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"
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 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 lang_protect_cleanup_actions = &cp_protect_cleanup_actions;
83 /* Returns an expression to be executed if an unhandled exception is
84 propagated out of a cleanup region. */
87 cp_protect_cleanup_actions (void)
91 When the destruction of an object during stack unwinding exits
92 using an exception ... void terminate(); is called. */
93 return terminate_node;
97 prepare_eh_type (tree type)
99 if (type == NULL_TREE)
101 if (type == error_mark_node)
102 return error_mark_node;
104 /* peel back references, so they match. */
105 type = non_reference (type);
107 /* Peel off cv qualifiers. */
108 type = TYPE_MAIN_VARIANT (type);
110 /* Functions and arrays decay to pointers. */
111 type = type_decays_to (type);
116 /* Return the type info for TYPE as used by EH machinery. */
118 eh_type_info (tree type)
122 if (type == NULL_TREE || type == error_mark_node)
125 if (decl_is_java_type (type, 0))
126 exp = build_java_class_ref (TREE_TYPE (type));
128 exp = get_tinfo_decl (type);
133 /* Build the address of a typeinfo decl for use in the runtime
134 matching field of the exception model. */
137 build_eh_type_type (tree type)
139 tree exp = eh_type_info (type);
146 return convert (ptr_type_node, build_address (exp));
152 return build_call_n (built_in_decls [BUILT_IN_EH_POINTER],
153 1, integer_zero_node);
156 /* Declare a function NAME, returning RETURN_TYPE, taking a single
157 parameter PARM_TYPE, with an empty exception specification.
159 Note that the C++ ABI document does not have a throw-specifier on
160 the routines declared below via this function. The declarations
161 are consistent with the actual implementations in libsupc++. */
164 declare_nothrow_library_fn (tree name, tree return_type, tree parm_type)
166 tree tmp = tree_cons (NULL_TREE, parm_type, void_list_node);
167 return push_library_fn (name, build_function_type (return_type, tmp),
171 /* Build up a call to __cxa_get_exception_ptr so that we can build a
172 copy constructor for the thrown object. */
175 do_get_exception_ptr (void)
179 fn = get_identifier ("__cxa_get_exception_ptr");
180 if (!get_global_value_if_present (fn, &fn))
182 /* Declare void* __cxa_get_exception_ptr (void *) throw(). */
183 fn = declare_nothrow_library_fn (fn, ptr_type_node, ptr_type_node);
186 return cp_build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
188 tf_warning_or_error);
191 /* Build up a call to __cxa_begin_catch, to tell the runtime that the
192 exception has been handled. */
195 do_begin_catch (void)
199 fn = get_identifier ("__cxa_begin_catch");
200 if (!get_global_value_if_present (fn, &fn))
202 /* Declare void* __cxa_begin_catch (void *) throw(). */
203 fn = declare_nothrow_library_fn (fn, ptr_type_node, ptr_type_node);
206 return cp_build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
208 tf_warning_or_error);
211 /* Returns nonzero if cleaning up an exception of type TYPE (which can be
212 NULL_TREE for a ... handler) will not throw an exception. */
215 dtor_nothrow (tree type)
217 if (type == NULL_TREE)
220 if (!CLASS_TYPE_P (type))
223 if (CLASSTYPE_LAZY_DESTRUCTOR (type))
224 lazily_declare_fn (sfk_destructor, type);
226 return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type));
229 /* Build up a call to __cxa_end_catch, to destroy the exception object
230 for the current catch block if no others are currently using it. */
233 do_end_catch (tree type)
237 fn = get_identifier ("__cxa_end_catch");
238 if (!get_global_value_if_present (fn, &fn))
240 /* Declare void __cxa_end_catch (). */
241 fn = push_void_library_fn (fn, void_list_node);
242 /* This can throw if the destructor for the exception throws. */
243 TREE_NOTHROW (fn) = 0;
246 cleanup = cp_build_function_call (fn, NULL_TREE, tf_warning_or_error);
247 TREE_NOTHROW (cleanup) = dtor_nothrow (type);
252 /* This routine creates the cleanup for the current exception. */
255 push_eh_cleanup (tree type)
257 finish_decl_cleanup (NULL_TREE, do_end_catch (type));
260 /* Return nonzero value if DECL is a Java type suitable for catch or
264 decl_is_java_type (tree decl, int err)
266 bool r = (TREE_CODE (decl) == POINTER_TYPE
