1 /* Language-level data type conversion for GNU C++.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
4 Hacked by Michael Tiemann (tiemann@cygnus.com)
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GCC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to
20 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
21 Boston, MA 02110-1301, USA. */
24 /* This file contains the functions for converting C++ expressions
25 to different data types. The only entry point is `convert'.
26 Every language front end must have a `convert' function
27 but what kind of conversions it does will depend on the language. */
31 #include "coretypes.h"
41 static tree
cp_convert_to_pointer (tree
, tree
, bool);
42 static tree
convert_to_pointer_force (tree
, tree
);
43 static tree
build_type_conversion (tree
, tree
);
44 static tree
build_up_reference (tree
, tree
, int, tree
);
45 static void warn_ref_binding (tree
, tree
, tree
);
47 /* Change of width--truncation and extension of integers or reals--
48 is represented with NOP_EXPR. Proper functioning of many things
49 assumes that no other conversions can be NOP_EXPRs.
51 Conversion between integer and pointer is represented with CONVERT_EXPR.
52 Converting integer to real uses FLOAT_EXPR
53 and real to integer uses FIX_TRUNC_EXPR.
55 Here is a list of all the functions that assume that widening and
56 narrowing is always done with a NOP_EXPR:
57 In convert.c, convert_to_integer.
58 In c-typeck.c, build_binary_op_nodefault (boolean ops),
59 and c_common_truthvalue_conversion.
60 In expr.c: expand_expr, for operands of a MULT_EXPR.
61 In fold-const.c: fold.
62 In tree.c: get_narrower and get_unwidened.
64 C++: in multiple-inheritance, converting between pointers may involve
65 adjusting them by a delta stored within the class definition. */
67 /* Subroutines of `convert'. */
69 /* if converting pointer to pointer
70 if dealing with classes, check for derived->base or vice versa
71 else if dealing with method pointers, delegate
73 else if converting class, pass off to build_type_conversion
74 else try C-style pointer conversion. If FORCE is true then allow
75 conversions via virtual bases (these are permitted by reinterpret_cast,
76 but not static_cast). */
79 cp_convert_to_pointer (tree type
, tree expr
, bool force
)
81 tree intype
= TREE_TYPE (expr
);
84 if (intype
== error_mark_node
)
85 return error_mark_node
;
87 if (IS_AGGR_TYPE (intype
))
89 intype
= complete_type (intype
);
90 if (!COMPLETE_TYPE_P (intype
))
92 error ("can't convert from incomplete type %qT to %qT",
94 return error_mark_node
;
97 rval
= build_type_conversion (type
, expr
);
100 if (rval
== error_mark_node
)
101 error ("conversion of %qE from %qT to %qT is ambiguous",
107 /* Handle anachronistic conversions from (::*)() to cv void* or (*)(). */
108 if (TREE_CODE (type
) == POINTER_TYPE
109 && (TREE_CODE (TREE_TYPE (type
)) == FUNCTION_TYPE
110 || VOID_TYPE_P (TREE_TYPE (type
))))
112 if (TYPE_PTRMEMFUNC_P (intype
)
113 || TREE_CODE (intype
) == METHOD_TYPE
)
114 return convert_member_func_to_ptr (type
, expr
);
115 if (TREE_CODE (TREE_TYPE (expr
)) == POINTER_TYPE
)
116 return build_nop (type
, expr
);
117 intype
= TREE_TYPE (expr
);
120 if (expr
== error_mark_node
)
121 return error_mark_node
;
123 form
= TREE_CODE (intype
);
125 if (POINTER_TYPE_P (intype
))
127 intype
= TYPE_MAIN_VARIANT (intype
);
129 if (TYPE_MAIN_VARIANT (type
) != intype
130 && TREE_CODE (type
) == POINTER_TYPE
131 && TREE_CODE (TREE_TYPE (type
)) == RECORD_TYPE
132 && IS_AGGR_TYPE (TREE_TYPE (type
))
133 && IS_AGGR_TYPE (TREE_TYPE (intype
))
134 && TREE_CODE (TREE_TYPE (intype
)) == RECORD_TYPE
)
136 enum tree_code code
= PLUS_EXPR
;
142 intype_class
= TREE_TYPE (intype
);
143 type_class
= TREE_TYPE (type
);
145 same_p
= same_type_p (TYPE_MAIN_VARIANT (intype_class
),
146 TYPE_MAIN_VARIANT (type_class
));
148 /* Try derived to base conversion. */
150 binfo
= lookup_base (intype_class
, type_class
, ba_check
, NULL
);
151 if (!same_p
&& !binfo
)
153 /* Try base to derived conversion. */
154 binfo
= lookup_base (type_class
, intype_class
, ba_check
, NULL
);
157 if (binfo
== error_mark_node
)
158 return error_mark_node
;
162 expr
= build_base_path (code
, expr
, binfo
, 0);
163 /* Add any qualifier conversions. */
164 return build_nop (type
, expr
);
168 if (TYPE_PTRMEMFUNC_P (type
))
170 error ("cannot convert %qE from type %qT to type %qT",
172 return error_mark_node
;
175 return build_nop (type
, expr
);
177 else if (TYPE_PTRMEM_P (type
) && TYPE_PTRMEM_P (intype
))
182 enum tree_code code
= PLUS_EXPR
;
185 b1
= TYPE_PTRMEM_CLASS_TYPE (type
);
186 b2
= TYPE_PTRMEM_CLASS_TYPE (intype
);
187 binfo
= lookup_base (b1
, b2
, ba_check
, &bk
);
190 binfo
= lookup_base (b2
, b1
, ba_check
, &bk
);
193 if (binfo
== error_mark_node
)
194 return error_mark_node
;
196 if (bk
== bk_via_virtual
)
199 warning (0, "pointer to member cast from %qT to %qT is via"
200 " virtual base", intype
, type
);
203 error ("pointer to member cast from %qT to %qT is"
204 " via virtual base", intype
, type
);
205 return error_mark_node
;
207 /* This is a reinterpret cast, whose result is unspecified.
