1 /* Language-level data type conversion for GNU C++.
2 Copyright (C) 1987-1988, 1992-1999 Free Software Foundation, Inc.
3 Hacked by Michael Tiemann (tiemann@cygnus.com)
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
23 /* This file contains the functions for converting C expressions
24 to different data types. The only entry point is `convert'.
25 Every language front end must have a `convert' function
26 but what kind of conversions it does will depend on the language. */
37 static tree cp_convert_to_pointer
PROTO((tree
, tree
));
38 static tree convert_to_pointer_force
PROTO((tree
, tree
));
39 static tree build_up_reference
PROTO((tree
, tree
, int));
41 /* Change of width--truncation and extension of integers or reals--
42 is represented with NOP_EXPR. Proper functioning of many things
43 assumes that no other conversions can be NOP_EXPRs.
45 Conversion between integer and pointer is represented with CONVERT_EXPR.
46 Converting integer to real uses FLOAT_EXPR
47 and real to integer uses FIX_TRUNC_EXPR.
49 Here is a list of all the functions that assume that widening and
50 narrowing is always done with a NOP_EXPR:
51 In convert.c, convert_to_integer.
52 In c-typeck.c, build_binary_op_nodefault (boolean ops),
53 and truthvalue_conversion.
54 In expr.c: expand_expr, for operands of a MULT_EXPR.
55 In fold-const.c: fold.
56 In tree.c: get_narrower and get_unwidened.
58 C++: in multiple-inheritance, converting between pointers may involve
59 adjusting them by a delta stored within the class definition. */
61 /* Subroutines of `convert'. */
63 /* if converting pointer to pointer
64 if dealing with classes, check for derived->base or vice versa
65 else if dealing with method pointers, delegate
67 else if converting class, pass off to build_type_conversion
68 else try C-style pointer conversion */
71 cp_convert_to_pointer (type
, expr
)
74 register tree intype
= TREE_TYPE (expr
);
75 register enum tree_code form
;
78 if (IS_AGGR_TYPE (intype
))
80 intype
= complete_type (intype
);
81 if (TYPE_SIZE (intype
) == NULL_TREE
)
83 cp_error ("can't convert from incomplete type `%T' to `%T'",
85 return error_mark_node
;
88 rval
= build_type_conversion (type
, expr
, 1);
91 if (rval
== error_mark_node
)
92 cp_error ("conversion of `%E' from `%T' to `%T' is ambiguous",
98 /* Handle anachronistic conversions from (::*)() to cv void* or (*)(). */
99 if (TREE_CODE (type
) == POINTER_TYPE
100 && (TREE_CODE (TREE_TYPE (type
)) == FUNCTION_TYPE
101 || TYPE_MAIN_VARIANT (TREE_TYPE (type
)) == void_type_node
))
103 /* Allow an implicit this pointer for pointer to member
105 if (TYPE_PTRMEMFUNC_P (intype
))
107 tree fntype
= TREE_TYPE (TYPE_PTRMEMFUNC_FN_TYPE (intype
));
108 tree decl
= maybe_dummy_object (TYPE_METHOD_BASETYPE (fntype
), 0);
109 expr
= build (OFFSET_REF
, fntype
, decl
, expr
);
112 if (TREE_CODE (expr
) == OFFSET_REF
113 && TREE_CODE (TREE_TYPE (expr
)) == METHOD_TYPE
)
114 expr
= resolve_offset_ref (expr
);
115 if (TREE_CODE (TREE_TYPE (expr
)) == METHOD_TYPE
)
116 expr
= build_addr_func (expr
);
117 if (TREE_CODE (TREE_TYPE (expr
)) == POINTER_TYPE
)
119 if (TREE_CODE (TREE_TYPE (TREE_TYPE (expr
))) == METHOD_TYPE
)
120 if (pedantic
|| warn_pmf2ptr
)
121 cp_pedwarn ("converting from `%T' to `%T'", TREE_TYPE (expr
),
123 return build1 (NOP_EXPR
, type
, expr
);
125 intype
= TREE_TYPE (expr
);
128 form
= TREE_CODE (intype
);
130 if (POINTER_TYPE_P (intype
))
132 intype
= TYPE_MAIN_VARIANT (intype
);
134 if (TYPE_MAIN_VARIANT (type
) != intype
135 && TREE_CODE (type
) == POINTER_TYPE
136 && TREE_CODE (TREE_TYPE (type
)) == RECORD_TYPE
137 && IS_AGGR_TYPE (TREE_TYPE (type
))
138 && IS_AGGR_TYPE (TREE_TYPE (intype
))
139 && TREE_CODE (TREE_TYPE (intype
)) == RECORD_TYPE
140 /* If EXPR is NULL, then we don't need to do any arithmetic
145 The null pointer value is converted to the null pointer
146 value of the destination type. */
147 && !integer_zerop (expr
))
149 enum tree_code code
= PLUS_EXPR
;
150 tree binfo
= get_binfo (TREE_TYPE (type
), TREE_TYPE (intype
), 1);
151 if (binfo
== error_mark_node
)
152 return error_mark_node
;
153 if (binfo
