversion is all OK
3920 then
3924 -- If the actual is a function call that returns a limited
3925 -- unconstrained object that needs finalization, create a
3926 -- transient scope for it, so that it can receive the proper
3927 -- finalization list.
3932 and then Expander_Active
3934 then
3938 -- A small optimization: if one of the actuals is a concatenation
3939 -- create a block around a procedure call to recover stack space.
3940 -- This alleviates stack usage when several procedure calls in
3941 -- the same statement list use concatenation. We do not perform
3942 -- this wrapping for code statements, where the argument is a
3943 -- static string, and we want to preserve warnings involving
3944 -- sequences of such statements.
3948 and then Expander_Active
3949 and then
3953 then
3957 else
3961 and then
3964 then
3965 Error_Msg_N
3978 -- (Ada 2005: AI-251): If the actual is an allocator whose
3979 -- directly designated type is a class-wide interface, we build
3980 -- an anonymous access type to use it as the type of the
3981 -- allocator. Later, when the subprogram call is expanded, if
3982 -- the interface has a secondary dispatch table the expander
3983 -- will add a type conversion to force the correct displacement
3984 -- of the pointer.
3987 declare
3993 begin
3996 then
3999 Set_Directly_Designated_Type
4004 -- Ada 2005, AI-162:If the actual is an allocator, the
4005 -- innermost enclosing statement is the master of the
4006 -- created object. This needs to be done with expansion
4007 -- enabled only, otherwise the transient scope will not
4008 -- be removed in the expansion of the wrapped construct.
4011 and then Expander_Active
4012 then
4022 -- (Ada 2005): The call may be to a primitive operation of a
4023 -- tagged synchronized type, declared outside of the type. In
4024 -- this case the controlling actual must be converted to its
4025 -- corresponding record type, which is the formal type. The
4026 -- actual may be a subtype, either because of a constraint or
4027 -- because it is a generic actual, so use base type to locate
4028 -- concurrent type.
4035 then
4036 -- If the actual is overloaded, look for an interpretation
4037 -- that has a synchronized type.
4042 else
4043 declare
4047 begin
4052 then
4062 declare
4065 begin
4068 else
4072 -- Tagged synchronized type (case 1): the actual is a
4073 -- concurrent type.
4077 then
4079 Unchecked_Convert_To
4083 -- Tagged synchronized type (case 2): the formal is a
4084 -- concurrent type.
4087 and then Present
4092 then
4095 -- Common case
4097 else
4102 -- Not a synchronized operation
4104 else
4112 -- An actual cannot be an untagged formal incomplete type
4117 then
4118 Error_Msg_N
4124 N_Procedure_Call_Statement)
4125 then
4126 -- In formal mode, check that actual parameters matching
4127 -- formals of tagged types are objects (or ancestor type
4128 -- conversions of objects), not general expressions.
4135 declare
4140 begin
4142 Check_SPARK_05_Restriction
4145 -- In formal mode, the only view conversions are those
4146 -- involving ancestor conversion of an extended type.
4148 elsif not
4154 then
4155 if Ekind_In
4157 then
4158 Check_SPARK_05_Restriction
4161 else
4162 Check_SPARK_05_Restriction
4166 else
4171 else
4175 -- In formal mode, the only view conversions are those
4176 -- involving ancestor conversion of an extended type.
4180 then
4181 Check_SPARK_05_Restriction
4187 -- has warnings suppressed, then we reset Never_Set_In_Source for
4188 -- the calling entity. The reason for this is to catch cases like
4189 -- GNAT.Spitbol.Patterns.Vstring_Var where the called subprogram
4190 -- uses trickery to modify an IN parameter.
4197 then
4201 -- Perform error checks for IN and IN OUT parameters
4205 -- Check unset reference. For scalar parameters, it is clearly
4206 -- wrong to pass an uninitialized value as either an IN or
4207 -- IN-OUT parameter. For composites, it is also clearly an
4208 -- error to pass a completely uninitialized value as an IN
4209 -- parameter, but the case of IN OUT is trickier. We prefer
4210 -- not to give a warning here. For example, suppose there is
4211 -- a routine that sets some component of a record to False.
4212 -- It is perfectly reasonable to make this IN-OUT and allow
4213 -- either initialized or uninitialized records to be passed
4214 -- in this case.
4216 -- For partially initialized composite values, we also avoid
4217 -- warnings, since it is quite likely that we are passing a
4218 -- partially initialized value and only the initialized fields
4219 -- will in fact be read in the subprogram.
4224 then
4228 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
4229 -- actual to a nested call, since this constitutes a reading of
4230 -- the parameter, which is not allowed.
4235 then
4240 -- In -gnatd.q mode, forget that a given array is constant when
4241 -- it is passed as an IN parameter to a foreign-convention
4242 -- subprogram. This is in case the subprogram evilly modifies the
4243 -- object. Of course, correct code would use IN OUT.
4245 if Debug_Flag_Dot_Q
4251 then
4255 -- Case of OUT or IN OUT parameter
4259 -- For an Out parameter, check for useless assignment. Note
4260 -- that we can't set Last_Assignment this early, because we may
4261 -- kill current values in Resolve_Call, and that call would
4262 -- clobber the Last_Assignment field.
4264 -- Note: call Warn_On_Useless_Assignment before doing the check
4265 -- below for Is_OK_Variable_For_Out_Formal so that the setting
4266 -- of Referenced_As_LHS/Referenced_As_Out_Formal properly
4267 -- reflects the last assignment, not this one.
4274 then
4279 -- Validate the form of the actual. Note that the call to
4280 -- Is_OK_Variable_For_Out_Formal generates the required
4281 -- reference in this case.
4283 -- A call to an initialization procedure for an aggregate
4284 -- component may initialize a nested component of a constant
4285 -- designated object. In this context the object is variable.
4289 then
4295 then
4296 Error_Msg_N
4301 Error_Msg_N
4308 -- What's the following about???
4312 else
4313 Kill_All_Checks;
4322 -- Apply appropriate constraint/predicate checks for IN [OUT] case
4326 -- Apply predicate tests except in certain special cases. Note
4327 -- that it might be more consistent to apply these only when
4328 -- expansion is active (in Exp_Ch6.Expand_Actuals), as we do
4329 -- for the outbound predicate tests ??? In any case indicate
4330 -- the function being called, for better warnings if the call
4331 -- leads to an infinite recursion.
4337 -- Apply required constraint checks
4339 -- Gigi looks at the check flag and uses the appropriate types.
4340 -- For now since one flag is used there is an optimization
4341 -- which might not be done in the IN OUT case since Gigi does
4342 -- not do any analysis. More thought required about this ???
4344 -- In fact is this comment obsolete??? doesn't the expander now
4345 -- generate all these tests anyway???
4358 then
4361 -- For view conversions of a discriminated object, apply
4362 -- check to object itself, the conversion alreay has the
4363 -- proper type.
4367 then
4374 then
4380 then
4383 else
4387 -- Ada 2005 (AI-231): Note that the controlling parameter case
4388 -- already existed in Ada 95, which is partially checked
4389 -- elsewhere (see Checks), and we don't want the warning
4390 -- message to differ.
4395 then
4397 Apply_Compile_Time_Constraint_Error
4403 Apply_Compile_Time_Constraint_Error
4412 -- Checks for OUT parameters and IN OUT parameters
4416 -- If there is a type conversion, make sure the return value
4417 -- meets the constraints of the variable before the conversion.
4421 Apply_Scalar_Range_Check
4424 -- In addition, the returned value of the parameter must
4425 -- satisfy the bounds of the object type (see comment
4426 -- below).
4430 else
4431 Apply_Range_Check
4435 -- If no conversion, apply scalar range checks and length check
4436 -- based on the subtype of the actual (NOT that of the formal).
4437 -- This indicates that the check takes place on return from the
4438 -- call. During expansion the required constraint checks are
4439 -- inserted. In GNATprove mode, in the absence of expansion,
4440 -- the flag indicates that the returned value is valid.
4442 else
4448 then
4450 else
4455 -- Note: we do not apply the predicate checks for the case of
4456 -- OUT and IN OUT parameters. They are instead applied in the
4457 -- Expand_Actuals routine in Exp_Ch6.
4460 -- An actual associated with an access parameter is implicitly
4461 -- converted to the anonymous access type of the formal and must
4462 -- satisfy the legality checks for access conversions.
4466 Error_Msg_N
4470 -- If the actual is an access selected component of a variable,
4471 -- the call may modify its designated object. It is reasonable
4472 -- to treat this as a potential modification of the enclosing
4473 -- record, to prevent spurious warnings that it should be
4474 -- declared as a constant, because intuitively programmers
4475 -- regard the designated subcomponent as part of the record.
4480 then
4485 -- Check bad case of atomic/volatile argument (RM C.6(12))
4489 then
4492 then
4493 Error_Msg_NE
4499 then
4500 Error_Msg_NE
4506 -- Check that subprograms don't have improper controlling
4507 -- arguments (RM 3.9.2 (9)).
4509 -- A primitive operation may have an access parameter of an
4510 -- incomplete tagged type, but a dispatching call is illegal
4511 -- if the type is still incomplete.
4517 declare
4519 begin
4523 then
4524 Error_Msg_NE
4535 -- Apply legality rule 3.9.2 (9/1)
4540 and then not In_Instance
4541 then
4546 Error_Msg_NE
4550 -- Apply the checks described in 3.10.2(27): if the context is a
4551 -- specific access-to-object, the actual cannot be class-wide.
4552 -- Use base type to exclude access_to_subprogram cases.
4559 and then
4564 -- Disable these checks for call to imported C++ subprograms
4566 and then not
4570 then
4571 Error_Msg_N
4576 Error_Msg_NE
4581 Check_Aliased_Parameter;
4585 -- If it is a named association, treat the selector_name as a
4586 -- proper identifier, and mark the corresponding entity.
4590 -- Ignore reference in SPARK mode, as it refers to an entity not
4591 -- in scope at the point of reference, so the reference should
4592 -- be ignored for computing effects of subprograms.
4594 and then not GNATprove_Mode
4595 then
4596 -- If subprogram is overridden, use name of formal that
4597 -- is being called.
4603 else
4617 -- The following checks are only relevant when SPARK_Mode is on as
4618 -- they are not standard Ada legality rule. Internally generated
4619 -- temporaries are ignored.
4623 -- An effectively volatile object may act as an actual when the
4624 -- corresponding formal is of a non-scalar effectively volatile
4625 -- type (SPARK RM 7.1.3(11)).
4629 then
4632 -- An effectively volatile object may act as an actual in a
4633 -- call to an instance of Unchecked_Conversion.
4634 -- (SPARK RM 7.1.3(11)).
4639 -- The actual denotes an object
4642 Error_Msg_N
4646 -- Otherwise the actual denotes an expression. Inspect the
4647 -- expression and flag each effectively volatile object with
4648 -- enabled property Async_Writers or Effective_Reads as illegal
4649 -- because it apprears within an interfering context. Note that
4650 -- this is usually done in Resolve_Entity_Name, but when the
4651 -- effectively volatile object appears as an actual in a call,
4652 -- the call must be resolved first.
4654 else
4658 -- An effectively volatile variable cannot act as an actual
4659 -- parameter in a procedure call when the variable has enabled
4660 -- property Effective_Reads and the corresponding formal is of
4661 -- mode IN (SPARK RM 7.1.3(10)).
4666 then
4672 then
4673 Error_Msg_NE
4684 -- A formal parameter of a specific tagged type whose related
4685 -- subprogram is subject to pragma Extensions_Visible with value
4686 -- "False" cannot act as an actual in a subprogram with value
4687 -- "True" (SPARK RM 6.1.7(3)).
4691 Extensions_Visible_True
4692 then
4693 Error_Msg_N
4696 Error_Msg_NE
4700 -- The actual parameter of a Ghost subprogram whose formal is of
4701 -- mode IN OUT or OUT must be a Ghost variable (SPARK RM 6.9(12)).
4709 then
4710 Error_Msg_NE
4716 else
4723 -- Case where actual is not present
4725 else
4726 Insert_Default;
4737 -----------------------
4738 -- Resolve_Allocator --
4739 -----------------------
4751 procedure Check_Allocator_Discrim_Accessibility
4754 -- Check that accessibility level associated with an access discriminant
4755 -- initialized in an allocator by the expression Disc_Exp is not deeper
4756 -- than the level of the allocator type Alloc_Typ. An error message is
4757 -- issued if this condition is violated. Specialized checks are done for
4758 -- the cases of a constraint expression which is an access attribute or
4759 -- an access discriminant.
4762 -- If the allocator is an actual in a call, it is allowed to be class-
4763 -- wide when the context is not because it is a controlling actual.
4765 -------------------------------------------
4766 -- Check_Allocator_Discrim_Accessibility --
4767 -------------------------------------------
4769 procedure Check_Allocator_Discrim_Accessibility
4772 is
4773 begin
4776 then
4777 Error_Msg_N
4780 -- When the expression is an Access attribute the level of the prefix
4781 -- object must not be deeper than that of the allocator's type.
4785 Attribute_Access
4788 then
4789 Error_Msg_N
4791 Disc_Exp);
4793 -- When the expression is an access discriminant the check is against
4794 -- the level of the prefix object.
4800 then
4801 Error_Msg_N
4803 Disc_Exp);
4805 -- All other cases are legal
4807 else
4812 ----------------------------
4813 -- In_Dispatching_Context --
4814 ----------------------------
4819 begin
4825 -- Start of processing for Resolve_Allocator
4827 begin
4828 -- Replace general access with specific type
4838 -- For qualified expression, resolve the expression using the given
4839 -- subtype (nothing to do for type mark, subtype indication)
4844 and then not In_Dispatching_Context
4845 then
4846 Error_Msg_N
4854 -- Allocators generated by the build-in-place expansion mechanism
4855 -- are explicitly marked as coming from source but do not need to be
4856 -- checked for limited initialization. To exclude this case, ensure
4857 -- that the parent of the allocator is a source node.
4858 -- The return statement constructed for an Expression_Function does
4859 -- not come from source but requires a limited check.
4863 and then
4865 or else
4869 and then not In_Instance_Body
4870 then
4873 Error_Msg_N
4876 else
4877 Error_Msg_N
4885 -- A qualified expression requires an exact match of the type. Class-
4886 -- wide matching is not allowed.
4891 then
4895 -- Calls to build-in-place functions are not currently supported in
4896 -- allocators for access types associated with a simple storage pool.
4897 -- Supporting such allocators may require passing additional implicit
4898 -- parameters to build-in-place functions (or a significant revision
4899 -- of the current b-i-p implementation to unify the handling for
4900 -- multiple kinds of storage pools). ???
4904 then
4905 declare
4908 begin
4910 and then
4911 Present (Get_Rep_Pragma
4913 then
4914 Error_Msg_N
4921 -- A special accessibility check is needed for allocators that
4922 -- constrain access discriminants. The level of the type of the
4923 -- expression used to constrain an access discriminant cannot be
4924 -- deeper than the type of the allocator (in contrast to access
4925 -- parameters, where the level of the actual can be arbitrary).
4927 -- We can't use Valid_Conversion to perform this check because in
4928 -- general the type of the allocator is unrelated to the type of
4929 -- the access discriminant.
4933 then
4940 then
4943 -- Get the first component expression of the aggregate
4953 else
4957 else
4976 else
4981 else
4990 -- For a subtype mark or subtype indication, freeze the subtype
4992 else
4996 Error_Msg_N
5000 -- A special accessibility check is needed for allocators that
5001 -- constrain access discriminants. The level of the type of the
5002 -- expression used to constrain an access discriminant cannot be
5003 -- deeper than the type of the allocator (in contrast to access
5004 -- parameters, where the level of the actual can be arbitrary).
5005 -- We can't use Valid_Conversion to perform this check because
5006 -- in general the type of the allocator is unrelated to the type
5007 -- of the access discriminant.
