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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) 1992-2007, 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 ------------------------------------------------------------------------------
78 -----------------------
79 -- Local Subprograms --
80 -----------------------
82 -- Second pass (top-down) type checking and overload resolution procedures
83 -- Typ is the type required by context. These procedures propagate the
84 -- type information recursively to the descendants of N. If the node
85 -- is not overloaded, its Etype is established in the first pass. If
86 -- overloaded, the Resolve routines set the correct type. For arith.
87 -- operators, the Etype is the base type of the context.
89 -- Note that Resolve_Attribute is separated off in Sem_Attr
92 -- Enforce the restrictions on the use of discriminants when constraining
93 -- a component of a discriminated type (record or concurrent type).
96 -- Given a node for an operator associated with type T, check that
97 -- the operator is visible. Operators all of whose operands are
98 -- universal must be checked for visibility during resolution
99 -- because their type is not determinable based on their operands.
101 procedure Check_Fully_Declared_Prefix
104 -- Check that the type of the prefix of a dereference is not incomplete
107 -- Given a call node, N, which is known to occur immediately within the
108 -- subprogram being called, determines whether it is a detectable case of
109 -- an infinite recursion, and if so, outputs appropriate messages. Returns
110 -- True if an infinite recursion is detected, and False otherwise.
113 -- If the type of the object being initialized uses the secondary stack
114 -- directly or indirectly, create a transient scope for the call to the
115 -- init proc. This is because we do not create transient scopes for the
116 -- initialization of individual components within the init proc itself.
117 -- Could be optimized away perhaps?
120 -- Determine whether E is an access type declared by an access
121 -- declaration, and not an (anonymous) allocator type.
124 -- Utility to check whether the name in the call is a predefined
125 -- operator, in which case the call is made into an operator node.
126 -- An instance of an intrinsic conversion operation may be given
127 -- an operator name, but is not treated like an operator.
130 -- If a default expression in entry call N depends on the discriminants
131 -- of the task, it must be replaced with a reference to the discriminant
132 -- of the task being called.
134 procedure Resolve_Op_Concat_Arg
139 -- Internal procedure for Resolve_Op_Concat to resolve one operand of
140 -- concatenation operator. The operand is either of the array type or of
141 -- the component type. If the operand is an aggregate, and the component
142 -- type is composite, this is ambiguous if component type has aggregates.
145 -- Does the first part of the work of Resolve_Op_Concat
148 -- Does the "rest" of the work of Resolve_Op_Concat, after the left operand
149 -- has been resolved. See Resolve_Op_Concat for details.
184 function Operator_Kind
187 -- Utility to map the name of an operator into the corresponding Node. Used
188 -- by other node rewriting procedures.
191 -- Resolve actuals of call, and add default expressions for missing ones.
192 -- N is the Node_Id for the subprogram call, and Nam is the entity of the
193 -- called subprogram.
196 -- Called from Resolve_Call, when the prefix denotes an entry or element
197 -- of entry family. Actuals are resolved as for subprograms, and the node
198 -- is rebuilt as an entry call. Also called for protected operations. Typ
199 -- is the context type, which is used when the operation is a protected
200 -- function with no arguments, and the return value is indexed.
203 -- A call to a user-defined intrinsic operator is rewritten as a call
204 -- to the corresponding predefined operator, with suitable conversions.
207 -- Ditto, for unary operators (only arithmetic ones)
210 -- If an operator node resolves to a call to a user-defined operator,
211 -- rewrite the node as a function call.
213 procedure Make_Call_Into_Operator
217 -- Inverse transformation: if an operator is given in functional notation,
218 -- then after resolving the node, transform into an operator node, so
219 -- that operands are resolved properly. Recall that predefined operators
220 -- do not have a full signature and special resolution rules apply.
222 procedure Rewrite_Renamed_Operator
226 -- An operator can rename another, e.g. in an instantiation. In that
227 -- case, the proper operator node must be constructed and resolved.
230 -- The String_Literal_Subtype is built for all strings that are not
231 -- operands of a static concatenation operation. If the argument is
232 -- not a N_String_Literal node, then the call has no effect.
235 -- Build subtype of array type, with the range specified by the slice
238 -- Called after N has been resolved and evaluated, but before range checks
239 -- have been applied. Currently simplifies a combination of floating-point
240 -- to integer conversion and Truncation attribute.
243 -- A universal_fixed expression in an universal context is unambiguous
244 -- if there is only one applicable fixed point type. Determining whether
245 -- there is only one requires a search over all visible entities, and
246 -- happens only in very pathological cases (see 6115-006).
248 function Valid_Conversion
252 -- Verify legality rules given in 4.6 (8-23). Target is the target
253 -- type of the conversion, which may be an implicit conversion of
254 -- an actual parameter to an anonymous access type (in which case
255 -- N denotes the actual parameter and N = Operand).
257 -------------------------
258 -- Ambiguous_Character --
259 -------------------------
264 begin
268 -- First the ones in Standard
270 Error_Msg_N
272 Error_Msg_N
275 -- Include Wide_Wide_Character in Ada 2005 mode
278 Error_Msg_N
282 -- Now any other types that match
292 -------------------------
293 -- Analyze_And_Resolve --
294 -------------------------
297 begin
303 begin
308 -- Version withs check(s) suppressed
310 procedure Analyze_And_Resolve
314 is
317 begin
319 declare
321 begin
327 else
328 declare
331 begin
339 and then Scope_Is_Transient
340 then
341 -- This can only happen if a transient scope was created
342 -- for an inner expression, which will be removed upon
343 -- completion of the analysis of an enclosing construct.
344 -- The transient scope must have the suppress status of
345 -- the enclosing environment, not of this Analyze call.
348 Scope_Suppress;
352 procedure Analyze_And_Resolve
355 is
358 begin
360 declare
362 begin
368 else
369 declare
372 begin
380 and then Scope_Is_Transient
381 then
383 Scope_Suppress;
387 ----------------------------
388 -- Check_Discriminant_Use --
389 ----------------------------
397 begin
398 -- Any use in a default expression is legal
405 -- Discriminant cannot be used to constrain a scalar type
412 then
417 -- The following check catches the unusual case where
418 -- a discriminant appears within an index constraint
419 -- that is part of a larger expression within a constraint
420 -- on a component, e.g. "C : Int range 1 .. F (new A(1 .. D))".
421 -- For now we only check case of record components, and
422 -- note that a similar check should also apply in the
423 -- case of discriminant constraints below. ???
425 -- Note that the check for N_Subtype_Declaration below is to
426 -- detect the valid use of discriminants in the constraints of a
427 -- subtype declaration when this subtype declaration appears
428 -- inside the scope of a record type (which is syntactically
429 -- illegal, but which may be created as part of derived type
430 -- processing for records). See Sem_Ch3.Build_Derived_Record_Type
431 -- for more info.
435 and then not
437 and then
439 or else
442 then
443 Error_Msg_N
448 -- Detect a common beginner error:
450 -- type R (D : Positive := 100) is record
451 -- Name : String (1 .. D);
452 -- end record;
454 -- The default value causes an object of type R to be
455 -- allocated with room for Positive'Last characters.
457 declare
464 -- Return True if type T has a large enough range that
465 -- any array whose index type covered the whole range of
466 -- the type would likely raise Storage_Error.
468 ------------------------
469 -- Large_Storage_Type --
470 ------------------------
473 begin
474 return
475 T = Standard_Integer
476 or else
477 T = Standard_Positive
478 or else
482 begin
483 -- Check that the Disc has a large range
489 -- If the enclosing type is limited, we allocate only the
490 -- default value, not the maximum, and there is no need for
491 -- a warning.
497 -- Check that it is the high bound
501 then
505 -- Check the array allows a large range at this bound.
506 -- First find the array
520 -- Next, find the dimension
528 loop
537 -- Now, check the dimension has a large range
543 -- Warn about the danger
545 Error_Msg_N
555 -- Legal case is in index or discriminant constraint
559 then
561 Error_Msg_N
566 then
567 Error_Msg_N
573 -- Otherwise, context is an expression. It should not be within
574 -- (i.e. a subexpression of) a constraint for a component.
576 else
582 loop
588 -- If the discriminant is used in an expression that is a bound
589 -- of a scalar type, an Itype is created and the bounds are attached
590 -- to its range, not to the original subtype indication. Such use
591 -- is of course a double fault.
594 and then
596 or else
600 -- The constraint itself may be given by a subtype indication,
601 -- rather than by a more common discrete range.
604 and then
608 then
609 Error_Msg_N
615 --------------------------------
616 -- Check_For_Visible_Operator --
617 --------------------------------
620 begin
622 Error_Msg_NE
628 ----------------------------------
629 -- Check_Fully_Declared_Prefix --
630 ----------------------------------
632 procedure Check_Fully_Declared_Prefix
635 is
636 begin
637 -- Check that the designated type of the prefix of a dereference is
638 -- not an incomplete type. This cannot be done unconditionally, because
639 -- dereferences of private types are legal in default expressions. This
640 -- case is taken care of in Check_Fully_Declared, called below. There
641 -- are also 2005 cases where it is legal for the prefix to be unfrozen.
643 -- This consideration also applies to similar checks for allocators,
644 -- qualified expressions, and type conversions.
646 -- An additional exception concerns other per-object expressions that
647 -- are not directly related to component declarations, in particular
648 -- representation pragmas for tasks. These will be per-object
649 -- expressions if they depend on discriminants or some global entity.
650 -- If the task has access discriminants, the designated type may be
651 -- incomplete at the point the expression is resolved. This resolution
652 -- takes place within the body of the initialization procedure, where
653 -- the discriminant is replaced by its discriminal.
657 then
660 -- Ada 2005 (AI-326): Tagged incomplete types allowed. The wrong usages
661 -- are handled by Analyze_Access_Attribute, Analyze_Assignment,
662 -- Analyze_Object_Renaming, and Freeze_Entity.
667 E_Incomplete_Type
669 then
671 else
676 ------------------------------
677 -- Check_Infinite_Recursion --
678 ------------------------------
685 -- Check whether list of actuals is identical to list of formals
686 -- of called function (which is also the enclosing scope).
688 ------------------------
689 -- Same_Argument_List --
690 ------------------------
697 begin
700 else
709 then
720 -- Start of processing for Check_Infinite_Recursion
722 begin
723 -- Loop moving up tree, quitting if something tells us we are
724 -- definitely not in an infinite recursion situation.
727 loop
735 then
740 then
741 -- If the call is the expression of a return statement and
742 -- the actuals are identical to the formals, it's worth a
743 -- warning. However, we skip this if there is an immediately
744 -- preceding raise statement, since the call is never executed.
746 -- Furthermore, this corresponds to a common idiom:
748 -- function F (L : Thing) return Boolean is
749 -- begin
750 -- raise Program_Error;
751 -- return F (L);
752 -- end F;
754 -- for generating a stub function
757 and then Same_Argument_List
758 then
761 -- OK, return statement is in a statement list, look for raise
763 declare
766 begin
767 -- Skip past N_Freeze_Entity nodes generated by expansion
772 loop
776 -- If no raise statement, give warning
779 and then
787 else
798 -------------------------------
799 -- Check_Initialization_Call --
800 -------------------------------
806 -- Check whether the creation of an object of the type will involve
807 -- use of the secondary stack. If T is a record type, this is true
808 -- if the expression for some component uses the secondary stack, eg.
809 -- through a call to a function that returns an unconstrained value.
810 -- False if T is controlled, because cleanups occur elsewhere.
812 -------------
813 -- Uses_SS --
814 -------------
821 begin
822 -- Normally we want to use the underlying type, but if it's not set
823 -- then continue with T.
840 then
841 -- The expression for a dynamic component may be rewritten
842 -- as a dereference, so retrieve original node.
846 -- Return True if the expression is a call to a function
847 -- (including an attribute function such as Image) with
848 -- a result that requires a transient scope.
854 then
867 else
872 -- Start of processing for Check_Initialization_Call
874 begin
875 -- Establish a transient scope if the type needs it
882 ------------------------------
883 -- Check_Parameterless_Call --
884 ------------------------------
890 -- If the prefix is of an access_to_subprogram type, the node must be
891 -- rewritten as a call. Ditto if the prefix is overloaded and all its
892 -- interpretations are access to subprograms.
894 ---------------------------
895 -- Prefix_Is_Access_Subp --
896 ---------------------------
902 begin
904 return
907 else
912 then
923 -- Start of processing for Check_Parameterless_Call
925 begin
926 -- Defend against junk stuff if errors already detected
933 then
940 -- If the context expects a value, and the name is a procedure,
941 -- this is most likely a missing 'Access. Do not try to resolve
942 -- the parameterless call, error will be caught when the outer
943 -- call is analyzed.
948 and then
952 then
956 -- Rewrite as call if overloadable entity that is (or could be, in
957 -- the overloaded case) a function call. If we know for sure that
958 -- the entity is an enumeration literal, we do not rewrite it.
965 -- Rewrite as call if it is an explicit deference of an expression of
966 -- a subprogram access type, and the suprogram type is not that of a
967 -- procedure or entry.
969 or else
972 -- Rewrite as call if it is a selected component which is a function,
973 -- this is the case of a call to a protected function (which may be
974 -- overloaded with other protected operations).
976 or else
979 or else
981 or else
985 -- If one of the above three conditions is met, rewrite as call.
986 -- Apply the rewriting only once.
988 then
991 then
994 -- If overloaded, overload set belongs to new copy
998 -- Change node to parameterless function call (note that the
999 -- Parameter_Associations associations field is left set to Empty,
1000 -- its normal default value since there are no parameters)
1013 -----------------------------
1014 -- Is_Definite_Access_Type --
1015 -----------------------------
1019 begin
1025 ----------------------
1026 -- Is_Predefined_Op --
1027 ----------------------
1030 begin
1038 -----------------------------
1039 -- Make_Call_Into_Operator --
1040 -----------------------------
1042 procedure Make_Call_Into_Operator
1046 is
1061 -- If the operand is not universal, and the operator is given by a
1062 -- expanded name, verify that the operand has an interpretation with
1063 -- a type defined in the given scope of the operator.
1066 -- Find a type of the given class in the package Pack that contains
1067 -- the operator.
1069 ---------------------------
1070 -- Operand_Type_In_Scope --
1071 ---------------------------
1078 begin
1082 else
1096 ---------------
1097 -- Type_In_P --
1098 ---------------
1104 -- Verify that node is not part of the type declaration for the
1105 -- candidate type, which would otherwise be invisible.
1107 -------------
1108 -- In_Decl --
1109 -------------
1115 begin
1124 else
1127 loop
1130 else
1139 -- Start of processing for Type_In_P
1141 begin
1142 -- If the context type is declared in the prefix package, this
1143 -- is the desired base type.
