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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 -- Utility to check whether the name in the call is a predefined
121 -- operator, in which case the call is made into an operator node.
122 -- An instance of an intrinsic conversion operation may be given
123 -- an operator name, but is not treated like an operator.
126 -- If a default expression in entry call N depends on the discriminants
127 -- of the task, it must be replaced with a reference to the discriminant
128 -- of the task being called.
163 function Operator_Kind
166 -- Utility to map the name of an operator into the corresponding Node. Used
167 -- by other node rewriting procedures.
170 -- Resolve actuals of call, and add default expressions for missing ones.
171 -- N is the Node_Id for the subprogram call, and Nam is the entity of the
172 -- called subprogram.
175 -- Called from Resolve_Call, when the prefix denotes an entry or element
176 -- of entry family. Actuals are resolved as for subprograms, and the node
177 -- is rebuilt as an entry call. Also called for protected operations. Typ
178 -- is the context type, which is used when the operation is a protected
179 -- function with no arguments, and the return value is indexed.
182 -- A call to a user-defined intrinsic operator is rewritten as a call
183 -- to the corresponding predefined operator, with suitable conversions.
186 -- Ditto, for unary operators (only arithmetic ones)
189 -- If an operator node resolves to a call to a user-defined operator,
190 -- rewrite the node as a function call.
192 procedure Make_Call_Into_Operator
196 -- Inverse transformation: if an operator is given in functional notation,
197 -- then after resolving the node, transform into an operator node, so
198 -- that operands are resolved properly. Recall that predefined operators
199 -- do not have a full signature and special resolution rules apply.
201 procedure Rewrite_Renamed_Operator
205 -- An operator can rename another, e.g. in an instantiation. In that
206 -- case, the proper operator node must be constructed and resolved.
209 -- The String_Literal_Subtype is built for all strings that are not
210 -- operands of a static concatenation operation. If the argument is
211 -- not a N_String_Literal node, then the call has no effect.
214 -- Build subtype of array type, with the range specified by the slice
217 -- Called after N has been resolved and evaluated, but before range checks
218 -- have been applied. Currently simplifies a combination of floating-point
219 -- to integer conversion and Truncation attribute.
222 -- A universal_fixed expression in an universal context is unambiguous
223 -- if there is only one applicable fixed point type. Determining whether
224 -- there is only one requires a search over all visible entities, and
225 -- happens only in very pathological cases (see 6115-006).
227 function Valid_Conversion
231 -- Verify legality rules given in 4.6 (8-23). Target is the target
232 -- type of the conversion, which may be an implicit conversion of
233 -- an actual parameter to an anonymous access type (in which case
234 -- N denotes the actual parameter and N = Operand).
236 -------------------------
237 -- Ambiguous_Character --
238 -------------------------
243 begin
247 -- First the ones in Standard
249 Error_Msg_N
251 Error_Msg_N
254 -- Include Wide_Wide_Character in Ada 2005 mode
257 Error_Msg_N
261 -- Now any other types that match
271 -------------------------
272 -- Analyze_And_Resolve --
273 -------------------------
276 begin
282 begin
287 -- Version withs check(s) suppressed
289 procedure Analyze_And_Resolve
293 is
296 begin
298 declare
300 begin
306 else
307 declare
310 begin
318 and then Scope_Is_Transient
319 then
320 -- This can only happen if a transient scope was created
321 -- for an inner expression, which will be removed upon
322 -- completion of the analysis of an enclosing construct.
323 -- The transient scope must have the suppress status of
324 -- the enclosing environment, not of this Analyze call.
327 Scope_Suppress;
331 procedure Analyze_And_Resolve
334 is
337 begin
339 declare
341 begin
347 else
348 declare
351 begin
359 and then Scope_Is_Transient
360 then
362 Scope_Suppress;
366 ----------------------------
367 -- Check_Discriminant_Use --
368 ----------------------------
376 begin
377 -- Any use in a default expression is legal
384 -- Discriminant cannot be used to constrain a scalar type
391 then
396 -- The following check catches the unusual case where
397 -- a discriminant appears within an index constraint
398 -- that is part of a larger expression within a constraint
399 -- on a component, e.g. "C : Int range 1 .. F (new A(1 .. D))".
400 -- For now we only check case of record components, and
401 -- note that a similar check should also apply in the
402 -- case of discriminant constraints below. ???
404 -- Note that the check for N_Subtype_Declaration below is to
405 -- detect the valid use of discriminants in the constraints of a
406 -- subtype declaration when this subtype declaration appears
407 -- inside the scope of a record type (which is syntactically
408 -- illegal, but which may be created as part of derived type
409 -- processing for records). See Sem_Ch3.Build_Derived_Record_Type
410 -- for more info.
414 and then not
416 and then
418 or else
421 then
422 Error_Msg_N
427 -- Detect a common beginner error:
429 -- type R (D : Positive := 100) is record
430 -- Name : String (1 .. D);
431 -- end record;
433 -- The default value causes an object of type R to be
434 -- allocated with room for Positive'Last characters.
436 declare
443 -- Return True if type T has a large enough range that
444 -- any array whose index type covered the whole range of
445 -- the type would likely raise Storage_Error.
447 ------------------------
448 -- Large_Storage_Type --
449 ------------------------
452 begin
453 return
454 T = Standard_Integer
455 or else
456 T = Standard_Positive
457 or else
461 begin
462 -- Check that the Disc has a large range
468 -- If the enclosing type is limited, we allocate only the
469 -- default value, not the maximum, and there is no need for
470 -- a warning.
476 -- Check that it is the high bound
480 then
484 -- Check the array allows a large range at this bound.
485 -- First find the array
499 -- Next, find the dimension
507 loop
516 -- Now, check the dimension has a large range
522 -- Warn about the danger
524 Error_Msg_N
534 -- Legal case is in index or discriminant constraint
538 then
540 Error_Msg_N
545 then
546 Error_Msg_N
552 -- Otherwise, context is an expression. It should not be within
553 -- (i.e. a subexpression of) a constraint for a component.
555 else
561 loop
567 -- If the discriminant is used in an expression that is a bound
568 -- of a scalar type, an Itype is created and the bounds are attached
569 -- to its range, not to the original subtype indication. Such use
570 -- is of course a double fault.
573 and then
575 or else
579 -- The constraint itself may be given by a subtype indication,
580 -- rather than by a more common discrete range.
583 and then
587 then
588 Error_Msg_N
594 --------------------------------
595 -- Check_For_Visible_Operator --
596 --------------------------------
599 begin
601 Error_Msg_NE
607 ----------------------------------
608 -- Check_Fully_Declared_Prefix --
609 ----------------------------------
611 procedure Check_Fully_Declared_Prefix
614 is
615 begin
616 -- Check that the designated type of the prefix of a dereference is
617 -- not an incomplete type. This cannot be done unconditionally, because
618 -- dereferences of private types are legal in default expressions. This
619 -- case is taken care of in Check_Fully_Declared, called below. There
620 -- are also 2005 cases where it is legal for the prefix to be unfrozen.
622 -- This consideration also applies to similar checks for allocators,
623 -- qualified expressions, and type conversions.
625 -- An additional exception concerns other per-object expressions that
626 -- are not directly related to component declarations, in particular
627 -- representation pragmas for tasks. These will be per-object
628 -- expressions if they depend on discriminants or some global entity.
629 -- If the task has access discriminants, the designated type may be
630 -- incomplete at the point the expression is resolved. This resolution
631 -- takes place within the body of the initialization procedure, where
632 -- the discriminant is replaced by its discriminal.
636 then
639 -- Ada 2005 (AI-326): Tagged incomplete types allowed. The wrong usages
640 -- are handled by Analyze_Access_Attribute, Analyze_Assignment,
641 -- Analyze_Object_Renaming, and Freeze_Entity.
646 E_Incomplete_Type
648 then
650 else
655 ------------------------------
656 -- Check_Infinite_Recursion --
657 ------------------------------
664 -- Check whether list of actuals is identical to list of formals
665 -- of called function (which is also the enclosing scope).
667 ------------------------
668 -- Same_Argument_List --
669 ------------------------
676 begin
679 else
688 then
699 -- Start of processing for Check_Infinite_Recursion
701 begin
702 -- Loop moving up tree, quitting if something tells us we are
703 -- definitely not in an infinite recursion situation.
706 loop
714 then
719 then
720 -- If the call is the expression of a return statement and
721 -- the actuals are identical to the formals, it's worth a
722 -- warning. However, we skip this if there is an immediately
723 -- preceding raise statement, since the call is never executed.
725 -- Furthermore, this corresponds to a common idiom:
727 -- function F (L : Thing) return Boolean is
728 -- begin
729 -- raise Program_Error;
730 -- return F (L);
731 -- end F;
733 -- for generating a stub function
736 and then Same_Argument_List
737 then
740 -- OK, return statement is in a statement list, look for raise
742 declare
745 begin
746 -- Skip past N_Freeze_Entity nodes generated by expansion
751 loop
755 -- If no raise statement, give warning
758 and then
766 else
777 -------------------------------
778 -- Check_Initialization_Call --
779 -------------------------------
785 -- Check whether the creation of an object of the type will involve
786 -- use of the secondary stack. If T is a record type, this is true
787 -- if the expression for some component uses the secondary stack, eg.
788 -- through a call to a function that returns an unconstrained value.
789 -- False if T is controlled, because cleanups occur elsewhere.
791 -------------
792 -- Uses_SS --
793 -------------
800 begin
801 -- Normally we want to use the underlying type, but if it's not set
802 -- then continue with T.
819 then
820 -- The expression for a dynamic component may be rewritten
821 -- as a dereference, so retrieve original node.
825 -- Return True if the expression is a call to a function
826 -- (including an attribute function such as Image) with
827 -- a result that requires a transient scope.
833 then
846 else
851 -- Start of processing for Check_Initialization_Call
853 begin
854 -- Establish a transient scope if the type needs it
861 ------------------------------
862 -- Check_Parameterless_Call --
863 ------------------------------
869 -- If the prefix is of an access_to_subprogram type, the node must be
870 -- rewritten as a call. Ditto if the prefix is overloaded and all its
871 -- interpretations are access to subprograms.
873 ---------------------------
874 -- Prefix_Is_Access_Subp --
875 ---------------------------
881 begin
883 return
886 else
891 then
902 -- Start of processing for Check_Parameterless_Call
904 begin
905 -- Defend against junk stuff if errors already detected
912 then
919 -- If the context expects a value, and the name is a procedure,
920 -- this is most likely a missing 'Access. Do not try to resolve
921 -- the parameterless call, error will be caught when the outer
922 -- call is analyzed.
927 and then
931 then
935 -- Rewrite as call if overloadable entity that is (or could be, in
936 -- the overloaded case) a function call. If we know for sure that
937 -- the entity is an enumeration literal, we do not rewrite it.
944 -- Rewrite as call if it is an explicit deference of an expression of
945 -- a subprogram access type, and the suprogram type is not that of a
946 -- procedure or entry.
948 or else
951 -- Rewrite as call if it is a selected component which is a function,
952 -- this is the case of a call to a protected function (which may be
953 -- overloaded with other protected operations).
955 or else
958 or else
960 or else
964 -- If one of the above three conditions is met, rewrite as call.
965 -- Apply the rewriting only once.
967 then
970 then
973 -- If overloaded, overload set belongs to new copy
977 -- Change node to parameterless function call (note that the
978 -- Parameter_Associations associations field is left set to Empty,
979 -- its normal default value since there are no parameters)
992 ----------------------
993 -- Is_Predefined_Op --
994 ----------------------
997 begin
1005 -----------------------------
1006 -- Make_Call_Into_Operator --
1007 -----------------------------
1009 procedure Make_Call_Into_Operator
1013 is
1028 -- Determine whether E is an access type declared by an access decla-
1029 -- ration, and not an (anonymous) allocator type.
1032 -- If the operand is not universal, and the operator is given by a
1033 -- expanded name, verify that the operand has an interpretation with
1034 -- a type defined in the given scope of the operator.
1037 -- Find a type of the given class in the package Pack that contains
1038 -- the operator.
1040 -----------------------------
1041 -- Is_Definite_Access_Type --
1042 -----------------------------
1046 begin
1052 ---------------------------
1053 -- Operand_Type_In_Scope --
1054 ---------------------------
1061 begin
1065 else
1079 ---------------
1080 -- Type_In_P --
1081 ---------------
1087 -- Verify that node is not part of the type declaration for the
1088 -- candidate type, which would otherwise be invisible.
1090 -------------
1091 -- In_Decl --
1092 -------------
1098 begin
1107 else
1110 loop
1113 else
1122 -- Start of processing for Type_In_P
1124 begin
1125 -- If the context type is declared in the prefix package, this
1126 -- is the desired base type.
1130 then
1133 else
1137 and then not In_Decl
1138 then
1149 -- Start of processing for Make_Call_Into_Operator
1151 begin
1154 -- Binary operator
1164 -- Unary operator
1166 else
1172 -- If the operator is denoted by an expanded name, and the prefix is
1173 -- not Standard, but the operator is a predefined one whose scope is
1174 -- Standard, then this is an implicit_operator, inserted as an
1175 -- interpretation by the procedure of the same name. This procedure
1176 -- overestimates the presence of implicit operators, because it does
1177 -- not examine the type of the operands. Verify now that the operand
1178 -- type appears in the given scope. If right operand is universal,
1179 -- check the other operand. In the case of concatenation, either
1180 -- argument can be the component type, so check the type of the result.
1181 -- If both arguments are literals, look for a type of the right kind
1182 -- defined in the given scope. This elaborate nonsense is brought to
1183 -- you courtesy of b33302a. The type itself must be frozen, so we must
1184 -- find the type of the proper class in the given scope.
1186 -- A final wrinkle is the multiplication operator for fixed point
1187 -- types, which is defined in Standard only, and not in the scope of
1188 -- the fixed_point type itself.
1193 -- If the entity being called is defined in the given package,
1194 -- it is a renaming of a predefined operator, and known to be
1195 -- legal.
