1 /* Handle exceptional things in C++.
2 Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003 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)
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. */
28 #include "coretypes.h"
39 #include "tree-inline.h"
41 static void push_eh_cleanup (tree);
42 static tree prepare_eh_type (tree);
43 static tree build_eh_type_type (tree);
44 static tree do_begin_catch (void);
45 static int dtor_nothrow (tree);
46 static tree do_end_catch (tree);
47 static bool decl_is_java_type (tree decl, int err);
48 static void initialize_handler_parm (tree, tree);
49 static tree do_allocate_exception (tree);
50 static tree stabilize_throw_expr (tree, 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 void check_handlers_1 (tree, tree);
56 static tree cp_protect_cleanup_actions (void);
58 /* Sets up all the global eh stuff that needs to be initialized at the
59 start of compilation. */
62 init_exception_processing (void)
66 /* void std::terminate (); */
67 push_namespace (std_identifier);
68 tmp = build_function_type (void_type_node, void_list_node);
69 terminate_node = build_cp_library_fn_ptr ("terminate", tmp);
70 TREE_THIS_VOLATILE (terminate_node) = 1;
71 TREE_NOTHROW (terminate_node) = 1;
74 /* void __cxa_call_unexpected(void *); */
75 tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
76 tmp = build_function_type (void_type_node, tmp);
78 = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp);
80 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
81 ? "__gxx_personality_sj0"
82 : "__gxx_personality_v0");
84 lang_eh_runtime_type = build_eh_type_type;
85 lang_protect_cleanup_actions = &cp_protect_cleanup_actions;
88 /* Returns an expression to be executed if an unhandled exception is
89 propagated out of a cleanup region. */
92 cp_protect_cleanup_actions (void)
96 When the destruction of an object during stack unwinding exits
97 using an exception ... void terminate(); is called. */
98 return build_call (terminate_node, NULL_TREE);
102 prepare_eh_type (tree type)
104 if (type == NULL_TREE)
106 if (type == error_mark_node)
107 return error_mark_node;
109 /* peel back references, so they match. */
110 type = non_reference (type);
112 /* Peel off cv qualifiers. */
113 type = TYPE_MAIN_VARIANT (type);
118 /* Return the type info for TYPE as used by EH machinery. */
120 eh_type_info (tree type)
124 if (type == NULL_TREE || type == error_mark_node)
127 if (decl_is_java_type (type, 0))
128 exp = build_java_class_ref (TREE_TYPE (type));
130 exp = get_tinfo_decl (type);
135 /* Build the address of a typeinfo decl for use in the runtime
136 matching field of the exception model. */
139 build_eh_type_type (tree type)
141 tree exp = eh_type_info (type);
148 return build1 (ADDR_EXPR, ptr_type_node, exp);
154 return build (EXC_PTR_EXPR, ptr_type_node);
157 /* Build up a call to __cxa_begin_catch, to tell the runtime that the
158 exception has been handled. */
161 do_begin_catch (void)
165 fn = get_identifier ("__cxa_begin_catch");
166 if (!get_global_value_if_present (fn, &fn))
168 /* Declare void* __cxa_begin_catch (void *). */
169 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
170 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
173 return build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
177 /* Returns nonzero if cleaning up an exception of type TYPE (which can be
178 NULL_TREE for a ... handler) will not throw an exception. */
181 dtor_nothrow (tree type)
183 if (type == NULL_TREE)
186 if (! TYPE_HAS_DESTRUCTOR (type))
189 return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type));
192 /* Build up a call to __cxa_end_catch, to destroy the exception object
193 for the current catch block if no others are currently using it. */
196 do_end_catch (tree type)
200 fn = get_identifier ("__cxa_end_catch");
201 if (!get_global_value_if_present (fn, &fn))
203 /* Declare void __cxa_end_catch (). */
204 fn = push_void_library_fn (fn, void_list_node);
205 /* This can throw if the destructor for the exception throws. */
206 TREE_NOTHROW (fn) = 0;
209 cleanup = build_function_call (fn, NULL_TREE);
210 TREE_NOTHROW (cleanup) = dtor_nothrow (type);
215 /* This routine creates the cleanup for the current exception. */
218 push_eh_cleanup (tree type)
220 finish_decl_cleanup (NULL_TREE, do_end_catch (type));
223 /* Return nonzero value if DECL is a Java type suitable for catch or
227 decl_is_java_type (tree decl, int err)
229 bool r = (TREE_CODE (decl) == POINTER_TYPE
230 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
231 && TYPE_FOR_JAVA (TREE_TYPE (decl)));
235 if (TREE_CODE (decl) == REFERENCE_TYPE
236 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
237 && TYPE_FOR_JAVA (TREE_TYPE (decl)))
239 /* Can't throw a reference. */
