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 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 3, 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 COPYING3. If not see
22 <http://www.gnu.org/licenses/>. */
27 #include "coretypes.h"
38 #include "tree-inline.h"
39 #include "tree-iterator.h"
42 static void push_eh_cleanup (tree);
43 static tree prepare_eh_type (tree);
44 static tree build_eh_type_type (tree);
45 static tree do_begin_catch (void);
46 static int dtor_nothrow (tree);
47 static tree do_end_catch (tree);
48 static bool decl_is_java_type (tree decl, int err);
49 static void initialize_handler_parm (tree, tree);
50 static tree do_allocate_exception (tree);
51 static tree wrap_cleanups_r (tree *, int *, void *);
52 static int complete_ptr_ref_or_void_ptr_p (tree, tree);
53 static bool is_admissible_throw_operand (tree);
54 static int can_convert_eh (tree, tree);
55 static tree cp_protect_cleanup_actions (void);
57 /* Sets up all the global eh stuff that needs to be initialized at the
58 start of compilation. */
61 init_exception_processing (void)
65 /* void std::terminate (); */
66 push_namespace (std_identifier);
67 tmp = build_function_type (void_type_node, void_list_node);
68 terminate_node = build_cp_library_fn_ptr ("terminate", tmp);
69 TREE_THIS_VOLATILE (terminate_node) = 1;
70 TREE_NOTHROW (terminate_node) = 1;
73 /* void __cxa_call_unexpected(void *); */
74 tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
75 tmp = build_function_type (void_type_node, tmp);
77 = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp);
79 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
80 ? "__gxx_personality_sj0"
81 : "__gxx_personality_v0");
82 if (targetm.arm_eabi_unwinder)
83 unwind_resume_libfunc = init_one_libfunc ("__cxa_end_cleanup");
85 default_init_unwind_resume_libfunc ();
87 lang_eh_runtime_type = build_eh_type_type;
88 lang_protect_cleanup_actions = &cp_protect_cleanup_actions;
91 /* Returns an expression to be executed if an unhandled exception is
92 propagated out of a cleanup region. */
95 cp_protect_cleanup_actions (void)
99 When the destruction of an object during stack unwinding exits
100 using an exception ... void terminate(); is called. */
101 return build_call_n (terminate_node, 0);
105 prepare_eh_type (tree type)
107 if (type == NULL_TREE)
109 if (type == error_mark_node)
110 return error_mark_node;
112 /* peel back references, so they match. */
113 type = non_reference (type);
115 /* Peel off cv qualifiers. */
116 type = TYPE_MAIN_VARIANT (type);
121 /* Return the type info for TYPE as used by EH machinery. */
123 eh_type_info (tree type)
127 if (type == NULL_TREE || type == error_mark_node)
130 if (decl_is_java_type (type, 0))
131 exp = build_java_class_ref (TREE_TYPE (type));
133 exp = get_tinfo_decl (type);
138 /* Build the address of a typeinfo decl for use in the runtime
139 matching field of the exception model. */
142 build_eh_type_type (tree type)
144 tree exp = eh_type_info (type);
151 return convert (ptr_type_node, build_address (exp));
157 return build0 (EXC_PTR_EXPR, ptr_type_node);
160 /* Build up a call to __cxa_get_exception_ptr so that we can build a
161 copy constructor for the thrown object. */
164 do_get_exception_ptr (void)
168 fn = get_identifier ("__cxa_get_exception_ptr");
169 if (!get_global_value_if_present (fn, &fn))
171 /* Declare void* __cxa_get_exception_ptr (void *). */
172 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
173 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
176 return build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
180 /* Build up a call to __cxa_begin_catch, to tell the runtime that the
181 exception has been handled. */
184 do_begin_catch (void)
188 fn = get_identifier ("__cxa_begin_catch");
189 if (!get_global_value_if_present (fn, &fn))
191 /* Declare void* __cxa_begin_catch (void *). */
192 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
193 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