5012 then
5022 else
5036 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
5037 -- check that the level of the type of the created object is not deeper
5038 -- than the level of the allocator's access type, since extensions can
5039 -- now occur at deeper levels than their ancestor types. This is a
5040 -- static accessibility level check; a run-time check is also needed in
5041 -- the case of an initialized allocator with a class-wide argument (see
5042 -- Expand_Allocator_Expression).
5046 then
5047 declare
5050 begin
5055 else
5061 then
5064 Error_Msg_N
5073 -- Do not apply Ada 2005 accessibility checks on a class-wide
5074 -- allocator if the type given in the allocator is a formal
5075 -- type. A run-time check will be performed in the instance.
5085 -- Check for allocation from an empty storage pool
5090 -- If the context is an unchecked conversion, as may happen within an
5091 -- inlined subprogram, the allocator is being resolved with its own
5092 -- anonymous type. In that case, if the target type has a specific
5093 -- storage pool, it must be inherited explicitly by the allocator type.
5097 then
5098 Set_Associated_Storage_Pool
5106 -- Check that an allocator with task parts isn't for a nested access
5107 -- type when restriction No_Task_Hierarchy applies.
5111 then
5115 -- An illegal allocator may be rewritten as a raise Program_Error
5116 -- statement.
5120 -- Avoid coextension processing for an allocator that is the
5121 -- expansion of a build-in-place function call.
5125 N_Qualified_Expression
5127 N_Function_Call
5128 and then Is_Expanded_Build_In_Place_Call
5130 then
5133 else
5134 -- An anonymous access discriminant is the definition of a
5135 -- coextension.
5139 N_Discriminant_Specification
5140 then
5141 declare
5145 begin
5148 -- Ada 2012 AI05-0052: If the designated type of the
5149 -- allocator is limited, then the allocator shall not
5150 -- be used to define the value of an access discriminant
5151 -- unless the discriminated type is immutably limited.
5156 then
5157 Error_Msg_N
5160 N);
5164 -- Avoid marking an allocator as a dynamic coextension if it is
5165 -- within a static construct.
5170 -- Finalization and deallocation of coextensions utilizes an
5171 -- approximate implementation which does not directly adhere
5172 -- to the semantic rules. Warn on potential issues involving
5173 -- coextensions.
5176 Error_Msg_N
5179 else
5180 Error_Msg_N
5186 -- Cleanup for potential static coextensions
5188 else
5192 -- Anonymous access-to-controlled objects are not finalized on
5193 -- time because this involves run-time ownership and currently
5194 -- this property is not available. In rare cases the object may
5195 -- not be finalized at all. Warn on potential issues involving
5196 -- anonymous access-to-controlled objects.
5200 then
5201 Error_Msg_N
5211 -- Report a simple error: if the designated object is a local task,
5212 -- its body has not been seen yet, and its activation will fail an
5213 -- elaboration check.
5220 then
5226 -- Ada 2012 (AI05-0111-3): Detect an attempt to allocate a task or a
5227 -- type with a task component on a subpool. This action must raise
5228 -- Program_Error at runtime.
5234 then
5246 ---------------------------
5247 -- Resolve_Arithmetic_Op --
5248 ---------------------------
5250 -- Used for resolving all arithmetic operators except exponentiation
5261 -- We do the resolution using the base type, because intermediate values
5262 -- in expressions always are of the base type, not a subtype of it.
5265 -- Returns True if N is in a context that expects "any real type"
5268 -- Return True iff given type is Integer or universal real/integer
5271 -- Choose type of integer literal in fixed-point operation to conform
5272 -- to available fixed-point type. T is the type of the other operand,
5273 -- which is needed to determine the expected type of N.
5276 -- Set operand type to T if universal
5278 -------------------------------
5279 -- Expected_Type_Is_Any_Real --
5280 -------------------------------
5283 begin
5284 -- N is the expression after "delta" in a fixed_point_definition;
5285 -- see RM-3.5.9(6):
5288 N_Decimal_Fixed_Point_Definition,
5290 -- N is one of the bounds in a real_range_specification;
5291 -- see RM-3.5.7(5):
5293 N_Real_Range_Specification,
5295 -- N is the expression of a delta_constraint;
5296 -- see RM-J.3(3):
5298 N_Delta_Constraint);
5301 -----------------------------
5302 -- Is_Integer_Or_Universal --
5303 -----------------------------
5310 begin
5316 else
5322 then
5333 ----------------------------
5334 -- Set_Mixed_Mode_Operand --
5335 ----------------------------
5341 begin
5344 -- A universal integer literal is resolved as standard integer
5345 -- except in the case of a fixed-point result, where we leave it
5346 -- as universal (to be handled by Exp_Fixd later on)
5350 else
5358 then
5359 -- A universal real can appear in a fixed-type context. We resolve
5360 -- the literal with that context, even though this might raise an
5361 -- exception prematurely (the other operand may be zero).
5368 then
5369 -- Integer arg in mixed-mode operation. Resolve with universal
5370 -- type, in case preference rule must be applied.
5376 then
5377 -- Not a mixed-mode operation, resolve with context
5383 -- N may itself be a mixed-mode operation, so use context type
5390 then
5391 -- Must be (fixed * fixed) operation, operand must have one
5392 -- compatible interpretation.
5399 then
5400 -- C * F(X) in a fixed context, where C is a real literal or a
5401 -- fixed-point expression. F must have either a fixed type
5402 -- interpretation or an integer interpretation, but not both.
5409 else
5416 else
5424 -- Reanalyze the literal with the fixed type of the context. If
5425 -- context is Universal_Fixed, we are within a conversion, leave
5426 -- the literal as a universal real because there is no usable
5427 -- fixed type, and the target of the conversion plays no role in
5428 -- the resolution.
5430 declare
5434 begin
5437 else
5443 then
5445 else
5453 -- A universal real conditional expression can appear in a fixed-type
5454 -- context and must be resolved with that context to facilitate the
5455 -- code generation to the backend.
5460 then
5463 else
5468 ----------------------
5469 -- Set_Operand_Type --
5470 ----------------------
5473 begin
5476 then
5481 -- Start of processing for Resolve_Arithmetic_Op
5483 begin
5488 then
5492 -- Special-case for mixed-mode universal expressions or fixed point type
5493 -- operation: each argument is resolved separately. The same treatment
5494 -- is required if one of the operands of a fixed point operation is
5495 -- universal real, since in this case we don't do a conversion to a
5496 -- specific fixed-point type (instead the expander handles the case).
5498 -- Set the type of the node to its universal interpretation because
5499 -- legality checks on an exponentiation operand need the context.
5504 then
5515 or else
5518 then
5523 -- If context is a fixed type and one operand is integer, the other
5524 -- is resolved with the type of the context.
5529 then
5536 then
5540 -- If both operands are universal and the context is a floating
5541 -- point type, the operands are resolved to the type of the context.
5547 else
5552 -- Check the rule in RM05-4.5.5(19.1/2) disallowing universal_fixed
5553 -- multiplying operators from being used when the expected type is
5554 -- also universal_fixed. Note that B_Typ will be Universal_Fixed in
5555 -- some cases where the expected type is actually Any_Real;
5556 -- Expected_Type_Is_Any_Real takes care of that case.
5560 then
5564 N_Unchecked_Type_Conversion)
5565 then
5572 else
5575 and then not
5577 N_Unchecked_Type_Conversion)
5578 then
5579 Error_Msg_N
5584 -- The expected type is "any real type" in contexts like
5586 -- type T is delta <universal_fixed-expression> ...
5588 -- in which case we need to set the type to Universal_Real
5589 -- so that static expression evaluation will work properly.
5593 else
5603 then
5608 -- If no previous errors, this is only possible if one operand is
5609 -- overloaded and the context is universal. Resolve as such.
5614 else
5616 and then
5618 then
5622 -- If the context is Universal_Fixed and the operands are also
5623 -- universal fixed, this is an error, unless there is only one
5624 -- applicable fixed_point type (usually Duration).
5632 else
5637 else
5642 -- If one of the arguments was resolved to a non-universal type.
5643 -- label the result of the operation itself with the same type.
5644 -- Do the same for the universal argument, if any.
5656 -- In SPARK, a multiplication or division with operands of fixed point
5657 -- types must be qualified or explicitly converted to identify the
5658 -- result type.
5663 and then
5665 then
5666 Check_SPARK_05_Restriction
5670 -- Set overflow and division checking bit
5677 -- Give warning if explicit division by zero
5681 then
5687 or else
5690 then
5691 -- Specialize the warning message according to the operation.
5692 -- When SPARK_Mode is On, force a warning instead of an error
5693 -- in that case, as this likely corresponds to deactivated
5694 -- code. The following warnings are for the case
5699 -- For division, we have two cases, for float division
5700 -- of an unconstrained float type, on a machine where
5701 -- Machine_Overflows is false, we don't get an exception
5702 -- at run-time, but rather an infinity or Nan. The Nan
5703 -- case is pretty obscure, so just warn about infinities.
5707 and then not Machine_Overflows_On_Target
5708 then
5709 Error_Msg_N
5713 -- For all other cases, we get a Constraint_Error
5715 else
5716 Apply_Compile_Time_Constraint_Error
5723 Apply_Compile_Time_Constraint_Error
5729 Apply_Compile_Time_Constraint_Error
5734 -- Division by zero can only happen with division, rem,
5735 -- and mod operations.
5741 -- In GNATprove mode, we enable the division check so that
5742 -- GNATprove will issue a message if it cannot be proved.
5748 -- Otherwise just set the flag to check at run time
5750 else
5755 -- If Restriction No_Implicit_Conditionals is active, then it is
5756 -- violated if either operand can be negative for mod, or for rem
5757 -- if both operands can be negative.
5761 then
5762 declare
5769 -- Set if corresponding operand might be negative
5771 begin
5772 Determine_Range
5776 Determine_Range
5780 -- Check if we will be generating conditionals. There are two
5781 -- cases where that can happen, first for REM, the only case
5782 -- is largest negative integer mod -1, where the division can
5783 -- overflow, but we still have to give the right result. The
5784 -- front end generates a test for this annoying case. Here we
5785 -- just test if both operands can be negative (that's what the
5786 -- expander does, so we match its logic here).
5788 -- The second case is mod where either operand can be negative.
5789 -- In this case, the back end has to generate additional tests.
5792 or else
5794 then
5805 ------------------
5806 -- Resolve_Call --
5807 ------------------
5810 function Same_Or_Aliased_Subprograms
5813 -- Returns True if the subprogram entity S is the same as E or else
5814 -- S is an alias of E.
5816 ---------------------------------
5817 -- Same_Or_Aliased_Subprograms --
5818 ---------------------------------
5820 function Same_Or_Aliased_Subprograms
5823 is
5825 begin
5829 -- Local variables
5843 -- Start of processing for Resolve_Call
5845 begin
5846 -- Preserve relevant elaboration-related attributes of the context which
5847 -- are no longer available or very expensive to recompute once analysis,
5848 -- resolution, and expansion are over.
5850 Mark_Elaboration_Attributes
5856 -- The context imposes a unique interpretation with type Typ on a
5857 -- procedure or function call. Find the entity of the subprogram that
5858 -- yields the expected type, and propagate the corresponding formal
5859 -- constraints on the actuals. The caller has established that an
5860 -- interpretation exists, and emitted an error if not unique.
5862 -- First deal with the case of a call to an access-to-subprogram,
5863 -- dereference made explicit in Analyze_Call.
5869 else
5870 -- Find the interpretation whose type (a subprogram type) has a
5871 -- return type that is compatible with the context. Analysis of
5872 -- the node has established that one exists.
5891 -- If the prefix is not an entity, then resolve it
5897 -- For an indirect call, we always invalidate checks, since we do not
5898 -- know whether the subprogram is local or global. Yes we could do
5899 -- better here, e.g. by knowing that there are no local subprograms,
5900 -- but it does not seem worth the effort. Similarly, we kill all
5901 -- knowledge of current constant values.
5903 Kill_Current_Values;
5905 -- If this is a procedure call which is really an entry call, do
5906 -- the conversion of the procedure call to an entry call. Protected
5907 -- operations use the same circuitry because the name in the call
5908 -- can be an arbitrary expression with special resolution rules.
5913 then
5920 -- Annotate the tree by creating a call marker in case the original
5921 -- call is transformed by expansion. The call marker is automatically
5922 -- saved for later examination by the ABE Processing phase.
5926 -- Kill checks and constant values, as above for indirect case
5927 -- Who knows what happens when another task is activated?
5929 Kill_Current_Values;
5932 -- Normal subprogram call with name established in Resolve
5938 -- Otherwise we must have the case of an overloaded call
5940 else
5943 -- Initialize Nam to prevent warning (we know it will be assigned
5944 -- in the loop below, but the compiler does not know that).
5964 then
5965 -- The prefix is a parameterless function call that returns an access
5966 -- to subprogram. If parameters are present in the current call, add
5967 -- add an explicit dereference. We use the base type here because
5968 -- within an instance these may be subtypes.
5970 -- The dereference is added either in Analyze_Call or here. Should
5971 -- be consolidated ???
5980 -- Check that a call to Current_Task does not occur in an entry body
5983 declare
5986 begin
5988 loop
5991 -- Exclude calls that occur within the default of a formal
5992 -- parameter of the entry, since those are evaluated outside
5993 -- of the body.
6000 then
6003 Error_Msg_NE
6017 -- Check that a procedure call does not occur in the context of the
6018 -- entry call statement of a conditional or timed entry call. Note that
6019 -- the case of a call to a subprogram renaming of an entry will also be
6020 -- rejected. The test for N not being an N_Entry_Call_Statement is
6021 -- defensive, covering the possibility that the processing of entry
6022 -- calls might reach this point due to later modifications of the code
6023 -- above.
6028 then
6032 -- Ada 2005 (AI-345): If a procedure_call_statement is used
6033 -- for a procedure_or_entry_call, the procedure_name or
6034 -- procedure_prefix of the procedure_call_statement shall denote
6035 -- an entry renamed by a procedure, or (a view of) a primitive
6036 -- subprogram of a limited interface whose first parameter is
6037 -- a controlling parameter.
6042 then
6043 Error_Msg_N
6048 -- If the SPARK_05 restriction is active, we are not allowed
6049 -- to have a call to a subprogram before we see its completion.
6054 -- Don't flag strange internal calls
6059 -- Only flag calls in extended main source
6064 -- Exclude enumeration literals from this processing
6067 then
6068 Check_SPARK_05_Restriction
6072 -- Check that this is not a call to a protected procedure or entry from
6073 -- within a protected function.
6077 -- Freeze the subprogram name if not in a spec-expression. Note that
6078 -- we freeze procedure calls as well as function calls. Procedure calls
6079 -- are not frozen according to the rules (RM 13.14(14)) because it is
6080 -- impossible to have a procedure call to a non-frozen procedure in
6081 -- pure Ada, but in the code that we generate in the expander, this
6082 -- rule needs extending because we can generate procedure calls that
6083 -- need freezing.
6085 -- In Ada 2012, expression functions may be called within pre/post
6086 -- conditions of subsequent functions or expression functions. Such
6087 -- calls do not freeze when they appear within generated bodies,
6088 -- (including the body of another expression function) which would
6089 -- place the freeze node in the wrong scope. An expression function
6090 -- is frozen in the usual fashion, by the appearance of a real body,
6091 -- or at the end of a declarative part.
6094 and then not In_Spec_Expression
6096 and then
6099 then
6103 -- For a predefined operator, the type of the result is the type imposed
6104 -- by context, except for a predefined operation on universal fixed.
6105 -- Otherwise The type of the call is the type returned by the subprogram
6106 -- being called.
6113 -- If the subprogram returns an array type, and the context requires the
6114 -- component type of that array type, the node is really an indexing of
6115 -- the parameterless call. Resolve as such. A pathological case occurs
6116 -- when the type of the component is an access to the array type. In
6117 -- this case the call is truly ambiguous. If the call is to an intrinsic
6118 -- subprogram, it can't be an indexed component. This check is necessary
6119 -- because if it's Unchecked_Conversion, and we have "type T_Ptr is
6120 -- access T;" and "type T is array (...) of T_Ptr;" (i.e. an array of
6121 -- pointers to the same array), the compiler gets confused and does an
6122 -- infinite recursion.