208 We choose to do nothing. */
209 return build1 (NOP_EXPR
, type
, expr
);
212 if (TREE_CODE (expr
) == PTRMEM_CST
)
213 expr
= cplus_expand_constant (expr
);
215 if (binfo
&& !integer_zerop (BINFO_OFFSET (binfo
)))
216 expr
= size_binop (code
,
217 build_nop (sizetype
, expr
),
218 BINFO_OFFSET (binfo
));
219 return build_nop (type
, expr
);
221 else if (TYPE_PTRMEMFUNC_P (type
) && TYPE_PTRMEMFUNC_P (intype
))
222 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), expr
, 0,
224 else if (TYPE_PTRMEMFUNC_P (intype
))
228 if (TREE_CODE (expr
) == PTRMEM_CST
)
229 return cp_convert_to_pointer (type
,
230 PTRMEM_CST_MEMBER (expr
),
232 else if (TREE_CODE (expr
) == OFFSET_REF
)
234 tree object
= TREE_OPERAND (expr
, 0);
235 return get_member_function_from_ptrfunc (&object
,
236 TREE_OPERAND (expr
, 1));
239 error ("cannot convert %qE from type %qT to type %qT",
241 return error_mark_node
;
244 if (integer_zerop (expr
))
246 if (TYPE_PTRMEMFUNC_P (type
))
247 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), expr
, 0,
250 if (TYPE_PTRMEM_P (type
))
252 /* A NULL pointer-to-member is represented by -1, not by
254 expr
= build_int_cst_type (type
, -1);
257 expr
= build_int_cst (type
, 0);
261 else if (TYPE_PTR_TO_MEMBER_P (type
) && INTEGRAL_CODE_P (form
))
263 error ("invalid conversion from %qT to %qT", intype
, type
);
264 return error_mark_node
;
267 if (INTEGRAL_CODE_P (form
))
269 if (TYPE_PRECISION (intype
) == POINTER_SIZE
)
270 return build1 (CONVERT_EXPR
, type
, expr
);
271 expr
= cp_convert (c_common_type_for_size (POINTER_SIZE
, 0), expr
);
272 /* Modes may be different but sizes should be the same. There
273 is supposed to be some integral type that is the same width
275 gcc_assert (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr
)))
276 == GET_MODE_SIZE (TYPE_MODE (type
)));
278 return convert_to_pointer (type
, expr
);
281 if (type_unknown_p (expr
))
282 return instantiate_type (type
, expr
, tf_warning_or_error
);
284 error ("cannot convert %qE from type %qT to type %qT",
286 return error_mark_node
;
289 /* Like convert, except permit conversions to take place which
290 are not normally allowed due to access restrictions
291 (such as conversion from sub-type to private super-type). */
294 convert_to_pointer_force (tree type
, tree expr
)
296 tree intype
= TREE_TYPE (expr
);
297 enum tree_code form
= TREE_CODE (intype
);
299 if (form
== POINTER_TYPE
)
301 intype
= TYPE_MAIN_VARIANT (intype
);
303 if (TYPE_MAIN_VARIANT (type
) != intype
304 && TREE_CODE (TREE_TYPE (type
)) == RECORD_TYPE
305 && IS_AGGR_TYPE (TREE_TYPE (type
))
306 && IS_AGGR_TYPE (TREE_TYPE (intype
))
307 && TREE_CODE (TREE_TYPE (intype
)) == RECORD_TYPE
)
309 enum tree_code code
= PLUS_EXPR
;
312 binfo
= lookup_base (TREE_TYPE (intype
), TREE_TYPE (type
),
316 binfo
= lookup_base (TREE_TYPE (type
), TREE_TYPE (intype
),
320 if (binfo
== error_mark_node
)
321 return error_mark_node
;
324 expr
= build_base_path (code
, expr
, binfo
, 0);
325 if (expr
== error_mark_node
)
326 return error_mark_node
;
327 /* Add any qualifier conversions. */
328 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr
)),
330 expr
= build_nop (type
, expr
);
336 return cp_convert_to_pointer (type
, expr
, true);
339 /* We are passing something to a function which requires a reference.
340 The type we are interested in is in TYPE. The initial
341 value we have to begin with is in ARG.
