2004-08-26 Matthias Klose <doko@debian.org>
[official-gcc.git] / gcc / cp / except.c
blob72ce2867d290f027256394b90979deb6b6d66a3b
1 /* Handle exceptional things in C++.
2 Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
4 Contributed by Michael Tiemann <tiemann@cygnus.com>
5 Rewritten by Mike Stump <mrs@cygnus.com>, based upon an
6 initial re-implementation courtesy Tad Hunt.
8 This file is part of GCC.
10 GCC is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 2, or (at your option)
13 any later version.
15 GCC is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
20 You should have received a copy of the GNU General Public License
21 along with GCC; see the file COPYING. If not, write to
22 the Free Software Foundation, 59 Temple Place - Suite 330,
23 Boston, MA 02111-1307, USA. */
26 #include "config.h"
27 #include "system.h"
28 #include "coretypes.h"
29 #include "tm.h"
30 #include "tree.h"
31 #include "rtl.h"
32 #include "expr.h"
33 #include "libfuncs.h"
34 #include "cp-tree.h"
35 #include "flags.h"
36 #include "output.h"
37 #include "except.h"
38 #include "toplev.h"
39 #include "tree-inline.h"
40 #include "tree-iterator.h"
42 static void push_eh_cleanup (tree);
43 static tree prepare_eh_type (tree);
44 static tree build_eh_type_type (tree);
45 static tree do_begin_catch (void);
46 static int dtor_nothrow (tree);
47 static tree do_end_catch (tree);
48 static bool decl_is_java_type (tree decl, int err);
49 static void initialize_handler_parm (tree, tree);
50 static tree do_allocate_exception (tree);
51 static tree wrap_cleanups_r (tree *, int *, void *);
52 static int complete_ptr_ref_or_void_ptr_p (tree, tree);
53 static bool is_admissible_throw_operand (tree);
54 static int can_convert_eh (tree, tree);
55 static tree cp_protect_cleanup_actions (void);
57 /* Sets up all the global eh stuff that needs to be initialized at the
58 start of compilation. */
60 void
61 init_exception_processing (void)
63 tree tmp;
65 /* void std::terminate (); */
66 push_namespace (std_identifier);
67 tmp = build_function_type (void_type_node, void_list_node);
68 terminate_node = build_cp_library_fn_ptr ("terminate", tmp);
69 TREE_THIS_VOLATILE (terminate_node) = 1;
70 TREE_NOTHROW (terminate_node) = 1;
71 pop_namespace ();
73 /* void __cxa_call_unexpected(void *); */
74 tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
75 tmp = build_function_type (void_type_node, tmp);
76 call_unexpected_node
77 = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp);
79 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
80 ? "__gxx_personality_sj0"
81 : "__gxx_personality_v0");
83 lang_eh_runtime_type = build_eh_type_type;
84 lang_protect_cleanup_actions = &cp_protect_cleanup_actions;
87 /* Returns an expression to be executed if an unhandled exception is
88 propagated out of a cleanup region. */
90 static tree
91 cp_protect_cleanup_actions (void)
93 /* [except.terminate]
95 When the destruction of an object during stack unwinding exits
96 using an exception ... void terminate(); is called. */
97 return build_call (terminate_node, NULL_TREE);
100 static tree
101 prepare_eh_type (tree type)
103 if (type == NULL_TREE)
104 return type;
105 if (type == error_mark_node)
106 return error_mark_node;
108 /* peel back references, so they match. */
109 type = non_reference (type);
111 /* Peel off cv qualifiers. */
112 type = TYPE_MAIN_VARIANT (type);
114 return type;
117 /* Return the type info for TYPE as used by EH machinery. */
118 tree
