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, 2007, 2008, 2009
4 Free Software Foundation, Inc.
5 Contributed by Michael Tiemann <tiemann@cygnus.com>
6 Rewritten by Mike Stump <mrs@cygnus.com>, based upon an
7 initial re-implementation courtesy Tad Hunt.
9 This file is part of GCC.
11 GCC is free software; you can redistribute it and/or modify
12 it under the terms of the GNU General Public License as published by
13 the Free Software Foundation; either version 3, or (at your option)
16 GCC is distributed in the hope that it will be useful,
17 but WITHOUT ANY WARRANTY; without even the implied warranty of
18 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 GNU General Public License for more details.
21 You should have received a copy of the GNU General Public License
22 along with GCC; see the file COPYING3. If not see
23 <http://www.gnu.org/licenses/>. */
28 #include "coretypes.h"
39 #include "tree-inline.h"
40 #include "tree-iterator.h"
44 static void push_eh_cleanup (tree);
45 static tree prepare_eh_type (tree);
46 static tree build_eh_type_type (tree);
47 static tree do_begin_catch (void);
48 static int dtor_nothrow (tree);
49 static tree do_end_catch (tree);
50 static bool decl_is_java_type (tree decl, int err);
51 static void initialize_handler_parm (tree, tree);
52 static tree do_allocate_exception (tree);
53 static tree wrap_cleanups_r (tree *, int *, void *);
54 static int complete_ptr_ref_or_void_ptr_p (tree, tree);
55 static bool is_admissible_throw_operand (tree);
56 static int can_convert_eh (tree, tree);
57 static gimple cp_protect_cleanup_actions (void);
59 /* Sets up all the global eh stuff that needs to be initialized at the
60 start of compilation. */
63 init_exception_processing (void)
67 /* void std::terminate (); */
68 push_namespace (std_identifier);
69 tmp = build_function_type (void_type_node, void_list_node);
70 terminate_node = build_cp_library_fn_ptr ("terminate", tmp);
71 TREE_THIS_VOLATILE (terminate_node) = 1;
72 TREE_NOTHROW (terminate_node) = 1;
75 /* void __cxa_call_unexpected(void *); */
76 tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
77 tmp = build_function_type (void_type_node, tmp);
79 = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp);
81 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
82 ? "__gxx_personality_sj0"
83 : "__gxx_personality_v0");
84 if (targetm.arm_eabi_unwinder)
85 unwind_resume_libfunc = init_one_libfunc ("__cxa_end_cleanup");
87 default_init_unwind_resume_libfunc ();
89 lang_eh_runtime_type = build_eh_type_type;
90 lang_protect_cleanup_actions = &cp_protect_cleanup_actions;
93 /* Returns an expression to be executed if an unhandled exception is
94 propagated out of a cleanup region. */
97 cp_protect_cleanup_actions (void)
101 When the destruction of an object during stack unwinding exits
102 using an exception ... void terminate(); is called. */
103 return gimple_build_call (terminate_node, 0);
107 prepare_eh_type (tree type)
109 if (type == NULL_TREE)
111 if (type == error_mark_node)
112 return error_mark_node;
114 /* peel back references, so they match. */
115 type = non_reference (type);
117 /* Peel off cv qualifiers. */
118 type = TYPE_MAIN_VARIANT (type);
120 /* Functions and arrays decay to pointers. */
121 type = type_decays_to (type);
126 /* Return the type info for TYPE as used by EH machinery. */
128 eh_type_info (tree type)
132 if (type == NULL_TREE || type == error_mark_node)
135 if (decl_is_java_type (type, 0))
136 exp = build_java_class_ref (TREE_TYPE (type));
138 exp = get_tinfo_decl (type);
143 /* Build the address of a typeinfo decl for use in the runtime
144 matching field of the exception model. */
147 build_eh_type_type (tree type)
149 tree exp = eh_type_info (type);
156 return convert (ptr_type_node, build_address (exp));
162 return build0 (EXC_PTR_EXPR, ptr_type_node);
165 /* Declare a function NAME, returning RETURN_TYPE, taking a single
166 parameter PARM_TYPE, with an empty exception specification.
