1 /* Handle exceptional things in C++.
2 Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
4 Contributed by Michael Tiemann <tiemann@cygnus.com>
5 Rewritten by Mike Stump <mrs@cygnus.com>, based upon an
6 initial re-implementation courtesy Tad Hunt.
8 This file is part of GCC.
10 GCC is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 2, or (at your option)
15 GCC is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
20 You should have received a copy of the GNU General Public License
21 along with GCC; see the file COPYING. If not, write to
22 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
23 Boston, MA 02110-1301, USA. */
28 #include "coretypes.h"
39 #include "tree-inline.h"
40 #include "tree-iterator.h"
43 static void push_eh_cleanup (tree);
44 static tree prepare_eh_type (tree);
45 static tree build_eh_type_type (tree);
46 static tree do_begin_catch (void);
47 static int dtor_nothrow (tree);
48 static tree do_end_catch (tree);
49 static bool decl_is_java_type (tree decl, int err);
50 static void initialize_handler_parm (tree, tree);
51 static tree do_allocate_exception (tree);
52 static tree wrap_cleanups_r (tree *, int *, void *);
53 static int complete_ptr_ref_or_void_ptr_p (tree, tree);
54 static bool is_admissible_throw_operand (tree);
55 static int can_convert_eh (tree, tree);
56 static tree cp_protect_cleanup_actions (void);
58 /* Sets up all the global eh stuff that needs to be initialized at the
59 start of compilation. */
62 init_exception_processing (void)
66 /* void std::terminate (); */
67 push_namespace (std_identifier);
68 tmp = build_function_type (void_type_node, void_list_node);
69 terminate_node = build_cp_library_fn_ptr ("terminate", tmp);
70 TREE_THIS_VOLATILE (terminate_node) = 1;
71 TREE_NOTHROW (terminate_node) = 1;
74 /* void __cxa_call_unexpected(void *); */
75 tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
76 tmp = build_function_type (void_type_node, tmp);
78 = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp);
80 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
81 ? "__gxx_personality_sj0"
82 : "__gxx_personality_v0");
83 if (targetm.arm_eabi_unwinder)
84 unwind_resume_libfunc = init_one_libfunc ("__cxa_end_cleanup");
86 default_init_unwind_resume_libfunc ();
88 lang_eh_runtime_type = build_eh_type_type;
89 lang_protect_cleanup_actions = &cp_protect_cleanup_actions;
92 /* Returns an expression to be executed if an unhandled exception is
93 propagated out of a cleanup region. */
96 cp_protect_cleanup_actions (void)
100 When the destruction of an object during stack unwinding exits
101 using an exception ... void terminate(); is called. */
102 return build_call_n (terminate_node, 0);
106 prepare_eh_type (tree type)
108 if (type == NULL_TREE)
110 if (type == error_mark_node)
111 return error_mark_node;
113 /* peel back references, so they match. */
114 type = non_reference (type);
116 /* Peel off cv qualifiers. */
117 type = TYPE_MAIN_VARIANT (type);
122 /* Return the type info for TYPE as used by EH machinery. */
124 eh_type_info (tree type)
128 if (type == NULL_TREE || type == error_mark_node)
131 if (decl_is_java_type (type, 0))
132 exp = build_java_class_ref (TREE_TYPE (type));
134 exp = get_tinfo_decl (type);
139 /* Build the address of a typeinfo decl for use in the runtime
140 matching field of the exception model. */
143 build_eh_type_type (tree type)
145 tree exp = eh_type_info (type);
152 return convert (ptr_type_node, build_address (exp));
158 return build0 (EXC_PTR_EXPR, ptr_type_node);
161 /* Build up a call to __cxa_get_exception_ptr so that we can build a
162 copy constructor for the thrown object. */
165 do_get_exception_ptr (void)
169 fn = get_identifier ("__cxa_get_exception_ptr");
170 if (!get_global_value_if_present (fn, &fn))
172 /* Declare void* __cxa_get_exception_ptr (void *). */
173 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
174 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
177 return build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
181 /* Build up a call to __cxa_begin_catch, to tell the runtime that the
182 exception has been handled. */
185 do_begin_catch (void)
189 fn = get_identifier ("__cxa_begin_catch");
