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, 2010
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"
34 #include "tree-inline.h"
35 #include "tree-iterator.h"
39 static void push_eh_cleanup (tree);
40 static tree prepare_eh_type (tree);
41 static tree do_begin_catch (void);
42 static int dtor_nothrow (tree);
43 static tree do_end_catch (tree);
44 static bool decl_is_java_type (tree decl, int err);
45 static void initialize_handler_parm (tree, tree);
46 static tree do_allocate_exception (tree);
47 static tree wrap_cleanups_r (tree *, int *, void *);
48 static int complete_ptr_ref_or_void_ptr_p (tree, tree);
49 static bool is_admissible_throw_operand (tree);
50 static int can_convert_eh (tree, tree);
52 /* Sets up all the global eh stuff that needs to be initialized at the
53 start of compilation. */
56 init_exception_processing (void)
60 /* void std::terminate (); */
61 push_namespace (std_identifier);
62 tmp = build_function_type_list (void_type_node, NULL_TREE);
63 terminate_node = build_cp_library_fn_ptr ("terminate", tmp);
64 TREE_THIS_VOLATILE (terminate_node) = 1;
65 TREE_NOTHROW (terminate_node) = 1;
68 /* void __cxa_call_unexpected(void *); */
69 tmp = build_function_type_list (void_type_node, ptr_type_node, NULL_TREE);
71 = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp);
74 /* Returns an expression to be executed if an unhandled exception is
75 propagated out of a cleanup region. */
78 cp_protect_cleanup_actions (void)
82 When the destruction of an object during stack unwinding exits
83 using an exception ... void terminate(); is called. */
84 return terminate_node;
88 prepare_eh_type (tree type)
90 if (type == NULL_TREE)
92 if (type == error_mark_node)
93 return error_mark_node;
95 /* peel back references, so they match. */
96 type = non_reference (type);
98 /* Peel off cv qualifiers. */
99 type = TYPE_MAIN_VARIANT (type);
101 /* Functions and arrays decay to pointers. */
102 type = type_decays_to (type);
107 /* Return the type info for TYPE as used by EH machinery. */
109 eh_type_info (tree type)
113 if (type == NULL_TREE || type == error_mark_node)
116 if (decl_is_java_type (type, 0))
117 exp = build_java_class_ref (TREE_TYPE (type));
119 exp = get_tinfo_decl (type);
124 /* Build the address of a typeinfo decl for use in the runtime
125 matching field of the exception model. */
128 build_eh_type_type (tree type)
130 tree exp = eh_type_info (type);
137 return convert (ptr_type_node, build_address (exp));
143 return build_call_n (builtin_decl_explicit (BUILT_IN_EH_POINTER),
144 1, integer_zero_node);
147 /* Declare a function NAME, returning RETURN_TYPE, taking a single
148 parameter PARM_TYPE, with an empty exception specification.
150 Note that the C++ ABI document does not have a throw-specifier on
151 the routines declared below via this function. The declarations
152 are consistent with the actual implementations in libsupc++. */
155 declare_nothrow_library_fn (tree name, tree return_type, tree parm_type)
157 return push_library_fn (name, build_function_type_list (return_type,
163 /* Build up a call to __cxa_get_exception_ptr so that we can build a
164 copy constructor for the thrown object. */
167 do_get_exception_ptr (void)
171 fn = get_identifier ("__cxa_get_exception_ptr");
172 if (!get_global_value_if_present (fn, &fn))
174 /* Declare void* __cxa_get_exception_ptr (void *) throw(). */
175 fn = declare_nothrow_library_fn (fn, ptr_type_node, ptr_type_node);
178 apply_tm_attr (fn, get_identifier ("transaction_pure"));
181 return cp_build_function_call_nary (fn, tf_warning_or_error,
182 build_exc_ptr (), NULL_TREE);
185 /* Build up a call to __cxa_begin_catch, to tell the runtime that the
186 exception has been handled. */
189 do_begin_catch (void)
193 fn = get_identifier ("__cxa_begin_catch");
194 if (!get_global_value_if_present (fn, &fn))
196 /* Declare void* __cxa_begin_catch (void *) throw(). */
197 fn = declare_nothrow_library_fn (fn, ptr_type_node, ptr_type_node);
199 /* Create its transactional-memory equivalent. */
202 tree fn2 = get_identifier ("_ITM_cxa_begin_catch");
203 if (!get_global_value_if_present (fn2, &fn2))
204 fn2 = declare_nothrow_library_fn (fn2, ptr_type_node,
206 apply_tm_attr (fn2, get_identifier ("transaction_pure"));
207 record_tm_replacement (fn, fn2);
211 return cp_build_function_call_nary (fn, tf_warning_or_error,
212 build_exc_ptr (), NULL_TREE);
215 /* Returns nonzero if cleaning up an exception of type TYPE (which can be
216 NULL_TREE for a ... handler) will not throw an exception. */
219 dtor_nothrow (tree type)