6125 and then
6128 or else
6131 and then
6134 then
6135 declare
6140 begin
6143 then
6144 Error_Msg_N
6146 else
6149 -- The called entity may be an explicit dereference, in which
6150 -- case there is no entity to set.
6158 or else
6160 and then
6162 then
6165 -- Indexed call to a parameterless function
6167 Index_Node :=
6169 Prefix =>
6172 else
6173 -- An Ada 2005 prefixed call to a primitive operation
6174 -- whose first parameter is the prefix. This prefix was
6175 -- prepended to the parameter list, which is actually a
6176 -- list of indexes. Remove the prefix in order to build
6177 -- the proper indexed component.
6179 Index_Node :=
6181 Prefix =>
6184 Parameter_Associations =>
6185 New_List
6190 -- Preserve the parenthesis count of the node
6194 -- Since we are correcting a node classification error made
6195 -- by the parser, we call Replace rather than Rewrite.
6207 -- Annotate the tree by creating a call marker in case
6208 -- the original call is transformed by expansion. The call
6209 -- marker is automatically saved for later examination by
6210 -- the ABE Processing phase.
6219 else
6220 -- If the called function is not declared in the main unit and it
6221 -- returns the limited view of type then use the available view (as
6222 -- is done in Try_Object_Operation) to prevent back-end confusion;
6223 -- for the function entity itself. The call must appear in a context
6224 -- where the nonlimited view is available. If the function entity is
6225 -- in the extended main unit then no action is needed, because the
6226 -- back end handles this case. In either case the type of the call
6227 -- is the nonlimited view.
6231 then
6238 else
6243 -- In the case where the call is to an overloaded subprogram, Analyze
6244 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
6245 -- such a case Normalize_Actuals needs to be called once more to order
6246 -- the actuals correctly. Otherwise the call will have the ordering
6247 -- given by the last overloaded subprogram whether this is the correct
6248 -- one being called or not.
6255 -- In any case, call is fully resolved now. Reset Overload flag, to
6256 -- prevent subsequent overload resolution if node is analyzed again
6261 -- A Ghost entity must appear in a specific context
6267 -- If we are calling the current subprogram from immediately within its
6268 -- body, then that is the case where we can sometimes detect cases of
6269 -- infinite recursion statically. Do not try this in case restriction
6270 -- No_Recursion is in effect anyway, and do it only for source calls.
6275 -- Check violation of SPARK_05 restriction which does not permit
6276 -- a subprogram body to contain a call to the subprogram directly.
6280 then
6281 Check_SPARK_05_Restriction
6285 -- Issue warning for possible infinite recursion in the absence
6286 -- of the No_Recursion restriction.
6291 then
6292 -- Here we detected and flagged an infinite recursion, so we do
6293 -- not need to test the case below for further warnings. Also we
6294 -- are all done if we now have a raise SE node.
6300 -- If call is to immediately containing subprogram, then check for
6301 -- the case of a possible run-time detectable infinite recursion.
6303 else
6307 -- Although in general case, recursion is not statically
6308 -- checkable, the case of calling an immediately containing
6309 -- subprogram is easy to catch.
6313 -- If the recursive call is to a parameterless subprogram,
6314 -- then even if we can't statically detect infinite
6315 -- recursion, this is pretty suspicious, and we output a
6316 -- warning. Furthermore, we will try later to detect some
6317 -- cases here at run time by expanding checking code (see
6318 -- Detect_Infinite_Recursion in package Exp_Ch6).
6320 -- If the recursive call is within a handler, do not emit a
6321 -- warning, because this is a common idiom: loop until input
6322 -- is correct, catch illegal input in handler and restart.
6328 then
6329 -- For the case of a procedure call. We give the message
6330 -- only if the call is the first statement in a sequence
6331 -- of statements, or if all previous statements are
6332 -- simple assignments. This is simply a heuristic to
6333 -- decrease false positives, without losing too many good
6334 -- warnings. The idea is that these previous statements
6335 -- may affect global variables the procedure depends on.
6336 -- We also exclude raise statements, that may arise from
6337 -- constraint checks and are probably unrelated to the
6338 -- intended control flow.
6342 then
6343 declare
6345 begin
6349 N_Raise_Constraint_Error)
6350 then
6359 -- Do not give warning if we are in a conditional context
6361 declare
6363 begin
6369 then
6374 -- Here warning is to be issued
6390 -- Check obsolescent reference to Ada.Characters.Handling subprogram
6394 -- If subprogram name is a predefined operator, it was given in
6395 -- functional notation. Replace call node with operator node, so
6396 -- that actuals can be resolved appropriately.
6404 then
6410 -- Create a transient scope if the resulting type requires it
6412 -- There are several notable exceptions:
6414 -- a) In init procs, the transient scope overhead is not needed, and is
6415 -- even incorrect when the call is a nested initialization call for a
6416 -- component whose expansion may generate adjust calls. However, if the
6417 -- call is some other procedure call within an initialization procedure
6418 -- (for example a call to Create_Task in the init_proc of the task
6419 -- run-time record) a transient scope must be created around this call.
6421 -- b) Enumeration literal pseudo-calls need no transient scope
6423 -- c) Intrinsic subprograms (Unchecked_Conversion and source info
6424 -- functions) do not use the secondary stack even though the return
6425 -- type may be unconstrained.
6427 -- d) Calls to a build-in-place function, since such functions may
6428 -- allocate their result directly in a target object, and cases where
6429 -- the result does get allocated in the secondary stack are checked for
6430 -- within the specialized Exp_Ch6 procedures for expanding those
6431 -- build-in-place calls.
6433 -- e) Calls to inlinable expression functions do not use the secondary
6434 -- stack (since the call will be replaced by its returned object).
6436 -- f) If the subprogram is marked Inline_Always, then even if it returns
6437 -- an unconstrained type the call does not require use of the secondary
6438 -- stack. However, inlining will only take place if the body to inline
6439 -- is already present. It may not be available if e.g. the subprogram is
6440 -- declared in a child instance.
6442 -- If this is an initialization call for a type whose construction
6443 -- uses the secondary stack, and it is not a nested call to initialize
6444 -- a component, we do need to create a transient scope for it. We
6445 -- check for this by traversing the type in Check_Initialization_Call.
6451 then
6458 then
6461 elsif Expander_Active
6464 and then
6466 or else
6468 then
6471 -- If the call appears within the bounds of a loop, it will
6472 -- be rewritten and reanalyzed, nothing left to do here.
6479 and then not Within_Init_Proc
6480 then
6484 -- A protected function cannot be called within the definition of the
6485 -- enclosing protected type, unless it is part of a pre/postcondition
6486 -- on another protected operation. This may appear in the entry wrapper
6487 -- created for an entry with preconditions.
6492 and then not In_Spec_Expression
6494 then
6495 Error_Msg_NE
6499 -- Propagate interpretation to actuals, and add default expressions
6500 -- where needed.
6505 -- Overloaded literals are rewritten as function calls, for purpose of
6506 -- resolution. After resolution, we can replace the call with the
6507 -- literal itself.
6513 -- Avoid validation, since it is a static function call
6519 -- If the subprogram is not global, then kill all saved values and
6520 -- checks. This is a bit conservative, since in many cases we could do
6521 -- better, but it is not worth the effort. Similarly, we kill constant
6522 -- values. However we do not need to do this for internal entities
6523 -- (unless they are inherited user-defined subprograms), since they
6524 -- are not in the business of molesting local values.
6526 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
6527 -- kill all checks and values for calls to global subprograms. This
6528 -- takes care of the case where an access to a local subprogram is
6529 -- taken, and could be passed directly or indirectly and then called
6530 -- from almost any context.
6532 -- Note: we do not do this step till after resolving the actuals. That
6533 -- way we still take advantage of the current value information while
6534 -- scanning the actuals.
6536 -- We suppress killing values if we are processing the nodes associated
6537 -- with N_Freeze_Entity nodes. Otherwise the declaration of a tagged
6538 -- type kills all the values as part of analyzing the code that
6539 -- initializes the dispatch tables.
6543 or else Suppress_Value_Tracking_On_Call
6548 then
6549 Kill_Current_Values;
6552 -- If we are warning about unread OUT parameters, this is the place to
6553 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
6554 -- after the above call to Kill_Current_Values (since that call clears
6555 -- the Last_Assignment field of all local variables).
6560 then
6561 declare
6565 begin
6575 then
6585 -- If the subprogram is a primitive operation, check whether or not
6586 -- it is a correct dispatching call.
6590 then
6595 and then not In_Instance
6596 then
6600 -- If this is a dispatching call, generate the appropriate reference,
6601 -- for better source navigation in GPS.
6605 then
6608 -- Normal case, not a dispatching call: generate a call reference
6610 else
6618 -- Check for violation of restriction No_Specific_Termination_Handlers
6619 -- and warn on a potentially blocking call to Abort_Task.
6623 or else
6625 then
6632 -- A call to Ada.Real_Time.Timing_Events.Set_Handler to set a relative
6633 -- timing event violates restriction No_Relative_Delay (AI-0211). We
6634 -- need to check the second argument to determine whether it is an
6635 -- absolute or relative timing event.
6640 then
6644 -- Issue an error for a call to an eliminated subprogram. This routine
6645 -- will not perform the check if the call appears within a default
6646 -- expression.
6650 -- In formal mode, the primitive operations of a tagged type or type
6651 -- extension do not include functions that return the tagged type.
6657 then
6661 -- Implement rule in 12.5.1 (23.3/2): In an instance, if the actual is
6662 -- class-wide and the call dispatches on result in a context that does
6663 -- not provide a tag, the call raises Program_Error.
6666 and then In_Instance
6671 then
6672 -- Verify that none of the formals are controlling
6674 declare
6678 begin
6700 -- Check for calling a function with OUT or IN OUT parameter when the
6701 -- calling context (us right now) is not Ada 2012, so does not allow
6702 -- OUT or IN OUT parameters in function calls. Functions declared in
6703 -- a predefined unit are OK, as they may be called indirectly from a
6704 -- user-declared instantiation.
6710 then
6715 -- Check the dimensions of the actuals in the call. For function calls,
6716 -- propagate the dimensions from the returned type to N.
6720 -- All done, evaluate call and deal with elaboration issues
6728 -- Annotate the tree by creating a call marker in case the original call
6729 -- is transformed by expansion. The call marker is automatically saved
6730 -- for later examination by the ABE Processing phase.
6734 -- In GNATprove mode, expansion is disabled, but we want to inline some
6735 -- subprograms to facilitate formal verification. Indirect calls through
6736 -- a subprogram type or within a generic cannot be inlined. Inlining is
6737 -- performed only for calls subject to SPARK_Mode on.
6739 if GNATprove_Mode
6742 and then not Inside_A_Generic
6743 then
6750 -- Nothing to do if the subprogram is not eligible for inlining in
6751 -- GNATprove mode, or inlining is disabled with switch -gnatdm
6755 or else Debug_Flag_M
6756 then
6759 -- Calls cannot be inlined inside assertions, as GNATprove treats
6760 -- assertions as logic expressions. Only issue a message when the
6761 -- body has been seen, otherwise this leads to spurious messages
6762 -- on expression functions.
6766 Cannot_Inline
6770 -- Calls cannot be inlined inside default expressions
6773 Cannot_Inline
6776 -- Inlining should not be performed during pre-analysis
6780 -- Do not inline calls inside expression functions, as this
6781 -- would prevent interpreting them as logical formulas in
6782 -- GNATprove. Only issue a message when the body has been seen,
6783 -- otherwise this leads to spurious messages on callees that
6784 -- are themselves expression functions.
6787 and then Is_Expression_Function_Or_Completion
6789 then
6792 then
6793 Cannot_Inline
6798 -- With the one-pass inlining technique, a call cannot be
6799 -- inlined if the corresponding body has not been seen yet.
6802 Cannot_Inline
6805 -- Nothing to do if there is no body to inline, indicating that
6806 -- the subprogram is not suitable for inlining in GNATprove
6807 -- mode.
6812 -- Calls cannot be inlined inside potentially unevaluated
6813 -- expressions, as this would create complex actions inside
6814 -- expressions, that are not handled by GNATprove.
6817 Cannot_Inline
6821 -- Do not inline calls which would possibly lead to missing a
6822 -- type conversion check on an input parameter.
6825 Cannot_Inline
6829 -- Otherwise, inline the call
6831 else
6843 -----------------------------
6844 -- Resolve_Case_Expression --
6845 -----------------------------
6853 begin
6865 -- When the expression is of a scalar subtype different from the
6866 -- result subtype, then insert a conversion to ensure the generation
6867 -- of a constraint check.
6877 -- Apply RM 4.5.7 (17/3): whether the expression is statically or
6878 -- dynamically tagged must be known statically.
6886 Error_Msg_N
6900 -------------------------------
6901 -- Resolve_Character_Literal --
6902 -------------------------------
6908 begin
6909 -- Verify that the character does belong to the type of the context
6914 -- Wide_Wide_Character literals must always be defined, since the set
6915 -- of wide wide character literals is complete, i.e. if a character
6916 -- literal is accepted by the parser, then it is OK for wide wide
6917 -- character (out of range character literals are rejected).
6922 -- Always accept character literal for type Any_Character, which
6923 -- occurs in error situations and in comparisons of literals, both
6924 -- of which should accept all literals.
6929 -- For Standard.Character or a type derived from it, check that the
6930 -- literal is in range.
6937 -- For Standard.Wide_Character or a type derived from it, check that the
6938 -- literal is in range.
6945 -- If the entity is already set, this has already been resolved in a
6946 -- generic context, or comes from expansion. Nothing else to do.
6951 -- Otherwise we have a user defined character type, and we can use the
6952 -- standard visibility mechanisms to locate the referenced entity.
6954 else
6967 -- If we fall through, then the literal does not match any of the
6968 -- entries of the enumeration type. This isn't just a constraint error
6969 -- situation, it is an illegality (see RM 4.2).
6971 Error_Msg_NE
6975 ---------------------------
6976 -- Resolve_Comparison_Op --
6977 ---------------------------
6979 -- Context requires a boolean type, and plays no role in resolution.
6980 -- Processing identical to that for equality operators. The result type is
6981 -- the base type, which matters when pathological subtypes of booleans with
6982 -- limited ranges are used.
6989 begin
6990 -- If this is an intrinsic operation which is not predefined, use the
6991 -- types of its declared arguments to resolve the possibly overloaded
6992 -- operands. Otherwise the operands are unambiguous and specify the
6993 -- expected type.
6998 else
7009 -- Skip remaining processing if already set to Any_Type
7015 -- Deal with other error cases
7019 T = Any_Character
7020 then
7023 else
7031 -- Resolve the operands if types OK
7040 -- In SPARK, ordering operators <, <=, >, >= are not defined for Boolean
7041 -- types or array types except String.
7044 Check_SPARK_05_Restriction
7049 then
7050 Check_SPARK_05_Restriction
7054 -- Check comparison on unordered enumeration
7058 Error_Msg_NE
7065 -- Evaluate the relation (note we do this after the above check since
7066 -- this Eval call may change N to True/False. Skip this evaluation
7067 -- inside assertions, in order to keep assertions as written by users
7068 -- for tools that rely on these, e.g. GNATprove for loop invariants.
7069 -- Except evaluation is still performed even inside assertions for
7070 -- comparisons between values of universal type, which are useless
7071 -- for static analysis tools, and not supported even by GNATprove.
7075 and then
7077 then
7082 -----------------------------------------
7083 -- Resolve_Discrete_Subtype_Indication --
7084 -----------------------------------------
7086 procedure Resolve_Discrete_Subtype_Indication
7089 is
7093 begin
7101 else
7111 Error_Msg_NE
7114 -- Rewrite the constraint as a range of Typ
7115 -- to allow compilation to proceed further.