267 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
268 && TYPE_FOR_JAVA (TREE_TYPE (decl)));
272 if (TREE_CODE (decl) == REFERENCE_TYPE
273 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
274 && TYPE_FOR_JAVA (TREE_TYPE (decl)))
276 /* Can't throw a reference. */
277 error ("type %qT is disallowed in Java %<throw%> or %<catch%>",
284 = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));
286 if (jthrow_node == NULL_TREE)
288 ("call to Java %<catch%> or %<throw%> with %<jthrowable%> undefined");
290 jthrow_node = TREE_TYPE (TREE_TYPE (jthrow_node));
292 if (! DERIVED_FROM_P (jthrow_node, TREE_TYPE (decl)))
294 /* Thrown object must be a Throwable. */
295 error ("type %qT is not derived from %<java::lang::Throwable%>",
304 /* Select the personality routine to be used for exception handling,
305 or issue an error if we need two different ones in the same
307 ??? At present eh_personality_decl is set to
308 __gxx_personality_(sj|v)0 in init_exception_processing - should it
309 be done here instead? */
311 choose_personality_routine (enum languages lang)
326 if (lang != lang_cplusplus)
331 if (lang != lang_java)
336 ; /* Proceed to language selection. */
347 terminate_node = built_in_decls [BUILT_IN_ABORT];
348 pragma_java_exceptions = true;
357 error ("mixing C++ and Java catches in a single translation unit");
361 /* Initialize the catch parameter DECL. */
364 initialize_handler_parm (tree decl, tree exp)
369 /* Make sure we mark the catch param as used, otherwise we'll get a
370 warning about an unused ((anonymous)). */
371 TREE_USED (decl) = 1;
373 /* Figure out the type that the initializer is. Pointers are returned
374 adjusted by value from __cxa_begin_catch. Others are returned by
376 init_type = TREE_TYPE (decl);
377 if (!POINTER_TYPE_P (init_type))
378 init_type = build_reference_type (init_type);
380 choose_personality_routine (decl_is_java_type (init_type, 0)
381 ? lang_java : lang_cplusplus);
383 /* Since pointers are passed by value, initialize a reference to
384 pointer catch parm with the address of the temporary. */
385 if (TREE_CODE (init_type) == REFERENCE_TYPE
386 && TYPE_PTR_P (TREE_TYPE (init_type)))
387 exp = cp_build_unary_op (ADDR_EXPR, exp, 1, tf_warning_or_error);
389 exp = ocp_convert (init_type, exp, CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
391 init = convert_from_reference (exp);
393 /* If the constructor for the catch parm exits via an exception, we
394 must call terminate. See eh23.C. */
395 if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
397 /* Generate the copy constructor call directly so we can wrap it.
398 See also expand_default_init. */
399 init = ocp_convert (TREE_TYPE (decl), init,
400 CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
401 /* Force cleanups now to avoid nesting problems with the
402 MUST_NOT_THROW_EXPR. */
403 init = fold_build_cleanup_point_expr (TREE_TYPE (init), init);
404 init = build1 (MUST_NOT_THROW_EXPR, TREE_TYPE (init), init);
407 decl = pushdecl (decl);
409 start_decl_1 (decl, true);
410 cp_finish_decl (decl, init, /*init_const_expr_p=*/false, NULL_TREE,
411 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
414 /* Call this to start a catch block. DECL is the catch parameter. */
417 expand_start_catch_block (tree decl)
425 /* Make sure this declaration is reasonable. */
426 if (decl && !complete_ptr_ref_or_void_ptr_p (TREE_TYPE (decl), NULL_TREE))
427 decl = error_mark_node;
430 type = prepare_eh_type (TREE_TYPE (decl));
434 if (decl && decl_is_java_type (type, 1))
436 /* Java only passes object via pointer and doesn't require
437 adjusting. The java object is immediately before the
438 generic exception header. */
439 exp = build_exc_ptr ();
440 exp = build1 (NOP_EXPR, build_pointer_type (type), exp);
441 exp = build2 (POINTER_PLUS_EXPR, TREE_TYPE (exp), exp,
442 fold_build1_loc (input_location,
443 NEGATE_EXPR, sizetype,
444 TYPE_SIZE_UNIT (TREE_TYPE (exp))));
445 exp = cp_build_indirect_ref (exp, RO_NULL, tf_warning_or_error);
446 initialize_handler_parm (decl, exp);
450 /* Call __cxa_end_catch at the end of processing the exception. */
451 push_eh_cleanup (type);
453 init = do_begin_catch ();
455 /* If there's no decl at all, then all we need to do is make sure