343 FLAGS controls how we manage access checking.
344 DIRECT_BIND in FLAGS controls how any temporaries are generated.
345 If DIRECT_BIND is set, DECL is the reference we're binding to. */
348 build_up_reference (tree type
, tree arg
, int flags
, tree decl
)
351 tree argtype
= TREE_TYPE (arg
);
352 tree target_type
= TREE_TYPE (type
);
354 gcc_assert (TREE_CODE (type
) == REFERENCE_TYPE
);
356 if ((flags
& DIRECT_BIND
) && ! real_lvalue_p (arg
))
358 /* Create a new temporary variable. We can't just use a TARGET_EXPR
359 here because it needs to live as long as DECL. */
362 arg
= make_temporary_var_for_ref_to_temp (decl
, TREE_TYPE (arg
));
364 /* Process the initializer for the declaration. */
365 DECL_INITIAL (arg
) = targ
;
366 cp_finish_decl (arg
, targ
, /*init_const_expr_p=*/false, NULL_TREE
,
367 LOOKUP_ONLYCONVERTING
|DIRECT_BIND
);
369 else if (!(flags
& DIRECT_BIND
) && ! lvalue_p (arg
))
370 return get_target_expr (arg
);
372 /* If we had a way to wrap this up, and say, if we ever needed its
373 address, transform all occurrences of the register, into a memory
374 reference we could win better. */
375 rval
= build_unary_op (ADDR_EXPR
, arg
, 1);
376 if (rval
== error_mark_node
)
377 return error_mark_node
;
379 if ((flags
& LOOKUP_PROTECT
)
380 && TYPE_MAIN_VARIANT (argtype
) != TYPE_MAIN_VARIANT (target_type
)
381 && IS_AGGR_TYPE (argtype
)
382 && IS_AGGR_TYPE (target_type
))
384 /* We go through lookup_base for the access control. */
385 tree binfo
= lookup_base (argtype
, target_type
, ba_check
, NULL
);
386 if (binfo
== error_mark_node
)
387 return error_mark_node
;
388 if (binfo
== NULL_TREE
)
389 return error_not_base_type (target_type
, argtype
);
390 rval
= build_base_path (PLUS_EXPR
, rval
, binfo
, 1);
394 = convert_to_pointer_force (build_pointer_type (target_type
), rval
);
395 return build_nop (type
, rval
);
398 /* Subroutine of convert_to_reference. REFTYPE is the target reference type.
399 INTYPE is the original rvalue type and DECL is an optional _DECL node
402 [dcl.init.ref] says that if an rvalue is used to
403 initialize a reference, then the reference must be to a
404 non-volatile const type. */
407 warn_ref_binding (tree reftype
, tree intype
, tree decl
)
409 tree ttl
= TREE_TYPE (reftype
);
411 if (!CP_TYPE_CONST_NON_VOLATILE_P (ttl
))
415 if (CP_TYPE_VOLATILE_P (ttl
) && decl
)
416 msg
= "initialization of volatile reference type %q#T from"
417 " rvalue of type %qT";
418 else if (CP_TYPE_VOLATILE_P (ttl
))
419 msg
= "conversion to volatile reference type %q#T "
420 " from rvalue of type %qT";
422 msg
= "initialization of non-const reference type %q#T from"
423 " rvalue of type %qT";
425 msg
= "conversion to non-const reference type %q#T from"
426 " rvalue of type %qT";
428 pedwarn (msg
, reftype
, intype
);
432 /* For C++: Only need to do one-level references, but cannot
433 get tripped up on signed/unsigned differences.
435 DECL is either NULL_TREE or the _DECL node for a reference that is being
436 initialized. It can be error_mark_node if we don't know the _DECL but
437 we know it's an initialization. */
440 convert_to_reference (tree reftype
, tree expr
, int convtype
,
441 int flags
, tree decl
)
443 tree type
= TYPE_MAIN_VARIANT (TREE_TYPE (reftype
));
445 tree rval
= NULL_TREE
;
446 tree rval_as_conversion
= NULL_TREE
;
447 bool can_convert_intype_to_type
;
449 if (TREE_CODE (type
) == FUNCTION_TYPE
450 && TREE_TYPE (expr
) == unknown_type_node
)
451 expr
= instantiate_type (type
, expr
,
452 (flags
& LOOKUP_COMPLAIN
)
453 ? tf_warning_or_error
: tf_none
);
455 if (expr
== error_mark_node
)
456 return error_mark_node
;
458 intype
= TREE_TYPE (expr
);
460 gcc_assert (TREE_CODE (intype
) != REFERENCE_TYPE
);
461 gcc_assert (TREE_CODE (reftype
) == REFERENCE_TYPE
);
463 intype
= TYPE_MAIN_VARIANT (intype
);
465 can_convert_intype_to_type
= can_convert (type
, intype
);
466 if (!can_convert_intype_to_type
467 && (convtype
& CONV_IMPLICIT
) && IS_AGGR_TYPE (intype
)
468 && ! (flags
& LOOKUP_NO_CONVERSION
))
470 /* Look for a user-defined conversion to lvalue that we can use. */
473 = build_type_conversion (reftype
, expr
);
475 if (rval_as_conversion
&& rval_as_conversion
!= error_mark_node
476 && real_lvalue_p (rval_as_conversion
))
478 expr
= rval_as_conversion
;
479 rval_as_conversion
= NULL_TREE
;
481 can_convert_intype_to_type
= 1;
485 if (((convtype
& CONV_STATIC
) && can_convert (intype
, type
))
486 || ((convtype
& CONV_IMPLICIT
) && can_convert_intype_to_type
))
488 if (flags
& LOOKUP_COMPLAIN
)
490 tree ttl
= TREE_TYPE (reftype
);
491 tree ttr
= lvalue_type (expr