221 if (type == NULL_TREE || type == error_mark_node)
224 if (TYPE_HAS_TRIVIAL_DESTRUCTOR (type))
227 if (CLASSTYPE_LAZY_DESTRUCTOR (type))
228 lazily_declare_fn (sfk_destructor, type);
230 return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type));
233 /* Build up a call to __cxa_end_catch, to destroy the exception object
234 for the current catch block if no others are currently using it. */
237 do_end_catch (tree type)
241 fn = get_identifier ("__cxa_end_catch");
242 if (!get_global_value_if_present (fn, &fn))
244 /* Declare void __cxa_end_catch (). */
245 fn = push_void_library_fn (fn, void_list_node);
246 /* This can throw if the destructor for the exception throws. */
247 TREE_NOTHROW (fn) = 0;
249 /* Create its transactional-memory equivalent. */
252 tree fn2 = get_identifier ("_ITM_cxa_end_catch");
253 if (!get_global_value_if_present (fn2, &fn2))
255 fn2 = push_void_library_fn (fn2, void_list_node);
256 TREE_NOTHROW (fn2) = 0;
258 apply_tm_attr (fn2, get_identifier ("transaction_pure"));
259 record_tm_replacement (fn, fn2);
263 cleanup = cp_build_function_call_vec (fn, NULL, tf_warning_or_error);
264 TREE_NOTHROW (cleanup) = dtor_nothrow (type);
269 /* This routine creates the cleanup for the current exception. */
272 push_eh_cleanup (tree type)
274 finish_decl_cleanup (NULL_TREE, do_end_catch (type));
277 /* Return nonzero value if DECL is a Java type suitable for catch or
281 decl_is_java_type (tree decl, int err)
283 bool r = (TREE_CODE (decl) == POINTER_TYPE
284 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
285 && TYPE_FOR_JAVA (TREE_TYPE (decl)));
289 if (TREE_CODE (decl) == REFERENCE_TYPE
290 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
291 && TYPE_FOR_JAVA (TREE_TYPE (decl)))
293 /* Can't throw a reference. */
294 error ("type %qT is disallowed in Java %<throw%> or %<catch%>",
301 = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));
303 if (jthrow_node == NULL_TREE)
305 ("call to Java %<catch%> or %<throw%> with %<jthrowable%> undefined");
307 jthrow_node = TREE_TYPE (TREE_TYPE (jthrow_node));
309 if (! DERIVED_FROM_P (jthrow_node, TREE_TYPE (decl)))
311 /* Thrown object must be a Throwable. */
312 error ("type %qT is not derived from %<java::lang::Throwable%>",
321 /* Select the personality routine to be used for exception handling,
322 or issue an error if we need two different ones in the same
324 ??? At present DECL_FUNCTION_PERSONALITY is set via
325 LANG_HOOKS_EH_PERSONALITY. Should it be done here instead? */
327 choose_personality_routine (enum languages lang)
342 if (lang != lang_cplusplus)
347 if (lang != lang_java)
352 ; /* Proceed to language selection. */
363 terminate_node = builtin_decl_explicit (BUILT_IN_ABORT);
364 pragma_java_exceptions = true;
373 error ("mixing C++ and Java catches in a single translation unit");
377 /* Wrap EXPR in a MUST_NOT_THROW_EXPR expressing that EXPR must
378 not throw any exceptions if COND is true. A condition of
379 NULL_TREE is treated as 'true'. */
382 build_must_not_throw_expr (tree body, tree cond)
384 tree type = body ? TREE_TYPE (body) : void_type_node;
386 if (cond && !value_dependent_expression_p (cond))
388 cond = cxx_constant_value (cond);
389 if (integer_zerop (cond))
391 else if (integer_onep (cond))
395 return build2 (MUST_NOT_THROW_EXPR, type, body, cond);
399 /* Initialize the catch parameter DECL. */
402 initialize_handler_parm (tree decl, tree exp)
407 /* Make sure we mark the catch param as used, otherwise we'll get a
408 warning about an unused ((anonymous)). */
409 TREE_USED (decl) = 1;
410 DECL_READ_P (decl) = 1;
412 /* Figure out the type that the initializer is. Pointers are returned
413 adjusted by value from __cxa_begin_catch. Others are returned by
415 init_type = TREE_TYPE (decl);
416 if (!POINTER_TYPE_P (init_type))
417 init_type = build_reference_type (init_type);
419 choose_personality_routine (decl_is_java_type (init_type, 0)
420 ? lang_java : lang_cplusplus);
422 /* Since pointers are passed by value, initialize a reference to
423 pointer catch parm with the address of the temporary. */
424 if (TREE_CODE (init_type) == REFERENCE_TYPE
425 && TYPE_PTR_P (TREE_TYPE (init_type)))
426 exp = cp_build_addr_expr (exp, tf_warning_or_error);
428 exp = ocp_convert (init_type, exp, CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
430 init = convert_from_reference (exp);
432 /* If the constructor for the catch parm exits via an exception, we
433 must call terminate. See eh23.C. */
434 if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
436 /* Generate the copy constructor call directly so we can wrap it.