1147 then
1150 else
1154 and then not In_Decl
1155 then
1166 -- Start of processing for Make_Call_Into_Operator
1168 begin
1171 -- Binary operator
1181 -- Unary operator
1183 else
1189 -- If the operator is denoted by an expanded name, and the prefix is
1190 -- not Standard, but the operator is a predefined one whose scope is
1191 -- Standard, then this is an implicit_operator, inserted as an
1192 -- interpretation by the procedure of the same name. This procedure
1193 -- overestimates the presence of implicit operators, because it does
1194 -- not examine the type of the operands. Verify now that the operand
1195 -- type appears in the given scope. If right operand is universal,
1196 -- check the other operand. In the case of concatenation, either
1197 -- argument can be the component type, so check the type of the result.
1198 -- If both arguments are literals, look for a type of the right kind
1199 -- defined in the given scope. This elaborate nonsense is brought to
1200 -- you courtesy of b33302a. The type itself must be frozen, so we must
1201 -- find the type of the proper class in the given scope.
1203 -- A final wrinkle is the multiplication operator for fixed point
1204 -- types, which is defined in Standard only, and not in the scope of
1205 -- the fixed_point type itself.
1210 -- If the entity being called is defined in the given package,
1211 -- it is a renaming of a predefined operator, and known to be
1212 -- legal.
1216 then
1219 -- Visibility does not need to be checked in an instance: if the
1220 -- operator was not visible in the generic it has been diagnosed
1221 -- already, else there is an implicit copy of it in the instance.
1230 then
1235 -- Ada 2005, AI-420: Predefined equality on Universal_Access
1236 -- is available.
1241 then
1244 else
1253 and then Is_Binary
1255 then
1261 -- Verify that the scope contains a type that corresponds to
1262 -- the given literal. Optimize the case where Pack is Standard.
1284 else
1293 else
1302 then
1305 -- If the type is defined elsewhere, and the operator is not
1306 -- defined in the given scope (by a renaming declaration, e.g.)
1307 -- then this is an error as well. If an extension of System is
1308 -- present, and the type may be defined there, Pack must be
1309 -- System itself.
1316 then
1319 else
1325 then
1332 Error_Msg_NE
1343 else
1347 -- If this is a call to a function that renames a predefined equality,
1348 -- the renaming declaration provides a type that must be used to
1349 -- resolve the operands. This must be done now because resolution of
1350 -- the equality node will not resolve any remaining ambiguity, and it
1351 -- assumes that the first operand is not overloaded.
1356 then
1365 -- If this is an arithmetic operator and the result type is private,
1366 -- the operands and the result must be wrapped in conversion to
1367 -- expose the underlying numeric type and expand the proper checks,
1368 -- e.g. on division.
1372 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
1373 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
1382 else
1386 -- For predefined operators on literals, the operation freezes
1387 -- their type.
1395 -------------------
1396 -- Operator_Kind --
1397 -------------------
1399 function Operator_Kind
1402 is
1405 begin
1441 else
1445 -- Unary operators
1447 else
1456 else
1464 -----------------------------
1465 -- Pre_Analyze_And_Resolve --
1466 -----------------------------
1471 begin
1475 -- We suppress all checks for this analysis, since the checks will
1476 -- be applied properly, and in the right location, when the default
1477 -- expression is reanalyzed and reexpanded later on.
1481 Expander_Mode_Restore;
1485 -- Version without context type
1490 begin
1497 Expander_Mode_Restore;
1501 ----------------------------------
1502 -- Replace_Actual_Discriminants --
1503 ----------------------------------
1511 -------------------
1512 -- Process_Discr --
1513 -------------------
1518 begin
1524 then
1540 -- Start of processing for Replace_Actual_Discriminants
1542 begin
1556 else
1561 -------------
1562 -- Resolve --
1563 -------------
1579 -- Determine whether a node comes from a predefined library unit or
1580 -- Standard.
1583 -- Try and fix up a literal so that it matches its expected type. New
1584 -- literals are manufactured if necessary to avoid cascaded errors.
1587 -- Called when attempt at resolving current expression fails
1589 ------------------------------------
1590 -- Comes_From_Predefined_Lib_Unit --
1591 -------------------------------------
1594 begin
1595 return
1601 --------------------
1602 -- Patch_Up_Value --
1603 --------------------
1606 begin
1609 then
1618 then
1626 then
1631 Char_Literal_Value =>
1638 then
1649 -----------------------
1650 -- Resolution_Failed --
1651 -----------------------
1654 begin
1660 -- The caller will return without calling the expander, so we need
1661 -- to set the analyzed flag. Note that it is fine to set Analyzed
1662 -- to True even if we are in the middle of a shallow analysis,
1663 -- (see the spec of sem for more details) since this is an error
1664 -- situation anyway, and there is no point in repeating the
1665 -- analysis later (indeed it won't work to repeat it later, since
1666 -- we haven't got a clear resolution of which entity is being
1667 -- referenced.)
1673 -- Start of processing for Resolve
1675 begin
1680 -- Access attribute on remote subprogram cannot be used for
1681 -- a non-remote access-to-subprogram type.
1692 then
1693 Error_Msg_N
1699 -- If the context is a Remote_Access_To_Subprogram, access attributes
1700 -- must be resolved with the corresponding fat pointer. There is no need
1701 -- to check for the attribute name since the return type of an
1702 -- attribute is never a remote type.
1708 then
1709 declare
1717 begin
1718 -- Check that Typ is a remote access-to-subprogram type
1721 -- Prefix (N) must statically denote a remote subprogram
1722 -- declared in a package specification.
1739 or else
1741 then
1743 Error_Msg_N
1745 N);
1749 -- If we are generating code for a distributed program.
1750 -- perform semantic checks against the corresponding
1751 -- remote entities.
1756 and then Expander_Active
1758 then
1759 Check_Subtype_Conformant
1761 Old_Id => Designated_Type
1782 then
1787 -- Return if already analyzed
1793 -- Return if type = Any_Type (previous error encountered)
1802 -- If not overloaded, then we know the type, and all that needs doing
1803 -- is to check that this type is compatible with the context.
1809 -- In the overloaded case, we must select the interpretation that
1810 -- is compatible with the context (i.e. the type passed to Resolve)
1812 else
1813 -- Loop through possible interpretations
1818 -- We are only interested in interpretations that are compatible
1819 -- with the expected type, any other interpretations are ignored.
1824 Write_Eol;
1827 else
1828 -- Skip the current interpretation if it is disabled by an
1829 -- abstract operator. This action is performed only when the
1830 -- type against which we are resolving is the same as the
1831 -- type of the interpretation.
1838 then
1842 -- First matching interpretation
1850 -- Matching interpretation that is not the first, maybe an
1851 -- error, but there are some cases where preference rules are
1852 -- used to choose between the two possibilities. These and
1853 -- some more obscure cases are handled in Disambiguate.
1855 else
1856 -- If the current statement is part of a predefined library
1857 -- unit, then all interpretations which come from user level
1858 -- packages should not be considered.
1860 if From_Lib
1862 then
1869 -- Disambiguation has succeeded. Skip the remaining
1870 -- interpretations.
1880 else
1881 -- Before we issue an ambiguity complaint, check for
1882 -- the case of a subprogram call where at least one
1883 -- of the arguments is Any_Type, and if so, suppress
1884 -- the message, since it is a cascaded error.
1888 then
1889 declare
1893 begin
1905 Write_Eol;
1918 then
1923 then
1927 -- Not that special case, so issue message using the
1928 -- flag Ambiguous to control printing of the header
1929 -- message only at the start of an ambiguous set.
1934 then
1935 Error_Msg_N
1938 else
1939 Error_Msg_NE
1947 Error_Msg_N
1949 else
1956 -- By default, the error message refers to the candidate
1957 -- interpretation. But if it is a predefined operator, it
1958 -- is implicitly declared at the declaration of the type
1959 -- of the operand. Recover the sloc of that declaration
1960 -- for the error message.
1966 Standard_Standard
1967 then
1972 then
1980 Standard_Standard
1981 then
1986 then
1990 -- If this is an indirect call, use the subprogram_type
1991 -- in the message, to have a meaningful location.
1992 -- Indicate as well if this is an inherited operation,
1993 -- created by a type declaration.
1998 then
2000 Error_Msg_Sloc :=
2002 else
2009 then
2010 -- Special-case the message for universal_fixed
2011 -- operators, which are not declared with the type
2012 -- of the operand, but appear forever in Standard.
2016 then
2017 Error_Msg_N
2021 else
2022 Error_Msg_N
2026 elsif
2028 then
2029 Error_Msg_N
2031 else
2038 -- We have a matching interpretation, Expr_Type is the type
2039 -- from this interpretation, and Seen is the entity.
2041 -- For an operator, just set the entity name. The type will be
2042 -- set by the specific operator resolution routine.
2051 -- For an explicit dereference, attribute reference, range,
2052 -- short-circuit form (which is not an operator node), or call
2053 -- with a name that is an explicit dereference, there is
2054 -- nothing to be done at this point.
2065 then
2068 -- For procedure or function calls, set the type of the name,
2069 -- and also the entity pointer for the prefix
2075 then
2082 then
2087 -- For all other cases, just set the type of the Name
2089 else
2097 -- Move to next interpretation
2105 -- At this stage Found indicates whether or not an acceptable
2106 -- interpretation exists. If not, then we have an error, except
2107 -- that if the context is Any_Type as a result of some other error,
2108 -- then we suppress the error report.
2113 -- If type we are looking for is Void, then this is the procedure
2114 -- call case, and the error is simply that what we gave is not a
2115 -- procedure name (we think of procedure calls as expressions with
2116 -- types internally, but the user doesn't think of them this way!)
2120 -- Special case message if function used as a procedure
2125 then
2126 Error_Msg_NE
2130 -- Otherwise give general message (not clear what cases this
2131 -- covers, but no harm in providing for them!)
2133 else
2139 -- Otherwise we do have a subexpression with the wrong type
2141 -- Check for the case of an allocator which uses an access type
2142 -- instead of the designated type. This is a common error and we
2143 -- specialize the message, posting an error on the operand of the
2144 -- allocator, complaining that we expected the designated type of
2145 -- the allocator.
2151 then
2155 -- Check for view mismatch on Null in instances, for which the
2156 -- view-swapping mechanism has no identifier.
2162 then
2167 -- Check for an aggregate. Sometimes we can get bogus aggregates
2168 -- from misuse of parentheses, and we are about to complain about
2169 -- the aggregate without even looking inside it.
2171 -- Instead, if we have an aggregate of type Any_Composite, then
2172 -- analyze and resolve the component fields, and then only issue
2173 -- another message if we get no errors doing this (otherwise
2174 -- assume that the errors in the aggregate caused the problem).
2178 then
2179 -- Disable expansion in any case. If there is a type mismatch
2180 -- it may be fatal to try to expand the aggregate. The flag
2181 -- would otherwise be set to false when the error is posted.
2185 declare
2187 -- Check one aggregate, and set Found to True if we have a
2188 -- definite error in any of its elements
2191 -- Check one element of aggregate and set Found to True if
2192 -- we definitely have an error in the element.
2194 ----------------
2195 -- Check_Aggr --
2196 ----------------
2201 begin
2214 -- If this is a default-initialized component, then
2215 -- there is nothing to check. The box will be
2216 -- replaced by the appropriate call during late
2217 -- expansion.
2228 ----------------
2229 -- Check_Elmt --
2230 ----------------
2233 begin
2234 -- If we have a nested aggregate, go inside it (to
2235 -- attempt a naked analyze-resolve of the aggregate
2236 -- can cause undesirable cascaded errors). Do not
2237 -- resolve expression if it needs a type from context,
2238 -- as for integer * fixed expression.
2243 else
2248 then
2258 begin
2263 -- If an error message was issued already, Found got reset
2264 -- to True, so if it is still False, issue the standard
2265 -- Wrong_Type message.
2270 then
2271 declare
2273 begin
2279 -- Protected operation: retrieve operation name
2282 else
2292 declare
2296 begin
2303 Error_Msg_NE
2309 else
2312 else
2318 Resolution_Failed;
2321 -- Test if we have more than one interpretation for the context
2324 Resolution_Failed;
2327 -- Here we have an acceptable interpretation for the context
2329 else
2330 -- Propagate type information and normalize tree for various
2331 -- predefined operations. If the context only imposes a class of
2332 -- types, rather than a specific type, propagate the actual type
2333 -- downward.
2340 then
2343 -- Any_Fixed is legal in a real context only if a specific
2344 -- fixed point type is imposed. If Norman Cohen can be
2345 -- confused by this, it deserves a separate message.
2349 then
2356 -- A user-defined operator is tranformed into a function call at
2357 -- this point, so that further processing knows that operators are
2358 -- really operators (i.e. are predefined operators). User-defined
2359 -- operators that are intrinsic are just renamings of the predefined
2360 -- ones, and need not be turned into calls either, but if they rename
2361 -- a different operator, we must transform the node accordingly.
2362 -- Instantiations of Unchecked_Conversion are intrinsic but are
2363 -- treated as functions, even if given an operator designator.
2368 then
2374 and then
2376 = N_Subprogram_Renaming_Declaration
2377 then
2380 -- If the node is rewritten, it will be fully resolved in
2381 -- Rewrite_Renamed_Operator.
