1 /* Handle exceptional things in C++.
2 Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005 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, 51 Franklin Street, Fifth Floor,
23 Boston, MA 02110-1301, USA. */
28 #include "coretypes.h"
39 #include "tree-inline.h"
40 #include "tree-iterator.h"
43 static void push_eh_cleanup (tree);
44 static tree prepare_eh_type (tree);
45 static tree build_eh_type_type (tree);
46 static tree do_begin_catch (void);
47 static int dtor_nothrow (tree);
48 static tree do_end_catch (tree);
49 static bool decl_is_java_type (tree decl, int err);
50 static void initialize_handler_parm (tree, tree);
51 static tree do_allocate_exception (tree);
52 static tree wrap_cleanups_r (tree *, int *, void *);
53 static int complete_ptr_ref_or_void_ptr_p (tree, tree);
54 static bool is_admissible_throw_operand (tree);
55 static int can_convert_eh (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");
83 if (targetm.arm_eabi_unwinder)
84 unwind_resume_libfunc = init_one_libfunc ("__cxa_end_cleanup");
86 default_init_unwind_resume_libfunc ();
88 lang_eh_runtime_type = build_eh_type_type;
89 lang_protect_cleanup_actions = &cp_protect_cleanup_actions;
92 /* Returns an expression to be executed if an unhandled exception is
93 propagated out of a cleanup region. */
96 cp_protect_cleanup_actions (void)
100 When the destruction of an object during stack unwinding exits
101 using an exception ... void terminate(); is called. */
102 return build_call_n (terminate_node, 0);
106 prepare_eh_type (tree type)
108 if (type == NULL_TREE)
110 if (type == error_mark_node)
111 return error_mark_node;
113 /* peel back references, so they match. */
114 type = non_reference (type);
116 /* Peel off cv qualifiers. */
117 type = TYPE_MAIN_VARIANT (type);
122 /* Return the type info for TYPE as used by EH machinery. */
124 eh_type_info (tree type)
128 if (type == NULL_TREE || type == error_mark_node)
131 if (decl_is_java_type (type, 0))
132 exp = build_java_class_ref (TREE_TYPE (type));
134 exp = get_tinfo_decl (type);
139 /* Build the address of a typeinfo decl for use in the runtime
140 matching field of the exception model. */
143 build_eh_type_type (tree type)
145 tree exp = eh_type_info (type);
152 return convert (ptr_type_node, build_address (exp));
158 return build0 (EXC_PTR_EXPR, ptr_type_node);
161 /* Build up a call to __cxa_get_exception_ptr so that we can build a
162 copy constructor for the thrown object. */
165 do_get_exception_ptr (void)
169 fn = get_identifier ("__cxa_get_exception_ptr");
170 if (!get_global_value_if_present (fn, &fn))
172 /* Declare void* __cxa_get_exception_ptr (void *). */
173 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
174 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
177 return build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
181 /* Build up a call to __cxa_begin_catch, to tell the runtime that the
182 exception has been handled. */
185 do_begin_catch (void)
189 fn = get_identifier ("__cxa_begin_catch");
190 if (!get_global_value_if_present (fn, &fn))
192 /* Declare void* __cxa_begin_catch (void *). */
193 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
194 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
197 return build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
201 /* Returns nonzero if cleaning up an exception of type TYPE (which can be
202 NULL_TREE for a ... handler) will not throw an exception. */
205 dtor_nothrow (tree type)
207 if (type == NULL_TREE)
210 if (!CLASS_TYPE_P (type))
213 if (CLASSTYPE_LAZY_DESTRUCTOR (type))
214 lazily_declare_fn (sfk_destructor, type);