196 return build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
200 /* Returns nonzero if cleaning up an exception of type TYPE (which can be
201 NULL_TREE for a ... handler) will not throw an exception. */
204 dtor_nothrow (tree type)
206 if (type == NULL_TREE)
209 if (!CLASS_TYPE_P (type))
212 if (CLASSTYPE_LAZY_DESTRUCTOR (type))
213 lazily_declare_fn (sfk_destructor, type);
215 return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type));
218 /* Build up a call to __cxa_end_catch, to destroy the exception object
219 for the current catch block if no others are currently using it. */
222 do_end_catch (tree type)
226 fn = get_identifier ("__cxa_end_catch");
227 if (!get_global_value_if_present (fn, &fn))
229 /* Declare void __cxa_end_catch (). */
230 fn = push_void_library_fn (fn, void_list_node);
231 /* This can throw if the destructor for the exception throws. */
232 TREE_NOTHROW (fn) = 0;
235 cleanup = build_function_call (fn, NULL_TREE);
236 TREE_NOTHROW (cleanup) = dtor_nothrow (type);
241 /* This routine creates the cleanup for the current exception. */
244 push_eh_cleanup (tree type)
246 finish_decl_cleanup (NULL_TREE, do_end_catch (type));
249 /* Return nonzero value if DECL is a Java type suitable for catch or
253 decl_is_java_type (tree decl, int err)
255 bool r = (TREE_CODE (decl) == POINTER_TYPE
256 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
257 && TYPE_FOR_JAVA (TREE_TYPE (decl)));
261 if (TREE_CODE (decl) == REFERENCE_TYPE
262 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
263 && TYPE_FOR_JAVA (TREE_TYPE (decl)))
265 /* Can't throw a reference. */
266 error ("type %qT is disallowed in Java %<throw%> or %<catch%>",
273 = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));
275 if (jthrow_node == NULL_TREE)
277 ("call to Java %<catch%> or %<throw%> with %<jthrowable%> undefined");
279 jthrow_node = TREE_TYPE (TREE_TYPE (jthrow_node));
281 if (! DERIVED_FROM_P (jthrow_node, TREE_TYPE (decl)))
283 /* Thrown object must be a Throwable. */
284 error ("type %qT is not derived from %<java::lang::Throwable%>",
293 /* Select the personality routine to be used for exception handling,
294 or issue an error if we need two different ones in the same
296 ??? At present eh_personality_libfunc is set to
297 __gxx_personality_(sj|v)0 in init_exception_processing - should it
298 be done here instead? */
300 choose_personality_routine (enum languages lang)
315 if (lang != lang_cplusplus)
320 if (lang != lang_java)
325 ; /* Proceed to language selection. */
336 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
337 ? "__gcj_personality_sj0"
338 : "__gcj_personality_v0");
347 error ("mixing C++ and Java catches in a single translation unit");
351 /* Initialize the catch parameter DECL. */
354 initialize_handler_parm (tree decl, tree exp)
359 /* Make sure we mark the catch param as used, otherwise we'll get a
360 warning about an unused ((anonymous)). */
361 TREE_USED (decl) = 1;
363 /* Figure out the type that the initializer is. Pointers are returned
364 adjusted by value from __cxa_begin_catch. Others are returned by
366 init_type = TREE_TYPE (decl);
367 if (!POINTER_TYPE_P (init_type))
368 init_type = build_reference_type (init_type);
370 choose_personality_routine (decl_is_java_type (init_type, 0)
371 ? lang_java : lang_cplusplus);
373 /* Since pointers are passed by value, initialize a reference to
374 pointer catch parm with the address of the temporary. */
375 if (TREE_CODE (init_type) == REFERENCE_TYPE
376 && TYPE_PTR_P (TREE_TYPE (init_type)))
377 exp = build_unary_op (ADDR_EXPR, exp, 1);
379 exp = ocp_convert (init_type, exp, CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
381 init = convert_from_reference (exp);
383 /* If the constructor for the catch parm exits via an exception, we
384 must call terminate. See eh23.C. */
385 if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
387 /* Generate the copy constructor call directly so we can wrap it.