2391 when N_Aggregate => Resolve_Aggregate (N, Ctx_Type);
2393 when N_Allocator => Resolve_Allocator (N, Ctx_Type);
2395 when N_And_Then | N_Or_Else
2396 => Resolve_Short_Circuit (N, Ctx_Type);
2398 when N_Attribute_Reference
2399 => Resolve_Attribute (N, Ctx_Type);
2401 when N_Character_Literal
2402 => Resolve_Character_Literal (N, Ctx_Type);
2404 when N_Conditional_Expression
2405 => Resolve_Conditional_Expression (N, Ctx_Type);
2407 when N_Expanded_Name
2408 => Resolve_Entity_Name (N, Ctx_Type);
2410 when N_Extension_Aggregate
2411 => Resolve_Extension_Aggregate (N, Ctx_Type);
2413 when N_Explicit_Dereference
2414 => Resolve_Explicit_Dereference (N, Ctx_Type);
2416 when N_Function_Call
2417 => Resolve_Call (N, Ctx_Type);
2419 when N_Identifier
2420 => Resolve_Entity_Name (N, Ctx_Type);
2422 when N_Indexed_Component
2423 => Resolve_Indexed_Component (N, Ctx_Type);
2425 when N_Integer_Literal
2426 => Resolve_Integer_Literal (N, Ctx_Type);
2428 when N_Membership_Test
2429 => Resolve_Membership_Op (N, Ctx_Type);
2431 when N_Null => Resolve_Null (N, Ctx_Type);
2433 when N_Op_And | N_Op_Or | N_Op_Xor
2434 => Resolve_Logical_Op (N, Ctx_Type);
2436 when N_Op_Eq | N_Op_Ne
2437 => Resolve_Equality_Op (N, Ctx_Type);
2439 when N_Op_Lt | N_Op_Le | N_Op_Gt | N_Op_Ge
2440 => Resolve_Comparison_Op (N, Ctx_Type);
2442 when N_Op_Not => Resolve_Op_Not (N, Ctx_Type);
2444 when N_Op_Add | N_Op_Subtract | N_Op_Multiply |
2445 N_Op_Divide | N_Op_Mod | N_Op_Rem
2447 => Resolve_Arithmetic_Op (N, Ctx_Type);
2449 when N_Op_Concat => Resolve_Op_Concat (N, Ctx_Type);
2451 when N_Op_Expon => Resolve_Op_Expon (N, Ctx_Type);
2453 when N_Op_Plus | N_Op_Minus | N_Op_Abs
2454 => Resolve_Unary_Op (N, Ctx_Type);
2456 when N_Op_Shift => Resolve_Shift (N, Ctx_Type);
2458 when N_Procedure_Call_Statement
2459 => Resolve_Call (N, Ctx_Type);
2461 when N_Operator_Symbol
2462 => Resolve_Operator_Symbol (N, Ctx_Type);
2464 when N_Qualified_Expression
2465 => Resolve_Qualified_Expression (N, Ctx_Type);
2467 when N_Raise_xxx_Error
2468 => Set_Etype (N, Ctx_Type);
2470 when N_Range => Resolve_Range (N, Ctx_Type);
2472 when N_Real_Literal
2473 => Resolve_Real_Literal (N, Ctx_Type);
2475 when N_Reference => Resolve_Reference (N, Ctx_Type);
2477 when N_Selected_Component
2478 => Resolve_Selected_Component (N, Ctx_Type);
2480 when N_Slice => Resolve_Slice (N, Ctx_Type);
2482 when N_String_Literal
2483 => Resolve_String_Literal (N, Ctx_Type);
2485 when N_Subprogram_Info
2486 => Resolve_Subprogram_Info (N, Ctx_Type);
2488 when N_Type_Conversion
2489 => Resolve_Type_Conversion (N, Ctx_Type);
2491 when N_Unchecked_Expression =>
2492 Resolve_Unchecked_Expression (N, Ctx_Type);
2494 when N_Unchecked_Type_Conversion =>
2495 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
2497 end case;
2499 -- If the subexpression was replaced by a non-subexpression, then
2500 -- all we do is to expand it. The only legitimate case we know of
2501 -- is converting procedure call statement to entry call statements,
2502 -- but there may be others, so we are making this test general.
2504 if Nkind (N) not in N_Subexpr then
2505 Debug_A_Exit ("resolving ", N, " (done)");
2506 Expand (N);
2507 return;
2508 end if;
2510 -- The expression is definitely NOT overloaded at this point, so
2511 -- we reset the Is_Overloaded flag to avoid any confusion when
2512 -- reanalyzing the node.
2514 Set_Is_Overloaded (N, False);
2516 -- Freeze expression type, entity if it is a name, and designated
2517 -- type if it is an allocator (RM 13.14(10,11,13)).
2519 -- Now that the resolution of the type of the node is complete,
2520 -- and we did not detect an error, we can expand this node. We
2521 -- skip the expand call if we are in a default expression, see
2522 -- section "Handling of Default Expressions" in Sem spec.
2524 Debug_A_Exit ("resolving ", N, " (done)");
2526 -- We unconditionally freeze the expression, even if we are in
2527 -- default expression mode (the Freeze_Expression routine tests
2528 -- this flag and only freezes static types if it is set).
2530 Freeze_Expression (N);
2532 -- Now we can do the expansion
2534 Expand (N);
2535 end if;
2536 end Resolve;
2538 -------------
2539 -- Resolve --
2540 -------------
2542 -- Version with check(s) suppressed
2544 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
2545 begin
2546 if Suppress = All_Checks then
2547 declare
2548 Svg : constant Suppress_Array := Scope_Suppress;
2549 begin
2550 Scope_Suppress := (others => True);
2551 Resolve (N, Typ);
2552 Scope_Suppress := Svg;
2553 end;
2555 else
2556 declare
2557 Svg : constant Boolean := Scope_Suppress (Suppress);
2558 begin
2559 Scope_Suppress (Suppress) := True;
2560 Resolve (N, Typ);
2561 Scope_Suppress (Suppress) := Svg;
2562 end;
2563 end if;
2564 end Resolve;
2566 -------------
2567 -- Resolve --
2568 -------------
2570 -- Version with implicit type
2572 procedure Resolve (N : Node_Id) is
2573 begin
2574 Resolve (N, Etype (N));
2575 end Resolve;
2577 ---------------------
2578 -- Resolve_Actuals --
2579 ---------------------
2581 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
2582 Loc : constant Source_Ptr := Sloc (N);
2583 A : Node_Id;
2584 F : Entity_Id;
2585 A_Typ : Entity_Id;
2586 F_Typ : Entity_Id;
2587 Prev : Node_Id := Empty;
2588 Orig_A : Node_Id;
2590 procedure Check_Prefixed_Call;
2591 -- If the original node is an overloaded call in prefix notation,
2593 -- Try_Object_Operation has already verified that there is a valid
2594 -- interpretation, but the form of the actual can only be determined
2595 -- once the primitive operation is identified.
2598 -- If the actual is missing in a call, insert in the actuals list
2599 -- an instance of the default expression. The insertion is always
2600 -- a named association.
2603 -- Check whether T1 and T2, or their full views, are derived from a
2604 -- common type. Used to enforce the restrictions on array conversions
2605 -- of AI95-00246.
2607 -------------------------
2608 -- Check_Prefixed_Call --
2609 -------------------------
2618 begin
2619 -- Check whether the call is a prefixed call, with or without
2620 -- additional actuals.
2623 or else
2629 then
2632 then
2633 -- Introduce dereference on object in prefix
2635 New_A :=
2643 then
2644 -- Introduce an implicit 'Access in prefix
2647 Error_Msg_NE
2663 --------------------
2664 -- Insert_Default --
2665 --------------------
2671 begin
2672 -- Missing argument in call, nothing to insert
2677 else
2678 -- Note that we do a full New_Copy_Tree, so that any associated
2679 -- Itypes are properly copied. This may not be needed any more,
2680 -- but it does no harm as a safety measure! Defaults of a generic
2681 -- formal may be out of bounds of the corresponding actual (see
2682 -- cc1311b) and an additional check may be required.
2684 Actval :=
2685 New_Copy_Tree
2692 then
2698 then
2701 then
2702 -- If default is a real literal, do not introduce a
2703 -- conversion whose effect may depend on the run-time
2704 -- size of universal real.
2708 else
2719 -- Resolve aggregates with their base type, to avoid scope
2720 -- anomalies: the subtype was first built in the suprogram
2721 -- declaration, and the current call may be nested.
2725 then
2727 else
2731 else
2734 -- See note above concerning aggregates
2738 then
2741 -- Resolve entities with their own type, which may differ
2742 -- from the type of a reference in a generic context (the
2743 -- view swapping mechanism did not anticipate the re-analysis
2744 -- of default values in calls).
2749 else
2754 -- If default is a tag indeterminate function call, propagate
2755 -- tag to obtain proper dispatching.
2759 then
2765 -- If the default expression raises constraint error, then just
2766 -- silently replace it with an N_Raise_Constraint_Error node,
2767 -- since we already gave the warning on the subprogram spec.
2777 Assoc :=
2782 -- Case of insertion is first named actual
2786 then
2793 else
2797 else
2801 -- Case of insertion is not first named actual
2803 else
2804 Set_Next_Named_Actual
2816 -------------------
2817 -- Same_Ancestor --
2818 -------------------
2824 begin
2827 then
2833 then
2840 -- Start of processing for Resolve_Actuals
2842 begin
2844 Check_Prefixed_Call;
2853 -- If we have an error in any actual or formal, indicated by
2854 -- a type of Any_Type, then abandon resolution attempt, and
2855 -- set result type to Any_Type.
2859 then
2864 -- Case where actual is present
2866 -- If the actual is an entity, generate a reference to it now. We
2867 -- do this before the actual is resolved, because a formal of some
2868 -- protected subprogram, or a task discriminant, will be rewritten
2869 -- during expansion, and the reference to the source entity may
2870 -- be lost.
2875 then
2881 then
2892 or else
2894 then
2895 -- If the formal is Out or In_Out, do not resolve and expand the
2896 -- conversion, because it is subsequently expanded into explicit
2897 -- temporaries and assignments. However, the object of the
2898 -- conversion can be resolved. An exception is the case of tagged
2899 -- type conversion with a class-wide actual. In that case we want
2900 -- the tag check to occur and no temporary will be needed (no
2901 -- representation change can occur) and the parameter is passed by
2902 -- reference, so we go ahead and resolve the type conversion.
2903 -- Another exception is the case of reference to component or
2904 -- subcomponent of a bit-packed array, in which case we want to
2905 -- defer expansion to the point the in and out assignments are
2906 -- performed.
2911 then
2914 then
2917 then
2919 Error_Msg_N
2923 -- Ada 2005: rule is relaxed (see AI-363)
2926 and then
2928 then
2929 Error_Msg_N
2932 Error_Msg_N
2937 and then
2940 then
2941 Error_Msg_N
2950 then
2954 -- If the actual is a function call that returns a limited
2955 -- unconstrained object that needs finalization, create a
2956 -- transient scope for it, so that it can receive the proper
2957 -- finalization list.
2962 and then Expander_Active
2963 and then
2965 then
2968 else
2972 and then
2975 then
2976 Error_Msg_N
2989 -- (Ada 2005: AI-251): If the actual is an allocator whose
2990 -- directly designated type is a class-wide interface, we build
2991 -- an anonymous access type to use it as the type of the
2992 -- allocator. Later, when the subprogram call is expanded, if
2993 -- the interface has a secondary dispatch table the expander
2994 -- will add a type conversion to force the correct displacement
2995 -- of the pointer.
2998 declare
3002 begin
3005 then
3014 -- Ada 2005, AI-162:If the actual is an allocator, the
3015 -- innermost enclosing statement is the master of the
3016 -- created object. This needs to be done with expansion
3017 -- enabled only, otherwise the transient scope will not
3018 -- be removed in the expansion of the wrapped construct.
3022 and then Expander_Active
3023 then
3029 -- (Ada 2005): The call may be to a primitive operation of
3030 -- a tagged synchronized type, declared outside of the type.
3031 -- In this case the controlling actual must be converted to
3032 -- its corresponding record type, which is the formal type.
3036 then
3038 Unchecked_Convert_To
3048 -- Perform error checks for IN and IN OUT parameters
3052 -- Check unset reference. For scalar parameters, it is clearly
3053 -- wrong to pass an uninitialized value as either an IN or
3054 -- IN-OUT parameter. For composites, it is also clearly an
3055 -- error to pass a completely uninitialized value as an IN
3056 -- parameter, but the case of IN OUT is trickier. We prefer
3057 -- not to give a warning here. For example, suppose there is
3058 -- a routine that sets some component of a record to False.
3059 -- It is perfectly reasonable to make this IN-OUT and allow
3060 -- either initialized or uninitialized records to be passed
3061 -- in this case.
3063 -- For partially initialized composite values, we also avoid
3064 -- warnings, since it is quite likely that we are passing a
3065 -- partially initialized value and only the initialized fields
3066 -- will in fact be read in the subprogram.
3071 then
3075 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
3076 -- actual to a nested call, since this is case of reading an
3077 -- out parameter, which is not allowed.
3082 then
3087 -- Case of OUT or IN OUT parameter
3091 -- For an Out parameter, check for useless assignment. Note
3092 -- that we can't set Last_Assignment this early, because we
3093 -- may kill current values in Resolve_Call, and that call
3094 -- would clobber the Last_Assignment field.
3096 -- Note: call Warn_On_Useless_Assignment before doing the
3097 -- check below for Is_OK_Variable_For_Out_Formal so that the
3098 -- setting of Referenced_As_LHS/Referenced_As_Out_Formal
3099 -- properly reflects the last assignment, not this one!
3106 then
3111 -- Validate the form of the actual. Note that the call to
3112 -- Is_OK_Variable_For_Out_Formal generates the required
3113 -- reference in this case.
3119 -- What's the following about???
3123 else
3124 Kill_All_Checks;
3133 -- Apply appropriate range checks for in, out, and in-out
3134 -- parameters. Out and in-out parameters also need a separate
3135 -- check, if there is a type conversion, to make sure the return
3136 -- value meets the constraints of the variable before the
3137 -- conversion.
3139 -- Gigi looks at the check flag and uses the appropriate types.
3140 -- For now since one flag is used there is an optimization which
3141 -- might not be done in the In Out case since Gigi does not do
3142 -- any analysis. More thought required about this ???
3146 then
3158 then
3164 then
3170 then
3173 else
3177 -- Ada 2005 (AI-231)
3183 then
3184 Apply_Compile_Time_Constraint_Error
3194 then
3197 Apply_Scalar_Range_Check
3199 else
3200 Apply_Range_Check
3204 else
3210 then
3213 else
3219 -- An actual associated with an access parameter is implicitly
3220 -- converted to the anonymous access type of the formal and
3221 -- must satisfy the legality checks for access conversions.
3225 Error_Msg_N
3230 -- Check bad case of atomic/volatile argument (RM C.6(12))
3234 then
3237 then
3238 Error_Msg_N
3240 N);
3244 then
3245 Error_Msg_N
3247 N);
3251 -- Check that subprograms don't have improper controlling
3252 -- arguments (RM 3.9.2 (9))
3254 -- A primitive operation may have an access parameter of an
3255 -- incomplete tagged type, but a dispatching call is illegal
3256 -- if the type is still incomplete.
3262 declare
3264 begin
3268 then
3269 Error_Msg_NE
3283 then
3288 then
3290 Error_Msg_NE
3300 and then
3304 then
3305 Error_Msg_N
3310 then
3312 Error_Msg_NE
3319 -- If it is a named association, treat the selector_name as
3320 -- a proper identifier, and mark the corresponding entity.
3337 -- Case where actual is not present
3339 else
3340 Insert_Default;
3347 -----------------------
3348 -- Resolve_Allocator --
3349 -----------------------
3360 procedure Check_Allocator_Discrim_Accessibility
3363 -- Check that accessibility level associated with an access discriminant
3364 -- initialized in an allocator by the expression Disc_Exp is not deeper
3365 -- than the level of the allocator type Alloc_Typ. An error message is
3366 -- issued if this condition is violated. Specialized checks are done for
3367 -- the cases of a constraint expression which is an access attribute or
3368 -- an access discriminant.