168 Note that the C++ ABI document does not have a throw-specifier on
169 the routines declared below via this function. The declarations
170 are consistent with the actual implementations in libsupc++. */
173 declare_nothrow_library_fn (tree name, tree return_type, tree parm_type)
175 tree tmp = tree_cons (NULL_TREE, parm_type, void_list_node);
176 return push_library_fn (name, build_function_type (return_type, tmp),
180 /* Build up a call to __cxa_get_exception_ptr so that we can build a
181 copy constructor for the thrown object. */
184 do_get_exception_ptr (void)
188 fn = get_identifier ("__cxa_get_exception_ptr");
189 if (!get_global_value_if_present (fn, &fn))
191 /* Declare void* __cxa_get_exception_ptr (void *) throw(). */
192 fn = declare_nothrow_library_fn (fn, ptr_type_node, ptr_type_node);
195 return cp_build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
197 tf_warning_or_error);
200 /* Build up a call to __cxa_begin_catch, to tell the runtime that the
201 exception has been handled. */
204 do_begin_catch (void)
208 fn = get_identifier ("__cxa_begin_catch");
209 if (!get_global_value_if_present (fn, &fn))
211 /* Declare void* __cxa_begin_catch (void *) throw(). */
212 fn = declare_nothrow_library_fn (fn, ptr_type_node, ptr_type_node);
215 return cp_build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
217 tf_warning_or_error);
220 /* Returns nonzero if cleaning up an exception of type TYPE (which can be
221 NULL_TREE for a ... handler) will not throw an exception. */
224 dtor_nothrow (tree type)
226 if (type == NULL_TREE)
229 if (!CLASS_TYPE_P (type))
232 if (CLASSTYPE_LAZY_DESTRUCTOR (type))
233 lazily_declare_fn (sfk_destructor, type);
235 return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type));
238 /* Build up a call to __cxa_end_catch, to destroy the exception object
239 for the current catch block if no others are currently using it. */
242 do_end_catch (tree type)
246 fn = get_identifier ("__cxa_end_catch");
247 if (!get_global_value_if_present (fn, &fn))
249 /* Declare void __cxa_end_catch (). */
250 fn = push_void_library_fn (fn, void_list_node);
251 /* This can throw if the destructor for the exception throws. */
252 TREE_NOTHROW (fn) = 0;
255 cleanup = cp_build_function_call (fn, NULL_TREE, tf_warning_or_error);
256 TREE_NOTHROW (cleanup) = dtor_nothrow (type);
261 /* This routine creates the cleanup for the current exception. */
264 push_eh_cleanup (tree type)
266 finish_decl_cleanup (NULL_TREE, do_end_catch (type));
269 /* Return nonzero value if DECL is a Java type suitable for catch or
273 decl_is_java_type (tree decl, int err)
275 bool r = (TREE_CODE (decl) == POINTER_TYPE
276 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
277 && TYPE_FOR_JAVA (TREE_TYPE (decl)));
281 if (TREE_CODE (decl) == REFERENCE_TYPE
282 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
283 && TYPE_FOR_JAVA (TREE_TYPE (decl)))
285 /* Can't throw a reference. */
286 error ("type %qT is disallowed in Java %<throw%> or %<catch%>",
293 = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));
295 if (jthrow_node == NULL_TREE)
297 ("call to Java %<catch%> or %<throw%> with %<jthrowable%> undefined");
299 jthrow_node = TREE_TYPE (TREE_TYPE (jthrow_node));
301 if (! DERIVED_FROM_P (jthrow_node, TREE_TYPE (decl)))
303 /* Thrown object must be a Throwable. */
304 error ("type %qT is not derived from %<java::lang::Throwable%>",
313 /* Select the personality routine to be used for exception handling,
314 or issue an error if we need two different ones in the same
316 ??? At present eh_personality_libfunc is set to
317 __gxx_personality_(sj|v)0 in init_exception_processing - should it
318 be done here instead? */
320 choose_personality_routine (enum languages lang)
335 if (lang != lang_cplusplus)
340 if (lang != lang_java)
345 ; /* Proceed to language selection. */