);
493 if (! real_lvalue_p (expr
))
494 warn_ref_binding (reftype
, intype
, decl
);
496 if (! (convtype
& CONV_CONST
)
497 && !at_least_as_qualified_p (ttl
, ttr
))
498 pedwarn ("conversion from %qT to %qT discards qualifiers",
502 return build_up_reference (reftype
, expr
, flags
, decl
);
504 else if ((convtype
& CONV_REINTERPRET
) && lvalue_p (expr
))
506 /* When casting an lvalue to a reference type, just convert into
507 a pointer to the new type and deference it. This is allowed
508 by San Diego WP section 5.2.9 paragraph 12, though perhaps it
509 should be done directly (jason). (int &)ri ---> *(int*)&ri */
511 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
513 if (TREE_CODE (intype
) == POINTER_TYPE
514 && (comptypes (TREE_TYPE (intype
), type
,
515 COMPARE_BASE
| COMPARE_DERIVED
)))
516 warning (0, "casting %qT to %qT does not dereference pointer",
519 rval
= build_unary_op (ADDR_EXPR
, expr
, 0);
520 if (rval
!= error_mark_node
)
521 rval
= convert_force (build_pointer_type (TREE_TYPE (reftype
)),
523 if (rval
!= error_mark_node
)
524 rval
= build1 (NOP_EXPR
, reftype
, rval
);
528 rval
= convert_for_initialization (NULL_TREE
, type
, expr
, flags
,
530 if (rval
== NULL_TREE
|| rval
== error_mark_node
)
532 warn_ref_binding (reftype
, intype
, decl
);
533 rval
= build_up_reference (reftype
, rval
, flags
, decl
);
538 /* If we found a way to convert earlier, then use it. */
542 if (flags
& LOOKUP_COMPLAIN
)
543 error ("cannot convert type %qT to type %qT", intype
, reftype
);
545 return error_mark_node
;
548 /* We are using a reference VAL for its value. Bash that reference all the
549 way down to its lowest form. */
552 convert_from_reference (tree val
)
554 if (TREE_CODE (TREE_TYPE (val
)) == REFERENCE_TYPE
)
556 tree t
= canonical_type_variant (TREE_TYPE (TREE_TYPE (val
)));
557 tree ref
= build1 (INDIRECT_REF
, t
, val
);
559 /* We *must* set TREE_READONLY when dereferencing a pointer to const,
560 so that we get the proper error message if the result is used
561 to assign to. Also, &* is supposed to be a no-op. */
562 TREE_READONLY (ref
) = CP_TYPE_CONST_P (t
);
563 TREE_THIS_VOLATILE (ref
) = CP_TYPE_VOLATILE_P (t
);
564 TREE_SIDE_EFFECTS (ref
)
565 = (TREE_THIS_VOLATILE (ref
) || TREE_SIDE_EFFECTS (val
));
566 REFERENCE_REF_P (ref
) = 1;
573 /* Really perform an lvalue-to-rvalue conversion, including copying an
574 argument of class type into a temporary. */
577 force_rvalue (tree expr
)
579 if (IS_AGGR_TYPE (TREE_TYPE (expr
)) && TREE_CODE (expr
) != TARGET_EXPR
)
580 expr
= ocp_convert (TREE_TYPE (expr
), expr
,
581 CONV_IMPLICIT
|CONV_FORCE_TEMP
, LOOKUP_NORMAL
);
583 expr
= decay_conversion (expr
);
588 /* C++ conversions, preference to static cast conversions. */
591 cp_convert (tree type
, tree expr
)
593 return ocp_convert (type
, expr
, CONV_OLD_CONVERT
, LOOKUP_NORMAL
);
598 FLAGS indicates how we should behave. */
601 ocp_convert (tree type
, tree expr
, int convtype
, int flags
)
604 enum tree_code code
= TREE_CODE (type
);
605 const char *invalid_conv_diag
;
607 if (error_operand_p (e
) || type
== error_mark_node
)
608 return error_mark_node
;
610 complete_type (type
);
611 complete_type (TREE_TYPE (expr
));
613 if ((invalid_conv_diag
614 = targetm
.invalid_conversion (TREE_TYPE (expr
), type
)))
616 error (invalid_conv_diag
);
617 return error_mark_node
;
620 e
= integral_constant_value (e
);
622 if (IS_AGGR_TYPE (type
) && (convtype
& CONV_FORCE_TEMP
)
623 /* Some internal structures (vtable_entry_type, sigtbl_ptr_type)
624 don't go through finish_struct, so they don't have the synthesized
625 constructors. So don't force a temporary. */
626 && TYPE_HAS_CONSTRUCTOR (type
))
627 /* We need a new temporary; don't take this shortcut. */;
628 else if (TYPE_MAIN_VARIANT (type
) == TYPE_MAIN_VARIANT (TREE_TYPE (e
)))
630 if (same_type_p (type
, TREE_TYPE (e
)))
631 /* The call to fold will not always remove the NOP_EXPR as
632 might be expected, since if one of the types is a typedef;
633 the comparison in fold is just equality of pointers, not a
634 call to comptypes. We don't call fold in this case because
635 that can result in infinite recursion; fold will call
636 convert, which will call ocp_convert, etc. */
638 /* For complex data types, we need to perform componentwise
640 else if (TREE_CODE (type
) == COMPLEX_TYPE
)
641 return fold_if_not_in_template (convert_to_complex (type
, e
));
642 else if (TREE_CODE (e
) == TARGET_EXPR
)
644 /* Don't build a NOP_EXPR of class type. Instead, change the
645 type of the temporary. Only allow this for cv-qual changes,