7127 else
7131 -- Additionally, we must check that the bounds are compatible
7132 -- with the given subtype, which might be different from the
7133 -- type of the context.
7137 -- ??? If the above check statically detects a Constraint_Error
7138 -- it replaces the offending bound(s) of the range R with a
7139 -- Constraint_Error node. When the itype which uses these bounds
7140 -- is frozen the resulting call to Duplicate_Subexpr generates
7141 -- a new temporary for the bounds.
7143 -- Unfortunately there are other itypes that are also made depend
7144 -- on these bounds, so when Duplicate_Subexpr is called they get
7145 -- a forward reference to the newly created temporaries and Gigi
7146 -- aborts on such forward references. This is probably sign of a
7147 -- more fundamental problem somewhere else in either the order of
7148 -- itype freezing or the way certain itypes are constructed.
7150 -- To get around this problem we call Remove_Side_Effects right
7151 -- away if either bounds of R are a Constraint_Error.
7153 declare
7157 begin
7173 -------------------------
7174 -- Resolve_Entity_Name --
7175 -------------------------
7177 -- Used to resolve identifiers and expanded names
7180 function Is_Assignment_Or_Object_Expression
7183 -- Determine whether node Context denotes an assignment statement or an
7184 -- object declaration whose expression is node Expr.
7186 ----------------------------------------
7187 -- Is_Assignment_Or_Object_Expression --
7188 ----------------------------------------
7190 function Is_Assignment_Or_Object_Expression
7193 is
7194 begin
7196 N_Object_Declaration)
7198 then
7201 -- Check whether a construct that yields a name is the expression of
7202 -- an assignment statement or an object declaration.
7205 N_Explicit_Dereference,
7206 N_Indexed_Component,
7207 N_Selected_Component,
7208 N_Slice)
7210 or else
7212 N_Unchecked_Type_Conversion)
7214 then
7215 return
7216 Is_Assignment_Or_Object_Expression
7220 -- Otherwise the context is not an assignment statement or an object
7221 -- declaration.
7223 else
7228 -- Local variables
7233 -- Start of processing for Resolve_Entity_Name
7235 begin
7236 -- If garbage from errors, set to Any_Type and return
7243 -- Replace named numbers by corresponding literals. Note that this is
7244 -- the one case where Resolve_Entity_Name must reset the Etype, since
7245 -- it is currently marked as universal.
7255 -- For enumeration literals, we need to make sure that a proper style
7256 -- check is done, since such literals are overloaded, and thus we did
7257 -- not do a style check during the first phase of analysis.
7263 -- Case of (sub)type name appearing in a context where an expression
7264 -- is expected. This is legal if occurrence is a current instance.
7265 -- See RM 8.6 (17/3).
7271 -- Any other use is an error
7273 else
7274 Error_Msg_N
7278 -- Check discriminant use if entity is discriminant in current scope,
7279 -- i.e. discriminant of record or concurrent type currently being
7280 -- analyzed. Uses in corresponding body are unrestricted.
7285 then
7288 -- A parameterless generic function cannot appear in a context that
7289 -- requires resolution.
7294 -- In Ada 83 an OUT parameter cannot be read, but attributes of
7295 -- array types (i.e. bounds and length) are legal.
7303 or else Is_Assignment_Or_Object_Expression
7306 then
7311 -- In all other cases, just do the possible static evaluation
7313 else
7314 -- A deferred constant that appears in an expression must have a
7315 -- completion, unless it has been removed by in-place expansion of
7316 -- an aggregate. A constant that is a renaming does not need
7317 -- initialization.
7323 and then not In_Spec_Expression
7326 then
7330 then
7332 else
7333 Error_Msg_N
7343 -- When the entity appears in a parameter association, retrieve the
7344 -- related subprogram call.
7352 -- The following checks are only relevant when SPARK_Mode is on as
7353 -- they are not standard Ada legality rules.
7357 -- An effectively volatile object subject to enabled properties
7358 -- Async_Writers or Effective_Reads must appear in non-interfering
7359 -- context (SPARK RM 7.1.3(12)).
7366 then
7367 SPARK_Msg_N
7372 -- Check for possible elaboration issues with respect to reads of
7373 -- variables. The act of renaming the variable is not considered a
7374 -- read as it simply establishes an alias.
7376 if Legacy_Elaboration_Checks
7378 and then Dynamic_Elaboration_Checks
7380 then
7384 -- The variable may eventually become a constituent of a single
7385 -- protected/task type. Record the reference now and verify its
7386 -- legality when analyzing the contract of the variable
7387 -- (SPARK RM 9.3).
7394 -- A Ghost entity must appear in a specific context
7404 -------------------
7405 -- Resolve_Entry --
7406 -------------------
7418 -- If the bounds of the entry family being called depend on task
7419 -- discriminants, build a new index subtype where a discriminant is
7420 -- replaced with the value of the discriminant of the target task.
7421 -- The target task is the prefix of the entry name in the call.
7423 -----------------------
7424 -- Actual_Index_Type --
7425 -----------------------
7435 -- If the bound is given by a discriminant, replace with a reference
7436 -- to the discriminant of the same name in the target task. If the
7437 -- entry name is the target of a requeue statement and the entry is
7438 -- in the current protected object, the bound to be used is the
7439 -- discriminal of the object (see Apply_Range_Checks for details of
7440 -- the transformation).
7442 -----------------------------
7443 -- Actual_Discriminant_Ref --
7444 -----------------------------
7450 begin
7455 then
7461 then
7462 -- Note: here Bound denotes a discriminant of the corresponding
7463 -- record type tskV, whose discriminal is a formal of the
7464 -- init-proc tskVIP. What we want is the body discriminal,
7465 -- which is associated to the discriminant of the original
7466 -- concurrent type tsk.
7468 return New_Occurrence_Of
7471 else
7472 Ref :=
7482 -- Start of processing for Actual_Index_Type
7484 begin
7487 then
7490 else
7504 -- Start of processing for Resolve_Entry
7506 begin
7507 -- Find name of entry being called, and resolve prefix of name with its
7508 -- own type. The prefix can be overloaded, and the name and signature of
7509 -- the entry must be taken into account.
7513 -- Case of dealing with entry family within the current tasks
7517 else
7523 -- Entry call to an entry (or entry family) in the current task. This
7524 -- is legal even though the task will deadlock. Rewrite as call to
7525 -- current task.
7527 -- This can also be a call to an entry in an enclosing task. If this
7528 -- is a single task, we have to retrieve its name, because the scope
7529 -- of the entry is the task type, not the object. If the enclosing
7530 -- task is a task type, the identity of the task is given by its own
7531 -- self variable.
7533 -- Finally this can be a requeue on an entry of the same task or
7534 -- protected object.
7541 then
7542 -- S is an enclosing task or protected object. The concurrent
7543 -- declaration has been converted into a type declaration, and
7544 -- the object itself has an object declaration that follows
7545 -- the type in the same declarative part.
7557 -- Call to current task. Will be transformed into call to Self
7564 New_N :=
7567 Selector_Name =>
7574 then
7575 -- Use the entry name (which must be unique at this point) to find
7576 -- the prefix that returns the corresponding task/protected type.
7578 declare
7584 begin
7606 -- Generate a reference for the index when it denotes an entity
7612 -- Up to this point the expression could have been the actual in a
7613 -- simple entry call, and be given by a named association.
7617 else
7623 ------------------------
7624 -- Resolve_Entry_Call --
7625 ------------------------
7636 begin
7637 -- We kill all checks here, because it does not seem worth the effort to
7638 -- do anything better, an entry call is a big operation.
7640 Kill_All_Checks;
7642 -- Processing of the name is similar for entry calls and protected
7643 -- operation calls. Once the entity is determined, we can complete
7644 -- the resolution of the actuals.
7646 -- The selector may be overloaded, in the case of a protected object
7647 -- with overloaded functions. The type of the context is used for
7648 -- resolution.
7653 then
7654 declare
7658 begin
7677 -- Simple entry or protected operation call
7690 -- Call to member of entry family
7697 -- We cannot in general check the maximum depth of protected entry calls
7698 -- at compile time. But we can tell that any protected entry call at all
7699 -- violates a specified nesting depth of zero.
7705 -- Use context type to disambiguate a protected function that can be
7706 -- called without actuals and that returns an array type, and where the
7707 -- argument list may be an indexing of the returned value.
7712 and then
7718 and then
7719 Covers
7722 then
7723 declare
7726 begin
7727 Index_Node :=
7729 Prefix =>
7733 -- Since we are correcting a node classification error made by the
7734 -- parser, we call Replace rather than Rewrite.
7747 then
7748 -- Note the entity being called before rewriting the call, so that
7749 -- it appears used at this point.
7753 -- Rewrite as call to the precondition wrapper, adding the task
7754 -- object to the list of actuals. If the call is to a member of an
7755 -- entry family, include the index as well.
7757 declare
7761 begin
7770 New_Call :=
7772 Name =>
7777 -- Preanalyze and resolve new call. Current procedure is called
7778 -- from Resolve_Call, after which expansion will take place.
7785 -- The operation name may have been overloaded. Order the actuals
7786 -- according to the formals of the resolved entity, and set the return
7787 -- type to that of the operation.
7794 -- Reset the Is_Overloaded flag, since resolution is now completed
7796 -- Simple entry call
7801 -- Call to a member of an entry family
7811 -- Create a call reference to the entry
7819 -- Verify that a procedure call cannot masquerade as an entry
7820 -- call where an entry call is expected.
7825 then
7830 then
7835 then
7840 -- After resolution, entry calls and protected procedure calls are
7841 -- changed into entry calls, for expansion. The structure of the node
7842 -- does not change, so it can safely be done in place. Protected
7843 -- function calls must keep their structure because they are
7844 -- subexpressions.
7848 -- A protected operation that is not a function may modify the
7849 -- corresponding object, and cannot apply to a constant. If this
7850 -- is an internal call, the prefix is the type itself.
7856 then
7857 Error_Msg_N
7859 Entry_Name);
7862 declare
7865 begin
7866 Entry_Call :=
7871 -- Inherit relevant attributes from the original call
7873 Set_First_Named_Actual
7876 Set_Is_Elaboration_Checks_OK_Node
7879 Set_Is_Elaboration_Warnings_OK_Node
7882 Set_Is_SPARK_Mode_On_Node
7889 -- Protected functions can return on the secondary stack, in which
7890 -- case we must trigger the transient scope mechanism.
7892 elsif Expander_Active
7894 then
7899 -------------------------
7900 -- Resolve_Equality_Op --
7901 -------------------------
7903 -- Both arguments must have the same type, and the boolean context does
7904 -- not participate in the resolution. The first pass verifies that the
7905 -- interpretation is not ambiguous, and the type of the left argument is
7906 -- correctly set, or is Any_Type in case of ambiguity. If both arguments
7907 -- are strings or aggregates, allocators, or Null, they are ambiguous even
7908 -- though they carry a single (universal) type. Diagnose this case here.
7916 -- The resolution rule for if expressions requires that each such must
7917 -- have a unique type. This means that if several dependent expressions
7918 -- are of a non-null anonymous access type, and the context does not
7919 -- impose an expected type (as can be the case in an equality operation)
7920 -- the expression must be rejected.
7923 -- Attempt to explain the nature of a redundant comparison with True. If
7924 -- the expression N is too complex, this routine issues a general error
7925 -- message.
7928 -- In the case of allocators and access attributes, the context must
7929 -- provide an indication of the specific access type to be used. If
7930 -- one operand is of such a "generic" access type, check whether there
7931 -- is a specific visible access type that has the same designated type.
7932 -- This is semantically dubious, and of no interest to any real code,
7933 -- but c48008a makes it all worthwhile.
7935 -------------------------
7936 -- Check_If_Expression --
7937 -------------------------
7943 begin
7950 then
7956 ------------------------
7957 -- Explain_Redundancy --
7958 ------------------------
7965 begin
7968 -- Strip the operand down to an entity
7970 loop
7973 else
7978 -- The construct denotes an entity
7983 -- Do not generate an error message when the comparison is done
7984 -- against the enumeration literal Standard.True.
7988 -- Build a customized error message
8015 -- The construct is too complex to disect, issue a general message
8017 else
8022 -----------------------------
8023 -- Find_Unique_Access_Type --
8024 -----------------------------
8031 begin
8033 E_Access_Attribute_Type)
8034 then
8038 E_Access_Attribute_Type)
8039 then
8041 else
8053 then
8066 -- Start of processing for Resolve_Equality_Op
8068 begin
8079 T = Any_Character
8080 then
8083 else
8092 then
8101 -- If expressions must have a single type, and if the context does
8102 -- not impose one the dependent expressions cannot be anonymous
8103 -- access types.
8105 -- Why no similar processing for case expressions???
8109 E_Anonymous_Access_Subprogram_Type)
8111 E_Anonymous_Access_Subprogram_Type)
8112 then
8120 -- In SPARK, equality operators = and /= for array types other than
8121 -- String are only defined when, for each index position, the
8122 -- operands have equal static bounds.
8126 -- Protect call to Matching_Static_Array_Bounds to avoid costly
8127 -- operation if not needed.
8135 then
8136 Check_SPARK_05_Restriction
8141 -- If the unique type is a class-wide type then it will be expanded
8142 -- into a dispatching call to the predefined primitive. Therefore we
8143 -- check here for potential violation of such restriction.
8149 -- Only warn for redundant equality comparison to True for objects
8150 -- (e.g. "X = True") and operations (e.g. "(X < Y) = True"). For
8151 -- other expressions, it may be a matter of preference to write
8152 -- "Expr = True" or "Expr".
8154 if Warn_On_Redundant_Constructs
8159 and then
8161 or else
8163 then
8164 Error_Msg_N -- CODEFIX
8174 -- If this is an inequality, it may be the implicit inequality
8175 -- created for a user-defined operation, in which case the corres-
8176 -- ponding equality operation is not intrinsic, and the operation
8177 -- cannot be constant-folded. Else fold.
8182 or else Is_Intrinsic_Subprogram
8184 then
8190 then
8194 -- Ada 2005: If one operand is an anonymous access type, convert the
8195 -- other operand to it, to ensure that the underlying types match in
8196 -- the back-end. Same for access_to_subprogram, and the conversion
8197 -- verifies that the types are subtype conformant.
8199 -- We apply the same conversion in the case one of the operands is a
8200 -- private subtype of the type of the other.
8202 -- Why the Expander_Active test here ???
8204 if Expander_Active
8205 and then
8207 E_Anonymous_Access_Subprogram_Type)
8209 then
8229 ----------------------------------
8230 -- Resolve_Explicit_Dereference --
8231 ----------------------------------
8239 -- The candidate prefix type, if overloaded
8244 begin
8248 -- A useful optimization: check whether the dereference denotes an
8249 -- element of a container, and if so rewrite it as a call to the
8250 -- corresponding Element function.
8252 -- Disabled for now, on advice of ARG. A more restricted form of the
8253 -- predicate might be acceptable ???
8255 -- if Is_Container_Element (N) then
8256 -- return;
8257 -- end if;
8261 -- Use the context type to select the prefix that has the correct
8262 -- designated type. Keep the first match, which will be the inner-
8263 -- most.
8270 then
8275 -- Remove access types that do not match, but preserve access
8276 -- to subprogram interpretations, in case a further dereference
8277 -- is needed (see below).
8290 else
8291 -- If no interpretation covers the designated type of the prefix,
8292 -- this is the pathological case where not all implementations of
8293 -- the prefix allow the interpretation of the node as a call. Now
8294 -- that the expected type is known, Remove other interpretations
8295 -- from prefix, rewrite it as a call, and resolve again, so that
8296 -- the proper call node is generated.
8307 New_N :=
8309 Name =>
8320 -- If not overloaded, resolve P with its own type
8322 else
8326 -- If the prefix might be null, add an access check
8330 then
8334 -- If the designated type is a packed unconstrained array type, and the
8335 -- explicit dereference is not in the context of an attribute reference,
8336 -- then we must compute and set the actual subtype, since it is needed
8337 -- by Gigi. The reason we exclude the attribute case is that this is
8338 -- handled fine by Gigi, and in fact we use such attributes to build the
8339 -- actual subtype. We also exclude generated code (which builds actual
8340 -- subtypes directly if they are needed).