456 to tell the runtime that we've begun handling the exception. */
457 if (decl == NULL || decl == error_mark_node || init == error_mark_node)
458 finish_expr_stmt (init);
460 /* If the C++ object needs constructing, we need to do that before
461 calling __cxa_begin_catch, so that std::uncaught_exception gets
462 the right value during the copy constructor. */
463 else if (flag_use_cxa_get_exception_ptr
464 && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
466 exp = do_get_exception_ptr ();
467 initialize_handler_parm (decl, exp);
468 finish_expr_stmt (init);
471 /* Otherwise the type uses a bitwise copy, and we don't have to worry
472 about the value of std::uncaught_exception and therefore can do the
473 copy with the return value of __cxa_end_catch instead. */
476 tree init_type = type;
478 /* Pointers are passed by values, everything else by reference. */
479 if (!TYPE_PTR_P (type))
480 init_type = build_pointer_type (type);
481 if (init_type != TREE_TYPE (init))
482 init = build1 (NOP_EXPR, init_type, init);
483 exp = create_temporary_var (init_type);
484 DECL_REGISTER (exp) = 1;
485 cp_finish_decl (exp, init, /*init_const_expr=*/false,
486 NULL_TREE, LOOKUP_ONLYCONVERTING);
487 initialize_handler_parm (decl, exp);
494 /* Call this to end a catch block. Its responsible for emitting the
495 code to handle jumping back to the correct place, and for emitting
496 the label to jump to if this catch block didn't match. */
499 expand_end_catch_block (void)
504 /* The exception being handled is rethrown if control reaches the end of
505 a handler of the function-try-block of a constructor or destructor. */
506 if (in_function_try_handler
507 && (DECL_CONSTRUCTOR_P (current_function_decl)
508 || DECL_DESTRUCTOR_P (current_function_decl)))
509 finish_expr_stmt (build_throw (NULL_TREE));
513 begin_eh_spec_block (void)
515 tree r = build_stmt (input_location, EH_SPEC_BLOCK, NULL_TREE, NULL_TREE);
517 EH_SPEC_STMTS (r) = push_stmt_list ();
522 finish_eh_spec_block (tree raw_raises, tree eh_spec_block)
526 EH_SPEC_STMTS (eh_spec_block) = pop_stmt_list (EH_SPEC_STMTS (eh_spec_block));
528 /* Strip cv quals, etc, from the specification types. */
529 for (raises = NULL_TREE;
530 raw_raises && TREE_VALUE (raw_raises);
531 raw_raises = TREE_CHAIN (raw_raises))
533 tree type = prepare_eh_type (TREE_VALUE (raw_raises));
534 tree tinfo = eh_type_info (type);
537 raises = tree_cons (NULL_TREE, type, raises);
540 EH_SPEC_RAISES (eh_spec_block) = raises;
543 /* Return a pointer to a buffer for an exception object of type TYPE. */
546 do_allocate_exception (tree type)
550 fn = get_identifier ("__cxa_allocate_exception");
551 if (!get_global_value_if_present (fn, &fn))
553 /* Declare void *__cxa_allocate_exception(size_t) throw(). */
554 fn = declare_nothrow_library_fn (fn, ptr_type_node, size_type_node);
557 return cp_build_function_call (fn,
558 tree_cons (NULL_TREE, size_in_bytes (type),
560 tf_warning_or_error);
563 /* Call __cxa_free_exception from a cleanup. This is never invoked
564 directly, but see the comment for stabilize_throw_expr. */
567 do_free_exception (tree ptr)
571 fn = get_identifier ("__cxa_free_exception");
572 if (!get_global_value_if_present (fn, &fn))
574 /* Declare void __cxa_free_exception (void *) throw(). */
575 fn = declare_nothrow_library_fn (fn, void_type_node, ptr_type_node);
578 return cp_build_function_call (fn, tree_cons (NULL_TREE, ptr, NULL_TREE),
579 tf_warning_or_error);
582 /* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
583 Called from build_throw via walk_tree_without_duplicates. */
586 wrap_cleanups_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
587 void *data ATTRIBUTE_UNUSED)
592 /* Don't walk into types. */
598 if (TREE_CODE (exp) != TARGET_EXPR)
601 cleanup = TARGET_EXPR_CLEANUP (exp);
604 cleanup = build1 (MUST_NOT_THROW_EXPR, void_type_node, cleanup);
605 TARGET_EXPR_CLEANUP (exp) = cleanup;
608 /* Keep iterating. */
612 /* Build a throw expression. */
615 build_throw (tree exp)
619 if (exp == error_mark_node)
622 if (processing_template_decl)
625 current_function_returns_abnormally = 1;
626 return build_min (THROW_EXPR, void_type_node, exp);
629 if (exp == null_node)
630 warning (0, "throwing NULL, which has integral, not pointer type");
632 if (exp != NULL_TREE)