190 if (!get_global_value_if_present (fn, &fn))
192 /* Declare void* __cxa_begin_catch (void *). */
193 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
194 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
197 return build_function_call (fn, tree_cons (NULL_TREE, build_exc_ptr (),
201 /* Returns nonzero if cleaning up an exception of type TYPE (which can be
202 NULL_TREE for a ... handler) will not throw an exception. */
205 dtor_nothrow (tree type)
207 if (type == NULL_TREE)
210 if (!CLASS_TYPE_P (type))
213 if (CLASSTYPE_LAZY_DESTRUCTOR (type))
214 lazily_declare_fn (sfk_destructor, type);
216 return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type));
219 /* Build up a call to __cxa_end_catch, to destroy the exception object
220 for the current catch block if no others are currently using it. */
223 do_end_catch (tree type)
227 fn = get_identifier ("__cxa_end_catch");
228 if (!get_global_value_if_present (fn, &fn))
230 /* Declare void __cxa_end_catch (). */
231 fn = push_void_library_fn (fn, void_list_node);
232 /* This can throw if the destructor for the exception throws. */
233 TREE_NOTHROW (fn) = 0;
236 cleanup = build_function_call (fn, NULL_TREE);
237 TREE_NOTHROW (cleanup) = dtor_nothrow (type);
242 /* This routine creates the cleanup for the current exception. */
245 push_eh_cleanup (tree type)
247 finish_decl_cleanup (NULL_TREE, do_end_catch (type));
250 /* Return nonzero value if DECL is a Java type suitable for catch or
254 decl_is_java_type (tree decl, int err)
256 bool r = (TREE_CODE (decl) == POINTER_TYPE
257 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
258 && TYPE_FOR_JAVA (TREE_TYPE (decl)));
262 if (TREE_CODE (decl) == REFERENCE_TYPE
263 && TREE_CODE (TREE_TYPE (decl)) == RECORD_TYPE
264 && TYPE_FOR_JAVA (TREE_TYPE (decl)))
266 /* Can't throw a reference. */
267 error ("type %qT is disallowed in Java %<throw%> or %<catch%>",
274 = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));
276 if (jthrow_node == NULL_TREE)
278 ("call to Java %<catch%> or %<throw%> with %<jthrowable%> undefined");
280 jthrow_node = TREE_TYPE (TREE_TYPE (jthrow_node));
282 if (! DERIVED_FROM_P (jthrow_node, TREE_TYPE (decl)))
284 /* Thrown object must be a Throwable. */
285 error ("type %qT is not derived from %<java::lang::Throwable%>",
294 /* Select the personality routine to be used for exception handling,
295 or issue an error if we need two different ones in the same
297 ??? At present eh_personality_libfunc is set to
298 __gxx_personality_(sj|v)0 in init_exception_processing - should it
299 be done here instead? */
301 choose_personality_routine (enum languages lang)
316 if (lang != lang_cplusplus)
321 if (lang != lang_java)
326 ; /* Proceed to language selection. */
337 eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
338 ? "__gcj_personality_sj0"
339 : "__gcj_personality_v0");
348 error ("mixing C++ and Java catches in a single translation unit");
352 /* Initialize the catch parameter DECL. */
355 initialize_handler_parm (tree decl, tree exp)
360 /* Make sure we mark the catch param as used, otherwise we'll get a
361 warning about an unused ((anonymous)). */
362 TREE_USED (decl) = 1;
364 /* Figure out the type that the initializer is. Pointers are returned
365 adjusted by value from __cxa_begin_catch. Others are returned by
367 init_type = TREE_TYPE (decl);
368 if (!POINTER_TYPE_P (init_type))
369 init_type = build_reference_type (init_type);
371 choose_personality_routine (decl_is_java_type (init_type, 0)
372 ? lang_java : lang_cplusplus);
374 /* Since pointers are passed by value, initialize a reference to
375 pointer catch parm with the address of the temporary. */
376 if (TREE_CODE (init_type) == REFERENCE_TYPE
377 && TYPE_PTR_P (TREE_TYPE (init_type)))
378 exp = build_unary_op (ADDR_EXPR, exp, 1);
380 exp = ocp_convert (init_type, exp, CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
382 init = convert_from_reference (exp);
384 /* If the constructor for the catch parm exits via an exception, we
385 must call terminate. See eh23.C. */
386 if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
388 /* Generate the copy constructor call directly so we can wrap it.
