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 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, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, 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"
40 static tree
cp_convert_to_pointer (tree
, tree
, bool);
41 static tree
convert_to_pointer_force (tree
, tree
);
42 static tree
build_up_reference (tree
, tree
, int, tree
);
43 static void warn_ref_binding (tree
, tree
, tree
);
45 /* Change of width--truncation and extension of integers or reals--
46 is represented with NOP_EXPR. Proper functioning of many things
47 assumes that no other conversions can be NOP_EXPRs.
49 Conversion between integer and pointer is represented with CONVERT_EXPR.
50 Converting integer to real uses FLOAT_EXPR
51 and real to integer uses FIX_TRUNC_EXPR.
53 Here is a list of all the functions that assume that widening and
54 narrowing is always done with a NOP_EXPR:
55 In convert.c, convert_to_integer.
56 In c-typeck.c, build_binary_op_nodefault (boolean ops),
57 and c_common_truthvalue_conversion.
58 In expr.c: expand_expr, for operands of a MULT_EXPR.
59 In fold-const.c: fold.
60 In tree.c: get_narrower and get_unwidened.
62 C++: in multiple-inheritance, converting between pointers may involve
63 adjusting them by a delta stored within the class definition. */
65 /* Subroutines of `convert'. */
67 /* if converting pointer to pointer
68 if dealing with classes, check for derived->base or vice versa
69 else if dealing with method pointers, delegate
71 else if converting class, pass off to build_type_conversion
72 else try C-style pointer conversion. If FORCE is true then allow
73 conversions via virtual bases (these are permitted by reinterpret_cast,
74 but not static_cast). */
77 cp_convert_to_pointer (tree type
, tree expr
, bool force
)
79 register tree intype
= TREE_TYPE (expr
);
80 register enum tree_code form
;
83 if (IS_AGGR_TYPE (intype
))
85 intype
= complete_type (intype
);
86 if (!COMPLETE_TYPE_P (intype
))
88 error ("can't convert from incomplete type `%T' to `%T'",
90 return error_mark_node
;
93 rval
= build_type_conversion (type
, expr
);
96 if (rval
== error_mark_node
)
97 error ("conversion of `%E' from `%T' to `%T' is ambiguous",
103 /* Handle anachronistic conversions from (::*)() to cv void* or (*)(). */
104 if (TREE_CODE (type
) == POINTER_TYPE
105 && (TREE_CODE (TREE_TYPE (type
)) == FUNCTION_TYPE
106 || VOID_TYPE_P (TREE_TYPE (type
))))
108 /* Allow an implicit this pointer for pointer to member
110 if (TYPE_PTRMEMFUNC_P (intype
))
112 if (pedantic
|| warn_pmf2ptr
)
113 pedwarn ("converting from `%T' to `%T'", intype
, type
);
114 if (TREE_CODE (expr
) == PTRMEM_CST
)
115 expr
= build_address (PTRMEM_CST_MEMBER (expr
));
118 tree decl
= maybe_dummy_object (TYPE_PTRMEM_CLASS_TYPE (intype
),
120 decl
= build_address (decl
);
121 expr
= get_member_function_from_ptrfunc (&decl
, expr
);
124 else if (TREE_CODE (TREE_TYPE (expr
)) == METHOD_TYPE
)
126 if (pedantic
|| warn_pmf2ptr
)
127 pedwarn ("converting from `%T' to `%T'", intype
, type
);
128 expr
= build_addr_func (expr
);
130 if (TREE_CODE (TREE_TYPE (expr
)) == POINTER_TYPE
)
131 return build_nop (type
, expr
);
132 intype
= TREE_TYPE (expr
);
135 if (expr
== error_mark_node
)
136 return error_mark_node
;
138 form
= TREE_CODE (intype
);
140 if (POINTER_TYPE_P (intype
))
142 intype
= TYPE_MAIN_VARIANT (intype
);
144 if (TYPE_MAIN_VARIANT (type
) != intype
145 && TREE_CODE (type
) == POINTER_TYPE
146 && TREE_CODE (TREE_TYPE (type
)) == RECORD_TYPE
147 && IS_AGGR_TYPE (TREE_TYPE (type
))
148 && IS_AGGR_TYPE (TREE_TYPE (intype
))
149 && TREE_CODE (TREE_TYPE (intype
)) == RECORD_TYPE
)
151 enum tree_code code
= PLUS_EXPR
;
157 intype_class
= TREE_TYPE (intype
);
158 type_class
= TREE_TYPE (type
);
160 same_p
= same_type_p (TYPE_MAIN_VARIANT (intype_class
),
161 TYPE_MAIN_VARIANT (type_class
));
163 /* Try derived to base conversion. */
165 binfo
= lookup_base (intype_class
, type_class
, ba_check
, NULL
);
166 if (!same_p
&& !binfo
)
168 /* Try base to derived conversion. */
169 binfo
= lookup_base (type_class
, intype_class
, ba_check
, NULL
);
172 if (binfo
== error_mark_node
)
173 return error_mark_node
;
177 expr
= build_base_path (code
, expr
, binfo
, 0);
178 /* Add any qualifier conversions. */
179 return build_nop (type
, expr
);
183 if (TYPE_PTRMEMFUNC_P (type
))
185 error ("cannot convert `%E' from type `%T' to type `%T'",
187 return error_mark_node
;
190 return build_nop (type
, expr
);
192 else if (TYPE_PTRMEM_P (type
) && TYPE_PTRMEM_P (intype
))
197 enum tree_code code
= PLUS_EXPR
;
200 b1
= TYPE_PTRMEM_CLASS_TYPE (type
);
201 b2
= TYPE_PTRMEM_CLASS_TYPE (intype
);
202 binfo
= lookup_base (b1
, b2
, ba_check
, &bk
);
205 binfo
= lookup_base (b2
, b1
, ba_check
, &bk
);
208 if (binfo
== error_mark_node
)
209 return error_mark_node
;
211 if (bk
== bk_via_virtual
)
214 warning ("pointer to member cast from `%T' to `%T' is via virtual base",
218 error ("pointer to member cast from `%T' to `%T' is via virtual base",
220 return error_mark_node
;
222 /* This is a reinterpret cast, whose result is unspecified.