356 terminate_node = built_in_decls [BUILT_IN_ABORT];
357 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
358 ? "__gcj_personality_sj0"
359 : "__gcj_personality_v0");
368 error ("mixing C++ and Java catches in a single translation unit");
372 /* Initialize the catch parameter DECL. */
375 initialize_handler_parm (tree decl, tree exp)
380 /* Make sure we mark the catch param as used, otherwise we'll get a
381 warning about an unused ((anonymous)). */
382 TREE_USED (decl) = 1;
384 /* Figure out the type that the initializer is. Pointers are returned
385 adjusted by value from __cxa_begin_catch. Others are returned by
387 init_type = TREE_TYPE (decl);
388 if (!POINTER_TYPE_P (init_type))
389 init_type = build_reference_type (init_type);
391 choose_personality_routine (decl_is_java_type (init_type, 0)
392 ? lang_java : lang_cplusplus);
394 /* Since pointers are passed by value, initialize a reference to
395 pointer catch parm with the address of the temporary. */
396 if (TREE_CODE (init_type) == REFERENCE_TYPE
397 && TYPE_PTR_P (TREE_TYPE (init_type)))
398 exp = cp_build_unary_op (ADDR_EXPR, exp, 1, tf_warning_or_error);
400 exp = ocp_convert (init_type, exp, CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
402 init = convert_from_reference (exp);
404 /* If the constructor for the catch parm exits via an exception, we
405 must call terminate. See eh23.C. */
406 if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
408 /* Generate the copy constructor call directly so we can wrap it.
409 See also expand_default_init. */
410 init = ocp_convert (TREE_TYPE (decl), init,
411 CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
412 /* Force cleanups now to avoid nesting problems with the
413 MUST_NOT_THROW_EXPR. */
414 init = fold_build_cleanup_point_expr (TREE_TYPE (init), init);
415 init = build1 (MUST_NOT_THROW_EXPR, TREE_TYPE (init), init);
418 decl = pushdecl (decl);
420 start_decl_1 (decl, true);
421 cp_finish_decl (decl, init, /*init_const_expr_p=*/false, NULL_TREE,
422 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
425 /* Call this to start a catch block. DECL is the catch parameter. */
428 expand_start_catch_block (tree decl)
436 /* Make sure this declaration is reasonable. */
437 if (decl && !complete_ptr_ref_or_void_ptr_p (TREE_TYPE (decl), NULL_TREE))
438 decl = error_mark_node;
441 type = prepare_eh_type (TREE_TYPE (decl));
445 if (decl && decl_is_java_type (type, 1))
447 /* Java only passes object via pointer and doesn't require
448 adjusting. The java object is immediately before the
449 generic exception header. */
450 exp = build_exc_ptr ();
451 exp = build1 (NOP_EXPR, build_pointer_type (type), exp);
452 exp = build2 (POINTER_PLUS_EXPR, TREE_TYPE (exp), exp,
453 fold_build1 (NEGATE_EXPR, sizetype,
454 TYPE_SIZE_UNIT (TREE_TYPE (exp))));
455 exp = cp_build_indirect_ref (exp, NULL, tf_warning_or_error);
456 initialize_handler_parm (decl, exp);
460 /* Call __cxa_end_catch at the end of processing the exception. */
461 push_eh_cleanup (type);
463 /* If there's no decl at all, then all we need to do is make sure
464 to tell the runtime that we've begun handling the exception. */
465 if (decl == NULL || decl == error_mark_node)
466 finish_expr_stmt (do_begin_catch ());
468 /* If the C++ object needs constructing, we need to do that before
469 calling __cxa_begin_catch, so that std::uncaught_exception gets
470 the right value during the copy constructor. */
471 else if (flag_use_cxa_get_exception_ptr
472 && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
474 exp = do_get_exception_ptr ();
475 initialize_handler_parm (decl, exp);
476 finish_expr_stmt (do_begin_catch ());
479 /* Otherwise the type uses a bitwise copy, and we don't have to worry
480 about the value of std::uncaught_exception and therefore can do the
481 copy with the return value of __cxa_end_catch instead. */