119 eh_type_info (tree type)
121 tree exp;
123 if (type == NULL_TREE || type == error_mark_node)
124 return type;
126 if (decl_is_java_type (type, 0))
127 exp = build_java_class_ref (TREE_TYPE (type));
128 else
129 exp = get_tinfo_decl (type);
131 return exp;
134 /* Build the address of a typeinfo decl for use in the runtime
135 matching field of the exception model. */
137 static tree
138 build_eh_type_type (tree type)
140 tree exp = eh_type_info (type);
142 if (!exp)
143 return NULL;
145 mark_used (exp);
147 return convert (ptr_type_node, build_address (exp));
150 tree
151 build_exc_ptr (void)
153 return build0 (EXC_PTR_EXPR, ptr_type_node);
156 /* Build up a call to __cxa_begin_catch, to tell the runtime that the
157 exception has been handled. */
159 static tree
160 do_begin_catch (void)
162 tree fn;
164 fn = get_identifier ("__cxa_begin_catch");
165 if (!get_global_value_if_present (fn, &fn))
167 /* Declare void* __cxa_begin_catch (void *). */
168 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
169 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
172 return build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
173 NULL_TREE));
176 /* Returns nonzero if cleaning up an exception of type TYPE (which can be
177 NULL_TREE for a ... handler) will not throw an exception. */
179 static int
180 dtor_nothrow (tree type)
182 if (type == NULL_TREE)
183 return 0;
185 if (! TYPE_HAS_DESTRUCTOR (type))
186 return 1;
188 return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type));
191 /* Build up a call to __cxa_end_catch, to destroy the exception object
192 for the current catch block if no others are currently using it. */
194 static tree
195 do_end_catch (tree type)
197 tree fn, cleanup;
199 fn = get_identifier ("__cxa_end_catch");
200 if (!get_global_value_if_present (fn, &fn))
202 /* Declare void __cxa_end_catch (). */
203 fn = push_void_library_fn (fn, void_list_node);
204 /* This can throw if the destructor for the exception throws. */
205 TREE_NOTHROW (fn) = 0;
208 cleanup = build_function_call (fn, NULL_TREE);
209 TREE_NOTHROW (cleanup) = dtor_nothrow (type);
211 return cleanup;
214 /* This routine creates the cleanup for the current exception. */
216 static void
217 push_eh_cleanup (tree type)
219 finish_decl_cleanup (NULL_TREE, do_end_catch (type));
222 /* Return nonzero value if DECL is a Java type suitable for catch or
223 throw. */
225 static bool
226 decl_is_java_type (tree decl, int err)
228 bool r = (TREE_CODE (decl) == POINTER_TYPE
229 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
230 && TYPE_FOR_JAVA (TREE_TYPE (decl)));
232 if (err)
234 if (TREE_CODE (decl) == REFERENCE_TYPE
235 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
236 && TYPE_FOR_JAVA (TREE_TYPE (decl)))
238 /* Can't throw a reference. */
239 error ("type `%T' is disallowed in Java `throw' or `catch'",
240 decl);
243 if (r)
245 tree jthrow_node
246 = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));
248 if (jthrow_node == NULL_TREE)
249 fatal_error
250 ("call to Java `catch' or `throw' with `jthrowable' undefined");
252 jthrow_node = TREE_TYPE (TREE_TYPE (jthrow_node));
254 if (! DERIVED_FROM_P (jthrow_node, TREE_TYPE (decl)))
256 /* Thrown object must be a Throwable. */
257 error ("type `%T' is not derived from `java::lang::Throwable'",
258 TREE_TYPE (decl));
263 return r;
266 /* Select the personality routine to be used for exception handling,
267 or issue an error if we need two different ones in the same
268 translation unit.