1199 then
1202 -- Visibility does not need to be checked in an instance: if the
1203 -- operator was not visible in the generic it has been diagnosed
1204 -- already, else there is an implicit copy of it in the instance.
1213 then
1218 -- Ada 2005, AI-420: Predefined equality on Universal_Access
1219 -- is available.
1224 then
1227 else
1236 and then Is_Binary
1238 then
1244 -- Verify that the scope contains a type that corresponds to
1245 -- the given literal. Optimize the case where Pack is Standard.
1267 else
1276 else
1285 then
1288 -- If the type is defined elsewhere, and the operator is not
1289 -- defined in the given scope (by a renaming declaration, e.g.)
1290 -- then this is an error as well. If an extension of System is
1291 -- present, and the type may be defined there, Pack must be
1292 -- System itself.
1299 then
1302 else
1308 then
1315 Error_Msg_NE
1326 else
1330 -- If this is a call to a function that renames a predefined equality,
1331 -- the renaming declaration provides a type that must be used to
1332 -- resolve the operands. This must be done now because resolution of
1333 -- the equality node will not resolve any remaining ambiguity, and it
1334 -- assumes that the first operand is not overloaded.
1339 then
1348 -- If this is an arithmetic operator and the result type is private,
1349 -- the operands and the result must be wrapped in conversion to
1350 -- expose the underlying numeric type and expand the proper checks,
1351 -- e.g. on division.
1355 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
1356 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
1365 else
1369 -- For predefined operators on literals, the operation freezes
1370 -- their type.
1378 -------------------
1379 -- Operator_Kind --
1380 -------------------
1382 function Operator_Kind
1385 is
1388 begin
1424 else
1428 -- Unary operators
1430 else
1439 else
1447 -----------------------------
1448 -- Pre_Analyze_And_Resolve --
1449 -----------------------------
1454 begin
1458 -- We suppress all checks for this analysis, since the checks will
1459 -- be applied properly, and in the right location, when the default
1460 -- expression is reanalyzed and reexpanded later on.
1464 Expander_Mode_Restore;
1468 -- Version without context type
1473 begin
1480 Expander_Mode_Restore;
1484 ----------------------------------
1485 -- Replace_Actual_Discriminants --
1486 ----------------------------------
1494 -------------------
1495 -- Process_Discr --
1496 -------------------
1501 begin
1507 then
1523 -- Start of processing for Replace_Actual_Discriminants
1525 begin
1539 else
1544 -------------
1545 -- Resolve --
1546 -------------
1562 -- Determine whether a node comes from a predefined library unit or
1563 -- Standard.
1566 -- Try and fix up a literal so that it matches its expected type. New
1567 -- literals are manufactured if necessary to avoid cascaded errors.
1570 -- Called when attempt at resolving current expression fails
1572 ------------------------------------
1573 -- Comes_From_Predefined_Lib_Unit --
1574 -------------------------------------
1577 begin
1578 return
1584 --------------------
1585 -- Patch_Up_Value --
1586 --------------------
1589 begin
1592 then
1601 then
1609 then
1614 Char_Literal_Value =>
1621 then
1632 -----------------------
1633 -- Resolution_Failed --
1634 -----------------------
1637 begin
1643 -- The caller will return without calling the expander, so we need
1644 -- to set the analyzed flag. Note that it is fine to set Analyzed
1645 -- to True even if we are in the middle of a shallow analysis,
1646 -- (see the spec of sem for more details) since this is an error
1647 -- situation anyway, and there is no point in repeating the
1648 -- analysis later (indeed it won't work to repeat it later, since
1649 -- we haven't got a clear resolution of which entity is being
1650 -- referenced.)
1656 -- Start of processing for Resolve
1658 begin
1663 -- Access attribute on remote subprogram cannot be used for
1664 -- a non-remote access-to-subprogram type.
1675 then
1676 Error_Msg_N
1682 -- If the context is a Remote_Access_To_Subprogram, access attributes
1683 -- must be resolved with the corresponding fat pointer. There is no need
1684 -- to check for the attribute name since the return type of an
1685 -- attribute is never a remote type.
1691 then
1692 declare
1700 begin
1701 -- Check that Typ is a remote access-to-subprogram type
1704 -- Prefix (N) must statically denote a remote subprogram
1705 -- declared in a package specification.
1722 or else
1724 then
1726 Error_Msg_N
1728 N);
1732 -- If we are generating code for a distributed program.
1733 -- perform semantic checks against the corresponding
1734 -- remote entities.
1739 and then Expander_Active
1741 then
1742 Check_Subtype_Conformant
1744 Old_Id => Designated_Type
1765 then
1770 -- Return if already analyzed
1776 -- Return if type = Any_Type (previous error encountered)
1785 -- If not overloaded, then we know the type, and all that needs doing
1786 -- is to check that this type is compatible with the context.
1792 -- In the overloaded case, we must select the interpretation that
1793 -- is compatible with the context (i.e. the type passed to Resolve)
1795 else
1796 -- Loop through possible interpretations
1801 -- We are only interested in interpretations that are compatible
1802 -- with the expected type, any other interpretations are ignored.
1807 Write_Eol;
1810 else
1811 -- Skip the current interpretation if it is disabled by an
1812 -- abstract operator. This action is performed only when the
1813 -- type against which we are resolving is the same as the
1814 -- type of the interpretation.
1821 then
1825 -- First matching interpretation
1833 -- Matching interpretation that is not the first, maybe an
1834 -- error, but there are some cases where preference rules are
1835 -- used to choose between the two possibilities. These and
1836 -- some more obscure cases are handled in Disambiguate.
1838 else
1839 -- If the current statement is part of a predefined library
1840 -- unit, then all interpretations which come from user level
1841 -- packages should not be considered.
1843 if From_Lib
1845 then
1852 -- Disambiguation has succeeded. Skip the remaining
1853 -- interpretations.
1863 else
1864 -- Before we issue an ambiguity complaint, check for
1865 -- the case of a subprogram call where at least one
1866 -- of the arguments is Any_Type, and if so, suppress
1867 -- the message, since it is a cascaded error.
1871 then
1872 declare
1876 begin
1888 Write_Eol;
1901 then
1906 then
1910 -- Not that special case, so issue message using the
1911 -- flag Ambiguous to control printing of the header
1912 -- message only at the start of an ambiguous set.
1917 then
1918 Error_Msg_N
1921 else
1922 Error_Msg_NE
1930 Error_Msg_N
1932 else
1939 -- By default, the error message refers to the candidate
1940 -- interpretation. But if it is a predefined operator, it
1941 -- is implicitly declared at the declaration of the type
1942 -- of the operand. Recover the sloc of that declaration
1943 -- for the error message.
1949 Standard_Standard
1950 then
1955 then
1963 Standard_Standard
1964 then
1969 then
1973 -- If this is an indirect call, use the subprogram_type
1974 -- in the message, to have a meaningful location.
1975 -- Indicate as well if this is an inherited operation,
1976 -- created by a type declaration.
1981 then
1983 Error_Msg_Sloc :=
1985 else
1992 then
1993 -- Special-case the message for universal_fixed
1994 -- operators, which are not declared with the type
1995 -- of the operand, but appear forever in Standard.
1999 then
2000 Error_Msg_N
2004 else
2005 Error_Msg_N
2009 elsif
2011 then
2012 Error_Msg_N
2014 else
2021 -- We have a matching interpretation, Expr_Type is the type
2022 -- from this interpretation, and Seen is the entity.
2024 -- For an operator, just set the entity name. The type will be
2025 -- set by the specific operator resolution routine.
2034 -- For an explicit dereference, attribute reference, range,
2035 -- short-circuit form (which is not an operator node), or call
2036 -- with a name that is an explicit dereference, there is
2037 -- nothing to be done at this point.
2048 then
2051 -- For procedure or function calls, set the type of the name,
2052 -- and also the entity pointer for the prefix
2058 then
2065 then
2070 -- For all other cases, just set the type of the Name
2072 else
2080 -- Move to next interpretation
2088 -- At this stage Found indicates whether or not an acceptable
2089 -- interpretation exists. If not, then we have an error, except
2090 -- that if the context is Any_Type as a result of some other error,
2091 -- then we suppress the error report.
2096 -- If type we are looking for is Void, then this is the procedure
2097 -- call case, and the error is simply that what we gave is not a
2098 -- procedure name (we think of procedure calls as expressions with
2099 -- types internally, but the user doesn't think of them this way!)
2103 -- Special case message if function used as a procedure
2108 then
2109 Error_Msg_NE
2113 -- Otherwise give general message (not clear what cases this
2114 -- covers, but no harm in providing for them!)
2116 else
2122 -- Otherwise we do have a subexpression with the wrong type
2124 -- Check for the case of an allocator which uses an access type
2125 -- instead of the designated type. This is a common error and we
2126 -- specialize the message, posting an error on the operand of the
2127 -- allocator, complaining that we expected the designated type of
2128 -- the allocator.
2134 then
2138 -- Check for view mismatch on Null in instances, for which the
2139 -- view-swapping mechanism has no identifier.
2145 then
2150 -- Check for an aggregate. Sometimes we can get bogus aggregates
2151 -- from misuse of parentheses, and we are about to complain about
2152 -- the aggregate without even looking inside it.
2154 -- Instead, if we have an aggregate of type Any_Composite, then
2155 -- analyze and resolve the component fields, and then only issue
2156 -- another message if we get no errors doing this (otherwise
2157 -- assume that the errors in the aggregate caused the problem).
2161 then
2162 -- Disable expansion in any case. If there is a type mismatch
2163 -- it may be fatal to try to expand the aggregate. The flag
2164 -- would otherwise be set to false when the error is posted.
2168 declare
2170 -- Check one aggregate, and set Found to True if we have a
2171 -- definite error in any of its elements
2174 -- Check one element of aggregate and set Found to True if
2175 -- we definitely have an error in the element.
2177 ----------------
2178 -- Check_Aggr --
2179 ----------------
2184 begin
2197 -- If this is a default-initialized component, then
2198 -- there is nothing to check. The box will be
2199 -- replaced by the appropriate call during late
2200 -- expansion.
2211 ----------------
2212 -- Check_Elmt --
2213 ----------------
2216 begin
2217 -- If we have a nested aggregate, go inside it (to
2218 -- attempt a naked analyze-resolve of the aggregate
2219 -- can cause undesirable cascaded errors). Do not
2220 -- resolve expression if it needs a type from context,
2221 -- as for integer * fixed expression.
2226 else
2231 then
2241 begin
2246 -- If an error message was issued already, Found got reset
2247 -- to True, so if it is still False, issue the standard
2248 -- Wrong_Type message.
2253 then
2254 declare
2256 begin
2262 -- Protected operation: retrieve operation name
2265 else
2275 declare
2279 begin
2286 Error_Msg_NE
2292 else
2295 else
2301 Resolution_Failed;
2304 -- Test if we have more than one interpretation for the context
2307 Resolution_Failed;
2310 -- Here we have an acceptable interpretation for the context
2312 else
2313 -- Propagate type information and normalize tree for various
2314 -- predefined operations. If the context only imposes a class of
2315 -- types, rather than a specific type, propagate the actual type
2316 -- downward.
2323 then
2326 -- Any_Fixed is legal in a real context only if a specific
2327 -- fixed point type is imposed. If Norman Cohen can be
2328 -- confused by this, it deserves a separate message.
2332 then
2339 -- A user-defined operator is tranformed into a function call at
2340 -- this point, so that further processing knows that operators are
2341 -- really operators (i.e. are predefined operators). User-defined
2342 -- operators that are intrinsic are just renamings of the predefined
2343 -- ones, and need not be turned into calls either, but if they rename
2344 -- a different operator, we must transform the node accordingly.
2345 -- Instantiations of Unchecked_Conversion are intrinsic but are
2346 -- treated as functions, even if given an operator designator.
2351 then
2357 and then
2359 = N_Subprogram_Renaming_Declaration
2360 then
2363 -- If the node is rewritten, it will be fully resolved in
2364 -- Rewrite_Renamed_Operator.
2374 when N_Aggregate => Resolve_Aggregate (N, Ctx_Type);
2376 when N_Allocator => Resolve_Allocator (N, Ctx_Type);
2378 when N_And_Then | N_Or_Else
2379 => Resolve_Short_Circuit (N, Ctx_Type);
2381 when N_Attribute_Reference
2382 => Resolve_Attribute (N, Ctx_Type);
2384 when N_Character_Literal
2385 => Resolve_Character_Literal (N, Ctx_Type);
2387 when N_Conditional_Expression
2388 => Resolve_Conditional_Expression (N, Ctx_Type);
2390 when N_Expanded_Name
2391 => Resolve_Entity_Name (N, Ctx_Type);
2393 when N_Extension_Aggregate
2394 => Resolve_Extension_Aggregate (N, Ctx_Type);
2396 when N_Explicit_Dereference
2397 => Resolve_Explicit_Dereference (N, Ctx_Type);
2399 when N_Function_Call
2400 => Resolve_Call (N, Ctx_Type);
2402 when N_Identifier
2403 => Resolve_Entity_Name (N, Ctx_Type);
2405 when N_Indexed_Component
2406 => Resolve_Indexed_Component (N, Ctx_Type);
2408 when N_Integer_Literal
2409 => Resolve_Integer_Literal (N, Ctx_Type);
2411 when N_Membership_Test
2412 => Resolve_Membership_Op (N, Ctx_Type);
2414 when N_Null => Resolve_Null (N, Ctx_Type);
2416 when N_Op_And | N_Op_Or | N_Op_Xor
2417 => Resolve_Logical_Op (N, Ctx_Type);
2419 when N_Op_Eq | N_Op_Ne
2420 => Resolve_Equality_Op (N, Ctx_Type);
2422 when N_Op_Lt | N_Op_Le | N_Op_Gt | N_Op_Ge
2423 => Resolve_Comparison_Op (N, Ctx_Type);
2425 when N_Op_Not => Resolve_Op_Not (N, Ctx_Type);
2427 when N_Op_Add | N_Op_Subtract | N_Op_Multiply |
2428 N_Op_Divide | N_Op_Mod | N_Op_Rem
2430 => Resolve_Arithmetic_Op (N, Ctx_Type);
2432 when N_Op_Concat => Resolve_Op_Concat (N, Ctx_Type);
2434 when N_Op_Expon => Resolve_Op_Expon (N, Ctx_Type);
2436 when N_Op_Plus | N_Op_Minus | N_Op_Abs
2437 => Resolve_Unary_Op (N, Ctx_Type);
2439 when N_Op_Shift => Resolve_Shift (N, Ctx_Type);
2441 when N_Procedure_Call_Statement
2442 => Resolve_Call (N, Ctx_Type);
2444 when N_Operator_Symbol
2445 => Resolve_Operator_Symbol (N, Ctx_Type);
2447 when N_Qualified_Expression
2448 => Resolve_Qualified_Expression (N, Ctx_Type);
2450 when N_Raise_xxx_Error
2451 => Set_Etype (N, Ctx_Type);
2453 when N_Range => Resolve_Range (N, Ctx_Type);
2455 when N_Real_Literal
2456 => Resolve_Real_Literal (N, Ctx_Type);
2458 when N_Reference => Resolve_Reference (N, Ctx_Type);
2460 when N_Selected_Component
2461 => Resolve_Selected_Component (N, Ctx_Type);
2463 when N_Slice => Resolve_Slice (N, Ctx_Type);
2465 when N_String_Literal
2466 => Resolve_String_Literal (N, Ctx_Type);
2468 when N_Subprogram_Info
2469 => Resolve_Subprogram_Info (N, Ctx_Type);
2471 when N_Type_Conversion
2472 => Resolve_Type_Conversion (N, Ctx_Type);
2474 when N_Unchecked_Expression =>
2475 Resolve_Unchecked_Expression (N, Ctx_Type);
2477 when N_Unchecked_Type_Conversion =>
2478 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
2480 end case;
2482 -- If the subexpression was replaced by a non-subexpression, then
2483 -- all we do is to expand it. The only legitimate case we know of
2484 -- is converting procedure call statement to entry call statements,
2485 -- but there may be others, so we are making this test general.