647 gcc_assert (same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (e
)),
648 TYPE_MAIN_VARIANT (type
)));
649 TREE_TYPE (e
) = TREE_TYPE (TARGET_EXPR_SLOT (e
)) = type
;
654 /* We shouldn't be treating objects of ADDRESSABLE type as
656 gcc_assert (!TREE_ADDRESSABLE (type
));
657 return fold_if_not_in_template (build_nop (type
, e
));
661 if (code
== VOID_TYPE
&& (convtype
& CONV_STATIC
))
663 e
= convert_to_void (e
, /*implicit=*/NULL
);
667 if (INTEGRAL_CODE_P (code
))
669 tree intype
= TREE_TYPE (e
);
670 /* enum = enum, enum = int, enum = float, (enum)pointer are all
672 if (TREE_CODE (type
) == ENUMERAL_TYPE
673 && (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype
)
674 || TREE_CODE (intype
) == REAL_TYPE
)
675 && ! (convtype
& CONV_STATIC
))
676 || TREE_CODE (intype
) == POINTER_TYPE
))
678 if (flags
& LOOKUP_COMPLAIN
)
679 pedwarn ("conversion from %q#T to %q#T", intype
, type
);
681 if (flag_pedantic_errors
)
682 return error_mark_node
;
684 if (IS_AGGR_TYPE (intype
))
687 rval
= build_type_conversion (type
, e
);
690 if (flags
& LOOKUP_COMPLAIN
)
691 error ("%q#T used where a %qT was expected", intype
, type
);
692 return error_mark_node
;
694 if (code
== BOOLEAN_TYPE
)
695 return cp_truthvalue_conversion (e
);
697 return fold_if_not_in_template (convert_to_integer (type
, e
));
699 if (POINTER_TYPE_P (type
) || TYPE_PTR_TO_MEMBER_P (type
))
700 return fold_if_not_in_template (cp_convert_to_pointer (type
, e
, false));
701 if (code
== VECTOR_TYPE
)
703 tree in_vtype
= TREE_TYPE (e
);
704 if (IS_AGGR_TYPE (in_vtype
))
707 ret_val
= build_type_conversion (type
, e
);
710 if (flags
& LOOKUP_COMPLAIN
)
711 error ("%q#T used where a %qT was expected", in_vtype
, type
);
712 return error_mark_node
;
714 return fold_if_not_in_template (convert_to_vector (type
, e
));
716 if (code
== REAL_TYPE
|| code
== COMPLEX_TYPE
)
718 if (IS_AGGR_TYPE (TREE_TYPE (e
)))
721 rval
= build_type_conversion (type
, e
);
725 if (flags
& LOOKUP_COMPLAIN
)
726 error ("%q#T used where a floating point value was expected",
729 if (code
== REAL_TYPE
)
730 return fold_if_not_in_template (convert_to_real (type
, e
));
731 else if (code
== COMPLEX_TYPE
)
732 return fold_if_not_in_template (convert_to_complex (type
, e
));
735 /* New C++ semantics: since assignment is now based on
736 memberwise copying, if the rhs type is derived from the
737 lhs type, then we may still do a conversion. */
738 if (IS_AGGR_TYPE_CODE (code
))
740 tree dtype
= TREE_TYPE (e
);
741 tree ctor
= NULL_TREE
;
743 dtype
= TYPE_MAIN_VARIANT (dtype
);
745 /* Conversion between aggregate types. New C++ semantics allow
746 objects of derived type to be cast to objects of base type.
747 Old semantics only allowed this between pointers.
749 There may be some ambiguity between using a constructor
750 vs. using a type conversion operator when both apply. */
754 if (abstract_virtuals_error (NULL_TREE
, type
))
755 return error_mark_node
;
757 if ((flags
& LOOKUP_ONLYCONVERTING
)
758 && ! (IS_AGGR_TYPE (dtype
) && DERIVED_FROM_P (type
, dtype
)))
759 /* For copy-initialization, first we create a temp of the proper type
760 with a user-defined conversion sequence, then we direct-initialize
761 the target with the temp (see [dcl.init]). */
762 ctor
= build_user_type_conversion (type
, ctor
, flags
);
764 ctor
= build_special_member_call (NULL_TREE
,
765 complete_ctor_identifier
,
766 build_tree_list (NULL_TREE
, ctor
),
769 return build_cplus_new (type
, ctor
);
772 if (flags
& LOOKUP_COMPLAIN
)
773 error ("conversion from %qT to non-scalar type %qT requested",
774 TREE_TYPE (expr
), type
);
775 return error_mark_node
;
778 /* When an expression is used in a void context, its value is discarded and
779 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
780 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
781 in a void context. The C++ standard does not define what an `access' to an
782 object is, but there is reason to believe that it is the lvalue to rvalue
783 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
784 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
785 indicates that volatile semantics should be the same between C and C++
786 where ever possible. C leaves it implementation defined as to what
787 constitutes an access to a volatile. So, we interpret `*vp' as a read of
788 the volatile object `vp' points to, unless that is an incomplete type. For
789 volatile references we do not do this interpretation, because that would
790 make it impossible to ignore the reference return value from functions. We
791 issue warnings in the confusing cases.