223 We choose to do nothing. */
224 return build1 (NOP_EXPR
, type
, expr
);
227 if (TREE_CODE (expr
) == PTRMEM_CST
)
228 expr
= cplus_expand_constant (expr
);
230 if (binfo
&& !integer_zerop (BINFO_OFFSET (binfo
)))
231 expr
= size_binop (code
,
232 build_nop (sizetype
, expr
),
233 BINFO_OFFSET (binfo
));
234 return build_nop (type
, expr
);
236 else if (TYPE_PTRMEMFUNC_P (type
) && TYPE_PTRMEMFUNC_P (intype
))
237 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), expr
, 0);
238 else if (TYPE_PTRMEMFUNC_P (intype
))
242 if (TREE_CODE (expr
) == PTRMEM_CST
)
243 return cp_convert_to_pointer (type
,
244 PTRMEM_CST_MEMBER (expr
),
246 else if (TREE_CODE (expr
) == OFFSET_REF
)
248 tree object
= TREE_OPERAND (expr
, 0);
249 return get_member_function_from_ptrfunc (&object
,
250 TREE_OPERAND (expr
, 1));
253 error ("cannot convert `%E' from type `%T' to type `%T'",
255 return error_mark_node
;
258 if (integer_zerop (expr
))
260 if (TYPE_PTRMEMFUNC_P (type
))
261 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), expr
, 0);
263 if (TYPE_PTRMEM_P (type
))
264 /* A NULL pointer-to-member is represented by -1, not by
266 expr
= build_int_2 (-1, -1);
268 expr
= build_int_2 (0, 0);
269 TREE_TYPE (expr
) = type
;
270 /* Fix up the representation of -1 if appropriate. */
271 force_fit_type (expr
, 0);
274 else if (TYPE_PTR_TO_MEMBER_P (type
) && INTEGRAL_CODE_P (form
))
276 error ("invalid conversion from '%T' to '%T'", intype
, type
);
277 return error_mark_node
;
280 if (INTEGRAL_CODE_P (form
))
282 if (TYPE_PRECISION (intype
) == POINTER_SIZE
)
283 return build1 (CONVERT_EXPR
, type
, expr
);
284 expr
= cp_convert (c_common_type_for_size (POINTER_SIZE
, 0), expr
);
285 /* Modes may be different but sizes should be the same. */
286 if (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr
)))
287 != GET_MODE_SIZE (TYPE_MODE (type
)))
288 /* There is supposed to be some integral type
289 that is the same width as a pointer. */
291 return convert_to_pointer (type
, expr
);
294 if (type_unknown_p (expr
))
295 return instantiate_type (type
, expr
, tf_error
| tf_warning
);
297 error ("cannot convert `%E' from type `%T' to type `%T'",
299 return error_mark_node
;
302 /* Like convert, except permit conversions to take place which
303 are not normally allowed due to access restrictions
304 (such as conversion from sub-type to private super-type). */
307 convert_to_pointer_force (tree type
, tree expr
)
309 register tree intype
= TREE_TYPE (expr
);
310 register enum tree_code form
= TREE_CODE (intype
);
312 if (form
== POINTER_TYPE
)
314 intype
= TYPE_MAIN_VARIANT (intype
);
316 if (TYPE_MAIN_VARIANT (type
) != intype
317 && TREE_CODE (TREE_TYPE (type
)) == RECORD_TYPE
318 && IS_AGGR_TYPE (TREE_TYPE (type
))
319 && IS_AGGR_TYPE (TREE_TYPE (intype
))
320 && TREE_CODE (TREE_TYPE (intype
)) == RECORD_TYPE
)
322 enum tree_code code
= PLUS_EXPR
;
325 binfo
= lookup_base (TREE_TYPE (intype
), TREE_TYPE (type
),
329 binfo
= lookup_base (TREE_TYPE (type
), TREE_TYPE (intype
),
333 if (binfo
== error_mark_node
)
334 return error_mark_node
;
337 expr
= build_base_path (code
, expr
, binfo
, 0);
338 if (expr
== error_mark_node
)
339 return error_mark_node
;
340 /* Add any qualifier conversions. */
341 if (!same_type_p (TREE_TYPE (TREE_TYPE (expr
)),
343 expr
= build_nop (type
, expr
);
349 return cp_convert_to_pointer (type
, expr
, true);
352 /* We are passing something to a function which requires a reference.