2487 if Nkind (N) not in N_Subexpr then
2488 Debug_A_Exit ("resolving ", N, " (done)");
2489 Expand (N);
2490 return;
2491 end if;
2493 -- The expression is definitely NOT overloaded at this point, so
2494 -- we reset the Is_Overloaded flag to avoid any confusion when
2495 -- reanalyzing the node.
2497 Set_Is_Overloaded (N, False);
2499 -- Freeze expression type, entity if it is a name, and designated
2500 -- type if it is an allocator (RM 13.14(10,11,13)).
2502 -- Now that the resolution of the type of the node is complete,
2503 -- and we did not detect an error, we can expand this node. We
2504 -- skip the expand call if we are in a default expression, see
2505 -- section "Handling of Default Expressions" in Sem spec.
2507 Debug_A_Exit ("resolving ", N, " (done)");
2509 -- We unconditionally freeze the expression, even if we are in
2510 -- default expression mode (the Freeze_Expression routine tests
2511 -- this flag and only freezes static types if it is set).
2513 Freeze_Expression (N);
2515 -- Now we can do the expansion
2517 Expand (N);
2518 end if;
2519 end Resolve;
2521 -------------
2522 -- Resolve --
2523 -------------
2525 -- Version with check(s) suppressed
2527 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
2528 begin
2529 if Suppress = All_Checks then
2530 declare
2531 Svg : constant Suppress_Array := Scope_Suppress;
2532 begin
2533 Scope_Suppress := (others => True);
2534 Resolve (N, Typ);
2535 Scope_Suppress := Svg;
2536 end;
2538 else
2539 declare
2540 Svg : constant Boolean := Scope_Suppress (Suppress);
2541 begin
2542 Scope_Suppress (Suppress) := True;
2543 Resolve (N, Typ);
2544 Scope_Suppress (Suppress) := Svg;
2545 end;
2546 end if;
2547 end Resolve;
2549 -------------
2550 -- Resolve --
2551 -------------
2553 -- Version with implicit type
2555 procedure Resolve (N : Node_Id) is
2556 begin
2557 Resolve (N, Etype (N));
2558 end Resolve;
2560 ---------------------
2561 -- Resolve_Actuals --
2562 ---------------------
2564 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
2565 Loc : constant Source_Ptr := Sloc (N);
2566 A : Node_Id;
2567 F : Entity_Id;
2568 A_Typ : Entity_Id;
2569 F_Typ : Entity_Id;
2570 Prev : Node_Id := Empty;
2572 procedure Check_Prefixed_Call;
2573 -- If the original node is an overloaded call in prefix notation,
2575 -- Try_Object_Operation has already verified that there is a valid
2576 -- interpretation, but the form of the actual can only be determined
2577 -- once the primitive operation is identified.
2580 -- If the actual is missing in a call, insert in the actuals list
2581 -- an instance of the default expression. The insertion is always
2582 -- a named association.
2585 -- Check whether T1 and T2, or their full views, are derived from a
2586 -- common type. Used to enforce the restrictions on array conversions
2587 -- of AI95-00246.
2589 -------------------------
2590 -- Check_Prefixed_Call --
2591 -------------------------
2600 begin
2601 -- Check whether the call is a prefixed call, with or without
2602 -- additional actuals.
2605 or else
2611 then
2614 then
2615 -- Introduce dereference on object in prefix
2617 New_A :=
2625 then
2626 -- Introduce an implicit 'Access in prefix
2629 Error_Msg_NE
2645 --------------------
2646 -- Insert_Default --
2647 --------------------
2653 begin
2654 -- Missing argument in call, nothing to insert
2659 else
2660 -- Note that we do a full New_Copy_Tree, so that any associated
2661 -- Itypes are properly copied. This may not be needed any more,
2662 -- but it does no harm as a safety measure! Defaults of a generic
2663 -- formal may be out of bounds of the corresponding actual (see
2664 -- cc1311b) and an additional check may be required.
2666 Actval :=
2667 New_Copy_Tree
2674 then
2680 then
2683 then
2684 -- If default is a real literal, do not introduce a
2685 -- conversion whose effect may depend on the run-time
2686 -- size of universal real.
2690 else
2701 -- Resolve aggregates with their base type, to avoid scope
2702 -- anomalies: the subtype was first built in the suprogram
2703 -- declaration, and the current call may be nested.
2707 then
2709 else
2713 else
2716 -- See note above concerning aggregates
2720 then
2723 -- Resolve entities with their own type, which may differ
2724 -- from the type of a reference in a generic context (the
2725 -- view swapping mechanism did not anticipate the re-analysis
2726 -- of default values in calls).
2731 else
2736 -- If default is a tag indeterminate function call, propagate
2737 -- tag to obtain proper dispatching.
2741 then
2747 -- If the default expression raises constraint error, then just
2748 -- silently replace it with an N_Raise_Constraint_Error node,
2749 -- since we already gave the warning on the subprogram spec.
2759 Assoc :=
2764 -- Case of insertion is first named actual
2768 then
2775 else
2779 else
2783 -- Case of insertion is not first named actual
2785 else
2786 Set_Next_Named_Actual
2798 -------------------
2799 -- Same_Ancestor --
2800 -------------------
2806 begin
2809 then
2815 then
2822 -- Start of processing for Resolve_Actuals
2824 begin
2826 Check_Prefixed_Call;
2835 -- If we have an error in any actual or formal, indicated by
2836 -- a type of Any_Type, then abandon resolution attempt, and
2837 -- set result type to Any_Type.
2841 then
2846 -- Case where actual is present
2850 or else
2852 then
2853 -- If the formal is Out or In_Out, do not resolve and expand the
2854 -- conversion, because it is subsequently expanded into explicit
2855 -- temporaries and assignments. However, the object of the
2856 -- conversion can be resolved. An exception is the case of tagged
2857 -- type conversion with a class-wide actual. In that case we want
2858 -- the tag check to occur and no temporary will be needed (no
2859 -- representation change can occur) and the parameter is passed by
2860 -- reference, so we go ahead and resolve the type conversion.
2861 -- Another exception is the case of reference to component or
2862 -- subcomponent of a bit-packed array, in which case we want to
2863 -- defer expansion to the point the in and out assignments are
2864 -- performed.
2869 then
2872 then
2875 then
2877 Error_Msg_N
2881 -- Ada 2005: rule is relaxed (see AI-363)
2884 and then
2886 then
2887 Error_Msg_N
2890 Error_Msg_N
2895 and then
2898 then
2899 Error_Msg_N
2908 then
2912 -- If the actual is a function call that returns a limited
2913 -- unconstrained object that needs finalization, create a
2914 -- transient scope for it, so that it can receive the proper
2915 -- finalization list.
2920 and then Expander_Active
2921 and then
2923 then
2926 else
2930 and then
2933 then
2934 Error_Msg_N
2947 -- (Ada 2005: AI-251): If the actual is an allocator whose
2948 -- directly designated type is a class-wide interface, we build
2949 -- an anonymous access type to use it as the type of the
2950 -- allocator. Later, when the subprogram call is expanded, if
2951 -- the interface has a secondary dispatch table the expander
2952 -- will add a type conversion to force the correct displacement
2953 -- of the pointer.
2956 declare
2960 begin
2963 then
2972 -- Ada 2005, AI-162:If the actual is an allocator, the
2973 -- innermost enclosing statement is the master of the
2974 -- created object. This needs to be done with expansion
2975 -- enabled only, otherwise the transient scope will not
2976 -- be removed in the expansion of the wrapped construct.
2980 and then Expander_Active
2981 then
2987 -- (Ada 2005): The call may be to a primitive operation of
2988 -- a tagged synchronized type, declared outside of the type.
2989 -- In this case the controlling actual must be converted to
2990 -- its corresponding record type, which is the formal type.
2994 then
2996 Unchecked_Convert_To
3006 -- Perform error checks for IN and IN OUT parameters
3010 -- Check unset reference. For scalar parameters, it is clearly
3011 -- wrong to pass an uninitialized value as either an IN or
3012 -- IN-OUT parameter. For composites, it is also clearly an
3013 -- error to pass a completely uninitialized value as an IN
3014 -- parameter, but the case of IN OUT is trickier. We prefer
3015 -- not to give a warning here. For example, suppose there is
3016 -- a routine that sets some component of a record to False.
3017 -- It is perfectly reasonable to make this IN-OUT and allow
3018 -- either initialized or uninitialized records to be passed
3019 -- in this case.
3021 -- For partially initialized composite values, we also avoid
3022 -- warnings, since it is quite likely that we are passing a
3023 -- partially initialized value and only the initialized fields
3024 -- will in fact be read in the subprogram.
3029 then
3033 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
3034 -- actual to a nested call, since this is case of reading an
3035 -- out parameter, which is not allowed.
3040 then
3047 then
3052 else
3053 Kill_All_Checks;
3062 -- Apply appropriate range checks for in, out, and in-out
3063 -- parameters. Out and in-out parameters also need a separate
3064 -- check, if there is a type conversion, to make sure the return
3065 -- value meets the constraints of the variable before the
3066 -- conversion.
3068 -- Gigi looks at the check flag and uses the appropriate types.
3069 -- For now since one flag is used there is an optimization which
3070 -- might not be done in the In Out case since Gigi does not do
3071 -- any analysis. More thought required about this ???
3075 then
3087 then
3093 then
3099 then
3102 else
3106 -- Ada 2005 (AI-231)
3112 then
3113 Apply_Compile_Time_Constraint_Error
3123 then
3126 Apply_Scalar_Range_Check
3128 else
3129 Apply_Range_Check
3133 else
3139 then
3142 else
3148 -- An actual associated with an access parameter is implicitly
3149 -- converted to the anonymous access type of the formal and
3150 -- must satisfy the legality checks for access conversions.
3154 Error_Msg_N
3159 -- Check bad case of atomic/volatile argument (RM C.6(12))
3163 then
3166 then
3167 Error_Msg_N
3169 N);
3173 then
3174 Error_Msg_N
3176 N);
3180 -- Check that subprograms don't have improper controlling
3181 -- arguments (RM 3.9.2 (9))
3183 -- A primitive operation may have an access parameter of an
3184 -- incomplete tagged type, but a dispatching call is illegal
3185 -- if the type is still incomplete.
3191 declare
3193 begin
3197 then
3198 Error_Msg_NE
3212 then
3217 then
3219 Error_Msg_NE
3229 and then
3233 then
3234 Error_Msg_N
3239 then
3241 Error_Msg_NE
3248 -- If it is a named association, treat the selector_name as
3249 -- a proper identifier, and mark the corresponding entity.
3266 -- Case where actual is not present
3268 else
3269 Insert_Default;
3276 -----------------------
3277 -- Resolve_Allocator --
3278 -----------------------
3289 procedure Check_Allocator_Discrim_Accessibility
3292 -- Check that accessibility level associated with an access discriminant
3293 -- initialized in an allocator by the expression Disc_Exp is not deeper
3294 -- than the level of the allocator type Alloc_Typ. An error message is
3295 -- issued if this condition is violated. Specialized checks are done for
3296 -- the cases of a constraint expression which is an access attribute or
3297 -- an access discriminant.
3300 -- If the allocator is an actual in a call, it is allowed to be class-
3301 -- wide when the context is not because it is a controlling actual.
3304 -- Propagate all nested coextensions which are located one nesting
3305 -- level down the tree to the node Root. Example:
3306 --
3307 -- Top_Record
3308 -- Level_1_Coextension
3309 -- Level_2_Coextension
3310 --
3311 -- The algorithm is paired with delay actions done by the Expander. In
3312 -- the above example, assume all coextensions are controlled types.
3313 -- The cycle of analysis, resolution and expansion will yield:
3314 --
3315 -- 1) Analyze Top_Record
3316 -- 2) Analyze Level_1_Coextension
3317 -- 3) Analyze Level_2_Coextension
3318 -- 4) Resolve Level_2_Coextnesion. The allocator is marked as a
3319 -- coextension.
3320 -- 5) Expand Level_2_Coextension. A temporary variable Temp_1 is
3321 -- generated to capture the allocated object. Temp_1 is attached
3322 -- to the coextension chain of Level_2_Coextension.
