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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) 1992-2015, Free Software Foundation, Inc. --
10 -- --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
20 -- --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
23 -- --
24 ------------------------------------------------------------------------------
86 -----------------------
87 -- Local Subprograms --
88 -----------------------
90 -- Second pass (top-down) type checking and overload resolution procedures
91 -- Typ is the type required by context. These procedures propagate the
92 -- type information recursively to the descendants of N. If the node is not
93 -- overloaded, its Etype is established in the first pass. If overloaded,
94 -- the Resolve routines set the correct type. For arithmetic operators, the
95 -- Etype is the base type of the context.
97 -- Note that Resolve_Attribute is separated off in Sem_Attr
100 -- Enforce the restrictions on the use of discriminants when constraining
101 -- a component of a discriminated type (record or concurrent type).
104 -- Given a node for an operator associated with type T, check that the
105 -- operator is visible. Operators all of whose operands are universal must
106 -- be checked for visibility during resolution because their type is not
107 -- determinable based on their operands.
109 procedure Check_Fully_Declared_Prefix
112 -- Check that the type of the prefix of a dereference is not incomplete
115 -- Given a call node, N, which is known to occur immediately within the
116 -- subprogram being called, determines whether it is a detectable case of
117 -- an infinite recursion, and if so, outputs appropriate messages. Returns
118 -- True if an infinite recursion is detected, and False otherwise.
121 -- If the type of the object being initialized uses the secondary stack
122 -- directly or indirectly, create a transient scope for the call to the
123 -- init proc. This is because we do not create transient scopes for the
124 -- initialization of individual components within the init proc itself.
125 -- Could be optimized away perhaps?
128 -- N is the node for a logical operator. If the operator is predefined, and
129 -- the root type of the operands is Standard.Boolean, then a check is made
130 -- for restriction No_Direct_Boolean_Operators. This procedure also handles
131 -- the style check for Style_Check_Boolean_And_Or.
134 -- N is either an indexed component or a selected component. This function
135 -- returns true if the prefix refers to an object that has an address
136 -- clause (the case in which we may want to issue a warning).
139 -- Determine whether E is an access type declared by an access declaration,
140 -- and not an (anonymous) allocator type.
143 -- Utility to check whether the entity for an operator is a predefined
144 -- operator, in which case the expression is left as an operator in the
145 -- tree (else it is rewritten into a call). An instance of an intrinsic
146 -- conversion operation may be given an operator name, but is not treated
147 -- like an operator. Note that an operator that is an imported back-end
148 -- builtin has convention Intrinsic, but is expected to be rewritten into
149 -- a call, so such an operator is not treated as predefined by this
150 -- predicate.
153 -- If a default expression in entry call N depends on the discriminants
154 -- of the task, it must be replaced with a reference to the discriminant
155 -- of the task being called.
157 procedure Resolve_Op_Concat_Arg
162 -- Internal procedure for Resolve_Op_Concat to resolve one operand of
163 -- concatenation operator. The operand is either of the array type or of
164 -- the component type. If the operand is an aggregate, and the component
165 -- type is composite, this is ambiguous if component type has aggregates.
168 -- Does the first part of the work of Resolve_Op_Concat
171 -- Does the "rest" of the work of Resolve_Op_Concat, after the left operand
172 -- has been resolved. See Resolve_Op_Concat for details.
210 function Operator_Kind
213 -- Utility to map the name of an operator into the corresponding Node. Used
214 -- by other node rewriting procedures.
217 -- Resolve actuals of call, and add default expressions for missing ones.
218 -- N is the Node_Id for the subprogram call, and Nam is the entity of the
219 -- called subprogram.
222 -- Called from Resolve_Call, when the prefix denotes an entry or element
223 -- of entry family. Actuals are resolved as for subprograms, and the node
224 -- is rebuilt as an entry call. Also called for protected operations. Typ
225 -- is the context type, which is used when the operation is a protected
226 -- function with no arguments, and the return value is indexed.
229 -- A call to a user-defined intrinsic operator is rewritten as a call to
230 -- the corresponding predefined operator, with suitable conversions. Note
231 -- that this applies only for intrinsic operators that denote predefined
232 -- operators, not ones that are intrinsic imports of back-end builtins.
235 -- Ditto, for arithmetic unary operators
238 -- If an operator node resolves to a call to a user-defined operator,
239 -- rewrite the node as a function call.
241 procedure Make_Call_Into_Operator
245 -- Inverse transformation: if an operator is given in functional notation,
246 -- then after resolving the node, transform into an operator node, so that
247 -- operands are resolved properly. Recall that predefined operators do not
248 -- have a full signature and special resolution rules apply.
250 procedure Rewrite_Renamed_Operator
254 -- An operator can rename another, e.g. in an instantiation. In that
255 -- case, the proper operator node must be constructed and resolved.
258 -- The String_Literal_Subtype is built for all strings that are not
259 -- operands of a static concatenation operation. If the argument is not
260 -- a N_String_Literal node, then the call has no effect.
263 -- Build subtype of array type, with the range specified by the slice
266 -- Called after N has been resolved and evaluated, but before range checks
267 -- have been applied. Currently simplifies a combination of floating-point
268 -- to integer conversion and Rounding or Truncation attribute.
271 -- A universal_fixed expression in an universal context is unambiguous if
272 -- there is only one applicable fixed point type. Determining whether there
273 -- is only one requires a search over all visible entities, and happens
274 -- only in very pathological cases (see 6115-006).
276 -------------------------
277 -- Ambiguous_Character --
278 -------------------------
283 begin
287 -- First the ones in Standard
292 -- Include Wide_Wide_Character in Ada 2005 mode
298 -- Now any other types that match
308 -------------------------
309 -- Analyze_And_Resolve --
310 -------------------------
313 begin
319 begin
324 -- Versions with check(s) suppressed
326 procedure Analyze_And_Resolve
330 is
333 begin
335 declare
337 begin
343 else
344 declare
346 begin
354 and then Scope_Is_Transient
355 then
356 -- This can only happen if a transient scope was created for an inner
357 -- expression, which will be removed upon completion of the analysis
358 -- of an enclosing construct. The transient scope must have the
359 -- suppress status of the enclosing environment, not of this Analyze
360 -- call.
363 Scope_Suppress;
367 procedure Analyze_And_Resolve
370 is
373 begin
375 declare
377 begin
383 else
384 declare
386 begin
395 Scope_Suppress;
399 ----------------------------
400 -- Check_Discriminant_Use --
401 ----------------------------
409 begin
410 -- Any use in a spec-expression is legal
417 -- Discriminant cannot be used to constrain a scalar type
424 then
429 -- The following check catches the unusual case where a
430 -- discriminant appears within an index constraint that is part
431 -- of a larger expression within a constraint on a component,
432 -- e.g. "C : Int range 1 .. F (new A(1 .. D))". For now we only
433 -- check case of record components, and note that a similar check
434 -- should also apply in the case of discriminant constraints
435 -- below. ???
437 -- Note that the check for N_Subtype_Declaration below is to
438 -- detect the valid use of discriminants in the constraints of a
439 -- subtype declaration when this subtype declaration appears
440 -- inside the scope of a record type (which is syntactically
441 -- illegal, but which may be created as part of derived type
442 -- processing for records). See Sem_Ch3.Build_Derived_Record_Type
443 -- for more info.
447 and then not
449 and then
451 N_Subtype_Declaration)
453 then
454 Error_Msg_N
459 -- Detect a common error:
461 -- type R (D : Positive := 100) is record
462 -- Name : String (1 .. D);
463 -- end record;
465 -- The default value causes an object of type R to be allocated
466 -- with room for Positive'Last characters. The RM does not mandate
467 -- the allocation of the maximum size, but that is what GNAT does
468 -- so we should warn the programmer that there is a problem.
477 -- Return True if type T has a large enough range that any
478 -- array whose index type covered the whole range of the type
479 -- would likely raise Storage_Error.
481 ------------------------
482 -- Large_Storage_Type --
483 ------------------------
486 begin
487 -- The type is considered large if its bounds are known at
488 -- compile time and if it requires at least as many bits as
489 -- a Positive to store the possible values.
493 and then
498 -- Start of processing for Check_Large
500 begin
501 -- Check that the Disc has a large range
507 -- If the enclosing type is limited, we allocate only the
508 -- default value, not the maximum, and there is no need for
509 -- a warning.
515 -- Check that it is the high bound
519 then
523 -- Check the array allows a large range at this bound. First
524 -- find the array
538 -- Next, find the dimension
546 loop
555 -- Now, check the dimension has a large range
561 -- Warn about the danger
563 Error_Msg_N
573 -- Legal case is in index or discriminant constraint
576 N_Discriminant_Association)
577 then
579 Error_Msg_N
584 then
585 Error_Msg_N
591 -- Otherwise, context is an expression. It should not be within (i.e. a
592 -- subexpression of) a constraint for a component.
594 else
598 N_Subtype_Indication,
599 N_Entry_Declaration)
600 loop
606 -- If the discriminant is used in an expression that is a bound of a
607 -- scalar type, an Itype is created and the bounds are attached to
608 -- its range, not to the original subtype indication. Such use is of
609 -- course a double fault.
613 N_Derived_Type_Definition)
616 -- The constraint itself may be given by a subtype indication,
617 -- rather than by a more common discrete range.
620 and then
624 then
625 Error_Msg_N
631 --------------------------------
632 -- Check_For_Visible_Operator --
633 --------------------------------
636 begin
638 Error_Msg_NE -- CODEFIX
640 Error_Msg_N -- CODEFIX
645 ----------------------------------
646 -- Check_Fully_Declared_Prefix --
647 ----------------------------------
649 procedure Check_Fully_Declared_Prefix
652 is
653 begin
654 -- Check that the designated type of the prefix of a dereference is
655 -- not an incomplete type. This cannot be done unconditionally, because
656 -- dereferences of private types are legal in default expressions. This
657 -- case is taken care of in Check_Fully_Declared, called below. There
658 -- are also 2005 cases where it is legal for the prefix to be unfrozen.
660 -- This consideration also applies to similar checks for allocators,
661 -- qualified expressions, and type conversions.
663 -- An additional exception concerns other per-object expressions that
664 -- are not directly related to component declarations, in particular
665 -- representation pragmas for tasks. These will be per-object
666 -- expressions if they depend on discriminants or some global entity.
667 -- If the task has access discriminants, the designated type may be
668 -- incomplete at the point the expression is resolved. This resolution
669 -- takes place within the body of the initialization procedure, where
670 -- the discriminant is replaced by its discriminal.
674 then
677 -- Ada 2005 (AI-326): Tagged incomplete types allowed. The wrong usages
678 -- are handled by Analyze_Access_Attribute, Analyze_Assignment,
679 -- Analyze_Object_Renaming, and Freeze_Entity.
685 E_Incomplete_Type
687 then
689 else
694 ------------------------------
695 -- Check_Infinite_Recursion --
696 ------------------------------
703 -- Check whether list of actuals is identical to list of formals of
704 -- called function (which is also the enclosing scope).
706 ------------------------
707 -- Same_Argument_List --
708 ------------------------
715 begin
718 else
736 -- Start of processing for Check_Infinite_Recursion
738 begin
739 -- Special case, if this is a procedure call and is a call to the
740 -- current procedure with the same argument list, then this is for
741 -- sure an infinite recursion and we insert a call to raise SE.
745 and then Same_Argument_List
746 then
747 declare
749 begin
753 then
765 -- If not that special case, search up tree, quitting if we reach a
766 -- construct (e.g. a conditional) that tells us that this is not a
767 -- case for an infinite recursion warning.
770 loop
773 -- If no parent, then we were not inside a subprogram, this can for
774 -- example happen when processing certain pragmas in a spec. Just
775 -- return False in this case.
781 -- Done if we get to subprogram body, this is definitely an infinite
782 -- recursion case if we did not find anything to stop us.
786 -- If appearing in conditional, result is false
789 N_And_Then,
790 N_Case_Expression,
791 N_Case_Statement,
792 N_If_Expression,
793 N_If_Statement)
794 then
799 then
800 -- If the call is the expression of a return statement and the
801 -- actuals are identical to the formals, it's worth a warning.
802 -- However, we skip this if there is an immediately preceding
803 -- raise statement, since the call is never executed.
805 -- Furthermore, this corresponds to a common idiom:
807 -- function F (L : Thing) return Boolean is
808 -- begin
809 -- raise Program_Error;
810 -- return F (L);
811 -- end F;
813 -- for generating a stub function
816 and then Same_Argument_List
817 then
820 -- OK, return statement is in a statement list, look for raise
822 declare
825 begin
826 -- Skip past N_Freeze_Entity nodes generated by expansion
831 loop
835 -- If no raise statement, give warning. We look at the
836 -- original node, because in the case of "raise ... with
837 -- ...", the node has been transformed into a call.
840 and then
848 else
860 -------------------------------
861 -- Check_Initialization_Call --
862 -------------------------------
868 -- Check whether the creation of an object of the type will involve
869 -- use of the secondary stack. If T is a record type, this is true
870 -- if the expression for some component uses the secondary stack, e.g.
871 -- through a call to a function that returns an unconstrained value.
872 -- False if T is controlled, because cleanups occur elsewhere.
874 -------------
875 -- Uses_SS --
876 -------------
883 begin
884 -- Normally we want to use the underlying type, but if it's not set
885 -- then continue with T.
902 then
903 -- The expression for a dynamic component may be rewritten
904 -- as a dereference, so retrieve original node.
908 -- Return True if the expression is a call to a function
909 -- (including an attribute function such as Image, or a
910 -- user-defined operator) with a result that requires a
911 -- transient scope.
918 then
931 else
936 -- Start of processing for Check_Initialization_Call
938 begin
939 -- Establish a transient scope if the type needs it
946 ---------------------------------------
947 -- Check_No_Direct_Boolean_Operators --
948 ---------------------------------------
951 begin
954 then
955 -- Restriction only applies to original source code
962 -- Do style check (but skip if in instance, error is on template)
971 ------------------------------
972 -- Check_Parameterless_Call --
973 ------------------------------
979 -- If the prefix is of an access_to_subprogram type, the node must be
980 -- rewritten as a call. Ditto if the prefix is overloaded and all its
981 -- interpretations are access to subprograms.
983 ---------------------------
984 -- Prefix_Is_Access_Subp --
985 ---------------------------
991 begin
992 -- If the context is an attribute reference that can apply to
993 -- functions, this is never a parameterless call (RM 4.1.4(6)).
997 Name_Code_Address,
998 Name_Access)
999 then
1004 return
1007 else
1012 then
1023 -- Start of processing for Check_Parameterless_Call
1025 begin
1026 -- Defend against junk stuff if errors already detected
1033 then
1040 -- If the context expects a value, and the name is a procedure, this is
1041 -- most likely a missing 'Access. Don't try to resolve the parameterless
1042 -- call, error will be caught when the outer call is analyzed.
1047 and then
1049 N_Function_Call,
1050 N_Procedure_Call_Statement)
1051 then
1055 -- Rewrite as call if overloadable entity that is (or could be, in the
1056 -- overloaded case) a function call. If we know for sure that the entity
1057 -- is an enumeration literal, we do not rewrite it.
1059 -- If the entity is the name of an operator, it cannot be a call because
1060 -- operators cannot have default parameters. In this case, this must be
1061 -- a string whose contents coincide with an operator name. Set the kind
1062 -- of the node appropriately.
1070 -- Rewrite as call if it is an explicit dereference of an expression of
1071 -- a subprogram access type, and the subprogram type is not that of a
1072 -- procedure or entry.
1074 or else
1077 -- Rewrite as call if it is a selected component which is a function,
1078 -- this is the case of a call to a protected function (which may be
1079 -- overloaded with other protected operations).
1081 or else
1084 or else
1086 E_Procedure)
1089 -- If one of the above three conditions is met, rewrite as call. Apply
1090 -- the rewriting only once.
1092 then
1095 then
1097 -- This may be a prefixed call that was not fully analyzed, e.g.
1098 -- an actual in an instance.
1103 then
1111 -- The node is the name of the parameterless call. Preserve its
1112 -- descendants, which may be complex expressions.
1116 -- If overloaded, overload set belongs to new copy
1120 -- Change node to parameterless function call (note that the
1121 -- Parameter_Associations associations field is left set to Empty,
1122 -- its normal default value since there are no parameters)
1140 --------------------------------
1141 -- Is_Atomic_Ref_With_Address --
1142 --------------------------------
1147 begin
1151 else
1152 declare
1155 begin
1163 -----------------------------
1164 -- Is_Definite_Access_Type --
1165 -----------------------------
1169 begin
1175 ----------------------
1176 -- Is_Predefined_Op --
1177 ----------------------
1180 begin
1181 -- Predefined operators are intrinsic subprograms
1187 -- A call to a back-end builtin is never a predefined operator
1198 -----------------------------
1199 -- Make_Call_Into_Operator --
1200 -----------------------------
1202 procedure Make_Call_Into_Operator
1206 is
1221 -- If the operand is not universal, and the operator is given by an
1222 -- expanded name, verify that the operand has an interpretation with a
1223 -- type defined in the given scope of the operator.
1226 -- Find a type of the given class in package Pack that contains the
1227 -- operator.
1229 ---------------------------
1230 -- Operand_Type_In_Scope --
1231 ---------------------------
1238 begin
1242 else
1256 ---------------
1257 -- Type_In_P --
1258 ---------------
1264 -- Verify that node is not part of the type declaration for the
1265 -- candidate type, which would otherwise be invisible.
1267 -------------
1268 -- In_Decl --
1269 -------------
1275 begin
1284 else
1287 loop
1290 else
1299 -- Start of processing for Type_In_P
1301 begin
1302 -- If the context type is declared in the prefix package, this is the
1303 -- desired base type.
1308 else
1322 -- Start of processing for Make_Call_Into_Operator
1324 begin
1327 -- Binary operator
1337 -- Unary operator
1339 else
1345 -- If the operator is denoted by an expanded name, and the prefix is
1346 -- not Standard, but the operator is a predefined one whose scope is
1347 -- Standard, then this is an implicit_operator, inserted as an
1348 -- interpretation by the procedure of the same name. This procedure
1349 -- overestimates the presence of implicit operators, because it does
1350 -- not examine the type of the operands. Verify now that the operand
1351 -- type appears in the given scope. If right operand is universal,
1352 -- check the other operand. In the case of concatenation, either
1353 -- argument can be the component type, so check the type of the result.
1354 -- If both arguments are literals, look for a type of the right kind
1355 -- defined in the given scope. This elaborate nonsense is brought to
1356 -- you courtesy of b33302a. The type itself must be frozen, so we must
1357 -- find the type of the proper class in the given scope.
1359 -- A final wrinkle is the multiplication operator for fixed point types,
1360 -- which is defined in Standard only, and not in the scope of the
1361 -- fixed point type itself.
1366 -- If this is a package renaming, get renamed entity, which will be
1367 -- the scope of the operands if operaton is type-correct.
1373 -- If the entity being called is defined in the given package, it is
1374 -- a renaming of a predefined operator, and known to be legal.
1378 then
1381 -- Visibility does not need to be checked in an instance: if the
1382 -- operator was not visible in the generic it has been diagnosed
1383 -- already, else there is an implicit copy of it in the instance.
1391 then
1396 -- Ada 2005 AI-420: Predefined equality on Universal_Access is
1397 -- available.
1402 then
1405 else
1414 and then Is_Binary
1416 then
1422 -- Verify that the scope contains a type that corresponds to
1423 -- the given literal. Optimize the case where Pack is Standard.
1445 else
1454 else
1463 then
1466 -- If the type is defined elsewhere, and the operator is not
1467 -- defined in the given scope (by a renaming declaration, e.g.)
1468 -- then this is an error as well. If an extension of System is
1469 -- present, and the type may be defined there, Pack must be
1470 -- System itself.
1477 then
1480 else
1486 then
1493 Error_Msg_NE
1498 -- Detect a mismatch between the context type and the result type
1499 -- in the named package, which is otherwise not detected if the
1500 -- operands are universal. Check is only needed if source entity is
1501 -- an operator, not a function that renames an operator.
1508 and then not In_Instance
1509 then
1512 then
1513 -- Already checked above
1517 -- Operator may be defined in an extension of System
1521 then
1524 else
1525 -- Could we use Wrong_Type here??? (this would require setting
1526 -- Etype (N) to the actual type found where Typ was expected).
1537 else
1541 -- If this is a call to a function that renames a predefined equality,
1542 -- the renaming declaration provides a type that must be used to
1543 -- resolve the operands. This must be done now because resolution of
1544 -- the equality node will not resolve any remaining ambiguity, and it
1545 -- assumes that the first operand is not overloaded.
1550 then
1558 -- Do rewrite setting Comes_From_Source on the result if the original
1559 -- call came from source. Although it is not strictly the case that the
1560 -- operator as such comes from the source, logically it corresponds
1561 -- exactly to the function call in the source, so it should be marked
1562 -- this way (e.g. to make sure that validity checks work fine).
1564 declare
1566 begin
1571 -- If this is an arithmetic operator and the result type is private,
1572 -- the operands and the result must be wrapped in conversion to
1573 -- expose the underlying numeric type and expand the proper checks,
1574 -- e.g. on division.
1578 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
1579 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
1588 else
1592 -- If in ASIS_Mode, propagate operand types to original actuals of
1593 -- function call, which would otherwise not be fully resolved. If
1594 -- the call has already been constant-folded, nothing to do. We
1595 -- relocate the operand nodes rather than copy them, to preserve
1596 -- original_node pointers, given that the operands themselves may
1597 -- have been rewritten. If the call was itself a rewriting of an
1598 -- operator node, nothing to do.