353 The type we are interested in is in TYPE. The initial
354 value we have to begin with is in ARG.
356 FLAGS controls how we manage access checking.
357 DIRECT_BIND in FLAGS controls how any temporaries are generated.
358 If DIRECT_BIND is set, DECL is the reference we're binding to. */
361 build_up_reference (tree type
, tree arg
, int flags
, tree decl
)
364 tree argtype
= TREE_TYPE (arg
);
365 tree target_type
= TREE_TYPE (type
);
367 my_friendly_assert (TREE_CODE (type
) == REFERENCE_TYPE
, 187);
369 if ((flags
& DIRECT_BIND
) && ! real_lvalue_p (arg
))
371 /* Create a new temporary variable. We can't just use a TARGET_EXPR
372 here because it needs to live as long as DECL. */
375 arg
= make_temporary_var_for_ref_to_temp (decl
, TREE_TYPE (arg
));
377 /* Process the initializer for the declaration. */
378 DECL_INITIAL (arg
) = targ
;
379 cp_finish_decl (arg
, targ
, NULL_TREE
,
380 LOOKUP_ONLYCONVERTING
|DIRECT_BIND
);
382 else if (!(flags
& DIRECT_BIND
) && ! lvalue_p (arg
))
383 return get_target_expr (arg
);
385 /* If we had a way to wrap this up, and say, if we ever needed its
386 address, transform all occurrences of the register, into a memory
387 reference we could win better. */
388 rval
= build_unary_op (ADDR_EXPR
, arg
, 1);
389 if (rval
== error_mark_node
)
390 return error_mark_node
;
392 if ((flags
& LOOKUP_PROTECT
)
393 && TYPE_MAIN_VARIANT (argtype
) != TYPE_MAIN_VARIANT (target_type
)
394 && IS_AGGR_TYPE (argtype
)
395 && IS_AGGR_TYPE (target_type
))
397 /* We go through lookup_base for the access control. */
398 tree binfo
= lookup_base (argtype
, target_type
, ba_check
, NULL
);
399 if (binfo
== error_mark_node
)
400 return error_mark_node
;
401 if (binfo
== NULL_TREE
)
402 return error_not_base_type (target_type
, argtype
);
403 rval
= build_base_path (PLUS_EXPR
, rval
, binfo
, 1);
407 = convert_to_pointer_force (build_pointer_type (target_type
), rval
);
408 return build_nop (type
, rval
);
411 /* Subroutine of convert_to_reference. REFTYPE is the target reference type.
412 INTYPE is the original rvalue type and DECL is an optional _DECL node
415 [dcl.init.ref] says that if an rvalue is used to
416 initialize a reference, then the reference must be to a
417 non-volatile const type. */
420 warn_ref_binding (tree reftype
, tree intype
, tree decl
)
422 tree ttl
= TREE_TYPE (reftype
);
424 if (!CP_TYPE_CONST_NON_VOLATILE_P (ttl
))
428 if (CP_TYPE_VOLATILE_P (ttl
) && decl
)
429 msg
= "initialization of volatile reference type `%#T' from rvalue of type `%T'";
430 else if (CP_TYPE_VOLATILE_P (ttl
))
431 msg
= "conversion to volatile reference type `%#T' from rvalue of type `%T'";
433 msg
= "initialization of non-const reference type `%#T' from rvalue of type `%T'";
435 msg
= "conversion to non-const reference type `%#T' from rvalue of type `%T'";
437 pedwarn (msg
, reftype
, intype
);
441 /* For C++: Only need to do one-level references, but cannot
442 get tripped up on signed/unsigned differences.