634 if (!is_admissible_throw_operand (exp))
635 return error_mark_node;
639 return error_mark_node;
641 if (exp && decl_is_java_type (TREE_TYPE (exp), 1))
643 tree fn = get_identifier ("_Jv_Throw");
644 if (!get_global_value_if_present (fn, &fn))
646 /* Declare void _Jv_Throw (void *). */
647 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
648 tmp = build_function_type (ptr_type_node, tmp);
649 fn = push_throw_library_fn (fn, tmp);
651 else if (really_overloaded_fn (fn))
653 error ("%qD should never be overloaded", fn);
654 return error_mark_node;
656 fn = OVL_CURRENT (fn);
657 exp = cp_build_function_call (fn, tree_cons (NULL_TREE, exp, NULL_TREE),
658 tf_warning_or_error);
667 tree temp_expr, allocate_expr;
670 /* The CLEANUP_TYPE is the internal type of a destructor. */
673 tmp = void_list_node;
674 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
675 tmp = build_function_type (void_type_node, tmp);
676 cleanup_type = build_pointer_type (tmp);
679 fn = get_identifier ("__cxa_throw");
680 if (!get_global_value_if_present (fn, &fn))
682 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
683 /* ??? Second argument is supposed to be "std::type_info*". */
684 tmp = void_list_node;
685 tmp = tree_cons (NULL_TREE, cleanup_type, tmp);
686 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
687 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
688 tmp = build_function_type (void_type_node, tmp);
689 fn = push_throw_library_fn (fn, tmp);
694 A throw-expression initializes a temporary object, the type
695 of which is determined by removing any top-level
696 cv-qualifiers from the static type of the operand of throw
697 and adjusting the type from "array of T" or "function return
698 T" to "pointer to T" or "pointer to function returning T"
700 temp_type = is_bitfield_expr_with_lowered_type (exp);
702 temp_type = type_decays_to (TREE_TYPE (exp));
704 /* OK, this is kind of wacky. The standard says that we call
705 terminate when the exception handling mechanism, after
706 completing evaluation of the expression to be thrown but
707 before the exception is caught (_except.throw_), calls a
708 user function that exits via an uncaught exception.
710 So we have to protect the actual initialization of the
711 exception object with terminate(), but evaluate the
712 expression first. Since there could be temps in the
713 expression, we need to handle that, too. We also expand
714 the call to __cxa_allocate_exception first (which doesn't
715 matter, since it can't throw). */
717 /* Allocate the space for the exception. */
718 allocate_expr = do_allocate_exception (temp_type);
719 allocate_expr = get_target_expr (allocate_expr);
720 ptr = TARGET_EXPR_SLOT (allocate_expr);
721 object = build_nop (build_pointer_type (temp_type), ptr);
722 object = cp_build_indirect_ref (object, RO_NULL, tf_warning_or_error);
724 elided = (TREE_CODE (exp) == TARGET_EXPR);
726 /* And initialize the exception object. */
727 if (CLASS_TYPE_P (temp_type))
729 int flags = LOOKUP_NORMAL | LOOKUP_ONLYCONVERTING;
730 VEC(tree,gc) *exp_vec;
732 /* Under C++0x [12.8/16 class.copy], a thrown lvalue is sometimes
733 treated as an rvalue for the purposes of overload resolution
734 to favor move constructors over copy constructors. */
735 if (/* Must be a local, automatic variable. */
736 TREE_CODE (exp) == VAR_DECL
737 && DECL_CONTEXT (exp) == current_function_decl
738 && ! TREE_STATIC (exp)
739 /* The variable must not have the `volatile' qualifier. */
740 && !(cp_type_quals (TREE_TYPE (exp)) & TYPE_QUAL_VOLATILE))
741 flags = flags | LOOKUP_PREFER_RVALUE;
743 /* Call the copy constructor. */
744 exp_vec = make_tree_vector_single (exp);
745 exp = (build_special_member_call
746 (object, complete_ctor_identifier, &exp_vec,
747 TREE_TYPE (object), flags, tf_warning_or_error));
748 release_tree_vector (exp_vec);
749 if (exp == error_mark_node)
751 error (" in thrown expression");
752 return error_mark_node;
757 tmp = decay_conversion (exp);
758 if (tmp == error_mark_node)
759 return error_mark_node;
760 exp = build2 (INIT_EXPR, temp_type, object, tmp);
763 /* Pre-evaluate the thrown expression first, since if we allocated
764 the space first we would have to deal with cleaning it up if
765 evaluating this expression throws.