389 See also expand_default_init. */
390 init = ocp_convert (TREE_TYPE (decl), init,
391 CONV_IMPLICIT|CONV_FORCE_TEMP, 0);
392 init = build1 (MUST_NOT_THROW_EXPR, TREE_TYPE (init), init);
395 decl = pushdecl (decl);
397 start_decl_1 (decl, true);
398 cp_finish_decl (decl, init, /*init_const_expr_p=*/false, NULL_TREE,
399 LOOKUP_ONLYCONVERTING|DIRECT_BIND);
402 /* Call this to start a catch block. DECL is the catch parameter. */
405 expand_start_catch_block (tree decl)
413 /* Make sure this declaration is reasonable. */
414 if (decl && !complete_ptr_ref_or_void_ptr_p (TREE_TYPE (decl), NULL_TREE))
415 decl = error_mark_node;
418 type = prepare_eh_type (TREE_TYPE (decl));
422 if (decl && decl_is_java_type (type, 1))
424 /* Java only passes object via pointer and doesn't require
425 adjusting. The java object is immediately before the
426 generic exception header. */
427 exp = build_exc_ptr ();
428 exp = build1 (NOP_EXPR, build_pointer_type (type), exp);
429 exp = build2 (POINTER_PLUS_EXPR, TREE_TYPE (exp), exp,
430 fold_build1 (NEGATE_EXPR, sizetype,
431 TYPE_SIZE_UNIT (TREE_TYPE (exp))));
432 exp = build_indirect_ref (exp, NULL);
433 initialize_handler_parm (decl, exp);
437 /* Call __cxa_end_catch at the end of processing the exception. */
438 push_eh_cleanup (type);
440 /* If there's no decl at all, then all we need to do is make sure
441 to tell the runtime that we've begun handling the exception. */
442 if (decl == NULL || decl == error_mark_node)
443 finish_expr_stmt (do_begin_catch ());
445 /* If the C++ object needs constructing, we need to do that before
446 calling __cxa_begin_catch, so that std::uncaught_exception gets
447 the right value during the copy constructor. */
448 else if (flag_use_cxa_get_exception_ptr
449 && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
451 exp = do_get_exception_ptr ();
452 initialize_handler_parm (decl, exp);
453 finish_expr_stmt (do_begin_catch ());
456 /* Otherwise the type uses a bitwise copy, and we don't have to worry
457 about the value of std::uncaught_exception and therefore can do the
458 copy with the return value of __cxa_end_catch instead. */
461 tree init = do_begin_catch ();
462 tree init_type = type;
464 /* Pointers are passed by values, everything else by reference. */
465 if (!TYPE_PTR_P (type))
466 init_type = build_pointer_type (type);
467 if (init_type != TREE_TYPE (init))
468 init = build1 (NOP_EXPR, init_type, init);
469 exp = create_temporary_var (init_type);
470 DECL_REGISTER (exp) = 1;
471 cp_finish_decl (exp, init, /*init_const_expr=*/false,
472 NULL_TREE, LOOKUP_ONLYCONVERTING);
473 initialize_handler_parm (decl, exp);
480 /* Call this to end a catch block. Its responsible for emitting the
481 code to handle jumping back to the correct place, and for emitting
482 the label to jump to if this catch block didn't match. */
485 expand_end_catch_block (void)
490 /* The exception being handled is rethrown if control reaches the end of
491 a handler of the function-try-block of a constructor or destructor. */
492 if (in_function_try_handler
493 && (DECL_CONSTRUCTOR_P (current_function_decl)
494 || DECL_DESTRUCTOR_P (current_function_decl)))
495 finish_expr_stmt (build_throw (NULL_TREE));