1600 if ASIS_Mode
1603 then
1604 declare
1612 begin
1617 -- If the original call has named associations, replace the
1618 -- explicit actual parameter in the association with the proper
1619 -- resolved operand.
1624 then
1627 else
1632 else
1639 then
1642 else
1647 else
1651 else
1655 else
1665 -------------------
1666 -- Operator_Kind --
1667 -------------------
1669 function Operator_Kind
1672 is
1675 begin
1676 -- Use CASE statement or array???
1713 else
1717 -- Unary operators
1719 else
1728 else
1736 ----------------------------
1737 -- Preanalyze_And_Resolve --
1738 ----------------------------
1743 begin
1747 -- Normally, we suppress all checks for this preanalysis. There is no
1748 -- point in processing them now, since they will be applied properly
1749 -- and in the proper location when the default expressions reanalyzed
1750 -- and reexpanded later on. We will also have more information at that
1751 -- point for possible suppression of individual checks.
1753 -- However, in SPARK mode, most expansion is suppressed, and this
1754 -- later reanalysis and reexpansion may not occur. SPARK mode does
1755 -- require the setting of checking flags for proof purposes, so we
1756 -- do the SPARK preanalysis without suppressing checks.
1758 -- This special handling for SPARK mode is required for example in the
1759 -- case of Ada 2012 constructs such as quantified expressions, which are
1760 -- expanded in two separate steps.
1764 else
1768 Expander_Mode_Restore;
1772 -- Version without context type
1777 begin
1784 Expander_Mode_Restore;
1788 ----------------------------------
1789 -- Replace_Actual_Discriminants --
1790 ----------------------------------
1797 -- Comment needed???
1799 -------------------
1800 -- Process_Discr --
1801 -------------------
1806 begin
1812 then
1828 -- Start of processing for Replace_Actual_Discriminants
1830 begin
1844 else
1849 -------------
1850 -- Resolve --
1851 -------------
1867 -- Determine whether a node comes from a predefined library unit or
1868 -- Standard.
1871 -- Try and fix up a literal so that it matches its expected type. New
1872 -- literals are manufactured if necessary to avoid cascaded errors.
1875 -- Additional diagnostics when an ambiguous call has an ambiguous
1876 -- argument (typically a controlling actual).
1879 -- Called when attempt at resolving current expression fails
1881 ------------------------------------
1882 -- Comes_From_Predefined_Lib_Unit --
1883 -------------------------------------
1886 begin
1887 return
1889 or else Is_Predefined_File_Name
1893 --------------------
1894 -- Patch_Up_Value --
1895 --------------------
1898 begin
1915 then
1920 Char_Literal_Value =>
1936 -------------------------------
1937 -- Report_Ambiguous_Argument --
1938 -------------------------------
1945 begin
1949 then
1952 -- Could use comments on what is going on here???
1960 else
1969 -----------------------
1970 -- Resolution_Failed --
1971 -----------------------
1974 begin
1980 -- The caller will return without calling the expander, so we need
1981 -- to set the analyzed flag. Note that it is fine to set Analyzed
1982 -- to True even if we are in the middle of a shallow analysis,
1983 -- (see the spec of sem for more details) since this is an error
1984 -- situation anyway, and there is no point in repeating the
1985 -- analysis later (indeed it won't work to repeat it later, since
1986 -- we haven't got a clear resolution of which entity is being
1987 -- referenced.)
1993 -- Start of processing for Resolve
1995 begin
2000 -- Access attribute on remote subprogram cannot be used for a non-remote
2001 -- access-to-subprogram type.
2005 Name_Unrestricted_Access,
2006 Name_Unchecked_Access)
2012 then
2013 Error_Msg_N
2019 -- If the context is a Remote_Access_To_Subprogram, access attributes
2020 -- must be resolved with the corresponding fat pointer. There is no need
2021 -- to check for the attribute name since the return type of an
2022 -- attribute is never a remote type.
2027 then
2028 declare
2036 begin
2037 -- Check that Typ is a remote access-to-subprogram type
2041 -- Prefix (N) must statically denote a remote subprogram
2042 -- declared in a package specification.
2046 Attr = Attribute_Unrestricted_Access
2047 then
2062 or else
2064 then
2066 Error_Msg_N
2068 N);
2071 -- If we are generating code in distributed mode, perform
2072 -- semantic checks against corresponding remote entities.
2074 if Expander_Active
2076 then
2077 Check_Subtype_Conformant
2079 Old_Id => Designated_Type
2105 then
2110 -- Return if already analyzed
2117 -- Any case of Any_Type as the Etype value means that we had a
2118 -- previous error.
2127 -- The resolution of an Expression_With_Actions is determined by
2128 -- its Expression.
2136 -- If not overloaded, then we know the type, and all that needs doing
2137 -- is to check that this type is compatible with the context.
2143 -- In the overloaded case, we must select the interpretation that
2144 -- is compatible with the context (i.e. the type passed to Resolve)
2146 else
2147 -- Loop through possible interpretations
2156 -- We are only interested in interpretations that are compatible
2157 -- with the expected type, any other interpretations are ignored.
2162 Write_Eol;
2165 else
2166 -- Skip the current interpretation if it is disabled by an
2167 -- abstract operator. This action is performed only when the
2168 -- type against which we are resolving is the same as the
2169 -- type of the interpretation.
2176 then
2184 -- First matching interpretation
2192 -- Matching interpretation that is not the first, maybe an
2193 -- error, but there are some cases where preference rules are
2194 -- used to choose between the two possibilities. These and
2195 -- some more obscure cases are handled in Disambiguate.
2197 else
2198 -- If the current statement is part of a predefined library
2199 -- unit, then all interpretations which come from user level
2200 -- packages should not be considered. Check previous and
2201 -- current one.
2209 -- Previous interpretation must be discarded
2219 -- Otherwise apply further disambiguation steps
2224 -- Disambiguation has succeeded. Skip the remaining
2225 -- interpretations.
2235 else
2236 -- Before we issue an ambiguity complaint, check for
2237 -- the case of a subprogram call where at least one
2238 -- of the arguments is Any_Type, and if so, suppress
2239 -- the message, since it is a cascaded error.
2242 declare
2246 begin
2258 Write_Eol;
2271 then
2276 then
2280 -- Not that special case, so issue message using the
2281 -- flag Ambiguous to control printing of the header
2282 -- message only at the start of an ambiguous set.
2287 then
2288 Error_Msg_N
2291 else
2292 Error_Msg_NE -- CODEFIX
2300 Error_Msg_N
2302 else
2303 Error_Msg_N -- CODEFIX
2309 then
2310 Report_Ambiguous_Argument;
2316 -- By default, the error message refers to the candidate
2317 -- interpretation. But if it is a predefined operator, it
2318 -- is implicitly declared at the declaration of the type
2319 -- of the operand. Recover the sloc of that declaration
2320 -- for the error message.
2326 Standard_Standard
2327 then
2332 then
2340 Standard_Standard
2341 then
2346 then
2350 -- If this is an indirect call, use the subprogram_type
2351 -- in the message, to have a meaningful location. Also
2352 -- indicate if this is an inherited operation, created
2353 -- by a type declaration.
2358 then
2360 Error_Msg_Sloc :=
2362 else
2369 then
2370 -- Special-case the message for universal_fixed
2371 -- operators, which are not declared with the type
2372 -- of the operand, but appear forever in Standard.
2376 then
2377 Error_Msg_N
2380 else
2381 Error_Msg_N
2385 elsif
2387 then
2388 Error_Msg_N
2390 else
2391 Error_Msg_N -- CODEFIX
2398 -- We have a matching interpretation, Expr_Type is the type
2399 -- from this interpretation, and Seen is the entity.
2401 -- For an operator, just set the entity name. The type will be
2402 -- set by the specific operator resolution routine.
2417 -- AI05-0139-2: Expression is overloaded because type has
2418 -- implicit dereference. If type matches context, no implicit
2419 -- dereference is involved.
2430 then
2431 -- If the node is a general indexing, the dereference is
2432 -- is inserted when resolving the rewritten form, else
2433 -- insert it now.
2437 then
2441 -- For an explicit dereference, attribute reference, range,
2442 -- short-circuit form (which is not an operator node), or call
2443 -- with a name that is an explicit dereference, there is
2444 -- nothing to be done at this point.
2447 N_Attribute_Reference,
2448 N_And_Then,
2449 N_Indexed_Component,
2450 N_Or_Else,
2451 N_Range,
2452 N_Selected_Component,
2453 N_Slice)
2455 then
2458 -- For procedure or function calls, set the type of the name,
2459 -- and also the entity pointer for the prefix.
2463 then
2470 then
2475 -- For all other cases, just set the type of the Name
2477 else
2485 -- Move to next interpretation
2493 -- At this stage Found indicates whether or not an acceptable
2494 -- interpretation exists. If not, then we have an error, except that if
2495 -- the context is Any_Type as a result of some other error, then we
2496 -- suppress the error report.
2501 -- If type we are looking for is Void, then this is the procedure
2502 -- call case, and the error is simply that what we gave is not a
2503 -- procedure name (we think of procedure calls as expressions with
2504 -- types internally, but the user doesn't think of them this way).
2508 -- Special case message if function used as a procedure
2513 then
2514 Error_Msg_NE
2518 -- Otherwise give general message (not clear what cases this
2519 -- covers, but no harm in providing for them).
2521 else
2527 -- Otherwise we do have a subexpression with the wrong type
2529 -- Check for the case of an allocator which uses an access type
2530 -- instead of the designated type. This is a common error and we
2531 -- specialize the message, posting an error on the operand of the
2532 -- allocator, complaining that we expected the designated type of
2533 -- the allocator.
2539 then
2543 -- Check for view mismatch on Null in instances, for which the
2544 -- view-swapping mechanism has no identifier.
2550 then
2555 -- Check for an aggregate. Sometimes we can get bogus aggregates
2556 -- from misuse of parentheses, and we are about to complain about
2557 -- the aggregate without even looking inside it.
2559 -- Instead, if we have an aggregate of type Any_Composite, then
2560 -- analyze and resolve the component fields, and then only issue
2561 -- another message if we get no errors doing this (otherwise
2562 -- assume that the errors in the aggregate caused the problem).
2566 then
2567 -- Disable expansion in any case. If there is a type mismatch
2568 -- it may be fatal to try to expand the aggregate. The flag
2569 -- would otherwise be set to false when the error is posted.
2573 declare
2575 -- Check one aggregate, and set Found to True if we have a
2576 -- definite error in any of its elements
2579 -- Check one element of aggregate and set Found to True if
2580 -- we definitely have an error in the element.
2582 ----------------
2583 -- Check_Aggr --
2584 ----------------
2589 begin
2602 -- If this is a default-initialized component, then
2603 -- there is nothing to check. The box will be
2604 -- replaced by the appropriate call during late
2605 -- expansion.
2616 ----------------
2617 -- Check_Elmt --
2618 ----------------
2621 begin
2622 -- If we have a nested aggregate, go inside it (to
2623 -- attempt a naked analyze-resolve of the aggregate can
2624 -- cause undesirable cascaded errors). Do not resolve
2625 -- expression if it needs a type from context, as for
2626 -- integer * fixed expression.
2631 else
2636 then
2646 begin
2651 -- Looks like we have a type error, but check for special case
2652 -- of Address wanted, integer found, with the configuration pragma
2653 -- Allow_Integer_Address active. If we have this case, introduce
2654 -- an unchecked conversion to allow the integer expression to be
2655 -- treated as an Address. The reverse case of integer wanted,
2656 -- Address found, is treated in an analogous manner.
2664 -- That special Allow_Integer_Address check did not appply, so we
2665 -- have a real type error. If an error message was issued already,
2666 -- Found got reset to True, so if it's still False, issue standard
2667 -- Wrong_Type message.
2671 declare
2674 begin
2680 -- Protected operation: retrieve operation name
2684 else
2689 Error_Msg_NE
2695 declare
2699 begin
2706 Error_Msg_NE
2712 else
2716 else
2722 Resolution_Failed;
2725 -- Test if we have more than one interpretation for the context
2728 Resolution_Failed;
2731 -- Only one intepretation
2733 else
2734 -- In Ada 2005, if we have something like "X : T := 2 + 2;", where
2735 -- the "+" on T is abstract, and the operands are of universal type,
2736 -- the above code will have (incorrectly) resolved the "+" to the
2737 -- universal one in Standard. Therefore check for this case and give
2738 -- an error. We can't do this earlier, because it would cause legal
2739 -- cases to get errors (when some other type has an abstract "+").
2745 then
2750 then
2751 Error_Msg_NE
2760 -- Here we have an acceptable interpretation for the context
2762 -- Propagate type information and normalize tree for various
2763 -- predefined operations. If the context only imposes a class of
2764 -- types, rather than a specific type, propagate the actual type
2765 -- downward.
2771 Typ = Any_Discrete
2772 then
2775 -- Any_Fixed is legal in a real context only if a specific fixed-
2776 -- point type is imposed. If Norman Cohen can be confused by this,
2777 -- it deserves a separate message.
2781 then
2788 -- A user-defined operator is transformed into a function call at
2789 -- this point, so that further processing knows that operators are
2790 -- really operators (i.e. are predefined operators). User-defined
2791 -- operators that are intrinsic are just renamings of the predefined
2792 -- ones, and need not be turned into calls either, but if they rename
2793 -- a different operator, we must transform the node accordingly.
2794 -- Instantiations of Unchecked_Conversion are intrinsic but are
2795 -- treated as functions, even if given an operator designator.
2800 then
2806 and then
2808 N_Subprogram_Renaming_Declaration
2809 then
2812 -- If the node is rewritten, it will be fully resolved in
2813 -- Rewrite_Renamed_Operator.
2823 when N_Aggregate => Resolve_Aggregate (N, Ctx_Type);
2825 when N_Allocator => Resolve_Allocator (N, Ctx_Type);
2827 when N_Short_Circuit
2828 => Resolve_Short_Circuit (N, Ctx_Type);
2830 when N_Attribute_Reference
2831 => Resolve_Attribute (N, Ctx_Type);
2833 when N_Case_Expression
2834 => Resolve_Case_Expression (N, Ctx_Type);
2836 when N_Character_Literal
2837 => Resolve_Character_Literal (N, Ctx_Type);
2839 when N_Expanded_Name
2840 => Resolve_Entity_Name (N, Ctx_Type);
2842 when N_Explicit_Dereference
2843 => Resolve_Explicit_Dereference (N, Ctx_Type);
2845 when N_Expression_With_Actions
2846 => Resolve_Expression_With_Actions (N, Ctx_Type);
2848 when N_Extension_Aggregate
2849 => Resolve_Extension_Aggregate (N, Ctx_Type);
2851 when N_Function_Call
2852 => Resolve_Call (N, Ctx_Type);
2854 when N_Identifier
2855 => Resolve_Entity_Name (N, Ctx_Type);
2857 when N_If_Expression
2858 => Resolve_If_Expression (N, Ctx_Type);
2860 when N_Indexed_Component
2861 => Resolve_Indexed_Component (N, Ctx_Type);
2863 when N_Integer_Literal
2864 => Resolve_Integer_Literal (N, Ctx_Type);
2866 when N_Membership_Test
2867 => Resolve_Membership_Op (N, Ctx_Type);
2869 when N_Null => Resolve_Null (N, Ctx_Type);
2871 when N_Op_And | N_Op_Or | N_Op_Xor
2872 => Resolve_Logical_Op (N, Ctx_Type);
2874 when N_Op_Eq | N_Op_Ne
2875 => Resolve_Equality_Op (N, Ctx_Type);
2877 when N_Op_Lt | N_Op_Le | N_Op_Gt | N_Op_Ge
2878 => Resolve_Comparison_Op (N, Ctx_Type);
2880 when N_Op_Not => Resolve_Op_Not (N, Ctx_Type);
2882 when N_Op_Add | N_Op_Subtract | N_Op_Multiply |
2883 N_Op_Divide | N_Op_Mod | N_Op_Rem
2885 => Resolve_Arithmetic_Op (N, Ctx_Type);
2887 when N_Op_Concat => Resolve_Op_Concat (N, Ctx_Type);
2889 when N_Op_Expon => Resolve_Op_Expon (N, Ctx_Type);
2891 when N_Op_Plus | N_Op_Minus | N_Op_Abs
2892 => Resolve_Unary_Op (N, Ctx_Type);
2894 when N_Op_Shift => Resolve_Shift (N, Ctx_Type);
2896 when N_Procedure_Call_Statement
2897 => Resolve_Call (N, Ctx_Type);
2899 when N_Operator_Symbol
2900 => Resolve_Operator_Symbol (N, Ctx_Type);
2902 when N_Qualified_Expression
2903 => Resolve_Qualified_Expression (N, Ctx_Type);
2905 -- Why is the following null, needs a comment ???
2907 when N_Quantified_Expression
2908 => null;
2910 when N_Raise_Expression
2911 => Resolve_Raise_Expression (N, Ctx_Type);
2913 when N_Raise_xxx_Error
2914 => Set_Etype (N, Ctx_Type);
2916 when N_Range => Resolve_Range (N, Ctx_Type);
2918 when N_Real_Literal
2919 => Resolve_Real_Literal (N, Ctx_Type);
2921 when N_Reference => Resolve_Reference (N, Ctx_Type);
2923 when N_Selected_Component
2924 => Resolve_Selected_Component (N, Ctx_Type);
2926 when N_Slice => Resolve_Slice (N, Ctx_Type);
2928 when N_String_Literal
2929 => Resolve_String_Literal (N, Ctx_Type);
2931 when N_Type_Conversion
2932 => Resolve_Type_Conversion (N, Ctx_Type);
2934 when N_Unchecked_Expression =>
2935 Resolve_Unchecked_Expression (N, Ctx_Type);
2937 when N_Unchecked_Type_Conversion =>
2938 Resolve_Unchecked_Type_Conversion (N, Ctx_Type);
2939 end case;
2941 -- Ada 2012 (AI05-0149): Apply an (implicit) conversion to an
2942 -- expression of an anonymous access type that occurs in the context
2943 -- of a named general access type, except when the expression is that
2944 -- of a membership test. This ensures proper legality checking in
2945 -- terms of allowed conversions (expressions that would be illegal to
2946 -- convert implicitly are allowed in membership tests).
2948 if Ada_Version >= Ada_2012
2949 and then Ekind (Ctx_Type) = E_General_Access_Type
2950 and then Ekind (Etype (N)) = E_Anonymous_Access_Type
2951 and then Nkind (Parent (N)) not in N_Membership_Test
2952 then
2953 Rewrite (N, Convert_To (Ctx_Type, Relocate_Node (N)));
2954 Analyze_And_Resolve (N, Ctx_Type);
2955 end if;
2957 -- If the subexpression was replaced by a non-subexpression, then
2958 -- all we do is to expand it. The only legitimate case we know of
2959 -- is converting procedure call statement to entry call statements,
2960 -- but there may be others, so we are making this test general.
2962 if Nkind (N) not in N_Subexpr then
2963 Debug_A_Exit ("resolving ", N, " (done)");
2964 Expand (N);
2965 return;
2966 end if;
2968 -- The expression is definitely NOT overloaded at this point, so
2969 -- we reset the Is_Overloaded flag to avoid any confusion when
2970 -- reanalyzing the node.
2972 Set_Is_Overloaded (N, False);
2974 -- Freeze expression type, entity if it is a name, and designated
2975 -- type if it is an allocator (RM 13.14(10,11,13)).
2977 -- Now that the resolution of the type of the node is complete, and
2978 -- we did not detect an error, we can expand this node. We skip the
2979 -- expand call if we are in a default expression, see section
2980 -- "Handling of Default Expressions" in Sem spec.
2982 Debug_A_Exit ("resolving ", N, " (done)");
2984 -- We unconditionally freeze the expression, even if we are in
2985 -- default expression mode (the Freeze_Expression routine tests this
2986 -- flag and only freezes static types if it is set).
2988 -- Ada 2012 (AI05-177): The declaration of an expression function
2989 -- does not cause freezing, but we never reach here in that case.
2990 -- Here we are resolving the corresponding expanded body, so we do
2991 -- need to perform normal freezing.
2993 Freeze_Expression (N);
2995 -- Now we can do the expansion
2997 Expand (N);
2998 end if;
2999 end Resolve;
3001 -------------
3002 -- Resolve --
3003 -------------
3005 -- Version with check(s) suppressed
3007 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id) is
3008 begin
3009 if Suppress = All_Checks then
3010 declare
3011 Sva : constant Suppress_Array := Scope_Suppress.Suppress;
3012 begin
3013 Scope_Suppress.Suppress := (others => True);
3014 Resolve (N, Typ);
3015 Scope_Suppress.Suppress := Sva;
3016 end;
3018 else
3019 declare
3020 Svg : constant Boolean := Scope_Suppress.Suppress (Suppress);
3021 begin
3022 Scope_Suppress.Suppress (Suppress) := True;
3023 Resolve (N, Typ);
3024 Scope_Suppress.Suppress (Suppress) := Svg;
3025 end;
3026 end if;
3027 end Resolve;
3029 -------------
3030 -- Resolve --
3031 -------------
3033 -- Version with implicit type
3035 procedure Resolve (N : Node_Id) is
3036 begin
3037 Resolve (N, Etype (N));
3038 end Resolve;
3040 ---------------------
3041 -- Resolve_Actuals --
3042 ---------------------
3044 procedure Resolve_Actuals (N : Node_Id; Nam : Entity_Id) is
3045 Loc : constant Source_Ptr := Sloc (N);
3046 A : Node_Id;
3047 A_Id : Entity_Id;
3048 A_Typ : Entity_Id;
3049 F : Entity_Id;
3050 F_Typ : Entity_Id;
3051 Prev : Node_Id := Empty;
3052 Orig_A : Node_Id;
3054 procedure Check_Aliased_Parameter;
3055 -- Check rules on aliased parameters and related accessibility rules
3056 -- in (RM 3.10.2 (10.2-10.4)).
