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 (terminate_node, NULL_TREE);
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 (MINUS_EXPR, TREE_TYPE (exp), exp,
430 TYPE_SIZE_UNIT (TREE_TYPE (exp)));
431 exp = build_indirect_ref (exp, NULL);
432 initialize_handler_parm (decl, exp);
436 /* Call __cxa_end_catch at the end of processing the exception. */
437 push_eh_cleanup (type);
439 /* If there's no decl at all, then all we need to do is make sure
440 to tell the runtime that we've begun handling the exception. */
441 if (decl == NULL || decl == error_mark_node)
442 finish_expr_stmt (do_begin_catch ());
444 /* If the C++ object needs constructing, we need to do that before
445 calling __cxa_begin_catch, so that std::uncaught_exception gets
446 the right value during the copy constructor. */
447 else if (flag_use_cxa_get_exception_ptr
448 && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl)))
450 exp = do_get_exception_ptr ();
451 initialize_handler_parm (decl, exp);
452 finish_expr_stmt (do_begin_catch ());
455 /* Otherwise the type uses a bitwise copy, and we don't have to worry
456 about the value of std::uncaught_exception and therefore can do the
457 copy with the return value of __cxa_end_catch instead. */
460 tree init = do_begin_catch ();
461 tree init_type = type;
463 /* Pointers are passed by values, everything else by reference. */
464 if (!TYPE_PTR_P (type))
465 init_type = build_pointer_type (type);
466 if (init_type != TREE_TYPE (init))
467 init = build1 (NOP_EXPR, init_type, init);
468 exp = create_temporary_var (init_type);
469 DECL_REGISTER (exp) = 1;
470 cp_finish_decl (exp, init, /*init_const_expr=*/false,
471 NULL_TREE, LOOKUP_ONLYCONVERTING);
472 initialize_handler_parm (decl, exp);
479 /* Call this to end a catch block. Its responsible for emitting the
480 code to handle jumping back to the correct place, and for emitting
481 the label to jump to if this catch block didn't match. */
484 expand_end_catch_block (void)
489 /* The exception being handled is rethrown if control reaches the end of
490 a handler of the function-try-block of a constructor or destructor. */
491 if (in_function_try_handler
492 && (DECL_CONSTRUCTOR_P (current_function_decl)
493 || DECL_DESTRUCTOR_P (current_function_decl)))
494 finish_expr_stmt (build_throw (NULL_TREE));
498 begin_eh_spec_block (void)
500 tree r = build_stmt (EH_SPEC_BLOCK, NULL_TREE, NULL_TREE);
502 EH_SPEC_STMTS (r) = push_stmt_list ();
507 finish_eh_spec_block (tree raw_raises, tree eh_spec_block)
511 EH_SPEC_STMTS (eh_spec_block) = pop_stmt_list (EH_SPEC_STMTS (eh_spec_block));
513 /* Strip cv quals, etc, from the specification types. */
514 for (raises = NULL_TREE;
515 raw_raises && TREE_VALUE (raw_raises);
516 raw_raises = TREE_CHAIN (raw_raises))
518 tree type = prepare_eh_type (TREE_VALUE (raw_raises));
519 tree tinfo = eh_type_info (type);
522 raises = tree_cons (NULL_TREE, type, raises);
525 EH_SPEC_RAISES (eh_spec_block) = raises;
528 /* Return a pointer to a buffer for an exception object of type TYPE. */
531 do_allocate_exception (tree type)
535 fn = get_identifier ("__cxa_allocate_exception");
536 if (!get_global_value_if_present (fn, &fn))
538 /* Declare void *__cxa_allocate_exception(size_t). */
539 tree tmp = tree_cons (NULL_TREE, size_type_node, void_list_node);
540 fn = push_library_fn (fn, build_function_type (ptr_type_node, tmp));
543 return build_function_call (fn, tree_cons (NULL_TREE, size_in_bytes (type),
547 /* Call __cxa_free_exception from a cleanup. This is never invoked
548 directly, but see the comment for stabilize_throw_expr. */
551 do_free_exception (tree ptr)
555 fn = get_identifier ("__cxa_free_exception");
556 if (!get_global_value_if_present (fn, &fn))
558 /* Declare void __cxa_free_exception (void *). */
559 fn = push_void_library_fn (fn, tree_cons (NULL_TREE, ptr_type_node,
563 return build_function_call (fn, tree_cons (NULL_TREE, ptr, NULL_TREE));
566 /* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
567 Called from build_throw via walk_tree_without_duplicates. */
570 wrap_cleanups_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