437 See also expand_default_init. */
438 init = ocp_convert (TREE_TYPE (decl), init,
439 CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
440 /* Force cleanups now to avoid nesting problems with the
441 MUST_NOT_THROW_EXPR. */
442 init = fold_build_cleanup_point_expr (TREE_TYPE (init), init);
443 init = build_must_not_throw_expr (init, NULL_TREE);
446 decl = pushdecl (decl);
448 start_decl_1 (decl, true);
449 cp_finish_decl (decl, init, /*init_const_expr_p=*/false, NULL_TREE,
450 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
454 /* Routine to see if exception handling is turned on.
455 DO_WARN is nonzero if we want to inform the user that exception
456 handling is turned off.
458 This is used to ensure that -fexceptions has been specified if the
459 compiler tries to use any exception-specific functions. */
464 if (! flag_exceptions)
466 static int warned = 0;
469 error ("exception handling disabled, use -fexceptions to enable");
477 /* Call this to start a catch block. DECL is the catch parameter. */
480 expand_start_catch_block (tree decl)
488 /* Make sure this declaration is reasonable. */
489 if (decl && !complete_ptr_ref_or_void_ptr_p (TREE_TYPE (decl), NULL_TREE))
490 decl = error_mark_node;
493 type = prepare_eh_type (TREE_TYPE (decl));
497 if (decl && decl_is_java_type (type, 1))
499 /* Java only passes object via pointer and doesn't require
500 adjusting. The java object is immediately before the
501 generic exception header. */
502 exp = build_exc_ptr ();
503 exp = build1 (NOP_EXPR, build_pointer_type (type), exp);
504 exp = fold_build_pointer_plus (exp,
505 fold_build1_loc (input_location,
506 NEGATE_EXPR, sizetype,
507 TYPE_SIZE_UNIT (TREE_TYPE (exp))));
508 exp = cp_build_indirect_ref (exp, RO_NULL, tf_warning_or_error);
509 initialize_handler_parm (decl, exp);
513 /* Call __cxa_end_catch at the end of processing the exception. */
514 push_eh_cleanup (type);
516 init = do_begin_catch ();
518 /* If there's no decl at all, then all we need to do is make sure
519 to tell the runtime that we've begun handling the exception. */
520 if (decl == NULL || decl == error_mark_node || init == error_mark_node)
521 finish_expr_stmt (init);
523 /* If the C++ object needs constructing, we need to do that before
524 calling __cxa_begin_catch, so that std::uncaught_exception gets
525 the right value during the copy constructor. */
526 else if (flag_use_cxa_get_exception_ptr
527 && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
529 exp = do_get_exception_ptr ();
530 initialize_handler_parm (decl, exp);
531 finish_expr_stmt (init);
534 /* Otherwise the type uses a bitwise copy, and we don't have to worry
535 about the value of std::uncaught_exception and therefore can do the
536 copy with the return value of __cxa_end_catch instead. */
539 tree init_type = type;
541 /* Pointers are passed by values, everything else by reference. */
542 if (!TYPE_PTR_P (type))
543 init_type = build_pointer_type (type);
544 if (init_type != TREE_TYPE (init))
545 init = build1 (NOP_EXPR, init_type, init);
546 exp = create_temporary_var (init_type);
547 DECL_REGISTER (exp) = 1;
548 cp_finish_decl (exp, init, /*init_const_expr=*/false,
549 NULL_TREE, LOOKUP_ONLYCONVERTING);
550 initialize_handler_parm (decl, exp);
557 /* Call this to end a catch block. Its responsible for emitting the
558 code to handle jumping back to the correct place, and for emitting
559 the label to jump to if this catch block didn't match. */
562 expand_end_catch_block (void)
567 /* The exception being handled is rethrown if control reaches the end of
568 a handler of the function-try-block of a constructor or destructor. */
569 if (in_function_try_handler