8347 then
8353 -- Note: No Eval processing is required for an explicit dereference,
8354 -- because such a name can never be static.
8358 -------------------------------------
8359 -- Resolve_Expression_With_Actions --
8360 -------------------------------------
8363 begin
8366 -- If N has no actions, and its expression has been constant folded,
8367 -- then rewrite N as just its expression. Note, we can't do this in
8368 -- the general case of Is_Empty_List (Actions (N)) as this would cause
8369 -- Expression (N) to be expanded again.
8373 then
8378 ----------------------------------
8379 -- Resolve_Generalized_Indexing --
8380 ----------------------------------
8388 begin
8389 -- In ASIS mode, propagate the information about the indexes back to
8390 -- to the original indexing node. The generalized indexing is either
8391 -- a function call, or a dereference of one. The actuals include the
8392 -- prefix of the original node, which is the container expression.
8401 loop
8410 -- If expression is to be reanalyzed, reset Generalized_Indexing
8411 -- to recreate call node, as is the case when the expression is
8412 -- part of an expression function.
8421 else
8427 ---------------------------
8428 -- Resolve_If_Expression --
8429 ---------------------------
8438 begin
8439 -- Defend against malformed expressions
8457 -- When the "then" expression is of a scalar subtype different from the
8458 -- result subtype, then insert a conversion to ensure the generation of
8459 -- a constraint check. The same is done for the else part below, again
8460 -- comparing subtypes rather than base types.
8467 -- If ELSE expression present, just resolve using the determined type
8468 -- If type is universal, resolve to any member of the class.
8477 else
8487 -- Apply RM 4.5.7 (17/3): whether the expression is statically or
8488 -- dynamically tagged must be known statically.
8493 then
8499 -- If no ELSE expression is present, root type must be Standard.Boolean
8500 -- and we provide a Standard.True result converted to the appropriate
8501 -- Boolean type (in case it is a derived boolean type).
8504 Else_Expr :=
8509 else
8523 -------------------------------
8524 -- Resolve_Indexed_Component --
8525 -------------------------------
8533 begin
8541 -- Use the context type to select the prefix that yields the correct
8542 -- component type.
8544 declare
8551 begin
8558 and then
8559 Covers
8562 then
8571 else
8577 else
8588 else
8595 -- If prefix is access type, dereference to get real array type.
8596 -- Note: we do not apply an access check because the expander always
8597 -- introduces an explicit dereference, and the check will happen there.
8603 -- If name was overloaded, set component type correctly now
8604 -- If a misplaced call to an entry family (which has no index types)
8605 -- return. Error will be diagnosed from calling context.
8609 else
8616 -- The prefix may have resolved to a string literal, in which case its
8617 -- etype has a special representation. This is only possible currently
8618 -- if the prefix is a static concatenation, written in functional
8619 -- notation.
8624 else
8631 else
8642 -- Do not generate the warning on suspicious index if we are analyzing
8643 -- package Ada.Tags; otherwise we will report the warning with the
8644 -- Prims_Ptr field of the dispatch table.
8647 or else not
8649 Ada_Tags)
8650 then
8655 -- If the array type is atomic, and the component is not atomic, then
8656 -- this is worth a warning, since we have a situation where the access
8657 -- to the component may cause extra read/writes of the atomic array
8658 -- object, or partial word accesses, which could be unexpected.
8664 and then Has_Atomic_Components
8667 then
8668 Error_Msg_N
8670 Error_Msg_N
8675 -----------------------------
8676 -- Resolve_Integer_Literal --
8677 -----------------------------
8680 begin
8685 --------------------------------
8686 -- Resolve_Intrinsic_Operator --
8687 --------------------------------
8696 -- If the operand is a literal, it cannot be the expression in a
8697 -- conversion. Use a qualified expression instead.
8699 ---------------------
8700 -- Convert_Operand --
8701 ---------------------
8707 begin
8709 Res :=
8715 else
8722 -- Start of processing for Resolve_Intrinsic_Operator
8724 begin
8725 -- We must preserve the original entity in a generic setting, so that
8726 -- the legality of the operation can be verified in an instance.
8741 -- If the result or operand types are private, rewrite with unchecked
8742 -- conversions on the operands and the result, to expose the proper
8743 -- underlying numeric type.
8748 then
8753 else
8774 then
8775 -- Add explicit conversion where needed, and save interpretations in
8776 -- case operands are overloaded.
8783 else
8789 else
8799 else
8804 --------------------------------------
8805 -- Resolve_Intrinsic_Unary_Operator --
8806 --------------------------------------
8808 procedure Resolve_Intrinsic_Unary_Operator
8811 is
8816 begin
8835 else
8840 ------------------------
8841 -- Resolve_Logical_Op --
8842 ------------------------
8847 begin
8850 -- Predefined operations on scalar types yield the base type. On the
8851 -- other hand, logical operations on arrays yield the type of the
8852 -- arguments (and the context).
8856 else
8860 -- The following test is required because the operands of the operation
8861 -- may be literals, in which case the resulting type appears to be
8862 -- compatible with a signed integer type, when in fact it is compatible
8863 -- only with modular types. If the context itself is universal, the
8864 -- operation is illegal.
8872 Error_Msg_N
8880 then
8884 -- Replace AND by AND THEN, or OR by OR ELSE, if Short_Circuit_And_Or
8885 -- is active and the result type is standard Boolean (do not mess with
8886 -- ops that return a nonstandard Boolean type, because something strange
8887 -- is going on).
8889 -- Note: you might expect this replacement to be done during expansion,
8890 -- but that doesn't work, because when the pragma Short_Circuit_And_Or
8891 -- is used, no part of the right operand of an "and" or "or" operator
8892 -- should be executed if the left operand would short-circuit the
8893 -- evaluation of the corresponding "and then" or "or else". If we left
8894 -- the replacement to expansion time, then run-time checks associated
8895 -- with such operands would be evaluated unconditionally, due to being
8896 -- before the condition prior to the rewriting as short-circuit forms
8897 -- during expansion.
8899 if Short_Circuit_And_Or
8902 then
8903 -- Mark the corresponding putative SCO operator as truly a logical
8904 -- (and short-circuit) operator.
8917 -- Case of OR changed to OR ELSE
8919 else
8927 -- Return now, since analysis of the rewritten ops will take care of
8928 -- other reference bookkeeping and expression folding.
8943 -- In SPARK, logical operations AND, OR and XOR for arrays are defined
8944 -- only when both operands have same static lower and higher bounds. Of
8945 -- course the types have to match, so only check if operands are
8946 -- compatible and the node itself has no errors.
8950 then
8951 declare
8955 begin
8956 -- Protect call to Matching_Static_Array_Bounds to avoid costly
8957 -- operation if not needed.
8964 then
8965 Check_SPARK_05_Restriction
8972 ---------------------------
8973 -- Resolve_Membership_Op --
8974 ---------------------------
8976 -- The context can only be a boolean type, and does not determine the
8977 -- arguments. Arguments should be unambiguous, but the preference rule for
8978 -- universal types applies.
8988 -- Analysis has determined a unique type for the left operand. Use it to
8989 -- resolve the disjuncts.
8991 ----------------------------
8992 -- Resolve_Set_Membership --
8993 ----------------------------
8999 begin
9000 -- If the left operand is overloaded, find type compatible with not
9001 -- overloaded alternative of the right operand.
9010 else
9015 -- Unclear how to resolve expression if all alternatives are also
9016 -- overloaded.
9022 else
9031 -- Alternative is an expression, a range
9032 -- or a subtype mark.
9036 then
9043 -- Check for duplicates for discrete case
9046 declare
9055 begin
9056 -- Loop checking duplicates. This is quadratic, but giant sets
9057 -- are unlikely in this context so it's a reasonable choice.
9064 N_Character_Literal)
9066 then
9084 -- Start of processing for Resolve_Membership_Op
9086 begin
9092 Resolve_Set_Membership;
9096 and then
9098 or else
9101 then
9104 -- Ada 2005 (AI-251): Support the following case:
9106 -- type I is interface;
9107 -- type T is tagged ...
9109 -- function Test (O : I'Class) is
9110 -- begin
9111 -- return O in T'Class.
9112 -- end Test;
9114 -- In this case we have nothing else to do. The membership test will be
9115 -- done at run time.
9122 then
9124 else
9128 -- If mixed-mode operations are present and operands are all literal,
9129 -- the only interpretation involves Duration, which is probably not
9130 -- the intention of the programmer.
9145 then
9151 else
9156 -- Here after resolving membership operation
9163 ------------------
9164 -- Resolve_Null --
9165 ------------------
9170 begin
9171 -- Handle restriction against anonymous null access values This
9172 -- restriction can be turned off using -gnatdj.
9174 -- Ada 2005 (AI-231): Remove restriction
9177 and then not Debug_Flag_J
9180 then
9181 -- In the common case of a call which uses an explicitly null value
9182 -- for an access parameter, give specialized error message.
9185 Error_Msg_N
9188 -- Standard message for all other cases (are there any?)
9190 else
9191 Error_Msg_N
9196 -- Ada 2005 (AI-231): Generate the null-excluding check in case of
9197 -- assignment to a null-excluding object
9202 then
9204 Insert_Action
9209 else
9216 -- In a distributed context, null for a remote access to subprogram may
9217 -- need to be replaced with a special record aggregate. In this case,
9218 -- return after having done the transformation.
9223 then
9227 -- The null literal takes its type from the context
9232 -----------------------
9233 -- Resolve_Op_Concat --
9234 -----------------------
9238 -- We wish to avoid deep recursion, because concatenations are often
9239 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
9240 -- operands nonrecursively until we find something that is not a simple
9241 -- concatenation (A in this case). We resolve that, and then walk back
9242 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
9243 -- to do the rest of the work at each level. The Parent pointers allow
9244 -- us to avoid recursion, and thus avoid running out of memory. See also
9245 -- Sem_Ch4.Analyze_Concatenation, where a similar approach is used.
9250 begin
9251 -- The following code is equivalent to:
9253 -- Resolve_Op_Concat_First (NN, Typ);
9254 -- Resolve_Op_Concat_Arg (N, ...);
9255 -- Resolve_Op_Concat_Rest (N, Typ);
9257 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
9258 -- operand is a concatenation.
9260 -- Walk down left operands
9262 loop
9271 -- Now (given the above example) NN is A&B and Op1 is A
9273 -- First resolve Op1 ...
9277 -- ... then walk NN back up until we reach N (where we started), calling
9278 -- Resolve_Op_Concat_Rest along the way.
9280 loop
9287 Check_SPARK_05_Restriction
9292 ---------------------------
9293 -- Resolve_Op_Concat_Arg --
9294 ---------------------------
9296 procedure Resolve_Op_Concat_Arg
9301 is
9305 begin
9307 if Is_Comp
9311 then
9313 else
9317 -- If both Array & Array and Array & Component are visible, there is a
9318 -- potential ambiguity that must be reported.
9323 then
9327 -- If the operation is user-defined and not overloaded use its
9328 -- profile. The operation may be a renaming, in which case it has
9329 -- been rewritten, and we want the original profile.
9334 then
9336 Etype
9340 -- Otherwise an aggregate may match both the array type and the
9341 -- component type.
9343 else
9348 else
9352 then
9353 declare
9358 begin
9363 -- Special-case the error message when the overloading is
9364 -- caused by a function that yields an array and can be
9365 -- called without parameters.
9370 Error_Msg_NE
9372 Error_Msg_NE
9376 else
9384 or else
9386 then
9387 Error_Msg_N -- CODEFIX
9405 else
9410 else
9414 -- Concatenation is restricted in SPARK: each operand must be either a
9415 -- string literal, the name of a string constant, a static character or
9416 -- string expression, or another concatenation. Arg cannot be a
9417 -- concatenation here as callers of Resolve_Op_Concat_Arg call it
9418 -- separately on each final operand, past concatenation operations.
9422 Check_SPARK_05_Restriction
9430 then
9431 Check_SPARK_05_Restriction
9435 -- Do not issue error on an operand that is neither a character nor a
9436 -- string, as the error is issued in Resolve_Op_Concat.
9438 else
9445 -----------------------------
9446 -- Resolve_Op_Concat_First --
9447 -----------------------------
9454 begin
9455 -- The parser folds an enormous sequence of concatenations of string
9456 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
9457 -- in the right operand. If the expression resolves to a predefined "&"
9458 -- operator, all is well. Otherwise, the parser's folding is wrong, so
9459 -- we give an error. See P_Simple_Expression in Par.Ch4.
9464 then
9479 ----------------------------
9480 -- Resolve_Op_Concat_Rest --
9481 ----------------------------
9487 begin
9496 -- If this is not a static concatenation, but the result is a string
9497 -- type (and not an array of strings) ensure that static string operands
9498 -- have their subtypes properly constructed.
9502 then
9508 ----------------------
9509 -- Resolve_Op_Expon --
9510 ----------------------
9515 begin
9516 -- Catch attempts to do fixed-point exponentiation with universal
9517 -- operands, which is a case where the illegality is not caught during
9518 -- normal operator analysis. This is not done in preanalysis mode
9519 -- since the tree is not fully decorated during preanalysis.
9531 then
9541 then
9548 then
9552 -- We do the resolution using the base type, because intermediate values
9553 -- in expressions are always of the base type, not a subtype of it.
9558 -- For integer types, right argument must be in Natural range
9573 -- Evaluate the exponentiation operator for dimensioned type
9576 else
9580 -- Set overflow checking bit. Much cleverer code needed here eventually
9581 -- and perhaps the Resolve routines should be separated for the various
9582 -- arithmetic operations, since they will need different processing. ???
9591 --------------------
9592 -- Resolve_Op_Not --
9593 --------------------
9599 -- This function determines if the parent node is a boolean operator or
9600 -- operation (comparison op, membership test, or short circuit form) and
9601 -- the not in question is the left operand of this operation. Note that
9602 -- if the not is in parens, then false is returned.
9604 -----------------------
9605 -- Parent_Is_Boolean --
9606 -----------------------
9609 begin
9613 else
9615 when N_And_Then
9616 | N_In
9617 | N_Not_In
9618 | N_Op_And
9619 | N_Op_Eq
9620 | N_Op_Ge
9621 | N_Op_Gt
9622 | N_Op_Le
9623 | N_Op_Lt
9624 | N_Op_Ne
9625 | N_Op_Or
9626 | N_Op_Xor
9627 | N_Or_Else
9628 =>
9637 -- Start of processing for Resolve_Op_Not
9639 begin
9640 -- Predefined operations on scalar types yield the base type. On the
9641 -- other hand, logical operations on arrays yield the type of the
9642 -- arguments (and the context).
9646 else
9650 -- Straightforward case of incorrect arguments
9657 -- Special case of probable missing parens
9661 Error_Msg_N
9664 else
9665 Error_Msg_N
9672 -- OK resolution of NOT
9674 else
9675 -- Warn if non-boolean types involved. This is a case like not a < b
9676 -- where a and b are modular, where we will get (not a) < b and most
9677 -- likely not (a < b) was intended.
9679 if Warn_On_Questionable_Missing_Parens
9681 and then Parent_Is_Boolean
9682 then
9686 -- Warn on double negation if checking redundant constructs
9688 if Warn_On_Redundant_Constructs
9693 then
9697 -- Complete resolution and evaluation of NOT
9707 -----------------------------
9708 -- Resolve_Operator_Symbol --
9709 -----------------------------
9711 -- Nothing to be done, all resolved already
9717 begin
9721 ----------------------------------
9722 -- Resolve_Qualified_Expression --
9723 ----------------------------------
9731 begin
9734 -- Protect call to Matching_Static_Array_Bounds to avoid costly
9735 -- operation if not needed.