388 See also expand_default_init. */
389 init = ocp_convert (TREE_TYPE (decl), init,
390 CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
391 /* Force cleanups now to avoid nesting problems with the
392 MUST_NOT_THROW_EXPR. */
393 init = fold_build_cleanup_point_expr (TREE_TYPE (init), init);
394 init = build1 (MUST_NOT_THROW_EXPR, TREE_TYPE (init), init);
397 decl = pushdecl (decl);
399 start_decl_1 (decl, true);
400 cp_finish_decl (decl, init, /*init_const_expr_p=*/false, NULL_TREE,
401 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
404 /* Call this to start a catch block. DECL is the catch parameter. */
407 expand_start_catch_block (tree decl)
415 /* Make sure this declaration is reasonable. */
416 if (decl && !complete_ptr_ref_or_void_ptr_p (TREE_TYPE (decl), NULL_TREE))
417 decl = error_mark_node;
420 type = prepare_eh_type (TREE_TYPE (decl));
424 if (decl && decl_is_java_type (type, 1))
426 /* Java only passes object via pointer and doesn't require
427 adjusting. The java object is immediately before the
428 generic exception header. */
429 exp = build_exc_ptr ();
430 exp = build1 (NOP_EXPR, build_pointer_type (type), exp);
431 exp = build2 (POINTER_PLUS_EXPR, TREE_TYPE (exp), exp,
432 fold_build1 (NEGATE_EXPR, sizetype,
433 TYPE_SIZE_UNIT (TREE_TYPE (exp))));
434 exp = build_indirect_ref (exp, NULL);
435 initialize_handler_parm (decl, exp);
439 /* Call __cxa_end_catch at the end of processing the exception. */
440 push_eh_cleanup (type);
442 /* If there's no decl at all, then all we need to do is make sure
443 to tell the runtime that we've begun handling the exception. */
444 if (decl == NULL || decl == error_mark_node)
445 finish_expr_stmt (do_begin_catch ());
447 /* If the C++ object needs constructing, we need to do that before
448 calling __cxa_begin_catch, so that std::uncaught_exception gets
449 the right value during the copy constructor. */
450 else if (flag_use_cxa_get_exception_ptr
451 && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
453 exp = do_get_exception_ptr ();
454 initialize_handler_parm (decl, exp);
455 finish_expr_stmt (do_begin_catch ());
458 /* Otherwise the type uses a bitwise copy, and we don't have to worry
459 about the value of std::uncaught_exception and therefore can do the
460 copy with the return value of __cxa_end_catch instead. */
463 tree init = do_begin_catch ();
464 tree init_type = type;
466 /* Pointers are passed by values, everything else by reference. */
467 if (!TYPE_PTR_P (type))
468 init_type = build_pointer_type (type);
469 if (init_type != TREE_TYPE (init))
470 init = build1 (NOP_EXPR, init_type, init);
471 exp = create_temporary_var (init_type);
472 DECL_REGISTER (exp) = 1;
473 cp_finish_decl (exp, init, /*init_const_expr=*/false,
474 NULL_TREE, LOOKUP_ONLYCONVERTING);
475 initialize_handler_parm (decl, exp);
482 /* Call this to end a catch block. Its responsible for emitting the
483 code to handle jumping back to the correct place, and for emitting
484 the label to jump to if this catch block didn't match. */
487 expand_end_catch_block (void)
492 /* The exception being handled is rethrown if control reaches the end of
493 a handler of the function-try-block of a constructor or destructor. */
494 if (in_function_try_handler
495 && (DECL_CONSTRUCTOR_P (current_function_decl)
496 || DECL_DESTRUCTOR_P (current_function_decl)))
497 finish_expr_stmt (build_throw (NULL_TREE));
501 begin_eh_spec_block (void)
503 tree r = build_stmt (EH_SPEC_BLOCK, NULL_TREE, NULL_TREE);
505 EH_SPEC_STMTS (r) = push_stmt_list ();
510 finish_eh_spec_block (tree raw_raises, tree eh_spec_block)
514 EH_SPEC_STMTS (eh_spec_block) = pop_stmt_list (EH_SPEC_STMTS (eh_spec_block));
516 /* Strip cv quals, etc, from the specification types. */
517 for (raises = NULL_TREE;
518 raw_raises && TREE_VALUE (raw_raises);
519 raw_raises = TREE_CHAIN (raw_raises))
521 tree type = prepare_eh_type (TREE_VALUE (raw_raises));
522 tree tinfo = eh_type_info (type);
525 raises = tree_cons (NULL_TREE, type, raises);
528 EH_SPEC_RAISES (eh_spec_block) = raises;
531 /* Return a pointer to a buffer for an exception object of type TYPE. */
534 do_allocate_exception (tree type)
538 fn = get_identifier ("__cxa_allocate_exception");
539 if (!get_global_value_if_present (fn, &fn))
541 /* Declare void *__cxa_allocate_exception(size_t). */
542 tree tmp = tree_cons (NULL_TREE, size_type_node, void_list_node);
543 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
546 return build_function_call (fn, tree_cons (NULL_TREE, size_in_bytes (type),
550 /* Call __cxa_free_exception from a cleanup. This is never invoked
551 directly, but see the comment for stabilize_throw_expr. */
554 do_free_exception (tree ptr)
558 fn = get_identifier ("__cxa_free_exception");
559 if (!get_global_value_if_present (fn, &fn))
561 /* Declare void __cxa_free_exception (void *). */
562 fn = push_void_library_fn (fn, tree_cons (NULL_TREE, ptr_type_node,