269 ??? At present eh_personality_libfunc is set to
270 __gxx_personality_(sj|v)0 in init_exception_processing - should it
271 be done here instead? */
272 void
273 choose_personality_routine (enum languages lang)
275 static enum {
276 chose_none,
277 chose_cpp,
278 chose_java,
279 gave_error
280 } state;
282 switch (state)
284 case gave_error:
285 return;
287 case chose_cpp:
288 if (lang != lang_cplusplus)
289 goto give_error;
290 return;
292 case chose_java:
293 if (lang != lang_java)
294 goto give_error;
295 return;
297 case chose_none:
298 ; /* Proceed to language selection. */
301 switch (lang)
303 case lang_cplusplus:
304 state = chose_cpp;
305 break;
307 case lang_java:
308 state = chose_java;
309 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
310 ? "__gcj_personality_sj0"
311 : "__gcj_personality_v0");
312 break;
314 default:
315 abort ();
317 return;
319 give_error:
320 error ("mixing C++ and Java catches in a single translation unit");
321 state = gave_error;
324 /* Initialize the catch parameter DECL. */
326 static void
327 initialize_handler_parm (tree decl, tree exp)
329 tree init;
330 tree init_type;
332 /* Make sure we mark the catch param as used, otherwise we'll get a
333 warning about an unused ((anonymous)). */
334 TREE_USED (decl) = 1;
336 /* Figure out the type that the initializer is. Pointers are returned
337 adjusted by value from __cxa_begin_catch. Others are returned by
338 reference. */
339 init_type = TREE_TYPE (decl);
340 if (! TYPE_PTR_P (init_type)
341 && TREE_CODE (init_type) != REFERENCE_TYPE)
342 init_type = build_reference_type (init_type);
344 choose_personality_routine (decl_is_java_type (init_type, 0)
345 ? lang_java : lang_cplusplus);
347 /* Since pointers are passed by value, initialize a reference to
348 pointer catch parm with the address of the temporary. */
349 if (TREE_CODE (init_type) == REFERENCE_TYPE
350 && TYPE_PTR_P (TREE_TYPE (init_type)))
351 exp = build_unary_op (ADDR_EXPR, exp, 1);
353 exp = ocp_convert (init_type, exp, CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
355 init = convert_from_reference (exp);
357 /* If the constructor for the catch parm exits via an exception, we
358 must call terminate. See eh23.C. */
359 if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
361 /* Generate the copy constructor call directly so we can wrap it.
362 See also expand_default_init. */
363 init = ocp_convert (TREE_TYPE (decl), init,
364 CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
365 init = build1 (MUST_NOT_THROW_EXPR, TREE_TYPE (init), init);
368 /* Let `cp_finish_decl' know that this initializer is ok. */
369 DECL_INITIAL (decl) = error_mark_node;
370 decl = pushdecl (decl);
372 start_decl_1 (decl);
373 cp_finish_decl (decl, init, NULL_TREE,
374 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
377 /* Call this to start a catch block. DECL is the catch parameter. */
379 tree
380 expand_start_catch_block (tree decl)
382 tree exp = NULL_TREE;
383 tree type;
384 bool is_java;
386 if (! doing_eh (1))
387 return NULL_TREE;
389 /* Make sure this declaration is reasonable. */
390 if (decl && !complete_ptr_ref_or_void_ptr_p (TREE_TYPE (decl), NULL_TREE))
391 decl = NULL_TREE;
393 if (decl)
394 type = prepare_eh_type (TREE_TYPE (decl));
395 else
396 type = NULL_TREE;
398 is_java = false;
399 if (decl)
401 tree init;
403 if (decl_is_java_type (type, 1))
405 /* Java only passes object via pointer and doesn't require
406 adjusting. The java object is immediately before the
407 generic exception header. */
408 init = build_exc_ptr ();
409 init = build1 (NOP_EXPR, build_pointer_type (type), init);
410 init = build2 (MINUS_EXPR, TREE_TYPE (init), init,
411 TYPE_SIZE_UNIT (TREE_TYPE (init)));
412 init = build_indirect_ref (init, NULL);
413 is_java = true;
415 else
417 /* C++ requires that we call __cxa_begin_catch to get the