793 IMPLICIT is tells us the context of an implicit void conversion. */
796 convert_to_void (tree expr
, const char *implicit
)
798 if (expr
== error_mark_node
799 || TREE_TYPE (expr
) == error_mark_node
)
800 return error_mark_node
;
801 if (!TREE_TYPE (expr
))
803 if (invalid_nonstatic_memfn_p (expr
))
804 return error_mark_node
;
805 if (TREE_CODE (expr
) == PSEUDO_DTOR_EXPR
)
807 error ("pseudo-destructor is not called");
808 return error_mark_node
;
810 if (VOID_TYPE_P (TREE_TYPE (expr
)))
812 switch (TREE_CODE (expr
))
816 /* The two parts of a cond expr might be separate lvalues. */
817 tree op1
= TREE_OPERAND (expr
,1);
818 tree op2
= TREE_OPERAND (expr
,2);
819 tree new_op1
= convert_to_void
820 (op1
, (implicit
&& !TREE_SIDE_EFFECTS (op2
)
821 ? "second operand of conditional" : NULL
));
822 tree new_op2
= convert_to_void
823 (op2
, (implicit
&& !TREE_SIDE_EFFECTS (op1
)
824 ? "third operand of conditional" : NULL
));
826 expr
= build3 (COND_EXPR
, TREE_TYPE (new_op1
),
827 TREE_OPERAND (expr
, 0), new_op1
, new_op2
);
833 /* The second part of a compound expr contains the value. */
834 tree op1
= TREE_OPERAND (expr
,1);
835 tree new_op1
= convert_to_void
836 (op1
, (implicit
&& !TREE_NO_WARNING (expr
)
837 ? "right-hand operand of comma" : NULL
));
841 tree t
= build2 (COMPOUND_EXPR
, TREE_TYPE (new_op1
),
842 TREE_OPERAND (expr
, 0), new_op1
);
849 case NON_LVALUE_EXPR
:
851 /* These have already decayed to rvalue. */
854 case CALL_EXPR
: /* We have a special meaning for volatile void fn(). */
859 tree type
= TREE_TYPE (expr
);
860 int is_reference
= TREE_CODE (TREE_TYPE (TREE_OPERAND (expr
, 0)))
862 int is_volatile
= TYPE_VOLATILE (type
);
863 int is_complete
= COMPLETE_TYPE_P (complete_type (type
));
865 /* Can't load the value if we don't know the type. */
866 if (is_volatile
&& !is_complete
)
867 warning (0, "object of incomplete type %qT will not be accessed in %s",
868 type
, implicit
? implicit
: "void context");
869 /* Don't load the value if this is an implicit dereference, or if
870 the type needs to be handled by ctors/dtors. */
871 else if (is_volatile
&& (is_reference
|| TREE_ADDRESSABLE (type
)))
872 warning (0, "object of type %qT will not be accessed in %s",
873 TREE_TYPE (TREE_OPERAND (expr
, 0)),
874 implicit
? implicit
: "void context");
875 if (is_reference
|| !is_volatile
|| !is_complete
|| TREE_ADDRESSABLE (type
))
876 expr
= TREE_OPERAND (expr
, 0);
883 /* External variables might be incomplete. */
884 tree type
= TREE_TYPE (expr
);
885 int is_complete
= COMPLETE_TYPE_P (complete_type (type
));
887 if (TYPE_VOLATILE (type
) && !is_complete
)
888 warning (0, "object %qE of incomplete type %qT will not be accessed in %s",
889 expr
, type
, implicit
? implicit
: "void context");
894 /* Don't bother with the temporary object returned from a function if
895 we don't use it and don't need to destroy it. We'll still
896 allocate space for it in expand_call or declare_return_variable,
897 but we don't need to track it through all the tree phases. */
898 if (TARGET_EXPR_IMPLICIT_P (expr
)
899 && TYPE_HAS_TRIVIAL_DESTRUCTOR (TREE_TYPE (expr
)))
901 tree init
= TARGET_EXPR_INITIAL (expr
);
902 if (TREE_CODE (init
) == AGGR_INIT_EXPR
903 && !AGGR_INIT_VIA_CTOR_P (init
))
905 tree fn
= AGGR_INIT_EXPR_FN (init
);
906 expr
= build_call_array (TREE_TYPE (TREE_TYPE (TREE_TYPE (fn
))),
908 aggr_init_expr_nargs (init
),
909 AGGR_INIT_EXPR_ARGP (init
));
919 if (TREE_CODE (probe
) == ADDR_EXPR
)
920 probe
= TREE_OPERAND (expr
, 0);
921 if (type_unknown_p (probe
))
923 /* [over.over] enumerates the places where we can take the address
924 of an overloaded function, and this is not one of them. */
925 pedwarn ("%s cannot resolve address of overloaded function",
926 implicit
? implicit
: "void cast");
927 expr
= void_zero_node
;
929 else if (implicit
&& probe
== expr
&& is_overloaded_fn (probe
))
931 /* Only warn when there is no &. */
932 warning (0, "%s is a reference, not call, to function %qE",
934 if (TREE_CODE (expr
) == COMPONENT_REF
)
935 expr
= TREE_OPERAND (expr
, 0);
939 if (expr
!= error_mark_node
&& !VOID_TYPE_P (TREE_TYPE (expr
)))
943 && !TREE_NO_WARNING (expr