3058 procedure Check_Argument_Order;
3059 -- Performs a check for the case where the actuals are all simple
3060 -- identifiers that correspond to the formal names, but in the wrong
3061 -- order, which is considered suspicious and cause for a warning.
3063 procedure Check_Prefixed_Call;
3064 -- If the original node is an overloaded call in prefix notation,
3066 -- Try_Object_Operation has already verified that there is a valid
3067 -- interpretation, but the form of the actual can only be determined
3068 -- once the primitive operation is identified.
3071 -- If the actual is missing in a call, insert in the actuals list
3072 -- an instance of the default expression. The insertion is always
3073 -- a named association.
3075 procedure Property_Error
3079 -- Emit an error concerning variable Var with entity Var_Id that has
3080 -- enabled property Prop_Nam when it acts as an actual parameter in a
3081 -- call and the corresponding formal parameter is of mode IN.
3084 -- Check whether T1 and T2, or their full views, are derived from a
3085 -- common type. Used to enforce the restrictions on array conversions
3086 -- of AI95-00246.
3089 -- Predicate to determine whether an actual that is a concatenation
3090 -- will be evaluated statically and does not need a transient scope.
3091 -- This must be determined before the actual is resolved and expanded
3092 -- because if needed the transient scope must be introduced earlier.
3094 -----------------------------
3095 -- Check_Aliased_Parameter --
3096 -----------------------------
3101 begin
3109 else
3116 -- In a generic body assume the worst for generic formals:
3117 -- they can have a constrained partial view (AI05-041).
3123 then
3126 else
3131 else
3143 then
3151 then
3152 Error_Msg_N
3158 --------------------------
3159 -- Check_Argument_Order --
3160 --------------------------
3163 begin
3164 -- Nothing to do if no parameters, or original node is neither a
3165 -- function call nor a procedure call statement (happens in the
3166 -- operator-transformed-to-function call case), or the call does
3167 -- not come from source, or this warning is off.
3169 if not Warn_On_Parameter_Order
3173 then
3177 declare
3180 begin
3181 -- Nothing to do if only one parameter
3187 -- Here if at least two arguments
3189 declare
3195 -- Set True if an out of order case is found
3197 begin
3198 -- Collect identifier names of actuals, fail if any actual is
3199 -- not a simple identifier, and record max length of name.
3205 else
3211 -- If we got this far, all actuals are identifiers and the list
3212 -- of their names is stored in the Actuals array.
3217 -- If we ran out of formals, that's odd, probably an error
3218 -- which will be detected elsewhere, but abandon the search.
3224 -- If name matches and is in order OK
3229 else
3230 -- If no match, see if it is elsewhere in list and if so
3231 -- flag potential wrong order if type is compatible.
3235 and then
3237 then
3243 -- No match
3251 -- If Formals left over, also probably an error, skip warning
3257 -- Here we give the warning if something was out of order
3260 Error_Msg_N
3267 -------------------------
3268 -- Check_Prefixed_Call --
3269 -------------------------
3278 begin
3279 -- Check whether the call is a prefixed call, with or without
3280 -- additional actuals.
3283 or else
3289 then
3292 then
3293 -- Introduce dereference on object in prefix
3295 New_A :=
3303 then
3304 -- Introduce an implicit 'Access in prefix
3307 Error_Msg_NE
3323 --------------------
3324 -- Insert_Default --
3325 --------------------
3331 begin
3332 -- Missing argument in call, nothing to insert
3337 else
3338 -- Note that we do a full New_Copy_Tree, so that any associated
3339 -- Itypes are properly copied. This may not be needed any more,
3340 -- but it does no harm as a safety measure. Defaults of a generic
3341 -- formal may be out of bounds of the corresponding actual (see
3342 -- cc1311b) and an additional check may be required.
3344 Actval :=
3345 New_Copy_Tree
3352 then
3358 then
3361 then
3362 -- If default is a real literal, do not introduce a
3363 -- conversion whose effect may depend on the run-time
3364 -- size of universal real.
3368 else
3379 -- Resolve aggregates with their base type, to avoid scope
3380 -- anomalies: the subtype was first built in the subprogram
3381 -- declaration, and the current call may be nested.
3385 else
3389 else
3392 -- See note above concerning aggregates
3396 then
3399 -- Resolve entities with their own type, which may differ from
3400 -- the type of a reference in a generic context (the view
3401 -- swapping mechanism did not anticipate the re-analysis of
3402 -- default values in calls).
3407 else
3412 -- If default is a tag indeterminate function call, propagate tag
3413 -- to obtain proper dispatching.
3417 then
3423 -- If the default expression raises constraint error, then just
3424 -- silently replace it with an N_Raise_Constraint_Error node, since
3425 -- we already gave the warning on the subprogram spec. If node is
3426 -- already a Raise_Constraint_Error leave as is, to prevent loops in
3427 -- the warnings removal machinery.
3431 then
3439 Assoc :=
3444 -- Case of insertion is first named actual
3448 then
3455 else
3459 else
3463 -- Case of insertion is not first named actual
3465 else
3466 Set_Next_Named_Actual
3478 --------------------
3479 -- Property_Error --
3480 --------------------
3482 procedure Property_Error
3486 is
3487 begin
3489 Error_Msg_NE
3495 -------------------
3496 -- Same_Ancestor --
3497 -------------------
3503 begin
3506 then
3512 then
3519 --------------------------
3520 -- Static_Concatenation --
3521 --------------------------
3524 begin
3531 -- Concatenation is static when both operands are static and
3532 -- the concatenation operator is a predefined one.
3535 and then
3537 and then
3542 declare
3544 begin
3547 and then
3551 else
3557 -- Start of processing for Resolve_Actuals
3559 begin
3560 Check_Argument_Order;
3564 Check_Prefixed_Call;
3573 -- If we have an error in any actual or formal, indicated by a type
3574 -- of Any_Type, then abandon resolution attempt, and set result type
3575 -- to Any_Type. Skip this if the actual is a Raise_Expression, whose
3576 -- type is imposed from context.
3580 then
3587 -- Case where actual is present
3589 -- If the actual is an entity, generate a reference to it now. We
3590 -- do this before the actual is resolved, because a formal of some
3591 -- protected subprogram, or a task discriminant, will be rewritten
3592 -- during expansion, and the source entity reference may be lost.
3597 then
3603 then
3610 -- RM 6.4.1(12): For an out parameter that is passed by
3611 -- copy, the formal parameter object is created, and:
3613 -- * For an access type, the formal parameter is initialized
3614 -- from the value of the actual, without checking that the
3615 -- value satisfies any constraint, any predicate, or any
3616 -- exclusion of the null value.
3618 -- * For a scalar type that has the Default_Value aspect
3619 -- specified, the formal parameter is initialized from the
3620 -- value of the actual, without checking that the value
3621 -- satisfies any constraint or any predicate.
3622 -- I do not understand why this case is included??? this is
3623 -- not a case where an OUT parameter is treated as IN OUT.
3625 -- * For a composite type with discriminants or that has
3626 -- implicit initial values for any subcomponents, the
3627 -- behavior is as for an in out parameter passed by copy.
3629 -- Hence for these cases we generate the read reference now
3630 -- (the write reference will be generated later by
3631 -- Note_Possible_Modification).
3634 and then
3636 or else
3638 and then
3640 or else
3643 or else Is_Partially_Initialized_Type
3645 then
3655 then
3656 -- If style checking mode on, check match of formal name
3664 -- If the formal is Out or In_Out, do not resolve and expand the
3665 -- conversion, because it is subsequently expanded into explicit
3666 -- temporaries and assignments. However, the object of the
3667 -- conversion can be resolved. An exception is the case of tagged
3668 -- type conversion with a class-wide actual. In that case we want
3669 -- the tag check to occur and no temporary will be needed (no
3670 -- representation change can occur) and the parameter is passed by
3671 -- reference, so we go ahead and resolve the type conversion.
3672 -- Another exception is the case of reference to component or
3673 -- subcomponent of a bit-packed array, in which case we want to
3674 -- defer expansion to the point the in and out assignments are
3675 -- performed.
3680 then
3683 then
3684 -- In a view conversion, the conversion must be legal in
3685 -- both directions, and thus both component types must be
3686 -- aliased, or neither (4.6 (8)).
3688 -- The extra rule in 4.6 (24.9.2) seems unduly restrictive:
3689 -- the privacy requirement should not apply to generic
3690 -- types, and should be checked in an instance. ARG query
3691 -- is in order ???
3695 then
3696 Error_Msg_N
3700 -- Comment here??? what set of cases???
3702 elsif
3704 then
3705 -- Check view conv between unrelated by ref array types
3709 then
3710 Error_Msg_N
3714 -- In Ada 2005 mode, check view conversion component
3715 -- type cannot be private, tagged, or volatile. Note
3716 -- that we only apply this to source conversions. The
3717 -- generated code can contain conversions which are
3718 -- not subject to this test, and we cannot extract the
3719 -- component type in such cases since it is not present.
3723 then
3724 declare
3726 Component_Type
3728 begin
3733 then
3734 Error_Msg_N
3745 -- Resolve expression if conversion is all OK
3750 then
3754 -- If the actual is a function call that returns a limited
3755 -- unconstrained object that needs finalization, create a
3756 -- transient scope for it, so that it can receive the proper
3757 -- finalization list.
3762 and then Expander_Active
3764 then
3768 -- A small optimization: if one of the actuals is a concatenation
3769 -- create a block around a procedure call to recover stack space.
3770 -- This alleviates stack usage when several procedure calls in
3771 -- the same statement list use concatenation. We do not perform
3772 -- this wrapping for code statements, where the argument is a
3773 -- static string, and we want to preserve warnings involving
3774 -- sequences of such statements.
3778 and then Expander_Active
3779 and then
3783 then
3787 else
3791 and then
3794 then
3795 Error_Msg_N
3808 -- (Ada 2005: AI-251): If the actual is an allocator whose
3809 -- directly designated type is a class-wide interface, we build
3810 -- an anonymous access type to use it as the type of the
3811 -- allocator. Later, when the subprogram call is expanded, if
3812 -- the interface has a secondary dispatch table the expander
3813 -- will add a type conversion to force the correct displacement
3814 -- of the pointer.
3817 declare
3823 begin
3826 then
3829 Set_Directly_Designated_Type
3834 -- Ada 2005, AI-162:If the actual is an allocator, the
3835 -- innermost enclosing statement is the master of the
3836 -- created object. This needs to be done with expansion
3837 -- enabled only, otherwise the transient scope will not
3838 -- be removed in the expansion of the wrapped construct.
3841 and then Expander_Active
3842 then
3852 -- (Ada 2005): The call may be to a primitive operation of a
3853 -- tagged synchronized type, declared outside of the type. In
3854 -- this case the controlling actual must be converted to its
3855 -- corresponding record type, which is the formal type. The
3856 -- actual may be a subtype, either because of a constraint or
3857 -- because it is a generic actual, so use base type to locate
3858 -- concurrent type.
3865 then
3866 -- If the actual is overloaded, look for an interpretation
3867 -- that has a synchronized type.
3872 else
3873 declare
3877 begin
3882 then
3892 declare
3895 begin
3898 else
3902 -- Tagged synchronized type (case 1): the actual is a
3903 -- concurrent type.
3907 then
3909 Unchecked_Convert_To
3913 -- Tagged synchronized type (case 2): the formal is a
3914 -- concurrent type.
3917 and then Present
3922 then
3925 -- Common case
3927 else
3932 -- Not a synchronized operation
3934 else
3942 -- An actual cannot be an untagged formal incomplete type
3947 then
3948 Error_Msg_N
3954 N_Procedure_Call_Statement)
3955 then
3956 -- In formal mode, check that actual parameters matching
3957 -- formals of tagged types are objects (or ancestor type
3958 -- conversions of objects), not general expressions.
3965 declare
3970 begin
3972 Check_SPARK_05_Restriction
3975 -- In formal mode, the only view conversions are those
3976 -- involving ancestor conversion of an extended type.
3978 elsif not
3984 then
3985 if Ekind_In
3987 then
3988 Check_SPARK_05_Restriction
3991 else
3992 Check_SPARK_05_Restriction
3996 else
4001 else
4005 -- In formal mode, the only view conversions are those
4006 -- involving ancestor conversion of an extended type.
4010 then
4011 Check_SPARK_05_Restriction
4017 -- has warnings suppressed, then we reset Never_Set_In_Source for
4018 -- the calling entity. The reason for this is to catch cases like
4019 -- GNAT.Spitbol.Patterns.Vstring_Var where the called subprogram
4020 -- uses trickery to modify an IN parameter.
4027 then
4031 -- Perform error checks for IN and IN OUT parameters
4035 -- Check unset reference. For scalar parameters, it is clearly
4036 -- wrong to pass an uninitialized value as either an IN or
4037 -- IN-OUT parameter. For composites, it is also clearly an
4038 -- error to pass a completely uninitialized value as an IN
4039 -- parameter, but the case of IN OUT is trickier. We prefer
4040 -- not to give a warning here. For example, suppose there is
4041 -- a routine that sets some component of a record to False.
4042 -- It is perfectly reasonable to make this IN-OUT and allow
4043 -- either initialized or uninitialized records to be passed
4044 -- in this case.
4046 -- For partially initialized composite values, we also avoid
4047 -- warnings, since it is quite likely that we are passing a
4048 -- partially initialized value and only the initialized fields
4049 -- will in fact be read in the subprogram.
4054 then
4058 -- In Ada 83 we cannot pass an OUT parameter as an IN or IN OUT
4059 -- actual to a nested call, since this constitutes a reading of
4060 -- the parameter, which is not allowed.
4064 then
4066 Error_Msg_N
4069 -- An effectively volatile OUT parameter cannot act as IN or
4070 -- IN OUT actual in a call (SPARK RM 7.1.3(11)).
4074 then
4075 Error_Msg_N
4081 -- Case of OUT or IN OUT parameter
4085 -- For an Out parameter, check for useless assignment. Note
4086 -- that we can't set Last_Assignment this early, because we may
4087 -- kill current values in Resolve_Call, and that call would
4088 -- clobber the Last_Assignment field.
4090 -- Note: call Warn_On_Useless_Assignment before doing the check
4091 -- below for Is_OK_Variable_For_Out_Formal so that the setting
4092 -- of Referenced_As_LHS/Referenced_As_Out_Formal properly
4093 -- reflects the last assignment, not this one.
4100 then
4105 -- Validate the form of the actual. Note that the call to
4106 -- Is_OK_Variable_For_Out_Formal generates the required
4107 -- reference in this case.
4109 -- A call to an initialization procedure for an aggregate
4110 -- component may initialize a nested component of a constant
4111 -- designated object. In this context the object is variable.
4115 then
4119 and then
4122 then
4123 Error_Msg_N
4129 -- What's the following about???
4133 else
4134 Kill_All_Checks;
4143 -- Apply appropriate constraint/predicate checks for IN [OUT] case
4147 -- Apply predicate tests except in certain special cases. Note
4148 -- that it might be more consistent to apply these only when
4149 -- expansion is active (in Exp_Ch6.Expand_Actuals), as we do
4150 -- for the outbound predicate tests ???
4156 -- Apply required constraint checks
4158 -- Gigi looks at the check flag and uses the appropriate types.
4159 -- For now since one flag is used there is an optimization
4160 -- which might not be done in the IN OUT case since Gigi does
4161 -- not do any analysis. More thought required about this ???
4163 -- In fact is this comment obsolete??? doesn't the expander now
4164 -- generate all these tests anyway???
4177 then
4180 -- For view conversions of a discriminated object, apply
4181 -- check to object itself, the conversion alreay has the
4182 -- proper type.
4186 then
4193 then
4199 then
4202 else
4206 -- Ada 2005 (AI-231): Note that the controlling parameter case
4207 -- already existed in Ada 95, which is partially checked
4208 -- elsewhere (see Checks), and we don't want the warning
4209 -- message to differ.
4214 then
4216 Apply_Compile_Time_Constraint_Error
4222 Apply_Compile_Time_Constraint_Error
4231 -- Checks for OUT parameters and IN OUT parameters
4235 -- If there is a type conversion, to make sure the return value
4236 -- meets the constraints of the variable before the conversion.
4240 Apply_Scalar_Range_Check
4242 else
4243 Apply_Range_Check
4247 -- If no conversion apply scalar range checks and length checks
4248 -- base on the subtype of the actual (NOT that of the formal).
4250 else
4255 then
4257 else
4262 -- Note: we do not apply the predicate checks for the case of
4263 -- OUT and IN OUT parameters. They are instead applied in the
4264 -- Expand_Actuals routine in Exp_Ch6.
4267 -- An actual associated with an access parameter is implicitly
4268 -- converted to the anonymous access type of the formal and must
4269 -- satisfy the legality checks for access conversions.
4273 Error_Msg_N
4277 -- If the actual is an access selected component of a variable,
4278 -- the call may modify its designated object. It is reasonable
4279 -- to treat this as a potential modification of the enclosing
4280 -- record, to prevent spurious warnings that it should be
4281 -- declared as a constant, because intuitively programmers
4282 -- regard the designated subcomponent as part of the record.
4287 then
4292 -- Check bad case of atomic/volatile argument (RM C.6(12))
4296 then
4299 then
4300 Error_Msg_NE
4306 then
4307 Error_Msg_NE
4313 -- Check that subprograms don't have improper controlling
4314 -- arguments (RM 3.9.2 (9)).
4316 -- A primitive operation may have an access parameter of an
4317 -- incomplete tagged type, but a dispatching call is illegal
4318 -- if the type is still incomplete.
4324 declare
4326 begin
4330 then
4331 Error_Msg_NE
4342 -- Apply legality rule 3.9.2 (9/1)
4347 and then not In_Instance
4348 then
4353 Error_Msg_NE
4357 -- Apply the checks described in 3.10.2(27): if the context is a
4358 -- specific access-to-object, the actual cannot be class-wide.
4359 -- Use base type to exclude access_to_subprogram cases.
4366 and then
4371 -- Disable these checks for call to imported C++ subprograms
4373 and then not
4377 then
4378 Error_Msg_N
4383 Error_Msg_NE
4388 Check_Aliased_Parameter;
4392 -- If it is a named association, treat the selector_name as a
4393 -- proper identifier, and mark the corresponding entity.
4397 -- Ignore reference in SPARK mode, as it refers to an entity not
4398 -- in scope at the point of reference, so the reference should
4399 -- be ignored for computing effects of subprograms.
4401 and then not GNATprove_Mode
4402 then
4415 -- The following checks are only relevant when SPARK_Mode is on as
4416 -- they are not standard Ada legality rule. Internally generated
4417 -- temporaries are ignored.
4422 then
4423 -- An effectively volatile object may act as an actual
4424 -- parameter when the corresponding formal is of a non-scalar
4425 -- volatile type.
4429 then
4432 -- An effectively volatile object may act as an actual
4433 -- parameter in a call to an instance of Unchecked_Conversion.
4438 else
4439 Error_Msg_N
4444 -- Detect an external variable with an enabled property that
4445 -- does not match the mode of the corresponding formal in a
4446 -- procedure call. Functions are not considered because they
4447 -- cannot have effectively volatile formal parameters in the
4448 -- first place.
4455 then
4468 -- A formal parameter of a specific tagged type whose related
4469 -- subprogram is subject to pragma Extensions_Visible with value
4470 -- "False" cannot act as an actual in a subprogram with value
4471 -- "True" (SPARK RM 6.1.7(3)).
4475 Extensions_Visible_True
4476 then
4477 Error_Msg_N
4480 Error_Msg_NE
4484 -- The actual parameter of a Ghost subprogram whose formal is of
4485 -- mode IN OUT or OUT must be a Ghost variable (SPARK RM 6.9(13)).
4492 then
4493 Error_Msg_NE
4499 else
4506 -- Case where actual is not present
4508 else
4509 Insert_Default;
4516 -----------------------
4517 -- Resolve_Allocator --
4518 -----------------------
4530 procedure Check_Allocator_Discrim_Accessibility
4533 -- Check that accessibility level associated with an access discriminant
4534 -- initialized in an allocator by the expression Disc_Exp is not deeper
4535 -- than the level of the allocator type Alloc_Typ. An error message is
4536 -- issued if this condition is violated. Specialized checks are done for
4537 -- the cases of a constraint expression which is an access attribute or
4538 -- an access discriminant.
4541 -- If the allocator is an actual in a call, it is allowed to be class-
4542 -- wide when the context is not because it is a controlling actual.
4544 -------------------------------------------
4545 -- Check_Allocator_Discrim_Accessibility --
4546 -------------------------------------------
4548 procedure Check_Allocator_Discrim_Accessibility
4551 is
4552 begin
4555 then
4556 Error_Msg_N
4559 -- When the expression is an Access attribute the level of the prefix
4560 -- object must not be deeper than that of the allocator's type.
4564 Attribute_Access
4567 then
4568 Error_Msg_N
4570 Disc_Exp);
4572 -- When the expression is an access discriminant the check is against
4573 -- the level of the prefix object.
4579 then
4580 Error_Msg_N
4582 Disc_Exp);
4584 -- All other cases are legal
4586 else
4591 ----------------------------
4592 -- In_Dispatching_Context --
4593 ----------------------------
4598 begin
4604 -- Start of processing for Resolve_Allocator
4606 begin
4607 -- Replace general access with specific type
4617 -- For qualified expression, resolve the expression using the given
4618 -- subtype (nothing to do for type mark, subtype indication)
4623 and then not In_Dispatching_Context
4624 then
4625 Error_Msg_N
4633 -- A qualified expression requires an exact match of the type.