3371 -- If the allocator is an actual in a call, it is allowed to be class-
3372 -- wide when the context is not because it is a controlling actual.
3375 -- Propagate all nested coextensions which are located one nesting
3376 -- level down the tree to the node Root. Example:
3377 --
3378 -- Top_Record
3379 -- Level_1_Coextension
3380 -- Level_2_Coextension
3381 --
3382 -- The algorithm is paired with delay actions done by the Expander. In
3383 -- the above example, assume all coextensions are controlled types.
3384 -- The cycle of analysis, resolution and expansion will yield:
3385 --
3386 -- 1) Analyze Top_Record
3387 -- 2) Analyze Level_1_Coextension
3388 -- 3) Analyze Level_2_Coextension
3389 -- 4) Resolve Level_2_Coextnesion. The allocator is marked as a
3390 -- coextension.
3391 -- 5) Expand Level_2_Coextension. A temporary variable Temp_1 is
3392 -- generated to capture the allocated object. Temp_1 is attached
3393 -- to the coextension chain of Level_2_Coextension.
3394 -- 6) Resolve Level_1_Coextension. The allocator is marked as a
3395 -- coextension. A forward tree traversal is performed which finds
3396 -- Level_2_Coextension's list and copies its contents into its
3397 -- own list.
3398 -- 7) Expand Level_1_Coextension. A temporary variable Temp_2 is
3399 -- generated to capture the allocated object. Temp_2 is attached
3400 -- to the coextension chain of Level_1_Coextension. Currently, the
3401 -- contents of the list are [Temp_2, Temp_1].
3402 -- 8) Resolve Top_Record. A forward tree traversal is performed which
3403 -- finds Level_1_Coextension's list and copies its contents into
3404 -- its own list.
3405 -- 9) Expand Top_Record. Generate finalization calls for Temp_1 and
3406 -- Temp_2 and attach them to Top_Record's finalization list.
3408 -------------------------------------------
3409 -- Check_Allocator_Discrim_Accessibility --
3410 -------------------------------------------
3412 procedure Check_Allocator_Discrim_Accessibility
3415 is
3416 begin
3419 then
3420 Error_Msg_N
3423 -- When the expression is an Access attribute the level of the prefix
3424 -- object must not be deeper than that of the allocator's type.
3428 = Attribute_Access
3431 then
3432 Error_Msg_N
3434 Disc_Exp);
3436 -- When the expression is an access discriminant the check is against
3437 -- the level of the prefix object.
3443 then
3444 Error_Msg_N
3446 Disc_Exp);
3448 -- All other cases are legal
3450 else
3455 ----------------------------
3456 -- In_Dispatching_Context --
3457 ----------------------------
3461 begin
3468 ----------------------------
3469 -- Propagate_Coextensions --
3470 ----------------------------
3475 -- Copy the contents of list From into list To, preserving the
3476 -- order of elements.
3479 -- Recognize an allocator or a rewritten allocator node and add it
3480 -- allong with its nested coextensions to the list of Root.
3482 ---------------
3483 -- Copy_List --
3484 ---------------
3488 begin
3496 -----------------------
3497 -- Process_Allocator --
3498 -----------------------
3503 begin
3504 -- This is a possible rewritten subtype indication allocator. Any
3505 -- nested coextensions will appear as discriminant constraints.
3510 then
3511 declare
3515 begin
3517 Discr_Elmt :=
3527 then
3532 Copy_List
3540 -- There is no need to continue the traversal of this
3541 -- subtree since all the information has already been
3542 -- propagated.
3548 -- Case of either a stand alone allocator or a rewritten allocator
3549 -- with an aggregate.
3551 else
3558 -- Propagate the list of nested coextensions to the Root
3559 -- allocator. This is done through list copy since a single
3560 -- allocator may have multiple coextensions. Do not touch
3561 -- coextensions roots.
3565 then
3570 Copy_List
3575 -- There is no need to continue the traversal of this
3576 -- subtree since all the information has already been
3577 -- propagated.
3583 -- Keep on traversing, looking for the next allocator
3591 -- Start of processing for Propagate_Coextensions
3593 begin
3597 -- Start of processing for Resolve_Allocator
3599 begin
3600 -- Replace general access with specific type
3610 -- For qualified expression, resolve the expression using the
3611 -- given subtype (nothing to do for type mark, subtype indication)
3616 and then not In_Dispatching_Context
3617 then
3618 Error_Msg_N
3625 -- A qualified expression requires an exact match of the type,
3626 -- class-wide matching is not allowed.
3631 then
3635 -- A special accessibility check is needed for allocators that
3636 -- constrain access discriminants. The level of the type of the
3637 -- expression used to constrain an access discriminant cannot be
3638 -- deeper than the type of the allocator (in constrast to access
3639 -- parameters, where the level of the actual can be arbitrary).
3641 -- We can't use Valid_Conversion to perform this check because
3642 -- in general the type of the allocator is unrelated to the type
3643 -- of the access discriminant.
3647 then
3653 and then
3655 or else
3657 then
3660 -- Get the first component expression of the aggregate
3670 else
3674 else
3693 else
3698 else
3707 -- For a subtype mark or subtype indication, freeze the subtype
3709 else
3713 Error_Msg_N
3717 -- A special accessibility check is needed for allocators that
3718 -- constrain access discriminants. The level of the type of the
3719 -- expression used to constrain an access discriminant cannot be
3720 -- deeper than the type of the allocator (in constrast to access
3721 -- parameters, where the level of the actual can be arbitrary).
3722 -- We can't use Valid_Conversion to perform this check because
3723 -- in general the type of the allocator is unrelated to the type
3724 -- of the access discriminant.
3729 then
3739 else
3753 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
3754 -- check that the level of the type of the created object is not deeper
3755 -- than the level of the allocator's access type, since extensions can
3756 -- now occur at deeper levels than their ancestor types. This is a
3757 -- static accessibility level check; a run-time check is also needed in
3758 -- the case of an initialized allocator with a class-wide argument (see
3759 -- Expand_Allocator_Expression).
3763 then
3764 declare
3767 begin
3772 else
3781 E);
3787 -- Do not apply Ada 2005 accessibility checks on a class-wide
3788 -- allocator if the type given in the allocator is a formal
3789 -- type. A run-time check will be performed in the instance.
3799 -- Check for allocation from an empty storage pool
3802 declare
3804 begin
3812 -- If the context is an unchecked conversion, as may happen within
3813 -- an inlined subprogram, the allocator is being resolved with its
3814 -- own anonymous type. In that case, if the target type has a specific
3815 -- storage pool, it must be inherited explicitly by the allocator type.
3819 then
3820 Set_Associated_Storage_Pool
3824 -- An erroneous allocator may be rewritten as a raise Program_Error
3825 -- statement.
3829 -- An anonymous access discriminant is the definition of a
3830 -- coextension.
3834 N_Discriminant_Specification
3835 then
3836 -- Avoid marking an allocator as a dynamic coextension if it is
3837 -- within a static construct.
3843 -- Cleanup for potential static coextensions
3845 else
3850 -- There is no need to propagate any nested coextensions if they
3851 -- are marked as static since they will be rewritten on the spot.
3859 ---------------------------
3860 -- Resolve_Arithmetic_Op --
3861 ---------------------------
3863 -- Used for resolving all arithmetic operators except exponentiation
3874 -- We do the resolution using the base type, because intermediate values
3875 -- in expressions always are of the base type, not a subtype of it.
3878 -- Returns True if N is in a context that expects "any real type"
3881 -- Return True iff given type is Integer or universal real/integer
3884 -- Choose type of integer literal in fixed-point operation to conform
3885 -- to available fixed-point type. T is the type of the other operand,
3886 -- which is needed to determine the expected type of N.
3889 -- Set operand type to T if universal
3891 -------------------------------
3892 -- Expected_Type_Is_Any_Real --
3893 -------------------------------
3896 begin
3897 -- N is the expression after "delta" in a fixed_point_definition;
3898 -- see RM-3.5.9(6):
3903 -- N is one of the bounds in a real_range_specification;
3904 -- see RM-3.5.7(5):
3908 -- N is the expression of a delta_constraint;
3909 -- see RM-J.3(3):
3914 -----------------------------
3915 -- Is_Integer_Or_Universal --
3916 -----------------------------
3923 begin
3929 else
3935 then
3946 ----------------------------
3947 -- Set_Mixed_Mode_Operand --
3948 ----------------------------
3954 begin
3957 -- A universal integer literal is resolved as standard integer
3958 -- except in the case of a fixed-point result, where we leave it
3959 -- as universal (to be handled by Exp_Fixd later on)
3963 else
3971 then
3972 -- A universal real can appear in a fixed-type context. We resolve
3973 -- the literal with that context, even though this might raise an
3974 -- exception prematurely (the other operand may be zero).
3981 then
3982 -- Integer arg in mixed-mode operation. Resolve with universal
3983 -- type, in case preference rule must be applied.
3989 then
3990 -- Not a mixed-mode operation, resolve with context
3996 -- N may itself be a mixed-mode operation, so use context type
4003 then
4004 -- Must be (fixed * fixed) operation, operand must have one
4005 -- compatible interpretation.
4013 then
4014 -- C * F(X) in a fixed context, where C is a real literal or a
4015 -- fixed-point expression. F must have either a fixed type
4016 -- interpretation or an integer interpretation, but not both.
4024 else
4032 else
4040 -- Reanalyze the literal with the fixed type of the context. If
4041 -- context is Universal_Fixed, we are within a conversion, leave
4042 -- the literal as a universal real because there is no usable
4043 -- fixed type, and the target of the conversion plays no role in
4044 -- the resolution.
4046 declare
4050 begin
4053 else
4059 then
4061 else
4069 else
4074 ----------------------
4075 -- Set_Operand_Type --
4076 ----------------------
4079 begin
4082 then
4087 -- Start of processing for Resolve_Arithmetic_Op
4089 begin
4094 then
4098 -- Special-case for mixed-mode universal expressions or fixed point
4099 -- type operation: each argument is resolved separately. The same
4100 -- treatment is required if one of the operands of a fixed point
4101 -- operation is universal real, since in this case we don't do a
4102 -- conversion to a specific fixed-point type (instead the expander
4103 -- takes care of the case).
4109 then
4120 or else
4124 then
4129 -- If context is a fixed type and one operand is integer, the
4130 -- other is resolved with the type of the context.
4135 then
4142 then
4146 else
4151 -- Check the rule in RM05-4.5.5(19.1/2) disallowing the
4152 -- universal_fixed multiplying operators from being used when the
4153 -- expected type is also universal_fixed. Note that B_Typ will be
4154 -- Universal_Fixed in some cases where the expected type is actually
4155 -- Any_Real; Expected_Type_Is_Any_Real takes care of that case.
4159 then
4164 then
4165 Error_Msg_N
4167 Error_Msg_N
4173 else
4178 then
4179 Error_Msg_N
4182 N);
4185 -- The expected type is "any real type" in contexts like
4186 -- type T is delta <universal_fixed-expression> ...
4187 -- in which case we need to set the type to Universal_Real
4188 -- so that static expression evaluation will work properly.
4192 else
4201 or else
4203 then
4208 -- If no previous errors, this is only possible if one operand
4209 -- is overloaded and the context is universal. Resolve as such.
4214 else
4217 then
4221 -- If the context is Universal_Fixed and the operands are also
4222 -- universal fixed, this is an error, unless there is only one
4223 -- applicable fixed_point type (usually duration).
4227 then
4233 else
4238 else
4243 -- If one of the arguments was resolved to a non-universal type.
4244 -- label the result of the operation itself with the same type.
4245 -- Do the same for the universal argument, if any.
4256 -- Set overflow and division checking bit. Much cleverer code needed
4257 -- here eventually and perhaps the Resolve routines should be separated
4258 -- for the various arithmetic operations, since they will need
4259 -- different processing. ???
4266 -- Give warning if explicit division by zero
4272 then
4278 or else
4281 then
4282 -- Specialize the warning message according to the operation
4286 Apply_Compile_Time_Constraint_Error
4291 Apply_Compile_Time_Constraint_Error
4296 Apply_Compile_Time_Constraint_Error
4300 -- Division by zero can only happen with division, rem,
4301 -- and mod operations.
4307 -- Otherwise just set the flag to check at run time
4309 else
4319 ------------------
4320 -- Resolve_Call --
4321 ------------------
4333 begin
4334 -- The context imposes a unique interpretation with type Typ on a
4335 -- procedure or function call. Find the entity of the subprogram that
4336 -- yields the expected type, and propagate the corresponding formal
4337 -- constraints on the actuals. The caller has established that an
4338 -- interpretation exists, and emitted an error if not unique.
4340 -- First deal with the case of a call to an access-to-subprogram,
4341 -- dereference made explicit in Analyze_Call.
4347 else
4348 -- Find the interpretation whose type (a subprogram type) has a
4349 -- return type that is compatible with the context. Analysis of
4350 -- the node has established that one exists.
4369 -- If the prefix is not an entity, then resolve it
4375 -- For an indirect call, we always invalidate checks, since we do not
4376 -- know whether the subprogram is local or global. Yes we could do
4377 -- better here, e.g. by knowing that there are no local subprograms,
4378 -- but it does not seem worth the effort. Similarly, we kill all
4379 -- knowledge of current constant values.
4381 Kill_Current_Values;
4383 -- If this is a procedure call which is really an entry call, do
4384 -- the conversion of the procedure call to an entry call. Protected
4385 -- operations use the same circuitry because the name in the call
4386 -- can be an arbitrary expression with special resolution rules.
4392 then
4396 -- Kill checks and constant values, as above for indirect case
4397 -- Who knows what happens when another task is activated?
4399 Kill_Current_Values;
4402 -- Normal subprogram call with name established in Resolve
4408 -- Otherwise we must have the case of an overloaded call
4410 else
4426 -- Check that a call to Current_Task does not occur in an entry body
4429 declare
4432 begin
4434 loop
4441 then
4443 Error_Msg_NE
4446 Error_Msg_NE
4458 -- Check that a procedure call does not occur in the context of the
4459 -- entry call statement of a conditional or timed entry call. Note that
4460 -- the case of a call to a subprogram renaming of an entry will also be
4461 -- rejected. The test for N not being an N_Entry_Call_Statement is
4462 -- defensive, covering the possibility that the processing of entry
4463 -- calls might reach this point due to later modifications of the code
4464 -- above.
4469 then
4473 -- Ada 2005 (AI-345): If a procedure_call_statement is used
4474 -- for a procedure_or_entry_call, the procedure_name or pro-
4475 -- cedure_prefix of the procedure_call_statement shall denote
4476 -- an entry renamed by a procedure, or (a view of) a primitive
4477 -- subprogram of a limited interface whose first parameter is
4478 -- a controlling parameter.