571 void *data ATTRIBUTE_UNUSED)
576 /* Don't walk into types. */
582 if (TREE_CODE (exp) != TARGET_EXPR)
585 cleanup = TARGET_EXPR_CLEANUP (exp);
588 cleanup = build1 (MUST_NOT_THROW_EXPR, void_type_node, cleanup);
589 TARGET_EXPR_CLEANUP (exp) = cleanup;
592 /* Keep iterating. */
596 /* Build a throw expression. */
599 build_throw (tree exp)
603 if (exp == error_mark_node)
606 if (processing_template_decl)
608 current_function_returns_abnormally = 1;
609 return build_min (THROW_EXPR, void_type_node, exp);
612 if (exp == null_node)
613 warning (0, "throwing NULL, which has integral, not pointer type");
615 if (exp != NULL_TREE)
617 if (!is_admissible_throw_operand (exp))
618 return error_mark_node;
622 return error_mark_node;
624 if (exp && decl_is_java_type (TREE_TYPE (exp), 1))
626 tree fn = get_identifier ("_Jv_Throw");
627 if (!get_global_value_if_present (fn, &fn))
629 /* Declare void _Jv_Throw (void *). */
630 tree tmp = tree_cons (NULL_TREE, ptr_type_node, void_list_node);
631 tmp = build_function_type (ptr_type_node, tmp);
632 fn = push_throw_library_fn (fn, tmp);
634 else if (really_overloaded_fn (fn))
636 error ("%qD should never be overloaded", fn);
637 return error_mark_node;
639 fn = OVL_CURRENT (fn);
640 exp = build_function_call (fn, tree_cons (NULL_TREE, exp, NULL_TREE));
649 tree temp_expr, allocate_expr;
652 /* The CLEANUP_TYPE is the internal type of a destructor. */
655 tmp = void_list_node;
656 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
657 tmp = build_function_type (void_type_node, tmp);
658 cleanup_type = build_pointer_type (tmp);
661 fn = get_identifier ("__cxa_throw");
662 if (!get_global_value_if_present (fn, &fn))
664 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
665 /* ??? Second argument is supposed to be "std::type_info*". */
666 tmp = void_list_node;
667 tmp = tree_cons (NULL_TREE, cleanup_type, tmp);
668 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
669 tmp = tree_cons (NULL_TREE, ptr_type_node, tmp);
670 tmp = build_function_type (void_type_node, tmp);
671 fn = push_throw_library_fn (fn, tmp);
676 A throw-expression initializes a temporary object, the type
677 of which is determined by removing any top-level
678 cv-qualifiers from the static type of the operand of throw
679 and adjusting the type from "array of T" or "function return
680 T" to "pointer to T" or "pointer to function returning T"
682 temp_type = is_bitfield_expr_with_lowered_type (exp);
684 temp_type = type_decays_to (TYPE_MAIN_VARIANT (TREE_TYPE (exp)));
686 /* OK, this is kind of wacky. The standard says that we call
687 terminate when the exception handling mechanism, after
688 completing evaluation of the expression to be thrown but
689 before the exception is caught (_except.throw_), calls a
690 user function that exits via an uncaught exception.
692 So we have to protect the actual initialization of the
693 exception object with terminate(), but evaluate the
694 expression first. Since there could be temps in the
695 expression, we need to handle that, too. We also expand
696 the call to __cxa_allocate_exception first (which doesn't
697 matter, since it can't throw). */
699 /* Allocate the space for the exception. */
700 allocate_expr = do_allocate_exception (temp_type);
701 allocate_expr = get_target_expr (allocate_expr);
702 ptr = TARGET_EXPR_SLOT (allocate_expr);
703 object = build_nop (build_pointer_type (temp_type), ptr);
704 object = build_indirect_ref (object, NULL);
706 elided = (TREE_CODE (exp) == TARGET_EXPR);
708 /* And initialize the exception object. */
709 if (CLASS_TYPE_P (temp_type))
711 /* Call the copy constructor. */
712 exp = (build_special_member_call
713 (object, complete_ctor_identifier,
714 build_tree_list (NULL_TREE, exp),
716 LOOKUP_NORMAL | LOOKUP_ONLYCONVERTING));
717 if (exp == error_mark_node)
719 error (" in thrown expression");
720 return error_mark_node;
724 exp = build2 (INIT_EXPR, temp_type, object,
725 decay_conversion (exp));
727 /* Pre-evaluate the thrown expression first, since if we allocated
728 the space first we would have to deal with cleaning it up if
729 evaluating this expression throws.