240 error ("type `%T' is disallowed in Java `throw' or `catch'",
247 = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));
249 if (jthrow_node == NULL_TREE)
251 ("call to Java `catch' or `throw' with `jthrowable' undefined");
253 jthrow_node = TREE_TYPE (TREE_TYPE (jthrow_node));
255 if (! DERIVED_FROM_P (jthrow_node, TREE_TYPE (decl)))
257 /* Thrown object must be a Throwable. */
258 error ("type `%T' is not derived from `java::lang::Throwable'",
267 /* Select the personality routine to be used for exception handling,
268 or issue an error if we need two different ones in the same
270 ??? At present eh_personality_libfunc is set to
271 __gxx_personality_(sj|v)0 in init_exception_processing - should it
272 be done here instead? */
274 choose_personality_routine (enum languages lang)
289 if (lang != lang_cplusplus)
294 if (lang != lang_java)
299 ; /* proceed to language selection */
310 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
311 ? "__gcj_personality_sj0"
312 : "__gcj_personality_v0");
321 error ("mixing C++ and Java catches in a single translation unit");
325 /* Initialize the catch parameter DECL. */
328 initialize_handler_parm (tree decl, tree exp)
333 /* Make sure we mark the catch param as used, otherwise we'll get a
334 warning about an unused ((anonymous)). */
335 TREE_USED (decl) = 1;
337 /* Figure out the type that the initializer is. Pointers are returned
338 adjusted by value from __cxa_begin_catch. Others are returned by
340 init_type = TREE_TYPE (decl);
341 if (! TYPE_PTR_P (init_type)
342 && TREE_CODE (init_type) != REFERENCE_TYPE)
343 init_type = build_reference_type (init_type);
345 choose_personality_routine (decl_is_java_type (init_type, 0)
346 ? lang_java : lang_cplusplus);
348 /* Since pointers are passed by value, initialize a reference to
349 pointer catch parm with the address of the temporary. */
350 if (TREE_CODE (init_type) == REFERENCE_TYPE
351 && TYPE_PTR_P (TREE_TYPE (init_type)))
352 exp = build_unary_op (ADDR_EXPR, exp, 1);
354 exp = ocp_convert (init_type, exp, CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
356 init = convert_from_reference (exp);
358 /* If the constructor for the catch parm exits via an exception, we
359 must call terminate. See eh23.C. */
360 if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
362 /* Generate the copy constructor call directly so we can wrap it.
363 See also expand_default_init. */
364 init = ocp_convert (TREE_TYPE (decl), init,
365 CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
366 init = build1 (MUST_NOT_THROW_EXPR, TREE_TYPE (init), init);
369 /* Let `cp_finish_decl' know that this initializer is ok. */
370 DECL_INITIAL (decl) = error_mark_node;
371 decl = pushdecl (decl);
374 cp_finish_decl (decl, init, NULL_TREE,
375 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
378 /* Call this to start a catch block. DECL is the catch parameter. */
381 expand_start_catch_block (tree decl)
383 tree exp = NULL_TREE;
390 /* Make sure this declaration is reasonable. */
391 if (decl && !complete_ptr_ref_or_void_ptr_p (TREE_TYPE (decl), NULL_TREE))
395 type = prepare_eh_type (TREE_TYPE (decl));
404 if (decl_is_java_type (type, 1))
406 /* Java only passes object via pointer and doesn't require
407 adjusting. The java object is immediately before the
408 generic exception header. */
409 init = build_exc_ptr ();
410 init = build1 (NOP_EXPR, build_pointer_type (type), init);
411 init = build (MINUS_EXPR, TREE_TYPE (init), init,
412 TYPE_SIZE_UNIT (TREE_TYPE (init)));
413 init = build_indirect_ref (init, NULL);
418 /* C++ requires that we call __cxa_begin_catch to get the
419 pointer to the actual object. */
420 init = do_begin_catch ();
423 exp = create_temporary_var (ptr_type_node);
424 DECL_REGISTER (exp) = 1;
425 cp_finish_decl (exp, init, NULL_TREE, LOOKUP_ONLYCONVERTING);
426 finish_expr_stmt (build_modify_expr (exp, INIT_EXPR, init));
429 finish_expr_stmt (do_begin_catch ());
431 /* C++ requires that we call __cxa_end_catch at the end of
432 processing the exception. */
434 push_eh_cleanup (type);
437 initialize_handler_parm (decl, exp);
443 /* Call this to end a catch block. Its responsible for emitting the
444 code to handle jumping back to the correct place, and for emitting
445 the label to jump to if this catch block didn't match. */
448 expand_end_catch_block (void)
453 /* The exception being handled is rethrown if control reaches the end of
454 a handler of the function-try-block of a constructor or destructor. */
455 if (in_function_try_handler
456 && (DECL_CONSTRUCTOR_P (current_function_decl)
457 || DECL_DESTRUCTOR_P (current_function_decl)))
458 finish_expr_stmt (build_throw (NULL_TREE));
462 begin_eh_spec_block (void)
464 tree r = build_stmt (EH_SPEC_BLOCK, NULL_TREE, NULL_TREE);