418 pointer to the actual object. */
419 init = do_begin_catch ();
422 exp = create_temporary_var (ptr_type_node);
423 DECL_REGISTER (exp) = 1;
424 cp_finish_decl (exp, init, NULL_TREE, LOOKUP_ONLYCONVERTING);
425 finish_expr_stmt (build_modify_expr (exp, INIT_EXPR, init));
427 else
428 finish_expr_stmt (do_begin_catch ());
430 /* C++ requires that we call __cxa_end_catch at the end of
431 processing the exception. */
432 if (! is_java)
433 push_eh_cleanup (type);
435 if (decl)
436 initialize_handler_parm (decl, exp);
438 return type;
442 /* Call this to end a catch block. Its responsible for emitting the
443 code to handle jumping back to the correct place, and for emitting
444 the label to jump to if this catch block didn't match. */
446 void
447 expand_end_catch_block (void)
449 if (! doing_eh (1))
450 return;
452 /* The exception being handled is rethrown if control reaches the end of
453 a handler of the function-try-block of a constructor or destructor. */
454 if (in_function_try_handler
455 && (DECL_CONSTRUCTOR_P (current_function_decl)
456 || DECL_DESTRUCTOR_P (current_function_decl)))
457 finish_expr_stmt (build_throw (NULL_TREE));
460 tree
461 begin_eh_spec_block (void)
463 tree r = build_stmt (EH_SPEC_BLOCK, NULL_TREE, NULL_TREE);
464 add_stmt (r);
465 EH_SPEC_STMTS (r) = push_stmt_list ();
466 return r;
469 void
470 finish_eh_spec_block (tree raw_raises, tree eh_spec_block)
472 tree raises;
474 EH_SPEC_STMTS (eh_spec_block) = pop_stmt_list (EH_SPEC_STMTS (eh_spec_block));
476 /* Strip cv quals, etc, from the specification types. */
477 for (raises = NULL_TREE;
478 raw_raises && TREE_VALUE (raw_raises);
479 raw_raises = TREE_CHAIN (raw_raises))
481 tree type = prepare_eh_type (TREE_VALUE (raw_raises));
482 tree tinfo = eh_type_info (type);
484 mark_used (tinfo);
485 raises = tree_cons (NULL_TREE, type, raises);
488 EH_SPEC_RAISES (eh_spec_block) = raises;
491 /* Return a pointer to a buffer for an exception object of type TYPE. */
493 static tree
494 do_allocate_exception (tree type)
496 tree fn;
498 fn = get_identifier ("__cxa_allocate_exception");
499 if (!get_global_value_if_present (fn, &fn))
501 /* Declare void *__cxa_allocate_exception(size_t). */
502 tree tmp = tree_cons (NULL_TREE, size_type_node, void_list_node);
503 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
506 return build_function_call (fn, tree_cons (NULL_TREE, size_in_bytes (type),
507 NULL_TREE));
510 /* Call __cxa_free_exception from a cleanup. This is never invoked
511 directly, but see the comment for stabilize_throw_expr. */
513 static tree
514 do_free_exception (tree ptr)
516 tree fn;
518 fn = get_identifier ("__cxa_free_exception");
519 if (!get_global_value_if_present (fn, &fn))
521 /* Declare void __cxa_free_exception (void *). */
522 fn = push_void_library_fn (fn, tree_cons (NULL_TREE, ptr_type_node,
523 void_list_node));
526 return build_function_call (fn, tree_cons (NULL_TREE, ptr, NULL_TREE));
529 /* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
530 Called from build_throw via walk_tree_without_duplicates. */
532 static tree
533 wrap_cleanups_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
534 void *data ATTRIBUTE_UNUSED)
536 tree exp = *tp;
537 tree cleanup;
539 /* Don't walk into types. */
540 if (TYPE_P (exp))
542 *walk_subtrees = 0;
543 return NULL_TREE;
545 if (TREE_CODE (exp) != TARGET_EXPR)
546 return NULL_TREE;
548 cleanup = TARGET_EXPR_CLEANUP (exp);
549 if (cleanup)
551 cleanup = build1 (MUST_NOT_THROW_EXPR, void_type_node, cleanup);
552 TARGET_EXPR_CLEANUP (exp) = cleanup;
555 /* Keep iterating. */
556 return NULL_TREE;
559 /* Build a throw expression. */
561 tree
562 build_throw (tree exp)
564 tree fn;
566 if (exp == error_mark_node)
567 return exp;
569 if (processing_template_decl)
571 current_function_returns_abnormally = 1;