)
944 && !processing_template_decl
)
946 /* The middle end does not warn about expressions that have
947 been explicitly cast to void, so we must do so here. */
948 if (!TREE_SIDE_EFFECTS (expr
))
949 warning (OPT_Wunused_value
, "%s has no effect", implicit
);
954 enum tree_code_class
class;
957 /* We might like to warn about (say) "(int) f()", as the
958 cast has no effect, but the compiler itself will
959 generate implicit conversions under some
960 circumstances. (For example a block copy will be
961 turned into a call to "__builtin_memcpy", with a
962 conversion of the return value to an appropriate
963 type.) So, to avoid false positives, we strip
964 conversions. Do not use STRIP_NOPs because it will
965 not strip conversions to "void", as that is not a
966 mode-preserving conversion. */
967 while (TREE_CODE (e
) == NOP_EXPR
)
968 e
= TREE_OPERAND (e
, 0);
970 code
= TREE_CODE (e
);
971 class = TREE_CODE_CLASS (code
);
972 if (class == tcc_comparison
973 || class == tcc_unary
974 || (class == tcc_binary
975 && !(code
== MODIFY_EXPR
977 || code
== PREDECREMENT_EXPR
978 || code
== PREINCREMENT_EXPR
979 || code
== POSTDECREMENT_EXPR
980 || code
== POSTINCREMENT_EXPR
)))
981 warning (OPT_Wunused_value
, "value computed is not used");
984 expr
= build1 (CONVERT_EXPR
, void_type_node
, expr
);
986 if (! TREE_SIDE_EFFECTS (expr
))
987 expr
= void_zero_node
;
991 /* Create an expression whose value is that of EXPR,
992 converted to type TYPE. The TREE_TYPE of the value
993 is always TYPE. This function implements all reasonable
994 conversions; callers should filter out those that are
995 not permitted by the language being compiled.
997 Most of this routine is from build_reinterpret_cast.
999 The back end cannot call cp_convert (what was convert) because
1000 conversions to/from basetypes may involve memory references
1001 (vbases) and adding or subtracting small values (multiple
1002 inheritance), but it calls convert from the constant folding code
1003 on subtrees of already built trees after it has ripped them apart.
1005 Also, if we ever support range variables, we'll probably also have to
1006 do a little bit more work. */
1009 convert (tree type
, tree expr
)
1013 if (type
== error_mark_node
|| expr
== error_mark_node
)
1014 return error_mark_node
;
1016 intype
= TREE_TYPE (expr
);
1018 if (POINTER_TYPE_P (type
) && POINTER_TYPE_P (intype
))
1019 return fold_if_not_in_template (build_nop (type
, expr
));
1021 return ocp_convert (type
, expr
, CONV_OLD_CONVERT
,
1022 LOOKUP_NORMAL
|LOOKUP_NO_CONVERSION
);
1025 /* Like cp_convert, except permit conversions to take place which
1026 are not normally allowed due to access restrictions
1027 (such as conversion from sub-type to private super-type). */
1030 convert_force (tree type
, tree expr
, int convtype
)
1033 enum tree_code code
= TREE_CODE (type
);
1035 if (code
== REFERENCE_TYPE
)
1036 return (fold_if_not_in_template
1037 (convert_to_reference (type
, e
, CONV_C_CAST
, LOOKUP_COMPLAIN
,
1040 if (code
== POINTER_TYPE
)
1041 return fold_if_not_in_template (convert_to_pointer_force (type
, e
));
1043 /* From typeck.c convert_for_assignment */
1044 if (((TREE_CODE (TREE_TYPE (e
)) == POINTER_TYPE
&& TREE_CODE (e
) == ADDR_EXPR
1045 && TREE_CODE (TREE_TYPE (e
)) == POINTER_TYPE
1046 && TREE_CODE (TREE_TYPE (TREE_TYPE (e
))) == METHOD_TYPE
)
1047 || integer_zerop (e
)
1048 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e
)))
1049 && TYPE_PTRMEMFUNC_P (type
))
1050 /* compatible pointer to member functions. */
1051 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), e
, 1,
1054 return ocp_convert (type
, e
, CONV_C_CAST
|convtype
, LOOKUP_NORMAL
);
1057 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1058 exists, return the attempted conversion. This may
1059 return ERROR_MARK_NODE if the conversion is not
1060 allowed (references private members, etc).
1061 If no conversion exists, NULL_TREE is returned.
1063 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1064 object parameter, or by the second standard conversion sequence if
1065 that doesn't do it. This will probably wait for an overloading rewrite.