484 tree init = do_begin_catch ();
485 tree init_type = type;
487 /* Pointers are passed by values, everything else by reference. */
488 if (!TYPE_PTR_P (type))
489 init_type = build_pointer_type (type);
490 if (init_type != TREE_TYPE (init))
491 init = build1 (NOP_EXPR, init_type, init);
492 exp = create_temporary_var (init_type);
493 DECL_REGISTER (exp) = 1;
494 cp_finish_decl (exp, init, /*init_const_expr=*/false,
495 NULL_TREE, LOOKUP_ONLYCONVERTING);
496 initialize_handler_parm (decl, exp);
503 /* Call this to end a catch block. Its responsible for emitting the
504 code to handle jumping back to the correct place, and for emitting
505 the label to jump to if this catch block didn't match. */
508 expand_end_catch_block (void)
513 /* The exception being handled is rethrown if control reaches the end of
514 a handler of the function-try-block of a constructor or destructor. */
515 if (in_function_try_handler
516 && (DECL_CONSTRUCTOR_P (current_function_decl)
517 || DECL_DESTRUCTOR_P (current_function_decl)))
518 finish_expr_stmt (build_throw (NULL_TREE));
522 begin_eh_spec_block (void)
524 tree r = build_stmt (input_location, EH_SPEC_BLOCK, NULL_TREE, NULL_TREE);
526 EH_SPEC_STMTS (r) = push_stmt_list ();
531 finish_eh_spec_block (tree raw_raises, tree eh_spec_block)
535 EH_SPEC_STMTS (eh_spec_block) = pop_stmt_list (EH_SPEC_STMTS (eh_spec_block));
537 /* Strip cv quals, etc, from the specification types. */
538 for (raises = NULL_TREE;
539 raw_raises && TREE_VALUE (raw_raises);
540 raw_raises = TREE_CHAIN (raw_raises))
542 tree type = prepare_eh_type (TREE_VALUE (raw_raises));
543 tree tinfo = eh_type_info (type);
546 raises = tree_cons (NULL_TREE, type, raises);
549 EH_SPEC_RAISES (eh_spec_block) = raises;
552 /* Return a pointer to a buffer for an exception object of type TYPE. */
555 do_allocate_exception (tree type)
559 fn = get_identifier ("__cxa_allocate_exception");
560 if (!get_global_value_if_present (fn, &fn))
562 /* Declare void *__cxa_allocate_exception(size_t) throw(). */
563 fn = declare_nothrow_library_fn (fn, ptr_type_node, size_type_node);
566 return cp_build_function_call (fn,
567 tree_cons (NULL_TREE, size_in_bytes (type),
569 tf_warning_or_error);
572 /* Call __cxa_free_exception from a cleanup. This is never invoked
573 directly, but see the comment for stabilize_throw_expr. */
576 do_free_exception (tree ptr)
580 fn = get_identifier ("__cxa_free_exception");
581 if (!get_global_value_if_present (fn, &fn))
583 /* Declare void __cxa_free_exception (void *) throw(). */
584 fn = declare_nothrow_library_fn (fn, void_type_node, ptr_type_node);
587 return cp_build_function_call (fn, tree_cons (NULL_TREE, ptr, NULL_TREE),
588 tf_warning_or_error);
591 /* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
592 Called from build_throw via walk_tree_without_duplicates. */
595 wrap_cleanups_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
596 void *data ATTRIBUTE_UNUSED)
601 /* Don't walk into types. */
607 if (TREE_CODE (exp) != TARGET_EXPR)
610 cleanup = TARGET_EXPR_CLEANUP (exp);
613 cleanup = build1 (MUST_NOT_THROW_EXPR, void_type_node, cleanup);
614 TARGET_EXPR_CLEANUP (exp) = cleanup;
617 /* Keep iterating. */
621 /* Build a throw expression. */
624 build_throw (tree exp)
628 if (exp == error_mark_node)
631 if (processing_template_decl)
634 current_function_returns_abnormally = 1;
635 return build_min (THROW_EXPR, void_type_node, exp);
638 if (exp == null_node)
639 warning (0, "throwing NULL, which has integral, not pointer type");
641 if (exp != NULL_TREE)
643 if (!is_admissible_throw_operand (exp))
644 return error_mark_node;
648 return error_mark_node;
650 if (exp && decl_is_java_type (TREE_TYPE (exp), 1))
652 tree fn = get_identifier ("_Jv_Throw");
653 if (!get_global_value_if_present (fn, &fn))
655 /* Declare void _Jv_Throw (void *). */
656 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