731 The case where EXP the initializer is a cast or a function
732 returning a class is a bit of a grey area in the standard; it's
733 unclear whether or not it should be allowed to throw. We used to
734 say no, as that allowed us to optimize this case without worrying
735 about deallocating the exception object if it does. But that
736 conflicted with expectations (PR 13944) and the EDG compiler; now
737 we wrap the initialization in a TRY_CATCH_EXPR to call
738 do_free_exception rather than in a MUST_NOT_THROW_EXPR, for this
741 BUT: Issue 475 may do away with this inconsistency by removing the
742 terminate() in this situation.
744 Note that we don't check the return value from stabilize_init
745 because it will only return false in cases where elided is true,
746 and therefore we don't need to work around the failure to
748 temp_expr = NULL_TREE;
749 stabilize_init (exp, &temp_expr);
751 /* Wrap the initialization in a CLEANUP_POINT_EXPR so that cleanups
752 for temporaries within the initialization are run before the one
753 for the exception object, preserving LIFO order. */
754 exp = build1 (CLEANUP_POINT_EXPR, void_type_node, exp);
757 exp = build2 (TRY_CATCH_EXPR, void_type_node, exp,
758 do_free_exception (ptr));
760 exp = build1 (MUST_NOT_THROW_EXPR, void_type_node, exp);
762 /* Prepend the allocation. */
763 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), allocate_expr, exp);
766 /* Prepend the calculation of the throw expression. Also, force
767 any cleanups from the expression to be evaluated here so that
768 we don't have to do them during unwinding. But first wrap
769 them in MUST_NOT_THROW_EXPR, since they are run after the
770 exception object is initialized. */
771 walk_tree_without_duplicates (&temp_expr, wrap_cleanups_r, 0);
772 exp = build2 (COMPOUND_EXPR, TREE_TYPE (exp), temp_expr, exp);
773 exp = build1 (CLEANUP_POINT_EXPR, TREE_TYPE (exp), exp);
776 throw_type = build_eh_type_type (prepare_eh_type (TREE_TYPE (object)));
778 if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (object)))
780 cleanup = lookup_fnfields (TYPE_BINFO (TREE_TYPE (object)),
781 complete_dtor_identifier, 0);
782 cleanup = BASELINK_FUNCTIONS (cleanup);
784 cxx_mark_addressable (cleanup);
785 /* Pretend it's a normal function. */
786 cleanup = build1 (ADDR_EXPR, cleanup_type, cleanup);
789 cleanup = build_int_cst (cleanup_type, 0);
791 tmp = tree_cons (NULL_TREE, cleanup, NULL_TREE);
792 tmp = tree_cons (NULL_TREE, throw_type, tmp);
793 tmp = tree_cons (NULL_TREE, ptr, tmp);
794 /* ??? Indicate that this function call throws throw_type. */
795 tmp = build_function_call (fn, tmp);
797 /* Tack on the initialization stuff. */
798 exp = build2 (COMPOUND_EXPR, TREE_TYPE (tmp), exp, tmp);
802 /* Rethrow current exception. */
804 tree fn = get_identifier ("__cxa_rethrow");
805 if (!get_global_value_if_present (fn, &fn))
807 /* Declare void __cxa_rethrow (void). */
808 fn = push_throw_library_fn
809 (fn, build_function_type (void_type_node, void_list_node));
812 /* ??? Indicate that this function call allows exceptions of the type
813 of the enclosing catch block (if known). */
814 exp = build_function_call (fn, NULL_TREE);
817 exp = build1 (THROW_EXPR, void_type_node, exp);
822 /* Make sure TYPE is complete, pointer to complete, reference to
823 complete, or pointer to cv void. Issue diagnostic on failure.