4483 then
4484 Error_Msg_N
4489 -- Check that this is not a call to a protected procedure or
4490 -- entry from within a protected function.
4496 then
4502 -- Freeze the subprogram name if not in default expression. Note that we
4503 -- freeze procedure calls as well as function calls. Procedure calls are
4504 -- not frozen according to the rules (RM 13.14(14)) because it is
4505 -- impossible to have a procedure call to a non-frozen procedure in pure
4506 -- Ada, but in the code that we generate in the expander, this rule
4507 -- needs extending because we can generate procedure calls that need
4508 -- freezing.
4514 -- For a predefined operator, the type of the result is the type imposed
4515 -- by context, except for a predefined operation on universal fixed.
4516 -- Otherwise The type of the call is the type returned by the subprogram
4517 -- being called.
4524 -- If the subprogram returns an array type, and the context requires the
4525 -- component type of that array type, the node is really an indexing of
4526 -- the parameterless call. Resolve as such. A pathological case occurs
4527 -- when the type of the component is an access to the array type. In
4528 -- this case the call is truly ambiguous.
4531 and then
4536 and then
4539 then
4540 declare
4545 begin
4548 then
4549 Error_Msg_N
4551 else
4558 -- Indexed call to a parameterless function
4560 Index_Node :=
4562 Prefix =>
4566 else
4567 -- An Ada 2005 prefixed call to a primitive operation
4568 -- whose first parameter is the prefix. This prefix was
4569 -- prepended to the parameter list, which is actually a
4570 -- list of indices. Remove the prefix in order to build
4571 -- the proper indexed component.
4573 Index_Node :=
4575 Prefix =>
4578 Parameter_Associations =>
4579 New_List
4584 -- Since we are correcting a node classification error made
4585 -- by the parser, we call Replace rather than Rewrite.
4598 else
4602 -- In the case where the call is to an overloaded subprogram, Analyze
4603 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
4604 -- such a case Normalize_Actuals needs to be called once more to order
4605 -- the actuals correctly. Otherwise the call will have the ordering
4606 -- given by the last overloaded subprogram whether this is the correct
4607 -- one being called or not.
4614 -- In any case, call is fully resolved now. Reset Overload flag, to
4615 -- prevent subsequent overload resolution if node is analyzed again
4620 -- If we are calling the current subprogram from immediately within its
4621 -- body, then that is the case where we can sometimes detect cases of
4622 -- infinite recursion statically. Do not try this in case restriction
4623 -- No_Recursion is in effect anyway, and do it only for source calls.
4631 then
4632 -- Here we detected and flagged an infinite recursion, so we do
4633 -- not need to test the case below for further warnings.
4637 -- If call is to immediately containing subprogram, then check for
4638 -- the case of a possible run-time detectable infinite recursion.
4640 else
4644 -- Although in general case, recursion is not statically
4645 -- checkable, the case of calling an immediately containing
4646 -- subprogram is easy to catch.
4650 -- If the recursive call is to a parameterless subprogram,
4651 -- then even if we can't statically detect infinite
4652 -- recursion, this is pretty suspicious, and we output a
4653 -- warning. Furthermore, we will try later to detect some
4654 -- cases here at run time by expanding checking code (see
4655 -- Detect_Infinite_Recursion in package Exp_Ch6).
4657 -- If the recursive call is within a handler, do not emit a
4658 -- warning, because this is a common idiom: loop until input
4659 -- is correct, catch illegal input in handler and restart.
4665 then
4666 -- For the case of a procedure call. We give the message
4667 -- only if the call is the first statement in a sequence
4668 -- of statements, or if all previous statements are
4669 -- simple assignments. This is simply a heuristic to
4670 -- decrease false positives, without losing too many good
4671 -- warnings. The idea is that these previous statements
4672 -- may affect global variables the procedure depends on.
4676 then
4677 declare
4679 begin
4691 -- Do not give warning if we are in a conditional context
4693 declare
4695 begin
4701 then
4706 -- Here warning is to be issued
4709 Error_Msg_N
4711 Error_Msg_N
4723 -- If subprogram name is a predefined operator, it was given in
4724 -- functional notation. Replace call node with operator node, so
4725 -- that actuals can be resolved appropriately.
4733 then
4739 -- Create a transient scope if the resulting type requires it
4741 -- There are 4 notable exceptions: in init procs, the transient scope
4742 -- overhead is not needed and even incorrect due to the actual expansion
4743 -- of adjust calls; the second case is enumeration literal pseudo calls;
4744 -- the third case is intrinsic subprograms (Unchecked_Conversion and
4745 -- source information functions) that do not use the secondary stack
4746 -- even though the return type is unconstrained; the fourth case is a
4747 -- call to a build-in-place function, since such functions may allocate
4748 -- their result directly in a target object, and cases where the result
4749 -- does get allocated in the secondary stack are checked for within the
4750 -- specialized Exp_Ch6 procedures for expanding build-in-place calls.
4752 -- If this is an initialization call for a type whose initialization
4753 -- uses the secondary stack, we also need to create a transient scope
4754 -- for it, precisely because we will not do it within the init proc
4755 -- itself.
4757 -- If the subprogram is marked Inline_Always, then even if it returns
4758 -- an unconstrained type the call does not require use of the secondary
4759 -- stack.
4765 then
4768 elsif Expander_Active
4773 and then not Within_Init_Proc
4775 then
4778 -- If the call appears within the bounds of a loop, it will
4779 -- be rewritten and reanalyzed, nothing left to do here.
4786 and then not Within_Init_Proc
4787 then
4791 -- A protected function cannot be called within the definition of the
4792 -- enclosing protected type.
4797 then
4798 Error_Msg_NE
4802 -- Propagate interpretation to actuals, and add default expressions
4803 -- where needed.
4808 -- Overloaded literals are rewritten as function calls, for
4809 -- purpose of resolution. After resolution, we can replace
4810 -- the call with the literal itself.
4816 -- Avoid validation, since it is a static function call
4822 -- If the subprogram is not global, then kill all saved values and
4823 -- checks. This is a bit conservative, since in many cases we could do
4824 -- better, but it is not worth the effort. Similarly, we kill constant
4825 -- values. However we do not need to do this for internal entities
4826 -- (unless they are inherited user-defined subprograms), since they
4827 -- are not in the business of molesting local values.
4829 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
4830 -- kill all checks and values for calls to global subprograms. This
4831 -- takes care of the case where an access to a local subprogram is
4832 -- taken, and could be passed directly or indirectly and then called
4833 -- from almost any context.
4835 -- Note: we do not do this step till after resolving the actuals. That
4836 -- way we still take advantage of the current value information while
4837 -- scanning the actuals.
4844 then
4845 Kill_Current_Values;
4848 -- If we are warning about unread OUT parameters, this is the place to
4849 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
4850 -- after the above call to Kill_Current_Values (since that call clears
4851 -- the Last_Assignment field of all local variables).
4856 then
4857 declare
4861 begin
4872 then
4882 -- If the subprogram is a primitive operation, check whether or not
4883 -- it is a correct dispatching call.
4887 then
4892 and then not In_Instance
4893 then
4897 -- If this is a dispatching call, generate the appropriate reference,
4898 -- for better source navigation in GPS.
4902 then
4904 else
4912 -- All done, evaluate call and deal with elaboration issues
4918 -------------------------------
4919 -- Resolve_Character_Literal --
4920 -------------------------------
4926 begin
4927 -- Verify that the character does belong to the type of the context
4932 -- Wide_Wide_Character literals must always be defined, since the set
4933 -- of wide wide character literals is complete, i.e. if a character
4934 -- literal is accepted by the parser, then it is OK for wide wide
4935 -- character (out of range character literals are rejected).
4940 -- Always accept character literal for type Any_Character, which
4941 -- occurs in error situations and in comparisons of literals, both
4942 -- of which should accept all literals.
4947 -- For Standard.Character or a type derived from it, check that
4948 -- the literal is in range
4955 -- For Standard.Wide_Character or a type derived from it, check
4956 -- that the literal is in range
4963 -- For Standard.Wide_Wide_Character or a type derived from it, we
4964 -- know the literal is in range, since the parser checked!
4969 -- If the entity is already set, this has already been resolved in
4970 -- a generic context, or comes from expansion. Nothing else to do.
4975 -- Otherwise we have a user defined character type, and we can use
4976 -- the standard visibility mechanisms to locate the referenced entity
4978 else
4991 -- If we fall through, then the literal does not match any of the
4992 -- entries of the enumeration type. This isn't just a constraint
4993 -- error situation, it is an illegality (see RM 4.2).
4995 Error_Msg_NE
4999 ---------------------------
5000 -- Resolve_Comparison_Op --
5001 ---------------------------
5003 -- Context requires a boolean type, and plays no role in resolution.
5004 -- Processing identical to that for equality operators. The result
5005 -- type is the base type, which matters when pathological subtypes of
5006 -- booleans with limited ranges are used.
5013 begin
5014 -- If this is an intrinsic operation which is not predefined, use
5015 -- the types of its declared arguments to resolve the possibly
5016 -- overloaded operands. Otherwise the operands are unambiguous and
5017 -- specify the expected type.
5022 else
5037 then
5040 else
5047 else
5058 ------------------------------------
5059 -- Resolve_Conditional_Expression --
5060 ------------------------------------
5067 begin
5076 -----------------------------------------
5077 -- Resolve_Discrete_Subtype_Indication --
5078 -----------------------------------------
5080 procedure Resolve_Discrete_Subtype_Indication
5083 is
5087 begin
5095 else
5105 Error_Msg_NE
5108 -- Rewrite the constraint as a range of Typ
5109 -- to allow compilation to proceed further.
5121 else
5125 -- Additionally, we must check that the bounds are compatible
5126 -- with the given subtype, which might be different from the
5127 -- type of the context.
5131 -- ??? If the above check statically detects a Constraint_Error
5132 -- it replaces the offending bound(s) of the range R with a
5133 -- Constraint_Error node. When the itype which uses these bounds
5134 -- is frozen the resulting call to Duplicate_Subexpr generates
5135 -- a new temporary for the bounds.
5137 -- Unfortunately there are other itypes that are also made depend
5138 -- on these bounds, so when Duplicate_Subexpr is called they get
5139 -- a forward reference to the newly created temporaries and Gigi
5140 -- aborts on such forward references. This is probably sign of a
5141 -- more fundamental problem somewhere else in either the order of
5142 -- itype freezing or the way certain itypes are constructed.
5144 -- To get around this problem we call Remove_Side_Effects right
5145 -- away if either bounds of R are a Constraint_Error.
5147 declare
5151 begin
5167 -------------------------
5168 -- Resolve_Entity_Name --
5169 -------------------------
5171 -- Used to resolve identifiers and expanded names
5176 begin
5177 -- If garbage from errors, set to Any_Type and return
5184 -- Replace named numbers by corresponding literals. Note that this is
5185 -- the one case where Resolve_Entity_Name must reset the Etype, since
5186 -- it is currently marked as universal.
5196 -- Allow use of subtype only if it is a concurrent type where we are
5197 -- currently inside the body. This will eventually be expanded
5198 -- into a call to Self (for tasks) or _object (for protected
5199 -- objects). Any other use of a subtype is invalid.
5204 then
5206 else
5207 Error_Msg_N
5211 -- Check discriminant use if entity is discriminant in current scope,
5212 -- i.e. discriminant of record or concurrent type currently being
5213 -- analyzed. Uses in corresponding body are unrestricted.
5218 then
5221 -- A parameterless generic function cannot appear in a context that
5222 -- requires resolution.
5233 then
5236 -- In all other cases, just do the possible static evaluation
5238 else
5239 -- A deferred constant that appears in an expression must have
5240 -- a completion, unless it has been removed by in-place expansion
5241 -- of an aggregate.
5247 and then not In_Default_Expression
5249 then
5254 then
5256 else
5257 Error_Msg_N (
5266 -------------------
5267 -- Resolve_Entry --
5268 -------------------
5280 -- If the bounds of the entry family being called depend on task
5281 -- discriminants, build a new index subtype where a discriminant is
5282 -- replaced with the value of the discriminant of the target task.
5283 -- The target task is the prefix of the entry name in the call.
5285 -----------------------
5286 -- Actual_Index_Type --
5287 -----------------------
5297 -- If the bound is given by a discriminant, replace with a reference
5298 -- to the discriminant of the same name in the target task.
5299 -- If the entry name is the target of a requeue statement and the
5300 -- entry is in the current protected object, the bound to be used
5301 -- is the discriminal of the object (see apply_range_checks for
5302 -- details of the transformation).
5304 -----------------------------
5305 -- Actual_Discriminant_Ref --
5306 -----------------------------
5312 begin
5317 then
5323 then
5326 else
5327 Ref :=
5337 -- Start of processing for Actual_Index_Type
5339 begin
5343 then
5346 else
5360 -- Start of processing of Resolve_Entry
5362 begin
5363 -- Find name of entry being called, and resolve prefix of name
5364 -- with its own type. The prefix can be overloaded, and the name
5365 -- and signature of the entry must be taken into account.
5369 -- Case of dealing with entry family within the current tasks
5373 else
5378 -- Entry call to an entry (or entry family) in the current task.
5379 -- This is legal even though the task will deadlock. Rewrite as
5380 -- call to current task.
5382 -- This can also be a call to an entry in an enclosing task.
5383 -- If this is a single task, we have to retrieve its name,
5384 -- because the scope of the entry is the task type, not the
5385 -- object. If the enclosing task is a task type, the identity
5386 -- of the task is given by its own self variable.
5388 -- Finally this can be a requeue on an entry of the same task
5389 -- or protected object.
5397 then
5398 -- S is an enclosing task or protected object. The concurrent
5399 -- declaration has been converted into a type declaration, and
5400 -- the object itself has an object declaration that follows
5401 -- the type in the same declarative part.
5413 -- Call to current task. Will be transformed into call to Self
5420 New_N :=
5423 Selector_Name =>
5430 then
5431 -- Use the entry name (which must be unique at this point) to
5432 -- find the prefix that returns the corresponding task type or
5433 -- protected type.
5435 declare
5441 begin
5463 -- Up to this point the expression could have been the actual
5464 -- in a simple entry call, and be given by a named association.
5468 else
5474 ------------------------
5475 -- Resolve_Entry_Call --
5476 ------------------------
5488 begin
5489 -- We kill all checks here, because it does not seem worth the
5490 -- effort to do anything better, an entry call is a big operation.
5492 Kill_All_Checks;
5494 -- Processing of the name is similar for entry calls and protected
5495 -- operation calls. Once the entity is determined, we can complete
5496 -- the resolution of the actuals.