== NULL_TREE
)
155 binfo
= get_binfo (TREE_TYPE (intype
), TREE_TYPE (type
), 1);
156 if (binfo
== error_mark_node
)
157 return error_mark_node
;
162 if (TYPE_USES_VIRTUAL_BASECLASSES (TREE_TYPE (type
))
163 || TYPE_USES_VIRTUAL_BASECLASSES (TREE_TYPE (intype
))
164 || ! BINFO_OFFSET_ZEROP (binfo
))
166 /* Need to get the path we took. */
169 if (code
== PLUS_EXPR
)
170 get_base_distance (TREE_TYPE (type
), TREE_TYPE (intype
),
173 get_base_distance (TREE_TYPE (intype
), TREE_TYPE (type
),
175 return build_vbase_path (code
, type
, expr
, path
, 0);
180 if (TYPE_PTRMEM_P (type
) && TYPE_PTRMEM_P (intype
))
187 b1
= TYPE_OFFSET_BASETYPE (TREE_TYPE (type
));
188 b2
= TYPE_OFFSET_BASETYPE (TREE_TYPE (intype
));
189 binfo
= get_binfo (b2
, b1
, 1);
191 if (binfo
== NULL_TREE
)
193 binfo
= get_binfo (b1
, b2
, 1);
199 if (binfo
== error_mark_node
)
200 return error_mark_node
;
202 if (binfo_from_vbase (binfo
))
204 cp_error ("conversion to `%T' from pointer to member of virtual base `%T'",
206 return error_mark_node
;
209 if (TREE_CODE (expr
) == PTRMEM_CST
)
210 expr
= cplus_expand_constant (expr
);
212 if (binfo
&& ! TREE_VIA_VIRTUAL (binfo
))
213 expr
= size_binop (code
, expr
, BINFO_OFFSET (binfo
));
215 else if (TYPE_PTRMEMFUNC_P (type
))
217 cp_error ("cannot convert `%E' from type `%T' to type `%T'",
219 return error_mark_node
;
222 rval
= build1 (NOP_EXPR
, type
, expr
);
223 TREE_CONSTANT (rval
) = TREE_CONSTANT (expr
);
226 else if (TYPE_PTRMEMFUNC_P (type
) && TYPE_PTRMEMFUNC_P (intype
))
227 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), expr
, 0);
228 else if (TYPE_PTRMEMFUNC_P (intype
))
230 cp_error ("cannot convert `%E' from type `%T' to type `%T'",
232 return error_mark_node
;
235 my_friendly_assert (form
!= OFFSET_TYPE
, 186);
237 if (integer_zerop (expr
))
239 if (TYPE_PTRMEMFUNC_P (type
))
240 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), expr
, 0);
241 expr
= build_int_2 (0, 0);
242 TREE_TYPE (expr
) = type
;
246 if (INTEGRAL_CODE_P (form
))
248 if (TYPE_PRECISION (intype
) == POINTER_SIZE
)
249 return build1 (CONVERT_EXPR
, type
, expr
);
250 expr
= cp_convert (type_for_size (POINTER_SIZE
, 0), expr
);
251 /* Modes may be different but sizes should be the same. */
252 if (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr
)))
253 != GET_MODE_SIZE (TYPE_MODE (type
)))
254 /* There is supposed to be some integral type
255 that is the same width as a pointer. */
257 return convert_to_pointer (type
, expr
);
260 if (type_unknown_p (expr
))
261 return instantiate_type (type
, expr
, 1);
263 cp_error ("cannot convert `%E' from type `%T' to type `%T'",
265 return error_mark_node
;
268 /* Like convert, except permit conversions to take place which
269 are not normally allowed due to access restrictions
270 (such as conversion from sub-type to private super-type). */
273 convert_to_pointer_force (type
, expr
)
276 register tree intype
= TREE_TYPE (expr
);
277 register enum tree_code form
= TREE_CODE (intype
);
279 if (integer_zerop (expr
))
281 expr
= build_int_2 (0, 0);
282 TREE_TYPE (expr
) = type
;
286 if (form
== POINTER_TYPE
)
288 intype
= TYPE_MAIN_VARIANT (intype
);
290 if (TYPE_MAIN_VARIANT (type
) != intype
291 && TREE_CODE (TREE_TYPE (type
)) == RECORD_TYPE
292 && IS_AGGR_TYPE (TREE_TYPE (type
))
293 && IS_AGGR_TYPE (TREE_TYPE (intype
))
294 && TREE_CODE (TREE_TYPE (intype
)) == RECORD_TYPE
)
296 enum tree_code code
= PLUS_EXPR
;
298 int distance
= get_base_distance (TREE_TYPE (type
),
299 TREE_TYPE (intype
), 0, &path
);
303 cp_error ("type `%T' is ambiguous baseclass of `%s'",
305 TYPE_NAME_STRING (TREE_TYPE (intype
)));
306 return error_mark_node
;
310 distance
= get_base_distance (TREE_TYPE (intype
),
311 TREE_TYPE (type
), 0, &path
);
315 /* Doesn't need any special help from us. */
316 return build1 (NOP_EXPR
, type
, expr
);
320 return build_vbase_path (code
, type
, expr
, path
, 0);
324 return cp_convert_to_pointer (type
, expr
);
327 /* We are passing something to a function which requires a reference.
328 The type we are interested in is in TYPE. The initial
329 value we have to begin with is in ARG.