444 DECL is either NULL_TREE or the _DECL node for a reference that is being
445 initialized. It can be error_mark_node if we don't know the _DECL but
446 we know it's an initialization. */
449 convert_to_reference (tree reftype
, tree expr
, int convtype
,
450 int flags
, tree decl
)
452 register tree type
= TYPE_MAIN_VARIANT (TREE_TYPE (reftype
));
453 register tree intype
;
454 tree rval
= NULL_TREE
;
455 tree rval_as_conversion
= NULL_TREE
;
456 bool can_convert_intype_to_type
;
458 if (TREE_CODE (type
) == FUNCTION_TYPE
459 && TREE_TYPE (expr
) == unknown_type_node
)
460 expr
= instantiate_type (type
, expr
,
461 (flags
& LOOKUP_COMPLAIN
)
462 ? tf_error
| tf_warning
: tf_none
);
464 expr
= convert_from_reference (expr
);
466 if (expr
== error_mark_node
)
467 return error_mark_node
;
469 intype
= TREE_TYPE (expr
);
471 my_friendly_assert (TREE_CODE (intype
) != REFERENCE_TYPE
, 364);
473 intype
= TYPE_MAIN_VARIANT (intype
);
475 can_convert_intype_to_type
= can_convert (type
, intype
);
476 if (!can_convert_intype_to_type
477 && (convtype
& CONV_IMPLICIT
) && IS_AGGR_TYPE (intype
)
478 && ! (flags
& LOOKUP_NO_CONVERSION
))
480 /* Look for a user-defined conversion to lvalue that we can use. */
483 = build_type_conversion (reftype
, expr
);
485 if (rval_as_conversion
&& rval_as_conversion
!= error_mark_node
486 && real_lvalue_p (rval_as_conversion
))
488 expr
= rval_as_conversion
;
489 rval_as_conversion
= NULL_TREE
;
491 can_convert_intype_to_type
= 1;
495 if (((convtype
& CONV_STATIC
) && can_convert (intype
, type
))
496 || ((convtype
& CONV_IMPLICIT
) && can_convert_intype_to_type
))
498 if (flags
& LOOKUP_COMPLAIN
)
500 tree ttl
= TREE_TYPE (reftype
);
501 tree ttr
= lvalue_type (expr
);
503 if (! real_lvalue_p (expr
))
504 warn_ref_binding (reftype
, intype
, decl
);
506 if (! (convtype
& CONV_CONST
)
507 && !at_least_as_qualified_p (ttl
, ttr
))
508 pedwarn ("conversion from `%T' to `%T' discards qualifiers",
512 return build_up_reference (reftype
, expr
, flags
, decl
);
514 else if ((convtype
& CONV_REINTERPRET
) && lvalue_p (expr
))
516 /* When casting an lvalue to a reference type, just convert into
517 a pointer to the new type and deference it. This is allowed
518 by San Diego WP section 5.2.9 paragraph 12, though perhaps it
519 should be done directly (jason). (int &)ri ---> *(int*)&ri */
521 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
523 if (TREE_CODE (intype
) == POINTER_TYPE
524 && (comptypes (TREE_TYPE (intype
), type
,
525 COMPARE_BASE
| COMPARE_DERIVED
)))
526 warning ("casting `%T' to `%T' does not dereference pointer",
529 rval
= build_unary_op (ADDR_EXPR
, expr
, 0);
530 if (rval
!= error_mark_node
)
531 rval
= convert_force (build_pointer_type (TREE_TYPE (reftype
)),
533 if (rval
!= error_mark_node
)
534 rval
= build1 (NOP_EXPR
, reftype
, rval
);
538 rval
= convert_for_initialization (NULL_TREE
, type
, expr
, flags
,
540 if (rval
== NULL_TREE
|| rval
== error_mark_node
)
542 warn_ref_binding (reftype
, intype
, decl
);
543 rval
= build_up_reference (reftype
, rval
, flags
, decl
);
548 /* If we found a way to convert earlier, then use it. */
552 if (flags
& LOOKUP_COMPLAIN
)
553 error ("cannot convert type `%T' to type `%T'", intype
, reftype
);
555 if (flags
& LOOKUP_SPECULATIVELY
)
558 return error_mark_node
;
561 /* We are using a reference VAL for its value. Bash that reference all the
562 way down to its lowest form. */
565 convert_from_reference (tree val
)
567 if (TREE_CODE (TREE_TYPE (val
)) == REFERENCE_TYPE
)
568 return build_indirect_ref (val
, NULL
);
572 /* Implicitly convert the lvalue EXPR to another lvalue of type TOTYPE,
573 preserving cv-qualification. */
576 convert_lvalue (tree totype
, tree expr
)
578 totype
= cp_build_qualified_type (totype
, TYPE_QUALS (TREE_TYPE (expr
)));
579 totype
= build_reference_type (totype
);
580 expr
= convert_to_reference (totype
, expr
, CONV_IMPLICIT
, LOOKUP_NORMAL
,
582 return convert_from_reference (expr
);
585 /* Really perform an lvalue-to-rvalue conversion, including copying an
586 argument of class type into a temporary. */