4634 -- Class-wide matching is not allowed.
4639 then
4643 -- Calls to build-in-place functions are not currently supported in
4644 -- allocators for access types associated with a simple storage pool.
4645 -- Supporting such allocators may require passing additional implicit
4646 -- parameters to build-in-place functions (or a significant revision
4647 -- of the current b-i-p implementation to unify the handling for
4648 -- multiple kinds of storage pools). ???
4652 then
4653 declare
4656 begin
4658 and then
4659 Present (Get_Rep_Pragma
4661 then
4662 Error_Msg_N
4669 -- A special accessibility check is needed for allocators that
4670 -- constrain access discriminants. The level of the type of the
4671 -- expression used to constrain an access discriminant cannot be
4672 -- deeper than the type of the allocator (in contrast to access
4673 -- parameters, where the level of the actual can be arbitrary).
4675 -- We can't use Valid_Conversion to perform this check because in
4676 -- general the type of the allocator is unrelated to the type of
4677 -- the access discriminant.
4681 then
4688 then
4691 -- Get the first component expression of the aggregate
4701 else
4705 else
4724 else
4729 else
4738 -- For a subtype mark or subtype indication, freeze the subtype
4740 else
4744 Error_Msg_N
4748 -- A special accessibility check is needed for allocators that
4749 -- constrain access discriminants. The level of the type of the
4750 -- expression used to constrain an access discriminant cannot be
4751 -- deeper than the type of the allocator (in contrast to access
4752 -- parameters, where the level of the actual can be arbitrary).
4753 -- We can't use Valid_Conversion to perform this check because
4754 -- in general the type of the allocator is unrelated to the type
4755 -- of the access discriminant.
4760 then
4770 else
4784 -- Ada 2005 (AI-344): A class-wide allocator requires an accessibility
4785 -- check that the level of the type of the created object is not deeper
4786 -- than the level of the allocator's access type, since extensions can
4787 -- now occur at deeper levels than their ancestor types. This is a
4788 -- static accessibility level check; a run-time check is also needed in
4789 -- the case of an initialized allocator with a class-wide argument (see
4790 -- Expand_Allocator_Expression).
4794 then
4795 declare
4798 begin
4803 else
4809 then
4812 Error_Msg_N
4821 -- Do not apply Ada 2005 accessibility checks on a class-wide
4822 -- allocator if the type given in the allocator is a formal
4823 -- type. A run-time check will be performed in the instance.
4833 -- Check for allocation from an empty storage pool
4838 -- If the context is an unchecked conversion, as may happen within an
4839 -- inlined subprogram, the allocator is being resolved with its own
4840 -- anonymous type. In that case, if the target type has a specific
4841 -- storage pool, it must be inherited explicitly by the allocator type.
4845 then
4846 Set_Associated_Storage_Pool
4854 -- Check that an allocator with task parts isn't for a nested access
4855 -- type when restriction No_Task_Hierarchy applies.
4859 then
4863 -- An illegal allocator may be rewritten as a raise Program_Error
4864 -- statement.
4868 -- An anonymous access discriminant is the definition of a
4869 -- coextension.
4873 N_Discriminant_Specification
4874 then
4875 declare
4879 begin
4882 -- Ada 2012 AI05-0052: If the designated type of the allocator
4883 -- is limited, then the allocator shall not be used to define
4884 -- the value of an access discriminant unless the discriminated
4885 -- type is immutably limited.
4890 then
4891 Error_Msg_N
4897 -- Avoid marking an allocator as a dynamic coextension if it is
4898 -- within a static construct.
4904 -- Cleanup for potential static coextensions
4906 else
4912 -- Report a simple error: if the designated object is a local task,
4913 -- its body has not been seen yet, and its activation will fail an
4914 -- elaboration check.
4921 then
4927 -- Ada 2012 (AI05-0111-3): Detect an attempt to allocate a task or a
4928 -- type with a task component on a subpool. This action must raise
4929 -- Program_Error at runtime.
4935 then
4947 ---------------------------
4948 -- Resolve_Arithmetic_Op --
4949 ---------------------------
4951 -- Used for resolving all arithmetic operators except exponentiation
4962 -- We do the resolution using the base type, because intermediate values
4963 -- in expressions always are of the base type, not a subtype of it.
4966 -- Returns True if N is in a context that expects "any real type"
4969 -- Return True iff given type is Integer or universal real/integer
4972 -- Choose type of integer literal in fixed-point operation to conform
4973 -- to available fixed-point type. T is the type of the other operand,
4974 -- which is needed to determine the expected type of N.
4977 -- Set operand type to T if universal
4979 -------------------------------
4980 -- Expected_Type_Is_Any_Real --
4981 -------------------------------
4984 begin
4985 -- N is the expression after "delta" in a fixed_point_definition;
4986 -- see RM-3.5.9(6):
4989 N_Decimal_Fixed_Point_Definition,
4991 -- N is one of the bounds in a real_range_specification;
4992 -- see RM-3.5.7(5):
4994 N_Real_Range_Specification,
4996 -- N is the expression of a delta_constraint;
4997 -- see RM-J.3(3):
4999 N_Delta_Constraint);
5002 -----------------------------
5003 -- Is_Integer_Or_Universal --
5004 -----------------------------
5011 begin
5017 else
5023 then
5034 ----------------------------
5035 -- Set_Mixed_Mode_Operand --
5036 ----------------------------
5042 begin
5045 -- A universal integer literal is resolved as standard integer
5046 -- except in the case of a fixed-point result, where we leave it
5047 -- as universal (to be handled by Exp_Fixd later on)
5051 else
5059 then
5060 -- A universal real can appear in a fixed-type context. We resolve
5061 -- the literal with that context, even though this might raise an
5062 -- exception prematurely (the other operand may be zero).
5069 then
5070 -- Integer arg in mixed-mode operation. Resolve with universal
5071 -- type, in case preference rule must be applied.
5077 then
5078 -- Not a mixed-mode operation, resolve with context
5084 -- N may itself be a mixed-mode operation, so use context type
5091 then
5092 -- Must be (fixed * fixed) operation, operand must have one
5093 -- compatible interpretation.
5100 then
5101 -- C * F(X) in a fixed context, where C is a real literal or a
5102 -- fixed-point expression. F must have either a fixed type
5103 -- interpretation or an integer interpretation, but not both.
5110 else
5117 else
5125 -- Reanalyze the literal with the fixed type of the context. If
5126 -- context is Universal_Fixed, we are within a conversion, leave
5127 -- the literal as a universal real because there is no usable
5128 -- fixed type, and the target of the conversion plays no role in
5129 -- the resolution.
5131 declare
5135 begin
5138 else
5144 then
5146 else
5154 else
5159 ----------------------
5160 -- Set_Operand_Type --
5161 ----------------------
5164 begin
5167 then
5172 -- Start of processing for Resolve_Arithmetic_Op
5174 begin
5179 then
5183 -- Special-case for mixed-mode universal expressions or fixed point type
5184 -- operation: each argument is resolved separately. The same treatment
5185 -- is required if one of the operands of a fixed point operation is
5186 -- universal real, since in this case we don't do a conversion to a
5187 -- specific fixed-point type (instead the expander handles the case).
5189 -- Set the type of the node to its universal interpretation because
5190 -- legality checks on an exponentiation operand need the context.
5195 then
5206 or else
5209 then
5214 -- If context is a fixed type and one operand is integer, the other
5215 -- is resolved with the type of the context.
5220 then
5227 then
5231 else
5236 -- Check the rule in RM05-4.5.5(19.1/2) disallowing universal_fixed
5237 -- multiplying operators from being used when the expected type is
5238 -- also universal_fixed. Note that B_Typ will be Universal_Fixed in
5239 -- some cases where the expected type is actually Any_Real;
5240 -- Expected_Type_Is_Any_Real takes care of that case.
5244 then
5248 N_Unchecked_Type_Conversion)
5249 then
5256 else
5259 and then not
5261 N_Unchecked_Type_Conversion)
5262 then
5263 Error_Msg_N
5268 -- The expected type is "any real type" in contexts like
5270 -- type T is delta <universal_fixed-expression> ...
5272 -- in which case we need to set the type to Universal_Real
5273 -- so that static expression evaluation will work properly.
5277 else
5287 then
5292 -- If no previous errors, this is only possible if one operand is
5293 -- overloaded and the context is universal. Resolve as such.
5298 else
5300 and then
5302 then
5306 -- If the context is Universal_Fixed and the operands are also
5307 -- universal fixed, this is an error, unless there is only one
5308 -- applicable fixed_point type (usually Duration).
5316 else
5321 else
5326 -- If one of the arguments was resolved to a non-universal type.
5327 -- label the result of the operation itself with the same type.
5328 -- Do the same for the universal argument, if any.
5340 -- In SPARK, a multiplication or division with operands of fixed point
5341 -- types must be qualified or explicitly converted to identify the
5342 -- result type.
5347 and then
5349 then
5350 Check_SPARK_05_Restriction
5354 -- Set overflow and division checking bit
5361 -- Give warning if explicit division by zero
5365 then
5371 or else
5374 then
5375 -- Specialize the warning message according to the operation.
5376 -- The following warnings are for the case
5381 -- For division, we have two cases, for float division
5382 -- of an unconstrained float type, on a machine where
5383 -- Machine_Overflows is false, we don't get an exception
5384 -- at run-time, but rather an infinity or Nan. The Nan
5385 -- case is pretty obscure, so just warn about infinities.
5389 and then not Machine_Overflows_On_Target
5390 then
5391 Error_Msg_N
5395 -- For all other cases, we get a Constraint_Error
5397 else
5398 Apply_Compile_Time_Constraint_Error
5404 Apply_Compile_Time_Constraint_Error
5409 Apply_Compile_Time_Constraint_Error
5413 -- Division by zero can only happen with division, rem,
5414 -- and mod operations.
5420 -- Otherwise just set the flag to check at run time
5422 else
5427 -- If Restriction No_Implicit_Conditionals is active, then it is
5428 -- violated if either operand can be negative for mod, or for rem
5429 -- if both operands can be negative.
5433 then
5434 declare
5441 -- Set if corresponding operand might be negative
5443 begin
5444 Determine_Range
5448 Determine_Range
5452 -- Check if we will be generating conditionals. There are two
5453 -- cases where that can happen, first for REM, the only case
5454 -- is largest negative integer mod -1, where the division can
5455 -- overflow, but we still have to give the right result. The
5456 -- front end generates a test for this annoying case. Here we
5457 -- just test if both operands can be negative (that's what the
5458 -- expander does, so we match its logic here).
5460 -- The second case is mod where either operand can be negative.
5461 -- In this case, the back end has to generate additional tests.
5464 or else
5466 then
5478 ------------------
5479 -- Resolve_Call --
5480 ------------------
5483 function Same_Or_Aliased_Subprograms
5486 -- Returns True if the subprogram entity S is the same as E or else
5487 -- S is an alias of E.
5489 ---------------------------------
5490 -- Same_Or_Aliased_Subprograms --
5491 ---------------------------------
5493 function Same_Or_Aliased_Subprograms
5496 is
5498 begin
5502 -- Local variables
5516 -- Start of processing for Resolve_Call
5518 begin
5519 -- The context imposes a unique interpretation with type Typ on a
5520 -- procedure or function call. Find the entity of the subprogram that
5521 -- yields the expected type, and propagate the corresponding formal
5522 -- constraints on the actuals. The caller has established that an
5523 -- interpretation exists, and emitted an error if not unique.
5525 -- First deal with the case of a call to an access-to-subprogram,
5526 -- dereference made explicit in Analyze_Call.
5532 else
5533 -- Find the interpretation whose type (a subprogram type) has a
5534 -- return type that is compatible with the context. Analysis of
5535 -- the node has established that one exists.
5554 -- If the prefix is not an entity, then resolve it
5560 -- For an indirect call, we always invalidate checks, since we do not
5561 -- know whether the subprogram is local or global. Yes we could do
5562 -- better here, e.g. by knowing that there are no local subprograms,
5563 -- but it does not seem worth the effort. Similarly, we kill all
5564 -- knowledge of current constant values.
5566 Kill_Current_Values;
5568 -- If this is a procedure call which is really an entry call, do
5569 -- the conversion of the procedure call to an entry call. Protected
5570 -- operations use the same circuitry because the name in the call
5571 -- can be an arbitrary expression with special resolution rules.
5576 then
5580 -- Kill checks and constant values, as above for indirect case
5581 -- Who knows what happens when another task is activated?
5583 Kill_Current_Values;
5586 -- Normal subprogram call with name established in Resolve
5592 -- Otherwise we must have the case of an overloaded call
5594 else
5597 -- Initialize Nam to prevent warning (we know it will be assigned
5598 -- in the loop below, but the compiler does not know that).
5618 then
5619 -- The prefix is a parameterless function call that returns an access
5620 -- to subprogram. If parameters are present in the current call, add
5621 -- add an explicit dereference. We use the base type here because
5622 -- within an instance these may be subtypes.
5624 -- The dereference is added either in Analyze_Call or here. Should
5625 -- be consolidated ???
5634 -- Check that a call to Current_Task does not occur in an entry body
5637 declare
5640 begin
5642 loop
5645 -- Exclude calls that occur within the default of a formal
5646 -- parameter of the entry, since those are evaluated outside
5647 -- of the body.
5654 then
5657 Error_Msg_NE
5671 -- Check that a procedure call does not occur in the context of the
5672 -- entry call statement of a conditional or timed entry call. Note that
5673 -- the case of a call to a subprogram renaming of an entry will also be
5674 -- rejected. The test for N not being an N_Entry_Call_Statement is
5675 -- defensive, covering the possibility that the processing of entry
5676 -- calls might reach this point due to later modifications of the code
5677 -- above.
5682 then
5686 -- Ada 2005 (AI-345): If a procedure_call_statement is used
5687 -- for a procedure_or_entry_call, the procedure_name or
5688 -- procedure_prefix of the procedure_call_statement shall denote
5689 -- an entry renamed by a procedure, or (a view of) a primitive
5690 -- subprogram of a limited interface whose first parameter is
5691 -- a controlling parameter.
5696 then
5697 Error_Msg_N
5702 -- If the SPARK_05 restriction is active, we are not allowed
5703 -- to have a call to a subprogram before we see its completion.
5708 -- Don't flag strange internal calls
5713 -- Only flag calls in extended main source
5718 -- Exclude enumeration literals from this processing
5721 then
5722 Check_SPARK_05_Restriction
5726 -- Check that this is not a call to a protected procedure or entry from
5727 -- within a protected function.
5731 -- Freeze the subprogram name if not in a spec-expression. Note that
5732 -- we freeze procedure calls as well as function calls. Procedure calls
5733 -- are not frozen according to the rules (RM 13.14(14)) because it is
5734 -- impossible to have a procedure call to a non-frozen procedure in
5735 -- pure Ada, but in the code that we generate in the expander, this
5736 -- rule needs extending because we can generate procedure calls that
5737 -- need freezing.
5739 -- In Ada 2012, expression functions may be called within pre/post
5740 -- conditions of subsequent functions or expression functions. Such
5741 -- calls do not freeze when they appear within generated bodies,
5742 -- (including the body of another expression function) which would
5743 -- place the freeze node in the wrong scope. An expression function
5744 -- is frozen in the usual fashion, by the appearance of a real body,
5745 -- or at the end of a declarative part.
5749 and then
5752 then
5756 -- For a predefined operator, the type of the result is the type imposed
5757 -- by context, except for a predefined operation on universal fixed.
5758 -- Otherwise The type of the call is the type returned by the subprogram
5759 -- being called.
5766 -- If the subprogram returns an array type, and the context requires the
5767 -- component type of that array type, the node is really an indexing of
5768 -- the parameterless call. Resolve as such. A pathological case occurs
5769 -- when the type of the component is an access to the array type. In
5770 -- this case the call is truly ambiguous.
5773 and then
5776 or else
5779 and then
5781 then
5782 declare
5787 begin
5790 then
5791 Error_Msg_N
5793 else
5796 -- The called entity may be an explicit dereference, in which
5797 -- case there is no entity to set.
5805 or else
5807 and then
5809 then
5812 -- Indexed call to a parameterless function
5814 Index_Node :=
5816 Prefix =>
5819 else
5820 -- An Ada 2005 prefixed call to a primitive operation
5821 -- whose first parameter is the prefix. This prefix was
5822 -- prepended to the parameter list, which is actually a
5823 -- list of indexes. Remove the prefix in order to build
5824 -- the proper indexed component.
5826 Index_Node :=
5828 Prefix =>
5831 Parameter_Associations =>
5832 New_List
5837 -- Preserve the parenthesis count of the node
5841 -- Since we are correcting a node classification error made
5842 -- by the parser, we call Replace rather than Rewrite.
5856 else
5860 -- In the case where the call is to an overloaded subprogram, Analyze
5861 -- calls Normalize_Actuals once per overloaded subprogram. Therefore in
5862 -- such a case Normalize_Actuals needs to be called once more to order
5863 -- the actuals correctly. Otherwise the call will have the ordering
5864 -- given by the last overloaded subprogram whether this is the correct
5865 -- one being called or not.
5872 -- In any case, call is fully resolved now. Reset Overload flag, to
5873 -- prevent subsequent overload resolution if node is analyzed again
5878 -- A Ghost entity must appear in a specific context
5884 -- If we are calling the current subprogram from immediately within its
5885 -- body, then that is the case where we can sometimes detect cases of
5886 -- infinite recursion statically. Do not try this in case restriction
5887 -- No_Recursion is in effect anyway, and do it only for source calls.
5892 -- Check violation of SPARK_05 restriction which does not permit
5893 -- a subprogram body to contain a call to the subprogram directly.
5897 then
5898 Check_SPARK_05_Restriction
5902 -- Issue warning for possible infinite recursion in the absence
5903 -- of the No_Recursion restriction.
5908 then
5909 -- Here we detected and flagged an infinite recursion, so we do
5910 -- not need to test the case below for further warnings. Also we
5911 -- are all done if we now have a raise SE node.
5917 -- If call is to immediately containing subprogram, then check for
5918 -- the case of a possible run-time detectable infinite recursion.
5920 else
5924 -- Although in general case, recursion is not statically
5925 -- checkable, the case of calling an immediately containing
5926 -- subprogram is easy to catch.
5930 -- If the recursive call is to a parameterless subprogram,
5931 -- then even if we can't statically detect infinite
5932 -- recursion, this is pretty suspicious, and we output a
5933 -- warning. Furthermore, we will try later to detect some
5934 -- cases here at run time by expanding checking code (see
5935 -- Detect_Infinite_Recursion in package Exp_Ch6).
5937 -- If the recursive call is within a handler, do not emit a
5938 -- warning, because this is a common idiom: loop until input
5939 -- is correct, catch illegal input in handler and restart.
5945 then
5946 -- For the case of a procedure call. We give the message
5947 -- only if the call is the first statement in a sequence
5948 -- of statements, or if all previous statements are
5949 -- simple assignments. This is simply a heuristic to
5950 -- decrease false positives, without losing too many good
5951 -- warnings. The idea is that these previous statements
5952 -- may affect global variables the procedure depends on.
5953 -- We also exclude raise statements, that may arise from
5954 -- constraint checks and are probably unrelated to the
5955 -- intended control flow.
5959 then
5960 declare
5962 begin
5966 N_Raise_Constraint_Error)
5967 then
5976 -- Do not give warning if we are in a conditional context
5978 declare
5980 begin
5986 then
5991 -- Here warning is to be issued
6007 -- Check obsolescent reference to Ada.Characters.Handling subprogram
6011 -- If subprogram name is a predefined operator, it was given in
6012 -- functional notation. Replace call node with operator node, so
6013 -- that actuals can be resolved appropriately.
6021 then
6027 -- Create a transient scope if the resulting type requires it
6029 -- There are several notable exceptions:
6031 -- a) In init procs, the transient scope overhead is not needed, and is
6032 -- even incorrect when the call is a nested initialization call for a
6033 -- component whose expansion may generate adjust calls. However, if the
6034 -- call is some other procedure call within an initialization procedure
6035 -- (for example a call to Create_Task in the init_proc of the task
6036 -- run-time record) a transient scope must be created around this call.
6038 -- b) Enumeration literal pseudo-calls need no transient scope
6040 -- c) Intrinsic subprograms (Unchecked_Conversion and source info
6041 -- functions) do not use the secondary stack even though the return
6042 -- type may be unconstrained.
6044 -- d) Calls to a build-in-place function, since such functions may
6045 -- allocate their result directly in a target object, and cases where
6046 -- the result does get allocated in the secondary stack are checked for
6047 -- within the specialized Exp_Ch6 procedures for expanding those
6048 -- build-in-place calls.
6050 -- e) If the subprogram is marked Inline_Always, then even if it returns
6051 -- an unconstrained type the call does not require use of the secondary
6052 -- stack. However, inlining will only take place if the body to inline
6053 -- is already present. It may not be available if e.g. the subprogram is
6054 -- declared in a child instance.
6056 -- If this is an initialization call for a type whose construction
6057 -- uses the secondary stack, and it is not a nested call to initialize
6058 -- a component, we do need to create a transient scope for it. We
6059 -- check for this by traversing the type in Check_Initialization_Call.
6065 then
6071 then
6074 elsif Expander_Active
6077 and then
6079 or else
6081 then
6084 -- If the call appears within the bounds of a loop, it will
6085 -- be rewritten and reanalyzed, nothing left to do here.