331 FLAGS controls how we manage access checking.
332 DIRECT_BIND in FLAGS controls how any temporaries are generated. */
335 build_up_reference (type
, arg
, flags
)
340 tree argtype
= TREE_TYPE (arg
);
341 tree target_type
= TREE_TYPE (type
);
342 tree stmt_expr
= NULL_TREE
;
344 my_friendly_assert (TREE_CODE (type
) == REFERENCE_TYPE
, 187);
346 if ((flags
& DIRECT_BIND
) && ! real_lvalue_p (arg
))
350 /* Create a new temporary variable. */
352 if (toplevel_bindings_p ())
353 arg
= get_temp_name (argtype
, 1);
356 arg
= pushdecl (build_decl (VAR_DECL
, NULL_TREE
, argtype
));
357 DECL_ARTIFICIAL (arg
) = 1;
358 /* Generate code to initialize it. We wrap it in a
359 statement-expression so that when we are building a
360 statement-tree we will have a representation of this
362 begin_init_stmts (&stmt_expr
, &compound_stmt
);
365 /* Process the initializer for the declaration. */
366 DECL_INITIAL (arg
) = targ
;
367 cp_finish_decl (arg
, targ
, NULL_TREE
, 0,
368 LOOKUP_ONLYCONVERTING
|DIRECT_BIND
);
370 /* And wrap up the statement-expression, if necessary. */
371 if (!toplevel_bindings_p ())
373 if (building_stmt_tree ())
375 stmt_expr
= finish_init_stmts (stmt_expr
, compound_stmt
);
378 else if (!(flags
& DIRECT_BIND
) && ! lvalue_p (arg
))
380 tree slot
= build_decl (VAR_DECL
, NULL_TREE
, argtype
);
381 DECL_ARTIFICIAL (slot
) = 1;
382 arg
= build (TARGET_EXPR
, argtype
, slot
, arg
, NULL_TREE
, NULL_TREE
);
383 TREE_SIDE_EFFECTS (arg
) = 1;
386 /* If we had a way to wrap this up, and say, if we ever needed it's
387 address, transform all occurrences of the register, into a memory
388 reference we could win better. */
389 rval
= build_unary_op (ADDR_EXPR
, arg
, 1);
390 if (rval
== error_mark_node
)
391 return error_mark_node
;
393 if ((flags
& LOOKUP_PROTECT
)
394 && TYPE_MAIN_VARIANT (argtype
) != TYPE_MAIN_VARIANT (target_type
)
395 && IS_AGGR_TYPE (argtype
)
396 && IS_AGGR_TYPE (target_type
))
398 /* We go through get_binfo for the access control. */
399 tree binfo
= get_binfo (target_type
, argtype
, 1);
400 if (binfo
== error_mark_node
)
401 return error_mark_node
;
402 if (binfo
== NULL_TREE
)
403 return error_not_base_type (target_type
, argtype
);
404 rval
= convert_pointer_to_real (binfo
, rval
);
408 = convert_to_pointer_force (build_pointer_type (target_type
), rval
);
409 rval
= build1 (NOP_EXPR
, type
, rval
);
410 TREE_CONSTANT (rval
) = TREE_CONSTANT (TREE_OPERAND (rval
, 0));
412 /* If we created and initialized a new temporary variable, add the
413 representation of that initialization to the RVAL. */
415 rval
= build (COMPOUND_EXPR
, TREE_TYPE (rval
), stmt_expr
, rval
);
417 /* And return the result. */
421 /* For C++: Only need to do one-level references, but cannot
422 get tripped up on signed/unsigned differences.
424 DECL is either NULL_TREE or the _DECL node for a reference that is being
425 initialized. It can be error_mark_node if we don't know the _DECL but
426 we know it's an initialization. */
429 convert_to_reference (reftype
, expr
, convtype
, flags
, decl
)
434 register tree type
= TYPE_MAIN_VARIANT (TREE_TYPE (reftype
));
435 register tree intype
= TREE_TYPE (expr
);
436 tree rval
= NULL_TREE
;
437 tree rval_as_conversion
= NULL_TREE
;
440 if (TREE_CODE (type
) == FUNCTION_TYPE
&& intype
== unknown_type_node
)
442 expr
= instantiate_type (type
, expr
,
443 (flags
& LOOKUP_COMPLAIN
) != 0);
444 if (expr
== error_mark_node
)
445 return error_mark_node
;
447 intype
= TREE_TYPE (expr
);
450 if (TREE_CODE (intype
) == REFERENCE_TYPE
)
451 my_friendly_abort (364);
453 intype
= TYPE_MAIN_VARIANT (intype
);
455 i
= comp_target_types (type
, intype
, 0);
457 if (i
<= 0 && (convtype
& CONV_IMPLICIT
) && IS_AGGR_TYPE (intype
)
458 && ! (flags
& LOOKUP_NO_CONVERSION
))
460 /* Look for a user-defined conversion to lvalue that we can use. */
463 = build_type_conversion (reftype
, expr
, 1);
465 if (rval_as_conversion
&& rval_as_conversion
!= error_mark_node
466 && real_lvalue_p (rval_as_conversion
))
468 expr
= rval_as_conversion
;
469 rval_as_conversion
= NULL_TREE
;
475 if (((convtype
& CONV_STATIC
) && i
== -1)
476 || ((convtype
& CONV_IMPLICIT
) && i
== 1))
478 if (flags
& LOOKUP_COMPLAIN
)
480 tree ttl
= TREE_TYPE (reftype
);
481 tree ttr
= lvalue_type (expr
);
483 /* [dcl.init.ref] says that if an rvalue is used to
484 initialize a reference, then the reference must be to a
485 non-volatile const type. */