767 The case where EXP the initializer is a cast or a function
768 returning a class is a bit of a grey area in the standard; it's
769 unclear whether or not it should be allowed to throw. We used to
770 say no, as that allowed us to optimize this case without worrying
771 about deallocating the exception object if it does. But that
772 conflicted with expectations (PR 13944) and the EDG compiler; now
773 we wrap the initialization in a TRY_CATCH_EXPR to call
774 do_free_exception rather than in a MUST_NOT_THROW_EXPR, for this
777 BUT: Issue 475 may do away with this inconsistency by removing the
778 terminate() in this situation.
780 Note that we don't check the return value from stabilize_init
781 because it will only return false in cases where elided is true,
782 and therefore we don't need to work around the failure to
784 temp_expr = NULL_TREE;
785 stabilize_init (exp, &temp_expr);
787 /* Wrap the initialization in a CLEANUP_POINT_EXPR so that cleanups
788 for temporaries within the initialization are run before the one
789 for the exception object, preserving LIFO order. */
790 exp = build1 (CLEANUP_POINT_EXPR, void_type_node, exp);
793 exp = build2 (TRY_CATCH_EXPR, void_type_node, exp,
794 do_free_exception (ptr));
796 exp = build1 (MUST_NOT_THROW_EXPR, void_type_node, exp);
798 /* Prepend the allocation. */
799 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), allocate_expr, exp);
802 /* Prepend the calculation of the throw expression. Also, force
803 any cleanups from the expression to be evaluated here so that
804 we don't have to do them during unwinding. But first wrap
805 them in MUST_NOT_THROW_EXPR, since they are run after the
806 exception object is initialized. */
807 cp_walk_tree_without_duplicates (&temp_expr, wrap_cleanups_r, 0);
808 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), temp_expr, exp);
809 exp = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (exp), exp);
812 throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object)));
814 if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (object)))
816 cleanup = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)),
817 complete_dtor_identifier, 0);
818 cleanup = BASELINK_FUNCTIONS (cleanup);
820 cxx_mark_addressable (cleanup);
821 /* Pretend it's a normal function. */
822 cleanup = build1 (ADDR_EXPR, cleanup_type, cleanup);
825 cleanup = build_int_cst (cleanup_type, 0);
827 tmp = tree_cons (NULL_TREE, cleanup, NULL_TREE);
828 tmp = tree_cons (NULL_TREE, throw_type, tmp);
829 tmp = tree_cons (NULL_TREE, ptr, tmp);
830 /* ??? Indicate that this function call throws throw_type. */
831 tmp = cp_build_function_call (fn, tmp, tf_warning_or_error);
833 /* Tack on the initialization stuff. */
834 exp = build2 (COMPOUND_EXPR, TREE_TYPE (tmp), exp, tmp);
838 /* Rethrow current exception. */
840 tree fn = get_identifier ("__cxa_rethrow");
841 if (!get_global_value_if_present (fn, &fn))
843 /* Declare void __cxa_rethrow (void). */
844 fn = push_throw_library_fn
845 (fn, build_function_type (void_type_node, void_list_node));
848 /* ??? Indicate that this function call allows exceptions of the type
849 of the enclosing catch block (if known). */
850 exp = cp_build_function_call (fn, NULL_TREE, tf_warning_or_error);
853 exp = build1 (THROW_EXPR, void_type_node, exp);
858 /* Make sure TYPE is complete, pointer to complete, reference to
859 complete, or pointer to cv void. Issue diagnostic on failure.