499 begin_eh_spec_block (void)
501 tree r = build_stmt (EH_SPEC_BLOCK, NULL_TREE, NULL_TREE);
503 EH_SPEC_STMTS (r) = push_stmt_list ();
508 finish_eh_spec_block (tree raw_raises, tree eh_spec_block)
512 EH_SPEC_STMTS (eh_spec_block) = pop_stmt_list (EH_SPEC_STMTS (eh_spec_block));
514 /* Strip cv quals, etc, from the specification types. */
515 for (raises = NULL_TREE;
516 raw_raises && TREE_VALUE (raw_raises);
517 raw_raises = TREE_CHAIN (raw_raises))
519 tree type = prepare_eh_type (TREE_VALUE (raw_raises));
520 tree tinfo = eh_type_info (type);
523 raises = tree_cons (NULL_TREE, type, raises);
526 EH_SPEC_RAISES (eh_spec_block) = raises;
529 /* Return a pointer to a buffer for an exception object of type TYPE. */
532 do_allocate_exception (tree type)
536 fn = get_identifier ("__cxa_allocate_exception");
537 if (!get_global_value_if_present (fn, &fn))
539 /* Declare void *__cxa_allocate_exception(size_t). */
540 tree tmp = tree_cons (NULL_TREE, size_type_node, void_list_node);
541 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
544 return build_function_call (fn, tree_cons (NULL_TREE, size_in_bytes (type),
548 /* Call __cxa_free_exception from a cleanup. This is never invoked
549 directly, but see the comment for stabilize_throw_expr. */
552 do_free_exception (tree ptr)
556 fn = get_identifier ("__cxa_free_exception");
557 if (!get_global_value_if_present (fn, &fn))
559 /* Declare void __cxa_free_exception (void *). */
560 fn = push_void_library_fn (fn, tree_cons (NULL_TREE, ptr_type_node,
564 return build_function_call (fn, tree_cons (NULL_TREE, ptr, NULL_TREE));
567 /* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
568 Called from build_throw via walk_tree_without_duplicates. */
571 wrap_cleanups_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
572 void *data ATTRIBUTE_UNUSED)
577 /* Don't walk into types. */
583 if (TREE_CODE (exp) != TARGET_EXPR)
586 cleanup = TARGET_EXPR_CLEANUP (exp);
589 cleanup = build1 (MUST_NOT_THROW_EXPR, void_type_node, cleanup);
590 TARGET_EXPR_CLEANUP (exp) = cleanup;
593 /* Keep iterating. */
597 /* Build a throw expression. */
600 build_throw (tree exp)
604 if (exp == error_mark_node)
607 if (processing_template_decl)
610 current_function_returns_abnormally = 1;
611 return build_min (THROW_EXPR, void_type_node, exp);
614 if (exp == null_node)
615 warning (0, "throwing NULL, which has integral, not pointer type");
617 if (exp != NULL_TREE)
619 if (!is_admissible_throw_operand (exp))
620 return error_mark_node;
624 return error_mark_node;
626 if (exp && decl_is_java_type (TREE_TYPE (exp), 1))
628 tree fn = get_identifier ("_Jv_Throw");
629 if (!get_global_value_if_present (fn, &fn))
631 /* Declare void _Jv_Throw (void *). */
632 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
633 tmp = build_function_type (ptr_type_node, tmp);
634 fn = push_throw_library_fn (fn, tmp);
636 else if (really_overloaded_fn (fn))
638 error ("%qD should never be overloaded", fn);
639 return error_mark_node;
641 fn = OVL_CURRENT (fn);
642 exp = build_function_call (fn, tree_cons (NULL_TREE, exp, NULL_TREE));
651 tree temp_expr, allocate_expr;
654 /* The CLEANUP_TYPE is the internal type of a destructor. */
657 tmp = void_list_node;