824 Return the zero on failure and nonzero on success. FROM can be
825 the expr or decl from whence TYPE came, if available. */
828 complete_ptr_ref_or_void_ptr_p (tree type, tree from)
832 /* Check complete. */
833 type = complete_type_or_else (type, from);
837 /* Or a pointer or ref to one, or cv void *. */
838 is_ptr = TREE_CODE (type) == POINTER_TYPE;
839 if (is_ptr || TREE_CODE (type) == REFERENCE_TYPE)
841 tree core = TREE_TYPE (type);
843 if (is_ptr && VOID_TYPE_P (core))
845 else if (!complete_type_or_else (core, from))
851 /* Return truth-value if EXPRESSION is admissible in throw-expression,
852 i.e. if it is not of incomplete type or a pointer/reference to such
853 a type or of an abstract class type. */
856 is_admissible_throw_operand (tree expr)
858 tree type = TREE_TYPE (expr);
860 /* 15.1/4 [...] The type of the throw-expression shall not be an
861 incomplete type, or a pointer or a reference to an incomplete
862 type, other than void*, const void*, volatile void*, or
863 const volatile void*. Except for these restriction and the
864 restrictions on type matching mentioned in 15.3, the operand
865 of throw is treated exactly as a function argument in a call
866 (5.2.2) or the operand of a return statement. */
867 if (!complete_ptr_ref_or_void_ptr_p (type, expr))
870 /* 10.4/3 An abstract class shall not be used as a parameter type,
871 as a function return type or as type of an explicit
873 else if (CLASS_TYPE_P (type) && CLASSTYPE_PURE_VIRTUALS (type))
875 error ("expression %qE of abstract class type %qT cannot "
876 "be used in throw-expression", expr, type);
883 /* Returns nonzero if FN is a declaration of a standard C library
884 function which is known not to throw.
886 [lib.res.on.exception.handling]: None of the functions from the
887 Standard C library shall report an error by throwing an
888 exception, unless it calls a program-supplied function that
889 throws an exception. */
894 nothrow_libfn_p (tree fn)
899 && DECL_EXTERNAL (fn)
900 && DECL_NAMESPACE_SCOPE_P (fn)
901 && DECL_EXTERN_C_P (fn))
904 /* Can't be a C library function. */
907 /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME
908 unless the system headers are playing rename tricks, and if
909 they are, we don't want to be confused by them. */
911 return !!libc_name_p (IDENTIFIER_POINTER (id), IDENTIFIER_LENGTH (id));
914 /* Returns nonzero if an exception of type FROM will be caught by a
915 handler for type TO, as per [except.handle]. */
918 can_convert_eh (tree to, tree from)
920 to = non_reference (to);
921 from = non_reference (from);
923 if (TREE_CODE (to) == POINTER_TYPE && TREE_CODE (from) == POINTER_TYPE)
926 from = TREE_TYPE (from);
928 if (! at_least_as_qualified_p (to, from))
931 if (TREE_CODE (to) == VOID_TYPE)
934 /* Else fall through. */
937 if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
938 && PUBLICLY_UNIQUELY_DERIVED_P (to, from))
944 /* Check whether any of the handlers in I are shadowed by another handler
945 accepting TYPE. Note that the shadowing may not be complete; even if
946 an exception of type B would be caught by a handler for A, there could
947 be a derived class C for which A is an ambiguous base but B is not, so
948 the handler for B would catch an exception of type C. */
951 check_handlers_1 (tree master, tree_stmt_iterator i)
953 tree type = TREE_TYPE (master);
955 for (; !tsi_end_p (i); tsi_next (&i))
957 tree handler = tsi_stmt (i);
958 if (TREE_TYPE (handler) && can_convert_eh (type, TREE_TYPE (handler)))
960 warning (0, "%Hexception of type %qT will be caught",
961 EXPR_LOCUS (handler), TREE_TYPE (handler));
962 warning (0, "%H by earlier handler for %qT",
963 EXPR_LOCUS (master), type);
969 /* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK. */
972 check_handlers (tree handlers)
974 tree_stmt_iterator i;
976 /* If we don't have a STATEMENT_LIST, then we've just got one
977 handler, and thus nothing to warn about. */
978 if (TREE_CODE (handlers) != STATEMENT_LIST)
981 i = tsi_start (handlers);
985 tree handler = tsi_stmt (i);
988 /* No more handlers; nothing to shadow. */
991 if (TREE_TYPE (handler) == NULL_TREE)
992 pedwarn ("%H%<...%> handler must be the last handler for"
993 " its try block", EXPR_LOCUS (handler));
995 check_handlers_1 (handler, i);