589 force_rvalue (tree expr
)
591 if (IS_AGGR_TYPE (TREE_TYPE (expr
)) && TREE_CODE (expr
) != TARGET_EXPR
)
592 expr
= ocp_convert (TREE_TYPE (expr
), expr
,
593 CONV_IMPLICIT
|CONV_FORCE_TEMP
, LOOKUP_NORMAL
);
595 expr
= decay_conversion (expr
);
600 /* C++ conversions, preference to static cast conversions. */
603 cp_convert (tree type
, tree expr
)
605 return ocp_convert (type
, expr
, CONV_OLD_CONVERT
, LOOKUP_NORMAL
);
610 FLAGS indicates how we should behave. */
613 ocp_convert (tree type
, tree expr
, int convtype
, int flags
)
615 register tree e
= expr
;
616 register enum tree_code code
= TREE_CODE (type
);
618 if (error_operand_p (e
) || type
== error_mark_node
)
619 return error_mark_node
;
621 complete_type (type
);
622 complete_type (TREE_TYPE (expr
));
624 e
= decl_constant_value (e
);
626 if (IS_AGGR_TYPE (type
) && (convtype
& CONV_FORCE_TEMP
)
627 /* Some internal structures (vtable_entry_type, sigtbl_ptr_type)
628 don't go through finish_struct, so they don't have the synthesized
629 constructors. So don't force a temporary. */
630 && TYPE_HAS_CONSTRUCTOR (type
))
631 /* We need a new temporary; don't take this shortcut. */;
632 else if (TYPE_MAIN_VARIANT (type
) == TYPE_MAIN_VARIANT (TREE_TYPE (e
)))
634 if (same_type_p (type
, TREE_TYPE (e
)))
635 /* The call to fold will not always remove the NOP_EXPR as
636 might be expected, since if one of the types is a typedef;
637 the comparison in fold is just equality of pointers, not a
638 call to comptypes. We don't call fold in this case because
639 that can result in infinite recursion; fold will call
640 convert, which will call ocp_convert, etc. */
642 /* For complex data types, we need to perform componentwise
644 else if (TREE_CODE (type
) == COMPLEX_TYPE
)
645 return fold (convert_to_complex (type
, e
));
646 else if (TREE_CODE (e
) == TARGET_EXPR
)
648 /* Don't build a NOP_EXPR of class type. Instead, change the
649 type of the temporary. Only allow this for cv-qual changes,
651 if (!same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (e
)),
652 TYPE_MAIN_VARIANT (type
)))
654 TREE_TYPE (e
) = TREE_TYPE (TARGET_EXPR_SLOT (e
)) = type
;
657 else if (TREE_ADDRESSABLE (type
))
658 /* We shouldn't be treating objects of ADDRESSABLE type as rvalues. */
661 return fold (build1 (NOP_EXPR
, type
, e
));
664 if (code
== VOID_TYPE
&& (convtype
& CONV_STATIC
))
666 e
= convert_to_void (e
, /*implicit=*/NULL
);
670 if (INTEGRAL_CODE_P (code
))
672 tree intype
= TREE_TYPE (e
);
673 /* enum = enum, enum = int, enum = float, (enum)pointer are all
675 if (TREE_CODE (type
) == ENUMERAL_TYPE
676 && ((ARITHMETIC_TYPE_P (intype
) && ! (convtype
& CONV_STATIC
))
677 || (TREE_CODE (intype
) == POINTER_TYPE
)))
679 pedwarn ("conversion from `%#T' to `%#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 ("`%#T' used where a `%T' was expected", intype
, type
);
692 if (flags
& LOOKUP_SPECULATIVELY
)
694 return error_mark_node
;
696 if (code
== BOOLEAN_TYPE
)
697 return cp_truthvalue_conversion (e
);
699 return fold (convert_to_integer (type
, e
));
701 if (POINTER_TYPE_P (type
) || TYPE_PTR_TO_MEMBER_P (type
))
702 return fold (cp_convert_to_pointer (type
, e
, false));
703 if (code
== VECTOR_TYPE
)
704 return fold (convert_to_vector (type
, e
));
705 if (code
== REAL_TYPE
|| code
== COMPLEX_TYPE
)
707 if (IS_AGGR_TYPE (TREE_TYPE (e
)))
710 rval
= build_type_conversion (type
, e
);
714 if (flags
& LOOKUP_COMPLAIN
)
715 error ("`%#T' used where a floating point value was expected",
718 if (code
== REAL_TYPE
)
719 return fold (convert_to_real (type
, e
));
720 else if (code
== COMPLEX_TYPE
)
721 return fold (convert_to_complex (type
, e
));
724 /* New C++ semantics: since assignment is now based on
725 memberwise copying, if the rhs type is derived from the
726 lhs type, then we may still do a conversion. */
727 if (IS_AGGR_TYPE_CODE (code
))
729 tree dtype
= TREE_TYPE (e
);
730 tree ctor
= NULL_TREE
;
732 dtype
= TYPE_MAIN_VARIANT (dtype
);
734 /* Conversion between aggregate types. New C++ semantics allow
735 objects of derived type to be cast to objects of base type.