657 tmp = build_function_type (ptr_type_node, tmp);
658 fn = push_throw_library_fn (fn, tmp);
660 else if (really_overloaded_fn (fn))
662 error ("%qD should never be overloaded", fn);
663 return error_mark_node;
665 fn = OVL_CURRENT (fn);
666 exp = cp_build_function_call (fn, tree_cons (NULL_TREE, exp, NULL_TREE),
667 tf_warning_or_error);
676 tree temp_expr, allocate_expr;
679 /* The CLEANUP_TYPE is the internal type of a destructor. */
682 tmp = void_list_node;
683 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
684 tmp = build_function_type (void_type_node, tmp);
685 cleanup_type = build_pointer_type (tmp);
688 fn = get_identifier ("__cxa_throw");
689 if (!get_global_value_if_present (fn, &fn))
691 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
692 /* ??? Second argument is supposed to be "std::type_info*". */
693 tmp = void_list_node;
694 tmp = tree_cons (NULL_TREE, cleanup_type, tmp);
695 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
696 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
697 tmp = build_function_type (void_type_node, tmp);
698 fn = push_throw_library_fn (fn, tmp);
703 A throw-expression initializes a temporary object, the type
704 of which is determined by removing any top-level
705 cv-qualifiers from the static type of the operand of throw
706 and adjusting the type from "array of T" or "function return
707 T" to "pointer to T" or "pointer to function returning T"
709 temp_type = is_bitfield_expr_with_lowered_type (exp);
711 temp_type = type_decays_to (TREE_TYPE (exp));
713 /* OK, this is kind of wacky. The standard says that we call
714 terminate when the exception handling mechanism, after
715 completing evaluation of the expression to be thrown but
716 before the exception is caught (_except.throw_), calls a
717 user function that exits via an uncaught exception.
719 So we have to protect the actual initialization of the
720 exception object with terminate(), but evaluate the
721 expression first. Since there could be temps in the
722 expression, we need to handle that, too. We also expand
723 the call to __cxa_allocate_exception first (which doesn't
724 matter, since it can't throw). */
726 /* Allocate the space for the exception. */
727 allocate_expr = do_allocate_exception (temp_type);
728 allocate_expr = get_target_expr (allocate_expr);
729 ptr = TARGET_EXPR_SLOT (allocate_expr);
730 object = build_nop (build_pointer_type (temp_type), ptr);
731 object = cp_build_indirect_ref (object, NULL, tf_warning_or_error);
733 elided = (TREE_CODE (exp) == TARGET_EXPR);
735 /* And initialize the exception object. */
736 if (CLASS_TYPE_P (temp_type))
738 int flags = LOOKUP_NORMAL | LOOKUP_ONLYCONVERTING;
739 VEC(tree,gc) *exp_vec;
741 /* Under C++0x [12.8/16 class.copy], a thrown lvalue is sometimes
742 treated as an rvalue for the purposes of overload resolution
743 to favor move constructors over copy constructors. */
744 if (/* Must be a local, automatic variable. */
745 TREE_CODE (exp) == VAR_DECL
746 && DECL_CONTEXT (exp) == current_function_decl
747 && ! TREE_STATIC (exp)
748 /* The variable must not have the `volatile' qualifier. */
749 && !(cp_type_quals (TREE_TYPE (exp)) & TYPE_QUAL_VOLATILE))
750 flags = flags | LOOKUP_PREFER_RVALUE;
752 /* Call the copy constructor. */
753 exp_vec = make_tree_vector_single (exp);
754 exp = (build_special_member_call
755 (object, complete_ctor_identifier, &exp_vec,
756 TREE_TYPE (object), flags, tf_warning_or_error));
757 release_tree_vector (exp_vec);
758 if (exp == error_mark_node)
760 error (" in thrown expression");
761 return error_mark_node;
765 exp = build2 (INIT_EXPR, temp_type, object,
766 decay_conversion (exp));
768 /* Pre-evaluate the thrown expression first, since if we allocated
769 the space first we would have to deal with cleaning it up if
770 evaluating this expression throws.