470 finish_eh_spec_block (tree raw_raises, tree eh_spec_block)
474 RECHAIN_STMTS (eh_spec_block, 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);
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. */
494 do_allocate_exception (tree type)
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),
511 /* Call __cxa_free_exception from a cleanup. This is never invoked
512 directly, but see the comment for stabilize_throw_expr. */
515 do_free_exception (tree ptr)
519 fn = get_identifier ("__cxa_free_exception");
520 if (!get_global_value_if_present (fn, &fn))
522 /* Declare void __cxa_free_exception (void *). */
523 fn = push_void_library_fn (fn, tree_cons (NULL_TREE, ptr_type_node,
527 return build_function_call (fn, tree_cons (NULL_TREE, ptr, NULL_TREE));
531 /* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
532 Called from build_throw via walk_tree_without_duplicates. */
535 wrap_cleanups_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
536 void *data ATTRIBUTE_UNUSED)
541 /* Don't walk into types. */
547 if (TREE_CODE (exp) != TARGET_EXPR)
550 cleanup = TARGET_EXPR_CLEANUP (exp);
553 cleanup = build1 (MUST_NOT_THROW_EXPR, void_type_node, cleanup);
554 TARGET_EXPR_CLEANUP (exp) = cleanup;
557 /* Keep iterating. */
561 /* Like stabilize_expr, but specifically for a thrown expression. When
562 throwing a temporary class object, we want to construct it directly into
563 the thrown exception, so we look past the TARGET_EXPR and stabilize the
564 arguments of the call instead.
566 The case where EXP is a call to a function returning a class is a bit of
567 a grey area in the standard; it's unclear whether or not it should be
568 allowed to throw. I'm going to say no, as that allows us to optimize
569 this case without worrying about deallocating the exception object if it
570 does. The alternatives would be either not optimizing this case, or
571 wrapping the initialization in a TRY_CATCH_EXPR to call do_free_exception
572 rather than in a MUST_NOT_THROW_EXPR, for this case only. */
575 stabilize_throw_expr (tree exp, tree *initp)
579 if (TREE_CODE (exp) == TARGET_EXPR
580 && TREE_CODE (TARGET_EXPR_INITIAL (exp)) == AGGR_INIT_EXPR
581 && flag_elide_constructors)
583 tree aggr_init = AGGR_INIT_EXPR_CHECK (TARGET_EXPR_INITIAL (exp));
584 tree args = TREE_OPERAND (aggr_init, 1);
585 tree newargs = NULL_TREE;
588 init_expr = void_zero_node;
589 for (; args; args = TREE_CHAIN (args))
591 tree arg = TREE_VALUE (args);
594 arg = stabilize_expr (arg, &arg_init_expr);
596 if (TREE_SIDE_EFFECTS (arg_init_expr))
597 init_expr = build (COMPOUND_EXPR, void_type_node, init_expr,
599 *p = tree_cons (NULL_TREE, arg, NULL_TREE);
600 p = &TREE_CHAIN (*p);
602 TREE_OPERAND (aggr_init, 1) = newargs;
606 exp = stabilize_expr (exp, &init_expr);
613 /* Build a throw expression. */
616 build_throw (tree exp)
620 if (exp == error_mark_node)
623 if (processing_template_decl)
624 return build_min (THROW_EXPR, void_type_node, exp);
626 if (exp == null_node)
627 warning ("throwing NULL, which has integral, not pointer type");
629 if (exp != NULL_TREE)
631 if (!is_admissible_throw_operand (exp))
632 return error_mark_node;
636 return error_mark_node;
638 if (exp && decl_is_java_type (TREE_TYPE (exp), 1))
640 tree fn = get_identifier ("_Jv_Throw");
641 if (!get_global_value_if_present (fn, &fn))
643 /* Declare void _Jv_Throw (void *). */
644 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
645 tmp = build_function_type (ptr_type_node, tmp);
646 fn = push_throw_library_fn (fn, tmp);
649 exp = build_function_call (fn, tree_cons (NULL_TREE, exp, NULL_TREE));
657 tree temp_expr, allocate_expr;
659 fn = get_identifier ("__cxa_throw");
660 if (!get_global_value_if_present (fn, &fn))
662 /* The CLEANUP_TYPE is the internal type of a destructor. */
663 if (cleanup_type == NULL_TREE)
665 tmp = void_list_node;
666 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
667 tmp = build_function_type (void_type_node, tmp);
668 cleanup_type = build_pointer_type (tmp);
671 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
672 /* ??? Second argument is supposed to be "std::type_info*". */
673 tmp = void_list_node;
674 tmp = tree_cons (NULL_TREE, cleanup_type, tmp);
675 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
676 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
677 tmp = build_function_type (void_type_node, tmp);
678 fn = push_throw_library_fn (fn, tmp);
681 /* throw expression */
682 /* First, decay it. */
683 exp = decay_conversion (exp);
685 /* OK, this is kind of wacky. The standard says that we call
686 terminate when the exception handling mechanism, after
687 completing evaluation of the expression to be thrown but
688 before the exception is caught (_except.throw_), calls a
689 user function that exits via an uncaught exception.