736 Old semantics only allowed this between pointers.
738 There may be some ambiguity between using a constructor
739 vs. using a type conversion operator when both apply. */
743 if (abstract_virtuals_error (NULL_TREE
, type
))
744 return error_mark_node
;
746 if ((flags
& LOOKUP_ONLYCONVERTING
)
747 && ! (IS_AGGR_TYPE (dtype
) && DERIVED_FROM_P (type
, dtype
)))
748 /* For copy-initialization, first we create a temp of the proper type
749 with a user-defined conversion sequence, then we direct-initialize
750 the target with the temp (see [dcl.init]). */
751 ctor
= build_user_type_conversion (type
, ctor
, flags
);
753 ctor
= build_special_member_call (NULL_TREE
,
754 complete_ctor_identifier
,
755 build_tree_list (NULL_TREE
, ctor
),
756 TYPE_BINFO (type
), flags
);
758 return build_cplus_new (type
, ctor
);
761 if (flags
& LOOKUP_COMPLAIN
)
762 error ("conversion from `%T' to non-scalar type `%T' requested",
763 TREE_TYPE (expr
), type
);
764 if (flags
& LOOKUP_SPECULATIVELY
)
766 return error_mark_node
;
769 /* When an expression is used in a void context, its value is discarded and
770 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
771 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
772 in a void context. The C++ standard does not define what an `access' to an
773 object is, but there is reason to believe that it is the lvalue to rvalue
774 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
775 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
776 indicates that volatile semantics should be the same between C and C++
777 where ever possible. C leaves it implementation defined as to what
778 constitutes an access to a volatile. So, we interpret `*vp' as a read of
779 the volatile object `vp' points to, unless that is an incomplete type. For
780 volatile references we do not do this interpretation, because that would
781 make it impossible to ignore the reference return value from functions. We
782 issue warnings in the confusing cases.
784 IMPLICIT is tells us the context of an implicit void conversion. */
787 convert_to_void (tree expr
, const char *implicit
)
789 if (expr
== error_mark_node
790 || TREE_TYPE (expr
) == error_mark_node
)
791 return error_mark_node
;
792 if (!TREE_TYPE (expr
))
794 if (VOID_TYPE_P (TREE_TYPE (expr
)))
796 switch (TREE_CODE (expr
))
800 /* The two parts of a cond expr might be separate lvalues. */
801 tree op1
= TREE_OPERAND (expr
,1);
802 tree op2
= TREE_OPERAND (expr
,2);
803 tree new_op1
= convert_to_void
804 (op1
, (implicit
&& !TREE_SIDE_EFFECTS (op2
)
805 ? "second operand of conditional" : NULL
));
806 tree new_op2
= convert_to_void
807 (op2
, (implicit
&& !TREE_SIDE_EFFECTS (op1
)
808 ? "third operand of conditional" : NULL
));
810 expr
= build (COND_EXPR
, TREE_TYPE (new_op1
),
811 TREE_OPERAND (expr
, 0), new_op1
, new_op2
);
817 /* The second part of a compound expr contains the value. */
818 tree op1
= TREE_OPERAND (expr
,1);
819 tree new_op1
= convert_to_void
820 (op1
, implicit
? "right-hand operand of comma" : NULL
);
824 tree t
= build (COMPOUND_EXPR
, TREE_TYPE (new_op1
),
825 TREE_OPERAND (expr
, 0), new_op1
);
832 case NON_LVALUE_EXPR
:
834 /* These have already decayed to rvalue. */
837 case CALL_EXPR
: /* we have a special meaning for volatile void fn() */
842 tree type
= TREE_TYPE (expr
);
843 int is_reference
= TREE_CODE (TREE_TYPE (TREE_OPERAND (expr
, 0)))
845 int is_volatile
= TYPE_VOLATILE (type
);
846 int is_complete
= COMPLETE_TYPE_P (complete_type (type
));
848 if (is_volatile
&& !is_complete
)
849 warning ("object of incomplete type `%T' will not be accessed in %s",
850 type
, implicit
? implicit
: "void context");
851 else if (is_reference
&& is_volatile
)
852 warning ("object of type `%T' will not be accessed in %s",
853 TREE_TYPE (TREE_OPERAND (expr
, 0)),
854 implicit
? implicit
: "void context");
855 if (is_reference
|| !is_volatile
|| !is_complete
)
856 expr
= TREE_OPERAND (expr
, 0);
863 /* External variables might be incomplete. */
864 tree type
= TREE_TYPE (expr
);
865 int is_complete
= COMPLETE_TYPE_P (complete_type (type
));
867 if (TYPE_VOLATILE (type
) && !is_complete
)
868 warning ("object `%E' of incomplete type `%T' will not be accessed in %s",
869 expr
, type
, implicit
? implicit
: "void context");
878 if (TREE_CODE (probe
) == ADDR_EXPR
)
879 probe
= TREE_OPERAND (expr
, 0);
880 if (type_unknown_p (probe
))
882 /* [over.over] enumerates the places where we can take the address
883 of an overloaded function, and this is not one of them. */
884 pedwarn ("%s cannot resolve address of overloaded function",
885 implicit
? implicit
: "void cast");
887 else if (implicit
&& probe
== expr
&& is_overloaded_fn (probe
))
888 /* Only warn when there is no &. */
889 warning ("%s is a reference, not call, to function `%E'",
893 if (expr
!= error_mark_node
&& !VOID_TYPE_P (TREE_TYPE (expr
)))
895 if (implicit
&& !TREE_SIDE_EFFECTS (expr
) && warn_unused_value
)
896 warning ("%s has no effect", implicit
);
897 expr
= build1 (CONVERT_EXPR
, void_type_node
, expr
);
902 /* Create an expression whose value is that of EXPR,
903 converted to type TYPE. The TREE_TYPE of the value
904 is always TYPE. This function implements all reasonable
905 conversions; callers should filter out those that are
906 not permitted by the language being compiled.