570 && (DECL_CONSTRUCTOR_P (current_function_decl)
571 || DECL_DESTRUCTOR_P (current_function_decl)))
572 finish_expr_stmt (build_throw (NULL_TREE));
576 begin_eh_spec_block (void)
579 location_t spec_location = DECL_SOURCE_LOCATION (current_function_decl);
581 /* A noexcept specification (or throw() with -fnothrow-opt) is a
582 MUST_NOT_THROW_EXPR. */
583 if (TYPE_NOEXCEPT_P (TREE_TYPE (current_function_decl)))
585 r = build_stmt (spec_location, MUST_NOT_THROW_EXPR,
586 NULL_TREE, NULL_TREE);
587 TREE_SIDE_EFFECTS (r) = 1;
590 r = build_stmt (spec_location, EH_SPEC_BLOCK, NULL_TREE, NULL_TREE);
592 TREE_OPERAND (r, 0) = push_stmt_list ();
597 finish_eh_spec_block (tree raw_raises, tree eh_spec_block)
601 TREE_OPERAND (eh_spec_block, 0)
602 = pop_stmt_list (TREE_OPERAND (eh_spec_block, 0));
604 if (TREE_CODE (eh_spec_block) == MUST_NOT_THROW_EXPR)
607 /* Strip cv quals, etc, from the specification types. */
608 for (raises = NULL_TREE;
609 raw_raises && TREE_VALUE (raw_raises);
610 raw_raises = TREE_CHAIN (raw_raises))
612 tree type = prepare_eh_type (TREE_VALUE (raw_raises));
613 tree tinfo = eh_type_info (type);
616 raises = tree_cons (NULL_TREE, type, raises);
619 EH_SPEC_RAISES (eh_spec_block) = raises;
622 /* Return a pointer to a buffer for an exception object of type TYPE. */
625 do_allocate_exception (tree type)
629 fn = get_identifier ("__cxa_allocate_exception");
630 if (!get_global_value_if_present (fn, &fn))
632 /* Declare void *__cxa_allocate_exception(size_t) throw(). */
633 fn = declare_nothrow_library_fn (fn, ptr_type_node, size_type_node);
637 tree fn2 = get_identifier ("_ITM_cxa_allocate_exception");
638 if (!get_global_value_if_present (fn2, &fn2))
639 fn2 = declare_nothrow_library_fn (fn2, ptr_type_node,
641 apply_tm_attr (fn2, get_identifier ("transaction_pure"));
642 record_tm_replacement (fn, fn2);
646 return cp_build_function_call_nary (fn, tf_warning_or_error,
647 size_in_bytes (type), NULL_TREE);
650 /* Call __cxa_free_exception from a cleanup. This is never invoked
651 directly, but see the comment for stabilize_throw_expr. */
654 do_free_exception (tree ptr)
658 fn = get_identifier ("__cxa_free_exception");
659 if (!get_global_value_if_present (fn, &fn))
661 /* Declare void __cxa_free_exception (void *) throw(). */
662 fn = declare_nothrow_library_fn (fn, void_type_node, ptr_type_node);
665 return cp_build_function_call_nary (fn, tf_warning_or_error, ptr, NULL_TREE);
668 /* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
669 Called from build_throw via walk_tree_without_duplicates. */
672 wrap_cleanups_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
673 void *data ATTRIBUTE_UNUSED)
678 /* Don't walk into types. */
684 if (TREE_CODE (exp) != TARGET_EXPR)
687 cleanup = TARGET_EXPR_CLEANUP (exp);
690 cleanup = build2 (MUST_NOT_THROW_EXPR, void_type_node, cleanup,
692 TARGET_EXPR_CLEANUP (exp) = cleanup;
695 /* Keep iterating. */
699 /* Build a throw expression. */
702 build_throw (tree exp)
706 if (exp == error_mark_node)
709 if (processing_template_decl)
712 current_function_returns_abnormally = 1;
713 exp = build_min (THROW_EXPR, void_type_node, exp);
714 SET_EXPR_LOCATION (exp, input_location);
718 if (exp == null_node)
719 warning (0, "throwing NULL, which has integral, not pointer type");
721 if (exp != NULL_TREE)
723 if (!is_admissible_throw_operand (exp))
724 return error_mark_node;
728 return error_mark_node;
730 if (exp && decl_is_java_type (TREE_TYPE (exp), 1))
732 tree fn = get_identifier ("_Jv_Throw");
733 if (!get_global_value_if_present (fn, &fn))
735 /* Declare void _Jv_Throw (void *). */
737 tmp = build_function_type_list (ptr_type_node,
738 ptr_type_node, NULL_TREE);
739 fn = push_throw_library_fn (fn, tmp);