3323 -- 6) Resolve Level_1_Coextension. The allocator is marked as a
3324 -- coextension. A forward tree traversal is performed which finds
3325 -- Level_2_Coextension's list and copies its contents into its
3326 -- own list.
3327 -- 7) Expand Level_1_Coextension. A temporary variable Temp_2 is
3328 -- generated to capture the allocated object. Temp_2 is attached
3329 -- to the coextension chain of Level_1_Coextension. Currently, the
3330 -- contents of the list are [Temp_2, Temp_1].
3331 -- 8) Resolve Top_Record. A forward tree traversal is performed which
3332 -- finds Level_1_Coextension's list and copies its contents into
3333 -- its own list.
3334 -- 9) Expand Top_Record. Generate finalization calls for Temp_1 and
3335 -- Temp_2 and attach them to Top_Record's finalization list.
3337 -------------------------------------------
3338 -- Check_Allocator_Discrim_Accessibility --
3339 -------------------------------------------
3341 procedure Check_Allocator_Discrim_Accessibility
3344 is
3345 begin
3348 then
3349 Error_Msg_N
3352 -- When the expression is an Access attribute the level of the prefix
3353 -- object must not be deeper than that of the allocator's type.
3357 = Attribute_Access
3360 then
3361 Error_Msg_N
3363 Disc_Exp);
3365 -- When the expression is an access discriminant the check is against
3366 -- the level of the prefix object.
3372 then
3373 Error_Msg_N
3375 Disc_Exp);
3377 -- All other cases are legal
3379 else
3384 ----------------------------
3385 -- In_Dispatching_Context --
3386 ----------------------------
3390 begin
3397 ----------------------------
3398 -- Propagate_Coextensions --
3399 ----------------------------
3404 -- Copy the contents of list From into list To, preserving the
3405 -- order of elements.
3408 -- Recognize an allocator or a rewritten allocator node and add it
3409 -- allong with its nested coextensions to the list of Root.
3411 ---------------
3412 -- Copy_List --
3413 ---------------
3417 begin
3425 -----------------------
3426 -- Process_Allocator --
3427 -----------------------
3432 begin
3433 -- This is a possible rewritten subtype indication allocator. Any
3434 -- nested coextensions will appear as discriminant constraints.
3439 then
3440 declare
3444 begin
3446 Discr_Elmt :=
3456 then
3461 Copy_List
3469 -- There is no need to continue the traversal of this
3470 -- subtree since all the information has already been
3471 -- propagated.
3477 -- Case of either a stand alone allocator or a rewritten allocator
3478 -- with an aggregate.
3480 else
3487 -- Propagate the list of nested coextensions to the Root
3488 -- allocator. This is done through list copy since a single
3489 -- allocator may have multiple coextensions. Do not touch
3490 -- coextensions roots.
3494 then
3499 Copy_List
3504 -- There is no need to continue the traversal of this
3505 -- subtree since all the information has already been
3506 -- propagated.
3512 -- Keep on traversing, looking for the next allocator
3520 -- Start of processing for Propagate_Coextensions
3522 begin
3526 -- Start of processing for Resolve_Allocator
3528 begin
3529 -- Replace general access with specific type
3539 -- For qualified expression, resolve the expression using the
3540 -- given subtype (nothing to do for type mark, subtype indication)
3545 and then not In_Dispatching_Context
3546 then
3547 Error_Msg_N
3554 -- A qualified expression requires an exact match of the type,
3555 -- class-wide matching is not allowed.
3560 then
3564 -- A special accessibility check is needed for allocators that
3565 -- constrain access discriminants. The level of the type of the
3566 -- expression used to constrain an access discriminant cannot be
3567 -- deeper than the type of the allocator (in constrast to access
3568 -- parameters, where the level of the actual can be arbitrary).
3570 -- We can't use Valid_Conversion to perform this check because
3571 -- in general the type of the allocator is unrelated to the type
3572 -- of the access discriminant.
3576 then
3582 and then
3584 or else
3586 then
3589 -- Get the first component expression of the aggregate
3599 else
3603 else
3622 else
3627 else
3636 -- For a subtype mark or subtype indication, freeze the subtype
3638 else
3642 Error_Msg_N
3646 -- A special accessibility check is needed for allocators that
3647 -- constrain access discriminants. The level of the type of the
3648 -- expression used to constrain an access discriminant cannot be
3649 -- deeper than the type of the allocator (in constrast to access
3650 -- parameters, where the level of the actual can be arbitrary).
3651 -- We can't use Valid_Conversion to perform this check because
3652 -- in general the type of the allocator is unrelated to the type
3653 -- of the access discriminant.
3658 then
3668 else
3682 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
3683 -- check that the level of the type of the created object is not deeper
3684 -- than the level of the allocator's access type, since extensions can
3685 -- now occur at deeper levels than their ancestor types. This is a
3686 -- static accessibility level check; a run-time check is also needed in
3687 -- the case of an initialized allocator with a class-wide argument (see
3688 -- Expand_Allocator_Expression).
3692 then
3693 declare
3696 begin
3701 else
3710 E);
3716 -- Do not apply Ada 2005 accessibility checks on a class-wide
3717 -- allocator if the type given in the allocator is a formal
3718 -- type. A run-time check will be performed in the instance.
3728 -- Check for allocation from an empty storage pool
3731 declare
3733 begin
3741 -- If the context is an unchecked conversion, as may happen within
3742 -- an inlined subprogram, the allocator is being resolved with its
3743 -- own anonymous type. In that case, if the target type has a specific
3744 -- storage pool, it must be inherited explicitly by the allocator type.
3748 then
3749 Set_Associated_Storage_Pool
3753 -- An erroneous allocator may be rewritten as a raise Program_Error
3754 -- statement.
3758 -- An anonymous access discriminant is the definition of a
3759 -- coextension.
3763 N_Discriminant_Specification
3764 then
3765 -- Avoid marking an allocator as a dynamic coextension if it is
3766 -- within a static construct.
3772 -- Cleanup for potential static coextensions
3774 else
3779 -- There is no need to propagate any nested coextensions if they
3780 -- are marked as static since they will be rewritten on the spot.
3788 ---------------------------
3789 -- Resolve_Arithmetic_Op --
3790 ---------------------------
3792 -- Used for resolving all arithmetic operators except exponentiation
3803 -- We do the resolution using the base type, because intermediate values
3804 -- in expressions always are of the base type, not a subtype of it.
3807 -- Returns True if N is in a context that expects "any real type"
3810 -- Return True iff given type is Integer or universal real/integer
3813 -- Choose type of integer literal in fixed-point operation to conform
3814 -- to available fixed-point type. T is the type of the other operand,
3815 -- which is needed to determine the expected type of N.
3818 -- Set operand type to T if universal
3820 -------------------------------
3821 -- Expected_Type_Is_Any_Real --
3822 -------------------------------
3825 begin
3826 -- N is the expression after "delta" in a fixed_point_definition;
3827 -- see RM-3.5.9(6):
3832 -- N is one of the bounds in a real_range_specification;
3833 -- see RM-3.5.7(5):
3837 -- N is the expression of a delta_constraint;
3838 -- see RM-J.3(3):
3843 -----------------------------
3844 -- Is_Integer_Or_Universal --
3845 -----------------------------
3852 begin
3858 else
3864 then
3875 ----------------------------
3876 -- Set_Mixed_Mode_Operand --
3877 ----------------------------
3883 begin
3886 -- A universal integer literal is resolved as standard integer
3887 -- except in the case of a fixed-point result, where we leave it
3888 -- as universal (to be handled by Exp_Fixd later on)
3892 else
3900 then
3901 -- A universal real can appear in a fixed-type context. We resolve
3902 -- the literal with that context, even though this might raise an
3903 -- exception prematurely (the other operand may be zero).
3910 then
3911 -- Integer arg in mixed-mode operation. Resolve with universal
3912 -- type, in case preference rule must be applied.
3918 then
3919 -- Not a mixed-mode operation, resolve with context
3925 -- N may itself be a mixed-mode operation, so use context type
3932 then
3933 -- Must be (fixed * fixed) operation, operand must have one
3934 -- compatible interpretation.
3942 then
3943 -- C * F(X) in a fixed context, where C is a real literal or a
3944 -- fixed-point expression. F must have either a fixed type
3945 -- interpretation or an integer interpretation, but not both.
3953 else
3961 else
3969 -- Reanalyze the literal with the fixed type of the context. If
3970 -- context is Universal_Fixed, we are within a conversion, leave
3971 -- the literal as a universal real because there is no usable
3972 -- fixed type, and the target of the conversion plays no role in
3973 -- the resolution.
3975 declare
3979 begin
3982 else
3988 then
3990 else
3998 else
4003 ----------------------
4004 -- Set_Operand_Type --
4005 ----------------------
4008 begin
4011 then
4016 -- Start of processing for Resolve_Arithmetic_Op
4018 begin
4023 then
4027 -- Special-case for mixed-mode universal expressions or fixed point
4028 -- type operation: each argument is resolved separately. The same
4029 -- treatment is required if one of the operands of a fixed point
4030 -- operation is universal real, since in this case we don't do a
4031 -- conversion to a specific fixed-point type (instead the expander
4032 -- takes care of the case).
4038 then
4049 or else
4053 then
4058 -- If context is a fixed type and one operand is integer, the
4059 -- other is resolved with the type of the context.
4064 then
4071 then
4075 else
4080 -- Check the rule in RM05-4.5.5(19.1/2) disallowing the
4081 -- universal_fixed multiplying operators from being used when the
4082 -- expected type is also universal_fixed. Note that B_Typ will be
4083 -- Universal_Fixed in some cases where the expected type is actually
4084 -- Any_Real; Expected_Type_Is_Any_Real takes care of that case.
4088 then
4093 then
4094 Error_Msg_N
4096 Error_Msg_N
4102 else
4107 then
4108 Error_Msg_N
4111 N);
4114 -- The expected type is "any real type" in contexts like
4115 -- type T is delta <universal_fixed-expression> ...
4116 -- in which case we need to set the type to Universal_Real
4117 -- so that static expression evaluation will work properly.
4121 else
4130 or else
4132 then
4137 -- If no previous errors, this is only possible if one operand
4138 -- is overloaded and the context is universal. Resolve as such.
4143 else
4146 then
4150 -- If the context is Universal_Fixed and the operands are also
4151 -- universal fixed, this is an error, unless there is only one
4152 -- applicable fixed_point type (usually duration).
4156 then
4162 else
4167 else
4172 -- If one of the arguments was resolved to a non-universal type.
4173 -- label the result of the operation itself with the same type.
4174 -- Do the same for the universal argument, if any.
4185 -- Set overflow and division checking bit. Much cleverer code needed
4186 -- here eventually and perhaps the Resolve routines should be separated
4187 -- for the various arithmetic operations, since they will need
4188 -- different processing. ???
4195 -- Give warning if explicit division by zero
4201 then
4207 or else
4210 then
4211 -- Specialize the warning message according to the operation
4215 Apply_Compile_Time_Constraint_Error
4220 Apply_Compile_Time_Constraint_Error
4225 Apply_Compile_Time_Constraint_Error
4229 -- Division by zero can only happen with division, rem,
4230 -- and mod operations.
4236 -- Otherwise just set the flag to check at run time
4238 else
4248 ------------------
4249 -- Resolve_Call --
4250 ------------------
4262 begin
4263 -- The context imposes a unique interpretation with type Typ on a
4264 -- procedure or function call. Find the entity of the subprogram that
4265 -- yields the expected type, and propagate the corresponding formal
4266 -- constraints on the actuals. The caller has established that an
4267 -- interpretation exists, and emitted an error if not unique.
4269 -- First deal with the case of a call to an access-to-subprogram,
4270 -- dereference made explicit in Analyze_Call.
4276 else
4277 -- Find the interpretation whose type (a subprogram type) has a
4278 -- return type that is compatible with the context. Analysis of
4279 -- the node has established that one exists.
4298 -- If the prefix is not an entity, then resolve it
4304 -- For an indirect call, we always invalidate checks, since we do not
4305 -- know whether the subprogram is local or global. Yes we could do
4306 -- better here, e.g. by knowing that there are no local subprograms,
4307 -- but it does not seem worth the effort. Similarly, we kill all
4308 -- knowledge of current constant values.
4310 Kill_Current_Values;
4312 -- If this is a procedure call which is really an entry call, do
4313 -- the conversion of the procedure call to an entry call. Protected
4314 -- operations use the same circuitry because the name in the call
4315 -- can be an arbitrary expression with special resolution rules.
4321 then
4325 -- Kill checks and constant values, as above for indirect case
4326 -- Who knows what happens when another task is activated?
4328 Kill_Current_Values;
4331 -- Normal subprogram call with name established in Resolve
4337 -- Otherwise we must have the case of an overloaded call
4339 else
4355 -- Check that a call to Current_Task does not occur in an entry body
4358 declare
4361 begin
4363 loop
4370 then
4372 Error_Msg_NE
4375 Error_Msg_NE
4387 -- Check that a procedure call does not occur in the context of the
4388 -- entry call statement of a conditional or timed entry call. Note that
4389 -- the case of a call to a subprogram renaming of an entry will also be
4390 -- rejected. The test for N not being an N_Entry_Call_Statement is
4391 -- defensive, covering the possibility that the processing of entry
4392 -- calls might reach this point due to later modifications of the code
4393 -- above.
4398 then
4402 -- Ada 2005 (AI-345): If a procedure_call_statement is used
4403 -- for a procedure_or_entry_call, the procedure_name or pro-
4404 -- cedure_prefix of the procedure_call_statement shall denote
4405 -- an entry renamed by a procedure, or (a view of) a primitive
4406 -- subprogram of a limited interface whose first parameter is
4407 -- a controlling parameter.
4412 then
4413 Error_Msg_N
4418 -- Check that this is not a call to a protected procedure or
4419 -- entry from within a protected function.