908 Most of this routine is from build_reinterpret_cast.
910 The backend cannot call cp_convert (what was convert) because
911 conversions to/from basetypes may involve memory references
912 (vbases) and adding or subtracting small values (multiple
913 inheritance), but it calls convert from the constant folding code
914 on subtrees of already built trees after it has ripped them apart.
916 Also, if we ever support range variables, we'll probably also have to
917 do a little bit more work. */
920 convert (tree type
, tree expr
)
924 if (type
== error_mark_node
|| expr
== error_mark_node
)
925 return error_mark_node
;
927 intype
= TREE_TYPE (expr
);
929 if (POINTER_TYPE_P (type
) && POINTER_TYPE_P (intype
))
931 expr
= decl_constant_value (expr
);
932 return fold (build1 (NOP_EXPR
, type
, expr
));
935 return ocp_convert (type
, expr
, CONV_OLD_CONVERT
,
936 LOOKUP_NORMAL
|LOOKUP_NO_CONVERSION
);
939 /* Like cp_convert, except permit conversions to take place which
940 are not normally allowed due to access restrictions
941 (such as conversion from sub-type to private super-type). */
944 convert_force (tree type
, tree expr
, int convtype
)
946 register tree e
= expr
;
947 register enum tree_code code
= TREE_CODE (type
);
949 if (code
== REFERENCE_TYPE
)
950 return fold (convert_to_reference (type
, e
, CONV_C_CAST
, LOOKUP_COMPLAIN
,
952 else if (TREE_CODE (TREE_TYPE (e
)) == REFERENCE_TYPE
)
953 e
= convert_from_reference (e
);
955 if (code
== POINTER_TYPE
)
956 return fold (convert_to_pointer_force (type
, e
));
958 /* From typeck.c convert_for_assignment */
959 if (((TREE_CODE (TREE_TYPE (e
)) == POINTER_TYPE
&& TREE_CODE (e
) == ADDR_EXPR
960 && TREE_CODE (TREE_TYPE (e
)) == POINTER_TYPE
961 && TREE_CODE (TREE_TYPE (TREE_TYPE (e
))) == METHOD_TYPE
)
963 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e
)))
964 && TYPE_PTRMEMFUNC_P (type
))
966 /* compatible pointer to member functions. */
967 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), e
, 1);
970 return ocp_convert (type
, e
, CONV_C_CAST
|convtype
, LOOKUP_NORMAL
);
973 /* Convert an aggregate EXPR to type XTYPE. If a conversion
974 exists, return the attempted conversion. This may
975 return ERROR_MARK_NODE if the conversion is not
976 allowed (references private members, etc).
977 If no conversion exists, NULL_TREE is returned.
979 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
980 object parameter, or by the second standard conversion sequence if
981 that doesn't do it. This will probably wait for an overloading rewrite.
985 build_type_conversion (tree xtype
, tree expr
)
987 /* C++: check to see if we can convert this aggregate type
988 into the required type. */
989 return build_user_type_conversion (xtype
, expr
, LOOKUP_NORMAL
);
992 /* Convert the given EXPR to one of a group of types suitable for use in an
993 expression. DESIRES is a combination of various WANT_* flags (q.v.)