741 else if (really_overloaded_fn (fn))
743 error ("%qD should never be overloaded", fn);
744 return error_mark_node;
746 fn = OVL_CURRENT (fn);
747 exp = cp_build_function_call_nary (fn, tf_warning_or_error,
759 /* The CLEANUP_TYPE is the internal type of a destructor. */
762 tmp = build_function_type_list (void_type_node,
763 ptr_type_node, NULL_TREE);
764 cleanup_type = build_pointer_type (tmp);
767 fn = get_identifier ("__cxa_throw");
768 if (!get_global_value_if_present (fn, &fn))
770 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
771 /* ??? Second argument is supposed to be "std::type_info*". */
772 tmp = build_function_type_list (void_type_node,
773 ptr_type_node, ptr_type_node,
774 cleanup_type, NULL_TREE);
775 fn = push_throw_library_fn (fn, tmp);
779 tree fn2 = get_identifier ("_ITM_cxa_throw");
780 if (!get_global_value_if_present (fn2, &fn2))
781 fn2 = push_throw_library_fn (fn2, tmp);
782 apply_tm_attr (fn2, get_identifier ("transaction_pure"));
783 record_tm_replacement (fn, fn2);
789 A throw-expression initializes a temporary object, the type
790 of which is determined by removing any top-level
791 cv-qualifiers from the static type of the operand of throw
792 and adjusting the type from "array of T" or "function return
793 T" to "pointer to T" or "pointer to function returning T"
795 temp_type = is_bitfield_expr_with_lowered_type (exp);
797 temp_type = cv_unqualified (type_decays_to (TREE_TYPE (exp)));
799 /* OK, this is kind of wacky. The standard says that we call
800 terminate when the exception handling mechanism, after
801 completing evaluation of the expression to be thrown but
802 before the exception is caught (_except.throw_), calls a
803 user function that exits via an uncaught exception.
805 So we have to protect the actual initialization of the
806 exception object with terminate(), but evaluate the
807 expression first. Since there could be temps in the
808 expression, we need to handle that, too. We also expand
809 the call to __cxa_allocate_exception first (which doesn't
810 matter, since it can't throw). */
812 /* Allocate the space for the exception. */
813 allocate_expr = do_allocate_exception (temp_type);
814 allocate_expr = get_target_expr (allocate_expr);
815 ptr = TARGET_EXPR_SLOT (allocate_expr);
816 TARGET_EXPR_CLEANUP (allocate_expr) = do_free_exception (ptr);
817 CLEANUP_EH_ONLY (allocate_expr) = 1;
819 object = build_nop (build_pointer_type (temp_type), ptr);
820 object = cp_build_indirect_ref (object, RO_NULL, tf_warning_or_error);
822 /* And initialize the exception object. */
823 if (CLASS_TYPE_P (temp_type))
825 int flags = LOOKUP_NORMAL | LOOKUP_ONLYCONVERTING;
826 VEC(tree,gc) *exp_vec;
828 /* Under C++0x [12.8/16 class.copy], a thrown lvalue is sometimes
829 treated as an rvalue for the purposes of overload resolution
830 to favor move constructors over copy constructors. */
831 if (/* Must be a local, automatic variable. */
832 TREE_CODE (exp) == VAR_DECL
833 && DECL_CONTEXT (exp) == current_function_decl
834 && ! TREE_STATIC (exp)
835 /* The variable must not have the `volatile' qualifier. */
836 && !(cp_type_quals (TREE_TYPE (exp)) & TYPE_QUAL_VOLATILE))
837 flags = flags | LOOKUP_PREFER_RVALUE;
839 /* Call the copy constructor. */
840 exp_vec = make_tree_vector_single (exp);
841 exp = (build_special_member_call
842 (object, complete_ctor_identifier, &exp_vec,
843 TREE_TYPE (object), flags, tf_warning_or_error));
844 release_tree_vector (exp_vec);
845 if (exp == error_mark_node)
847 error (" in thrown expression");
848 return error_mark_node;
853 tmp = decay_conversion (exp);
854 if (tmp == error_mark_node)
855 return error_mark_node;
856 exp = build2 (INIT_EXPR, temp_type, object, tmp);