216 return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type));
219 /* Build up a call to __cxa_end_catch, to destroy the exception object
220 for the current catch block if no others are currently using it. */
223 do_end_catch (tree type)
227 fn = get_identifier ("__cxa_end_catch");
228 if (!get_global_value_if_present (fn, &fn))
230 /* Declare void __cxa_end_catch (). */
231 fn = push_void_library_fn (fn, void_list_node);
232 /* This can throw if the destructor for the exception throws. */
233 TREE_NOTHROW (fn) = 0;
236 cleanup = build_function_call (fn, NULL_TREE);
237 TREE_NOTHROW (cleanup) = dtor_nothrow (type);
242 /* This routine creates the cleanup for the current exception. */
245 push_eh_cleanup (tree type)
247 finish_decl_cleanup (NULL_TREE, do_end_catch (type));
250 /* Return nonzero value if DECL is a Java type suitable for catch or
254 decl_is_java_type (tree decl, int err)
256 bool r = (TREE_CODE (decl) == POINTER_TYPE
257 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
258 && TYPE_FOR_JAVA (TREE_TYPE (decl)));
262 if (TREE_CODE (decl) == REFERENCE_TYPE
263 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
264 && TYPE_FOR_JAVA (TREE_TYPE (decl)))
266 /* Can't throw a reference. */
267 error ("type %qT is disallowed in Java %<throw%> or %<catch%>",
274 = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));
276 if (jthrow_node == NULL_TREE)
278 ("call to Java %<catch%> or %<throw%> with %<jthrowable%> undefined");
280 jthrow_node = TREE_TYPE (TREE_TYPE (jthrow_node));
282 if (! DERIVED_FROM_P (jthrow_node, TREE_TYPE (decl)))
284 /* Thrown object must be a Throwable. */
285 error ("type %qT is not derived from %<java::lang::Throwable%>",
294 /* Select the personality routine to be used for exception handling,
295 or issue an error if we need two different ones in the same
297 ??? At present eh_personality_libfunc is set to
298 __gxx_personality_(sj|v)0 in init_exception_processing - should it
299 be done here instead? */
301 choose_personality_routine (enum languages lang)
316 if (lang != lang_cplusplus)
321 if (lang != lang_java)
326 ; /* Proceed to language selection. */
337 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
338 ? "__gcj_personality_sj0"
339 : "__gcj_personality_v0");
348 error ("mixing C++ and Java catches in a single translation unit");
352 /* Initialize the catch parameter DECL. */
355 initialize_handler_parm (tree decl, tree exp)
360 /* Make sure we mark the catch param as used, otherwise we'll get a
361 warning about an unused ((anonymous)). */
362 TREE_USED (decl) = 1;
364 /* Figure out the type that the initializer is. Pointers are returned
365 adjusted by value from __cxa_begin_catch. Others are returned by
367 init_type = TREE_TYPE (decl);
368 if (!POINTER_TYPE_P (init_type))
369 init_type = build_reference_type (init_type);
371 choose_personality_routine (decl_is_java_type (init_type, 0)
372 ? lang_java : lang_cplusplus);
374 /* Since pointers are passed by value, initialize a reference to
375 pointer catch parm with the address of the temporary. */
376 if (TREE_CODE (init_type) == REFERENCE_TYPE
377 && TYPE_PTR_P (TREE_TYPE (init_type)))
378 exp = build_unary_op (ADDR_EXPR, exp, 1);
380 exp = ocp_convert (init_type, exp, CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
382 init = convert_from_reference (exp);
384 /* If the constructor for the catch parm exits via an exception, we
385 must call terminate. See eh23.C. */
386 if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
388 /* Generate the copy constructor call directly so we can wrap it.