9742 then
9743 Check_SPARK_05_Restriction
9747 -- A qualified expression requires an exact match of the type, class-
9748 -- wide matching is not allowed. However, if the qualifying type is
9749 -- specific and the expression has a class-wide type, it may still be
9750 -- okay, since it can be the result of the expansion of a call to a
9751 -- dispatching function, so we also have to check class-wideness of the
9752 -- type of the expression's original node.
9755 or else
9759 then
9763 -- If the target type is unconstrained, then we reset the type of the
9764 -- result from the type of the expression. For other cases, the actual
9765 -- subtype of the expression is the target type.
9769 then
9776 -- If we still have a qualified expression after the static evaluation,
9777 -- then apply a scalar range check if needed. The reason that we do this
9778 -- after the Eval call is that otherwise, the application of the range
9779 -- check may convert an illegal static expression and result in warning
9780 -- rather than giving an error (e.g Integer'(Integer'Last + 1)).
9786 -- Finally, check whether a predicate applies to the target type. This
9787 -- comes from AI12-0100. As for type conversions, check the enclosing
9788 -- context to prevent an infinite expansion.
9794 or else
9796 then
9799 -- In the case of a qualified expression in an allocator, the check
9800 -- is applied when expanding the allocator, so avoid redundant check.
9804 then
9810 ------------------------------
9811 -- Resolve_Raise_Expression --
9812 ------------------------------
9815 begin
9819 else
9824 -------------------
9825 -- Resolve_Range --
9826 -------------------
9833 -- Returns True if N is of the form X'First .. X'Last where X is the
9834 -- same entity for both attributes.
9836 --------------------
9837 -- First_Last_Ref --
9838 --------------------
9844 begin
9849 then
9850 declare
9853 begin
9857 then
9866 -- Start of processing for Resolve_Range
9868 begin
9871 -- The lower bound should be in Typ. The higher bound can be in Typ's
9872 -- base type if the range is null. It may still be invalid if it is
9873 -- higher than the lower bound. This is checked later in the context in
9874 -- which the range appears.
9879 -- Check for inappropriate range on unordered enumeration type
9883 -- Exclude X'First .. X'Last if X is the same entity for both
9885 and then not First_Last_Ref
9886 then
9888 Error_Msg_NE
9895 -- We have to check the bounds for being within the base range as
9896 -- required for a non-static context. Normally this is automatic and
9897 -- done as part of evaluating expressions, but the N_Range node is an
9898 -- exception, since in GNAT we consider this node to be a subexpression,
9899 -- even though in Ada it is not. The circuit in Sem_Eval could check for
9900 -- this, but that would put the test on the main evaluation path for
9901 -- expressions.
9906 -- Check for an ambiguous range over character literals. This will
9907 -- happen with a membership test involving only literals.
9915 -- If bounds are static, constant-fold them, so size computations are
9916 -- identical between front-end and back-end. Do not perform this
9917 -- transformation while analyzing generic units, as type information
9918 -- would be lost when reanalyzing the constant node in the instance.
9931 --------------------------
9932 -- Resolve_Real_Literal --
9933 --------------------------
9938 begin
9939 -- Special processing for fixed-point literals to make sure that the
9940 -- value is an exact multiple of small where this is required. We skip
9941 -- this for the universal real case, and also for generic types.
9947 then
9948 declare
9955 begin
9956 -- Case of literal is not an exact multiple of the Small
9960 -- For a source program literal for a decimal fixed-point type,
9961 -- this is statically illegal (RM 4.9(36)).
9966 then
9970 -- Generate a warning if literal from source
9973 and then Warn_On_Bad_Fixed_Value
9974 then
9975 Error_Msg_N
9977 N);
9980 -- Replace literal by a value that is the exact representation
9981 -- of a value of the type, i.e. a multiple of the small value,
9982 -- by truncation, since Machine_Rounds is false for all GNAT
9983 -- fixed-point types (RM 4.9(38)).
9993 -- In all cases, set the corresponding integer field
9999 -- Now replace the actual type by the expected type as usual
10005 -----------------------
10006 -- Resolve_Reference --
10007 -----------------------
10012 begin
10013 -- Replace general access with specific type
10021 -- If we are taking the reference of a volatile entity, then treat it as
10022 -- a potential modification of this entity. This is too conservative,
10023 -- but necessary because remove side effects can cause transformations
10024 -- of normal assignments into reference sequences that otherwise fail to
10025 -- notice the modification.
10032 --------------------------------
10033 -- Resolve_Selected_Component --
10034 --------------------------------
10049 -- Check whether this is the initialization of a component within an
10050 -- init proc (by assignment or call to another init proc). If true,
10051 -- there is no need for a discriminant check.
10053 --------------------
10054 -- Init_Component --
10055 --------------------
10058 begin
10059 return Inside_Init_Proc
10065 -- Start of processing for Resolve_Selected_Component
10067 begin
10070 -- Use the context type to select the prefix that has a selector
10071 -- of the correct name and type.
10079 else
10083 -- Locate selected component. For a private prefix the selector
10084 -- can denote a discriminant.
10088 -- The visible components of a class-wide type are those of
10089 -- the root type.
10099 then
10106 else
10110 Error_Msg_N
10115 else
10118 -- There may be an implicit dereference. Retrieve
10119 -- designated record type.
10123 else
10129 -- Resolution chooses the new interpretation.
10130 -- Find the component with the right name.
10135 loop
10152 -- There must be a legal interpretation at this point
10159 else
10160 -- Resolve prefix with its type
10165 -- Generate cross-reference. We needed to wait until full overloading
10166 -- resolution was complete to do this, since otherwise we can't tell if
10167 -- we are an lvalue or not.
10171 else
10175 -- If prefix is an access type, the node will be transformed into an
10176 -- explicit dereference during expansion. The type of the node is the
10177 -- designated type of that of the prefix.
10182 else
10186 -- Set flag for expander if discriminant check required on a component
10187 -- appearing within a variant.
10193 and then
10196 and then not Init_Component
10197 then
10205 -- If the prefix is a record conversion, this may be a renamed
10206 -- discriminant whose bounds differ from those of the original
10207 -- one, so we must ensure that a range check is performed.
10212 then
10216 -- Note: No Eval processing is required, because the prefix is of a
10217 -- record type, or protected type, and neither can possibly be static.
10219 -- If the record type is atomic, and the component is non-atomic, then
10220 -- this is worth a warning, since we have a situation where the access
10221 -- to the component may cause extra read/writes of the atomic array
10222 -- object, or partial word accesses, both of which may be unexpected.
10228 then
10229 Error_Msg_N
10232 Error_Msg_N
10240 -------------------
10241 -- Resolve_Shift --
10242 -------------------
10249 begin
10250 -- We do the resolution using the base type, because intermediate values
10251 -- in expressions always are of the base type, not a subtype of it.
10264 ---------------------------
10265 -- Resolve_Short_Circuit --
10266 ---------------------------
10273 begin
10274 -- Ensure all actions associated with the left operand (e.g.
10275 -- finalization of transient objects) are fully evaluated locally within
10276 -- an expression with actions. This is particularly helpful for coverage
10277 -- analysis. However this should not happen in generics or if option
10278 -- Minimize_Expression_With_Actions is set.
10281 declare
10283 begin
10291 -- Set Comes_From_Source on L to preserve warnings for unset
10292 -- reference.
10301 -- Check for issuing warning for always False assert/check, this happens
10302 -- when assertions are turned off, in which case the pragma Assert/Check
10303 -- was transformed into:
10305 -- if False and then <condition> then ...
10307 -- and we detect this pattern
10309 if Warn_On_Assertion_Failure
10316 then
10317 declare
10320 begin
10321 -- Special handling of Asssert pragma
10325 then
10326 declare
10328 Original_Node
10329 (Expression
10332 begin
10333 -- Don't warn if original condition is explicit False,
10334 -- since obviously the failure is expected in this case.
10338 then
10341 -- Issue warning. We do not want the deletion of the
10342 -- IF/AND-THEN to take this message with it. We achieve this
10343 -- by making sure that the expanded code points to the Sloc
10344 -- of the expression, not the original pragma.
10346 else
10347 -- Note: Use Error_Msg_F here rather than Error_Msg_N.
10348 -- The source location of the expression is not usually
10349 -- the best choice here. For example, it gets located on
10350 -- the last AND keyword in a chain of boolean expressiond
10351 -- AND'ed together. It is best to put the message on the
10352 -- first character of the assertion, which is the effect
10353 -- of the First_Node call here.
10355 Error_Msg_F
10357 Expression
10362 -- Similar processing for Check pragma
10366 then
10367 -- Don't want to warn if original condition is explicit False
10369 declare
10371 Original_Node
10372 (Expression
10374 begin
10377 then
10380 -- Post warning
10382 else
10383 -- Again use Error_Msg_F rather than Error_Msg_N, see
10384 -- comment above for an explanation of why we do this.
10386 Error_Msg_F
10388 Expression
10396 -- Continue with processing of short circuit
10405 -------------------
10406 -- Resolve_Slice --
10407 -------------------
10416 begin
10419 -- Use the context type to select the prefix that yields the correct
10420 -- array type.
10422 declare
10429 begin
10437 then
10445 else
10450 else
10461 else
10471 -- If the prefix is an access to an unconstrained array, we must use
10472 -- the actual subtype of the object to perform the index checks. The
10473 -- object denoted by the prefix is implicit in the node, so we build
10474 -- an explicit representation for it in order to compute the actual
10475 -- subtype.
10480 declare
10484 begin
10495 then
10498 -- If the name is a selected component that depends on discriminants,
10499 -- build an actual subtype for it. This can happen only when the name
10500 -- itself is overloaded; otherwise the actual subtype is created when
10501 -- the selected component is analyzed.
10504 and then Full_Analysis
10506 then
10507 declare
10510 begin
10515 -- Maybe this should just be "else", instead of checking for the
10516 -- specific case of slice??? This is needed for the case where the
10517 -- prefix is an Image attribute, which gets expanded to a slice, and so
10518 -- has a constrained subtype which we want to use for the slice range
10519 -- check applied below (the range check won't get done if the
10520 -- unconstrained subtype of the 'Image is used).
10526 -- Obtain the type of the array index
10530 else
10534 -- If name was overloaded, set slice type correctly now
10538 -- Handle the generation of a range check that compares the array index
10539 -- against the discrete_range. The check is not applied to internally
10540 -- built nodes associated with the expansion of dispatch tables. Check
10541 -- that Ada.Tags has already been loaded to avoid extra dependencies on
10542 -- the unit.
10544 if Tagged_Type_Expansion
10550 then
10553 -- The discrete_range is specified by a subtype indication. Create a
10554 -- shallow copy and inherit the type, parent and source location from
10555 -- the discrete_range. This ensures that the range check is inserted
10556 -- relative to the slice and that the runtime exception points to the
10557 -- proper construct.
10566 -- The discrete_range is a regular range. Resolve the bounds and remove
10567 -- their side effects.
10569 else
10586 -- Check bad use of type with predicates
10588 declare
10591 begin
10594 then
10596 else
10601 Bad_Predicated_Subtype_Use
10606 -- Otherwise here is where we check suspicious indexes
10617 ----------------------------
10618 -- Resolve_String_Literal --
10619 ----------------------------
10630 begin
10631 -- For a string appearing in a concatenation, defer creation of the
10632 -- string_literal_subtype until the end of the resolution of the
10633 -- concatenation, because the literal may be constant-folded away. This
10634 -- is a useful optimization for long concatenation expressions.
10636 -- If the string is an aggregate built for a single character (which
10637 -- happens in a non-static context) or a is null string to which special
10638 -- checks may apply, we build the subtype. Wide strings must also get a
10639 -- string subtype if they come from a one character aggregate. Strings
10640 -- generated by attributes might be static, but it is often hard to
10641 -- determine whether the enclosing context is static, so we generate
10642 -- subtypes for them as well, thus losing some rarer optimizations ???
10643 -- Same for strings that come from a static conversion.
10645 Need_Check :=
10654 -- If the resolving type is itself a string literal subtype, we can just
10655 -- reuse it, since there is no point in creating another.
10661 and then not Need_Check
10663 N_Attribute_Reference,
10664 N_Qualified_Expression,
10665 N_Type_Conversion)
10666 then
10669 -- Do not generate a string literal subtype for the default expression
10670 -- of a formal parameter in GNATprove mode. This is because the string
10671 -- subtype is associated with the freezing actions of the subprogram,
10672 -- however freezing is disabled in GNATprove mode and as a result the
10673 -- subtype is unavailable.
10675 elsif GNATprove_Mode
10677 then
10680 -- Otherwise we must create a string literal subtype. Note that the
10681 -- whole idea of string literal subtypes is simply to avoid the need
10682 -- for building a full fledged array subtype for each literal.
10684 else
10690 or else Need_Check
10691 then
10698 then
10704 -- The validity of a null string has been checked in the call to
10705 -- Eval_String_Literal.
10710 -- Always accept string literal with component type Any_Character, which
10711 -- occurs in error situations and in comparisons of literals, both of
10712 -- which should accept all literals.
10717 -- If the type is bit-packed, then we always transform the string
10718 -- literal into a full fledged aggregate.
10723 -- Deal with cases of Wide_Wide_String, Wide_String, and String
10725 else
10726 -- For Standard.Wide_Wide_String, or any other type whose component
10727 -- type is Standard.Wide_Wide_Character, we know that all the
10728 -- characters in the string must be acceptable, since the parser
10729 -- accepted the characters as valid character literals.
10734 -- For the case of Standard.String, or any other type whose component
10735 -- type is Standard.Character, we must make sure that there are no
10736 -- wide characters in the string, i.e. that it is entirely composed
10737 -- of characters in range of type Character.
10739 -- If the string literal is the result of a static concatenation, the
10740 -- test has already been performed on the components, and need not be
10741 -- repeated.
10745 then
10749 -- If we are out of range, post error. This is one of the
10750 -- very few places that we place the flag in the middle of
10751 -- a token, right under the offending wide character. Not
10752 -- quite clear if this is right wrt wide character encoding
10753 -- sequences, but it's only an error message.
10755 Error_Msg
10762 -- For the case of Standard.Wide_String, or any other type whose
10763 -- component type is Standard.Wide_Character, we must make sure that
10764 -- there are no wide characters in the string, i.e. that it is
10765 -- entirely composed of characters in range of type Wide_Character.
10767 -- If the string literal is the result of a static concatenation,
10768 -- the test has already been performed on the components, and need
10769 -- not be repeated.
10773 then
10777 -- If we are out of range, post error. This is one of the
10778 -- very few places that we place the flag in the middle of
10779 -- a token, right under the offending wide character.
10781 -- This is not quite right, because characters in general
10782 -- will take more than one character position ???
10784 Error_Msg
10791 -- If the root type is not a standard character, then we will convert
10792 -- the string into an aggregate and will let the aggregate code do
10793 -- the checking. Standard Wide_Wide_Character is also OK here.
10795 else
10799 -- See if the component type of the array corresponding to the string
10800 -- has compile time known bounds. If yes we can directly check
10801 -- whether the evaluation of the string will raise constraint error.
10802 -- Otherwise we need to transform the string literal into the
10803 -- corresponding character aggregate and let the aggregate code do
10804 -- the checking.
10808 -- Check for the case of full range, where we are definitely OK
10814 -- Here the range is not the complete base type range, so check
10816 declare
10824 begin
10827 then
10833 then
10834 Apply_Compile_Time_Constraint_Error
10836 CE_Range_Check_Failed,
10847 -- If we got here we meed to transform the string literal into the
10848 -- equivalent qualified positional array aggregate. This is rather
10849 -- heavy artillery for this situation, but it is hard work to avoid.
10851 declare
10856 begin
10857 -- Build the character literals, we give them source locations that
10858 -- correspond to the string positions, which is a bit tricky given
10859 -- the possible presence of wide character escape sequences.
10873 -- Should we have a call to Skip_Wide here ???