6092 and then not Within_Init_Proc
6093 then
6097 -- A protected function cannot be called within the definition of the
6098 -- enclosing protected type, unless it is part of a pre/postcondition
6099 -- on another protected operation.
6104 and then not In_Spec_Expression
6105 then
6106 Error_Msg_NE
6110 -- Propagate interpretation to actuals, and add default expressions
6111 -- where needed.
6116 -- Overloaded literals are rewritten as function calls, for purpose of
6117 -- resolution. After resolution, we can replace the call with the
6118 -- literal itself.
6124 -- Avoid validation, since it is a static function call
6130 -- If the subprogram is not global, then kill all saved values and
6131 -- checks. This is a bit conservative, since in many cases we could do
6132 -- better, but it is not worth the effort. Similarly, we kill constant
6133 -- values. However we do not need to do this for internal entities
6134 -- (unless they are inherited user-defined subprograms), since they
6135 -- are not in the business of molesting local values.
6137 -- If the flag Suppress_Value_Tracking_On_Calls is set, then we also
6138 -- kill all checks and values for calls to global subprograms. This
6139 -- takes care of the case where an access to a local subprogram is
6140 -- taken, and could be passed directly or indirectly and then called
6141 -- from almost any context.
6143 -- Note: we do not do this step till after resolving the actuals. That
6144 -- way we still take advantage of the current value information while
6145 -- scanning the actuals.
6147 -- We suppress killing values if we are processing the nodes associated
6148 -- with N_Freeze_Entity nodes. Otherwise the declaration of a tagged
6149 -- type kills all the values as part of analyzing the code that
6150 -- initializes the dispatch tables.
6154 or else Suppress_Value_Tracking_On_Call
6159 then
6160 Kill_Current_Values;
6163 -- If we are warning about unread OUT parameters, this is the place to
6164 -- set Last_Assignment for OUT and IN OUT parameters. We have to do this
6165 -- after the above call to Kill_Current_Values (since that call clears
6166 -- the Last_Assignment field of all local variables).
6171 then
6172 declare
6176 begin
6186 then
6196 -- If the subprogram is a primitive operation, check whether or not
6197 -- it is a correct dispatching call.
6201 then
6206 and then not In_Instance
6207 then
6211 -- If this is a dispatching call, generate the appropriate reference,
6212 -- for better source navigation in GPS.
6216 then
6219 -- Normal case, not a dispatching call: generate a call reference
6221 else
6229 -- Check for violation of restriction No_Specific_Termination_Handlers
6230 -- and warn on a potentially blocking call to Abort_Task.
6234 or else
6236 then
6243 -- A call to Ada.Real_Time.Timing_Events.Set_Handler to set a relative
6244 -- timing event violates restriction No_Relative_Delay (AI-0211). We
6245 -- need to check the second argument to determine whether it is an
6246 -- absolute or relative timing event.
6251 then
6255 -- Issue an error for a call to an eliminated subprogram. This routine
6256 -- will not perform the check if the call appears within a default
6257 -- expression.
6261 -- In formal mode, the primitive operations of a tagged type or type
6262 -- extension do not include functions that return the tagged type.
6268 then
6272 -- Implement rule in 12.5.1 (23.3/2): In an instance, if the actual is
6273 -- class-wide and the call dispatches on result in a context that does
6274 -- not provide a tag, the call raises Program_Error.
6277 and then In_Instance
6282 then
6283 -- Verify that none of the formals are controlling
6285 declare
6289 begin
6311 -- Check for calling a function with OUT or IN OUT parameter when the
6312 -- calling context (us right now) is not Ada 2012, so does not allow
6313 -- OUT or IN OUT parameters in function calls. Functions declared in
6314 -- a predefined unit are OK, as they may be called indirectly from a
6315 -- user-declared instantiation.
6321 then
6326 -- Check the dimensions of the actuals in the call. For function calls,
6327 -- propagate the dimensions from the returned type to N.
6331 -- All done, evaluate call and deal with elaboration issues
6336 -- In GNATprove mode, expansion is disabled, but we want to inline some
6337 -- subprograms to facilitate formal verification. Indirect calls through
6338 -- a subprogram type or within a generic cannot be inlined. Inlining is
6339 -- performed only for calls subject to SPARK_Mode on.
6341 if GNATprove_Mode
6344 and then not Inside_A_Generic
6345 then
6352 -- Nothing to do if the subprogram is not eligible for inlining in
6353 -- GNATprove mode.
6357 then
6360 -- Calls cannot be inlined inside assertions, as GNATprove treats
6361 -- assertions as logic expressions.
6368 -- Calls cannot be inlined inside default expressions
6375 -- Inlining should not be performed during pre-analysis
6379 -- With the one-pass inlining technique, a call cannot be
6380 -- inlined if the corresponding body has not been seen yet.
6383 Error_Msg_NE
6388 -- Nothing to do if there is no body to inline, indicating that
6389 -- the subprogram is not suitable for inlining in GNATprove
6390 -- mode.
6395 -- Calls cannot be inlined inside potentially unevaluated
6396 -- expressions, as this would create complex actions inside
6397 -- expressions, that are not handled by GNATprove.
6401 Error_Msg_N
6405 -- Otherwise, inline the call
6407 else
6417 -----------------------------
6418 -- Resolve_Case_Expression --
6419 -----------------------------
6425 begin
6432 -- Apply RM 4.5.7 (17/3): whether the expression is statically or
6433 -- dynamically tagged must be known statically.
6453 -------------------------------
6454 -- Resolve_Character_Literal --
6455 -------------------------------
6461 begin
6462 -- Verify that the character does belong to the type of the context
6467 -- Wide_Wide_Character literals must always be defined, since the set
6468 -- of wide wide character literals is complete, i.e. if a character
6469 -- literal is accepted by the parser, then it is OK for wide wide
6470 -- character (out of range character literals are rejected).
6475 -- Always accept character literal for type Any_Character, which
6476 -- occurs in error situations and in comparisons of literals, both
6477 -- of which should accept all literals.
6482 -- For Standard.Character or a type derived from it, check that the
6483 -- literal is in range.
6490 -- For Standard.Wide_Character or a type derived from it, check that the
6491 -- literal is in range.
6498 -- For Standard.Wide_Wide_Character or a type derived from it, we
6499 -- know the literal is in range, since the parser checked.
6504 -- If the entity is already set, this has already been resolved in a
6505 -- generic context, or comes from expansion. Nothing else to do.
6510 -- Otherwise we have a user defined character type, and we can use the
6511 -- standard visibility mechanisms to locate the referenced entity.
6513 else
6526 -- If we fall through, then the literal does not match any of the
6527 -- entries of the enumeration type. This isn't just a constraint error
6528 -- situation, it is an illegality (see RM 4.2).
6530 Error_Msg_NE
6534 ---------------------------
6535 -- Resolve_Comparison_Op --
6536 ---------------------------
6538 -- Context requires a boolean type, and plays no role in resolution.
6539 -- Processing identical to that for equality operators. The result type is
6540 -- the base type, which matters when pathological subtypes of booleans with
6541 -- limited ranges are used.
6548 begin
6549 -- If this is an intrinsic operation which is not predefined, use the
6550 -- types of its declared arguments to resolve the possibly overloaded
6551 -- operands. Otherwise the operands are unambiguous and specify the
6552 -- expected type.
6557 else
6568 -- Skip remaining processing if already set to Any_Type
6574 -- Deal with other error cases
6578 T = Any_Character
6579 then
6582 else
6590 -- Resolve the operands if types OK
6599 -- In SPARK, ordering operators <, <=, >, >= are not defined for Boolean
6600 -- types or array types except String.
6603 Check_SPARK_05_Restriction
6608 then
6609 Check_SPARK_05_Restriction
6613 -- Check comparison on unordered enumeration
6617 Error_Msg_NE
6622 -- Evaluate the relation (note we do this after the above check since
6623 -- this Eval call may change N to True/False.
6629 -----------------------------------------
6630 -- Resolve_Discrete_Subtype_Indication --
6631 -----------------------------------------
6633 procedure Resolve_Discrete_Subtype_Indication
6636 is
6640 begin
6648 else
6658 Error_Msg_NE
6661 -- Rewrite the constraint as a range of Typ
6662 -- to allow compilation to proceed further.
6674 else
6678 -- Additionally, we must check that the bounds are compatible
6679 -- with the given subtype, which might be different from the
6680 -- type of the context.
6684 -- ??? If the above check statically detects a Constraint_Error
6685 -- it replaces the offending bound(s) of the range R with a
6686 -- Constraint_Error node. When the itype which uses these bounds
6687 -- is frozen the resulting call to Duplicate_Subexpr generates
6688 -- a new temporary for the bounds.
6690 -- Unfortunately there are other itypes that are also made depend
6691 -- on these bounds, so when Duplicate_Subexpr is called they get
6692 -- a forward reference to the newly created temporaries and Gigi
6693 -- aborts on such forward references. This is probably sign of a
6694 -- more fundamental problem somewhere else in either the order of
6695 -- itype freezing or the way certain itypes are constructed.
6697 -- To get around this problem we call Remove_Side_Effects right
6698 -- away if either bounds of R are a Constraint_Error.
6700 declare
6704 begin
6720 -------------------------
6721 -- Resolve_Entity_Name --
6722 -------------------------
6724 -- Used to resolve identifiers and expanded names
6727 function Is_Assignment_Or_Object_Expression
6730 -- Determine whether node Context denotes an assignment statement or an
6731 -- object declaration whose expression is node Expr.
6733 function Is_OK_Volatile_Context
6736 -- Determine whether node Context denotes a "non-interfering context"
6737 -- (as defined in SPARK RM 7.1.3(13)) where volatile reference Obj_Ref
6738 -- can safely reside.
6740 ----------------------------------------
6741 -- Is_Assignment_Or_Object_Expression --
6742 ----------------------------------------
6744 function Is_Assignment_Or_Object_Expression
6747 is
6748 begin
6750 N_Object_Declaration)
6752 then
6755 -- Check whether a construct that yields a name is the expression of
6756 -- an assignment statement or an object declaration.
6759 N_Explicit_Dereference,
6760 N_Indexed_Component,
6761 N_Selected_Component,
6762 N_Slice)
6764 or else
6766 N_Unchecked_Type_Conversion)
6768 then
6769 return
6770 Is_Assignment_Or_Object_Expression
6774 -- Otherwise the context is not an assignment statement or an object
6775 -- declaration.
6777 else
6782 ----------------------------
6783 -- Is_OK_Volatile_Context --
6784 ----------------------------
6786 function Is_OK_Volatile_Context
6789 is
6791 -- Determine whether an arbitrary node appears in a check node
6794 -- Determine whether an arbitrary node appears in a procedure call
6796 ------------------
6797 -- Within_Check --
6798 ------------------
6803 begin
6804 -- Climb the parent chain looking for a check node
6811 -- Prevent the search from going too far
6823 ---------------------------
6824 -- Within_Procedure_Call --
6825 ---------------------------
6830 begin
6831 -- Climb the parent chain looking for a procedure call
6838 -- Prevent the search from going too far
6850 -- Start of processing for Is_OK_Volatile_Context
6852 begin
6853 -- The volatile object appears on either side of an assignment
6858 -- The volatile object is part of the initialization expression of
6859 -- another object. Ensure that the climb of the parent chain came
6860 -- from the expression side and not from the name side.
6865 then
6868 -- The volatile object appears as an actual parameter in a call to an
6869 -- instance of Unchecked_Conversion whose result is renamed.
6874 then
6877 -- The volatile object appears as the prefix of a name occurring
6878 -- in a non-interfering context.
6881 N_Explicit_Dereference,
6882 N_Indexed_Component,
6883 N_Selected_Component,
6884 N_Slice)
6886 and then Is_OK_Volatile_Context
6889 then
6892 -- The volatile object appears as the expression of a type conversion
6893 -- occurring in a non-interfering context.
6896 N_Unchecked_Type_Conversion)
6898 and then Is_OK_Volatile_Context
6901 then
6904 -- Allow references to volatile objects in various checks. This is
6905 -- not a direct SPARK 2014 requirement.
6910 -- Assume that references to effectively volatile objects that appear
6911 -- as actual parameters in a procedure call are always legal. A full
6912 -- legality check is done when the actuals are resolved.
6917 -- Otherwise the context is not suitable for an effectively volatile
6918 -- object.
6920 else
6925 -- Local variables
6930 -- Start of processing for Resolve_Entity_Name
6932 begin
6933 -- If garbage from errors, set to Any_Type and return
6940 -- Replace named numbers by corresponding literals. Note that this is
6941 -- the one case where Resolve_Entity_Name must reset the Etype, since
6942 -- it is currently marked as universal.
6952 -- For enumeration literals, we need to make sure that a proper style
6953 -- check is done, since such literals are overloaded, and thus we did
6954 -- not do a style check during the first phase of analysis.
6960 -- Case of subtype name appearing as an operand in expression
6964 -- Allow use of subtype if it is a concurrent type where we are
6965 -- currently inside the body. This will eventually be expanded into a
6966 -- call to Self (for tasks) or _object (for protected objects). Any
6967 -- other use of a subtype is invalid.
6971 then
6974 -- Any other use is an error
6976 else
6977 Error_Msg_N
6981 -- Check discriminant use if entity is discriminant in current scope,
6982 -- i.e. discriminant of record or concurrent type currently being
6983 -- analyzed. Uses in corresponding body are unrestricted.
6988 then
6991 -- A parameterless generic function cannot appear in a context that
6992 -- requires resolution.
6997 -- In Ada 83 an OUT parameter cannot be read
7002 or else Is_Assignment_Or_Object_Expression
7005 then
7009 -- An effectively volatile OUT parameter cannot be read
7010 -- (SPARK RM 7.1.3(11)).
7014 then
7018 -- In all other cases, just do the possible static evaluation
7020 else
7021 -- A deferred constant that appears in an expression must have a
7022 -- completion, unless it has been removed by in-place expansion of
7023 -- an aggregate.
7029 and then not In_Spec_Expression
7031 then
7035 then
7037 else
7038 Error_Msg_N (
7048 -- When the entity appears in a parameter association, retrieve the
7049 -- related subprogram call.
7055 -- The following checks are only relevant when SPARK_Mode is on as they
7056 -- are not standard Ada legality rules. An effectively volatile object
7057 -- subject to enabled properties Async_Writers or Effective_Reads must
7058 -- appear in a specific context.
7066 then
7067 -- The effectively volatile objects appears in a "non-interfering
7068 -- context" as defined in SPARK RM 7.1.3(13).
7073 -- Otherwise the context causes a side effect with respect to the
7074 -- effectively volatile object.
7076 else
7077 SPARK_Msg_N
7083 -- A Ghost entity must appear in a specific context
7089 -- In SPARK mode, need to check possible elaboration issues
7096 -------------------
7097 -- Resolve_Entry --
7098 -------------------
7110 -- If the bounds of the entry family being called depend on task
7111 -- discriminants, build a new index subtype where a discriminant is
7112 -- replaced with the value of the discriminant of the target task.
7113 -- The target task is the prefix of the entry name in the call.
7115 -----------------------
7116 -- Actual_Index_Type --
7117 -----------------------
7127 -- If the bound is given by a discriminant, replace with a reference
7128 -- to the discriminant of the same name in the target task. If the
7129 -- entry name is the target of a requeue statement and the entry is
7130 -- in the current protected object, the bound to be used is the
7131 -- discriminal of the object (see Apply_Range_Checks for details of
7132 -- the transformation).
7134 -----------------------------
7135 -- Actual_Discriminant_Ref --
7136 -----------------------------
7142 begin
7147 then
7153 then
7154 -- Note: here Bound denotes a discriminant of the corresponding
7155 -- record type tskV, whose discriminal is a formal of the
7156 -- init-proc tskVIP. What we want is the body discriminal,
7157 -- which is associated to the discriminant of the original
7158 -- concurrent type tsk.
7160 return New_Occurrence_Of
7163 else
7164 Ref :=
7174 -- Start of processing for Actual_Index_Type
7176 begin
7179 then
7182 else
7196 -- Start of processing of Resolve_Entry
7198 begin
7199 -- Find name of entry being called, and resolve prefix of name with its
7200 -- own type. The prefix can be overloaded, and the name and signature of
7201 -- the entry must be taken into account.
7205 -- Case of dealing with entry family within the current tasks
7209 else
7215 -- Entry call to an entry (or entry family) in the current task. This
7216 -- is legal even though the task will deadlock. Rewrite as call to
7217 -- current task.
7219 -- This can also be a call to an entry in an enclosing task. If this
7220 -- is a single task, we have to retrieve its name, because the scope
7221 -- of the entry is the task type, not the object. If the enclosing
7222 -- task is a task type, the identity of the task is given by its own
7223 -- self variable.
7225 -- Finally this can be a requeue on an entry of the same task or
7226 -- protected object.
7233 then
7234 -- S is an enclosing task or protected object. The concurrent
7235 -- declaration has been converted into a type declaration, and
7236 -- the object itself has an object declaration that follows
7237 -- the type in the same declarative part.
7249 -- Call to current task. Will be transformed into call to Self
7256 New_N :=
7259 Selector_Name =>
7266 then
7267 -- Use the entry name (which must be unique at this point) to find
7268 -- the prefix that returns the corresponding task/protected type.
7270 declare
7276 begin
7298 -- Up to this point the expression could have been the actual in a
7299 -- simple entry call, and be given by a named association.
7303 else
7309 ------------------------
7310 -- Resolve_Entry_Call --
7311 ------------------------
7323 begin
7324 -- We kill all checks here, because it does not seem worth the effort to
7325 -- do anything better, an entry call is a big operation.
7327 Kill_All_Checks;
7329 -- Processing of the name is similar for entry calls and protected
7330 -- operation calls. Once the entity is determined, we can complete
7331 -- the resolution of the actuals.
7333 -- The selector may be overloaded, in the case of a protected object
7334 -- with overloaded functions. The type of the context is used for
7335 -- resolution.
7340 then
7341 declare
7345 begin
7364 -- Simple entry call
7372 -- Call to member of entry family
7379 -- We cannot in general check the maximum depth of protected entry calls
7380 -- at compile time. But we can tell that any protected entry call at all
7381 -- violates a specified nesting depth of zero.
7387 -- Use context type to disambiguate a protected function that can be
7388 -- called without actuals and that returns an array type, and where the
7389 -- argument list may be an indexing of the returned value.
7394 and then
7400 and then
7401 Covers
7404 then
7405 declare
7408 begin
7409 Index_Node :=
7411 Prefix =>
7415 -- Since we are correcting a node classification error made by the
7416 -- parser, we call Replace rather than Rewrite.
7429 then
7430 -- Rewrite as call to the precondition wrapper, adding the task
7431 -- object to the list of actuals. If the call is to a member of an
7432 -- entry family, include the index as well.
7434 declare
7438 begin
7447 New_Call :=
7449 Name =>
7454 -- Preanalyze and resolve new call. Current procedure is called
7455 -- from Resolve_Call, after which expansion will take place.
7462 -- The operation name may have been overloaded. Order the actuals
7463 -- according to the formals of the resolved entity, and set the return
7464 -- type to that of the operation.
7475 -- Create a call reference to the entry
7483 -- Verify that a procedure call cannot masquerade as an entry
7484 -- call where an entry call is expected.
7489 then
7494 then
7499 then
7504 -- After resolution, entry calls and protected procedure calls are
7505 -- changed into entry calls, for expansion. The structure of the node
7506 -- does not change, so it can safely be done in place. Protected
7507 -- function calls must keep their structure because they are
7508 -- subexpressions.
7512 -- A protected operation that is not a function may modify the
7513 -- corresponding object, and cannot apply to a constant. If this
7514 -- is an internal call, the prefix is the type itself.
7520 then
7521 Error_Msg_N
7523 Entry_Name);
7537 -- Protected functions can return on the secondary stack, in which
7538 -- case we must trigger the transient scope mechanism.
7540 elsif Expander_Active
7542 then
7547 -------------------------
7548 -- Resolve_Equality_Op --
7549 -------------------------
7551 -- Both arguments must have the same type, and the boolean context does
7552 -- not participate in the resolution. The first pass verifies that the
7553 -- interpretation is not ambiguous, and the type of the left argument is
7554 -- correctly set, or is Any_Type in case of ambiguity. If both arguments
7555 -- are strings or aggregates, allocators, or Null, they are ambiguous even
7556 -- though they carry a single (universal) type. Diagnose this case here.
7564 -- The resolution rule for if expressions requires that each such must
7565 -- have a unique type. This means that if several dependent expressions
7566 -- are of a non-null anonymous access type, and the context does not
7567 -- impose an expected type (as can be the case in an equality operation)
7568 -- the expression must be rejected.
7571 -- Attempt to explain the nature of a redundant comparison with True. If
7572 -- the expression N is too complex, this routine issues a general error
7573 -- message.
7576 -- In the case of allocators and access attributes, the context must
7577 -- provide an indication of the specific access type to be used. If
7578 -- one operand is of such a "generic" access type, check whether there
7579 -- is a specific visible access type that has the same designated type.
7580 -- This is semantically dubious, and of no interest to any real code,
7581 -- but c48008a makes it all worthwhile.
7583 -------------------------
7584 -- Check_If_Expression --
7585 -------------------------
7591 begin
7598 then
7604 ------------------------
7605 -- Explain_Redundancy --
7606 ------------------------
7613 begin
7616 -- Strip the operand down to an entity
7618 loop
7621 else
7626 -- The construct denotes an entity
7631 -- Do not generate an error message when the comparison is done
7632 -- against the enumeration literal Standard.True.