5498 -- The selector may be overloaded, in the case of a protected object
5499 -- with overloaded functions. The type of the context is used for
5500 -- resolution.
5505 then
5506 declare
5510 begin
5529 -- Simple entry call
5537 -- Call to member of entry family
5544 -- We cannot in general check the maximum depth of protected entry
5545 -- calls at compile time. But we can tell that any protected entry
5546 -- call at all violates a specified nesting depth of zero.
5552 -- Use context type to disambiguate a protected function that can be
5553 -- called without actuals and that returns an array type, and where
5554 -- the argument list may be an indexing of the returned value.
5559 and then
5567 then
5568 declare
5571 begin
5572 Index_Node :=
5574 Prefix =>
5579 -- Since we are correcting a node classification error made by
5580 -- the parser, we call Replace rather than Rewrite.
5590 -- The operation name may have been overloaded. Order the actuals
5591 -- according to the formals of the resolved entity, and set the
5592 -- return type to that of the operation.
5605 then
5609 -- Verify that a procedure call cannot masquerade as an entry
5610 -- call where an entry call is expected.
5615 then
5620 then
5625 then
5630 -- After resolution, entry calls and protected procedure calls
5631 -- are changed into entry calls, for expansion. The structure
5632 -- of the node does not change, so it can safely be done in place.
5633 -- Protected function calls must keep their structure because they
5634 -- are subexpressions.
5638 -- A protected operation that is not a function may modify the
5639 -- corresponding object, and cannot apply to a constant.
5640 -- If this is an internal call, the prefix is the type itself.
5646 then
5647 Error_Msg_N
5649 Entry_Name);
5663 -- Protected functions can return on the secondary stack, in which
5664 -- case we must trigger the transient scope mechanism.
5666 elsif Expander_Active
5668 then
5673 -------------------------
5674 -- Resolve_Equality_Op --
5675 -------------------------
5677 -- Both arguments must have the same type, and the boolean context
5678 -- does not participate in the resolution. The first pass verifies
5679 -- that the interpretation is not ambiguous, and the type of the left
5680 -- argument is correctly set, or is Any_Type in case of ambiguity.
5681 -- If both arguments are strings or aggregates, allocators, or Null,
5682 -- they are ambiguous even though they carry a single (universal) type.
5683 -- Diagnose this case here.
5691 -- In the case of allocators, make a last-ditch attempt to find a single
5692 -- access type with the right designated type. This is semantically
5693 -- dubious, and of no interest to any real code, but c48008a makes it
5694 -- all worthwhile.
5696 -----------------------------
5697 -- Find_Unique_Access_Type --
5698 -----------------------------
5705 begin
5710 else
5722 then
5735 -- Start of processing for Resolve_Equality_Op
5737 begin
5749 then
5752 else
5762 then
5775 -- If the unique type is a class-wide type then it will be expanded
5776 -- into a dispatching call to the predefined primitive. Therefore we
5777 -- check here for potential violation of such restriction.
5783 if Warn_On_Redundant_Constructs
5788 then
5796 -- If this is an inequality, it may be the implicit inequality
5797 -- created for a user-defined operation, in which case the corres-
5798 -- ponding equality operation is not intrinsic, and the operation
5799 -- cannot be constant-folded. Else fold.
5804 or else Is_Intrinsic_Subprogram
5806 then
5810 then
5814 -- Ada 2005: If one operand is an anonymous access type, convert
5815 -- the other operand to it, to ensure that the underlying types
5816 -- match in the back-end. Same for access_to_subprogram, and the
5817 -- conversion verifies that the types are subtype conformant.
5819 -- We apply the same conversion in the case one of the operands is
5820 -- a private subtype of the type of the other.
5822 -- Why the Expander_Active test here ???
5824 if Expander_Active
5825 and then
5829 then
5849 ----------------------------------
5850 -- Resolve_Explicit_Dereference --
5851 ----------------------------------
5860 begin
5865 -- Use the context type to select the prefix that has the correct
5866 -- designated type.
5877 else
5878 -- If no interpretation covers the designated type of the prefix,
5879 -- this is the pathological case where not all implementations of
5880 -- the prefix allow the interpretation of the node as a call. Now
5881 -- that the expected type is known, Remove other interpretations
5882 -- from prefix, rewrite it as a call, and resolve again, so that
5883 -- the proper call node is generated.
5894 New_N :=
5896 Name =>
5909 else
5917 -- If the designated type is a packed unconstrained array type, and the
5918 -- explicit dereference is not in the context of an attribute reference,
5919 -- then we must compute and set the actual subtype, since it is needed
5920 -- by Gigi. The reason we exclude the attribute case is that this is
5921 -- handled fine by Gigi, and in fact we use such attributes to build the
5922 -- actual subtype. We also exclude generated code (which builds actual
5923 -- subtypes directly if they are needed).
5930 then
5934 -- Note: there is no Eval processing required for an explicit deference,
5935 -- because the type is known to be an allocators, and allocator
5936 -- expressions can never be static.
5940 -------------------------------
5941 -- Resolve_Indexed_Component --
5942 -------------------------------
5950 begin
5953 -- Use the context type to select the prefix that yields the correct
5954 -- component type.
5956 declare
5963 begin
5970 and then Covers
5972 then
5981 else
5987 else
5998 else
6005 -- If prefix is access type, dereference to get real array type.
6006 -- Note: we do not apply an access check because the expander always
6007 -- introduces an explicit dereference, and the check will happen there.
6013 -- If name was overloaded, set component type correctly now
6014 -- If a misplaced call to an entry family (which has no index typs)
6015 -- return. Error will be diagnosed from calling context.
6019 else
6026 -- The prefix may have resolved to a string literal, in which case its
6027 -- etype has a special representation. This is only possible currently
6028 -- if the prefix is a static concatenation, written in functional
6029 -- notation.
6034 else
6041 else
6050 -- Do not generate the warning on suspicious index if we are analyzing
6051 -- package Ada.Tags; otherwise we will report the warning with the
6052 -- Prims_Ptr field of the dispatch table.
6055 or else not
6057 Ada_Tags)
6058 then
6064 -----------------------------
6065 -- Resolve_Integer_Literal --
6066 -----------------------------
6069 begin
6074 --------------------------------
6075 -- Resolve_Intrinsic_Operator --
6076 --------------------------------
6084 begin
6094 -- If the operand type is private, rewrite with suitable conversions on
6095 -- the operands and the result, to expose the proper underlying numeric
6096 -- type.
6103 else
6119 then
6120 -- Add explicit conversion where needed, and save interpretations
6121 -- in case operands are overloaded.
6128 else
6134 else
6144 else
6149 --------------------------------------
6150 -- Resolve_Intrinsic_Unary_Operator --
6151 --------------------------------------
6153 procedure Resolve_Intrinsic_Unary_Operator
6156 is
6161 begin
6180 else
6185 ------------------------
6186 -- Resolve_Logical_Op --
6187 ------------------------
6193 begin
6194 -- Predefined operations on scalar types yield the base type. On the
6195 -- other hand, logical operations on arrays yield the type of the
6196 -- arguments (and the context).
6200 else
6204 -- The following test is required because the operands of the operation
6205 -- may be literals, in which case the resulting type appears to be
6206 -- compatible with a signed integer type, when in fact it is compatible
6207 -- only with modular types. If the context itself is universal, the
6208 -- operation is illegal.
6216 Error_Msg_N
6223 then
6237 -- Check for violation of restriction No_Direct_Boolean_Operators
6238 -- if the operator was not eliminated by the Eval_Logical_Op call.
6242 then
6247 ---------------------------
6248 -- Resolve_Membership_Op --
6249 ---------------------------
6251 -- The context can only be a boolean type, and does not determine
6252 -- the arguments. Arguments should be unambiguous, but the preference
6253 -- rule for universal types applies.
6262 begin
6268 and then
6272 then
6275 -- Ada 2005 (AI-251): Give support to the following case:
6277 -- type I is interface;
6278 -- type T is tagged ...
6280 -- function Test (O : I'Class) is
6281 -- begin
6282 -- return O in T'Class.
6283 -- end Test;
6285 -- In this case we have nothing else to do; the membership test will be
6286 -- done at run-time.
6293 then
6296 else
6305 then
6311 else
6319 ------------------
6320 -- Resolve_Null --
6321 ------------------
6324 begin
6325 -- Handle restriction against anonymous null access values This
6326 -- restriction can be turned off using -gnatdh.
6328 -- Ada 2005 (AI-231): Remove restriction
6331 and then not Debug_Flag_J
6334 then
6335 -- In the common case of a call which uses an explicitly null
6336 -- value for an access parameter, give specialized error msg
6339 or else
6341 then
6342 Error_Msg_N
6345 -- Standard message for all other cases (are there any?)
6347 else
6348 Error_Msg_N
6353 -- In a distributed context, null for a remote access to subprogram
6354 -- may need to be replaced with a special record aggregate. In this
6355 -- case, return after having done the transformation.
6360 then
6364 -- The null literal takes its type from the context
6369 -----------------------
6370 -- Resolve_Op_Concat --
6371 -----------------------
6375 -- We wish to avoid deep recursion, because concatenations are often
6376 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
6377 -- operands nonrecursively until we find something that is not a simple
6378 -- concatenation (A in this case). We resolve that, and then walk back
6379 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
6380 -- to do the rest of the work at each level. The Parent pointers allow
6381 -- us to avoid recursion, and thus avoid running out of memory. See also
6382 -- Sem_Ch4.Analyze_Concatenation, where a similar hack is used.
6387 begin
6388 -- The following code is equivalent to:
6390 -- Resolve_Op_Concat_First (NN, Typ);
6391 -- Resolve_Op_Concat_Arg (N, ...);
6392 -- Resolve_Op_Concat_Rest (N, Typ);
6394 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
6395 -- operand is a concatenation.
6397 -- Walk down left operands
6399 loop
6408 -- Now (given the above example) NN is A&B and Op1 is A
6410 -- First resolve Op1 ...
6414 -- ... then walk NN back up until we reach N (where we started), calling
6415 -- Resolve_Op_Concat_Rest along the way.
6417 loop
6424 ---------------------------
6425 -- Resolve_Op_Concat_Arg --
6426 ---------------------------
6428 procedure Resolve_Op_Concat_Arg
6433 is
6436 begin
6438 if Is_Comp
6442 then
6444 else
6451 then
6454 else
6459 else
6463 then
6464 declare
6469 begin
6474 -- Special-case the error message when the overloading is
6475 -- caused by a function that yields an array and can be
6476 -- called without parameters.
6481 Error_Msg_NE
6483 Error_Msg_NE
6487 else
6488 Error_Msg_N
6497 then
6515 else
6520 else
6527 -----------------------------
6528 -- Resolve_Op_Concat_First --
6529 -----------------------------
6536 begin
6537 -- The parser folds an enormous sequence of concatenations of string
6538 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
6539 -- in the right. If the expression resolves to a predefined "&"
6540 -- operator, all is well. Otherwise, the parser's folding is wrong, so
6541 -- we give an error. See P_Simple_Expression in Par.Ch4.
6546 then
6561 ----------------------------
6562 -- Resolve_Op_Concat_Rest --
6563 ----------------------------
6569 begin
6578 -- If this is not a static concatenation, but the result is a
6579 -- string type (and not an array of strings) ensure that static
6580 -- string operands have their subtypes properly constructed.
6584 then
6590 ----------------------
6591 -- Resolve_Op_Expon --
6592 ----------------------
6597 begin
6598 -- Catch attempts to do fixed-point exponentation with universal
6599 -- operands, which is a case where the illegality is not caught during
6600 -- normal operator analysis.
6611 then
6618 then
6622 -- We do the resolution using the base type, because intermediate values
6623 -- in expressions always are of the base type, not a subtype of it.
6635 -- Set overflow checking bit. Much cleverer code needed here eventually
6636 -- and perhaps the Resolve routines should be separated for the various
6637 -- arithmetic operations, since they will need different processing. ???
6646 --------------------
6647 -- Resolve_Op_Not --
6648 --------------------
6654 -- This function determines if the parent node is a boolean operator
6655 -- or operation (comparison op, membership test, or short circuit form)
6656 -- and the not in question is the left operand of this operation.
6657 -- Note that if the not is in parens, then false is returned.
6659 -----------------------
6660 -- Parent_Is_Boolean --
6661 -----------------------
6664 begin
6668 else
6670 when N_Op_And |
6671 N_Op_Eq |
6672 N_Op_Ge |
6673 N_Op_Gt |
6674 N_Op_Le |
6675 N_Op_Lt |
6676 N_Op_Ne |
6677 N_Op_Or |
6678 N_Op_Xor |
6679 N_In |
6680 N_Not_In |
6681 N_And_Then |
6682 N_Or_Else =>
6692 -- Start of processing for Resolve_Op_Not
6694 begin
6695 -- Predefined operations on scalar types yield the base type. On the
6696 -- other hand, logical operations on arrays yield the type of the
6697 -- arguments (and the context).
6701 else
6705 -- Straigtforward case of incorrect arguments
6712 -- Special case of probable missing parens
6716 Error_Msg_N
6719 else
6720 Error_Msg_N
6727 -- OK resolution of not
6729 else
6730 -- Warn if non-boolean types involved. This is a case like not a < b
6731 -- where a and b are modular, where we will get (not a) < b and most
6732 -- likely not (a < b) was intended.
6734 if Warn_On_Questionable_Missing_Parens
6736 and then Parent_Is_Boolean
6737 then
6749 -----------------------------
6750 -- Resolve_Operator_Symbol --
6751 -----------------------------
6753 -- Nothing to be done, all resolved already
6759 begin
6763 ----------------------------------
6764 -- Resolve_Qualified_Expression --
6765 ----------------------------------
6773 begin
6776 -- A qualified expression requires an exact match of the type,
6777 -- class-wide matching is not allowed. However, if the qualifying
6778 -- type is specific and the expression has a class-wide type, it
6779 -- may still be okay, since it can be the result of the expansion
6780 -- of a call to a dispatching function, so we also have to check
6781 -- class-wideness of the type of the expression's original node.
6784 or else
6788 then
6792 -- If the target type is unconstrained, then we reset the type of
6793 -- the result from the type of the expression. For other cases, the
6794 -- actual subtype of the expression is the target type.
6798 then
6805 -------------------
6806 -- Resolve_Range --
6807 -------------------
6813 begin
6821 -- We have to check the bounds for being within the base range as
6822 -- required for a non-static context. Normally this is automatic and
6823 -- done as part of evaluating expressions, but the N_Range node is an
6824 -- exception, since in GNAT we consider this node to be a subexpression,
6825 -- even though in Ada it is not. The circuit in Sem_Eval could check for
6826 -- this, but that would put the test on the main evaluation path for
6827 -- expressions.