4425 then
4431 -- Freeze the subprogram name if not in default expression. Note that we
4432 -- freeze procedure calls as well as function calls. Procedure calls are
4433 -- not frozen according to the rules (RM 13.14(14)) because it is
4434 -- impossible to have a procedure call to a non-frozen procedure in pure
4435 -- Ada, but in the code that we generate in the expander, this rule
4436 -- needs extending because we can generate procedure calls that need
4437 -- freezing.
4443 -- For a predefined operator, the type of the result is the type imposed
4444 -- by context, except for a predefined operation on universal fixed.
4445 -- Otherwise The type of the call is the type returned by the subprogram
4446 -- being called.
4453 -- If the subprogram returns an array type, and the context requires the
4454 -- component type of that array type, the node is really an indexing of
4455 -- the parameterless call. Resolve as such. A pathological case occurs
4456 -- when the type of the component is an access to the array type. In
4457 -- this case the call is truly ambiguous.
4460 and then
4465 and then
4468 then
4469 declare
4474 begin
4477 then
4478 Error_Msg_N
4480 else
4487 -- Indexed call to a parameterless function
4489 Index_Node :=
4491 Prefix =>
4495 else
4496 -- An Ada 2005 prefixed call to a primitive operation
4497 -- whose first parameter is the prefix. This prefix was
4498 -- prepended to the parameter list, which is actually a
4499 -- list of indices. Remove the prefix in order to build
4500 -- the proper indexed component.
4502 Index_Node :=
4504 Prefix =>
4507 Parameter_Associations =>
4508 New_List
4513 -- Since we are correcting a node classification error made
4514 -- by the parser, we call Replace rather than Rewrite.
4527 else
4531 -- In the case where the call is to an overloaded subprogram, Analyze
4532 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
4533 -- such a case Normalize_Actuals needs to be called once more to order
4534 -- the actuals correctly. Otherwise the call will have the ordering
4535 -- given by the last overloaded subprogram whether this is the correct
4536 -- one being called or not.
4543 -- In any case, call is fully resolved now. Reset Overload flag, to
4544 -- prevent subsequent overload resolution if node is analyzed again
4549 -- If we are calling the current subprogram from immediately within its
4550 -- body, then that is the case where we can sometimes detect cases of
4551 -- infinite recursion statically. Do not try this in case restriction
4552 -- No_Recursion is in effect anyway, and do it only for source calls.
4560 then
4561 -- Here we detected and flagged an infinite recursion, so we do
4562 -- not need to test the case below for further warnings.
4566 -- If call is to immediately containing subprogram, then check for
4567 -- the case of a possible run-time detectable infinite recursion.
4569 else
4573 -- Although in general case, recursion is not statically
4574 -- checkable, the case of calling an immediately containing
4575 -- subprogram is easy to catch.
4579 -- If the recursive call is to a parameterless subprogram,
4580 -- then even if we can't statically detect infinite
4581 -- recursion, this is pretty suspicious, and we output a
4582 -- warning. Furthermore, we will try later to detect some
4583 -- cases here at run time by expanding checking code (see
4584 -- Detect_Infinite_Recursion in package Exp_Ch6).
4586 -- If the recursive call is within a handler, do not emit a
4587 -- warning, because this is a common idiom: loop until input
4588 -- is correct, catch illegal input in handler and restart.
4594 then
4595 -- For the case of a procedure call. We give the message
4596 -- only if the call is the first statement in a sequence
4597 -- of statements, or if all previous statements are
4598 -- simple assignments. This is simply a heuristic to
4599 -- decrease false positives, without losing too many good
4600 -- warnings. The idea is that these previous statements
4601 -- may affect global variables the procedure depends on.
4605 then
4606 declare
4608 begin
4620 -- Do not give warning if we are in a conditional context
4622 declare
4624 begin
4630 then
4635 -- Here warning is to be issued
4638 Error_Msg_N
4640 Error_Msg_N
4652 -- If subprogram name is a predefined operator, it was given in
4653 -- functional notation. Replace call node with operator node, so
4654 -- that actuals can be resolved appropriately.
4662 then
4668 -- Create a transient scope if the resulting type requires it
4670 -- There are 4 notable exceptions: in init procs, the transient scope
4671 -- overhead is not needed and even incorrect due to the actual expansion
4672 -- of adjust calls; the second case is enumeration literal pseudo calls;
4673 -- the third case is intrinsic subprograms (Unchecked_Conversion and
4674 -- source information functions) that do not use the secondary stack
4675 -- even though the return type is unconstrained; the fourth case is a
4676 -- call to a build-in-place function, since such functions may allocate
4677 -- their result directly in a target object, and cases where the result
4678 -- does get allocated in the secondary stack are checked for within the
4679 -- specialized Exp_Ch6 procedures for expanding build-in-place calls.
4681 -- If this is an initialization call for a type whose initialization
4682 -- uses the secondary stack, we also need to create a transient scope
4683 -- for it, precisely because we will not do it within the init proc
4684 -- itself.
4686 -- If the subprogram is marked Inlined_Always, then even if it returns
4687 -- an unconstrained type the call does not require use of the secondary
4688 -- stack.
4694 then
4697 elsif Expander_Active
4702 and then not Within_Init_Proc
4704 then
4707 -- If the call appears within the bounds of a loop, it will
4708 -- be rewritten and reanalyzed, nothing left to do here.
4715 and then not Within_Init_Proc
4716 then
4720 -- A protected function cannot be called within the definition of the
4721 -- enclosing protected type.
4726 then
4727 Error_Msg_NE
4731 -- Propagate interpretation to actuals, and add default expressions
4732 -- where needed.
4737 -- Overloaded literals are rewritten as function calls, for
4738 -- purpose of resolution. After resolution, we can replace
4739 -- the call with the literal itself.
4745 -- Avoid validation, since it is a static function call
4751 -- If the subprogram is not global, then kill all saved values and
4752 -- checks. This is a bit conservative, since in many cases we could do
4753 -- better, but it is not worth the effort. Similarly, we kill constant
4754 -- values. However we do not need to do this for internal entities
4755 -- (unless they are inherited user-defined subprograms), since they
4756 -- are not in the business of molesting local values.
4758 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
4759 -- kill all checks and values for calls to global subprograms. This
4760 -- takes care of the case where an access to a local subprogram is
4761 -- taken, and could be passed directly or indirectly and then called
4762 -- from almost any context.
4764 -- Note: we do not do this step till after resolving the actuals. That
4765 -- way we still take advantage of the current value information while
4766 -- scanning the actuals.
4773 then
4774 Kill_Current_Values;
4777 -- If the subprogram is a primitive operation, check whether or not
4778 -- it is a correct dispatching call.
4782 then
4787 and then not In_Instance
4788 then
4792 -- If this is a dispatching call, generate the appropriate reference,
4793 -- for better source navigation in GPS.
4797 then
4799 else
4811 -------------------------------
4812 -- Resolve_Character_Literal --
4813 -------------------------------
4819 begin
4820 -- Verify that the character does belong to the type of the context
4825 -- Wide_Wide_Character literals must always be defined, since the set
4826 -- of wide wide character literals is complete, i.e. if a character
4827 -- literal is accepted by the parser, then it is OK for wide wide
4828 -- character (out of range character literals are rejected).
4833 -- Always accept character literal for type Any_Character, which
4834 -- occurs in error situations and in comparisons of literals, both
4835 -- of which should accept all literals.
4840 -- For Standard.Character or a type derived from it, check that
4841 -- the literal is in range
4848 -- For Standard.Wide_Character or a type derived from it, check
4849 -- that the literal is in range
4856 -- For Standard.Wide_Wide_Character or a type derived from it, we
4857 -- know the literal is in range, since the parser checked!
4862 -- If the entity is already set, this has already been resolved in
4863 -- a generic context, or comes from expansion. Nothing else to do.
4868 -- Otherwise we have a user defined character type, and we can use
4869 -- the standard visibility mechanisms to locate the referenced entity
4871 else
4884 -- If we fall through, then the literal does not match any of the
4885 -- entries of the enumeration type. This isn't just a constraint
4886 -- error situation, it is an illegality (see RM 4.2).
4888 Error_Msg_NE
4892 ---------------------------
4893 -- Resolve_Comparison_Op --
4894 ---------------------------
4896 -- Context requires a boolean type, and plays no role in resolution.
4897 -- Processing identical to that for equality operators. The result
4898 -- type is the base type, which matters when pathological subtypes of
4899 -- booleans with limited ranges are used.
4906 begin
4907 -- If this is an intrinsic operation which is not predefined, use
4908 -- the types of its declared arguments to resolve the possibly
4909 -- overloaded operands. Otherwise the operands are unambiguous and
4910 -- specify the expected type.
4915 else
4930 then
4933 else
4940 else
4951 ------------------------------------
4952 -- Resolve_Conditional_Expression --
4953 ------------------------------------
4960 begin
4969 -----------------------------------------
4970 -- Resolve_Discrete_Subtype_Indication --
4971 -----------------------------------------
4973 procedure Resolve_Discrete_Subtype_Indication
4976 is
4980 begin
4988 else
4998 Error_Msg_NE
5001 -- Rewrite the constraint as a range of Typ
5002 -- to allow compilation to proceed further.
5014 else
5018 -- Additionally, we must check that the bounds are compatible
5019 -- with the given subtype, which might be different from the
5020 -- type of the context.
5024 -- ??? If the above check statically detects a Constraint_Error
5025 -- it replaces the offending bound(s) of the range R with a
5026 -- Constraint_Error node. When the itype which uses these bounds
5027 -- is frozen the resulting call to Duplicate_Subexpr generates
5028 -- a new temporary for the bounds.
5030 -- Unfortunately there are other itypes that are also made depend
5031 -- on these bounds, so when Duplicate_Subexpr is called they get
5032 -- a forward reference to the newly created temporaries and Gigi
5033 -- aborts on such forward references. This is probably sign of a
5034 -- more fundamental problem somewhere else in either the order of
5035 -- itype freezing or the way certain itypes are constructed.
5037 -- To get around this problem we call Remove_Side_Effects right
5038 -- away if either bounds of R are a Constraint_Error.
5040 declare
5044 begin
5060 -------------------------
5061 -- Resolve_Entity_Name --
5062 -------------------------
5064 -- Used to resolve identifiers and expanded names
5069 begin
5070 -- If garbage from errors, set to Any_Type and return
5077 -- Replace named numbers by corresponding literals. Note that this is
5078 -- the one case where Resolve_Entity_Name must reset the Etype, since
5079 -- it is currently marked as universal.
5089 -- Allow use of subtype only if it is a concurrent type where we are
5090 -- currently inside the body. This will eventually be expanded
5091 -- into a call to Self (for tasks) or _object (for protected
5092 -- objects). Any other use of a subtype is invalid.
5097 then
5099 else
5100 Error_Msg_N
5104 -- Check discriminant use if entity is discriminant in current scope,
5105 -- i.e. discriminant of record or concurrent type currently being
5106 -- analyzed. Uses in corresponding body are unrestricted.
5111 then
5114 -- A parameterless generic function cannot appear in a context that
5115 -- requires resolution.
5126 then
5129 -- In all other cases, just do the possible static evaluation
5131 else
5132 -- A deferred constant that appears in an expression must have
5133 -- a completion, unless it has been removed by in-place expansion
5134 -- of an aggregate.
5140 and then not In_Default_Expression
5142 then
5147 then
5149 else
5150 Error_Msg_N (
5159 -------------------
5160 -- Resolve_Entry --
5161 -------------------
5173 -- If the bounds of the entry family being called depend on task
5174 -- discriminants, build a new index subtype where a discriminant is
5175 -- replaced with the value of the discriminant of the target task.
5176 -- The target task is the prefix of the entry name in the call.
5178 -----------------------
5179 -- Actual_Index_Type --
5180 -----------------------
5190 -- If the bound is given by a discriminant, replace with a reference
5191 -- to the discriminant of the same name in the target task.
5192 -- If the entry name is the target of a requeue statement and the
5193 -- entry is in the current protected object, the bound to be used
5194 -- is the discriminal of the object (see apply_range_checks for
5195 -- details of the transformation).
5197 -----------------------------
5198 -- Actual_Discriminant_Ref --
5199 -----------------------------
5205 begin
5210 then
5216 then
5219 else
5220 Ref :=
5230 -- Start of processing for Actual_Index_Type
5232 begin
5236 then
5239 else
5253 -- Start of processing of Resolve_Entry
5255 begin
5256 -- Find name of entry being called, and resolve prefix of name
5257 -- with its own type. The prefix can be overloaded, and the name
5258 -- and signature of the entry must be taken into account.
5262 -- Case of dealing with entry family within the current tasks
5266 else
5271 -- Entry call to an entry (or entry family) in the current task.
5272 -- This is legal even though the task will deadlock. Rewrite as
5273 -- call to current task.
5275 -- This can also be a call to an entry in an enclosing task.
5276 -- If this is a single task, we have to retrieve its name,
5277 -- because the scope of the entry is the task type, not the
5278 -- object. If the enclosing task is a task type, the identity
5279 -- of the task is given by its own self variable.
5281 -- Finally this can be a requeue on an entry of the same task
5282 -- or protected object.
5290 then
5291 -- S is an enclosing task or protected object. The concurrent
5292 -- declaration has been converted into a type declaration, and
5293 -- the object itself has an object declaration that follows
5294 -- the type in the same declarative part.
5306 -- Call to current task. Will be transformed into call to Self
5313 New_N :=
5316 Selector_Name =>
5323 then
5324 -- Use the entry name (which must be unique at this point) to
5325 -- find the prefix that returns the corresponding task type or
5326 -- protected type.
5328 declare
5334 begin
5356 -- Up to this point the expression could have been the actual
5357 -- in a simple entry call, and be given by a named association.
5361 else
5367 ------------------------
5368 -- Resolve_Entry_Call --
5369 ------------------------
5381 begin
5382 -- We kill all checks here, because it does not seem worth the
5383 -- effort to do anything better, an entry call is a big operation.
5385 Kill_All_Checks;
5387 -- Processing of the name is similar for entry calls and protected
5388 -- operation calls. Once the entity is determined, we can complete
5389 -- the resolution of the actuals.
5391 -- The selector may be overloaded, in the case of a protected object
5392 -- with overloaded functions. The type of the context is used for
5393 -- resolution.