7636 -- Build a customized error message
7663 -- The construct is too complex to disect, issue a general message
7665 else
7670 -----------------------------
7671 -- Find_Unique_Access_Type --
7672 -----------------------------
7679 begin
7681 E_Access_Attribute_Type)
7682 then
7686 E_Access_Attribute_Type)
7687 then
7689 else
7701 then
7714 -- Start of processing for Resolve_Equality_Op
7716 begin
7727 T = Any_Character
7728 then
7731 else
7740 then
7749 -- If expressions must have a single type, and if the context does
7750 -- not impose one the dependent expressions cannot be anonymous
7751 -- access types.
7753 -- Why no similar processing for case expressions???
7757 E_Anonymous_Access_Subprogram_Type)
7759 E_Anonymous_Access_Subprogram_Type)
7760 then
7768 -- In SPARK, equality operators = and /= for array types other than
7769 -- String are only defined when, for each index position, the
7770 -- operands have equal static bounds.
7774 -- Protect call to Matching_Static_Array_Bounds to avoid costly
7775 -- operation if not needed.
7783 then
7784 Check_SPARK_05_Restriction
7789 -- If the unique type is a class-wide type then it will be expanded
7790 -- into a dispatching call to the predefined primitive. Therefore we
7791 -- check here for potential violation of such restriction.
7797 if Warn_On_Redundant_Constructs
7802 then
7803 Error_Msg_N -- CODEFIX
7813 -- If this is an inequality, it may be the implicit inequality
7814 -- created for a user-defined operation, in which case the corres-
7815 -- ponding equality operation is not intrinsic, and the operation
7816 -- cannot be constant-folded. Else fold.
7821 or else Is_Intrinsic_Subprogram
7823 then
7829 then
7833 -- Ada 2005: If one operand is an anonymous access type, convert the
7834 -- other operand to it, to ensure that the underlying types match in
7835 -- the back-end. Same for access_to_subprogram, and the conversion
7836 -- verifies that the types are subtype conformant.
7838 -- We apply the same conversion in the case one of the operands is a
7839 -- private subtype of the type of the other.
7841 -- Why the Expander_Active test here ???
7843 if Expander_Active
7844 and then
7846 E_Anonymous_Access_Subprogram_Type)
7848 then
7868 ----------------------------------
7869 -- Resolve_Explicit_Dereference --
7870 ----------------------------------
7878 -- The candidate prefix type, if overloaded
7883 begin
7887 -- A useful optimization: check whether the dereference denotes an
7888 -- element of a container, and if so rewrite it as a call to the
7889 -- corresponding Element function.
7891 -- Disabled for now, on advice of ARG. A more restricted form of the
7892 -- predicate might be acceptable ???
7894 -- if Is_Container_Element (N) then
7895 -- return;
7896 -- end if;
7900 -- Use the context type to select the prefix that has the correct
7901 -- designated type. Keep the first match, which will be the inner-
7902 -- most.
7909 then
7914 -- Remove access types that do not match, but preserve access
7915 -- to subprogram interpretations, in case a further dereference
7916 -- is needed (see below).
7929 else
7930 -- If no interpretation covers the designated type of the prefix,
7931 -- this is the pathological case where not all implementations of
7932 -- the prefix allow the interpretation of the node as a call. Now
7933 -- that the expected type is known, Remove other interpretations
7934 -- from prefix, rewrite it as a call, and resolve again, so that
7935 -- the proper call node is generated.
7946 New_N :=
7948 Name =>
7959 -- If not overloaded, resolve P with its own type
7961 else
7969 -- If the designated type is a packed unconstrained array type, and the
7970 -- explicit dereference is not in the context of an attribute reference,
7971 -- then we must compute and set the actual subtype, since it is needed
7972 -- by Gigi. The reason we exclude the attribute case is that this is
7973 -- handled fine by Gigi, and in fact we use such attributes to build the
7974 -- actual subtype. We also exclude generated code (which builds actual
7975 -- subtypes directly if they are needed).
7982 then
7986 -- Note: No Eval processing is required for an explicit dereference,
7987 -- because such a name can never be static.
7991 -------------------------------------
7992 -- Resolve_Expression_With_Actions --
7993 -------------------------------------
7996 begin
7999 -- If N has no actions, and its expression has been constant folded,
8000 -- then rewrite N as just its expression. Note, we can't do this in
8001 -- the general case of Is_Empty_List (Actions (N)) as this would cause
8002 -- Expression (N) to be expanded again.
8006 then
8011 ----------------------------------
8012 -- Resolve_Generalized_Indexing --
8013 ----------------------------------
8021 begin
8022 -- In ASIS mode, propagate the information about the indexes back to
8023 -- to the original indexing node. The generalized indexing is either
8024 -- a function call, or a dereference of one. The actuals include the
8025 -- prefix of the original node, which is the container expression.
8034 loop
8045 else
8051 ---------------------------
8052 -- Resolve_If_Expression --
8053 ---------------------------
8062 begin
8067 -- When the "then" expression is of a scalar subtype different from the
8068 -- result subtype, then insert a conversion to ensure the generation of
8069 -- a constraint check. The same is done for the else part below, again
8070 -- comparing subtypes rather than base types.
8074 then
8079 -- If ELSE expression present, just resolve using the determined type
8089 -- Apply RM 4.5.7 (17/3): whether the expression is statically or
8090 -- dynamically tagged must be known statically.
8095 then
8101 -- If no ELSE expression is present, root type must be Standard.Boolean
8102 -- and we provide a Standard.True result converted to the appropriate
8103 -- Boolean type (in case it is a derived boolean type).
8106 Else_Expr :=
8111 else
8120 -------------------------------
8121 -- Resolve_Indexed_Component --
8122 -------------------------------
8130 begin
8138 -- Use the context type to select the prefix that yields the correct
8139 -- component type.
8141 declare
8148 begin
8155 and then
8156 Covers
8159 then
8168 else
8174 else
8185 else
8192 -- If prefix is access type, dereference to get real array type.
8193 -- Note: we do not apply an access check because the expander always
8194 -- introduces an explicit dereference, and the check will happen there.
8200 -- If name was overloaded, set component type correctly now
8201 -- If a misplaced call to an entry family (which has no index types)
8202 -- return. Error will be diagnosed from calling context.
8206 else
8213 -- The prefix may have resolved to a string literal, in which case its
8214 -- etype has a special representation. This is only possible currently
8215 -- if the prefix is a static concatenation, written in functional
8216 -- notation.
8221 else
8228 else
8239 -- Do not generate the warning on suspicious index if we are analyzing
8240 -- package Ada.Tags; otherwise we will report the warning with the
8241 -- Prims_Ptr field of the dispatch table.
8244 or else not
8246 Ada_Tags)
8247 then
8252 -- If the array type is atomic, and the component is not atomic, then
8253 -- this is worth a warning, since we have a situation where the access
8254 -- to the component may cause extra read/writes of the atomic array
8255 -- object, or partial word accesses, which could be unexpected.
8261 and then Has_Atomic_Components
8264 then
8265 Error_Msg_N
8267 Error_Msg_N
8272 -----------------------------
8273 -- Resolve_Integer_Literal --
8274 -----------------------------
8277 begin
8282 --------------------------------
8283 -- Resolve_Intrinsic_Operator --
8284 --------------------------------
8293 -- If the operand is a literal, it cannot be the expression in a
8294 -- conversion. Use a qualified expression instead.
8296 ---------------------
8297 -- Convert_Operand --
8298 ---------------------
8304 begin
8306 Res :=
8312 else
8319 -- Start of processing for Resolve_Intrinsic_Operator
8321 begin
8322 -- We must preserve the original entity in a generic setting, so that
8323 -- the legality of the operation can be verified in an instance.
8338 -- If the result or operand types are private, rewrite with unchecked
8339 -- conversions on the operands and the result, to expose the proper
8340 -- underlying numeric type.
8345 then
8350 else
8371 then
8372 -- Add explicit conversion where needed, and save interpretations in
8373 -- case operands are overloaded.
8380 else
8386 else
8396 else
8401 --------------------------------------
8402 -- Resolve_Intrinsic_Unary_Operator --
8403 --------------------------------------
8405 procedure Resolve_Intrinsic_Unary_Operator
8408 is
8413 begin
8432 else
8437 ------------------------
8438 -- Resolve_Logical_Op --
8439 ------------------------
8444 begin
8447 -- Predefined operations on scalar types yield the base type. On the
8448 -- other hand, logical operations on arrays yield the type of the
8449 -- arguments (and the context).
8453 else
8457 -- The following test is required because the operands of the operation
8458 -- may be literals, in which case the resulting type appears to be
8459 -- compatible with a signed integer type, when in fact it is compatible
8460 -- only with modular types. If the context itself is universal, the
8461 -- operation is illegal.
8469 Error_Msg_N
8477 then
8481 -- Replace AND by AND THEN, or OR by OR ELSE, if Short_Circuit_And_Or
8482 -- is active and the result type is standard Boolean (do not mess with
8483 -- ops that return a nonstandard Boolean type, because something strange
8484 -- is going on).
8486 -- Note: you might expect this replacement to be done during expansion,
8487 -- but that doesn't work, because when the pragma Short_Circuit_And_Or
8488 -- is used, no part of the right operand of an "and" or "or" operator
8489 -- should be executed if the left operand would short-circuit the
8490 -- evaluation of the corresponding "and then" or "or else". If we left
8491 -- the replacement to expansion time, then run-time checks associated
8492 -- with such operands would be evaluated unconditionally, due to being
8493 -- before the condition prior to the rewriting as short-circuit forms
8494 -- during expansion.
8496 if Short_Circuit_And_Or
8499 then
8500 -- Mark the corresponding putative SCO operator as truly a logical
8501 -- (and short-circuit) operator.
8514 -- Case of OR changed to OR ELSE
8516 else
8524 -- Return now, since analysis of the rewritten ops will take care of
8525 -- other reference bookkeeping and expression folding.
8540 -- In SPARK, logical operations AND, OR and XOR for arrays are defined
8541 -- only when both operands have same static lower and higher bounds. Of
8542 -- course the types have to match, so only check if operands are
8543 -- compatible and the node itself has no errors.
8547 then
8548 declare
8552 begin
8553 -- Protect call to Matching_Static_Array_Bounds to avoid costly
8554 -- operation if not needed.
8561 then
8562 Check_SPARK_05_Restriction
8571 ---------------------------
8572 -- Resolve_Membership_Op --
8573 ---------------------------
8575 -- The context can only be a boolean type, and does not determine the
8576 -- arguments. Arguments should be unambiguous, but the preference rule for
8577 -- universal types applies.
8587 -- Analysis has determined a unique type for the left operand. Use it to
8588 -- resolve the disjuncts.
8590 ----------------------------
8591 -- Resolve_Set_Membership --
8592 ----------------------------
8598 begin
8599 -- If the left operand is overloaded, find type compatible with not
8600 -- overloaded alternative of the right operand.
8609 else
8614 -- Unclear how to resolve expression if all alternatives are also
8615 -- overloaded.
8621 else
8630 -- Alternative is an expression, a range
8631 -- or a subtype mark.
8635 then
8642 -- Check for duplicates for discrete case
8645 declare
8654 begin
8655 -- Loop checking duplicates. This is quadratic, but giant sets
8656 -- are unlikely in this context so it's a reasonable choice.
8663 N_Character_Literal)
8665 then
8683 -- Start of processing for Resolve_Membership_Op
8685 begin
8691 Resolve_Set_Membership;
8695 and then
8697 or else
8700 then
8703 -- Ada 2005 (AI-251): Support the following case:
8705 -- type I is interface;
8706 -- type T is tagged ...
8708 -- function Test (O : I'Class) is
8709 -- begin
8710 -- return O in T'Class.
8711 -- end Test;
8713 -- In this case we have nothing else to do. The membership test will be
8714 -- done at run time.
8721 then
8723 else
8727 -- If mixed-mode operations are present and operands are all literal,
8728 -- the only interpretation involves Duration, which is probably not
8729 -- the intention of the programmer.
8744 then
8750 else
8755 -- Here after resolving membership operation
8763 ------------------
8764 -- Resolve_Null --
8765 ------------------
8770 begin
8771 -- Handle restriction against anonymous null access values This
8772 -- restriction can be turned off using -gnatdj.
8774 -- Ada 2005 (AI-231): Remove restriction
8777 and then not Debug_Flag_J
8780 then
8781 -- In the common case of a call which uses an explicitly null value
8782 -- for an access parameter, give specialized error message.
8785 Error_Msg_N
8788 -- Standard message for all other cases (are there any?)
8790 else
8791 Error_Msg_N
8796 -- Ada 2005 (AI-231): Generate the null-excluding check in case of
8797 -- assignment to a null-excluding object
8802 then
8804 Insert_Action
8809 else
8816 -- In a distributed context, null for a remote access to subprogram may
8817 -- need to be replaced with a special record aggregate. In this case,
8818 -- return after having done the transformation.
8823 then
8827 -- The null literal takes its type from the context
8832 -----------------------
8833 -- Resolve_Op_Concat --
8834 -----------------------
8838 -- We wish to avoid deep recursion, because concatenations are often
8839 -- deeply nested, as in A&B&...&Z. Therefore, we walk down the left
8840 -- operands nonrecursively until we find something that is not a simple
8841 -- concatenation (A in this case). We resolve that, and then walk back
8842 -- up the tree following Parent pointers, calling Resolve_Op_Concat_Rest
8843 -- to do the rest of the work at each level. The Parent pointers allow
8844 -- us to avoid recursion, and thus avoid running out of memory. See also
8845 -- Sem_Ch4.Analyze_Concatenation, where a similar approach is used.
8850 begin
8851 -- The following code is equivalent to:
8853 -- Resolve_Op_Concat_First (NN, Typ);
8854 -- Resolve_Op_Concat_Arg (N, ...);
8855 -- Resolve_Op_Concat_Rest (N, Typ);
8857 -- where the Resolve_Op_Concat_Arg call recurses back here if the left
8858 -- operand is a concatenation.
8860 -- Walk down left operands
8862 loop
8871 -- Now (given the above example) NN is A&B and Op1 is A
8873 -- First resolve Op1 ...
8877 -- ... then walk NN back up until we reach N (where we started), calling
8878 -- Resolve_Op_Concat_Rest along the way.
8880 loop
8887 Check_SPARK_05_Restriction
8892 ---------------------------
8893 -- Resolve_Op_Concat_Arg --
8894 ---------------------------
8896 procedure Resolve_Op_Concat_Arg
8901 is
8905 begin
8907 if Is_Comp
8911 then
8913 else
8917 -- If both Array & Array and Array & Component are visible, there is a
8918 -- potential ambiguity that must be reported.
8923 then
8927 -- If the operation is user-defined and not overloaded use its
8928 -- profile. The operation may be a renaming, in which case it has
8929 -- been rewritten, and we want the original profile.
8934 then
8936 Etype
8940 -- Otherwise an aggregate may match both the array type and the
8941 -- component type.
8943 else
8948 else
8952 then
8953 declare
8958 begin
8963 -- Special-case the error message when the overloading is
8964 -- caused by a function that yields an array and can be
8965 -- called without parameters.
8970 Error_Msg_NE
8972 Error_Msg_NE
8976 else
8984 or else
8986 then
8987 Error_Msg_N -- CODEFIX
9005 else
9010 else
9014 -- Concatenation is restricted in SPARK: each operand must be either a
9015 -- string literal, the name of a string constant, a static character or
9016 -- string expression, or another concatenation. Arg cannot be a
9017 -- concatenation here as callers of Resolve_Op_Concat_Arg call it
9018 -- separately on each final operand, past concatenation operations.
9022 Check_SPARK_05_Restriction
9030 then
9031 Check_SPARK_05_Restriction
9035 -- Do not issue error on an operand that is neither a character nor a
9036 -- string, as the error is issued in Resolve_Op_Concat.
9038 else
9045 -----------------------------
9046 -- Resolve_Op_Concat_First --
9047 -----------------------------
9054 begin
9055 -- The parser folds an enormous sequence of concatenations of string
9056 -- literals into "" & "...", where the Is_Folded_In_Parser flag is set
9057 -- in the right operand. If the expression resolves to a predefined "&"
9058 -- operator, all is well. Otherwise, the parser's folding is wrong, so
9059 -- we give an error. See P_Simple_Expression in Par.Ch4.
9064 then
9079 ----------------------------
9080 -- Resolve_Op_Concat_Rest --
9081 ----------------------------
9087 begin
9096 -- If this is not a static concatenation, but the result is a string
9097 -- type (and not an array of strings) ensure that static string operands
9098 -- have their subtypes properly constructed.
9102 then
9108 ----------------------
9109 -- Resolve_Op_Expon --
9110 ----------------------
9115 begin
9116 -- Catch attempts to do fixed-point exponentiation with universal
9117 -- operands, which is a case where the illegality is not caught during
9118 -- normal operator analysis. This is not done in preanalysis mode
9119 -- since the tree is not fully decorated during preanalysis.
9130 then
9140 then
9147 then
9151 -- We do the resolution using the base type, because intermediate values
9152 -- in expressions are always of the base type, not a subtype of it.
9157 -- For integer types, right argument must be in Natural range
9172 -- Evaluate the exponentiation operator for dimensioned type
9175 else
9179 -- Set overflow checking bit. Much cleverer code needed here eventually
9180 -- and perhaps the Resolve routines should be separated for the various
9181 -- arithmetic operations, since they will need different processing. ???
9190 --------------------
9191 -- Resolve_Op_Not --
9192 --------------------
9198 -- This function determines if the parent node is a boolean operator or
9199 -- operation (comparison op, membership test, or short circuit form) and
9200 -- the not in question is the left operand of this operation. Note that
9201 -- if the not is in parens, then false is returned.
9203 -----------------------
9204 -- Parent_Is_Boolean --
9205 -----------------------
9208 begin
9212 else
9214 when N_Op_And |
9215 N_Op_Eq |
9216 N_Op_Ge |
9217 N_Op_Gt |
9218 N_Op_Le |
9219 N_Op_Lt |
9220 N_Op_Ne |
9221 N_Op_Or |
9222 N_Op_Xor |
9223 N_In |
9224 N_Not_In |
9225 N_And_Then |
9226 N_Or_Else =>
9236 -- Start of processing for Resolve_Op_Not
9238 begin
9239 -- Predefined operations on scalar types yield the base type. On the
9240 -- other hand, logical operations on arrays yield the type of the
9241 -- arguments (and the context).
9245 else
9249 -- Straightforward case of incorrect arguments
9256 -- Special case of probable missing parens
9260 Error_Msg_N
9263 else
9264 Error_Msg_N
9271 -- OK resolution of NOT
9273 else
9274 -- Warn if non-boolean types involved. This is a case like not a < b
9275 -- where a and b are modular, where we will get (not a) < b and most
9276 -- likely not (a < b) was intended.
9278 if Warn_On_Questionable_Missing_Parens
9280 and then Parent_Is_Boolean
9281 then
9285 -- Warn on double negation if checking redundant constructs
9287 if Warn_On_Redundant_Constructs
9292 then
9296 -- Complete resolution and evaluation of NOT
9306 -----------------------------
9307 -- Resolve_Operator_Symbol --
9308 -----------------------------
9310 -- Nothing to be done, all resolved already
9316 begin
9320 ----------------------------------
9321 -- Resolve_Qualified_Expression --
9322 ----------------------------------
9330 begin
9333 -- Protect call to Matching_Static_Array_Bounds to avoid costly
9334 -- operation if not needed.
9341 then
9342 Check_SPARK_05_Restriction
9346 -- A qualified expression requires an exact match of the type, class-
9347 -- wide matching is not allowed. However, if the qualifying type is
9348 -- specific and the expression has a class-wide type, it may still be
9349 -- okay, since it can be the result of the expansion of a call to a
9350 -- dispatching function, so we also have to check class-wideness of the
9351 -- type of the expression's original node.
9354 or else
9358 then
9362 -- If the target type is unconstrained, then we reset the type of the
9363 -- result from the type of the expression. For other cases, the actual
9364 -- subtype of the expression is the target type.
9368 then
9375 -- If we still have a qualified expression after the static evaluation,
9376 -- then apply a scalar range check if needed. The reason that we do this
9377 -- after the Eval call is that otherwise, the application of the range
9378 -- check may convert an illegal static expression and result in warning
9379 -- rather than giving an error (e.g Integer'(Integer'Last + 1)).
9386 ------------------------------
9387 -- Resolve_Raise_Expression --
9388 ------------------------------
9391 begin
9395 else
9400 -------------------
9401 -- Resolve_Range --
9402 -------------------
9409 -- Returns True if N is of the form X'First .. X'Last where X is the
9410 -- same entity for both attributes.
9412 --------------------
9413 -- First_Last_Ref --
9414 --------------------
9420 begin
9425 then
9426 declare
9429 begin
9433 then
9442 -- Start of processing for Resolve_Range
9444 begin
9449 -- Check for inappropriate range on unordered enumeration type
9453 -- Exclude X'First .. X'Last if X is the same entity for both
9455 and then not First_Last_Ref
9456 then
9458 Error_Msg_NE
9465 -- We have to check the bounds for being within the base range as
9466 -- required for a non-static context. Normally this is automatic and
9467 -- done as part of evaluating expressions, but the N_Range node is an
9468 -- exception, since in GNAT we consider this node to be a subexpression,
9469 -- even though in Ada it is not. The circuit in Sem_Eval could check for
9470 -- this, but that would put the test on the main evaluation path for
9471 -- expressions.
9476 -- Check for an ambiguous range over character literals. This will
9477 -- happen with a membership test involving only literals.
9485 -- If bounds are static, constant-fold them, so size computations are
9486 -- identical between front-end and back-end. Do not perform this
9487 -- transformation while analyzing generic units, as type information
9488 -- would be lost when reanalyzing the constant node in the instance.