859 /* Mark any cleanups from the initialization as MUST_NOT_THROW, since
860 they are run after the exception object is initialized. */
861 cp_walk_tree_without_duplicates (&exp, wrap_cleanups_r, 0);
863 /* Prepend the allocation. */
864 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), allocate_expr, exp);
866 /* Force all the cleanups to be evaluated here so that we don't have
867 to do them during unwinding. */
868 exp = build1 (CLEANUP_POINT_EXPR, void_type_node, exp);
870 throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object)));
872 if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (object)))
874 cleanup = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)),
875 complete_dtor_identifier, 0);
876 cleanup = BASELINK_FUNCTIONS (cleanup);
878 cxx_mark_addressable (cleanup);
879 /* Pretend it's a normal function. */
880 cleanup = build1 (ADDR_EXPR, cleanup_type, cleanup);
883 cleanup = build_int_cst (cleanup_type, 0);
885 /* ??? Indicate that this function call throws throw_type. */
886 tmp = cp_build_function_call_nary (fn, tf_warning_or_error,
887 ptr, throw_type, cleanup, NULL_TREE);
889 /* Tack on the initialization stuff. */
890 exp = build2 (COMPOUND_EXPR, TREE_TYPE (tmp), exp, tmp);
894 /* Rethrow current exception. */
896 tree fn = get_identifier ("__cxa_rethrow");
897 if (!get_global_value_if_present (fn, &fn))
899 /* Declare void __cxa_rethrow (void). */
900 fn = push_throw_library_fn
901 (fn, build_function_type_list (void_type_node, NULL_TREE));
905 apply_tm_attr (fn, get_identifier ("transaction_pure"));
907 /* ??? Indicate that this function call allows exceptions of the type
908 of the enclosing catch block (if known). */
909 exp = cp_build_function_call_vec (fn, NULL, tf_warning_or_error);
912 exp = build1 (THROW_EXPR, void_type_node, exp);
913 SET_EXPR_LOCATION (exp, input_location);
918 /* Make sure TYPE is complete, pointer to complete, reference to
919 complete, or pointer to cv void. Issue diagnostic on failure.
920 Return the zero on failure and nonzero on success. FROM can be
921 the expr or decl from whence TYPE came, if available. */
924 complete_ptr_ref_or_void_ptr_p (tree type, tree from)
928 /* Check complete. */
929 type = complete_type_or_else (type, from);
933 /* Or a pointer or ref to one, or cv void *. */
934 is_ptr = TREE_CODE (type) == POINTER_TYPE;
935 if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE)
937 tree core = TREE_TYPE (type);
939 if (is_ptr && VOID_TYPE_P (core))
941 else if (!complete_type_or_else (core, from))
947 /* Return truth-value if EXPRESSION is admissible in throw-expression,
948 i.e. if it is not of incomplete type or a pointer/reference to such
949 a type or of an abstract class type. */
952 is_admissible_throw_operand (tree expr)
954 tree type = TREE_TYPE (expr);
956 /* 15.1/4 [...] The type of the throw-expression shall not be an
957 incomplete type, or a pointer or a reference to an incomplete
958 type, other than void*, const void*, volatile void*, or
959 const volatile void*. Except for these restriction and the
960 restrictions on type matching mentioned in 15.3, the operand
961 of throw is treated exactly as a function argument in a call
962 (5.2.2) or the operand of a return statement. */
963 if (!complete_ptr_ref_or_void_ptr_p (type, expr))
966 /* 10.4/3 An abstract class shall not be used as a parameter type,
967 as a function return type or as type of an explicit
969 else if (CLASS_TYPE_P (type) && CLASSTYPE_PURE_VIRTUALS (type))
971 error ("expression %qE of abstract class type %qT cannot "
972 "be used in throw-expression", expr, type);
979 /* Returns nonzero if FN is a declaration of a standard C library
980 function which is known not to throw.