6832 -- Check for an ambiguous range over character literals. This will
6833 -- happen with a membership test involving only literals.
6841 -- If bounds are static, constant-fold them, so size computations
6842 -- are identical between front-end and back-end. Do not perform this
6843 -- transformation while analyzing generic units, as type information
6844 -- would then be lost when reanalyzing the constant node in the
6845 -- instance.
6858 --------------------------
6859 -- Resolve_Real_Literal --
6860 --------------------------
6865 begin
6866 -- Special processing for fixed-point literals to make sure that the
6867 -- value is an exact multiple of small where this is required. We
6868 -- skip this for the universal real case, and also for generic types.
6874 then
6875 declare
6882 begin
6883 -- Case of literal is not an exact multiple of the Small
6887 -- For a source program literal for a decimal fixed-point
6888 -- type, this is statically illegal (RM 4.9(36)).
6893 then
6897 -- Generate a warning if literal from source
6900 and then Warn_On_Bad_Fixed_Value
6901 then
6902 Error_Msg_N
6904 N);
6907 -- Replace literal by a value that is the exact representation
6908 -- of a value of the type, i.e. a multiple of the small value,
6909 -- by truncation, since Machine_Rounds is false for all GNAT
6910 -- fixed-point types (RM 4.9(38)).
6920 -- In all cases, set the corresponding integer field
6926 -- Now replace the actual type by the expected type as usual
6932 -----------------------
6933 -- Resolve_Reference --
6934 -----------------------
6939 begin
6940 -- Replace general access with specific type
6948 -- If we are taking the reference of a volatile entity, then treat
6949 -- it as a potential modification of this entity. This is much too
6950 -- conservative, but is necessary because remove side effects can
6951 -- result in transformations of normal assignments into reference
6952 -- sequences that otherwise fail to notice the modification.
6959 --------------------------------
6960 -- Resolve_Selected_Component --
6961 --------------------------------
6976 -- Check whether this is the initialization of a component within an
6977 -- init proc (by assignment or call to another init proc). If true,
6978 -- there is no need for a discriminant check.
6980 --------------------
6981 -- Init_Component --
6982 --------------------
6985 begin
6986 return Inside_Init_Proc
6992 -- Start of processing for Resolve_Selected_Component
6994 begin
6997 -- Use the context type to select the prefix that has a selector
6998 -- of the correct name and type.
7006 else
7012 -- The visible components of a class-wide type are those of
7013 -- the root type.
7023 then
7030 else
7034 Error_Msg_N
7039 else
7042 -- There may be an implicit dereference. Retrieve
7043 -- designated record type.
7047 else
7053 -- Resolution chooses the new interpretation.
7054 -- Find the component with the right name.
7059 loop
7081 else
7082 -- Resolve prefix with its type
7087 -- Generate cross-reference. We needed to wait until full overloading
7088 -- resolution was complete to do this, since otherwise we can't tell if
7089 -- we are an Lvalue of not.
7093 else
7097 -- If prefix is an access type, the node will be transformed into an
7098 -- explicit dereference during expansion. The type of the node is the
7099 -- designated type of that of the prefix.
7104 else
7110 or else
7117 and then not Init_Component
7118 then
7126 -- If the prefix is a record conversion, this may be a renamed
7127 -- discriminant whose bounds differ from those of the original
7128 -- one, so we must ensure that a range check is performed.
7133 then
7137 -- Note: No Eval processing is required, because the prefix is of a
7138 -- record type, or protected type, and neither can possibly be static.
7142 -------------------
7143 -- Resolve_Shift --
7144 -------------------
7151 begin
7152 -- We do the resolution using the base type, because intermediate values
7153 -- in expressions always are of the base type, not a subtype of it.
7166 ---------------------------
7167 -- Resolve_Short_Circuit --
7168 ---------------------------
7175 begin
7179 -- Check for issuing warning for always False assert, this happens
7180 -- when assertions are turned off, in which case the pragma Assert
7181 -- was transformed into:
7183 -- if False and then <condition> then ...
7185 -- and we detect this pattern
7187 if Warn_On_Assertion_Failure
7194 then
7195 declare
7197 begin
7200 then
7201 -- Don't want to warn if original condition is explicit False
7203 declare
7205 Original_Node
7206 (Expression
7208 begin
7211 then
7213 else
7214 -- Issue warning. Note that we don't want to make this
7215 -- an unconditional warning, because if the assert is
7216 -- within deleted code we do not want the warning. But
7217 -- we do not want the deletion of the IF/AND-THEN to
7218 -- take this message with it. We achieve this by making
7219 -- sure that the expanded code points to the Sloc of
7220 -- the expression, not the original pragma.
7229 -- Continue with processing of short circuit
7238 -------------------
7239 -- Resolve_Slice --
7240 -------------------
7248 begin
7251 -- Use the context type to select the prefix that yields the
7252 -- correct array type.
7254 declare
7261 begin
7269 then
7277 else
7282 else
7293 else
7303 -- If the prefix is an access to an unconstrained array, we must use
7304 -- the actual subtype of the object to perform the index checks. The
7305 -- object denoted by the prefix is implicit in the node, so we build
7306 -- an explicit representation for it in order to compute the actual
7307 -- subtype.
7312 declare
7316 begin
7326 then
7329 -- If the name is a selected component that depends on discriminants,
7330 -- build an actual subtype for it. This can happen only when the name
7331 -- itself is overloaded; otherwise the actual subtype is created when
7332 -- the selected component is analyzed.
7335 and then Full_Analysis
7337 then
7338 declare
7341 begin
7347 -- If name was overloaded, set slice type correctly now
7351 -- If the range is specified by a subtype mark, no resolution is
7352 -- necessary. Else resolve the bounds, and apply needed checks.
7360 -- Do not apply the range check to nodes associated with the
7361 -- frontend expansion of the dispatch table. We first check
7362 -- if Ada.Tags is already loaded to void the addition of an
7363 -- undesired dependence on such run-time unit.
7365 and then
7367 or else not
7373 then
7388 ----------------------------
7389 -- Resolve_String_Literal --
7390 ----------------------------
7401 begin
7402 -- For a string appearing in a concatenation, defer creation of the
7403 -- string_literal_subtype until the end of the resolution of the
7404 -- concatenation, because the literal may be constant-folded away. This
7405 -- is a useful optimization for long concatenation expressions.
7407 -- If the string is an aggregate built for a single character (which
7408 -- happens in a non-static context) or a is null string to which special
7409 -- checks may apply, we build the subtype. Wide strings must also get a
7410 -- string subtype if they come from a one character aggregate. Strings
7411 -- generated by attributes might be static, but it is often hard to
7412 -- determine whether the enclosing context is static, so we generate
7413 -- subtypes for them as well, thus losing some rarer optimizations ???
7414 -- Same for strings that come from a static conversion.
7416 Need_Check :=
7425 -- If the resolving type is itself a string literal subtype, we
7426 -- can just reuse it, since there is no point in creating another.
7432 and then not Need_Check
7437 then
7440 -- Otherwise we must create a string literal subtype. Note that the
7441 -- whole idea of string literal subtypes is simply to avoid the need
7442 -- for building a full fledged array subtype for each literal.
7443 else
7449 or else Need_Check
7450 then
7457 then
7463 -- The validity of a null string has been checked in the
7464 -- call to Eval_String_Literal.
7469 -- Always accept string literal with component type Any_Character, which
7470 -- occurs in error situations and in comparisons of literals, both of
7471 -- which should accept all literals.
7476 -- If the type is bit-packed, then we always tranform the string literal
7477 -- into a full fledged aggregate.
7482 -- Deal with cases of Wide_Wide_String, Wide_String, and String
7484 else
7485 -- For Standard.Wide_Wide_String, or any other type whose component
7486 -- type is Standard.Wide_Wide_Character, we know that all the
7487 -- characters in the string must be acceptable, since the parser
7488 -- accepted the characters as valid character literals.
7493 -- For the case of Standard.String, or any other type whose component
7494 -- type is Standard.Character, we must make sure that there are no
7495 -- wide characters in the string, i.e. that it is entirely composed
7496 -- of characters in range of type Character.
7498 -- If the string literal is the result of a static concatenation, the
7499 -- test has already been performed on the components, and need not be
7500 -- repeated.
7504 then
7508 -- If we are out of range, post error. This is one of the
7509 -- very few places that we place the flag in the middle of
7510 -- a token, right under the offending wide character.
7512 Error_Msg
7519 -- For the case of Standard.Wide_String, or any other type whose
7520 -- component type is Standard.Wide_Character, we must make sure that
7521 -- there are no wide characters in the string, i.e. that it is
7522 -- entirely composed of characters in range of type Wide_Character.
7524 -- If the string literal is the result of a static concatenation,
7525 -- the test has already been performed on the components, and need
7526 -- not be repeated.
7530 then
7534 -- If we are out of range, post error. This is one of the
7535 -- very few places that we place the flag in the middle of
7536 -- a token, right under the offending wide character.
7538 -- This is not quite right, because characters in general
7539 -- will take more than one character position ???
7541 Error_Msg
7548 -- If the root type is not a standard character, then we will convert
7549 -- the string into an aggregate and will let the aggregate code do
7550 -- the checking. Standard Wide_Wide_Character is also OK here.
7552 else
7556 -- See if the component type of the array corresponding to the string
7557 -- has compile time known bounds. If yes we can directly check
7558 -- whether the evaluation of the string will raise constraint error.
7559 -- Otherwise we need to transform the string literal into the
7560 -- corresponding character aggregate and let the aggregate
7561 -- code do the checking.
7566 then
7567 -- Check for the case of full range, where we are definitely OK
7573 -- Here the range is not the complete base type range, so check
7575 declare
7583 begin
7586 then
7592 then
7593 Apply_Compile_Time_Constraint_Error
7605 -- If we got here we meed to transform the string literal into the
7606 -- equivalent qualified positional array aggregate. This is rather
7607 -- heavy artillery for this situation, but it is hard work to avoid.
7609 declare
7614 begin
7615 -- Build the character literals, we give them source locations that
7616 -- correspond to the string positions, which is a bit tricky given
7617 -- the possible presence of wide character escape sequences.
7631 -- Should we have a call to Skip_Wide here ???
7632 -- ??? else
7633 -- Skip_Wide (P);
7641 Expression =>
7648 -----------------------------
7649 -- Resolve_Subprogram_Info --
7650 -----------------------------
7653 begin
7657 -----------------------------
7658 -- Resolve_Type_Conversion --
7659 -----------------------------
7670 begin
7671 if not Conv_OK
7673 then
7679 -- Mixed-mode operation involving a literal. Context must be a fixed
7680 -- type which is applied to the literal subsequently.
7690 then
7691 -- Return if expression is ambiguous
7696 -- If nothing else, the available fixed type is Duration
7698 else
7702 -- Resolve the real operand with largest available precision
7706 else
7712 -- If the operand is a literal (it could be a non-static and
7713 -- illegal exponentiation) check whether the use of Duration
7714 -- is potentially inaccurate.
7719 then
7720 Error_Msg_N
7723 Rop);
7724 Error_Msg_N
7731 then
7734 else
7743 -- Note: we do the Eval_Type_Conversion call before applying the
7744 -- required checks for a subtype conversion. This is important,
7745 -- since both are prepared under certain circumstances to change
7746 -- the type conversion to a constraint error node, but in the case
7747 -- of Eval_Type_Conversion this may reflect an illegality in the
7748 -- static case, and we would miss the illegality (getting only a
7749 -- warning message), if we applied the type conversion checks first.
7753 -- Even when evaluation is not possible, we may be able to simplify
7754 -- the conversion or its expression. This needs to be done before
7755 -- applying checks, since otherwise the checks may use the original
7756 -- expression and defeat the simplifications. This is specifically
7757 -- the case for elimination of the floating-point Truncation
7758 -- attribute in float-to-int conversions.
7762 -- If after evaluation we still have a type conversion, then we
7763 -- may need to apply checks required for a subtype conversion.
7765 -- Skip these type conversion checks if universal fixed operands
7766 -- operands involved, since range checks are handled separately for
7767 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
7773 then
7777 -- Issue warning for conversion of simple object to its own type
7778 -- We have to test the original nodes, since they may have been
7779 -- rewritten by various optimizations.
7783 if Warn_On_Redundant_Constructs
7786 and then not In_Instance
7787 then
7791 -- If the node is part of a larger expression, the Target_Type
7792 -- may not be the original type of the node if the context is a
7793 -- condition. Recover original type to see if conversion is needed.
7797 then
7802 and then
7804 or else
7807 then
7809 Error_Msg_NE
7814 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
7815 -- No need to perform any interface conversion if the type of the
7816 -- expression coincides with the target type.
7819 and then Expander_Active
7821 then
7822 declare
7826 begin
7838 -- Conversion from interface type
7842 -- Ada 2005 (AI-217): Handle entities from limited views
7848 Error_Msg_N
7850 N);
7853 and then not
7856 then
7860 Error_Msg_N
7862 N);
7864 else
7868 -- Conversion to interface type
7872 -- Handle subtypes
7876 then
7880 if not Interface_Present_In_Ancestor
7883 then
7886 -- The static analysis is not enough to know if the
7887 -- interface is implemented or not. Hence we must pass
7888 -- the work to the expander to generate code to evaluate
7889 -- the conversion at run-time.
7893 else
7896 Error_Msg_N
7901 else
7909 ----------------------
7910 -- Resolve_Unary_Op --
7911 ----------------------
7920 begin
7921 -- Deal with intrinsic unary operators
7927 then
7932 -- Deal with universal cases
7935 or else
7937 then
7944 -- Generate warning for expressions like abs (x mod 2)
7946 if Warn_On_Redundant_Constructs
7948 then
7952 Error_Msg_N
7957 -- Deal with reference generation
7963 -- Set overflow checking bit. Much cleverer code needed here eventually
7964 -- and perhaps the Resolve routines should be separated for the various
7965 -- arithmetic operations, since they will need different processing ???
7973 -- Generate warning for expressions like -5 mod 3 for integers. No
7974 -- need to worry in the floating-point case, since parens do not affect
7975 -- the result so there is no point in giving in a warning.
7977 declare
7986 begin
7987 if Warn_On_Questionable_Missing_Parens
7991 then
7994 -- We are looking for cases where the right operand is not
7995 -- parenthesized, and is a bianry operator, multiply, divide, or
7996 -- mod. These are the cases where the grouping can affect results.
8000 or else
8002 or else
8004 then
8005 -- For mod, we always give the warning, since the value is
8006 -- affected by the parenthesization (e.g. (-5) mod 315 /=
8007 -- (5 mod 315)). But for the other cases, the only concern is
8008 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
8009 -- overflows, but (-2) * 64 does not). So we try to give the
8010 -- message only when overflow is possible.