860 Return the zero on failure and nonzero on success. FROM can be
861 the expr or decl from whence TYPE came, if available. */
864 complete_ptr_ref_or_void_ptr_p (tree type, tree from)
868 /* Check complete. */
869 type = complete_type_or_else (type, from);
873 /* Or a pointer or ref to one, or cv void *. */
874 is_ptr = TREE_CODE (type) == POINTER_TYPE;
875 if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE)
877 tree core = TREE_TYPE (type);
879 if (is_ptr && VOID_TYPE_P (core))
881 else if (!complete_type_or_else (core, from))
887 /* Return truth-value if EXPRESSION is admissible in throw-expression,
888 i.e. if it is not of incomplete type or a pointer/reference to such
889 a type or of an abstract class type. */
892 is_admissible_throw_operand (tree expr)
894 tree type = TREE_TYPE (expr);
896 /* 15.1/4 [...] The type of the throw-expression shall not be an
897 incomplete type, or a pointer or a reference to an incomplete
898 type, other than void*, const void*, volatile void*, or
899 const volatile void*. Except for these restriction and the
900 restrictions on type matching mentioned in 15.3, the operand
901 of throw is treated exactly as a function argument in a call
902 (5.2.2) or the operand of a return statement. */
903 if (!complete_ptr_ref_or_void_ptr_p (type, expr))
906 /* 10.4/3 An abstract class shall not be used as a parameter type,
907 as a function return type or as type of an explicit
909 else if (CLASS_TYPE_P (type) && CLASSTYPE_PURE_VIRTUALS (type))
911 error ("expression %qE of abstract class type %qT cannot "
912 "be used in throw-expression", expr, type);
919 /* Returns nonzero if FN is a declaration of a standard C library
920 function which is known not to throw.
922 [lib.res.on.exception.handling]: None of the functions from the
923 Standard C library shall report an error by throwing an
924 exception, unless it calls a program-supplied function that
925 throws an exception. */
930 nothrow_libfn_p (const_tree fn)
935 && DECL_EXTERNAL (fn)
936 && DECL_NAMESPACE_SCOPE_P (fn)
937 && DECL_EXTERN_C_P (fn))
940 /* Can't be a C library function. */
943 /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME
944 unless the system headers are playing rename tricks, and if
945 they are, we don't want to be confused by them. */
947 return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id));
950 /* Returns nonzero if an exception of type FROM will be caught by a
951 handler for type TO, as per [except.handle]. */
954 can_convert_eh (tree to, tree from)
956 to = non_reference (to);
957 from = non_reference (from);
959 if (TREE_CODE (to) == POINTER_TYPE && TREE_CODE (from) == POINTER_TYPE)
962 from = TREE_TYPE (from);
964 if (! at_least_as_qualified_p (to, from))
967 if (TREE_CODE (to) == VOID_TYPE)
970 /* Else fall through. */
973 if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
974 && PUBLICLY_UNIQUELY_DERIVED_P (to, from))
980 /* Check whether any of the handlers in I are shadowed by another handler
981 accepting TYPE. Note that the shadowing may not be complete; even if
982 an exception of type B would be caught by a handler for A, there could
983 be a derived class C for which A is an ambiguous base but B is not, so
984 the handler for B would catch an exception of type C. */
987 check_handlers_1 (tree master, tree_stmt_iterator i)
989 tree type = TREE_TYPE (master);
991 for (; !tsi_end_p (i); tsi_next (&i))
993 tree handler = tsi_stmt (i);
994 if (TREE_TYPE (handler) && can_convert_eh (type, TREE_TYPE (handler)))
996 warning_at (EXPR_LOCATION (handler), 0,
997 "exception of type %qT will be caught",
998 TREE_TYPE (handler));
999 warning_at (EXPR_LOCATION (master), 0,
1000 " by earlier handler for %qT", type);
1006 /* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK. */
1009 check_handlers (tree handlers)
1011 tree_stmt_iterator i;
1013 /* If we don't have a STATEMENT_LIST, then we've just got one
1014 handler, and thus nothing to warn about. */
1015 if (TREE_CODE (handlers) != STATEMENT_LIST)
1018 i = tsi_start (handlers);
1022 tree handler = tsi_stmt (i);
1025 /* No more handlers; nothing to shadow. */
1028 if (TREE_TYPE (handler) == NULL_TREE)
1029 permerror (EXPR_LOCATION (handler), "%<...%>"
1030 " handler must be the last handler for its try block");
1032 check_handlers_1 (handler, i);