691 So we have to protect the actual initialization of the
692 exception object with terminate(), but evaluate the
693 expression first. Since there could be temps in the
694 expression, we need to handle that, too. We also expand
695 the call to __cxa_allocate_exception first (which doesn't
696 matter, since it can't throw). */
698 /* Pre-evaluate the thrown expression first, since if we allocated
699 the space first we would have to deal with cleaning it up if
700 evaluating this expression throws. */
701 exp = stabilize_throw_expr (exp, &temp_expr);
703 /* Allocate the space for the exception. */
704 allocate_expr = do_allocate_exception (TREE_TYPE (exp));
705 allocate_expr = get_target_expr (allocate_expr);
706 ptr = TARGET_EXPR_SLOT (allocate_expr);
707 object = build1 (NOP_EXPR, build_pointer_type (TREE_TYPE (exp)), ptr);
708 object = build_indirect_ref (object, NULL);
710 /* And initialize the exception object. */
711 exp = build_init (object, exp, LOOKUP_ONLYCONVERTING);
712 if (exp == error_mark_node)
714 error (" in thrown expression");
715 return error_mark_node;
718 exp = build1 (MUST_NOT_THROW_EXPR, void_type_node, exp);
719 /* Prepend the allocation. */
720 exp = build (COMPOUND_EXPR, TREE_TYPE (exp), allocate_expr, exp);
721 if (temp_expr != void_zero_node)
723 /* Prepend the calculation of the throw expression. Also, force
724 any cleanups from the expression to be evaluated here so that
725 we don't have to do them during unwinding. But first wrap
726 them in MUST_NOT_THROW_EXPR, since they are run after the
727 exception object is initialized. */
728 walk_tree_without_duplicates (&temp_expr, wrap_cleanups_r, 0);
729 exp = build (COMPOUND_EXPR, TREE_TYPE (exp), temp_expr, exp);
730 exp = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (exp), exp);
733 throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object)));
735 if (TYPE_HAS_DESTRUCTOR (TREE_TYPE (object)))
737 cleanup = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)),
738 complete_dtor_identifier, 0);
739 cleanup = BASELINK_FUNCTIONS (cleanup);
741 cxx_mark_addressable (cleanup);
742 /* Pretend it's a normal function. */
743 cleanup = build1 (ADDR_EXPR, cleanup_type, cleanup);
747 cleanup = build_int_2 (0, 0);
748 TREE_TYPE (cleanup) = cleanup_type;
751 tmp = tree_cons (NULL_TREE, cleanup, NULL_TREE);
752 tmp = tree_cons (NULL_TREE, throw_type, tmp);
753 tmp = tree_cons (NULL_TREE, ptr, tmp);
754 /* ??? Indicate that this function call throws throw_type. */
755 tmp = build_function_call (fn, tmp);
757 /* Tack on the initialization stuff. */
758 exp = build (COMPOUND_EXPR, TREE_TYPE (tmp), exp, tmp);
762 /* Rethrow current exception. */
764 tree fn = get_identifier ("__cxa_rethrow");
765 if (!get_global_value_if_present (fn, &fn))
767 /* Declare void __cxa_rethrow (void). */
768 fn = push_throw_library_fn
769 (fn, build_function_type (void_type_node, void_list_node));
772 /* ??? Indicate that this function call allows exceptions of the type
773 of the enclosing catch block (if known). */
774 exp = build_function_call (fn, NULL_TREE);
777 exp = build1 (THROW_EXPR, void_type_node, exp);
782 /* Make sure TYPE is complete, pointer to complete, reference to
783 complete, or pointer to cv void. Issue diagnostic on failure.