658 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
659 tmp = build_function_type (void_type_node, tmp);
660 cleanup_type = build_pointer_type (tmp);
663 fn = get_identifier ("__cxa_throw");
664 if (!get_global_value_if_present (fn, &fn))
666 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
667 /* ??? Second argument is supposed to be "std::type_info*". */
668 tmp = void_list_node;
669 tmp = tree_cons (NULL_TREE, cleanup_type, tmp);
670 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
671 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
672 tmp = build_function_type (void_type_node, tmp);
673 fn = push_throw_library_fn (fn, tmp);
678 A throw-expression initializes a temporary object, the type
679 of which is determined by removing any top-level
680 cv-qualifiers from the static type of the operand of throw
681 and adjusting the type from "array of T" or "function return
682 T" to "pointer to T" or "pointer to function returning T"
684 temp_type = is_bitfield_expr_with_lowered_type (exp);
686 temp_type = type_decays_to (TYPE_MAIN_VARIANT (TREE_TYPE (exp)));
688 /* OK, this is kind of wacky. The standard says that we call
689 terminate when the exception handling mechanism, after
690 completing evaluation of the expression to be thrown but
691 before the exception is caught (_except.throw_), calls a
692 user function that exits via an uncaught exception.
694 So we have to protect the actual initialization of the
695 exception object with terminate(), but evaluate the
696 expression first. Since there could be temps in the
697 expression, we need to handle that, too. We also expand
698 the call to __cxa_allocate_exception first (which doesn't
699 matter, since it can't throw). */
701 /* Allocate the space for the exception. */
702 allocate_expr = do_allocate_exception (temp_type);
703 allocate_expr = get_target_expr (allocate_expr);
704 ptr = TARGET_EXPR_SLOT (allocate_expr);
705 object = build_nop (build_pointer_type (temp_type), ptr);
706 object = build_indirect_ref (object, NULL);
708 elided = (TREE_CODE (exp) == TARGET_EXPR);
710 /* And initialize the exception object. */
711 if (CLASS_TYPE_P (temp_type))
713 int flags = LOOKUP_NORMAL | LOOKUP_ONLYCONVERTING;
715 /* Under C++0x [12.8/16 class.copy], a thrown lvalue is sometimes
716 treated as an rvalue for the purposes of overload resolution
717 to favor move constructors over copy constructors. */
718 if (/* Must be a local, automatic variable. */
719 TREE_CODE (exp) == VAR_DECL
720 && DECL_CONTEXT (exp) == current_function_decl
721 && ! TREE_STATIC (exp)
722 /* The variable must not have the `volatile' qualifier. */
723 && !(cp_type_quals (TREE_TYPE (exp)) & TYPE_QUAL_VOLATILE))
724 flags = flags | LOOKUP_PREFER_RVALUE;
726 /* Call the copy constructor. */
727 exp = (build_special_member_call
728 (object, complete_ctor_identifier,
729 build_tree_list (NULL_TREE, exp),
732 if (exp == error_mark_node)
734 error (" in thrown expression");
735 return error_mark_node;
739 exp = build2 (INIT_EXPR, temp_type, object,
740 decay_conversion (exp));
742 /* Pre-evaluate the thrown expression first, since if we allocated
743 the space first we would have to deal with cleaning it up if
744 evaluating this expression throws.