389 See also expand_default_init. */
390 init = ocp_convert (TREE_TYPE (decl), init,
391 CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
392 init = build1 (MUST_NOT_THROW_EXPR, TREE_TYPE (init), init);
395 decl = pushdecl (decl);
397 start_decl_1 (decl, true);
398 cp_finish_decl (decl, init, /*init_const_expr_p=*/false, NULL_TREE,
399 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
402 /* Call this to start a catch block. DECL is the catch parameter. */
405 expand_start_catch_block (tree decl)
413 /* Make sure this declaration is reasonable. */
414 if (decl && !complete_ptr_ref_or_void_ptr_p (TREE_TYPE (decl), NULL_TREE))
415 decl = error_mark_node;
418 type = prepare_eh_type (TREE_TYPE (decl));
422 if (decl && decl_is_java_type (type, 1))
424 /* Java only passes object via pointer and doesn't require
425 adjusting. The java object is immediately before the
426 generic exception header. */
427 exp = build_exc_ptr ();
428 exp = build1 (NOP_EXPR, build_pointer_type (type), exp);
429 exp = build2 (MINUS_EXPR, TREE_TYPE (exp), exp,
430 TYPE_SIZE_UNIT (TREE_TYPE (exp)));
431 exp = build_indirect_ref (exp, NULL);
432 initialize_handler_parm (decl, exp);
436 /* Call __cxa_end_catch at the end of processing the exception. */
437 push_eh_cleanup (type);
439 /* If there's no decl at all, then all we need to do is make sure
440 to tell the runtime that we've begun handling the exception. */
441 if (decl == NULL || decl == error_mark_node)
442 finish_expr_stmt (do_begin_catch ());
444 /* If the C++ object needs constructing, we need to do that before
445 calling __cxa_begin_catch, so that std::uncaught_exception gets
446 the right value during the copy constructor. */
447 else if (flag_use_cxa_get_exception_ptr
448 && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
450 exp = do_get_exception_ptr ();
451 initialize_handler_parm (decl, exp);
452 finish_expr_stmt (do_begin_catch ());
455 /* Otherwise the type uses a bitwise copy, and we don't have to worry
456 about the value of std::uncaught_exception and therefore can do the
457 copy with the return value of __cxa_end_catch instead. */
460 tree init = do_begin_catch ();
461 tree init_type = type;
463 /* Pointers are passed by values, everything else by reference. */
464 if (!TYPE_PTR_P (type))
465 init_type = build_pointer_type (type);
466 if (init_type != TREE_TYPE (init))
467 init = build1 (NOP_EXPR, init_type, init);
468 exp = create_temporary_var (init_type);
469 DECL_REGISTER (exp) = 1;
470 cp_finish_decl (exp, init, /*init_const_expr=*/false,
471 NULL_TREE, LOOKUP_ONLYCONVERTING);
472 initialize_handler_parm (decl, exp);
479 /* Call this to end a catch block. Its responsible for emitting the
480 code to handle jumping back to the correct place, and for emitting
481 the label to jump to if this catch block didn't match. */
484 expand_end_catch_block (void)
489 /* The exception being handled is rethrown if control reaches the end of
490 a handler of the function-try-block of a constructor or destructor. */
491 if (in_function_try_handler
492 && (DECL_CONSTRUCTOR_P (current_function_decl)
493 || DECL_DESTRUCTOR_P (current_function_decl)))
494 finish_expr_stmt (build_throw (NULL_TREE));
498 begin_eh_spec_block (void)
500 tree r = build_stmt (EH_SPEC_BLOCK, NULL_TREE, NULL_TREE);
502 EH_SPEC_STMTS (r) = push_stmt_list ();
507 finish_eh_spec_block (tree raw_raises, tree eh_spec_block)
511 EH_SPEC_STMTS (eh_spec_block) = pop_stmt_list (EH_SPEC_STMTS (eh_spec_block));
513 /* Strip cv quals, etc, from the specification types. */
514 for (raises = NULL_TREE;
515 raw_raises && TREE_VALUE (raw_raises);
516 raw_raises = TREE_CHAIN (raw_raises))
518 tree type = prepare_eh_type (TREE_VALUE (raw_raises));
519 tree tinfo = eh_type_info (type);
522 raises = tree_cons (NULL_TREE, type, raises);
525 EH_SPEC_RAISES (eh_spec_block) = raises;
528 /* Return a pointer to a buffer for an exception object of type TYPE. */
531 do_allocate_exception (tree type)
535 fn = get_identifier ("__cxa_allocate_exception");
536 if (!get_global_value_if_present (fn, &fn))
538 /* Declare void *__cxa_allocate_exception(size_t). */
539 tree tmp = tree_cons (NULL_TREE, size_type_node, void_list_node);
540 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
543 return build_function_call (fn, tree_cons (NULL_TREE, size_in_bytes (type),
547 /* Call __cxa_free_exception from a cleanup. This is never invoked
548 directly, but see the comment for stabilize_throw_expr. */
551 do_free_exception (tree ptr)
555 fn = get_identifier ("__cxa_free_exception");
556 if (!get_global_value_if_present (fn, &fn))
558 /* Declare void __cxa_free_exception (void *). */
559 fn = push_void_library_fn (fn, tree_cons (NULL_TREE, ptr_type_node,
563 return build_function_call (fn, tree_cons (NULL_TREE, ptr, NULL_TREE));
566 /* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