10875 -- ??? else
10876 -- Skip_Wide (P);
10884 Expression =>
10891 -------------------------
10892 -- Resolve_Target_Name --
10893 -------------------------
10896 begin
10900 -----------------------------
10901 -- Resolve_Type_Conversion --
10902 -----------------------------
10914 -- Set to False to suppress cases where we want to suppress the test
10915 -- for redundancy to avoid possible false positives on this warning.
10917 begin
10918 if not Conv_OK
10920 then
10924 -- If the Operand Etype is Universal_Fixed, then the conversion is
10925 -- never redundant. We need this check because by the time we have
10926 -- finished the rather complex transformation, the conversion looks
10927 -- redundant when it is not.
10932 -- If the operand is marked as Any_Fixed, then special processing is
10933 -- required. This is also a case where we suppress the test for a
10934 -- redundant conversion, since most certainly it is not redundant.
10939 -- Mixed-mode operation involving a literal. Context must be a fixed
10940 -- type which is applied to the literal subsequently.
10942 -- Multiplication and division involving two fixed type operands must
10943 -- yield a universal real because the result is computed in arbitrary
10944 -- precision.
10950 then
10956 or else
10958 then
10959 -- Return if expression is ambiguous
10964 -- If nothing else, the available fixed type is Duration
10966 else
10970 -- Resolve the real operand with largest available precision
10974 else
10980 -- If the operand is a literal (it could be a non-static and
10981 -- illegal exponentiation) check whether the use of Duration
10982 -- is potentially inaccurate.
10987 then
10988 Error_Msg_N
10991 Error_Msg_N
10998 then
11001 else
11010 -- In SPARK, a type conversion between array types should be restricted
11011 -- to types which have matching static bounds.
11013 -- Protect call to Matching_Static_Array_Bounds to avoid costly
11014 -- operation if not needed.
11021 then
11022 Check_SPARK_05_Restriction
11026 -- In formal mode, the operand of an ancestor type conversion must be an
11027 -- object (not an expression).
11035 then
11041 -- Note: we do the Eval_Type_Conversion call before applying the
11042 -- required checks for a subtype conversion. This is important, since
11043 -- both are prepared under certain circumstances to change the type
11044 -- conversion to a constraint error node, but in the case of
11045 -- Eval_Type_Conversion this may reflect an illegality in the static
11046 -- case, and we would miss the illegality (getting only a warning
11047 -- message), if we applied the type conversion checks first.
11051 -- Even when evaluation is not possible, we may be able to simplify the
11052 -- conversion or its expression. This needs to be done before applying
11053 -- checks, since otherwise the checks may use the original expression
11054 -- and defeat the simplifications. This is specifically the case for
11055 -- elimination of the floating-point Truncation attribute in
11056 -- float-to-int conversions.
11060 -- If after evaluation we still have a type conversion, then we may need
11061 -- to apply checks required for a subtype conversion.
11063 -- Skip these type conversion checks if universal fixed operands
11064 -- operands involved, since range checks are handled separately for
11065 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
11071 then
11075 -- Issue warning for conversion of simple object to its own type. We
11076 -- have to test the original nodes, since they may have been rewritten
11077 -- by various optimizations.
11081 -- Here we test for a redundant conversion if the warning mode is
11082 -- active (and was not locally reset), and we have a type conversion
11083 -- from source not appearing in a generic instance.
11085 if Test_Redundant
11088 and then not In_Instance
11089 then
11093 -- If the node is part of a larger expression, the Target_Type
11094 -- may not be the original type of the node if the context is a
11095 -- condition. Recover original type to see if conversion is needed.
11099 then
11103 -- If we have an entity name, then give the warning if the entity
11104 -- is the right type, or if it is a loop parameter covered by the
11105 -- original type (that's needed because loop parameters have an
11106 -- odd subtype coming from the bounds).
11109 and then
11111 or else
11115 -- If not an entity, then type of expression must match
11118 then
11119 -- One more check, do not give warning if the analyzed conversion
11120 -- has an expression with non-static bounds, and the bounds of the
11121 -- target are static. This avoids junk warnings in cases where the
11122 -- conversion is necessary to establish staticness, for example in
11123 -- a case statement.
11127 then
11130 -- Finally, if this type conversion occurs in a context requiring
11131 -- a prefix, and the expression is a qualified expression then the
11132 -- type conversion is not redundant, since a qualified expression
11133 -- is not a prefix, whereas a type conversion is. For example, "X
11134 -- := T'(Funx(...)).Y;" is illegal because a selected component
11135 -- requires a prefix, but a type conversion makes it legal: "X :=
11136 -- T(T'(Funx(...))).Y;"
11138 -- In Ada 2012, a qualified expression is a name, so this idiom is
11139 -- no longer needed, but we still suppress the warning because it
11140 -- seems unfriendly for warnings to pop up when you switch to the
11141 -- newer language version.
11145 N_Indexed_Component,
11146 N_Selected_Component,
11147 N_Slice,
11148 N_Explicit_Dereference)
11149 then
11152 -- Never warn on conversion to Long_Long_Integer'Base since
11153 -- that is most likely an artifact of the extended overflow
11154 -- checking and comes from complex expanded code.
11159 -- Here we give the redundant conversion warning. If it is an
11160 -- entity, give the name of the entity in the message. If not,
11161 -- just mention the expression.
11163 -- Shoudn't we test Warn_On_Redundant_Constructs here ???
11165 else
11168 Error_Msg_NE -- CODEFIX
11171 else
11172 Error_Msg_NE
11180 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
11181 -- No need to perform any interface conversion if the type of the
11182 -- expression coincides with the target type.
11185 and then Expander_Active
11187 then
11188 declare
11192 begin
11193 -- If the type of the operand is a limited view, use nonlimited
11194 -- view when available. If it is a class-wide type, recover the
11195 -- class-wide type of the nonlimited view.
11199 then
11215 -- Conversion from interface type
11219 -- Ada 2005 (AI-217): Handle entities from limited views
11223 Error_Msg_NE -- CODEFIX
11226 Error_Msg_N
11228 N);
11231 and then not
11234 then
11236 Error_Msg_NE -- CODEFIX
11239 Error_Msg_N
11241 N);
11243 else
11247 -- Conversion to interface type
11251 -- Handle subtypes
11258 or else Interface_Present_In_Ancestor
11261 then
11263 else
11266 Error_Msg_N
11274 -- Ada 2012: once the type conversion is resolved, check whether the
11275 -- operand statisfies the static predicate of the target type.
11281 -- If at this stage we have a real to integer conversion, make sure that
11282 -- the Do_Range_Check flag is set, because such conversions in general
11283 -- need a range check. We only need this if expansion is off.
11284 -- In GNATprove mode, we only do that when converting from fixed-point
11285 -- (as floating-point to integer conversions are now handled in
11286 -- GNATprove mode).
11289 and then not Expander_Active
11294 then
11298 -- Generating C code a type conversion of an access to constrained
11299 -- array type to access to unconstrained array type involves building
11300 -- a fat pointer which in general cannot be generated on the fly. We
11301 -- remove side effects in order to store the result of the conversion
11302 -- into a temporary.
11304 if Modify_Tree_For_C
11311 then
11316 ----------------------
11317 -- Resolve_Unary_Op --
11318 ----------------------
11327 begin
11330 Check_SPARK_05_Restriction
11334 -- Deal with intrinsic unary operators
11340 then
11345 -- Deal with universal cases
11348 or else
11350 then
11357 -- Generate warning for expressions like abs (x mod 2)
11359 if Warn_On_Redundant_Constructs
11361 then
11365 Error_Msg_N -- CODEFIX
11370 -- Deal with reference generation
11377 -- Set overflow checking bit. Much cleverer code needed here eventually
11378 -- and perhaps the Resolve routines should be separated for the various
11379 -- arithmetic operations, since they will need different processing ???
11387 -- Generate warning for expressions like -5 mod 3 for integers. No need
11388 -- to worry in the floating-point case, since parens do not affect the
11389 -- result so there is no point in giving in a warning.
11391 declare
11400 begin
11401 if Warn_On_Questionable_Missing_Parens
11405 then
11408 -- We are looking for cases where the right operand is not
11409 -- parenthesized, and is a binary operator, multiply, divide, or
11410 -- mod. These are the cases where the grouping can affect results.
11414 then
11415 -- For mod, we always give the warning, since the value is
11416 -- affected by the parenthesization (e.g. (-5) mod 315 /=
11417 -- -(5 mod 315)). But for the other cases, the only concern is
11418 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
11419 -- overflows, but (-2) * 64 does not). So we try to give the
11420 -- message only when overflow is possible.
11424 then
11429 else
11435 else
11439 -- Note that the test below is deliberately excluding the
11440 -- largest negative number, since that is a potentially
11441 -- troublesome case (e.g. -2 * x, where the result is the
11442 -- largest negative integer has an overflow with 2 * x).
11449 -- For the multiplication case, the only case we have to worry
11450 -- about is when (-a)*b is exactly the largest negative number
11451 -- so that -(a*b) can cause overflow. This can only happen if
11452 -- a is a power of 2, and more generally if any operand is a
11453 -- constant that is not a power of 2, then the parentheses
11454 -- cannot affect whether overflow occurs. We only bother to
11455 -- test the left most operand
11457 -- Loop looking at left operands for one that has known value
11464 -- Operand value of 0 or 1 skips warning
11469 -- Otherwise check power of 2, if power of 2, warn, if
11470 -- anything else, skip warning.
11472 else
11476 else
11485 -- Keep looking at left operands
11490 -- For rem or "/" we can only have a problematic situation
11491 -- if the divisor has a value of minus one or one. Otherwise
11492 -- overflow is impossible (divisor > 1) or we have a case of
11493 -- division by zero in any case.
11498 then
11502 -- If we fall through warning should be issued
11504 -- Shouldn't we test Warn_On_Questionable_Missing_Parens ???
11506 Error_Msg_N
11513 ----------------------------------
11514 -- Resolve_Unchecked_Expression --
11515 ----------------------------------
11517 procedure Resolve_Unchecked_Expression
11520 is
11521 begin
11526 ---------------------------------------
11527 -- Resolve_Unchecked_Type_Conversion --
11528 ---------------------------------------
11530 procedure Resolve_Unchecked_Type_Conversion
11533 is
11539 begin
11540 -- Resolve operand using its own type
11544 -- In an inlined context, the unchecked conversion may be applied
11545 -- to a literal, in which case its type is the type of the context.
11546 -- (In other contexts conversions cannot apply to literals).
11548 if In_Inlined_Body
11552 then
11560 ------------------------------
11561 -- Rewrite_Operator_As_Call --
11562 ------------------------------
11569 begin
11576 New_N :=
11587 ------------------------------
11588 -- Rewrite_Renamed_Operator --
11589 ------------------------------
11591 procedure Rewrite_Renamed_Operator
11595 is
11600 begin
11601 -- Do not perform this transformation within a pre/postcondition,
11602 -- because the expression will be reanalyzed, and the transformation
11603 -- might affect the visibility of the operator, e.g. in an instance.
11604 -- Note that fully analyzed and expanded pre/postconditions appear as
11605 -- pragma Check equivalents.
11611 -- Likewise when an expression function is being preanalyzed, since the
11612 -- expression will be reanalyzed as part of the generated body.
11615 declare
11617 begin
11620 N_Expression_Function
11621 then
11627 -- Rewrite the operator node using the real operator, not its renaming.
11628 -- Exclude user-defined intrinsic operations of the same name, which are
11629 -- treated separately and rewritten as calls.
11638 -- Indicate that both the original entity and its renaming are
11639 -- referenced at this point.
11650 -- If the context type is private, add the appropriate conversions so
11651 -- that the operator is applied to the full view. This is done in the
11652 -- routines that resolve intrinsic operators.
11656 when N_Op_Add
11657 | N_Op_Divide
11658 | N_Op_Expon
11659 | N_Op_Mod
11660 | N_Op_Multiply
11661 | N_Op_Rem
11662 | N_Op_Subtract
11663 =>
11666 when N_Op_Abs
11667 | N_Op_Minus
11668 | N_Op_Plus
11669 =>
11679 -- Operator renames a user-defined operator of the same name. Use the
11680 -- original operator in the node, which is the one Gigi knows about.
11687 -----------------------
11688 -- Set_Slice_Subtype --
11689 -----------------------
11691 -- Build an implicit subtype declaration to represent the type delivered by
11692 -- the slice. This is an abbreviated version of an array subtype. We define
11693 -- an index subtype for the slice, using either the subtype name or the
11694 -- discrete range of the slice. To be consistent with index usage elsewhere
11695 -- we create a list header to hold the single index. This list is not
11696 -- otherwise attached to the syntax tree.
11707 begin
11713 else
11714 -- We force the evaluation of a range. This is definitely needed in
11715 -- the renamed case, and seems safer to do unconditionally. Note in
11716 -- any case that since we will create and insert an Itype referring
11717 -- to this range, we must make sure any side effect removal actions
11718 -- are inserted before the Itype definition.
11724 -- If the discrete range is given by a subtype indication, the
11725 -- type of the slice is the base of the subtype mark.
11728 declare
11730 begin
11739 -- Take a new copy of Drange (where bounds have been rewritten to
11740 -- reference side-effect-free names). Using a separate tree ensures
11741 -- that further expansion (e.g. while rewriting a slice assignment
11742 -- into a FOR loop) does not attempt to remove side effects on the
11743 -- bounds again (which would cause the bounds in the index subtype
11744 -- definition to refer to temporaries before they are defined) (the
11745 -- reason is that some names are considered side effect free here
11746 -- for the subtype, but not in the context of a loop iteration
11747 -- scheme).
11768 -- The Etype of the existing Slice node is reset to this slice subtype.
11769 -- Its bounds are obtained from its first index.
11773 -- For bit-packed slice subtypes, freeze immediately (except in the case
11774 -- of being in a "spec expression" where we never freeze when we first
11775 -- see the expression).
11780 -- For all other cases insert an itype reference in the slice's actions
11781 -- so that the itype is frozen at the proper place in the tree (i.e. at
11782 -- the point where actions for the slice are analyzed). Note that this
11783 -- is different from freezing the itype immediately, which might be
11784 -- premature (e.g. if the slice is within a transient scope). This needs
11785 -- to be done only if expansion is enabled.
11792 --------------------------------
11793 -- Set_String_Literal_Subtype --
11794 --------------------------------
11802 begin
11814 -- The low bound is set from the low bound of the corresponding index
11815 -- type. Note that we do not store the high bound in the string literal
11816 -- subtype, but it can be deduced if necessary from the length and the
11817 -- low bound.
11822 -- If the lower bound is not static we create a range for the string
11823 -- literal, using the index type and the known length of the literal.
11824 -- The index type is not necessarily Positive, so the upper bound is
11825 -- computed as T'Val (T'Pos (Low_Bound) + L - 1).
11827 else
11828 declare
11834 Prefix =>
11838 Left_Opnd =>
11841 Prefix =>
11843 Expressions =>
11845 Right_Opnd =>
11854 begin
11856 Set_String_Literal_Low_Bound
11859 else
11860 -- If the index type is an enumeration type, build bounds
11861 -- expression with attributes.
11863 Set_String_Literal_Low_Bound
11867 Prefix =>
11874 -- Build bona fide subtype for the string, and wrap it in an
11875 -- unchecked conversion, because the backend expects the
11876 -- String_Literal_Subtype to have a static lower bound.
11878 Index_Subtype :=
11885 -- In the context, the Index_Type may already have a constraint,
11886 -- so use common base type on string subtype. The base type may
11887 -- be used when generating attributes of the string, for example
11888 -- in the context of a slice assignment.
11913 ------------------------------
11914 -- Simplify_Type_Conversion --
11915 ------------------------------
11918 begin
11920 declare
11925 begin
11926 -- Special processing if the conversion is the expression of a
11927 -- Rounding or Truncation attribute reference. In this case we
11928 -- replace:
11930 -- ityp (ftyp'Rounding (x)) or ityp (ftyp'Truncation (x))
11932 -- by
11934 -- ityp (x)
11936 -- with the Float_Truncate flag set to False or True respectively,
11937 -- which is more efficient.