572 return build_min (THROW_EXPR, void_type_node, exp);
575 if (exp == null_node)
576 warning ("throwing NULL, which has integral, not pointer type");
578 if (exp != NULL_TREE)
580 if (!is_admissible_throw_operand (exp))
581 return error_mark_node;
584 if (! doing_eh (1))
585 return error_mark_node;
587 if (exp && decl_is_java_type (TREE_TYPE (exp), 1))
589 tree fn = get_identifier ("_Jv_Throw");
590 if (!get_global_value_if_present (fn, &fn))
592 /* Declare void _Jv_Throw (void *). */
593 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
594 tmp = build_function_type (ptr_type_node, tmp);
595 fn = push_throw_library_fn (fn, tmp);
597 else if (really_overloaded_fn (fn))
599 error ("`%D' should never be overloaded", fn);
600 return error_mark_node;
602 fn = OVL_CURRENT (fn);
603 exp = build_function_call (fn, tree_cons (NULL_TREE, exp, NULL_TREE));
605 else if (exp)
607 tree throw_type;
608 tree cleanup;
609 tree object, ptr;
610 tree tmp;
611 tree temp_expr, allocate_expr;
612 bool elided;
614 /* The CLEANUP_TYPE is the internal type of a destructor. */
615 if (!cleanup_type)
617 tmp = void_list_node;
618 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
619 tmp = build_function_type (void_type_node, tmp);
620 cleanup_type = build_pointer_type (tmp);
623 fn = get_identifier ("__cxa_throw");
624 if (!get_global_value_if_present (fn, &fn))
626 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
627 /* ??? Second argument is supposed to be "std::type_info*". */
628 tmp = void_list_node;
629 tmp = tree_cons (NULL_TREE, cleanup_type, tmp);
630 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
631 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
632 tmp = build_function_type (void_type_node, tmp);
633 fn = push_throw_library_fn (fn, tmp);
636 /* throw expression */
637 /* First, decay it. */
638 exp = decay_conversion (exp);
640 /* OK, this is kind of wacky. The standard says that we call
641 terminate when the exception handling mechanism, after
642 completing evaluation of the expression to be thrown but
643 before the exception is caught (_except.throw_), calls a
644 user function that exits via an uncaught exception.
646 So we have to protect the actual initialization of the
647 exception object with terminate(), but evaluate the
648 expression first. Since there could be temps in the
649 expression, we need to handle that, too. We also expand
650 the call to __cxa_allocate_exception first (which doesn't
651 matter, since it can't throw). */
653 /* Allocate the space for the exception. */
654 allocate_expr = do_allocate_exception (TREE_TYPE (exp));
655 allocate_expr = get_target_expr (allocate_expr);
656 ptr = TARGET_EXPR_SLOT (allocate_expr);
657 object = build1 (NOP_EXPR, build_pointer_type (TREE_TYPE (exp)), ptr);
658 object = build_indirect_ref (object, NULL);
660 elided = (TREE_CODE (exp) == TARGET_EXPR);
662 /* And initialize the exception object. */
663 exp = build_init (object, exp, LOOKUP_ONLYCONVERTING);
664 if (exp == error_mark_node)
666 error (" in thrown expression");
667 return error_mark_node;
670 /* Pre-evaluate the thrown expression first, since if we allocated
671 the space first we would have to deal with cleaning it up if
672 evaluating this expression throws.
674 The case where EXP the initializer is a call to a constructor or a
675 function returning a class is a bit of a grey area in the
676 standard; it's unclear whether or not it should be allowed to
677 throw. We used to say no, as that allowed us to optimize this
678 case without worrying about deallocating the exception object if
679 it does. But that conflicted with expectations (PR 13944) and the
680 EDG compiler; now we wrap the initialization in a TRY_CATCH_EXPR
681 to call do_free_exception rather than in a MUST_NOT_THROW_EXPR,
682 for this case only.