567 Called from build_throw via walk_tree_without_duplicates. */
570 wrap_cleanups_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
571 void *data ATTRIBUTE_UNUSED)
576 /* Don't walk into types. */
582 if (TREE_CODE (exp) != TARGET_EXPR)
585 cleanup = TARGET_EXPR_CLEANUP (exp);
588 cleanup = build1 (MUST_NOT_THROW_EXPR, void_type_node, cleanup);
589 TARGET_EXPR_CLEANUP (exp) = cleanup;
592 /* Keep iterating. */
596 /* Build a throw expression. */
599 build_throw (tree exp)
603 if (exp == error_mark_node)
606 if (processing_template_decl)
609 current_function_returns_abnormally = 1;
610 return build_min (THROW_EXPR, void_type_node, exp);
613 if (exp == null_node)
614 warning (0, "throwing NULL, which has integral, not pointer type");
616 if (exp != NULL_TREE)
618 if (!is_admissible_throw_operand (exp))
619 return error_mark_node;
623 return error_mark_node;
625 if (exp && decl_is_java_type (TREE_TYPE (exp), 1))
627 tree fn = get_identifier ("_Jv_Throw");
628 if (!get_global_value_if_present (fn, &fn))
630 /* Declare void _Jv_Throw (void *). */
631 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
632 tmp = build_function_type (ptr_type_node, tmp);
633 fn = push_throw_library_fn (fn, tmp);
635 else if (really_overloaded_fn (fn))
637 error ("%qD should never be overloaded", fn);
638 return error_mark_node;
640 fn = OVL_CURRENT (fn);
641 exp = build_function_call (fn, tree_cons (NULL_TREE, exp, NULL_TREE));
650 tree temp_expr, allocate_expr;
653 /* The CLEANUP_TYPE is the internal type of a destructor. */
656 tmp = void_list_node;
657 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
658 tmp = build_function_type (void_type_node, tmp);
659 cleanup_type = build_pointer_type (tmp);
662 fn = get_identifier ("__cxa_throw");
663 if (!get_global_value_if_present (fn, &fn))
665 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
666 /* ??? Second argument is supposed to be "std::type_info*". */
667 tmp = void_list_node;
668 tmp = tree_cons (NULL_TREE, cleanup_type, tmp);
669 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
670 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
671 tmp = build_function_type (void_type_node, tmp);
672 fn = push_throw_library_fn (fn, tmp);
677 A throw-expression initializes a temporary object, the type
678 of which is determined by removing any top-level
679 cv-qualifiers from the static type of the operand of throw
680 and adjusting the type from "array of T" or "function return
681 T" to "pointer to T" or "pointer to function returning T"
683 temp_type = is_bitfield_expr_with_lowered_type (exp);
685 temp_type = type_decays_to (TYPE_MAIN_VARIANT (TREE_TYPE (exp)));
687 /* OK, this is kind of wacky. The standard says that we call
688 terminate when the exception handling mechanism, after
689 completing evaluation of the expression to be thrown but
690 before the exception is caught (_except.throw_), calls a
691 user function that exits via an uncaught exception.
693 So we have to protect the actual initialization of the
694 exception object with terminate(), but evaluate the
695 expression first. Since there could be temps in the
696 expression, we need to handle that, too. We also expand
697 the call to __cxa_allocate_exception first (which doesn't
698 matter, since it can't throw). */
700 /* Allocate the space for the exception. */
701 allocate_expr = do_allocate_exception (temp_type);
702 allocate_expr = get_target_expr (allocate_expr);
703 ptr = TARGET_EXPR_SLOT (allocate_expr);
704 object = build_nop (build_pointer_type (temp_type), ptr);
705 object = build_indirect_ref (object, NULL);
707 elided = (TREE_CODE (exp) == TARGET_EXPR);
709 /* And initialize the exception object. */
710 if (CLASS_TYPE_P (temp_type))
712 int flags = LOOKUP_NORMAL | LOOKUP_ONLYCONVERTING;
714 /* Under C++0x [12.8/16 class.copy], a thrown lvalue is sometimes
715 treated as an rvalue for the purposes of overload resolution
716 to favor move constructors over copy constructors. */
717 if (/* Must be a local, automatic variable. */
718 TREE_CODE (exp) == VAR_DECL
719 && DECL_CONTEXT (exp) == current_function_decl
720 && ! TREE_STATIC (exp)
721 /* The variable must not have the `volatile' qualifier. */
722 && !(cp_type_quals (TREE_TYPE (exp)) & TYPE_QUAL_VOLATILE))
723 flags = flags | LOOKUP_PREFER_RVALUE;
725 /* Call the copy constructor. */
726 exp = (build_special_member_call
727 (object, complete_ctor_identifier,
728 build_tree_list (NULL_TREE, exp),
731 if (exp == error_mark_node)
733 error (" in thrown expression");
734 return error_mark_node;
738 exp = build2 (INIT_EXPR, temp_type, object,
739 decay_conversion (exp));
741 /* Pre-evaluate the thrown expression first, since if we allocated
742 the space first we would have to deal with cleaning it up if
743 evaluating this expression throws.