486 if (! real_lvalue_p (expr
)
487 && !CP_TYPE_CONST_NON_VOLATILE_P (ttl
))
491 if (CP_TYPE_VOLATILE_P (ttl
) && decl
)
492 msg
= "initialization of volatile reference type `%#T'";
493 else if (CP_TYPE_VOLATILE_P (ttl
))
494 msg
= "conversion to volatile reference type `%#T'";
496 msg
= "initialization of non-const reference type `%#T'";
498 msg
= "conversion to non-const reference type `%#T'";
500 cp_pedwarn (msg
, reftype
);
501 cp_pedwarn ("from rvalue of type `%T'", intype
);
503 else if (! (convtype
& CONV_CONST
)
504 && !at_least_as_qualified_p (ttl
, ttr
))
505 cp_pedwarn ("conversion from `%T' to `%T' discards qualifiers",
509 return build_up_reference (reftype
, expr
, flags
);
511 else if ((convtype
& CONV_REINTERPRET
) && lvalue_p (expr
))
513 /* When casting an lvalue to a reference type, just convert into
514 a pointer to the new type and deference it. This is allowed
515 by San Diego WP section 5.2.9 paragraph 12, though perhaps it
516 should be done directly (jason). (int &)ri ---> *(int*)&ri */
518 /* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
520 if (TREE_CODE (intype
) == POINTER_TYPE
521 && (comptypes (TREE_TYPE (intype
), type
,
522 COMPARE_BASE
| COMPARE_RELAXED
)))
523 cp_warning ("casting `%T' to `%T' does not dereference pointer",
526 rval
= build_unary_op (ADDR_EXPR
, expr
, 0);
527 if (rval
!= error_mark_node
)
528 rval
= convert_force (build_pointer_type (TREE_TYPE (reftype
)),
530 if (rval
!= error_mark_node
)
531 rval
= build1 (NOP_EXPR
, reftype
, rval
);
535 rval
= convert_for_initialization (NULL_TREE
, type
, expr
, flags
,
537 if (rval
== NULL_TREE
|| rval
== error_mark_node
)
539 rval
= build_up_reference (reftype
, rval
, flags
);
541 if (rval
&& ! CP_TYPE_CONST_P (TREE_TYPE (reftype
)))
542 cp_pedwarn ("initializing non-const `%T' with `%T' will use a temporary",
548 /* If we found a way to convert earlier, then use it. */
552 my_friendly_assert (TREE_CODE (intype
) != OFFSET_TYPE
, 189);
554 if (flags
& LOOKUP_COMPLAIN
)
555 cp_error ("cannot convert type `%T' to type `%T'", intype
, reftype
);
557 if (flags
& LOOKUP_SPECULATIVELY
)
560 return error_mark_node
;
563 /* We are using a reference VAL for its value. Bash that reference all the
564 way down to its lowest form. */
567 convert_from_reference (val
)
570 tree type
= TREE_TYPE (val
);
572 if (TREE_CODE (type
) == OFFSET_TYPE
)
573 type
= TREE_TYPE (type
);
574 if (TREE_CODE (type
) == REFERENCE_TYPE
)
575 return build_indirect_ref (val
, NULL_PTR
);
579 /* Call this when we know (for any reason) that expr is not, in fact,
580 zero. This routine is like convert_pointer_to, but it pays
581 attention to which specific instance of what type we want to
582 convert to. This routine should eventually become
583 convert_to_pointer after all references to convert_to_pointer
587 convert_pointer_to_real (binfo
, expr
)
590 register tree intype
= TREE_TYPE (expr
);
594 if (intype
== error_mark_node
)
595 return error_mark_node
;
597 if (TREE_CODE (binfo
) == TREE_VEC
)
598 type
= BINFO_TYPE (binfo
);
599 else if (IS_AGGR_TYPE (binfo
))
609 ptr_type
= cp_build_qualified_type (type
,
610 CP_TYPE_QUALS (TREE_TYPE (intype
)));
611 ptr_type
= build_pointer_type (ptr_type
);
612 if (same_type_p (ptr_type
, TYPE_MAIN_VARIANT (intype
)))
615 my_friendly_assert (!integer_zerop (expr
), 191);
617 intype
= TYPE_MAIN_VARIANT (TREE_TYPE (intype
));
618 if (TREE_CODE (type
) == RECORD_TYPE
619 && TREE_CODE (intype
) == RECORD_TYPE
624 = get_base_distance (binfo
, intype
, 0, &path
);
626 /* This function shouldn't be called with unqualified arguments
627 but if it is, give them an error message that they can read. */
630 cp_error ("cannot convert a pointer of type `%T' to a pointer of type `%T'",
634 cp_error ("because `%T' is an ambiguous base class", type
);
635 return error_mark_node
;
638 return build_vbase_path (PLUS_EXPR
, ptr_type
, expr
, path
, 1);
640 rval
= build1 (NOP_EXPR
, ptr_type
,
641 TREE_CODE (expr
) == NOP_EXPR
? TREE_OPERAND (expr
, 0) : expr
);
642 TREE_CONSTANT (rval
) = TREE_CONSTANT (expr
);
646 /* Call this when we know (for any reason) that expr is
647 not, in fact, zero. This routine gets a type out of the first
648 argument and uses it to search for the type to convert to. If there
649 is more than one instance of that type in the expr, the conversion is
650 ambiguous. This routine should eventually go away, and all