684 Note that we don't check the return value from stabilize_init
685 because it will only return false in cases where elided is true,
686 and therefore we don't need to work around the failure to
687 preevaluate. */
688 temp_expr = NULL_TREE;
689 stabilize_init (exp, &temp_expr);
691 if (elided)
692 exp = build2 (TRY_CATCH_EXPR, void_type_node, exp,
693 do_free_exception (ptr));
694 else
695 exp = build1 (MUST_NOT_THROW_EXPR, void_type_node, exp);
697 /* Prepend the allocation. */
698 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), allocate_expr, exp);
699 if (temp_expr)
701 /* Prepend the calculation of the throw expression. Also, force
702 any cleanups from the expression to be evaluated here so that
703 we don't have to do them during unwinding. But first wrap
704 them in MUST_NOT_THROW_EXPR, since they are run after the
705 exception object is initialized. */
706 walk_tree_without_duplicates (&temp_expr, wrap_cleanups_r, 0);
707 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), temp_expr, exp);
708 exp = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (exp), exp);
711 throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object)));
713 if (TYPE_HAS_DESTRUCTOR (TREE_TYPE (object)))
715 cleanup = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)),
716 complete_dtor_identifier, 0);
717 cleanup = BASELINK_FUNCTIONS (cleanup);
718 mark_used (cleanup);
719 cxx_mark_addressable (cleanup);
720 /* Pretend it's a normal function. */
721 cleanup = build1 (ADDR_EXPR, cleanup_type, cleanup);
723 else
724 cleanup = build_int_cst (cleanup_type, 0);
726 tmp = tree_cons (NULL_TREE, cleanup, NULL_TREE);
727 tmp = tree_cons (NULL_TREE, throw_type, tmp);
728 tmp = tree_cons (NULL_TREE, ptr, tmp);
729 /* ??? Indicate that this function call throws throw_type. */
730 tmp = build_function_call (fn, tmp);
732 /* Tack on the initialization stuff. */
733 exp = build2 (COMPOUND_EXPR, TREE_TYPE (tmp), exp, tmp);
735 else
737 /* Rethrow current exception. */
739 tree fn = get_identifier ("__cxa_rethrow");
740 if (!get_global_value_if_present (fn, &fn))
742 /* Declare void __cxa_rethrow (void). */
743 fn = push_throw_library_fn
744 (fn, build_function_type (void_type_node, void_list_node));
747 /* ??? Indicate that this function call allows exceptions of the type
748 of the enclosing catch block (if known). */
749 exp = build_function_call (fn, NULL_TREE);
752 exp = build1 (THROW_EXPR, void_type_node, exp);
754 return exp;
757 /* Make sure TYPE is complete, pointer to complete, reference to
758 complete, or pointer to cv void. Issue diagnostic on failure.
759 Return the zero on failure and nonzero on success. FROM can be
760 the expr or decl from whence TYPE came, if available. */
762 static int
763 complete_ptr_ref_or_void_ptr_p (tree type, tree from)
765 int is_ptr;
767 /* Check complete. */
768 type = complete_type_or_else (type, from);
769 if (!type)
770 return 0;
772 /* Or a pointer or ref to one, or cv void *. */
773 is_ptr = TREE_CODE (type) == POINTER_TYPE;
774 if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE)
776 tree core = TREE_TYPE (type);
778 if (is_ptr && VOID_TYPE_P (core))
779 /* OK */;
780 else if (!complete_type_or_else (core, from))
781 return 0;
783 return 1;
786 /* Return truth-value if EXPRESSION is admissible in throw-expression,
787 i.e. if it is not of incomplete type or a pointer/reference to such
788 a type or of an abstract class type. */
790 static bool
791 is_admissible_throw_operand (tree expr)
793 tree type = TREE_TYPE (expr);
795 /* 15.1/4 [...] The type of the throw-expression shall not be an
796 incomplete type, or a pointer or a reference to an incomplete
797 type, other than void*, const void*, volatile void*, or
798 const volatile void*. Except for these restriction and the
799 restrictions on type matching mentioned in 15.3, the operand
800 of throw is treated exactly as a function argument in a call
801 (5.2.2) or the operand of a return statement. */
802 if (!complete_ptr_ref_or_void_ptr_p (type, expr))
803 return false;
805 /* 10.4/3 An abstract class shall not be used as a parameter type,
806 as a function return type or as type of an explicit
807 conversion. */
808 else if (CLASS_TYPE_P (type) && CLASSTYPE_PURE_VIRTUALS (type))
810 error ("expression '%E' of abstract class type '%T' cannot be used in throw-expression", expr, type);
811 return false;
814 return true;
817 /* Returns nonzero if FN is a declaration of a standard C library
818 function which is known not to throw.