784 Return the zero on failure and nonzero on success. FROM can be
785 the expr or decl from whence TYPE came, if available. */
788 complete_ptr_ref_or_void_ptr_p (tree type, tree from)
792 /* Check complete. */
793 type = complete_type_or_else (type, from);
797 /* Or a pointer or ref to one, or cv void *. */
798 is_ptr = TREE_CODE (type) == POINTER_TYPE;
799 if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE)
801 tree core = TREE_TYPE (type);
803 if (is_ptr && VOID_TYPE_P (core))
805 else if (!complete_type_or_else (core, from))
811 /* Return truth-value if EXPRESSION is admissible in throw-expression,
812 i.e. if it is not of incomplete type or a pointer/reference to such
813 a type or of an abstract class type. */
816 is_admissible_throw_operand (tree expr)
818 tree type = TREE_TYPE (expr);
820 /* 15.1/4 [...] The type of the throw-expression shall not be an
821 incomplete type, or a pointer or a reference to an incomplete
822 type, other than void*, const void*, volatile void*, or
823 const volatile void*. Except for these restriction and the
824 restrictions on type matching mentioned in 15.3, the operand
825 of throw is treated exactly as a function argument in a call
826 (5.2.2) or the operand of a return statement. */
827 if (!complete_ptr_ref_or_void_ptr_p (type, expr))
830 /* 10.4/3 An abstract class shall not be used as a parameter type,
831 as a function return type or as type of an explicit
833 else if (CLASS_TYPE_P (type) && CLASSTYPE_PURE_VIRTUALS (type))
835 error ("expression '%E' of abstract class type '%T' cannot be used in throw-expression", expr, type);
842 /* Returns nonzero if FN is a declaration of a standard C library
843 function which is known not to throw.
845 [lib.res.on.exception.handling]: None of the functions from the
846 Standard C library shall report an error by throwing an
847 exception, unless it calls a program-supplied function that
848 throws an exception. */
853 nothrow_libfn_p (tree fn)
858 && DECL_EXTERNAL (fn)
859 && DECL_NAMESPACE_SCOPE_P (fn)
860 && DECL_EXTERN_C_P (fn))
863 /* Can't be a C library function. */
866 id = DECL_ASSEMBLER_NAME (fn);
867 return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id));
870 /* Returns nonzero if an exception of type FROM will be caught by a
871 handler for type TO, as per [except.handle]. */
874 can_convert_eh (tree to, tree from)
876 to = non_reference (to);
877 from = non_reference (from);
879 if (TREE_CODE (to) == POINTER_TYPE && TREE_CODE (from) == POINTER_TYPE)
882 from = TREE_TYPE (from);
884 if (! at_least_as_qualified_p (to, from))
887 if (TREE_CODE (to) == VOID_TYPE)
890 /* else fall through */
893 if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
894 && PUBLICLY_UNIQUELY_DERIVED_P (to, from))
900 /* Check whether any of HANDLERS are shadowed by another handler accepting
901 TYPE. Note that the shadowing may not be complete; even if an exception
902 of type B would be caught by a handler for A, there could be a derived
903 class C for which A is an ambiguous base but B is not, so the handler
904 for B would catch an exception of type C. */
907 check_handlers_1 (tree master, tree handlers)
909 tree type = TREE_TYPE (master);
912 for (handler = handlers; handler; handler = TREE_CHAIN (handler))
913 if (TREE_TYPE (handler)
914 && can_convert_eh (type, TREE_TYPE (handler)))
916 input_line = STMT_LINENO (handler);
917 warning ("exception of type `%T' will be caught",
918 TREE_TYPE (handler));
919 input_line = STMT_LINENO (master);
920 warning (" by earlier handler for `%T'", type);
925 /* Given a chain of HANDLERs, make sure that they're OK. */
928 check_handlers (tree handlers)
931 int save_line = input_line;
933 for (handler = handlers; handler; handler = TREE_CHAIN (handler))
935 if (TREE_CHAIN (handler) == NULL_TREE)
936 /* No more handlers; nothing to shadow. */;
937 else if (TREE_TYPE (handler) == NULL_TREE)
939 input_line = STMT_LINENO (handler);
941 ("`...' handler must be the last handler for its try block");
944 check_handlers_1 (handler, TREE_CHAIN (handler));
946 input_line = save_line;