8014 then
8019 else
8025 else
8029 -- Note that the test below is deliberately excluding
8030 -- the largest negative number, since that is a potentially
8031 -- troublesome case (e.g. -2 * x, where the result is the
8032 -- largest negative integer has an overflow with 2 * x).
8039 -- For the multiplication case, the only case we have to worry
8040 -- about is when (-a)*b is exactly the largest negative number
8041 -- so that -(a*b) can cause overflow. This can only happen if
8042 -- a is a power of 2, and more generally if any operand is a
8043 -- constant that is not a power of 2, then the parentheses
8044 -- cannot affect whether overflow occurs. We only bother to
8045 -- test the left most operand
8047 -- Loop looking at left operands for one that has known value
8054 -- Operand value of 0 or 1 skips warning
8059 -- Otherwise check power of 2, if power of 2, warn, if
8060 -- anything else, skip warning.
8062 else
8066 else
8075 -- Keep looking at left operands
8080 -- For rem or "/" we can only have a problematic situation
8081 -- if the divisor has a value of minus one or one. Otherwise
8082 -- overflow is impossible (divisor > 1) or we have a case of
8083 -- division by zero in any case.
8086 or else
8090 then
8094 -- If we fall through warning should be issued
8096 Error_Msg_N
8103 ----------------------------------
8104 -- Resolve_Unchecked_Expression --
8105 ----------------------------------
8107 procedure Resolve_Unchecked_Expression
8110 is
8111 begin
8116 ---------------------------------------
8117 -- Resolve_Unchecked_Type_Conversion --
8118 ---------------------------------------
8120 procedure Resolve_Unchecked_Type_Conversion
8123 is
8129 begin
8130 -- Resolve operand using its own type
8137 ------------------------------
8138 -- Rewrite_Operator_As_Call --
8139 ------------------------------
8146 begin
8153 New_N :=
8164 ------------------------------
8165 -- Rewrite_Renamed_Operator --
8166 ------------------------------
8168 procedure Rewrite_Renamed_Operator
8172 is
8177 begin
8178 -- Rewrite the operator node using the real operator, not its
8179 -- renaming. Exclude user-defined intrinsic operations of the same
8180 -- name, which are treated separately and rewritten as calls.
8184 then
8191 -- Indicate that both the original entity and its renaming are
8192 -- referenced at this point.
8203 -- If the context type is private, add the appropriate conversions
8204 -- so that the operator is applied to the full view. This is done
8205 -- in the routines that resolve intrinsic operators,
8209 then
8211 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
8212 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
8225 then
8226 -- Operator renames a user-defined operator of the same name. Use
8227 -- the original operator in the node, which is the one that Gigi
8228 -- knows about.
8235 -----------------------
8236 -- Set_Slice_Subtype --
8237 -----------------------
8239 -- Build an implicit subtype declaration to represent the type delivered
8240 -- by the slice. This is an abbreviated version of an array subtype. We
8241 -- define an index subtype for the slice, using either the subtype name
8242 -- or the discrete range of the slice. To be consistent with index usage
8243 -- elsewhere, we create a list header to hold the single index. This list
8244 -- is not otherwise attached to the syntax tree.
8255 begin
8259 else
8260 -- We force the evaluation of a range. This is definitely needed in
8261 -- the renamed case, and seems safer to do unconditionally. Note in
8262 -- any case that since we will create and insert an Itype referring
8263 -- to this range, we must make sure any side effect removal actions
8264 -- are inserted before the Itype definition.
8294 -- The Etype of the existing Slice node is reset to this slice subtype.
8295 -- Its bounds are obtained from its first index.
8299 -- In the packed case, this must be immediately frozen
8301 -- Couldn't we always freeze here??? and if we did, then the above
8302 -- call to Check_Compile_Time_Size could be eliminated, which would
8303 -- be nice, because then that routine could be made private to Freeze.
8311 --------------------------------
8312 -- Set_String_Literal_Subtype --
8313 --------------------------------
8321 begin
8335 -- The low bound is set from the low bound of the corresponding
8336 -- index type. Note that we do not store the high bound in the
8337 -- string literal subtype, but it can be deduced if necessary
8338 -- from the length and the low bound.
8342 else
8343 Set_String_Literal_Low_Bound
8347 -- Build bona fide subtype for the string, and wrap it in an
8348 -- unchecked conversion, because the backend expects the
8349 -- String_Literal_Subtype to have a static lower bound.
8351 declare
8357 Right_Opnd =>
8365 begin
8366 Index_Subtype :=
8373 -- In the context, the Index_Type may already have a constraint,
8374 -- so use common base type on string subtype. The base type may
8375 -- be used when generating attributes of the string, for example
8376 -- in the context of a slice assignment.
8402 ------------------------------
8403 -- Simplify_Type_Conversion --
8404 ------------------------------
8407 begin
8409 declare
8414 begin
8416 and then
8423 -- Special processing required if the conversion is the expression
8424 -- of a Truncation attribute reference. In this case we replace:
8426 -- ityp (ftyp'Truncation (x))
8428 -- by
8430 -- ityp (x)
8432 -- with the Float_Truncate flag set, which is more efficient
8434 then
8443 -----------------------------
8444 -- Unique_Fixed_Point_Type --
8445 -----------------------------
8454 -- If true ambiguity, give details
8456 -----------------------
8457 -- Fixed_Point_Error --
8458 -----------------------
8461 begin
8467 -- Start of processing for Unique_Fixed_Point_Type
8469 begin
8470 -- The operations on Duration are visible, so Duration is always a
8471 -- possible interpretation.
8475 -- Look for fixed-point types in enclosing scopes
8484 then
8486 Fixed_Point_Error;
8488 else
8499 -- Look for visible fixed type declarations in the context
8511 then
8513 Fixed_Point_Error;
8515 else
8530 else
8537 ----------------------
8538 -- Valid_Conversion --
8539 ----------------------
8541 function Valid_Conversion
8545 is
8549 function Conversion_Check
8552 -- Little routine to post Msg if Valid is False, returns Valid value
8554 function Valid_Tagged_Conversion
8557 -- Specifically test for validity of tagged conversions
8560 -- Check index and component conformance, and accessibility levels
8561 -- if the component types are anonymous access types (Ada 2005)
8563 ----------------------
8564 -- Conversion_Check --
8565 ----------------------
8567 function Conversion_Check
8570 is
8571 begin
8579 ----------------------------
8580 -- Valid_Array_Conversion --
8581 ----------------------------
8584 is
8599 begin
8600 -- Error if wrong number of dimensions
8602 if
8604 then
8605 Error_Msg_N
8609 -- Number of dimensions matches
8611 else
8612 -- Loop through indexes of the two arrays
8620 -- Error if index types are incompatible
8626 then
8627 Error_Msg_N
8629 Operand);
8637 -- If component types have same base type, all set
8642 -- Here if base types of components are not the same. The only
8643 -- time this is allowed is if we have anonymous access types.
8645 -- The conversion of arrays of anonymous access types can lead
8646 -- to dangling pointers. AI-392 formalizes the accessibility
8647 -- checks that must be applied to such conversions to prevent
8648 -- out-of-scope references.
8650 elsif
8652 or else
8655 and then
8657 then
8660 then
8665 Operand);
8672 -- Conversion not allowed because of accessibility levels
8674 else
8679 else
8683 -- All other cases where component base types do not match
8685 else
8686 Error_Msg_N
8688 Operand);
8692 -- Check that component subtypes statically match
8696 or else not Subtypes_Statically_Match
8698 then
8699 Error_Msg_N
8708 -----------------------------
8709 -- Valid_Tagged_Conversion --
8710 -----------------------------
8712 function Valid_Tagged_Conversion
8715 is
8716 begin
8717 -- Upward conversions are allowed (RM 4.6(22))
8721 then
8724 -- Downward conversion are allowed if the operand is class-wide
8725 -- (RM 4.6(23)).
8729 then
8734 then
8735 return
8739 -- Ada 2005 (AI-251): The conversion to/from interface types is
8740 -- always valid
8745 -- If the operand is a class-wide type obtained through a limited_
8746 -- with clause, and the context includes the non-limited view, use
8747 -- it to determine whether the conversion is legal.
8753 then
8758 then
8761 else
8762 Error_Msg_NE
8769 -- Start of processing for Valid_Conversion
8771 begin
8775 declare
8782 begin
8783 -- Remove procedure calls, which syntactically cannot appear
8784 -- in this context, but which cannot be removed by type checking,
8785 -- because the context does not impose a type.
8787 -- When compiling for VMS, spurious ambiguities can be produced
8788 -- when arithmetic operations have a literal operand and return
8789 -- System.Address or a descendant of it. These ambiguities are
8790 -- otherwise resolved by the context, but for conversions there
8791 -- is no context type and the removal of the spurious operations
8792 -- must be done explicitly here.
8794 -- The node may be labelled overloaded, but still contain only
8795 -- one interpretation because others were discarded in previous
8796 -- filters. If this is the case, retain the single interpretation
8797 -- if legal.
8805 then
8806 -- More than one candidate interpretation is available
8816 then
8857 -- Numeric types
8861 -- A universal fixed expression can be converted to any numeric type
8866 -- Also no need to check when in an instance or inlined body, because
8867 -- the legality has been established when the template was analyzed.
8868 -- Furthermore, numeric conversions may occur where only a private
8869 -- view of the operand type is visible at the instanciation point.
8870 -- This results in a spurious error if we check that the operand type
8871 -- is a numeric type.
8873 -- Note: in a previous version of this unit, the following tests were
8874 -- applied only for generated code (Comes_From_Source set to False),
8875 -- but in fact the test is required for source code as well, since
8876 -- this situation can arise in source code.
8881 -- Otherwise we need the conversion check
8883 else
8884 return Conversion_Check
8889 -- Array types
8895 then
8896 Error_Msg_N
8899 else
8903 -- Ada 2005 (AI-251): Anonymous access types where target references an
8904 -- interface type.
8907 or else
8910 then
8911 -- Check the static accessibility rule of 4.6(17). Note that the
8912 -- check is not enforced when within an instance body, since the RM
8913 -- requires such cases to be caught at run time.
8918 then
8919 -- In an instance, this is a run-time check, but one we know
8920 -- will fail, so generate an appropriate warning. The raise
8921 -- will be generated by Expand_N_Type_Conversion.
8924 Error_Msg_N
8926 Operand);
8927 Error_Msg_N
8929 else
8930 Error_Msg_N
8932 Operand);
8936 -- Special accessibility checks are needed in the case of access
8937 -- discriminants declared for a limited type.
8941 then
8942 -- When the operand is a selected access discriminant the check
8943 -- needs to be made against the level of the object denoted by
8944 -- the prefix of the selected name. (Object_Access_Level
8945 -- handles checking the prefix of the operand for this case.)
8950 then
8951 -- In an instance, this is a run-time check, but one we
8952 -- know will fail, so generate an appropriate warning.
8953 -- The raise will be generated by Expand_N_Type_Conversion.
8956 Error_Msg_N
8959 Error_Msg_N
8961 else
8962 Error_Msg_N
8969 -- The case of a reference to an access discriminant from
8970 -- within a limited type declaration (which will appear as
8971 -- a discriminal) is always illegal because the level of the
8972 -- discriminant is considered to be deeper than any (namable)
8973 -- access type.
8980 then
8981 Error_Msg_N
8983 Operand);
8991 -- General and anonymous access types
8995 and then
8996 Conversion_Check
8999 E_Access_Subprogram_Type
9001 E_Access_Protected_Subprogram_Type,
9003 then
9006 then
9007 Error_Msg_N
9012 -- Check the static accessibility rule of 4.6(17). Note that the
9013 -- check is not enforced when within an instance body, since the RM
9014 -- requires such cases to be caught at run time.
9018 then
9021 then
9022 -- In an instance, this is a run-time check, but one we
9023 -- know will fail, so generate an appropriate warning.
9024 -- The raise will be generated by Expand_N_Type_Conversion.
9027 Error_Msg_N
9029 Operand);
9030 Error_Msg_N
9033 else
9034 -- Avoid generation of spurious error message
9037 Error_Msg_N
9039 Operand);
9045 -- Special accessibility checks are needed in the case of access
9046 -- discriminants declared for a limited type.
9050 then
9052 -- When the operand is a selected access discriminant the check
9053 -- needs to be made against the level of the object denoted by
9054 -- the prefix of the selected name. (Object_Access_Level
9055 -- handles checking the prefix of the operand for this case.)
9060 then
9061 -- In an instance, this is a run-time check, but one we
9062 -- know will fail, so generate an appropriate warning.
9063 -- The raise will be generated by Expand_N_Type_Conversion.
9066 Error_Msg_N
9069 Error_Msg_N
9071 Operand);
9073 else
9074 Error_Msg_N
9081 -- The case of a reference to an access discriminant from
9082 -- within a limited type declaration (which will appear as
9083 -- a discriminal) is always illegal because the level of the
9084 -- discriminant is considered to be deeper than any (namable)
9085 -- access type.
9091 then
9092 Error_Msg_N
9094 Operand);
9100 declare
9102 -- Helper function to handle limited views
9104 --------------------------
9105 -- Full_Designated_Type --
9106 --------------------------
9110 begin
9114 then
9116 else
9127 begin
9131 else
9133 Error_Msg_NE
9138 -- Ada 2005 AI-384: legality rule is symmetric in both
9139 -- designated types. The conversion is legal (with possible
9140 -- constraint check) if either designated type is
9141 -- unconstrained.
9144 or else
9146 and then
9149 then
9152 else
9153 Error_Msg_NE
9161 -- Subprogram access types
9164 or else
9167 then
9168 if
9170 then
9171 Error_Msg_N
9173 Operand);
9174 Error_Msg_N
9177 Operand);
9181 then
9182 Error_Msg_NE
9188 -- Check that the designated types are subtype conformant
9194 -- Check the static accessibility rule of 4.6(20)
9198 then
9199 Error_Msg_N
9201 Operand);
9203 -- Check that if the operand type is declared in a generic body,
9204 -- then the target type must be declared within that same body
9205 -- (enforces last sentence of 4.6(20)).
9208 declare
9214 begin
9221 Error_Msg_N
9230 -- Remote subprogram access types
9234 then
9235 -- It is valid to convert from one RAS type to another provided
9236 -- that their specification statically match.
9238 Check_Subtype_Conformant
9241 Old_Id =>
9243 Err_Loc =>
9244 N);
9247 -- If both are tagged types, check legality of view conversions
9251 then
9254 -- Types derived from the same root type are convertible
9259 -- In an instance or an inlined body, there may be inconsistent
9260 -- views of the same type, or of types derived from a common root.
9263 and then
9266 then
9269 -- Special check for common access type error case
9273 then
9279 else