651 callers should use convert_to_pointer_real. */
654 convert_pointer_to (binfo
, expr
)
659 if (TREE_CODE (binfo
) == TREE_VEC
)
660 type
= BINFO_TYPE (binfo
);
661 else if (IS_AGGR_TYPE (binfo
))
665 return convert_pointer_to_real (type
, expr
);
668 /* C++ conversions, preference to static cast conversions. */
671 cp_convert (type
, expr
)
674 return ocp_convert (type
, expr
, CONV_OLD_CONVERT
, LOOKUP_NORMAL
);
679 FLAGS indicates how we should behave. */
682 ocp_convert (type
, expr
, convtype
, flags
)
686 register tree e
= expr
;
687 register enum tree_code code
= TREE_CODE (type
);
689 if (e
== error_mark_node
690 || TREE_TYPE (e
) == error_mark_node
)
691 return error_mark_node
;
693 if (TREE_READONLY_DECL_P (e
))
694 e
= decl_constant_value (e
);
696 if (IS_AGGR_TYPE (type
) && (convtype
& CONV_FORCE_TEMP
)
697 /* Some internal structures (vtable_entry_type, sigtbl_ptr_type)
698 don't go through finish_struct, so they don't have the synthesized
699 constructors. So don't force a temporary. */
700 && TYPE_HAS_CONSTRUCTOR (type
))
701 /* We need a new temporary; don't take this shortcut. */;
702 else if (TYPE_MAIN_VARIANT (type
) == TYPE_MAIN_VARIANT (TREE_TYPE (e
)))
704 if (same_type_p (type
, TREE_TYPE (e
)))
705 /* The call to fold will not always remove the NOP_EXPR as
706 might be expected, since if one of the types is a typedef;
707 the comparsion in fold is just equality of pointers, not a
708 call to comptypes. We don't call fold in this case because
709 that can result in infinite recursion; fold will call
710 convert, which will call ocp_convert, etc. */
713 return fold (build1 (NOP_EXPR
, type
, e
));
716 if (code
== VOID_TYPE
&& (convtype
& CONV_STATIC
))
718 e
= convert_to_void (e
, /*implicit=*/NULL
);
723 /* This is incorrect. A truncation can't be stripped this way.
724 Extensions will be stripped by the use of get_unwidened. */
725 if (TREE_CODE (e
) == NOP_EXPR
)
726 return cp_convert (type
, TREE_OPERAND (e
, 0));
729 /* Just convert to the type of the member. */
730 if (code
== OFFSET_TYPE
)
732 type
= TREE_TYPE (type
);
733 code
= TREE_CODE (type
);
737 if (code
== REFERENCE_TYPE
)
738 return fold (convert_to_reference (type
, e
, convtype
, flags
, NULL_TREE
));
739 else if (TREE_CODE (TREE_TYPE (e
)) == REFERENCE_TYPE
)
740 e
= convert_from_reference (e
);
743 if (TREE_CODE (e
) == OFFSET_REF
)
744 e
= resolve_offset_ref (e
);
746 if (INTEGRAL_CODE_P (code
))
748 tree intype
= TREE_TYPE (e
);
749 /* enum = enum, enum = int, enum = float, (enum)pointer are all
751 if (TREE_CODE (type
) == ENUMERAL_TYPE
752 && ((ARITHMETIC_TYPE_P (intype
) && ! (convtype
& CONV_STATIC
))
753 || (TREE_CODE (intype
) == POINTER_TYPE
)))
755 cp_pedwarn ("conversion from `%#T' to `%#T'", intype
, type
);
757 if (flag_pedantic_errors
)
758 return error_mark_node
;
760 if (IS_AGGR_TYPE (intype
))
763 rval
= build_type_conversion (type
, e
, 1);
766 if (flags
& LOOKUP_COMPLAIN
)
767 cp_error ("`%#T' used where a `%T' was expected", intype
, type
);
768 if (flags
& LOOKUP_SPECULATIVELY
)
770 return error_mark_node
;
772 if (code
== BOOLEAN_TYPE
)
774 /* Common Ada/Pascal programmer's mistake. We always warn
775 about this since it is so bad. */
776 if (TREE_CODE (expr
) == FUNCTION_DECL
)
777 cp_warning ("the address of `%D', will always be `true'", expr
);
778 return truthvalue_conversion (e
);
780 return fold (convert_to_integer (type
, e
));
782 if (code
== POINTER_TYPE
|| code
== REFERENCE_TYPE
783 || TYPE_PTRMEMFUNC_P (type
))
784 return fold (cp_convert_to_pointer (type
, e
));
785 if (code
== REAL_TYPE
|| code
== COMPLEX_TYPE
)
787 if (IS_AGGR_TYPE (TREE_TYPE (e
)))
790 rval
= build_type_conversion (type
, e
, 1);
794 if (flags
& LOOKUP_COMPLAIN
)
795 cp_error ("`%#T' used where a floating point value was expected",
798 if (code
== REAL_TYPE
)
799 return fold (convert_to_real (type
, e
));
800 else if (code
== COMPLEX_TYPE
)
801 return fold (convert_to_complex (type
, e
));
804 /* New C++ semantics: since assignment is now based on
805 memberwise copying, if the rhs type is derived from the
806 lhs type, then we may still do a conversion. */
807 if (IS_AGGR_TYPE_CODE (code
))
809 tree dtype
= TREE_TYPE (e
);
810 tree ctor
= NULL_TREE
;
812 dtype
= TYPE_MAIN_VARIANT (dtype
);
814 /* Conversion between aggregate types. New C++ semantics allow
815 objects of derived type to be cast to objects of base type.