566 return build_function_call (fn, tree_cons (NULL_TREE, ptr, NULL_TREE));
569 /* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
570 Called from build_throw via walk_tree_without_duplicates. */
573 wrap_cleanups_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
574 void *data ATTRIBUTE_UNUSED)
579 /* Don't walk into types. */
585 if (TREE_CODE (exp) != TARGET_EXPR)
588 cleanup = TARGET_EXPR_CLEANUP (exp);
591 cleanup = build1 (MUST_NOT_THROW_EXPR, void_type_node, cleanup);
592 TARGET_EXPR_CLEANUP (exp) = cleanup;
595 /* Keep iterating. */
599 /* Build a throw expression. */
602 build_throw (tree exp)
606 if (exp == error_mark_node)
609 if (processing_template_decl)
612 current_function_returns_abnormally = 1;
613 return build_min (THROW_EXPR, void_type_node, exp);
616 if (exp == null_node)
617 warning (0, "throwing NULL, which has integral, not pointer type");
619 if (exp != NULL_TREE)
621 if (!is_admissible_throw_operand (exp))
622 return error_mark_node;
626 return error_mark_node;
628 if (exp && decl_is_java_type (TREE_TYPE (exp), 1))
630 tree fn = get_identifier ("_Jv_Throw");
631 if (!get_global_value_if_present (fn, &fn))
633 /* Declare void _Jv_Throw (void *). */
634 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
635 tmp = build_function_type (ptr_type_node, tmp);
636 fn = push_throw_library_fn (fn, tmp);
638 else if (really_overloaded_fn (fn))
640 error ("%qD should never be overloaded", fn);
641 return error_mark_node;
643 fn = OVL_CURRENT (fn);
644 exp = build_function_call (fn, tree_cons (NULL_TREE, exp, NULL_TREE));
653 tree temp_expr, allocate_expr;
656 /* The CLEANUP_TYPE is the internal type of a destructor. */
659 tmp = void_list_node;
660 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
661 tmp = build_function_type (void_type_node, tmp);
662 cleanup_type = build_pointer_type (tmp);
665 fn = get_identifier ("__cxa_throw");
666 if (!get_global_value_if_present (fn, &fn))
668 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
669 /* ??? Second argument is supposed to be "std::type_info*". */
670 tmp = void_list_node;
671 tmp = tree_cons (NULL_TREE, cleanup_type, tmp);
672 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
673 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
674 tmp = build_function_type (void_type_node, tmp);
675 fn = push_throw_library_fn (fn, tmp);
680 A throw-expression initializes a temporary object, the type
681 of which is determined by removing any top-level
682 cv-qualifiers from the static type of the operand of throw
683 and adjusting the type from "array of T" or "function return
684 T" to "pointer to T" or "pointer to function returning T"
686 temp_type = is_bitfield_expr_with_lowered_type (exp);
688 temp_type = type_decays_to (TREE_TYPE (exp));
690 /* OK, this is kind of wacky. The standard says that we call
691 terminate when the exception handling mechanism, after
692 completing evaluation of the expression to be thrown but
693 before the exception is caught (_except.throw_), calls a
694 user function that exits via an uncaught exception.
696 So we have to protect the actual initialization of the
697 exception object with terminate(), but evaluate the
698 expression first. Since there could be temps in the
699 expression, we need to handle that, too. We also expand
700 the call to __cxa_allocate_exception first (which doesn't
701 matter, since it can't throw). */
703 /* Allocate the space for the exception. */
704 allocate_expr = do_allocate_exception (temp_type);
705 allocate_expr = get_target_expr (allocate_expr);
706 ptr = TARGET_EXPR_SLOT (allocate_expr);
707 object = build_nop (build_pointer_type (temp_type), ptr);
708 object = build_indirect_ref (object, NULL);
710 elided = (TREE_CODE (exp) == TARGET_EXPR);
712 /* And initialize the exception object. */
713 if (CLASS_TYPE_P (temp_type))
715 int flags = LOOKUP_NORMAL | LOOKUP_ONLYCONVERTING;
717 /* Under C++0x [12.8/16 class.copy], a thrown lvalue is sometimes
718 treated as an rvalue for the purposes of overload resolution
719 to favor move constructors over copy constructors. */
720 if (/* Must be a local, automatic variable. */
721 TREE_CODE (exp) == VAR_DECL
722 && DECL_CONTEXT (exp) == current_function_decl
723 && ! TREE_STATIC (exp)
724 /* The variable must not have the `volatile' qualifier. */
725 && !(cp_type_quals (TREE_TYPE (exp)) & TYPE_QUAL_VOLATILE))
726 flags = flags | LOOKUP_PREFER_RVALUE;
728 /* Call the copy constructor. */
729 exp = (build_special_member_call
730 (object, complete_ctor_identifier,
731 build_tree_list (NULL_TREE, exp),
734 if (exp == error_mark_node)
736 error (" in thrown expression");
737 return error_mark_node;
741 exp = build2 (INIT_EXPR, temp_type, object,
742 decay_conversion (exp));
744 /* Pre-evaluate the thrown expression first, since if we allocated
745 the space first we would have to deal with cleaning it up if
746 evaluating this expression throws.