5398 then
5399 declare
5403 begin
5422 -- Simple entry call
5430 -- Call to member of entry family
5437 -- We cannot in general check the maximum depth of protected entry
5438 -- calls at compile time. But we can tell that any protected entry
5439 -- call at all violates a specified nesting depth of zero.
5445 -- Use context type to disambiguate a protected function that can be
5446 -- called without actuals and that returns an array type, and where
5447 -- the argument list may be an indexing of the returned value.
5452 and then
5460 then
5461 declare
5464 begin
5465 Index_Node :=
5467 Prefix =>
5472 -- Since we are correcting a node classification error made by
5473 -- the parser, we call Replace rather than Rewrite.
5483 -- The operation name may have been overloaded. Order the actuals
5484 -- according to the formals of the resolved entity, and set the
5485 -- return type to that of the operation.
5498 then
5502 -- Verify that a procedure call cannot masquerade as an entry
5503 -- call where an entry call is expected.
5508 then
5513 then
5518 then
5523 -- After resolution, entry calls and protected procedure calls
5524 -- are changed into entry calls, for expansion. The structure
5525 -- of the node does not change, so it can safely be done in place.
5526 -- Protected function calls must keep their structure because they
5527 -- are subexpressions.
5531 -- A protected operation that is not a function may modify the
5532 -- corresponding object, and cannot apply to a constant.
5533 -- If this is an internal call, the prefix is the type itself.
5539 then
5540 Error_Msg_N
5542 Entry_Name);
5556 -- Protected functions can return on the secondary stack, in which
5557 -- case we must trigger the transient scope mechanism.
5559 elsif Expander_Active
5561 then
5566 -------------------------
5567 -- Resolve_Equality_Op --
5568 -------------------------
5570 -- Both arguments must have the same type, and the boolean context
5571 -- does not participate in the resolution. The first pass verifies
5572 -- that the interpretation is not ambiguous, and the type of the left
5573 -- argument is correctly set, or is Any_Type in case of ambiguity.
5574 -- If both arguments are strings or aggregates, allocators, or Null,
5575 -- they are ambiguous even though they carry a single (universal) type.
5576 -- Diagnose this case here.
5584 -- In the case of allocators, make a last-ditch attempt to find a single
5585 -- access type with the right designated type. This is semantically
5586 -- dubious, and of no interest to any real code, but c48008a makes it
5587 -- all worthwhile.
5589 -----------------------------
5590 -- Find_Unique_Access_Type --
5591 -----------------------------
5598 begin
5603 else
5615 then
5628 -- Start of processing for Resolve_Equality_Op
5630 begin
5642 then
5645 else
5655 then
5668 -- If the unique type is a class-wide type then it will be expanded
5669 -- into a dispatching call to the predefined primitive. Therefore we
5670 -- check here for potential violation of such restriction.
5676 if Warn_On_Redundant_Constructs
5681 then
5689 -- If this is an inequality, it may be the implicit inequality
5690 -- created for a user-defined operation, in which case the corres-
5691 -- ponding equality operation is not intrinsic, and the operation
5692 -- cannot be constant-folded. Else fold.
5697 or else Is_Intrinsic_Subprogram
5699 then
5703 then
5707 -- Ada 2005: If one operand is an anonymous access type, convert
5708 -- the other operand to it, to ensure that the underlying types
5709 -- match in the back-end. Same for access_to_subprogram, and the
5710 -- conversion verifies that the types are subtype conformant.
5712 -- We apply the same conversion in the case one of the operands is
5713 -- a private subtype of the type of the other.
5715 -- Why the Expander_Active test here ???
5717 if Expander_Active
5718 and then
5722 then
5742 ----------------------------------
5743 -- Resolve_Explicit_Dereference --
5744 ----------------------------------
5753 begin
5758 -- Use the context type to select the prefix that has the correct
5759 -- designated type.
5770 else
5771 -- If no interpretation covers the designated type of the prefix,
5772 -- this is the pathological case where not all implementations of
5773 -- the prefix allow the interpretation of the node as a call. Now
5774 -- that the expected type is known, Remove other interpretations
5775 -- from prefix, rewrite it as a call, and resolve again, so that
5776 -- the proper call node is generated.
5787 New_N :=
5789 Name =>
5802 else
5810 -- If the designated type is a packed unconstrained array type, and the
5811 -- explicit dereference is not in the context of an attribute reference,
5812 -- then we must compute and set the actual subtype, since it is needed
5813 -- by Gigi. The reason we exclude the attribute case is that this is
5814 -- handled fine by Gigi, and in fact we use such attributes to build the
5815 -- actual subtype. We also exclude generated code (which builds actual
5816 -- subtypes directly if they are needed).
5823 then
5827 -- Note: there is no Eval processing required for an explicit deference,
5828 -- because the type is known to be an allocators, and allocator
5829 -- expressions can never be static.
5833 -------------------------------
5834 -- Resolve_Indexed_Component --
5835 -------------------------------
5843 begin
5846 -- Use the context type to select the prefix that yields the correct
5847 -- component type.
5849 declare
5856 begin
5863 and then Covers
5865 then
5874 else
5880 else
5891 else
5898 -- If prefix is access type, dereference to get real array type.
5899 -- Note: we do not apply an access check because the expander always
5900 -- introduces an explicit dereference, and the check will happen there.
5906 -- If name was overloaded, set component type correctly now
5907 -- If a misplaced call to an entry family (which has no index typs)
5908 -- return. Error will be diagnosed from calling context.
5912 else
5919 -- The prefix may have resolved to a string literal, in which case its
5920 -- etype has a special representation. This is only possible currently
5921 -- if the prefix is a static concatenation, written in functional
5922 -- notation.
5927 else
5934 else
5943 -- Do not generate the warning on suspicious index if we are analyzing
5944 -- package Ada.Tags; otherwise we will report the warning with the
5945 -- Prims_Ptr field of the dispatch table.
5948 or else not
5950 Ada_Tags)
5951 then
5957 -----------------------------
5958 -- Resolve_Integer_Literal --
5959 -----------------------------
5962 begin
5967 --------------------------------
5968 -- Resolve_Intrinsic_Operator --
5969 --------------------------------
5977 begin
5987 -- If the operand type is private, rewrite with suitable conversions on
5988 -- the operands and the result, to expose the proper underlying numeric
5989 -- type.
5996 else
6012 then
6013 -- Add explicit conversion where needed, and save interpretations
6014 -- in case operands are overloaded.
6021 else
6027 else
6037 else
6042 --------------------------------------
6043 -- Resolve_Intrinsic_Unary_Operator --
6044 --------------------------------------
6046 procedure Resolve_Intrinsic_Unary_Operator
6049 is
6054 begin
6073 else
6078 ------------------------
6079 -- Resolve_Logical_Op --
6080 ------------------------
6086 begin
6087 -- Predefined operations on scalar types yield the base type. On the
6088 -- other hand, logical operations on arrays yield the type of the
6089 -- arguments (and the context).
6093 else
6097 -- The following test is required because the operands of the operation
6098 -- may be literals, in which case the resulting type appears to be
6099 -- compatible with a signed integer type, when in fact it is compatible
6100 -- only with modular types. If the context itself is universal, the
6101 -- operation is illegal.
6109 Error_Msg_N
6116 then
6130 -- Check for violation of restriction No_Direct_Boolean_Operators
6131 -- if the operator was not eliminated by the Eval_Logical_Op call.
6135 then
6140 ---------------------------
6141 -- Resolve_Membership_Op --
6142 ---------------------------
6144 -- The context can only be a boolean type, and does not determine
6145 -- the arguments. Arguments should be unambiguous, but the preference
6146 -- rule for universal types applies.
6155 begin
6161 and then
6165 then
6168 -- Ada 2005 (AI-251): Give support to the following case:
6170 -- type I is interface;
6171 -- type T is tagged ...
6173 -- function Test (O : I'Class) is
6174 -- begin
6175 -- return O in T'Class.
6176 -- end Test;
6178 -- In this case we have nothing else to do; the membership test will be
6179 -- done at run-time.
6186 then
6189 else
6198 then
6204 else
6212 ------------------
6213 -- Resolve_Null --
6214 ------------------
6217 begin
6218 -- Handle restriction against anonymous null access values This
6219 -- restriction can be turned off using -gnatdh.
6221 -- Ada 2005 (AI-231): Remove restriction
6224 and then not Debug_Flag_J
6227 then
6228 -- In the common case of a call which uses an explicitly null
6229 -- value for an access parameter, give specialized error msg
6232 or else
6234 then
6235 Error_Msg_N
6238 -- Standard message for all other cases (are there any?)
6240 else
6241 Error_Msg_N
6246 -- In a distributed context, null for a remote access to subprogram
6247 -- may need to be replaced with a special record aggregate. In this
6248 -- case, return after having done the transformation.
6253 then
6257 -- The null literal takes its type from the context
6262 -----------------------
6263 -- Resolve_Op_Concat --
6264 -----------------------
6272 -- Internal procedure to resolve one operand of concatenation operator.
6273 -- The operand is either of the array type or of the component type.
6274 -- If the operand is an aggregate, and the component type is composite,
6275 -- this is ambiguous if component type has aggregates.
6277 -------------------------------
6278 -- Resolve_Concatenation_Arg --
6279 -------------------------------
6282 begin
6284 if Is_Comp
6288 then
6290 else
6298 then
6302 else
6307 else
6311 then
6313 declare
6318 begin
6323 -- Special-case the error message when the overloading
6324 -- is caused by a function that yields and array and
6325 -- can be called without parameters.
6330 Error_Msg_NE
6332 Error_Msg_NE
6336 else
6337 Error_Msg_N
6346 then
6364 else
6369 else
6376 -- Start of processing for Resolve_Op_Concat
6378 begin
6379 -- The parser folds an enormous sequence of concatenations of string
6380 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
6381 -- in the right. If the expression resolves to a predefined "&"
6382 -- operator, all is well. Otherwise, the parser's folding is wrong, so
6383 -- we give an error. See P_Simple_Expression in Par.Ch4.
6388 then
6402 -- If the operands are themselves concatenations, resolve them as such
6403 -- directly. This removes several layers of recursion and allows GNAT to
6404 -- handle larger multiple concatenations.
6409 then
6411 else
6412 Resolve_Concatenation_Arg
6419 then
6421 else
6422 Resolve_Concatenation_Arg
6432 -- If this is not a static concatenation, but the result is a
6433 -- string type (and not an array of strings) insure that static
6434 -- string operands have their subtypes properly constructed.
6438 then
6444 ----------------------
6445 -- Resolve_Op_Expon --
6446 ----------------------
6451 begin
6452 -- Catch attempts to do fixed-point exponentation with universal
6453 -- operands, which is a case where the illegality is not caught during
6454 -- normal operator analysis.
6465 then
6472 then
6476 -- We do the resolution using the base type, because intermediate values
6477 -- in expressions always are of the base type, not a subtype of it.
6489 -- Set overflow checking bit. Much cleverer code needed here eventually
6490 -- and perhaps the Resolve routines should be separated for the various
6491 -- arithmetic operations, since they will need different processing. ???
6500 --------------------
6501 -- Resolve_Op_Not --
6502 --------------------
6508 -- This function determines if the parent node is a boolean operator
6509 -- or operation (comparison op, membership test, or short circuit form)
6510 -- and the not in question is the left operand of this operation.
6511 -- Note that if the not is in parens, then false is returned.
6513 -----------------------
6514 -- Parent_Is_Boolean --
6515 -----------------------
6518 begin
6522 else
6524 when N_Op_And |
6525 N_Op_Eq |
6526 N_Op_Ge |
6527 N_Op_Gt |
6528 N_Op_Le |
6529 N_Op_Lt |
6530 N_Op_Ne |
6531 N_Op_Or |
6532 N_Op_Xor |
6533 N_In |
6534 N_Not_In |
6535 N_And_Then |
6536 N_Or_Else =>
6546 -- Start of processing for Resolve_Op_Not
6548 begin
6549 -- Predefined operations on scalar types yield the base type. On the
6550 -- other hand, logical operations on arrays yield the type of the
6551 -- arguments (and the context).
6555 else
6559 -- Straigtforward case of incorrect arguments
6566 -- Special case of probable missing parens
6570 Error_Msg_N
6573 else
6574 Error_Msg_N
6581 -- OK resolution of not
6583 else
6584 -- Warn if non-boolean types involved. This is a case like not a < b
6585 -- where a and b are modular, where we will get (not a) < b and most
6586 -- likely not (a < b) was intended.
6588 if Warn_On_Questionable_Missing_Parens
6590 and then Parent_Is_Boolean
6591 then
6603 -----------------------------
6604 -- Resolve_Operator_Symbol --
6605 -----------------------------
6607 -- Nothing to be done, all resolved already
6613 begin
6617 ----------------------------------
6618 -- Resolve_Qualified_Expression --
6619 ----------------------------------
6627 begin
6630 -- A qualified expression requires an exact match of the type,
6631 -- class-wide matching is not allowed. However, if the qualifying
6632 -- type is specific and the expression has a class-wide type, it
6633 -- may still be okay, since it can be the result of the expansion
6634 -- of a call to a dispatching function, so we also have to check
6635 -- class-wideness of the type of the expression's original node.
6638 or else
6642 then
6646 -- If the target type is unconstrained, then we reset the type of
6647 -- the result from the type of the expression. For other cases, the
6648 -- actual subtype of the expression is the target type.
6652 then
6659 -------------------
6660 -- Resolve_Range --
6661 -------------------
6667 begin
6675 -- We have to check the bounds for being within the base range as
6676 -- required for a non-static context. Normally this is automatic and
6677 -- done as part of evaluating expressions, but the N_Range node is an
6678 -- exception, since in GNAT we consider this node to be a subexpression,
6679 -- even though in Ada it is not. The circuit in Sem_Eval could check for
6680 -- this, but that would put the test on the main evaluation path for
6681 -- expressions.
6686 -- Check for an ambiguous range over character literals. This will
6687 -- happen with a membership test involving only literals.