9501 --------------------------
9502 -- Resolve_Real_Literal --
9503 --------------------------
9508 begin
9509 -- Special processing for fixed-point literals to make sure that the
9510 -- value is an exact multiple of small where this is required. We skip
9511 -- this for the universal real case, and also for generic types.
9517 then
9518 declare
9525 begin
9526 -- Case of literal is not an exact multiple of the Small
9530 -- For a source program literal for a decimal fixed-point type,
9531 -- this is statically illegal (RM 4.9(36)).
9536 then
9540 -- Generate a warning if literal from source
9543 and then Warn_On_Bad_Fixed_Value
9544 then
9545 Error_Msg_N
9547 N);
9550 -- Replace literal by a value that is the exact representation
9551 -- of a value of the type, i.e. a multiple of the small value,
9552 -- by truncation, since Machine_Rounds is false for all GNAT
9553 -- fixed-point types (RM 4.9(38)).
9563 -- In all cases, set the corresponding integer field
9569 -- Now replace the actual type by the expected type as usual
9575 -----------------------
9576 -- Resolve_Reference --
9577 -----------------------
9582 begin
9583 -- Replace general access with specific type
9591 -- If we are taking the reference of a volatile entity, then treat it as
9592 -- a potential modification of this entity. This is too conservative,
9593 -- but necessary because remove side effects can cause transformations
9594 -- of normal assignments into reference sequences that otherwise fail to
9595 -- notice the modification.
9602 --------------------------------
9603 -- Resolve_Selected_Component --
9604 --------------------------------
9619 -- Check whether this is the initialization of a component within an
9620 -- init proc (by assignment or call to another init proc). If true,
9621 -- there is no need for a discriminant check.
9623 --------------------
9624 -- Init_Component --
9625 --------------------
9628 begin
9629 return Inside_Init_Proc
9635 -- Start of processing for Resolve_Selected_Component
9637 begin
9640 -- Use the context type to select the prefix that has a selector
9641 -- of the correct name and type.
9649 else
9653 -- Locate selected component. For a private prefix the selector
9654 -- can denote a discriminant.
9658 -- The visible components of a class-wide type are those of
9659 -- the root type.
9669 then
9676 else
9680 Error_Msg_N
9685 else
9688 -- There may be an implicit dereference. Retrieve
9689 -- designated record type.
9693 else
9699 -- Resolution chooses the new interpretation.
9700 -- Find the component with the right name.
9705 loop
9722 -- There must be a legal interpretation at this point
9729 else
9730 -- Resolve prefix with its type
9735 -- Generate cross-reference. We needed to wait until full overloading
9736 -- resolution was complete to do this, since otherwise we can't tell if
9737 -- we are an lvalue or not.
9741 else
9745 -- If prefix is an access type, the node will be transformed into an
9746 -- explicit dereference during expansion. The type of the node is the
9747 -- designated type of that of the prefix.
9752 else
9756 -- Set flag for expander if discriminant check required
9763 and then not Init_Component
9764 then
9772 -- If the prefix is a record conversion, this may be a renamed
9773 -- discriminant whose bounds differ from those of the original
9774 -- one, so we must ensure that a range check is performed.
9779 then
9783 -- Note: No Eval processing is required, because the prefix is of a
9784 -- record type, or protected type, and neither can possibly be static.
9786 -- If the record type is atomic, and the component is non-atomic, then
9787 -- this is worth a warning, since we have a situation where the access
9788 -- to the component may cause extra read/writes of the atomic array
9789 -- object, or partial word accesses, both of which may be unexpected.
9795 then
9796 Error_Msg_N
9799 Error_Msg_N
9807 -------------------
9808 -- Resolve_Shift --
9809 -------------------
9816 begin
9817 -- We do the resolution using the base type, because intermediate values
9818 -- in expressions always are of the base type, not a subtype of it.
9831 ---------------------------
9832 -- Resolve_Short_Circuit --
9833 ---------------------------
9840 begin
9841 -- Ensure all actions associated with the left operand (e.g.
9842 -- finalization of transient controlled objects) are fully evaluated
9843 -- locally within an expression with actions. This is particularly
9844 -- helpful for coverage analysis. However this should not happen in
9845 -- generics.
9848 declare
9850 begin
9858 -- Set Comes_From_Source on L to preserve warnings for unset
9859 -- reference.
9868 -- Check for issuing warning for always False assert/check, this happens
9869 -- when assertions are turned off, in which case the pragma Assert/Check
9870 -- was transformed into:
9872 -- if False and then <condition> then ...
9874 -- and we detect this pattern
9876 if Warn_On_Assertion_Failure
9883 then
9884 declare
9887 begin
9888 -- Special handling of Asssert pragma
9892 then
9893 declare
9895 Original_Node
9896 (Expression
9899 begin
9900 -- Don't warn if original condition is explicit False,
9901 -- since obviously the failure is expected in this case.
9905 then
9908 -- Issue warning. We do not want the deletion of the
9909 -- IF/AND-THEN to take this message with it. We achieve this
9910 -- by making sure that the expanded code points to the Sloc
9911 -- of the expression, not the original pragma.
9913 else
9914 -- Note: Use Error_Msg_F here rather than Error_Msg_N.
9915 -- The source location of the expression is not usually
9916 -- the best choice here. For example, it gets located on
9917 -- the last AND keyword in a chain of boolean expressiond
9918 -- AND'ed together. It is best to put the message on the
9919 -- first character of the assertion, which is the effect
9920 -- of the First_Node call here.
9922 Error_Msg_F
9924 Expression
9929 -- Similar processing for Check pragma
9933 then
9934 -- Don't want to warn if original condition is explicit False
9936 declare
9938 Original_Node
9939 (Expression
9941 begin
9944 then
9947 -- Post warning
9949 else
9950 -- Again use Error_Msg_F rather than Error_Msg_N, see
9951 -- comment above for an explanation of why we do this.
9953 Error_Msg_F
9955 Expression
9963 -- Continue with processing of short circuit
9972 -------------------
9973 -- Resolve_Slice --
9974 -------------------
9983 begin
9986 -- Use the context type to select the prefix that yields the correct
9987 -- array type.
9989 declare
9996 begin
10004 then
10012 else
10017 else
10028 else
10038 -- If the prefix is an access to an unconstrained array, we must use
10039 -- the actual subtype of the object to perform the index checks. The
10040 -- object denoted by the prefix is implicit in the node, so we build
10041 -- an explicit representation for it in order to compute the actual
10042 -- subtype.
10047 declare
10051 begin
10062 then
10065 -- If the name is a selected component that depends on discriminants,
10066 -- build an actual subtype for it. This can happen only when the name
10067 -- itself is overloaded; otherwise the actual subtype is created when
10068 -- the selected component is analyzed.
10071 and then Full_Analysis
10073 then
10074 declare
10077 begin
10082 -- Maybe this should just be "else", instead of checking for the
10083 -- specific case of slice??? This is needed for the case where the
10084 -- prefix is an Image attribute, which gets expanded to a slice, and so
10085 -- has a constrained subtype which we want to use for the slice range
10086 -- check applied below (the range check won't get done if the
10087 -- unconstrained subtype of the 'Image is used).
10093 -- Obtain the type of the array index
10097 else
10101 -- If name was overloaded, set slice type correctly now
10105 -- Handle the generation of a range check that compares the array index
10106 -- against the discrete_range. The check is not applied to internally
10107 -- built nodes associated with the expansion of dispatch tables. Check
10108 -- that Ada.Tags has already been loaded to avoid extra dependencies on
10109 -- the unit.
10111 if Tagged_Type_Expansion
10117 then
10120 -- The discrete_range is specified by a subtype indication. Create a
10121 -- shallow copy and inherit the type, parent and source location from
10122 -- the discrete_range. This ensures that the range check is inserted
10123 -- relative to the slice and that the runtime exception points to the
10124 -- proper construct.
10133 -- The discrete_range is a regular range. Resolve the bounds and remove
10134 -- their side effects.
10136 else
10153 -- Check bad use of type with predicates
10155 declare
10158 begin
10161 then
10163 else
10168 Bad_Predicated_Subtype_Use
10173 -- Otherwise here is where we check suspicious indexes
10184 ----------------------------
10185 -- Resolve_String_Literal --
10186 ----------------------------
10197 begin
10198 -- For a string appearing in a concatenation, defer creation of the
10199 -- string_literal_subtype until the end of the resolution of the
10200 -- concatenation, because the literal may be constant-folded away. This
10201 -- is a useful optimization for long concatenation expressions.
10203 -- If the string is an aggregate built for a single character (which
10204 -- happens in a non-static context) or a is null string to which special
10205 -- checks may apply, we build the subtype. Wide strings must also get a
10206 -- string subtype if they come from a one character aggregate. Strings
10207 -- generated by attributes might be static, but it is often hard to
10208 -- determine whether the enclosing context is static, so we generate
10209 -- subtypes for them as well, thus losing some rarer optimizations ???
10210 -- Same for strings that come from a static conversion.
10212 Need_Check :=
10221 -- If the resolving type is itself a string literal subtype, we can just
10222 -- reuse it, since there is no point in creating another.
10228 and then not Need_Check
10230 N_Attribute_Reference,
10231 N_Qualified_Expression,
10232 N_Type_Conversion)
10233 then
10236 -- Do not generate a string literal subtype for the default expression
10237 -- of a formal parameter in GNATprove mode. This is because the string
10238 -- subtype is associated with the freezing actions of the subprogram,
10239 -- however freezing is disabled in GNATprove mode and as a result the
10240 -- subtype is unavailable.
10242 elsif GNATprove_Mode
10244 then
10247 -- Otherwise we must create a string literal subtype. Note that the
10248 -- whole idea of string literal subtypes is simply to avoid the need
10249 -- for building a full fledged array subtype for each literal.
10251 else
10257 or else Need_Check
10258 then
10265 then
10271 -- The validity of a null string has been checked in the call to
10272 -- Eval_String_Literal.
10277 -- Always accept string literal with component type Any_Character, which
10278 -- occurs in error situations and in comparisons of literals, both of
10279 -- which should accept all literals.
10284 -- If the type is bit-packed, then we always transform the string
10285 -- literal into a full fledged aggregate.
10290 -- Deal with cases of Wide_Wide_String, Wide_String, and String
10292 else
10293 -- For Standard.Wide_Wide_String, or any other type whose component
10294 -- type is Standard.Wide_Wide_Character, we know that all the
10295 -- characters in the string must be acceptable, since the parser
10296 -- accepted the characters as valid character literals.
10301 -- For the case of Standard.String, or any other type whose component
10302 -- type is Standard.Character, we must make sure that there are no
10303 -- wide characters in the string, i.e. that it is entirely composed
10304 -- of characters in range of type Character.
10306 -- If the string literal is the result of a static concatenation, the
10307 -- test has already been performed on the components, and need not be
10308 -- repeated.
10312 then
10316 -- If we are out of range, post error. This is one of the
10317 -- very few places that we place the flag in the middle of
10318 -- a token, right under the offending wide character. Not
10319 -- quite clear if this is right wrt wide character encoding
10320 -- sequences, but it's only an error message.
10322 Error_Msg
10329 -- For the case of Standard.Wide_String, or any other type whose
10330 -- component type is Standard.Wide_Character, we must make sure that
10331 -- there are no wide characters in the string, i.e. that it is
10332 -- entirely composed of characters in range of type Wide_Character.
10334 -- If the string literal is the result of a static concatenation,
10335 -- the test has already been performed on the components, and need
10336 -- not be repeated.
10340 then
10344 -- If we are out of range, post error. This is one of the
10345 -- very few places that we place the flag in the middle of
10346 -- a token, right under the offending wide character.
10348 -- This is not quite right, because characters in general
10349 -- will take more than one character position ???
10351 Error_Msg
10358 -- If the root type is not a standard character, then we will convert
10359 -- the string into an aggregate and will let the aggregate code do
10360 -- the checking. Standard Wide_Wide_Character is also OK here.
10362 else
10366 -- See if the component type of the array corresponding to the string
10367 -- has compile time known bounds. If yes we can directly check
10368 -- whether the evaluation of the string will raise constraint error.
10369 -- Otherwise we need to transform the string literal into the
10370 -- corresponding character aggregate and let the aggregate code do
10371 -- the checking.
10375 -- Check for the case of full range, where we are definitely OK
10381 -- Here the range is not the complete base type range, so check
10383 declare
10391 begin
10394 then
10400 then
10401 Apply_Compile_Time_Constraint_Error
10403 CE_Range_Check_Failed,
10414 -- If we got here we meed to transform the string literal into the
10415 -- equivalent qualified positional array aggregate. This is rather
10416 -- heavy artillery for this situation, but it is hard work to avoid.
10418 declare
10423 begin
10424 -- Build the character literals, we give them source locations that
10425 -- correspond to the string positions, which is a bit tricky given
10426 -- the possible presence of wide character escape sequences.
10440 -- Should we have a call to Skip_Wide here ???
10442 -- ??? else
10443 -- Skip_Wide (P);
10451 Expression =>
10458 -----------------------------
10459 -- Resolve_Type_Conversion --
10460 -----------------------------
10472 -- Set to False to suppress cases where we want to suppress the test
10473 -- for redundancy to avoid possible false positives on this warning.
10475 begin
10476 if not Conv_OK
10478 then
10482 -- If the Operand Etype is Universal_Fixed, then the conversion is
10483 -- never redundant. We need this check because by the time we have
10484 -- finished the rather complex transformation, the conversion looks
10485 -- redundant when it is not.
10490 -- If the operand is marked as Any_Fixed, then special processing is
10491 -- required. This is also a case where we suppress the test for a
10492 -- redundant conversion, since most certainly it is not redundant.
10497 -- Mixed-mode operation involving a literal. Context must be a fixed
10498 -- type which is applied to the literal subsequently.
10506 or else
10508 then
10509 -- Return if expression is ambiguous
10514 -- If nothing else, the available fixed type is Duration
10516 else
10520 -- Resolve the real operand with largest available precision
10524 else
10530 -- If the operand is a literal (it could be a non-static and
10531 -- illegal exponentiation) check whether the use of Duration
10532 -- is potentially inaccurate.
10537 then
10538 Error_Msg_N
10541 Error_Msg_N
10548 then
10551 else
10560 -- In SPARK, a type conversion between array types should be restricted
10561 -- to types which have matching static bounds.
10563 -- Protect call to Matching_Static_Array_Bounds to avoid costly
10564 -- operation if not needed.
10571 then
10572 Check_SPARK_05_Restriction
10576 -- In formal mode, the operand of an ancestor type conversion must be an
10577 -- object (not an expression).
10585 then
10591 -- Note: we do the Eval_Type_Conversion call before applying the
10592 -- required checks for a subtype conversion. This is important, since
10593 -- both are prepared under certain circumstances to change the type
10594 -- conversion to a constraint error node, but in the case of
10595 -- Eval_Type_Conversion this may reflect an illegality in the static
10596 -- case, and we would miss the illegality (getting only a warning
10597 -- message), if we applied the type conversion checks first.
10601 -- Even when evaluation is not possible, we may be able to simplify the
10602 -- conversion or its expression. This needs to be done before applying
10603 -- checks, since otherwise the checks may use the original expression
10604 -- and defeat the simplifications. This is specifically the case for
10605 -- elimination of the floating-point Truncation attribute in
10606 -- float-to-int conversions.
10610 -- If after evaluation we still have a type conversion, then we may need
10611 -- to apply checks required for a subtype conversion.
10613 -- Skip these type conversion checks if universal fixed operands
10614 -- operands involved, since range checks are handled separately for
10615 -- these cases (in the appropriate Expand routines in unit Exp_Fixd).
10621 then
10625 -- Issue warning for conversion of simple object to its own type. We
10626 -- have to test the original nodes, since they may have been rewritten
10627 -- by various optimizations.
10631 -- Here we test for a redundant conversion if the warning mode is
10632 -- active (and was not locally reset), and we have a type conversion
10633 -- from source not appearing in a generic instance.
10635 if Test_Redundant
10638 and then not In_Instance
10639 then
10643 -- If the node is part of a larger expression, the Target_Type
10644 -- may not be the original type of the node if the context is a
10645 -- condition. Recover original type to see if conversion is needed.
10649 then
10653 -- If we have an entity name, then give the warning if the entity
10654 -- is the right type, or if it is a loop parameter covered by the
10655 -- original type (that's needed because loop parameters have an
10656 -- odd subtype coming from the bounds).
10659 and then
10661 or else
10665 -- If not an entity, then type of expression must match
10668 then
10669 -- One more check, do not give warning if the analyzed conversion
10670 -- has an expression with non-static bounds, and the bounds of the
10671 -- target are static. This avoids junk warnings in cases where the
10672 -- conversion is necessary to establish staticness, for example in
10673 -- a case statement.
10677 then
10680 -- Finally, if this type conversion occurs in a context requiring
10681 -- a prefix, and the expression is a qualified expression then the
10682 -- type conversion is not redundant, since a qualified expression
10683 -- is not a prefix, whereas a type conversion is. For example, "X
10684 -- := T'(Funx(...)).Y;" is illegal because a selected component
10685 -- requires a prefix, but a type conversion makes it legal: "X :=
10686 -- T(T'(Funx(...))).Y;"
10688 -- In Ada 2012, a qualified expression is a name, so this idiom is
10689 -- no longer needed, but we still suppress the warning because it
10690 -- seems unfriendly for warnings to pop up when you switch to the
10691 -- newer language version.
10695 N_Indexed_Component,
10696 N_Selected_Component,
10697 N_Slice,
10698 N_Explicit_Dereference)
10699 then
10702 -- Never warn on conversion to Long_Long_Integer'Base since
10703 -- that is most likely an artifact of the extended overflow
10704 -- checking and comes from complex expanded code.
10709 -- Here we give the redundant conversion warning. If it is an
10710 -- entity, give the name of the entity in the message. If not,
10711 -- just mention the expression.
10713 -- Shoudn't we test Warn_On_Redundant_Constructs here ???
10715 else
10718 Error_Msg_NE -- CODEFIX
10721 else
10722 Error_Msg_NE
10730 -- Ada 2005 (AI-251): Handle class-wide interface type conversions.
10731 -- No need to perform any interface conversion if the type of the
10732 -- expression coincides with the target type.
10735 and then Expander_Active
10737 then
10738 declare
10742 begin
10743 -- If the type of the operand is a limited view, use nonlimited
10744 -- view when available. If it is a class-wide type, recover the
10745 -- class-wide type of the nonlimited view.
10750 then
10756 then
10773 -- Conversion from interface type
10777 -- Ada 2005 (AI-217): Handle entities from limited views
10781 Error_Msg_NE -- CODEFIX
10784 Error_Msg_N
10786 N);
10789 and then not
10792 then
10794 Error_Msg_NE -- CODEFIX
10797 Error_Msg_N
10799 N);
10801 else
10805 -- Conversion to interface type
10809 -- Handle subtypes
10816 or else Interface_Present_In_Ancestor
10819 then
10821 else
10824 Error_Msg_N
10832 -- Ada 2012: if target type has predicates, the result requires a
10833 -- predicate check. If the context is a call to another predicate
10834 -- check we must prevent infinite recursion.
10840 or else
10842 then
10845 else
10850 -- If at this stage we have a real to integer conversion, make sure
10851 -- that the Do_Range_Check flag is set, because such conversions in
10852 -- general need a range check. We only need this if expansion is off
10853 -- or we are in GNATProve mode.
10859 then
10864 ----------------------
10865 -- Resolve_Unary_Op --
10866 ----------------------
10875 begin
10878 Check_SPARK_05_Restriction
10882 -- Deal with intrinsic unary operators
10888 then
10893 -- Deal with universal cases
10896 or else
10898 then
10905 -- Generate warning for expressions like abs (x mod 2)
10907 if Warn_On_Redundant_Constructs
10909 then
10913 Error_Msg_N -- CODEFIX
10918 -- Deal with reference generation
10925 -- Set overflow checking bit. Much cleverer code needed here eventually
10926 -- and perhaps the Resolve routines should be separated for the various
10927 -- arithmetic operations, since they will need different processing ???
10935 -- Generate warning for expressions like -5 mod 3 for integers. No need
10936 -- to worry in the floating-point case, since parens do not affect the
10937 -- result so there is no point in giving in a warning.
10939 declare
10948 begin
10949 if Warn_On_Questionable_Missing_Parens
10953 then
10956 -- We are looking for cases where the right operand is not
10957 -- parenthesized, and is a binary operator, multiply, divide, or
10958 -- mod. These are the cases where the grouping can affect results.
10962 then
10963 -- For mod, we always give the warning, since the value is
10964 -- affected by the parenthesization (e.g. (-5) mod 315 /=
10965 -- -(5 mod 315)). But for the other cases, the only concern is
10966 -- overflow, e.g. for the case of 8 big signed (-(2 * 64)
10967 -- overflows, but (-2) * 64 does not). So we try to give the
10968 -- message only when overflow is possible.
10972 then
10977 else
10983 else
10987 -- Note that the test below is deliberately excluding the
10988 -- largest negative number, since that is a potentially
10989 -- troublesome case (e.g. -2 * x, where the result is the
10990 -- largest negative integer has an overflow with 2 * x).
10997 -- For the multiplication case, the only case we have to worry
10998 -- about is when (-a)*b is exactly the largest negative number
10999 -- so that -(a*b) can cause overflow. This can only happen if
11000 -- a is a power of 2, and more generally if any operand is a
11001 -- constant that is not a power of 2, then the parentheses
11002 -- cannot affect whether overflow occurs. We only bother to
11003 -- test the left most operand
11005 -- Loop looking at left operands for one that has known value
11012 -- Operand value of 0 or 1 skips warning
11017 -- Otherwise check power of 2, if power of 2, warn, if
11018 -- anything else, skip warning.