745 The case where EXP the initializer is a cast or a function
746 returning a class is a bit of a grey area in the standard; it's
747 unclear whether or not it should be allowed to throw. We used to
748 say no, as that allowed us to optimize this case without worrying
749 about deallocating the exception object if it does. But that
750 conflicted with expectations (PR 13944) and the EDG compiler; now
751 we wrap the initialization in a TRY_CATCH_EXPR to call
752 do_free_exception rather than in a MUST_NOT_THROW_EXPR, for this
755 BUT: Issue 475 may do away with this inconsistency by removing the
756 terminate() in this situation.
758 Note that we don't check the return value from stabilize_init
759 because it will only return false in cases where elided is true,
760 and therefore we don't need to work around the failure to
762 temp_expr = NULL_TREE;
763 stabilize_init (exp, &temp_expr);
765 /* Wrap the initialization in a CLEANUP_POINT_EXPR so that cleanups
766 for temporaries within the initialization are run before the one
767 for the exception object, preserving LIFO order. */
768 exp = build1 (CLEANUP_POINT_EXPR, void_type_node, exp);
771 exp = build2 (TRY_CATCH_EXPR, void_type_node, exp,
772 do_free_exception (ptr));
774 exp = build1 (MUST_NOT_THROW_EXPR, void_type_node, exp);
776 /* Prepend the allocation. */
777 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), allocate_expr, exp);
780 /* Prepend the calculation of the throw expression. Also, force
781 any cleanups from the expression to be evaluated here so that
782 we don't have to do them during unwinding. But first wrap
783 them in MUST_NOT_THROW_EXPR, since they are run after the
784 exception object is initialized. */
785 walk_tree_without_duplicates (&temp_expr, wrap_cleanups_r, 0);
786 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), temp_expr, exp);
787 exp = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (exp), exp);
790 throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object)));
792 if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (object)))
794 cleanup = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)),
795 complete_dtor_identifier, 0);
796 cleanup = BASELINK_FUNCTIONS (cleanup);
798 cxx_mark_addressable (cleanup);
799 /* Pretend it's a normal function. */
800 cleanup = build1 (ADDR_EXPR, cleanup_type, cleanup);
803 cleanup = build_int_cst (cleanup_type, 0);
805 tmp = tree_cons (NULL_TREE, cleanup, NULL_TREE);
806 tmp = tree_cons (NULL_TREE, throw_type, tmp);
807 tmp = tree_cons (NULL_TREE, ptr, tmp);
808 /* ??? Indicate that this function call throws throw_type. */
809 tmp = build_function_call (fn, tmp);
811 /* Tack on the initialization stuff. */
812 exp = build2 (COMPOUND_EXPR, TREE_TYPE (tmp), exp, tmp);
816 /* Rethrow current exception. */
818 tree fn = get_identifier ("__cxa_rethrow");
819 if (!get_global_value_if_present (fn, &fn))
821 /* Declare void __cxa_rethrow (void). */
822 fn = push_throw_library_fn
823 (fn, build_function_type (void_type_node, void_list_node));
826 /* ??? Indicate that this function call allows exceptions of the type
827 of the enclosing catch block (if known). */
828 exp = build_function_call (fn, NULL_TREE);
831 exp = build1 (THROW_EXPR, void_type_node, exp);
836 /* Make sure TYPE is complete, pointer to complete, reference to
837 complete, or pointer to cv void. Issue diagnostic on failure.