772 The case where EXP the initializer is a cast or a function
773 returning a class is a bit of a grey area in the standard; it's
774 unclear whether or not it should be allowed to throw. We used to
775 say no, as that allowed us to optimize this case without worrying
776 about deallocating the exception object if it does. But that
777 conflicted with expectations (PR 13944) and the EDG compiler; now
778 we wrap the initialization in a TRY_CATCH_EXPR to call
779 do_free_exception rather than in a MUST_NOT_THROW_EXPR, for this
782 BUT: Issue 475 may do away with this inconsistency by removing the
783 terminate() in this situation.
785 Note that we don't check the return value from stabilize_init
786 because it will only return false in cases where elided is true,
787 and therefore we don't need to work around the failure to
789 temp_expr = NULL_TREE;
790 stabilize_init (exp, &temp_expr);
792 /* Wrap the initialization in a CLEANUP_POINT_EXPR so that cleanups
793 for temporaries within the initialization are run before the one
794 for the exception object, preserving LIFO order. */
795 exp = build1 (CLEANUP_POINT_EXPR, void_type_node, exp);
798 exp = build2 (TRY_CATCH_EXPR, void_type_node, exp,
799 do_free_exception (ptr));
801 exp = build1 (MUST_NOT_THROW_EXPR, void_type_node, exp);
803 /* Prepend the allocation. */
804 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), allocate_expr, exp);
807 /* Prepend the calculation of the throw expression. Also, force
808 any cleanups from the expression to be evaluated here so that
809 we don't have to do them during unwinding. But first wrap
810 them in MUST_NOT_THROW_EXPR, since they are run after the
811 exception object is initialized. */
812 cp_walk_tree_without_duplicates (&temp_expr, wrap_cleanups_r, 0);
813 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), temp_expr, exp);
814 exp = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (exp), exp);
817 throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object)));
819 if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (object)))
821 cleanup = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)),
822 complete_dtor_identifier, 0);
823 cleanup = BASELINK_FUNCTIONS (cleanup);
825 cxx_mark_addressable (cleanup);
826 /* Pretend it's a normal function. */
827 cleanup = build1 (ADDR_EXPR, cleanup_type, cleanup);
830 cleanup = build_int_cst (cleanup_type, 0);
832 tmp = tree_cons (NULL_TREE, cleanup, NULL_TREE);
833 tmp = tree_cons (NULL_TREE, throw_type, tmp);
834 tmp = tree_cons (NULL_TREE, ptr, tmp);
835 /* ??? Indicate that this function call throws throw_type. */
836 tmp = cp_build_function_call (fn, tmp, tf_warning_or_error);
838 /* Tack on the initialization stuff. */
839 exp = build2 (COMPOUND_EXPR, TREE_TYPE (tmp), exp, tmp);
843 /* Rethrow current exception. */
845 tree fn = get_identifier ("__cxa_rethrow");
846 if (!get_global_value_if_present (fn, &fn))
848 /* Declare void __cxa_rethrow (void). */
849 fn = push_throw_library_fn
850 (fn, build_function_type (void_type_node, void_list_node));
853 /* ??? Indicate that this function call allows exceptions of the type
854 of the enclosing catch block (if known). */
855 exp = cp_build_function_call (fn, NULL_TREE, tf_warning_or_error);
858 exp = build1 (THROW_EXPR, void_type_node, exp);
863 /* Make sure TYPE is complete, pointer to complete, reference to
864 complete, or pointer to cv void. Issue diagnostic on failure.