1069 build_type_conversion (tree xtype
, tree expr
)
1071 /* C++: check to see if we can convert this aggregate type
1072 into the required type. */
1073 return build_user_type_conversion (xtype
, expr
, LOOKUP_NORMAL
);
1076 /* Convert the given EXPR to one of a group of types suitable for use in an
1077 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1078 which indicates which types are suitable. If COMPLAIN is true, complain
1079 about ambiguity; otherwise, the caller will deal with it. */
1082 build_expr_type_conversion (int desires
, tree expr
, bool complain
)
1084 tree basetype
= TREE_TYPE (expr
);
1085 tree conv
= NULL_TREE
;
1086 tree winner
= NULL_TREE
;
1088 if (expr
== null_node
1089 && (desires
& WANT_INT
)
1090 && !(desires
& WANT_NULL
))
1091 warning (OPT_Wconversion
, "converting NULL to non-pointer type");
1093 basetype
= TREE_TYPE (expr
);
1095 if (basetype
== error_mark_node
)
1096 return error_mark_node
;
1098 if (! IS_AGGR_TYPE (basetype
))
1099 switch (TREE_CODE (basetype
))
1102 if ((desires
& WANT_NULL
) && null_ptr_cst_p (expr
))
1104 /* else fall through... */
1107 return (desires
& WANT_INT
) ? expr
: NULL_TREE
;
1109 return (desires
& WANT_ENUM
) ? expr
: NULL_TREE
;
1111 return (desires
& WANT_FLOAT
) ? expr
: NULL_TREE
;
1113 return (desires
& WANT_POINTER
) ? expr
: NULL_TREE
;
1117 return (desires
& WANT_POINTER
) ? decay_conversion (expr
)
1121 if ((desires
& WANT_VECTOR
) == 0)
1123 switch (TREE_CODE (TREE_TYPE (basetype
)))
1127 return (desires
& WANT_INT
) ? expr
: NULL_TREE
;
1129 return (desires
& WANT_ENUM
) ? expr
: NULL_TREE
;
1131 return (desires
& WANT_FLOAT
) ? expr
: NULL_TREE
;
1140 /* The code for conversions from class type is currently only used for
1141 delete expressions. Other expressions are handled by build_new_op. */
1142 if (!complete_type_or_else (basetype
, expr
))
1143 return error_mark_node
;
1144 if (!TYPE_HAS_CONVERSION (basetype
))
1147 for (conv
= lookup_conversions (basetype
); conv
; conv
= TREE_CHAIN (conv
))
1151 tree cand
= TREE_VALUE (conv
);
1153 if (winner
&& winner
== cand
)
1156 candidate
= non_reference (TREE_TYPE (TREE_TYPE (cand
)));
1158 switch (TREE_CODE (candidate
))
1162 win
= (desires
& WANT_INT
); break;
1164 win
= (desires
& WANT_ENUM
); break;
1166 win
= (desires
& WANT_FLOAT
); break;
1168 win
= (desires
& WANT_POINTER
); break;
1171 if ((desires
& WANT_VECTOR
) == 0)
1173 switch (TREE_CODE (TREE_TYPE (candidate
)))
1177 win
= (desires
& WANT_INT
); break;
1179 win
= (desires
& WANT_ENUM
); break;
1181 win
= (desires
& WANT_FLOAT
); break;
1197 error ("ambiguous default type conversion from %qT",
1199 error (" candidate conversions include %qD and %qD",
1202 return error_mark_node
;
1211 tree type
= non_reference (TREE_TYPE (TREE_TYPE (winner
)));
1212 return build_user_type_conversion (type
, expr
, LOOKUP_NORMAL
);
1218 /* Implements integral promotion (4.1) and float->double promotion. */
1221 type_promotes_to (tree type
)
1223 if (type
== error_mark_node
)
1224 return error_mark_node
;
1226 type
= TYPE_MAIN_VARIANT (type
);
1228 /* bool always promotes to int (not unsigned), even if it's the same
1230 if (type
== boolean_type_node
)
1231 type
= integer_type_node
;
1233 /* Normally convert enums to int, but convert wide enums to something
1235 else if (TREE_CODE (type
) == ENUMERAL_TYPE
1236 || type
== wchar_type_node
)
1238 int precision
= MAX (TYPE_PRECISION (type
),
1239 TYPE_PRECISION (integer_type_node
));
1240 tree totype
= c_common_type_for_size (precision
, 0);
1241 if (TYPE_UNSIGNED (type
)
1242 && ! int_fits_type_p (TYPE_MAX_VALUE (type
), totype
))
1243 type
= c_common_type_for_size (precision
, 1);
1247 else if (c_promoting_integer_type_p (type
))
1249 /* Retain unsignedness if really not getting bigger. */
1250 if (TYPE_UNSIGNED (type
)
1251 && TYPE_PRECISION (type
) == TYPE_PRECISION (integer_type_node
))
1252 type
= unsigned_type_node
;
1254 type
= integer_type_node
;
1256 else if (type
== float_type_node
)
1257 type
= double_type_node
;
1262 /* The routines below this point are carefully written to conform to
1263 the standard. They use the same terminology, and follow the rules
1264 closely. Although they are used only in pt.c at the moment, they
1265 should presumably be used everywhere in the future. */
1267 /* Attempt to perform qualification conversions on EXPR to convert it
1268 to TYPE. Return the resulting expression, or error_mark_node if
1269 the conversion was impossible. */
1272 perform_qualification_conversions (tree type
, tree expr
)
1276 expr_type
= TREE_TYPE (expr
);
1278 if (same_type_p (type
, expr_type
))
1280 else if (TYPE_PTR_P (type
) && TYPE_PTR_P (expr_type
)
1281 && comp_ptr_ttypes (TREE_TYPE (type
), TREE_TYPE (expr_type
)))
1282 return build_nop (type
, expr
);
1283 else if (TYPE_PTR_TO_MEMBER_P (type
)
1284 && TYPE_PTR_TO_MEMBER_P (expr_type
)
1285 && same_type_p (TYPE_PTRMEM_CLASS_TYPE (type
),
1286 TYPE_PTRMEM_CLASS_TYPE (expr_type
))
1287 && comp_ptr_ttypes (TYPE_PTRMEM_POINTED_TO_TYPE (type
),
1288 TYPE_PTRMEM_POINTED_TO_TYPE (expr_type
)))
1289 return build_nop (type
, expr
);
1291 return error_mark_node
;