994 which indicates which types are suitable. If COMPLAIN is true, complain
995 about ambiguity; otherwise, the caller will deal with it. */
998 build_expr_type_conversion (int desires
, tree expr
, bool complain
)
1000 tree basetype
= TREE_TYPE (expr
);
1001 tree conv
= NULL_TREE
;
1002 tree winner
= NULL_TREE
;
1004 if (expr
== null_node
1005 && (desires
& WANT_INT
)
1006 && !(desires
& WANT_NULL
))
1007 warning ("converting NULL to non-pointer type");
1009 expr
= convert_from_reference (expr
);
1010 basetype
= TREE_TYPE (expr
);
1012 if (basetype
== error_mark_node
)
1013 return error_mark_node
;
1015 if (! IS_AGGR_TYPE (basetype
))
1016 switch (TREE_CODE (basetype
))
1019 if ((desires
& WANT_NULL
) && null_ptr_cst_p (expr
))
1021 /* else fall through... */
1024 return (desires
& WANT_INT
) ? expr
: NULL_TREE
;
1026 return (desires
& WANT_ENUM
) ? expr
: NULL_TREE
;
1028 return (desires
& WANT_FLOAT
) ? expr
: NULL_TREE
;
1030 return (desires
& WANT_POINTER
) ? expr
: NULL_TREE
;
1034 return (desires
& WANT_POINTER
) ? decay_conversion (expr
)
1040 /* The code for conversions from class type is currently only used for
1041 delete expressions. Other expressions are handled by build_new_op. */
1043 if (! TYPE_HAS_CONVERSION (basetype
))
1046 for (conv
= lookup_conversions (basetype
); conv
; conv
= TREE_CHAIN (conv
))
1050 tree cand
= TREE_VALUE (conv
);
1052 if (winner
&& winner
== cand
)
1055 candidate
= non_reference (TREE_TYPE (TREE_TYPE (cand
)));
1057 switch (TREE_CODE (candidate
))
1061 win
= (desires
& WANT_INT
); break;
1063 win
= (desires
& WANT_ENUM
); break;
1065 win
= (desires
& WANT_FLOAT
); break;
1067 win
= (desires
& WANT_POINTER
); break;
1079 error ("ambiguous default type conversion from `%T'",
1081 error (" candidate conversions include `%D' and `%D'",
1084 return error_mark_node
;
1093 tree type
= non_reference (TREE_TYPE (TREE_TYPE (winner
)));
1094 return build_user_type_conversion (type
, expr
, LOOKUP_NORMAL
);
1100 /* Implements integral promotion (4.1) and float->double promotion. */
1103 type_promotes_to (tree type
)
1105 if (type
== error_mark_node
)
1106 return error_mark_node
;
1108 type
= TYPE_MAIN_VARIANT (type
);
1110 /* bool always promotes to int (not unsigned), even if it's the same
1112 if (type
== boolean_type_node
)
1113 type
= integer_type_node
;
1115 /* Normally convert enums to int, but convert wide enums to something
1117 else if (TREE_CODE (type
) == ENUMERAL_TYPE
1118 || type
== wchar_type_node
)
1120 int precision
= MAX (TYPE_PRECISION (type
),
1121 TYPE_PRECISION (integer_type_node
));
1122 tree totype
= c_common_type_for_size (precision
, 0);
1123 if (TREE_UNSIGNED (type
)
1124 && ! int_fits_type_p (TYPE_MAX_VALUE (type
), totype
))
1125 type
= c_common_type_for_size (precision
, 1);
1129 else if (c_promoting_integer_type_p (type
))
1131 /* Retain unsignedness if really not getting bigger. */
1132 if (TREE_UNSIGNED (type
)
1133 && TYPE_PRECISION (type
) == TYPE_PRECISION (integer_type_node
))
1134 type
= unsigned_type_node
;
1136 type
= integer_type_node
;
1138 else if (type
== float_type_node
)
1139 type
= double_type_node
;
1144 /* The routines below this point are carefully written to conform to
1145 the standard. They use the same terminology, and follow the rules
1146 closely. Although they are used only in pt.c at the moment, they
1147 should presumably be used everywhere in the future. */
1149 /* Attempt to perform qualification conversions on EXPR to convert it
1150 to TYPE. Return the resulting expression, or error_mark_node if
1151 the conversion was impossible. */
1154 perform_qualification_conversions (tree type
, tree expr
)
1158 expr_type
= TREE_TYPE (expr
);
1160 if (TYPE_PTR_P (type
) && TYPE_PTR_P (expr_type
)
1161 && comp_ptr_ttypes (TREE_TYPE (type
), TREE_TYPE (expr_type
)))
1162 return build_nop (type
, expr
);
1163 else if (TYPE_PTR_TO_MEMBER_P (type
)
1164 && TYPE_PTR_TO_MEMBER_P (expr_type
)
1165 && same_type_p (TYPE_PTRMEM_CLASS_TYPE (type
),
1166 TYPE_PTRMEM_CLASS_TYPE (expr_type
))
1167 && comp_ptr_ttypes (TYPE_PTRMEM_POINTED_TO_TYPE (type
),
1168 TYPE_PTRMEM_POINTED_TO_TYPE (expr_type
)))
1169 return build_nop (type
, expr
);
1171 return error_mark_node
;