816 Old semantics only allowed this between pointers.
818 There may be some ambiguity between using a constructor
819 vs. using a type conversion operator when both apply. */
823 if (abstract_virtuals_error (NULL_TREE
, type
))
824 return error_mark_node
;
826 if ((flags
& LOOKUP_ONLYCONVERTING
)
827 && ! (IS_AGGR_TYPE (dtype
) && DERIVED_FROM_P (type
, dtype
)))
828 /* For copy-initialization, first we create a temp of the proper type
829 with a user-defined conversion sequence, then we direct-initialize
830 the target with the temp (see [dcl.init]). */
831 ctor
= build_user_type_conversion (type
, ctor
, flags
);
833 ctor
= build_method_call (NULL_TREE
, ctor_identifier
,
834 build_expr_list (NULL_TREE
, ctor
),
835 TYPE_BINFO (type
), flags
);
837 return build_cplus_new (type
, ctor
);
840 /* If TYPE or TREE_TYPE (E) is not on the permanent_obstack,
841 then it won't be hashed and hence compare as not equal,
843 if (code
== ARRAY_TYPE
844 && TREE_TYPE (TREE_TYPE (e
)) == TREE_TYPE (type
)
845 && index_type_equal (TYPE_DOMAIN (TREE_TYPE (e
)), TYPE_DOMAIN (type
)))
848 if (flags
& LOOKUP_COMPLAIN
)
849 cp_error ("conversion from `%T' to non-scalar type `%T' requested",
850 TREE_TYPE (expr
), type
);
851 if (flags
& LOOKUP_SPECULATIVELY
)
853 return error_mark_node
;
856 /* When an expression is used in a void context, its value is discarded and
857 no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
858 stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
859 in a void context. The C++ standard does not define what an `access' to an
860 object is, but there is reason to beleive that it is the lvalue to rvalue
861 conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
862 accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
863 indicates that volatile semantics should be the same between C and C++
864 where ever possible. C leaves it implementation defined as to what
865 constitutes an access to a volatile. So, we interpret `*vp' as a read of
866 the volatile object `vp' points to, unless that is an incomplete type. For
867 volatile references we do not do this interpretation, because that would
868 make it impossible to ignore the reference return value from functions. We
869 issue warnings in the confusing cases.
871 IMPLICIT is tells us the context of an implicit void conversion. */
874 convert_to_void (expr
, implicit
)
876 const char *implicit
;
878 if (expr
== error_mark_node
)
880 if (!TREE_TYPE (expr
))
882 if (same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (expr
)), void_type_node
))
884 switch (TREE_CODE (expr
))
888 /* The two parts of a cond expr might be separate lvalues. */
889 tree op1
= TREE_OPERAND (expr
,1);
890 tree op2
= TREE_OPERAND (expr
,2);
891 tree new_op1
= convert_to_void (op1
, implicit
);
892 tree new_op2
= convert_to_void (op2
, implicit
);
894 if (new_op1
!= op1
|| new_op2
!= op2
)
895 expr
= build (COND_EXPR
,
896 implicit
? TREE_TYPE (expr
) : void_type_node
,
897 TREE_OPERAND (expr
, 0), new_op1
, new_op2
);
903 /* The second part of a compound expr contains the value. */
904 tree op1
= TREE_OPERAND (expr
,1);
905 tree new_op1
= convert_to_void (op1
, implicit
);
908 expr
= build (COMPOUND_EXPR
, TREE_TYPE (new_op1
),
909 TREE_OPERAND (expr
, 0), new_op1
);
913 case NON_LVALUE_EXPR
:
915 /* These have already decayed to rvalue. */
918 case CALL_EXPR
: /* we have a special meaning for volatile void fn() */
923 tree type
= TREE_TYPE (expr
);
924 int is_reference
= TREE_CODE (TREE_TYPE (TREE_OPERAND (expr
, 0)))
926 int is_volatile
= TYPE_VOLATILE (type
);
927 int is_complete
= TYPE_SIZE (complete_type (type
)) != NULL_TREE
;
929 if (is_volatile
&& !is_complete
)
930 cp_warning ("object of incomplete type `%T' will not be accessed in %s",
931 type
, implicit
? implicit
: "void context");
932 else if (is_reference
&& is_volatile
)
933 cp_warning ("object of type `%T' will not be accessed in %s",
934 TREE_TYPE (TREE_OPERAND (expr
, 0)),
935 implicit
? implicit
: "void context");
936 if (is_reference
|| !is_volatile
|| !is_complete
)
937 expr
= TREE_OPERAND (expr
, 0);
944 /* External variables might be incomplete. */
945 tree type
= TREE_TYPE (expr
);
946 int is_complete
= TYPE_SIZE (complete_type (type
)) != NULL_TREE
;
948 if (TYPE_VOLATILE (type
) && !is_complete
)
949 cp_warning ("object `%E' of incomplete type `%T' will not be accessed in %s",
950 expr
, type
, implicit
? implicit
: "void context");
959 if (TREE_CODE (probe
) == ADDR_EXPR
