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);
648 else if (really_overloaded_fn (fn))
650 error ("`%D' should never be overloaded", fn);
651 return error_mark_node;
\r
653 fn = OVL_CURRENT (fn);
654 exp = build_function_call (fn, tree_cons (NULL_TREE, exp, NULL_TREE));
662 tree temp_expr, allocate_expr;
664 fn = get_identifier ("__cxa_throw");
665 if (!get_global_value_if_present (fn, &fn))
667 /* The CLEANUP_TYPE is the internal type of a destructor. */
668 if (cleanup_type == NULL_TREE)
670 tmp = void_list_node;
671 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
672 tmp = build_function_type (void_type_node, tmp);
673 cleanup_type = build_pointer_type (tmp);
676 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
677 /* ??? Second argument is supposed to be "std::type_info*". */
678 tmp = void_list_node;
679 tmp = tree_cons (NULL_TREE, cleanup_type, tmp);
680 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
681 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
682 tmp = build_function_type (void_type_node, tmp);
683 fn = push_throw_library_fn (fn, tmp);
686 /* throw expression */
687 /* First, decay it. */
688 exp = decay_conversion (exp);
690 /* OK, this is kind of wacky. The standard says that we call
691 terminate when the exception handling mechanism, after
692 completing evaluation of the expression to be thrown but
693 before the exception is caught (_except.throw_), calls a
694 user function that exits via an uncaught exception.
696 So we have to protect the actual initialization of the
697 exception object with terminate(), but evaluate the
698 expression first. Since there could be temps in the
699 expression, we need to handle that, too. We also expand
700 the call to __cxa_allocate_exception first (which doesn't
701 matter, since it can't throw). */
703 /* Pre-evaluate the thrown expression first, since if we allocated
704 the space first we would have to deal with cleaning it up if
705 evaluating this expression throws. */
706 exp = stabilize_throw_expr (exp, &temp_expr);
708 /* Allocate the space for the exception. */
709 allocate_expr = do_allocate_exception (TREE_TYPE (exp));
710 allocate_expr = get_target_expr (allocate_expr);
711 ptr = TARGET_EXPR_SLOT (allocate_expr);
712 object = build1 (NOP_EXPR, build_pointer_type (TREE_TYPE (exp)), ptr);
713 object = build_indirect_ref (object, NULL);
715 /* And initialize the exception object. */
716 exp = build_init (object, exp, LOOKUP_ONLYCONVERTING);
717 if (exp == error_mark_node)
719 error (" in thrown expression");
720 return error_mark_node;
723 exp = build1 (MUST_NOT_THROW_EXPR, void_type_node, exp);
724 /* Prepend the allocation. */
725 exp = build (COMPOUND_EXPR, TREE_TYPE (exp), allocate_expr, exp);
726 if (temp_expr != void_zero_node)
728 /* Prepend the calculation of the throw expression. Also, force
729 any cleanups from the expression to be evaluated here so that
730 we don't have to do them during unwinding. But first wrap
731 them in MUST_NOT_THROW_EXPR, since they are run after the
732 exception object is initialized. */
733 walk_tree_without_duplicates (&temp_expr, wrap_cleanups_r, 0);
734 exp = build (COMPOUND_EXPR, TREE_TYPE (exp), temp_expr, exp);
735 exp = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (exp), exp);
738 throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object)));
740 if (TYPE_HAS_DESTRUCTOR (TREE_TYPE (object)))
742 cleanup = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)),
743 complete_dtor_identifier, 0);
744 cleanup = BASELINK_FUNCTIONS (cleanup);
746 cxx_mark_addressable (cleanup);
747 /* Pretend it's a normal function. */
748 cleanup = build1 (ADDR_EXPR, cleanup_type, cleanup);
752 cleanup = build_int_2 (0, 0);
753 TREE_TYPE (cleanup) = cleanup_type;
756 tmp = tree_cons (NULL_TREE, cleanup, NULL_TREE);
757 tmp = tree_cons (NULL_TREE, throw_type, tmp);
758 tmp = tree_cons (NULL_TREE, ptr, tmp);
759 /* ??? Indicate that this function call throws throw_type. */
760 tmp = build_function_call (fn, tmp);
762 /* Tack on the initialization stuff. */
763 exp = build (COMPOUND_EXPR, TREE_TYPE (tmp), exp, tmp);
767 /* Rethrow current exception. */
769 tree fn = get_identifier ("__cxa_rethrow");
770 if (!get_global_value_if_present (fn, &fn))
772 /* Declare void __cxa_rethrow (void). */
773 fn = push_throw_library_fn
774 (fn, build_function_type (void_type_node, void_list_node));
777 /* ??? Indicate that this function call allows exceptions of the type
778 of the enclosing catch block (if known). */
779 exp = build_function_call (fn, NULL_TREE);
782 exp = build1 (THROW_EXPR, void_type_node, exp);
787 /* Make sure TYPE is complete, pointer to complete, reference to
788 complete, or pointer to cv void. Issue diagnostic on failure.