865 Return the zero on failure and nonzero on success. FROM can be
866 the expr or decl from whence TYPE came, if available. */
869 complete_ptr_ref_or_void_ptr_p (tree type, tree from)
873 /* Check complete. */
874 type = complete_type_or_else (type, from);
878 /* Or a pointer or ref to one, or cv void *. */
879 is_ptr = TREE_CODE (type) == POINTER_TYPE;
880 if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE)
882 tree core = TREE_TYPE (type);
884 if (is_ptr && VOID_TYPE_P (core))
886 else if (!complete_type_or_else (core, from))
892 /* Return truth-value if EXPRESSION is admissible in throw-expression,
893 i.e. if it is not of incomplete type or a pointer/reference to such
894 a type or of an abstract class type. */
897 is_admissible_throw_operand (tree expr)
899 tree type = TREE_TYPE (expr);
901 /* 15.1/4 [...] The type of the throw-expression shall not be an
902 incomplete type, or a pointer or a reference to an incomplete
903 type, other than void*, const void*, volatile void*, or
904 const volatile void*. Except for these restriction and the
905 restrictions on type matching mentioned in 15.3, the operand
906 of throw is treated exactly as a function argument in a call
907 (5.2.2) or the operand of a return statement. */
908 if (!complete_ptr_ref_or_void_ptr_p (type, expr))
911 /* 10.4/3 An abstract class shall not be used as a parameter type,
912 as a function return type or as type of an explicit
914 else if (CLASS_TYPE_P (type) && CLASSTYPE_PURE_VIRTUALS (type))
916 error ("expression %qE of abstract class type %qT cannot "
917 "be used in throw-expression", expr, type);
924 /* Returns nonzero if FN is a declaration of a standard C library
925 function which is known not to throw.
927 [lib.res.on.exception.handling]: None of the functions from the
928 Standard C library shall report an error by throwing an
929 exception, unless it calls a program-supplied function that
930 throws an exception. */
935 nothrow_libfn_p (const_tree fn)
940 && DECL_EXTERNAL (fn)
941 && DECL_NAMESPACE_SCOPE_P (fn)
942 && DECL_EXTERN_C_P (fn))
945 /* Can't be a C library function. */
948 /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME
949 unless the system headers are playing rename tricks, and if
950 they are, we don't want to be confused by them. */
952 return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id));
955 /* Returns nonzero if an exception of type FROM will be caught by a
956 handler for type TO, as per [except.handle]. */
959 can_convert_eh (tree to, tree from)
961 to = non_reference (to);
962 from = non_reference (from);
964 if (TREE_CODE (to) == POINTER_TYPE && TREE_CODE (from) == POINTER_TYPE)
967 from = TREE_TYPE (from);
969 if (! at_least_as_qualified_p (to, from))
972 if (TREE_CODE (to) == VOID_TYPE)
975 /* Else fall through. */
978 if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
979 && PUBLICLY_UNIQUELY_DERIVED_P (to, from))
985 /* Check whether any of the handlers in I are shadowed by another handler
986 accepting TYPE. Note that the shadowing may not be complete; even if
987 an exception of type B would be caught by a handler for A, there could
988 be a derived class C for which A is an ambiguous base but B is not, so
989 the handler for B would catch an exception of type C. */
992 check_handlers_1 (tree master, tree_stmt_iterator i)
994 tree type = TREE_TYPE (master);
996 for (; !tsi_end_p (i); tsi_next (&i))
998 tree handler = tsi_stmt (i);
999 if (TREE_TYPE (handler) && can_convert_eh (type, TREE_TYPE (handler)))
1001 warning (0, "%Hexception of type %qT will be caught",
1002 EXPR_LOCUS (handler), TREE_TYPE (handler));
1003 warning (0, "%H by earlier handler for %qT",
1004 EXPR_LOCUS (master), type);
1010 /* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK. */
1013 check_handlers (tree handlers)
1015 tree_stmt_iterator i;
1017 /* If we don't have a STATEMENT_LIST, then we've just got one
1018 handler, and thus nothing to warn about. */
1019 if (TREE_CODE (handlers) != STATEMENT_LIST)
1022 i = tsi_start (handlers);
1026 tree handler = tsi_stmt (i);
1029 /* No more handlers; nothing to shadow. */
1032 if (TREE_TYPE (handler) == NULL_TREE)
1033 permerror (input_location, "%H%<...%> handler must be the last handler for"
1034 " its try block", EXPR_LOCUS (handler));
1036 check_handlers_1 (handler, i);