838 Return the zero on failure and nonzero on success. FROM can be
839 the expr or decl from whence TYPE came, if available. */
842 complete_ptr_ref_or_void_ptr_p (tree type, tree from)
846 /* Check complete. */
847 type = complete_type_or_else (type, from);
851 /* Or a pointer or ref to one, or cv void *. */
852 is_ptr = TREE_CODE (type) == POINTER_TYPE;
853 if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE)
855 tree core = TREE_TYPE (type);
857 if (is_ptr && VOID_TYPE_P (core))
859 else if (!complete_type_or_else (core, from))
865 /* Return truth-value if EXPRESSION is admissible in throw-expression,
866 i.e. if it is not of incomplete type or a pointer/reference to such
867 a type or of an abstract class type. */
870 is_admissible_throw_operand (tree expr)
872 tree type = TREE_TYPE (expr);
874 /* 15.1/4 [...] The type of the throw-expression shall not be an
875 incomplete type, or a pointer or a reference to an incomplete
876 type, other than void*, const void*, volatile void*, or
877 const volatile void*. Except for these restriction and the
878 restrictions on type matching mentioned in 15.3, the operand
879 of throw is treated exactly as a function argument in a call
880 (5.2.2) or the operand of a return statement. */
881 if (!complete_ptr_ref_or_void_ptr_p (type, expr))
884 /* 10.4/3 An abstract class shall not be used as a parameter type,
885 as a function return type or as type of an explicit
887 else if (CLASS_TYPE_P (type) && CLASSTYPE_PURE_VIRTUALS (type))
889 error ("expression %qE of abstract class type %qT cannot "
890 "be used in throw-expression", expr, type);
897 /* Returns nonzero if FN is a declaration of a standard C library
898 function which is known not to throw.
900 [lib.res.on.exception.handling]: None of the functions from the
901 Standard C library shall report an error by throwing an
902 exception, unless it calls a program-supplied function that
903 throws an exception. */
908 nothrow_libfn_p (tree fn)
913 && DECL_EXTERNAL (fn)
914 && DECL_NAMESPACE_SCOPE_P (fn)
915 && DECL_EXTERN_C_P (fn))
918 /* Can't be a C library function. */
921 /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME
922 unless the system headers are playing rename tricks, and if
923 they are, we don't want to be confused by them. */
925 return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id));
928 /* Returns nonzero if an exception of type FROM will be caught by a
929 handler for type TO, as per [except.handle]. */
932 can_convert_eh (tree to, tree from)
934 to = non_reference (to);
935 from = non_reference (from);
937 if (TREE_CODE (to) == POINTER_TYPE && TREE_CODE (from) == POINTER_TYPE)
940 from = TREE_TYPE (from);
942 if (! at_least_as_qualified_p (to, from))
945 if (TREE_CODE (to) == VOID_TYPE)
948 /* Else fall through. */
951 if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
952 && PUBLICLY_UNIQUELY_DERIVED_P (to, from))
958 /* Check whether any of the handlers in I are shadowed by another handler
959 accepting TYPE. Note that the shadowing may not be complete; even if
960 an exception of type B would be caught by a handler for A, there could
961 be a derived class C for which A is an ambiguous base but B is not, so
962 the handler for B would catch an exception of type C. */
965 check_handlers_1 (tree master, tree_stmt_iterator i)
967 tree type = TREE_TYPE (master);
969 for (; !tsi_end_p (i); tsi_next (&i))
971 tree handler = tsi_stmt (i);
972 if (TREE_TYPE (handler) && can_convert_eh (type, TREE_TYPE (handler)))
974 warning (0, "%Hexception of type %qT will be caught",
975 EXPR_LOCUS (handler), TREE_TYPE (handler));
976 warning (0, "%H by earlier handler for %qT",
977 EXPR_LOCUS (master), type);
983 /* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK. */
986 check_handlers (tree handlers)
988 tree_stmt_iterator i;
990 /* If we don't have a STATEMENT_LIST, then we've just got one
991 handler, and thus nothing to warn about. */
992 if (TREE_CODE (handlers) != STATEMENT_LIST)
995 i = tsi_start (handlers);
999 tree handler = tsi_stmt (i);
1002 /* No more handlers; nothing to shadow. */
1005 if (TREE_TYPE (handler) == NULL_TREE)
1006 pedwarn ("%H%<...%> handler must be the last handler for"
1007 " its try block", EXPR_LOCUS (handler));
1009 check_handlers_1 (handler, i);