820 [lib.res.on.exception.handling]: None of the functions from the
821 Standard C library shall report an error by throwing an
822 exception, unless it calls a program-supplied function that
823 throws an exception. */
825 #include "cfns.h"
828 nothrow_libfn_p (tree fn)
830 tree id;
832 if (TREE_PUBLIC (fn)
833 && DECL_EXTERNAL (fn)
834 && DECL_NAMESPACE_SCOPE_P (fn)
835 && DECL_EXTERN_C_P (fn))
836 /* OK */;
837 else
838 /* Can't be a C library function. */
839 return 0;
841 /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME
842 unless the system headers are playing rename tricks, and if
843 they are, we don't want to be confused by them. */
844 id = DECL_NAME (fn);
845 return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id));
848 /* Returns nonzero if an exception of type FROM will be caught by a
849 handler for type TO, as per [except.handle]. */
851 static int
852 can_convert_eh (tree to, tree from)
854 to = non_reference (to);
855 from = non_reference (from);
857 if (TREE_CODE (to) == POINTER_TYPE && TREE_CODE (from) == POINTER_TYPE)
859 to = TREE_TYPE (to);
860 from = TREE_TYPE (from);
862 if (! at_least_as_qualified_p (to, from))
863 return 0;
865 if (TREE_CODE (to) == VOID_TYPE)
866 return 1;
868 /* Else fall through. */
871 if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
872 && PUBLICLY_UNIQUELY_DERIVED_P (to, from))
873 return 1;
875 return 0;
878 /* Check whether any of the handlers in I are shadowed by another handler
879 accepting TYPE. Note that the shadowing may not be complete; even if
880 an exception of type B would be caught by a handler for A, there could
881 be a derived class C for which A is an ambiguous base but B is not, so
882 the handler for B would catch an exception of type C. */
884 static void
885 check_handlers_1 (tree master, tree_stmt_iterator i)
887 tree type = TREE_TYPE (master);
889 for (; !tsi_end_p (i); tsi_next (&i))
891 tree handler = tsi_stmt (i);
892 if (TREE_TYPE (handler) && can_convert_eh (type, TREE_TYPE (handler)))
894 warning ("%Hexception of type `%T' will be caught",
895 EXPR_LOCUS (handler), TREE_TYPE (handler));
896 warning ("%H by earlier handler for `%T'",
897 EXPR_LOCUS (master), type);
898 break;
903 /* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK. */
905 void
906 check_handlers (tree handlers)
908 tree_stmt_iterator i;
910 /* If we don't have a STATEMENT_LIST, then we've just got one
911 handler, and thus nothing to warn about. */
912 if (TREE_CODE (handlers) != STATEMENT_LIST)
913 return;
915 i = tsi_start (handlers);
916 if (!tsi_end_p (i))
917 while (1)
919 tree handler = tsi_stmt (i);
920 tsi_next (&i);
922 /* No more handlers; nothing to shadow. */
923 if (tsi_end_p (i))
924 break;
925 if (TREE_TYPE (handler) == NULL_TREE)
926 pedwarn ("%H`...' handler must be the last handler for"
927 " its try block", EXPR_LOCUS (handler));
928 else
929 check_handlers_1 (handler, i);