)
960 probe
= TREE_OPERAND (expr
, 0);
961 if (!is_overloaded_fn (probe
))
963 else if (really_overloaded_fn (probe
))
965 /* [over.over] enumerates the places where we can take the address
966 of an overloaded function, and this is not one of them. */
967 cp_pedwarn ("%s has no context for overloaded function name `%E'",
968 implicit
? implicit
: "void cast", expr
);
970 else if (implicit
&& probe
== expr
)
971 /* Only warn when there is no &. */
972 cp_warning ("%s is a reference, not call, to function `%E'",
976 if (expr
!= error_mark_node
977 && !same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (expr
)), void_type_node
))
979 /* FIXME: This is where we should check for expressions with no
980 effects. At the moment we do that in both build_x_component_expr
981 and expand_expr_stmt -- inconsistently too. For the moment
982 leave implicit void conversions unadorned so that expand_expr_stmt
983 has a chance of detecting some of the cases. */
985 expr
= build1 (CONVERT_EXPR
, void_type_node
, expr
);
990 /* Create an expression whose value is that of EXPR,
991 converted to type TYPE. The TREE_TYPE of the value
992 is always TYPE. This function implements all reasonable
993 conversions; callers should filter out those that are
994 not permitted by the language being compiled.
996 Most of this routine is from build_reinterpret_cast.
998 The backend cannot call cp_convert (what was convert) because
999 conversions to/from basetypes may involve memory references
1000 (vbases) and adding or subtracting small values (multiple
1001 inheritance), but it calls convert from the constant folding code
1002 on subtrees of already build trees after it has ripped them apart.
1004 Also, if we ever support range variables, we'll probably also have to
1005 do a little bit more work. */
1008 convert (type
, 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
))
1020 if (TREE_READONLY_DECL_P (expr
))
1021 expr
= decl_constant_value (expr
);
1022 return fold (build1 (NOP_EXPR
, type
, expr
));
1025 return ocp_convert (type
, expr
, CONV_OLD_CONVERT
,
1026 LOOKUP_NORMAL
|LOOKUP_NO_CONVERSION
);
1029 /* Like cp_convert, except permit conversions to take place which
1030 are not normally allowed due to access restrictions
1031 (such as conversion from sub-type to private super-type). */
1034 convert_force (type
, expr
, convtype
)
1039 register tree e
= expr
;
1040 register enum tree_code code
= TREE_CODE (type
);
1042 if (code
== REFERENCE_TYPE
)
1043 return fold (convert_to_reference (type
, e
, CONV_C_CAST
, LOOKUP_COMPLAIN
,
1045 else if (TREE_CODE (TREE_TYPE (e
)) == REFERENCE_TYPE
)
1046 e
= convert_from_reference (e
);
1048 if (code
== POINTER_TYPE
)
1049 return fold (convert_to_pointer_force (type
, e
));
1051 /* From typeck.c convert_for_assignment */
1052 if (((TREE_CODE (TREE_TYPE (e
)) == POINTER_TYPE
&& TREE_CODE (e
) == ADDR_EXPR
1053 && TREE_CODE (TREE_TYPE (e
)) == POINTER_TYPE
1054 && TREE_CODE (TREE_TYPE (TREE_TYPE (e
))) == METHOD_TYPE
)
1055 || integer_zerop (e
)
1056 || TYPE_PTRMEMFUNC_P (TREE_TYPE (e
)))
1057 && TYPE_PTRMEMFUNC_P (type
))
1059 /* compatible pointer to member functions. */
1060 return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type
), e
, 1);
1063 return ocp_convert (type
, e
, CONV_C_CAST
|convtype
, LOOKUP_NORMAL
);
1066 /* Convert an aggregate EXPR to type XTYPE. If a conversion
1067 exists, return the attempted conversion. This may
1068 return ERROR_MARK_NODE if the conversion is not
1069 allowed (references private members, etc).
1070 If no conversion exists, NULL_TREE is returned.
1072 If (FOR_SURE & 1) is non-zero, then we allow this type conversion
1073 to take place immediately. Otherwise, we build a SAVE_EXPR
1074 which can be evaluated if the results are ever needed.
1076 Changes to this functions should be mirrored in user_harshness.
1078 FIXME: Ambiguity checking is wrong. Should choose one by the implicit
1079 object parameter, or by the second standard conversion sequence if
1080 that doesn't do it. This will probably wait for an overloading rewrite.
1084 build_type_conversion (xtype
, expr
, for_sure
)
1088 /* C++: check to see if we can convert this aggregate type
1089 into the required type. */
1090 return build_user_type_conversion
1091 (xtype
, expr
, for_sure
? LOOKUP_NORMAL
: 0);
1094 /* Convert the given EXPR to one of a group of types suitable for use in an
1095 expression. DESIRES is a combination of various WANT_* flags (q.v.)