11940 and then
11946 Name_Truncation)
11947 then
11948 declare
11951 begin
11961 -----------------------------
11962 -- Unique_Fixed_Point_Type --
11963 -----------------------------
11967 -- Give error messages for true ambiguity. Messages are posted on node
11968 -- N, and entities T1, T2 are the possible interpretations.
11970 -----------------------
11971 -- Fixed_Point_Error --
11972 -----------------------
11975 begin
11981 -- Local variables
11989 -- Start of processing for Unique_Fixed_Point_Type
11991 begin
11992 -- The operations on Duration are visible, so Duration is always a
11993 -- possible interpretation.
11997 -- Look for fixed-point types in enclosing scopes
12006 then
12010 else
12021 -- Look for visible fixed type declarations in the context
12032 then
12036 else
12051 else
12052 -- When the context is a type conversion, issue the warning on the
12053 -- expression of the conversion because it is the actual operation.
12057 else
12061 Error_Msg_NE
12068 ----------------------
12069 -- Valid_Conversion --
12070 ----------------------
12072 function Valid_Conversion
12077 is
12082 function Conversion_Check
12085 -- Little routine to post Msg if Valid is False, returns Valid value
12088 -- If Report_Errs, then calls Errout.Error_Msg_N with its arguments
12090 procedure Conversion_Error_NE
12094 -- If Report_Errs, then calls Errout.Error_Msg_NE with its arguments
12097 -- Return True if expression is within an instance but is not in one of
12098 -- the actuals of the instantiation. Type conversions within an instance
12099 -- are not rechecked because type visbility may lead to spurious errors,
12100 -- but conversions in an actual for a formal object must be checked.
12102 function Valid_Tagged_Conversion
12105 -- Specifically test for validity of tagged conversions
12108 -- Check index and component conformance, and accessibility levels if
12109 -- the component types are anonymous access types (Ada 2005).
12111 ----------------------
12112 -- Conversion_Check --
12113 ----------------------
12115 function Conversion_Check
12118 is
12119 begin
12120 if not Valid
12122 -- A generic unit has already been analyzed and we have verified
12123 -- that a particular conversion is OK in that context. Since the
12124 -- instance is reanalyzed without relying on the relationships
12125 -- established during the analysis of the generic, it is possible
12126 -- to end up with inconsistent views of private types. Do not emit
12127 -- the error message in such cases. The rest of the machinery in
12128 -- Valid_Conversion still ensures the proper compatibility of
12129 -- target and operand types.
12131 and then not In_Instance_Code
12132 then
12139 ------------------------
12140 -- Conversion_Error_N --
12141 ------------------------
12144 begin
12150 -------------------------
12151 -- Conversion_Error_NE --
12152 -------------------------
12154 procedure Conversion_Error_NE
12158 is
12159 begin
12165 ----------------------
12166 -- In_Instance_Code --
12167 ----------------------
12172 begin
12176 else
12180 -- The expression is part of an actual object if it appears in
12181 -- the generated object declaration in the instance.
12185 then
12188 else
12189 exit when
12198 -- Otherwise the expression appears within the instantiated unit
12204 ----------------------------
12205 -- Valid_Array_Conversion --
12206 ----------------------------
12223 begin
12224 -- Error if wrong number of dimensions
12226 if
12228 then
12229 Conversion_Error_N
12233 -- Number of dimensions matches
12235 else
12236 -- Loop through indexes of the two arrays
12244 -- Error if index types are incompatible
12250 then
12251 Conversion_Error_N
12253 Operand);
12261 -- If component types have same base type, all set
12266 -- Here if base types of components are not the same. The only
12267 -- time this is allowed is if we have anonymous access types.
12269 -- The conversion of arrays of anonymous access types can lead
12270 -- to dangling pointers. AI-392 formalizes the accessibility
12271 -- checks that must be applied to such conversions to prevent
12272 -- out-of-scope references.
12274 elsif Ekind_In
12276 E_Anonymous_Access_Subprogram_Type)
12278 and then
12280 then
12283 then
12286 Conversion_Error_N
12296 -- Conversion not allowed because of accessibility levels
12298 else
12299 Conversion_Error_N
12305 else
12309 -- All other cases where component base types do not match
12311 else
12312 Conversion_Error_N
12314 Operand);
12318 -- Check that component subtypes statically match. For numeric
12319 -- types this means that both must be either constrained or
12320 -- unconstrained. For enumeration types the bounds must match.
12321 -- All of this is checked in Subtypes_Statically_Match.
12323 if not Subtypes_Statically_Match
12325 then
12326 Conversion_Error_N
12335 -----------------------------
12336 -- Valid_Tagged_Conversion --
12337 -----------------------------
12339 function Valid_Tagged_Conversion
12342 is
12343 begin
12344 -- Upward conversions are allowed (RM 4.6(22))
12348 then
12351 -- Downward conversion are allowed if the operand is class-wide
12352 -- (RM 4.6(23)).
12356 then
12361 then
12362 return
12366 -- Ada 2005 (AI-251): The conversion to/from interface types is
12367 -- always valid. The types involved may be class-wide (sub)types.
12371 then
12374 -- If the operand is a class-wide type obtained through a limited_
12375 -- with clause, and the context includes the nonlimited view, use
12376 -- it to determine whether the conversion is legal.
12382 then
12387 then
12390 else
12391 Conversion_Error_NE
12398 -- Start of processing for Valid_Conversion
12400 begin
12404 declare
12412 begin
12413 -- Remove procedure calls, which syntactically cannot appear in
12414 -- this context, but which cannot be removed by type checking,
12415 -- because the context does not impose a type.
12417 -- The node may be labelled overloaded, but still contain only one
12418 -- interpretation because others were discarded earlier. If this
12419 -- is the case, retain the single interpretation if legal.
12427 then
12428 -- More than one candidate interpretation is available
12436 -- When compiling for a system where Address is of a visible
12437 -- integer type, spurious ambiguities can be produced when
12438 -- arithmetic operations have a literal operand and return
12439 -- System.Address or a descendant of it. These ambiguities
12440 -- are usually resolved by the context, but for conversions
12441 -- there is no context type and the removal of the spurious
12442 -- operations must be done explicitly here.
12444 if not Address_Is_Private
12446 then
12471 Conversion_Error_N
12474 -- If the interpretation involves a standard operator, use
12475 -- the location of the type, which may be user-defined.
12479 else
12483 Conversion_Error_N -- CODEFIX
12488 else
12492 Conversion_Error_N -- CODEFIX
12504 -- Deal with conversion of integer type to address if the pragma
12505 -- Allow_Integer_Address is in effect. We convert the conversion to
12506 -- an unchecked conversion in this case and we are all done.
12514 -- If we are within a child unit, check whether the type of the
12515 -- expression has an ancestor in a parent unit, in which case it
12516 -- belongs to its derivation class even if the ancestor is private.
12517 -- See RM 7.3.1 (5.2/3).
12521 -- Numeric types
12525 -- A universal fixed expression can be converted to any numeric type
12530 -- Also no need to check when in an instance or inlined body, because
12531 -- the legality has been established when the template was analyzed.
12532 -- Furthermore, numeric conversions may occur where only a private
12533 -- view of the operand type is visible at the instantiation point.
12534 -- This results in a spurious error if we check that the operand type
12535 -- is a numeric type.
12537 -- Note: in a previous version of this unit, the following tests were
12538 -- applied only for generated code (Comes_From_Source set to False),
12539 -- but in fact the test is required for source code as well, since
12540 -- this situation can arise in source code.
12545 -- Otherwise we need the conversion check
12547 else
12548 return Conversion_Check
12550 or else
12556 -- Array types
12562 then
12563 Conversion_Error_N
12567 else
12571 -- Ada 2005 (AI-251): Internally generated conversions of access to
12572 -- interface types added to force the displacement of the pointer to
12573 -- reference the corresponding dispatch table.
12578 then
12581 -- Ada 2005 (AI-251): Anonymous access types where target references an
12582 -- interface type.
12586 E_Anonymous_Access_Type)
12588 then
12589 -- Check the static accessibility rule of 4.6(17). Note that the
12590 -- check is not enforced when within an instance body, since the
12591 -- RM requires such cases to be caught at run time.
12593 -- If the operand is a rewriting of an allocator no check is needed
12594 -- because there are no accessibility issues.
12602 then
12603 -- In an instance, this is a run-time check, but one we know
12604 -- will fail, so generate an appropriate warning. The raise
12605 -- will be generated by Expand_N_Type_Conversion.
12609 Conversion_Error_N
12611 Operand);
12614 else
12615 Conversion_Error_N
12617 Operand);
12621 -- Special accessibility checks are needed in the case of access
12622 -- discriminants declared for a limited type.
12626 then
12627 -- When the operand is a selected access discriminant the check
12628 -- needs to be made against the level of the object denoted by
12629 -- the prefix of the selected name (Object_Access_Level handles
12630 -- checking the prefix of the operand for this case).
12635 then
12636 -- In an instance, this is a run-time check, but one we know
12637 -- will fail, so generate an appropriate warning. The raise
12638 -- will be generated by Expand_N_Type_Conversion.
12642 Conversion_Error_N
12647 -- Real error if not in instance body
12649 else
12650 Conversion_Error_N
12657 -- The case of a reference to an access discriminant from
12658 -- within a limited type declaration (which will appear as
12659 -- a discriminal) is always illegal because the level of the
12660 -- discriminant is considered to be deeper than any (nameable)
12661 -- access type.
12665 and then
12668 then
12669 Conversion_Error_N
12671 Operand);
12679 -- General and anonymous access types
12682 E_Anonymous_Access_Type)
12683 and then
12684 Conversion_Check
12686 and then not
12688 E_Access_Protected_Subprogram_Type),
12690 then
12693 then
12694 Conversion_Error_N
12699 -- Check the static accessibility rule of 4.6(17). Note that the
12700 -- check is not enforced when within an instance body, since the RM
12701 -- requires such cases to be caught at run time.
12706 N_Object_Declaration
12707 then
12708 -- Ada 2012 (AI05-0149): Perform legality checking on implicit
12709 -- conversions from an anonymous access type to a named general
12710 -- access type. Such conversions are not allowed in the case of
12711 -- access parameters and stand-alone objects of an anonymous
12712 -- access type. The implicit conversion case is recognized by
12713 -- testing that Comes_From_Source is False and that it's been
12714 -- rewritten. The Comes_From_Source test isn't sufficient because
12715 -- nodes in inlined calls to predefined library routines can have
12716 -- Comes_From_Source set to False. (Is there a better way to test
12717 -- for implicit conversions???)
12724 then
12727 -- Implicit conversions aren't allowed for objects of an
12728 -- anonymous access type, since such objects have nonstatic
12729 -- levels in Ada 2012.
12732 N_Object_Declaration
12733 then
12734 Conversion_Error_N
12739 -- Implicit conversions aren't allowed for anonymous access
12740 -- parameters. The "not Is_Local_Anonymous_Access_Type" test
12741 -- is done to exclude anonymous access results.
12745 N_Function_Specification,
12746 N_Procedure_Specification)
12747 then
12748 Conversion_Error_N
12753 -- This is a case where there's an enclosing object whose
12754 -- to which the "statically deeper than" relationship does
12755 -- not apply (such as an access discriminant selected from
12756 -- a dereference of an access parameter).
12760 then
12761 Conversion_Error_N
12766 -- In other cases, the level of the operand's type must be
12767 -- statically less deep than that of the target type, else
12768 -- implicit conversion is disallowed (by RM12-8.6(27.1/3)).
12772 then
12773 Conversion_Error_N
12782 then
12783 -- In an instance, this is a run-time check, but one we know
12784 -- will fail, so generate an appropriate warning. The raise
12785 -- will be generated by Expand_N_Type_Conversion.
12789 Conversion_Error_N
12791 Operand);
12794 -- If not in an instance body, this is a real error
12796 else
12797 -- Avoid generation of spurious error message
12800 Conversion_Error_N
12802 Operand);
12808 -- Special accessibility checks are needed in the case of access
12809 -- discriminants declared for a limited type.
12813 then
12814 -- When the operand is a selected access discriminant the check
12815 -- needs to be made against the level of the object denoted by
12816 -- the prefix of the selected name (Object_Access_Level handles
12817 -- checking the prefix of the operand for this case).
12822 then
12823 -- In an instance, this is a run-time check, but one we know
12824 -- will fail, so generate an appropriate warning. The raise
12825 -- will be generated by Expand_N_Type_Conversion.
12829 Conversion_Error_N
12834 -- If not in an instance body, this is a real error
12836 else
12837 Conversion_Error_N
12844 -- The case of a reference to an access discriminant from
12845 -- within a limited type declaration (which will appear as
12846 -- a discriminal) is always illegal because the level of the
12847 -- discriminant is considered to be deeper than any (nameable)
12848 -- access type.
12851 and then
12854 then
12855 Conversion_Error_N
12857 Operand);
12863 -- In the presence of limited_with clauses we have to use nonlimited
12864 -- views, if available.
12868 -- Helper function to handle limited views
12870 --------------------------
12871 -- Full_Designated_Type --
12872 --------------------------
12877 begin
12878 -- Handle the limited view of a type
12882 then
12884 else
12889 -- Local Declarations
12897 -- Start of processing for Check_Limited
12899 begin
12903 else
12905 Conversion_Error_NE
12910 -- Ada 2005 AI-384: legality rule is symmetric in both
12911 -- designated types. The conversion is legal (with possible
12912 -- constraint check) if either designated type is
12913 -- unconstrained.
12916 or else
12918 and then
12921 then
12922 -- Special case, if Value_Size has been used to make the
12923 -- sizes different, the conversion is not allowed even
12924 -- though the subtypes statically match.
12929 then
12930 Conversion_Error_NE
12933 Conversion_Error_NE
12938 -- Normal case where conversion is allowed
12940 else
12944 else
12945 Error_Msg_NE
12953 -- Access to subprogram types. If the operand is an access parameter,
12954 -- the type has a deeper accessibility that any master, and cannot be
12955 -- assigned. We must make an exception if the conversion is part of an
12956 -- assignment and the target is the return object of an extended return
12957 -- statement, because in that case the accessibility check takes place
12958 -- after the return.
12962 -- Note: this test of Opnd_Type is there to prevent entering this
12963 -- branch in the case of a remote access to subprogram type, which
12964 -- is internally represented as an E_Record_Type.
12967 then
12971 and then
12975 then
12976 Conversion_Error_N
12978 Operand);
12979 Conversion_Error_N
12982 Operand);
12984 Error_Msg_NE
12989 -- Check that the designated types are subtype conformant
12995 -- Check the static accessibility rule of 4.6(20)
12999 then
13000 Conversion_Error_N
13002 Operand);
13004 -- Check that if the operand type is declared in a generic body,
13005 -- then the target type must be declared within that same body
13006 -- (enforces last sentence of 4.6(20)).
13009 declare
13015 begin
13022 Conversion_Error_N
13031 -- Remote access to subprogram types
13035 then
13036 -- It is valid to convert from one RAS type to another provided
13037 -- that their specification statically match.
13039 -- Note: at this point, remote access to subprogram types have been
13040 -- expanded to their E_Record_Type representation, and we need to
13041 -- go back to the original access type definition using the
13042 -- Corresponding_Remote_Type attribute in order to check that the
13043 -- designated profiles match.
13048 Check_Subtype_Conformant
13051 Old_Id =>
13053 Err_Loc =>
13054 N);
13057 -- If it was legal in the generic, it's legal in the instance
13062 -- If both are tagged types, check legality of view conversions
13065 and then
13067 then
13070 -- Types derived from the same root type are convertible
13075 -- In an instance or an inlined body, there may be inconsistent views of
13076 -- the same type, or of types derived from a common root.
13079 and then
13082 then
13085 -- Special check for common access type error case
13089 then
13091 Conversion_Error_NE -- CODEFIX
13095 -- Here we have a real conversion error
13097 else
13098 Conversion_Error_NE