982 [lib.res.on.exception.handling]: None of the functions from the
983 Standard C library shall report an error by throwing an
984 exception, unless it calls a program-supplied function that
985 throws an exception. */
990 nothrow_libfn_p (const_tree fn)
995 && DECL_EXTERNAL (fn)
996 && DECL_NAMESPACE_SCOPE_P (fn)
997 && DECL_EXTERN_C_P (fn))
1000 /* Can't be a C library function. */
1003 /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME
1004 unless the system headers are playing rename tricks, and if
1005 they are, we don't want to be confused by them. */
1006 id = DECL_NAME (fn);
1007 return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id));
1010 /* Returns nonzero if an exception of type FROM will be caught by a
1011 handler for type TO, as per [except.handle]. */
1014 can_convert_eh (tree to, tree from)
1016 to = non_reference (to);
1017 from = non_reference (from);
1019 if (TREE_CODE (to) == POINTER_TYPE && TREE_CODE (from) == POINTER_TYPE)
1021 to = TREE_TYPE (to);
1022 from = TREE_TYPE (from);
1024 if (! at_least_as_qualified_p (to, from))
1027 if (TREE_CODE (to) == VOID_TYPE)
1030 /* Else fall through. */
1033 if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
1034 && PUBLICLY_UNIQUELY_DERIVED_P (to, from))
1040 /* Check whether any of the handlers in I are shadowed by another handler
1041 accepting TYPE. Note that the shadowing may not be complete; even if
1042 an exception of type B would be caught by a handler for A, there could
1043 be a derived class C for which A is an ambiguous base but B is not, so
1044 the handler for B would catch an exception of type C. */
1047 check_handlers_1 (tree master, tree_stmt_iterator i)
1049 tree type = TREE_TYPE (master);
1051 for (; !tsi_end_p (i); tsi_next (&i))
1053 tree handler = tsi_stmt (i);
1054 if (TREE_TYPE (handler) && can_convert_eh (type, TREE_TYPE (handler)))
1056 warning_at (EXPR_LOCATION (handler), 0,
1057 "exception of type %qT will be caught",
1058 TREE_TYPE (handler));
1059 warning_at (EXPR_LOCATION (master), 0,
1060 " by earlier handler for %qT", type);
1066 /* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK. */
1069 check_handlers (tree handlers)
1071 tree_stmt_iterator i;
1073 /* If we don't have a STATEMENT_LIST, then we've just got one
1074 handler, and thus nothing to warn about. */
1075 if (TREE_CODE (handlers) != STATEMENT_LIST)
1078 i = tsi_start (handlers);
1082 tree handler = tsi_stmt (i);
1085 /* No more handlers; nothing to shadow. */
1088 if (TREE_TYPE (handler) == NULL_TREE)
1089 permerror (EXPR_LOCATION (handler), "%<...%>"
1090 " handler must be the last handler for its try block");
1092 check_handlers_1 (handler, i);
1096 /* walk_tree helper for finish_noexcept_expr. Returns non-null if the
1097 expression *TP causes the noexcept operator to evaluate to false.
1099 5.3.7 [expr.noexcept]: The result of the noexcept operator is false if
1100 in a potentially-evaluated context the expression would contain
1101 * a potentially evaluated call to a function, member function,
1102 function pointer, or member function pointer that does not have a
1103 non-throwing exception-specification (15.4),
1104 * a potentially evaluated throw-expression (15.1),
1105 * a potentially evaluated dynamic_cast expression dynamic_cast<T>(v),
1106 where T is a reference type, that requires a run-time check (5.2.7), or
1107 * a potentially evaluated typeid expression (5.2.8) applied to a glvalue
1108 expression whose type is a polymorphic class type (10.3). */
1111 check_noexcept_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
1112 void *data ATTRIBUTE_UNUSED)
1115 enum tree_code code = TREE_CODE (t);
1116 if (code == CALL_EXPR
1117 || code == AGGR_INIT_EXPR)
1119 /* We can only use the exception specification of the called function
1120 for determining the value of a noexcept expression; we can't use
1121 TREE_NOTHROW, as it might have a different value in another
1122 translation unit, creating ODR problems.
1124 We could use TREE_NOTHROW (t) for !TREE_PUBLIC fns, though... */
1125 tree fn = (code == AGGR_INIT_EXPR
1126 ? AGGR_INIT_EXPR_FN (t) : CALL_EXPR_FN (t));
1127 tree type = TREE_TYPE (TREE_TYPE (fn));
1130 if (TREE_CODE (fn) == ADDR_EXPR)
1131 fn = TREE_OPERAND (fn, 0);
1132 if (TREE_CODE (fn) == FUNCTION_DECL)
1134 /* We do use TREE_NOTHROW for ABI internals like __dynamic_cast,
1135 and for C library functions known not to throw. */
1136 if (DECL_EXTERN_C_P (fn)
1137 && (DECL_ARTIFICIAL (fn)