746 The case where EXP the initializer is a cast or a function
747 returning a class is a bit of a grey area in the standard; it's
748 unclear whether or not it should be allowed to throw. We used to
749 say no, as that allowed us to optimize this case without worrying
750 about deallocating the exception object if it does. But that
751 conflicted with expectations (PR 13944) and the EDG compiler; now
752 we wrap the initialization in a TRY_CATCH_EXPR to call
753 do_free_exception rather than in a MUST_NOT_THROW_EXPR, for this
756 BUT: Issue 475 may do away with this inconsistency by removing the
757 terminate() in this situation.
759 Note that we don't check the return value from stabilize_init
760 because it will only return false in cases where elided is true,
761 and therefore we don't need to work around the failure to
763 temp_expr = NULL_TREE;
764 stabilize_init (exp, &temp_expr);
766 /* Wrap the initialization in a CLEANUP_POINT_EXPR so that cleanups
767 for temporaries within the initialization are run before the one
768 for the exception object, preserving LIFO order. */
769 exp = build1 (CLEANUP_POINT_EXPR, void_type_node, exp);
772 exp = build2 (TRY_CATCH_EXPR, void_type_node, exp,
773 do_free_exception (ptr));
775 exp = build1 (MUST_NOT_THROW_EXPR, void_type_node, exp);
777 /* Prepend the allocation. */
778 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), allocate_expr, exp);
781 /* Prepend the calculation of the throw expression. Also, force
782 any cleanups from the expression to be evaluated here so that
783 we don't have to do them during unwinding. But first wrap
784 them in MUST_NOT_THROW_EXPR, since they are run after the
785 exception object is initialized. */
786 walk_tree_without_duplicates (&temp_expr, wrap_cleanups_r, 0);
787 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), temp_expr, exp);
788 exp = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (exp), exp);
791 throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object)));
793 if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (object)))
795 cleanup = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)),
796 complete_dtor_identifier, 0);
797 cleanup = BASELINK_FUNCTIONS (cleanup);
799 cxx_mark_addressable (cleanup);
800 /* Pretend it's a normal function. */
801 cleanup = build1 (ADDR_EXPR, cleanup_type, cleanup);
804 cleanup = build_int_cst (cleanup_type, 0);
806 tmp = tree_cons (NULL_TREE, cleanup, NULL_TREE);
807 tmp = tree_cons (NULL_TREE, throw_type, tmp);
808 tmp = tree_cons (NULL_TREE, ptr, tmp);
809 /* ??? Indicate that this function call throws throw_type. */
810 tmp = build_function_call (fn, tmp);
812 /* Tack on the initialization stuff. */
813 exp = build2 (COMPOUND_EXPR, TREE_TYPE (tmp), exp, tmp);
817 /* Rethrow current exception. */
819 tree fn = get_identifier ("__cxa_rethrow");
820 if (!get_global_value_if_present (fn, &fn))
822 /* Declare void __cxa_rethrow (void). */
823 fn = push_throw_library_fn
824 (fn, build_function_type (void_type_node, void_list_node));
827 /* ??? Indicate that this function call allows exceptions of the type
828 of the enclosing catch block (if known). */
829 exp = build_function_call (fn, NULL_TREE);
832 exp = build1 (THROW_EXPR, void_type_node, exp);
837 /* Make sure TYPE is complete, pointer to complete, reference to
838 complete, or pointer to cv void. Issue diagnostic on failure.