748 The case where EXP the initializer is a cast or a function
749 returning a class is a bit of a grey area in the standard; it's
750 unclear whether or not it should be allowed to throw. We used to
751 say no, as that allowed us to optimize this case without worrying
752 about deallocating the exception object if it does. But that
753 conflicted with expectations (PR 13944) and the EDG compiler; now
754 we wrap the initialization in a TRY_CATCH_EXPR to call
755 do_free_exception rather than in a MUST_NOT_THROW_EXPR, for this
758 BUT: Issue 475 may do away with this inconsistency by removing the
759 terminate() in this situation.
761 Note that we don't check the return value from stabilize_init
762 because it will only return false in cases where elided is true,
763 and therefore we don't need to work around the failure to
765 temp_expr = NULL_TREE;
766 stabilize_init (exp, &temp_expr);
768 /* Wrap the initialization in a CLEANUP_POINT_EXPR so that cleanups
769 for temporaries within the initialization are run before the one
770 for the exception object, preserving LIFO order. */
771 exp = build1 (CLEANUP_POINT_EXPR, void_type_node, exp);
774 exp = build2 (TRY_CATCH_EXPR, void_type_node, exp,
775 do_free_exception (ptr));
777 exp = build1 (MUST_NOT_THROW_EXPR, void_type_node, exp);
779 /* Prepend the allocation. */
780 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), allocate_expr, exp);
783 /* Prepend the calculation of the throw expression. Also, force
784 any cleanups from the expression to be evaluated here so that
785 we don't have to do them during unwinding. But first wrap
786 them in MUST_NOT_THROW_EXPR, since they are run after the
787 exception object is initialized. */
788 cp_walk_tree_without_duplicates (&temp_expr, wrap_cleanups_r, 0);
789 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), temp_expr, exp);
790 exp = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (exp), exp);
793 throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object)));
795 if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (object)))
797 cleanup = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)),
798 complete_dtor_identifier, 0);
799 cleanup = BASELINK_FUNCTIONS (cleanup);
801 cxx_mark_addressable (cleanup);
802 /* Pretend it's a normal function. */
803 cleanup = build1 (ADDR_EXPR, cleanup_type, cleanup);
806 cleanup = build_int_cst (cleanup_type, 0);
808 tmp = tree_cons (NULL_TREE, cleanup, NULL_TREE);
809 tmp = tree_cons (NULL_TREE, throw_type, tmp);
810 tmp = tree_cons (NULL_TREE, ptr, tmp);
811 /* ??? Indicate that this function call throws throw_type. */
812 tmp = build_function_call (fn, tmp);
814 /* Tack on the initialization stuff. */
815 exp = build2 (COMPOUND_EXPR, TREE_TYPE (tmp), exp, tmp);
819 /* Rethrow current exception. */
821 tree fn = get_identifier ("__cxa_rethrow");
822 if (!get_global_value_if_present (fn, &fn))
824 /* Declare void __cxa_rethrow (void). */
825 fn = push_throw_library_fn
826 (fn, build_function_type (void_type_node, void_list_node));
829 /* ??? Indicate that this function call allows exceptions of the type
830 of the enclosing catch block (if known). */
831 exp = build_function_call (fn, NULL_TREE);
834 exp = build1 (THROW_EXPR, void_type_node, exp);
839 /* Make sure TYPE is complete, pointer to complete, reference to
840 complete, or pointer to cv void. Issue diagnostic on failure.