6695 -- If bounds are static, constant-fold them, so size computations
6696 -- are identical between front-end and back-end. Do not perform this
6697 -- transformation while analyzing generic units, as type information
6698 -- would then be lost when reanalyzing the constant node in the
6699 -- instance.
6712 --------------------------
6713 -- Resolve_Real_Literal --
6714 --------------------------
6719 begin
6720 -- Special processing for fixed-point literals to make sure that the
6721 -- value is an exact multiple of small where this is required. We
6722 -- skip this for the universal real case, and also for generic types.
6728 then
6729 declare
6736 begin
6737 -- Case of literal is not an exact multiple of the Small
6741 -- For a source program literal for a decimal fixed-point
6742 -- type, this is statically illegal (RM 4.9(36)).
6747 then
6751 -- Generate a warning if literal from source
6754 and then Warn_On_Bad_Fixed_Value
6755 then
6756 Error_Msg_N
6758 N);
6761 -- Replace literal by a value that is the exact representation
6762 -- of a value of the type, i.e. a multiple of the small value,
6763 -- by truncation, since Machine_Rounds is false for all GNAT
6764 -- fixed-point types (RM 4.9(38)).
6774 -- In all cases, set the corresponding integer field
6780 -- Now replace the actual type by the expected type as usual
6786 -----------------------
6787 -- Resolve_Reference --
6788 -----------------------
6793 begin
6794 -- Replace general access with specific type
6802 -- If we are taking the reference of a volatile entity, then treat
6803 -- it as a potential modification of this entity. This is much too
6804 -- conservative, but is necessary because remove side effects can
6805 -- result in transformations of normal assignments into reference
6806 -- sequences that otherwise fail to notice the modification.
6813 --------------------------------
6814 -- Resolve_Selected_Component --
6815 --------------------------------
6830 -- Check whether this is the initialization of a component within an
6831 -- init proc (by assignment or call to another init proc). If true,
6832 -- there is no need for a discriminant check.
6834 --------------------
6835 -- Init_Component --
6836 --------------------
6839 begin
6840 return Inside_Init_Proc
6846 -- Start of processing for Resolve_Selected_Component
6848 begin
6851 -- Use the context type to select the prefix that has a selector
6852 -- of the correct name and type.
6860 else
6869 then
6876 else
6880 Error_Msg_N
6885 else
6888 -- There may be an implicit dereference. Retrieve
6889 -- designated record type.
6893 else
6899 -- Resolution chooses the new interpretation.
6900 -- Find the component with the right name.
6905 loop
6927 else
6928 -- Resolve prefix with its type
6933 -- Generate cross-reference. We needed to wait until full overloading
6934 -- resolution was complete to do this, since otherwise we can't tell if
6935 -- we are an Lvalue of not.
6939 else
6943 -- If prefix is an access type, the node will be transformed into an
6944 -- explicit dereference during expansion. The type of the node is the
6945 -- designated type of that of the prefix.
6950 else
6956 or else
6963 and then not Init_Component
6964 then
6972 -- If the prefix is a record conversion, this may be a renamed
6973 -- discriminant whose bounds differ from those of the original
6974 -- one, so we must ensure that a range check is performed.
6979 then
6983 -- Note: No Eval processing is required, because the prefix is of a
6984 -- record type, or protected type, and neither can possibly be static.
6988 -------------------
6989 -- Resolve_Shift --
6990 -------------------
6997 begin
6998 -- We do the resolution using the base type, because intermediate values
6999 -- in expressions always are of the base type, not a subtype of it.
7012 ---------------------------
7013 -- Resolve_Short_Circuit --
7014 ---------------------------
7021 begin
7032 -------------------
7033 -- Resolve_Slice --
7034 -------------------
7042 begin
7045 -- Use the context type to select the prefix that yields the
7046 -- correct array type.
7048 declare
7055 begin
7063 then
7071 else
7076 else
7087 else
7097 -- If the prefix is an access to an unconstrained array, we must use
7098 -- the actual subtype of the object to perform the index checks. The
7099 -- object denoted by the prefix is implicit in the node, so we build
7100 -- an explicit representation for it in order to compute the actual
7101 -- subtype.
7106 declare
7110 begin
7120 then
7123 -- If the name is a selected component that depends on discriminants,
7124 -- build an actual subtype for it. This can happen only when the name
7125 -- itself is overloaded; otherwise the actual subtype is created when
7126 -- the selected component is analyzed.
7129 and then Full_Analysis
7131 then
7132 declare
7135 begin
7141 -- If name was overloaded, set slice type correctly now
7145 -- If the range is specified by a subtype mark, no resolution is
7146 -- necessary. Else resolve the bounds, and apply needed checks.
7154 -- Do not apply the range check to nodes associated with the
7155 -- frontend expansion of the dispatch table. We first check
7156 -- if Ada.Tags is already loaded to void the addition of an
7157 -- undesired dependence on such run-time unit.
7159 and then
7161 or else not
7167 then
7182 ----------------------------
7183 -- Resolve_String_Literal --
7184 ----------------------------
7195 begin
7196 -- For a string appearing in a concatenation, defer creation of the
7197 -- string_literal_subtype until the end of the resolution of the
7198 -- concatenation, because the literal may be constant-folded away. This
7199 -- is a useful optimization for long concatenation expressions.
7201 -- If the string is an aggregate built for a single character (which
7202 -- happens in a non-static context) or a is null string to which special
7203 -- checks may apply, we build the subtype. Wide strings must also get a
7204 -- string subtype if they come from a one character aggregate. Strings
7205 -- generated by attributes might be static, but it is often hard to
7206 -- determine whether the enclosing context is static, so we generate
7207 -- subtypes for them as well, thus losing some rarer optimizations ???
7208 -- Same for strings that come from a static conversion.
7210 Need_Check :=
7219 -- If the resolving type is itself a string literal subtype, we
7220 -- can just reuse it, since there is no point in creating another.
7226 and then not Need_Check
7231 then
7234 -- Otherwise we must create a string literal subtype. Note that the
7235 -- whole idea of string literal subtypes is simply to avoid the need
7236 -- for building a full fledged array subtype for each literal.
7237 else
7243 or else Need_Check
7244 then
7251 then
7257 -- The validity of a null string has been checked in the
7258 -- call to Eval_String_Literal.
7263 -- Always accept string literal with component type Any_Character, which
7264 -- occurs in error situations and in comparisons of literals, both of
7265 -- which should accept all literals.
7270 -- If the type is bit-packed, then we always tranform the string literal
7271 -- into a full fledged aggregate.
7276 -- Deal with cases of Wide_Wide_String, Wide_String, and String
7278 else
7279 -- For Standard.Wide_Wide_String, or any other type whose component
7280 -- type is Standard.Wide_Wide_Character, we know that all the
7281 -- characters in the string must be acceptable, since the parser
7282 -- accepted the characters as valid character literals.
7287 -- For the case of Standard.String, or any other type whose component
7288 -- type is Standard.Character, we must make sure that there are no
7289 -- wide characters in the string, i.e. that it is entirely composed
7290 -- of characters in range of type Character.
7292 -- If the string literal is the result of a static concatenation, the
7293 -- test has already been performed on the components, and need not be
7294 -- repeated.
7298 then
7302 -- If we are out of range, post error. This is one of the
7303 -- very few places that we place the flag in the middle of
7304 -- a token, right under the offending wide character.
7306 Error_Msg
7313 -- For the case of Standard.Wide_String, or any other type whose
7314 -- component type is Standard.Wide_Character, we must make sure that
7315 -- there are no wide characters in the string, i.e. that it is
7316 -- entirely composed of characters in range of type Wide_Character.
7318 -- If the string literal is the result of a static concatenation,
7319 -- the test has already been performed on the components, and need
7320 -- not be repeated.
7324 then
7328 -- If we are out of range, post error. This is one of the
7329 -- very few places that we place the flag in the middle of
7330 -- a token, right under the offending wide character.
7332 -- This is not quite right, because characters in general
7333 -- will take more than one character position ???
7335 Error_Msg
7342 -- If the root type is not a standard character, then we will convert
7343 -- the string into an aggregate and will let the aggregate code do
7344 -- the checking. Standard Wide_Wide_Character is also OK here.
7346 else
7350 -- See if the component type of the array corresponding to the string
7351 -- has compile time known bounds. If yes we can directly check
7352 -- whether the evaluation of the string will raise constraint error.
7353 -- Otherwise we need to transform the string literal into the
7354 -- corresponding character aggregate and let the aggregate
7355 -- code do the checking.
7360 then
7361 -- Check for the case of full range, where we are definitely OK
7367 -- Here the range is not the complete base type range, so check
7369 declare
7377 begin
7380 then
7386 then
7387 Apply_Compile_Time_Constraint_Error
7399 -- If we got here we meed to transform the string literal into the
7400 -- equivalent qualified positional array aggregate. This is rather
7401 -- heavy artillery for this situation, but it is hard work to avoid.
7403 declare
7408 begin
7409 -- Build the character literals, we give them source locations that
7410 -- correspond to the string positions, which is a bit tricky given
7411 -- the possible presence of wide character escape sequences.
7425 -- Should we have a call to Skip_Wide here ???
7426 -- ??? else
7427 -- Skip_Wide (P);
7435 Expression =>
7442 -----------------------------
7443 -- Resolve_Subprogram_Info --
7444 -----------------------------
7447 begin
7451 -----------------------------
7452 -- Resolve_Type_Conversion --
7453 -----------------------------
7464 begin
7465 if not Conv_OK
7467 then
7473 -- Mixed-mode operation involving a literal. Context must be a fixed
7474 -- type which is applied to the literal subsequently.
7484 then
7485 -- Return if expression is ambiguous
7490 -- If nothing else, the available fixed type is Duration
7492 else
7496 -- Resolve the real operand with largest available precision
7500 else
7506 -- If the operand is a literal (it could be a non-static and
7507 -- illegal exponentiation) check whether the use of Duration
7508 -- is potentially inaccurate.
7513 then
7514 Error_Msg_N
7517 Rop);
7518 Error_Msg_N
7525 then
7528 else
7537 -- Note: we do the Eval_Type_Conversion call before applying the
7538 -- required checks for a subtype conversion. This is important,
7539 -- since both are prepared under certain circumstances to change
7540 -- the type conversion to a constraint error node, but in the case
7541 -- of Eval_Type_Conversion this may reflect an illegality in the
7542 -- static case, and we would miss the illegality (getting only a
7543 -- warning message), if we applied the type conversion checks first.
7547 -- Even when evaluation is not possible, we may be able to simplify
7548 -- the conversion or its expression. This needs to be done before
7549 -- applying checks, since otherwise the checks may use the original
7550 -- expression and defeat the simplifications. This is specifically
7551 -- the case for elimination of the floating-point Truncation
7552 -- attribute in float-to-int conversions.
7556 -- If after evaluation we still have a type conversion, then we
7557 -- may need to apply checks required for a subtype conversion.
7559 -- Skip these type conversion checks if universal fixed operands
7560 -- operands involved, since range checks are handled separately for
7561 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
7567 then
7571 -- Issue warning for conversion of simple object to its own type
7572 -- We have to test the original nodes, since they may have been
7573 -- rewritten by various optimizations.
7577 if Warn_On_Redundant_Constructs
7580 and then not In_Instance
7581 then
7585 -- If the node is part of a larger expression, the Target_Type
7586 -- may not be the original type of the node if the context is a
7587 -- condition. Recover original type to see if conversion is needed.
7591 then
7596 and then
7598 or else
7601 then
7603 Error_Msg_NE
7608 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
7609 -- No need to perform any interface conversion if the type of the
7610 -- expression coincides with the target type.
7613 and then Expander_Active
7615 then
7616 declare
7620 begin
7632 -- Conversion from interface type
7636 -- Ada 2005 (AI-217): Handle entities from limited views
7642 Error_Msg_N
7644 N);
7647 and then not
7650 then
7654 Error_Msg_N
7656 N);
7658 else
7662 -- Conversion to interface type
7666 -- Handle subtypes
7670 then
7674 if not Interface_Present_In_Ancestor
7677 then
7680 -- The static analysis is not enough to know if the
7681 -- interface is implemented or not. Hence we must pass
7682 -- the work to the expander to generate code to evaluate
7683 -- the conversion at run-time.
7687 else
7690 Error_Msg_N
7695 else
7703 ----------------------
7704 -- Resolve_Unary_Op --
7705 ----------------------
7714 begin
7715 -- Deal with intrinsic unary operators
7721 then
7726 -- Deal with universal cases
7729 or else
7731 then
7738 -- Generate warning for expressions like abs (x mod 2)
7740 if Warn_On_Redundant_Constructs
7742 then
7746 Error_Msg_N
7751 -- Deal with reference generation
7757 -- Set overflow checking bit. Much cleverer code needed here eventually
7758 -- and perhaps the Resolve routines should be separated for the various
7759 -- arithmetic operations, since they will need different processing ???
7767 -- Generate warning for expressions like -5 mod 3 for integers. No
7768 -- need to worry in the floating-point case, since parens do not affect
7769 -- the result so there is no point in giving in a warning.
7771 declare
7780 begin
7781 if Warn_On_Questionable_Missing_Parens
7785 then
7788 -- We are looking for cases where the right operand is not
7789 -- parenthesized, and is a bianry operator, multiply, divide, or
7790 -- mod. These are the cases where the grouping can affect results.
7794 or else
7796 or else
7798 then
7799 -- For mod, we always give the warning, since the value is
7800 -- affected by the parenthesization (e.g. (-5) mod 315 /=
7801 -- (5 mod 315)). But for the other cases, the only concern is
7802 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
7803 -- overflows, but (-2) * 64 does not). So we try to give the
7804 -- message only when overflow is possible.
7808 then
7813 else
7819 else
7823 -- Note that the test below is deliberately excluding
7824 -- the largest negative number, since that is a potentially
7825 -- troublesome case (e.g. -2 * x, where the result is the
7826 -- largest negative integer has an overflow with 2 * x).