839 Return the zero on failure and nonzero on success. FROM can be
840 the expr or decl from whence TYPE came, if available. */
843 complete_ptr_ref_or_void_ptr_p (tree type, tree from)
847 /* Check complete. */
848 type = complete_type_or_else (type, from);
852 /* Or a pointer or ref to one, or cv void *. */
853 is_ptr = TREE_CODE (type) == POINTER_TYPE;
854 if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE)
856 tree core = TREE_TYPE (type);
858 if (is_ptr && VOID_TYPE_P (core))
860 else if (!complete_type_or_else (core, from))
866 /* Return truth-value if EXPRESSION is admissible in throw-expression,
867 i.e. if it is not of incomplete type or a pointer/reference to such
868 a type or of an abstract class type. */
871 is_admissible_throw_operand (tree expr)
873 tree type = TREE_TYPE (expr);
875 /* 15.1/4 [...] The type of the throw-expression shall not be an
876 incomplete type, or a pointer or a reference to an incomplete
877 type, other than void*, const void*, volatile void*, or
878 const volatile void*. Except for these restriction and the
879 restrictions on type matching mentioned in 15.3, the operand
880 of throw is treated exactly as a function argument in a call
881 (5.2.2) or the operand of a return statement. */
882 if (!complete_ptr_ref_or_void_ptr_p (type, expr))
885 /* 10.4/3 An abstract class shall not be used as a parameter type,
886 as a function return type or as type of an explicit
888 else if (CLASS_TYPE_P (type) && CLASSTYPE_PURE_VIRTUALS (type))
890 error ("expression %qE of abstract class type %qT cannot "
891 "be used in throw-expression", expr, type);
898 /* Returns nonzero if FN is a declaration of a standard C library
899 function which is known not to throw.
901 [lib.res.on.exception.handling]: None of the functions from the
902 Standard C library shall report an error by throwing an
903 exception, unless it calls a program-supplied function that
904 throws an exception. */
909 nothrow_libfn_p (tree fn)
914 && DECL_EXTERNAL (fn)
915 && DECL_NAMESPACE_SCOPE_P (fn)
916 && DECL_EXTERN_C_P (fn))
919 /* Can't be a C library function. */
922 /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME
923 unless the system headers are playing rename tricks, and if
924 they are, we don't want to be confused by them. */
926 return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id));
929 /* Returns nonzero if an exception of type FROM will be caught by a
930 handler for type TO, as per [except.handle]. */
933 can_convert_eh (tree to, tree from)
935 to = non_reference (to);
936 from = non_reference (from);
938 if (TREE_CODE (to) == POINTER_TYPE && TREE_CODE (from) == POINTER_TYPE)
941 from = TREE_TYPE (from);
943 if (! at_least_as_qualified_p (to, from))
946 if (TREE_CODE (to) == VOID_TYPE)
949 /* Else fall through. */
952 if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
953 && PUBLICLY_UNIQUELY_DERIVED_P (to, from))
959 /* Check whether any of the handlers in I are shadowed by another handler
960 accepting TYPE. Note that the shadowing may not be complete; even if
961 an exception of type B would be caught by a handler for A, there could
962 be a derived class C for which A is an ambiguous base but B is not, so
963 the handler for B would catch an exception of type C. */
966 check_handlers_1 (tree master, tree_stmt_iterator i)
968 tree type = TREE_TYPE (master);
970 for (; !tsi_end_p (i); tsi_next (&i))
972 tree handler = tsi_stmt (i);
973 if (TREE_TYPE (handler) && can_convert_eh (type, TREE_TYPE (handler)))
975 warning (0, "%Hexception of type %qT will be caught",
976 EXPR_LOCUS (handler), TREE_TYPE (handler));
977 warning (0, "%H by earlier handler for %qT",
978 EXPR_LOCUS (master), type);
984 /* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK. */
987 check_handlers (tree handlers)
989 tree_stmt_iterator i;
991 /* If we don't have a STATEMENT_LIST, then we've just got one
992 handler, and thus nothing to warn about. */
993 if (TREE_CODE (handlers) != STATEMENT_LIST)
996 i = tsi_start (handlers);
1000 tree handler = tsi_stmt (i);
1003 /* No more handlers; nothing to shadow. */
1006 if (TREE_TYPE (handler) == NULL_TREE)
1007 pedwarn ("%H%<...%> handler must be the last handler for"
1008 " its try block", EXPR_LOCUS (handler));
1010 check_handlers_1 (handler, i);