789 Return the zero on failure and nonzero on success. FROM can be
790 the expr or decl from whence TYPE came, if available. */
793 complete_ptr_ref_or_void_ptr_p (tree type, tree from)
797 /* Check complete. */
798 type = complete_type_or_else (type, from);
802 /* Or a pointer or ref to one, or cv void *. */
803 is_ptr = TREE_CODE (type) == POINTER_TYPE;
804 if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE)
806 tree core = TREE_TYPE (type);
808 if (is_ptr && VOID_TYPE_P (core))
810 else if (!complete_type_or_else (core, from))
816 /* Return truth-value if EXPRESSION is admissible in throw-expression,
817 i.e. if it is not of incomplete type or a pointer/reference to such
818 a type or of an abstract class type. */
821 is_admissible_throw_operand (tree expr)
823 tree type = TREE_TYPE (expr);
825 /* 15.1/4 [...] The type of the throw-expression shall not be an
826 incomplete type, or a pointer or a reference to an incomplete
827 type, other than void*, const void*, volatile void*, or
828 const volatile void*. Except for these restriction and the
829 restrictions on type matching mentioned in 15.3, the operand
830 of throw is treated exactly as a function argument in a call
831 (5.2.2) or the operand of a return statement. */
832 if (!complete_ptr_ref_or_void_ptr_p (type, expr))
835 /* 10.4/3 An abstract class shall not be used as a parameter type,
836 as a function return type or as type of an explicit
838 else if (CLASS_TYPE_P (type) && CLASSTYPE_PURE_VIRTUALS (type))
840 error ("expression '%E' of abstract class type '%T' cannot be used in throw-expression", expr, type);
847 /* Returns nonzero if FN is a declaration of a standard C library
848 function which is known not to throw.
850 [lib.res.on.exception.handling]: None of the functions from the
851 Standard C library shall report an error by throwing an
852 exception, unless it calls a program-supplied function that
853 throws an exception. */
858 nothrow_libfn_p (tree fn)
863 && DECL_EXTERNAL (fn)
864 && DECL_NAMESPACE_SCOPE_P (fn)
865 && DECL_EXTERN_C_P (fn))
868 /* Can't be a C library function. */
871 id = DECL_ASSEMBLER_NAME (fn);
872 return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id));
875 /* Returns nonzero if an exception of type FROM will be caught by a
876 handler for type TO, as per [except.handle]. */
879 can_convert_eh (tree to, tree from)
881 to = non_reference (to);
882 from = non_reference (from);
884 if (TREE_CODE (to) == POINTER_TYPE && TREE_CODE (from) == POINTER_TYPE)
887 from = TREE_TYPE (from);
889 if (! at_least_as_qualified_p (to, from))
892 if (TREE_CODE (to) == VOID_TYPE)
895 /* Else fall through. */
898 if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
899 && PUBLICLY_UNIQUELY_DERIVED_P (to, from))
905 /* Check whether any of HANDLERS are shadowed by another handler accepting
906 TYPE. Note that the shadowing may not be complete; even if an exception
907 of type B would be caught by a handler for A, there could be a derived
908 class C for which A is an ambiguous base but B is not, so the handler
909 for B would catch an exception of type C. */
912 check_handlers_1 (tree master, tree handlers)
914 tree type = TREE_TYPE (master);
917 for (handler = handlers; handler; handler = TREE_CHAIN (handler))
918 if (TREE_TYPE (handler)
919 && can_convert_eh (type, TREE_TYPE (handler)))
921 input_line = STMT_LINENO (handler);
922 warning ("exception of type `%T' will be caught",
923 TREE_TYPE (handler));
924 input_line = STMT_LINENO (master);
925 warning (" by earlier handler for `%T'", type);
930 /* Given a chain of HANDLERs, make sure that they're OK. */
933 check_handlers (tree handlers)
936 int save_line = input_line;
938 for (handler = handlers; handler; handler = TREE_CHAIN (handler))
940 if (TREE_CHAIN (handler) == NULL_TREE)
941 /* No more handlers; nothing to shadow. */;
942 else if (TREE_TYPE (handler) == NULL_TREE)
944 input_line = STMT_LINENO (handler);
946 ("`...' handler must be the last handler for its try block");
949 check_handlers_1 (handler, TREE_CHAIN (handler));
951 input_line = save_line;