841 Return the zero on failure and nonzero on success. FROM can be
842 the expr or decl from whence TYPE came, if available. */
845 complete_ptr_ref_or_void_ptr_p (tree type, tree from)
849 /* Check complete. */
850 type = complete_type_or_else (type, from);
854 /* Or a pointer or ref to one, or cv void *. */
855 is_ptr = TREE_CODE (type) == POINTER_TYPE;
856 if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE)
858 tree core = TREE_TYPE (type);
860 if (is_ptr && VOID_TYPE_P (core))
862 else if (!complete_type_or_else (core, from))
868 /* Return truth-value if EXPRESSION is admissible in throw-expression,
869 i.e. if it is not of incomplete type or a pointer/reference to such
870 a type or of an abstract class type. */
873 is_admissible_throw_operand (tree expr)
875 tree type = TREE_TYPE (expr);
877 /* 15.1/4 [...] The type of the throw-expression shall not be an
878 incomplete type, or a pointer or a reference to an incomplete
879 type, other than void*, const void*, volatile void*, or
880 const volatile void*. Except for these restriction and the
881 restrictions on type matching mentioned in 15.3, the operand
882 of throw is treated exactly as a function argument in a call
883 (5.2.2) or the operand of a return statement. */
884 if (!complete_ptr_ref_or_void_ptr_p (type, expr))
887 /* 10.4/3 An abstract class shall not be used as a parameter type,
888 as a function return type or as type of an explicit
890 else if (CLASS_TYPE_P (type) && CLASSTYPE_PURE_VIRTUALS (type))
892 error ("expression %qE of abstract class type %qT cannot "
893 "be used in throw-expression", expr, type);
900 /* Returns nonzero if FN is a declaration of a standard C library
901 function which is known not to throw.
903 [lib.res.on.exception.handling]: None of the functions from the
904 Standard C library shall report an error by throwing an
905 exception, unless it calls a program-supplied function that
906 throws an exception. */
911 nothrow_libfn_p (const_tree fn)
916 && DECL_EXTERNAL (fn)
917 && DECL_NAMESPACE_SCOPE_P (fn)
918 && DECL_EXTERN_C_P (fn))
921 /* Can't be a C library function. */
924 /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME
925 unless the system headers are playing rename tricks, and if
926 they are, we don't want to be confused by them. */
928 return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id));
931 /* Returns nonzero if an exception of type FROM will be caught by a
932 handler for type TO, as per [except.handle]. */
935 can_convert_eh (tree to, tree from)
937 to = non_reference (to);
938 from = non_reference (from);
940 if (TREE_CODE (to) == POINTER_TYPE && TREE_CODE (from) == POINTER_TYPE)
943 from = TREE_TYPE (from);
945 if (! at_least_as_qualified_p (to, from))
948 if (TREE_CODE (to) == VOID_TYPE)
951 /* Else fall through. */
954 if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
955 && PUBLICLY_UNIQUELY_DERIVED_P (to, from))
961 /* Check whether any of the handlers in I are shadowed by another handler
962 accepting TYPE. Note that the shadowing may not be complete; even if
963 an exception of type B would be caught by a handler for A, there could
964 be a derived class C for which A is an ambiguous base but B is not, so
965 the handler for B would catch an exception of type C. */
968 check_handlers_1 (tree master, tree_stmt_iterator i)
970 tree type = TREE_TYPE (master);
972 for (; !tsi_end_p (i); tsi_next (&i))
974 tree handler = tsi_stmt (i);
975 if (TREE_TYPE (handler) && can_convert_eh (type, TREE_TYPE (handler)))
977 warning (0, "%Hexception of type %qT will be caught",
978 EXPR_LOCUS (handler), TREE_TYPE (handler));
979 warning (0, "%H by earlier handler for %qT",
980 EXPR_LOCUS (master), type);
986 /* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK. */
989 check_handlers (tree handlers)
991 tree_stmt_iterator i;
993 /* If we don't have a STATEMENT_LIST, then we've just got one
994 handler, and thus nothing to warn about. */
995 if (TREE_CODE (handlers) != STATEMENT_LIST)
998 i = tsi_start (handlers);
1002 tree handler = tsi_stmt (i);
1005 /* No more handlers; nothing to shadow. */
1008 if (TREE_TYPE (handler) == NULL_TREE)
1009 pedwarn ("%H%<...%> handler must be the last handler for"
1010 " its try block", EXPR_LOCUS (handler));
1012 check_handlers_1 (handler, i);