7833 -- For the multiplication case, the only case we have to worry
7834 -- about is when (-a)*b is exactly the largest negative number
7835 -- so that -(a*b) can cause overflow. This can only happen if
7836 -- a is a power of 2, and more generally if any operand is a
7837 -- constant that is not a power of 2, then the parentheses
7838 -- cannot affect whether overflow occurs. We only bother to
7839 -- test the left most operand
7841 -- Loop looking at left operands for one that has known value
7848 -- Operand value of 0 or 1 skips warning
7853 -- Otherwise check power of 2, if power of 2, warn, if
7854 -- anything else, skip warning.
7856 else
7860 else
7869 -- Keep looking at left operands
7874 -- For rem or "/" we can only have a problematic situation
7875 -- if the divisor has a value of minus one or one. Otherwise
7876 -- overflow is impossible (divisor > 1) or we have a case of
7877 -- division by zero in any case.
7880 or else
7884 then
7888 -- If we fall through warning should be issued
7890 Error_Msg_N
7897 ----------------------------------
7898 -- Resolve_Unchecked_Expression --
7899 ----------------------------------
7901 procedure Resolve_Unchecked_Expression
7904 is
7905 begin
7910 ---------------------------------------
7911 -- Resolve_Unchecked_Type_Conversion --
7912 ---------------------------------------
7914 procedure Resolve_Unchecked_Type_Conversion
7917 is
7923 begin
7924 -- Resolve operand using its own type
7931 ------------------------------
7932 -- Rewrite_Operator_As_Call --
7933 ------------------------------
7940 begin
7947 New_N :=
7958 ------------------------------
7959 -- Rewrite_Renamed_Operator --
7960 ------------------------------
7962 procedure Rewrite_Renamed_Operator
7966 is
7971 begin
7972 -- Rewrite the operator node using the real operator, not its
7973 -- renaming. Exclude user-defined intrinsic operations of the same
7974 -- name, which are treated separately and rewritten as calls.
7978 then
7985 -- Indicate that both the original entity and its renaming are
7986 -- referenced at this point.
7997 -- If the context type is private, add the appropriate conversions
7998 -- so that the operator is applied to the full view. This is done
7999 -- in the routines that resolve intrinsic operators,
8003 then
8005 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
8006 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
8019 then
8020 -- Operator renames a user-defined operator of the same name. Use
8021 -- the original operator in the node, which is the one that Gigi
8022 -- knows about.
8029 -----------------------
8030 -- Set_Slice_Subtype --
8031 -----------------------
8033 -- Build an implicit subtype declaration to represent the type delivered
8034 -- by the slice. This is an abbreviated version of an array subtype. We
8035 -- define an index subtype for the slice, using either the subtype name
8036 -- or the discrete range of the slice. To be consistent with index usage
8037 -- elsewhere, we create a list header to hold the single index. This list
8038 -- is not otherwise attached to the syntax tree.
8049 begin
8053 else
8054 -- We force the evaluation of a range. This is definitely needed in
8055 -- the renamed case, and seems safer to do unconditionally. Note in
8056 -- any case that since we will create and insert an Itype referring
8057 -- to this range, we must make sure any side effect removal actions
8058 -- are inserted before the Itype definition.
8088 -- The Etype of the existing Slice node is reset to this slice subtype.
8089 -- Its bounds are obtained from its first index.
8093 -- In the packed case, this must be immediately frozen
8095 -- Couldn't we always freeze here??? and if we did, then the above
8096 -- call to Check_Compile_Time_Size could be eliminated, which would
8097 -- be nice, because then that routine could be made private to Freeze.
8105 --------------------------------
8106 -- Set_String_Literal_Subtype --
8107 --------------------------------
8115 begin
8129 -- The low bound is set from the low bound of the corresponding
8130 -- index type. Note that we do not store the high bound in the
8131 -- string literal subtype, but it can be deduced if necessary
8132 -- from the length and the low bound.
8136 else
8137 Set_String_Literal_Low_Bound
8141 -- Build bona fide subtype for the string, and wrap it in an
8142 -- unchecked conversion, because the backend expects the
8143 -- String_Literal_Subtype to have a static lower bound.
8145 declare
8151 Right_Opnd =>
8159 begin
8160 Index_Subtype :=
8191 ------------------------------
8192 -- Simplify_Type_Conversion --
8193 ------------------------------
8196 begin
8198 declare
8203 begin
8205 and then
8212 -- Special processing required if the conversion is the expression
8213 -- of a Truncation attribute reference. In this case we replace:
8215 -- ityp (ftyp'Truncation (x))
8217 -- by
8219 -- ityp (x)
8221 -- with the Float_Truncate flag set, which is more efficient
8223 then
8232 -----------------------------
8233 -- Unique_Fixed_Point_Type --
8234 -----------------------------
8243 -- If true ambiguity, give details
8245 -----------------------
8246 -- Fixed_Point_Error --
8247 -----------------------
8250 begin
8256 -- Start of processing for Unique_Fixed_Point_Type
8258 begin
8259 -- The operations on Duration are visible, so Duration is always a
8260 -- possible interpretation.
8264 -- Look for fixed-point types in enclosing scopes
8273 then
8275 Fixed_Point_Error;
8277 else
8288 -- Look for visible fixed type declarations in the context
8300 then
8302 Fixed_Point_Error;
8304 else
8319 else
8326 ----------------------
8327 -- Valid_Conversion --
8328 ----------------------
8330 function Valid_Conversion
8334 is
8338 function Conversion_Check
8341 -- Little routine to post Msg if Valid is False, returns Valid value
8343 function Valid_Tagged_Conversion
8346 -- Specifically test for validity of tagged conversions
8349 -- Check index and component conformance, and accessibility levels
8350 -- if the component types are anonymous access types (Ada 2005)
8352 ----------------------
8353 -- Conversion_Check --
8354 ----------------------
8356 function Conversion_Check
8359 is
8360 begin
8368 ----------------------------
8369 -- Valid_Array_Conversion --
8370 ----------------------------
8373 is
8388 begin
8389 -- Error if wrong number of dimensions
8391 if
8393 then
8394 Error_Msg_N
8398 -- Number of dimensions matches
8400 else
8401 -- Loop through indexes of the two arrays
8409 -- Error if index types are incompatible
8415 then
8416 Error_Msg_N
8418 Operand);
8426 -- If component types have same base type, all set
8431 -- Here if base types of components are not the same. The only
8432 -- time this is allowed is if we have anonymous access types.
8434 -- The conversion of arrays of anonymous access types can lead
8435 -- to dangling pointers. AI-392 formalizes the accessibility
8436 -- checks that must be applied to such conversions to prevent
8437 -- out-of-scope references.
8439 elsif
8441 or else
8444 and then
8446 then
8449 then
8454 Operand);
8461 -- Conversion not allowed because of accessibility levels
8463 else
8468 else
8472 -- All other cases where component base types do not match
8474 else
8475 Error_Msg_N
8477 Operand);
8481 -- Check that component subtypes statically match
8485 or else not Subtypes_Statically_Match
8487 then
8488 Error_Msg_N
8497 -----------------------------
8498 -- Valid_Tagged_Conversion --
8499 -----------------------------
8501 function Valid_Tagged_Conversion
8504 is
8505 begin
8506 -- Upward conversions are allowed (RM 4.6(22))
8510 then
8513 -- Downward conversion are allowed if the operand is class-wide
8514 -- (RM 4.6(23)).
8518 then
8523 then
8524 return
8528 -- Ada 2005 (AI-251): The conversion to/from interface types is
8529 -- always valid
8534 -- If the operand is a class-wide type obtained through a limited_
8535 -- with clause, and the context includes the non-limited view, use
8536 -- it to determine whether the conversion is legal.
8542 then
8547 then
8550 else
8551 Error_Msg_NE
8558 -- Start of processing for Valid_Conversion
8560 begin
8564 declare
8571 begin
8572 -- Remove procedure calls, which syntactically cannot appear
8573 -- in this context, but which cannot be removed by type checking,
8574 -- because the context does not impose a type.
8576 -- When compiling for VMS, spurious ambiguities can be produced
8577 -- when arithmetic operations have a literal operand and return
8578 -- System.Address or a descendant of it. These ambiguities are
8579 -- otherwise resolved by the context, but for conversions there
8580 -- is no context type and the removal of the spurious operations
8581 -- must be done explicitly here.
8583 -- The node may be labelled overloaded, but still contain only
8584 -- one interpretation because others were discarded in previous
8585 -- filters. If this is the case, retain the single interpretation
8586 -- if legal.
8594 then
8595 -- More than one candidate interpretation is available
8605 then
8646 -- Numeric types
8650 -- A universal fixed expression can be converted to any numeric type
8655 -- Also no need to check when in an instance or inlined body, because
8656 -- the legality has been established when the template was analyzed.
8657 -- Furthermore, numeric conversions may occur where only a private
8658 -- view of the operand type is visible at the instanciation point.
8659 -- This results in a spurious error if we check that the operand type
8660 -- is a numeric type.
8662 -- Note: in a previous version of this unit, the following tests were
8663 -- applied only for generated code (Comes_From_Source set to False),
8664 -- but in fact the test is required for source code as well, since
8665 -- this situation can arise in source code.
8670 -- Otherwise we need the conversion check
8672 else
8673 return Conversion_Check
8678 -- Array types
8684 then
8685 Error_Msg_N
8688 else
8692 -- Ada 2005 (AI-251): Anonymous access types where target references an
8693 -- interface type.
8696 or else
8699 then
8700 -- Check the static accessibility rule of 4.6(17). Note that the
8701 -- check is not enforced when within an instance body, since the RM
8702 -- requires such cases to be caught at run time.
8707 then
8708 -- In an instance, this is a run-time check, but one we know
8709 -- will fail, so generate an appropriate warning. The raise
8710 -- will be generated by Expand_N_Type_Conversion.
8713 Error_Msg_N
8715 Operand);
8716 Error_Msg_N
8718 else
8719 Error_Msg_N
8721 Operand);
8725 -- Special accessibility checks are needed in the case of access
8726 -- discriminants declared for a limited type.
8730 then
8731 -- When the operand is a selected access discriminant the check
8732 -- needs to be made against the level of the object denoted by
8733 -- the prefix of the selected name. (Object_Access_Level
8734 -- handles checking the prefix of the operand for this case.)
8739 then
8740 -- In an instance, this is a run-time check, but one we
8741 -- know will fail, so generate an appropriate warning.
8742 -- The raise will be generated by Expand_N_Type_Conversion.
8745 Error_Msg_N
8748 Error_Msg_N
8750 else
8751 Error_Msg_N
8758 -- The case of a reference to an access discriminant from
8759 -- within a limited type declaration (which will appear as
8760 -- a discriminal) is always illegal because the level of the
8761 -- discriminant is considered to be deeper than any (namable)
8762 -- access type.
8769 then
8770 Error_Msg_N
8772 Operand);
8780 -- General and anonymous access types
8784 and then
8785 Conversion_Check
8788 E_Access_Subprogram_Type
8790 E_Access_Protected_Subprogram_Type,
8792 then
8795 then
8796 Error_Msg_N
8801 -- Check the static accessibility rule of 4.6(17). Note that the
8802 -- check is not enforced when within an instance body, since the RM
8803 -- requires such cases to be caught at run time.
8807 then
8810 then
8811 -- In an instance, this is a run-time check, but one we
8812 -- know will fail, so generate an appropriate warning.
8813 -- The raise will be generated by Expand_N_Type_Conversion.
8816 Error_Msg_N
8818 Operand);
8819 Error_Msg_N
8822 else
8823 -- Avoid generation of spurious error message
8826 Error_Msg_N
8828 Operand);
8834 -- Special accessibility checks are needed in the case of access
8835 -- discriminants declared for a limited type.
8839 then
8841 -- When the operand is a selected access discriminant the check
8842 -- needs to be made against the level of the object denoted by
8843 -- the prefix of the selected name. (Object_Access_Level
8844 -- handles checking the prefix of the operand for this case.)
8849 then
8850 -- In an instance, this is a run-time check, but one we
8851 -- know will fail, so generate an appropriate warning.
8852 -- The raise will be generated by Expand_N_Type_Conversion.
8855 Error_Msg_N
8858 Error_Msg_N
8860 Operand);
8862 else
8863 Error_Msg_N
8870 -- The case of a reference to an access discriminant from
8871 -- within a limited type declaration (which will appear as
8872 -- a discriminal) is always illegal because the level of the
8873 -- discriminant is considered to be deeper than any (namable)
8874 -- access type.
8880 then
8881 Error_Msg_N
8883 Operand);
8889 declare
8891 -- Helper function to handle limited views
8893 --------------------------
8894 -- Full_Designated_Type --
8895 --------------------------
8899 begin
8903 then
8905 else
8916 begin
8920 else
8922 Error_Msg_NE
8927 -- Ada 2005 AI-384: legality rule is symmetric in both
8928 -- designated types. The conversion is legal (with possible
8929 -- constraint check) if either designated type is
8930 -- unconstrained.
8933 or else
8935 and then
8938 then
8941 else
8942 Error_Msg_NE
8950 -- Subprogram access types
8953 or else
8956 then
8957 if
8959 then
8960 Error_Msg_N
8962 Operand);
8963 Error_Msg_N
8966 Operand);
8970 then
8971 Error_Msg_NE
8977 -- Check that the designated types are subtype conformant
8983 -- Check the static accessibility rule of 4.6(20)
8987 then
8988 Error_Msg_N
8990 Operand);
8992 -- Check that if the operand type is declared in a generic body,
8993 -- then the target type must be declared within that same body
8994 -- (enforces last sentence of 4.6(20)).
8997 declare
9003 begin
9010 Error_Msg_N
9019 -- Remote subprogram access types
9023 then
9024 -- It is valid to convert from one RAS type to another provided
9025 -- that their specification statically match.
9027 Check_Subtype_Conformant
9030 Old_Id =>
9032 Err_Loc =>
9033 N);
9036 -- If both are tagged types, check legality of view conversions
9040 then
9043 -- Types derived from the same root type are convertible
9048 -- In an instance or an inlined body, there may be inconsistent
9049 -- views of the same type, or of types derived from a common root.
9052 and then
9055 then
9058 -- Special check for common access type error case
9062 then
9068 else