11020 else
11024 else
11033 -- Keep looking at left operands
11038 -- For rem or "/" we can only have a problematic situation
11039 -- if the divisor has a value of minus one or one. Otherwise
11040 -- overflow is impossible (divisor > 1) or we have a case of
11041 -- division by zero in any case.
11046 then
11050 -- If we fall through warning should be issued
11052 -- Shouldn't we test Warn_On_Questionable_Missing_Parens ???
11054 Error_Msg_N
11061 ----------------------------------
11062 -- Resolve_Unchecked_Expression --
11063 ----------------------------------
11065 procedure Resolve_Unchecked_Expression
11068 is
11069 begin
11074 ---------------------------------------
11075 -- Resolve_Unchecked_Type_Conversion --
11076 ---------------------------------------
11078 procedure Resolve_Unchecked_Type_Conversion
11081 is
11087 begin
11088 -- Resolve operand using its own type
11092 -- In an inlined context, the unchecked conversion may be applied
11093 -- to a literal, in which case its type is the type of the context.
11094 -- (In other contexts conversions cannot apply to literals).
11096 if In_Inlined_Body
11100 then
11108 ------------------------------
11109 -- Rewrite_Operator_As_Call --
11110 ------------------------------
11117 begin
11124 New_N :=
11135 ------------------------------
11136 -- Rewrite_Renamed_Operator --
11137 ------------------------------
11139 procedure Rewrite_Renamed_Operator
11143 is
11148 begin
11149 -- Do not perform this transformation within a pre/postcondition,
11150 -- because the expression will be re-analyzed, and the transformation
11151 -- might affect the visibility of the operator, e.g. in an instance.
11157 -- Rewrite the operator node using the real operator, not its renaming.
11158 -- Exclude user-defined intrinsic operations of the same name, which are
11159 -- treated separately and rewritten as calls.
11168 -- Indicate that both the original entity and its renaming are
11169 -- referenced at this point.
11180 -- If the context type is private, add the appropriate conversions so
11181 -- that the operator is applied to the full view. This is done in the
11182 -- routines that resolve intrinsic operators.
11186 then
11188 when N_Op_Add | N_Op_Subtract | N_Op_Multiply | N_Op_Divide |
11189 N_Op_Expon | N_Op_Mod | N_Op_Rem =>
11202 -- Operator renames a user-defined operator of the same name. Use the
11203 -- original operator in the node, which is the one Gigi knows about.
11210 -----------------------
11211 -- Set_Slice_Subtype --
11212 -----------------------
11214 -- Build an implicit subtype declaration to represent the type delivered by
11215 -- the slice. This is an abbreviated version of an array subtype. We define
11216 -- an index subtype for the slice, using either the subtype name or the
11217 -- discrete range of the slice. To be consistent with index usage elsewhere
11218 -- we create a list header to hold the single index. This list is not
11219 -- otherwise attached to the syntax tree.
11230 begin
11236 else
11237 -- We force the evaluation of a range. This is definitely needed in
11238 -- the renamed case, and seems safer to do unconditionally. Note in
11239 -- any case that since we will create and insert an Itype referring
11240 -- to this range, we must make sure any side effect removal actions
11241 -- are inserted before the Itype definition.
11247 -- If the discrete range is given by a subtype indication, the
11248 -- type of the slice is the base of the subtype mark.
11251 declare
11253 begin
11262 -- Take a new copy of Drange (where bounds have been rewritten to
11263 -- reference side-effect-free names). Using a separate tree ensures
11264 -- that further expansion (e.g. while rewriting a slice assignment
11265 -- into a FOR loop) does not attempt to remove side effects on the
11266 -- bounds again (which would cause the bounds in the index subtype
11267 -- definition to refer to temporaries before they are defined) (the
11268 -- reason is that some names are considered side effect free here
11269 -- for the subtype, but not in the context of a loop iteration
11270 -- scheme).
11291 -- The Etype of the existing Slice node is reset to this slice subtype.
11292 -- Its bounds are obtained from its first index.
11296 -- For packed slice subtypes, freeze immediately (except in the case of
11297 -- being in a "spec expression" where we never freeze when we first see
11298 -- the expression).
11303 -- For all other cases insert an itype reference in the slice's actions
11304 -- so that the itype is frozen at the proper place in the tree (i.e. at
11305 -- the point where actions for the slice are analyzed). Note that this
11306 -- is different from freezing the itype immediately, which might be
11307 -- premature (e.g. if the slice is within a transient scope). This needs
11308 -- to be done only if expansion is enabled.
11315 --------------------------------
11316 -- Set_String_Literal_Subtype --
11317 --------------------------------
11325 begin
11337 -- The low bound is set from the low bound of the corresponding index
11338 -- type. Note that we do not store the high bound in the string literal
11339 -- subtype, but it can be deduced if necessary from the length and the
11340 -- low bound.
11345 -- If the lower bound is not static we create a range for the string
11346 -- literal, using the index type and the known length of the literal.
11347 -- The index type is not necessarily Positive, so the upper bound is
11348 -- computed as T'Val (T'Pos (Low_Bound) + L - 1).
11350 else
11351 declare
11357 Prefix =>
11361 Left_Opnd =>
11364 Prefix =>
11366 Expressions =>
11368 Right_Opnd =>
11377 begin
11379 Set_String_Literal_Low_Bound
11382 else
11383 -- If the index type is an enumeration type, build bounds
11384 -- expression with attributes.
11386 Set_String_Literal_Low_Bound
11390 Prefix =>
11397 -- Build bona fide subtype for the string, and wrap it in an
11398 -- unchecked conversion, because the backend expects the
11399 -- String_Literal_Subtype to have a static lower bound.
11401 Index_Subtype :=
11408 -- In the context, the Index_Type may already have a constraint,
11409 -- so use common base type on string subtype. The base type may
11410 -- be used when generating attributes of the string, for example
11411 -- in the context of a slice assignment.
11436 ------------------------------
11437 -- Simplify_Type_Conversion --
11438 ------------------------------
11441 begin
11443 declare
11448 begin
11449 -- Special processing if the conversion is the expression of a
11450 -- Rounding or Truncation attribute reference. In this case we
11451 -- replace:
11453 -- ityp (ftyp'Rounding (x)) or ityp (ftyp'Truncation (x))
11455 -- by
11457 -- ityp (x)
11459 -- with the Float_Truncate flag set to False or True respectively,
11460 -- which is more efficient.
11463 and then
11469 Name_Truncation)
11470 then
11471 declare
11474 begin
11484 -----------------------------
11485 -- Unique_Fixed_Point_Type --
11486 -----------------------------
11495 -- Give error messages for true ambiguity. Messages are posted on node
11496 -- N, and entities T1, T2 are the possible interpretations.
11498 -----------------------
11499 -- Fixed_Point_Error --
11500 -----------------------
11503 begin
11509 -- Start of processing for Unique_Fixed_Point_Type
11511 begin
11512 -- The operations on Duration are visible, so Duration is always a
11513 -- possible interpretation.
11517 -- Look for fixed-point types in enclosing scopes
11526 then
11528 Fixed_Point_Error;
11530 else
11541 -- Look for visible fixed type declarations in the context
11552 then
11554 Fixed_Point_Error;
11556 else
11569 Error_Msg_NE
11571 else
11572 Error_Msg_NE
11579 ----------------------
11580 -- Valid_Conversion --
11581 ----------------------
11583 function Valid_Conversion
11588 is
11593 function Conversion_Check
11596 -- Little routine to post Msg if Valid is False, returns Valid value
11599 -- If Report_Errs, then calls Errout.Error_Msg_N with its arguments
11601 procedure Conversion_Error_NE
11605 -- If Report_Errs, then calls Errout.Error_Msg_NE with its arguments
11607 function Valid_Tagged_Conversion
11610 -- Specifically test for validity of tagged conversions
11613 -- Check index and component conformance, and accessibility levels if
11614 -- the component types are anonymous access types (Ada 2005).
11616 ----------------------
11617 -- Conversion_Check --
11618 ----------------------
11620 function Conversion_Check
11623 is
11624 begin
11625 if not Valid
11627 -- A generic unit has already been analyzed and we have verified
11628 -- that a particular conversion is OK in that context. Since the
11629 -- instance is reanalyzed without relying on the relationships
11630 -- established during the analysis of the generic, it is possible
11631 -- to end up with inconsistent views of private types. Do not emit
11632 -- the error message in such cases. The rest of the machinery in
11633 -- Valid_Conversion still ensures the proper compatibility of
11634 -- target and operand types.
11636 and then not In_Instance
11637 then
11644 ------------------------
11645 -- Conversion_Error_N --
11646 ------------------------
11649 begin
11655 -------------------------
11656 -- Conversion_Error_NE --
11657 -------------------------
11659 procedure Conversion_Error_NE
11663 is
11664 begin
11670 ----------------------------
11671 -- Valid_Array_Conversion --
11672 ----------------------------
11675 is
11690 begin
11691 -- Error if wrong number of dimensions
11693 if
11695 then
11696 Conversion_Error_N
11700 -- Number of dimensions matches
11702 else
11703 -- Loop through indexes of the two arrays
11711 -- Error if index types are incompatible
11717 then
11718 Conversion_Error_N
11720 Operand);
11728 -- If component types have same base type, all set
11733 -- Here if base types of components are not the same. The only
11734 -- time this is allowed is if we have anonymous access types.
11736 -- The conversion of arrays of anonymous access types can lead
11737 -- to dangling pointers. AI-392 formalizes the accessibility
11738 -- checks that must be applied to such conversions to prevent
11739 -- out-of-scope references.
11741 elsif Ekind_In
11743 E_Anonymous_Access_Subprogram_Type)
11745 and then
11747 then
11750 then
11753 Conversion_Error_N
11763 -- Conversion not allowed because of accessibility levels
11765 else
11766 Conversion_Error_N
11772 else
11776 -- All other cases where component base types do not match
11778 else
11779 Conversion_Error_N
11781 Operand);
11785 -- Check that component subtypes statically match. For numeric
11786 -- types this means that both must be either constrained or
11787 -- unconstrained. For enumeration types the bounds must match.
11788 -- All of this is checked in Subtypes_Statically_Match.
11790 if not Subtypes_Statically_Match
11792 then
11793 Conversion_Error_N
11802 -----------------------------
11803 -- Valid_Tagged_Conversion --
11804 -----------------------------
11806 function Valid_Tagged_Conversion
11809 is
11810 begin
11811 -- Upward conversions are allowed (RM 4.6(22))
11815 then
11818 -- Downward conversion are allowed if the operand is class-wide
11819 -- (RM 4.6(23)).
11823 then
11828 then
11829 return
11833 -- Ada 2005 (AI-251): The conversion to/from interface types is
11834 -- always valid
11839 -- If the operand is a class-wide type obtained through a limited_
11840 -- with clause, and the context includes the nonlimited view, use
11841 -- it to determine whether the conversion is legal.
11847 then
11852 then
11855 else
11856 Conversion_Error_NE
11863 -- Start of processing for Valid_Conversion
11865 begin
11869 declare
11877 begin
11878 -- Remove procedure calls, which syntactically cannot appear in
11879 -- this context, but which cannot be removed by type checking,
11880 -- because the context does not impose a type.
11882 -- The node may be labelled overloaded, but still contain only one
11883 -- interpretation because others were discarded earlier. If this
11884 -- is the case, retain the single interpretation if legal.
11892 then
11893 -- More than one candidate interpretation is available
11901 -- When compiling for a system where Address is of a visible
11902 -- integer type, spurious ambiguities can be produced when
11903 -- arithmetic operations have a literal operand and return
11904 -- System.Address or a descendant of it. These ambiguities
11905 -- are usually resolved by the context, but for conversions
11906 -- there is no context type and the removal of the spurious
11907 -- operations must be done explicitly here.
11909 if not Address_Is_Private
11911 then
11936 Conversion_Error_N
11939 -- If the interpretation involves a standard operator, use
11940 -- the location of the type, which may be user-defined.
11944 else
11948 Conversion_Error_N -- CODEFIX
11953 else
11957 Conversion_Error_N -- CODEFIX
11969 -- Deal with conversion of integer type to address if the pragma
11970 -- Allow_Integer_Address is in effect. We convert the conversion to
11971 -- an unchecked conversion in this case and we are all done.
11979 -- If we are within a child unit, check whether the type of the
11980 -- expression has an ancestor in a parent unit, in which case it
11981 -- belongs to its derivation class even if the ancestor is private.
11982 -- See RM 7.3.1 (5.2/3).
11986 -- Numeric types
11990 -- A universal fixed expression can be converted to any numeric type
11995 -- Also no need to check when in an instance or inlined body, because
11996 -- the legality has been established when the template was analyzed.
11997 -- Furthermore, numeric conversions may occur where only a private
11998 -- view of the operand type is visible at the instantiation point.
11999 -- This results in a spurious error if we check that the operand type
12000 -- is a numeric type.
12002 -- Note: in a previous version of this unit, the following tests were
12003 -- applied only for generated code (Comes_From_Source set to False),
12004 -- but in fact the test is required for source code as well, since
12005 -- this situation can arise in source code.
12010 -- Otherwise we need the conversion check
12012 else
12013 return Conversion_Check
12015 or else
12021 -- Array types
12027 then
12028 Conversion_Error_N
12032 else
12036 -- Ada 2005 (AI-251): Internally generated conversions of access to
12037 -- interface types added to force the displacement of the pointer to
12038 -- reference the corresponding dispatch table.
12043 then
12046 -- Ada 2005 (AI-251): Anonymous access types where target references an
12047 -- interface type.
12051 E_Anonymous_Access_Type)
12053 then
12054 -- Check the static accessibility rule of 4.6(17). Note that the
12055 -- check is not enforced when within an instance body, since the
12056 -- RM requires such cases to be caught at run time.
12058 -- If the operand is a rewriting of an allocator no check is needed
12059 -- because there are no accessibility issues.
12067 then
12068 -- In an instance, this is a run-time check, but one we know
12069 -- will fail, so generate an appropriate warning. The raise
12070 -- will be generated by Expand_N_Type_Conversion.
12074 Conversion_Error_N
12076 Operand);
12079 else
12080 Conversion_Error_N
12082 Operand);
12086 -- Special accessibility checks are needed in the case of access
12087 -- discriminants declared for a limited type.
12091 then
12092 -- When the operand is a selected access discriminant the check
12093 -- needs to be made against the level of the object denoted by
12094 -- the prefix of the selected name (Object_Access_Level handles
12095 -- checking the prefix of the operand for this case).
12100 then
12101 -- In an instance, this is a run-time check, but one we know
12102 -- will fail, so generate an appropriate warning. The raise
12103 -- will be generated by Expand_N_Type_Conversion.
12107 Conversion_Error_N
12112 -- Real error if not in instance body
12114 else
12115 Conversion_Error_N
12122 -- The case of a reference to an access discriminant from
12123 -- within a limited type declaration (which will appear as
12124 -- a discriminal) is always illegal because the level of the
12125 -- discriminant is considered to be deeper than any (nameable)
12126 -- access type.
12130 and then
12133 then
12134 Conversion_Error_N
12136 Operand);
12144 -- General and anonymous access types
12147 E_Anonymous_Access_Type)
12148 and then
12149 Conversion_Check
12151 and then not
12153 E_Access_Protected_Subprogram_Type),
12155 then
12158 then
12159 Conversion_Error_N
12164 -- Check the static accessibility rule of 4.6(17). Note that the
12165 -- check is not enforced when within an instance body, since the RM
12166 -- requires such cases to be caught at run time.
12171 N_Object_Declaration
12172 then
12173 -- Ada 2012 (AI05-0149): Perform legality checking on implicit
12174 -- conversions from an anonymous access type to a named general
12175 -- access type. Such conversions are not allowed in the case of
12176 -- access parameters and stand-alone objects of an anonymous
12177 -- access type. The implicit conversion case is recognized by
12178 -- testing that Comes_From_Source is False and that it's been
12179 -- rewritten. The Comes_From_Source test isn't sufficient because
12180 -- nodes in inlined calls to predefined library routines can have
12181 -- Comes_From_Source set to False. (Is there a better way to test
12182 -- for implicit conversions???)
12189 then
12192 -- Implicit conversions aren't allowed for objects of an
12193 -- anonymous access type, since such objects have nonstatic
12194 -- levels in Ada 2012.
12197 N_Object_Declaration
12198 then
12199 Conversion_Error_N
12204 -- Implicit conversions aren't allowed for anonymous access
12205 -- parameters. The "not Is_Local_Anonymous_Access_Type" test
12206 -- is done to exclude anonymous access results.
12210 N_Function_Specification,
12211 N_Procedure_Specification)
12212 then
12213 Conversion_Error_N
12218 -- This is a case where there's an enclosing object whose
12219 -- to which the "statically deeper than" relationship does
12220 -- not apply (such as an access discriminant selected from
12221 -- a dereference of an access parameter).
12225 then
12226 Conversion_Error_N
12231 -- In other cases, the level of the operand's type must be
12232 -- statically less deep than that of the target type, else
12233 -- implicit conversion is disallowed (by RM12-8.6(27.1/3)).
12237 then
12238 Conversion_Error_N
12247 then
12248 -- In an instance, this is a run-time check, but one we know
12249 -- will fail, so generate an appropriate warning. The raise
12250 -- will be generated by Expand_N_Type_Conversion.
12254 Conversion_Error_N
12256 Operand);
12259 -- If not in an instance body, this is a real error
12261 else
12262 -- Avoid generation of spurious error message
12265 Conversion_Error_N
12267 Operand);
12273 -- Special accessibility checks are needed in the case of access
12274 -- discriminants declared for a limited type.
12278 then
12279 -- When the operand is a selected access discriminant the check
12280 -- needs to be made against the level of the object denoted by
12281 -- the prefix of the selected name (Object_Access_Level handles
12282 -- checking the prefix of the operand for this case).
12287 then
12288 -- In an instance, this is a run-time check, but one we know
12289 -- will fail, so generate an appropriate warning. The raise
12290 -- will be generated by Expand_N_Type_Conversion.
12294 Conversion_Error_N
12299 -- If not in an instance body, this is a real error
12301 else
12302 Conversion_Error_N
12309 -- The case of a reference to an access discriminant from
12310 -- within a limited type declaration (which will appear as
12311 -- a discriminal) is always illegal because the level of the
12312 -- discriminant is considered to be deeper than any (nameable)
12313 -- access type.
12316 and then
12319 then
12320 Conversion_Error_N
12322 Operand);
12328 -- In the presence of limited_with clauses we have to use nonlimited
12329 -- views, if available.
12333 -- Helper function to handle limited views
12335 --------------------------
12336 -- Full_Designated_Type --
12337 --------------------------
12342 begin
12343 -- Handle the limited view of a type
12348 then
12350 else
12355 -- Local Declarations
12363 -- Start of processing for Check_Limited
12365 begin
12369 else
12371 Conversion_Error_NE
12376 -- Ada 2005 AI-384: legality rule is symmetric in both
12377 -- designated types. The conversion is legal (with possible
12378 -- constraint check) if either designated type is
12379 -- unconstrained.
12382 or else
12384 and then
12387 then
12388 -- Special case, if Value_Size has been used to make the
12389 -- sizes different, the conversion is not allowed even
12390 -- though the subtypes statically match.
12395 then
12396 Conversion_Error_NE
12399 Conversion_Error_NE
12404 -- Normal case where conversion is allowed
12406 else
12410 else
12411 Error_Msg_NE
12419 -- Access to subprogram types. If the operand is an access parameter,
12420 -- the type has a deeper accessibility that any master, and cannot be
12421 -- assigned. We must make an exception if the conversion is part of an
12422 -- assignment and the target is the return object of an extended return
12423 -- statement, because in that case the accessibility check takes place
12424 -- after the return.
12428 -- Note: this test of Opnd_Type is there to prevent entering this
12429 -- branch in the case of a remote access to subprogram type, which
12430 -- is internally represented as an E_Record_Type.
12433 then
12437 and then
12441 then
12442 Conversion_Error_N
12444 Operand);
12445 Conversion_Error_N
12448 Operand);
12450 Error_Msg_NE
12455 -- Check that the designated types are subtype conformant
12461 -- Check the static accessibility rule of 4.6(20)
12465 then
12466 Conversion_Error_N
12468 Operand);
12470 -- Check that if the operand type is declared in a generic body,
12471 -- then the target type must be declared within that same body
12472 -- (enforces last sentence of 4.6(20)).
12475 declare
12481 begin
12488 Conversion_Error_N
12497 -- Remote access to subprogram types
12501 then
12502 -- It is valid to convert from one RAS type to another provided
12503 -- that their specification statically match.
12505 -- Note: at this point, remote access to subprogram types have been
12506 -- expanded to their E_Record_Type representation, and we need to
12507 -- go back to the original access type definition using the
12508 -- Corresponding_Remote_Type attribute in order to check that the
12509 -- designated profiles match.
12514 Check_Subtype_Conformant
12517 Old_Id =>
12519 Err_Loc =>
12520 N);
12523 -- If it was legal in the generic, it's legal in the instance
12528 -- If both are tagged types, check legality of view conversions
12531 and then
12533 then
12536 -- Types derived from the same root type are convertible
12541 -- In an instance or an inlined body, there may be inconsistent views of
12542 -- the same type, or of types derived from a common root.
12545 and then
12548 then
12551 -- Special check for common access type error case
12555 then
12557 Conversion_Error_NE -- CODEFIX
12561 -- Here we have a real conversion error
12563 else
12564 Conversion_Error_NE