1138 || nothrow_libfn_p (fn)))
1139 return TREE_NOTHROW (fn) ? NULL_TREE : fn;
1140 /* A call to a constexpr function is noexcept if the call
1141 is a constant expression. */
1142 if (DECL_DECLARED_CONSTEXPR_P (fn)
1143 && is_sub_constant_expr (t))
1146 if (!TYPE_NOTHROW_P (type))
1153 /* If a function that causes a noexcept-expression to be false isn't
1154 defined yet, remember it and check it for TREE_NOTHROW again at EOF. */
1156 typedef struct GTY(()) pending_noexcept {
1160 DEF_VEC_O(pending_noexcept);
1161 DEF_VEC_ALLOC_O(pending_noexcept,gc);
1162 static GTY(()) VEC(pending_noexcept,gc) *pending_noexcept_checks;
1164 /* FN is a FUNCTION_DECL that caused a noexcept-expr to be false. Warn if
1168 maybe_noexcept_warning (tree fn)
1170 if (TREE_NOTHROW (fn))
1172 warning (OPT_Wnoexcept, "noexcept-expression evaluates to %<false%> "
1173 "because of a call to %qD", fn);
1174 warning (OPT_Wnoexcept, "but %q+D does not throw; perhaps "
1175 "it should be declared %<noexcept%>", fn);
1179 /* Check any functions that weren't defined earlier when they caused a
1180 noexcept expression to evaluate to false. */
1183 perform_deferred_noexcept_checks (void)
1186 pending_noexcept *p;
1187 location_t saved_loc = input_location;
1188 FOR_EACH_VEC_ELT (pending_noexcept, pending_noexcept_checks, i, p)
1190 input_location = p->loc;
1191 maybe_noexcept_warning (p->fn);
1193 input_location = saved_loc;
1196 /* Evaluate noexcept ( EXPR ). */
1199 finish_noexcept_expr (tree expr, tsubst_flags_t complain)
1201 if (expr == error_mark_node)
1202 return error_mark_node;
1204 if (processing_template_decl)
1205 return build_min (NOEXCEPT_EXPR, boolean_type_node, expr);
1207 return (expr_noexcept_p (expr, complain)
1208 ? boolean_true_node : boolean_false_node);
1211 /* Returns whether EXPR is noexcept, possibly warning if allowed by
1215 expr_noexcept_p (tree expr, tsubst_flags_t complain)
1219 if (expr == error_mark_node)
1222 fn = cp_walk_tree_without_duplicates (&expr, check_noexcept_r, 0);
1225 if ((complain & tf_warning) && warn_noexcept
1226 && TREE_CODE (fn) == FUNCTION_DECL)
1228 if (!DECL_INITIAL (fn))
1230 /* Not defined yet; check again at EOF. */
1232 = VEC_safe_push (pending_noexcept, gc,
1233 pending_noexcept_checks, NULL);
1235 p->loc = input_location;
1238 maybe_noexcept_warning (fn);
1246 /* Return true iff SPEC is throw() or noexcept(true). */
1249 nothrow_spec_p (const_tree spec)
1251 gcc_assert (!DEFERRED_NOEXCEPT_SPEC_P (spec));
1252 if (spec == NULL_TREE
1253 || TREE_VALUE (spec) != NULL_TREE
1254 || spec == noexcept_false_spec)
1256 if (TREE_PURPOSE (spec) == NULL_TREE
1257 || spec == noexcept_true_spec)
1259 gcc_assert (processing_template_decl
1260 || TREE_PURPOSE (spec) == error_mark_node);
1264 /* For FUNCTION_TYPE or METHOD_TYPE, true if NODE is noexcept. This is the
1265 case for things declared noexcept(true) and, with -fnothrow-opt, for
1266 throw() functions. */
1269 type_noexcept_p (const_tree type)
1271 tree spec = TYPE_RAISES_EXCEPTIONS (type);
1272 gcc_assert (!DEFERRED_NOEXCEPT_SPEC_P (spec));
1273 if (flag_nothrow_opt)
1274 return nothrow_spec_p (spec);
1276 return spec == noexcept_true_spec;
1279 /* For FUNCTION_TYPE or METHOD_TYPE, true if NODE can throw any type,
1280 i.e. no exception-specification or noexcept(false). */
1283 type_throw_all_p (const_tree type)
1285 tree spec = TYPE_RAISES_EXCEPTIONS (type);
1286 gcc_assert (!DEFERRED_NOEXCEPT_SPEC_P (spec));
1287 return spec == NULL_TREE || spec == noexcept_false_spec;
1290 /* Create a representation of the noexcept-specification with
1291 constant-expression of EXPR. COMPLAIN is as for tsubst. */
1294 build_noexcept_spec (tree expr, int complain)
1296 /* This isn't part of the signature, so don't bother trying to evaluate
1297 it until instantiation. */
1298 if (!processing_template_decl && TREE_CODE (expr) != DEFERRED_NOEXCEPT)
1300 expr = perform_implicit_conversion_flags (boolean_type_node, expr,
1303 expr = cxx_constant_value (expr);
1305 if (TREE_CODE (expr) == INTEGER_CST)
1307 if (operand_equal_p (expr, boolean_true_node, 0))
1308 return noexcept_true_spec;
1311 gcc_checking_assert (operand_equal_p (expr, boolean_false_node, 0));
1312 return noexcept_false_spec;
1315 else if (expr == error_mark_node)
1316 return error_mark_node;
1319 gcc_assert (processing_template_decl
1320 || TREE_CODE (expr) == DEFERRED_NOEXCEPT);
1321 return build_tree_list (expr, NULL_TREE);
1325 #include "gt-cp-except.h"