1096 which indicates which types are suitable. If COMPLAIN is 1, complain
1097 about ambiguity; otherwise, the caller will deal with it. */
1100 build_expr_type_conversion (desires
, expr
, complain
)
1105 tree basetype
= TREE_TYPE (expr
);
1106 tree conv
= NULL_TREE
;
1107 tree winner
= NULL_TREE
;
1109 if (expr
== null_node
1110 && (desires
& WANT_INT
)
1111 && !(desires
& WANT_NULL
))
1112 cp_warning ("converting NULL to non-pointer type");
1114 if (TREE_CODE (expr
) == OFFSET_REF
)
1115 expr
= resolve_offset_ref (expr
);
1116 expr
= convert_from_reference (expr
);
1117 basetype
= TREE_TYPE (expr
);
1119 if (! IS_AGGR_TYPE (basetype
))
1120 switch (TREE_CODE (basetype
))
1123 if ((desires
& WANT_NULL
) && null_ptr_cst_p (expr
))
1125 /* else fall through... */
1128 return (desires
& WANT_INT
) ? expr
: NULL_TREE
;
1130 return (desires
& WANT_ENUM
) ? expr
: NULL_TREE
;
1132 return (desires
& WANT_FLOAT
) ? expr
: NULL_TREE
;
1134 return (desires
& WANT_POINTER
) ? expr
: NULL_TREE
;
1138 return (desires
& WANT_POINTER
) ? default_conversion (expr
)
1144 /* The code for conversions from class type is currently only used for
1145 delete expressions. Other expressions are handled by build_new_op. */
1147 if (! TYPE_HAS_CONVERSION (basetype
))
1150 for (conv
= lookup_conversions (basetype
); conv
; conv
= TREE_CHAIN (conv
))
1154 tree cand
= TREE_VALUE (conv
);
1156 if (winner
&& winner
== cand
)
1159 candidate
= TREE_TYPE (TREE_TYPE (cand
));
1160 if (TREE_CODE (candidate
) == REFERENCE_TYPE
)
1161 candidate
= TREE_TYPE (candidate
);
1163 switch (TREE_CODE (candidate
))
1167 win
= (desires
& WANT_INT
); break;
1169 win
= (desires
& WANT_ENUM
); break;
1171 win
= (desires
& WANT_FLOAT
); break;
1173 win
= (desires
& WANT_POINTER
); break;
1185 cp_error ("ambiguous default type conversion from `%T'",
1187 cp_error (" candidate conversions include `%D' and `%D'",
1190 return error_mark_node
;
1199 tree type
= TREE_TYPE (TREE_TYPE (winner
));
1200 if (TREE_CODE (type
) == REFERENCE_TYPE
)
1201 type
= TREE_TYPE (type
);
1202 return build_user_type_conversion (type
, expr
, LOOKUP_NORMAL
);
1208 /* Implements integral promotion (4.1) and float->double promotion. */
1211 type_promotes_to (type
)
1216 if (type
== error_mark_node
)
1217 return error_mark_node
;
1219 type_quals
= CP_TYPE_QUALS (type
);
1220 type
= TYPE_MAIN_VARIANT (type
);
1222 /* bool always promotes to int (not unsigned), even if it's the same
1224 if (type
== boolean_type_node
)
1225 type
= integer_type_node
;
1227 /* Normally convert enums to int, but convert wide enums to something
1229 else if (TREE_CODE (type
) == ENUMERAL_TYPE
1230 || type
== wchar_type_node
)
1232 int precision
= MAX (TYPE_PRECISION (type
),
1233 TYPE_PRECISION (integer_type_node
));
1234 tree totype
= type_for_size (precision
, 0);
1235 if (TREE_UNSIGNED (type
)
1236 && ! int_fits_type_p (TYPE_MAX_VALUE (type
), totype
))
1237 type
= type_for_size (precision
, 1);
1241 else if (C_PROMOTING_INTEGER_TYPE_P (type
))
1243 /* Retain unsignedness if really not getting bigger. */
1244 if (TREE_UNSIGNED (type
)
1245 && TYPE_PRECISION (type
) == TYPE_PRECISION (integer_type_node
))
1246 type
= unsigned_type_node
;
1248 type
= integer_type_node
;
1250 else if (type
== float_type_node
)
1251 type
= double_type_node
;
1253 return cp_build_qualified_type (type
, type_quals
);
1256 /* The routines below this point are carefully written to conform to
1257 the standard. They use the same terminology, and follow the rules
1258 closely. Although they are used only in pt.c at the moment, they
1259 should presumably be used everywhere in the future. */
1261 /* Attempt to perform qualification conversions on EXPR to convert it
1262 to TYPE. Return the resulting expression, or error_mark_node if
1263 the conversion was impossible. */
1266 perform_qualification_conversions (type
, expr
)
1270 if (TREE_CODE (type
) == POINTER_TYPE
1271 && TREE_CODE (TREE_TYPE (expr
)) == POINTER_TYPE
1272 && comp_ptr_ttypes (TREE_TYPE (type
), TREE_TYPE (TREE_TYPE (expr
))))
1273 return build1 (NOP_EXPR
, type
, expr
);
1275 return error_mark_node
;