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 /* Let `cp_finish_decl' know that this initializer is ok. */
396 DECL_INITIAL (decl
) = error_mark_node
;
397 decl
= pushdecl (decl
);
400 cp_finish_decl (decl
, init
, 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
))
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 (MINUS_EXPR
, TREE_TYPE (exp
), exp
,
432 TYPE_SIZE_UNIT (TREE_TYPE (exp
)));
433 exp
= build_indirect_ref (exp
, NULL
);
434 initialize_handler_parm (decl
, exp
);
438 /* Call __cxa_end_catch at the end of processing the exception. */
439 push_eh_cleanup (type
);
441 /* If there's no decl at all, then all we need to do is make sure
442 to tell the runtime that we've begun handling the exception. */
444 finish_expr_stmt (do_begin_catch ());
446 /* If the C++ object needs constructing, we need to do that before
447 calling __cxa_begin_catch, so that std::uncaught_exception gets
448 the right value during the copy constructor. */
449 else if (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 exp
= create_temporary_var (ptr_type_node
);
463 DECL_REGISTER (exp
) = 1;
464 cp_finish_decl (exp
, init
, NULL_TREE
, LOOKUP_ONLYCONVERTING
);
465 finish_expr_stmt (build_modify_expr (exp
, INIT_EXPR
, init
));
466 initialize_handler_parm (decl
, exp
);
473 /* Call this to end a catch block. Its responsible for emitting the
474 code to handle jumping back to the correct place, and for emitting
475 the label to jump to if this catch block didn't match. */
478 expand_end_catch_block (void)
483 /* The exception being handled is rethrown if control reaches the end of
484 a handler of the function-try-block of a constructor or destructor. */
485 if (in_function_try_handler
486 && (DECL_CONSTRUCTOR_P (current_function_decl
)
487 || DECL_DESTRUCTOR_P (current_function_decl
)))
488 finish_expr_stmt (build_throw (NULL_TREE
));
492 begin_eh_spec_block (void)
494 tree r
= build_stmt (EH_SPEC_BLOCK
, NULL_TREE
, NULL_TREE
);
496 EH_SPEC_STMTS (r
) = push_stmt_list ();
501 finish_eh_spec_block (tree raw_raises
, tree eh_spec_block
)
505 EH_SPEC_STMTS (eh_spec_block
) = pop_stmt_list (EH_SPEC_STMTS (eh_spec_block
));
507 /* Strip cv quals, etc, from the specification types. */
508 for (raises
= NULL_TREE
;
509 raw_raises
&& TREE_VALUE (raw_raises
);
510 raw_raises
= TREE_CHAIN (raw_raises
))
512 tree type
= prepare_eh_type (TREE_VALUE (raw_raises
));
513 tree tinfo
= eh_type_info (type
);
516 raises
= tree_cons (NULL_TREE
, type
, raises
);
519 EH_SPEC_RAISES (eh_spec_block
) = raises
;
522 /* Return a pointer to a buffer for an exception object of type TYPE. */
525 do_allocate_exception (tree type
)
529 fn
= get_identifier ("__cxa_allocate_exception");
530 if (!get_global_value_if_present (fn
, &fn
))
532 /* Declare void *__cxa_allocate_exception(size_t). */
533 tree tmp
= tree_cons (NULL_TREE
, size_type_node
, void_list_node
);
534 fn
= push_library_fn (fn
, build_function_type (ptr_type_node
, tmp
));
537 return build_function_call (fn
, tree_cons (NULL_TREE
, size_in_bytes (type
),
541 /* Call __cxa_free_exception from a cleanup. This is never invoked
542 directly, but see the comment for stabilize_throw_expr. */
545 do_free_exception (tree ptr
)
549 fn
= get_identifier ("__cxa_free_exception");
550 if (!get_global_value_if_present (fn
, &fn
))
552 /* Declare void __cxa_free_exception (void *). */
553 fn
= push_void_library_fn (fn
, tree_cons (NULL_TREE
, ptr_type_node
,
557 return build_function_call (fn
, tree_cons (NULL_TREE
, ptr
, NULL_TREE
));
560 /* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
561 Called from build_throw via walk_tree_without_duplicates. */
564 wrap_cleanups_r (tree
*tp
, int *walk_subtrees ATTRIBUTE_UNUSED
,
565 void *data ATTRIBUTE_UNUSED
)
570 /* Don't walk into types. */
576 if (TREE_CODE (exp
) != TARGET_EXPR
)
579 cleanup
= TARGET_EXPR_CLEANUP (exp
);
582 cleanup
= build1 (MUST_NOT_THROW_EXPR
, void_type_node
, cleanup
);
583 TARGET_EXPR_CLEANUP (exp
) = cleanup
;
586 /* Keep iterating. */
590 /* Build a throw expression. */
593 build_throw (tree exp
)
597 if (exp
== error_mark_node
)
600 if (processing_template_decl
)
602 current_function_returns_abnormally
= 1;
603 return build_min (THROW_EXPR
, void_type_node
, exp
);
606 if (exp
== null_node
)
607 warning (0, "throwing NULL, which has integral, not pointer type");
609 if (exp
!= NULL_TREE
)
611 if (!is_admissible_throw_operand (exp
))
612 return error_mark_node
;
616 return error_mark_node
;
618 if (exp
&& decl_is_java_type (TREE_TYPE (exp
), 1))
620 tree fn
= get_identifier ("_Jv_Throw");
621 if (!get_global_value_if_present (fn
, &fn
))
623 /* Declare void _Jv_Throw (void *). */
624 tree tmp
= tree_cons (NULL_TREE
, ptr_type_node
, void_list_node
);
625 tmp
= build_function_type (ptr_type_node
, tmp
);
626 fn
= push_throw_library_fn (fn
, tmp
);
628 else if (really_overloaded_fn (fn
))
630 error ("%qD should never be overloaded", fn
);
631 return error_mark_node
;
633 fn
= OVL_CURRENT (fn
);
634 exp
= build_function_call (fn
, tree_cons (NULL_TREE
, exp
, NULL_TREE
));
642 tree temp_expr
, allocate_expr
;
645 /* The CLEANUP_TYPE is the internal type of a destructor. */
648 tmp
= void_list_node
;
649 tmp
= tree_cons (NULL_TREE
, ptr_type_node
, tmp
);
650 tmp
= build_function_type (void_type_node
, tmp
);
651 cleanup_type
= build_pointer_type (tmp
);
654 fn
= get_identifier ("__cxa_throw");
655 if (!get_global_value_if_present (fn
, &fn
))
657 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
658 /* ??? Second argument is supposed to be "std::type_info*". */
659 tmp
= void_list_node
;
660 tmp
= tree_cons (NULL_TREE
, cleanup_type
, tmp
);
661 tmp
= tree_cons (NULL_TREE
, ptr_type_node
, tmp
);
662 tmp
= tree_cons (NULL_TREE
, ptr_type_node
, tmp
);
663 tmp
= build_function_type (void_type_node
, tmp
);
664 fn
= push_throw_library_fn (fn
, tmp
);
667 /* throw expression */
668 /* First, decay it. */
669 exp
= decay_conversion (exp
);
671 /* OK, this is kind of wacky. The standard says that we call
672 terminate when the exception handling mechanism, after
673 completing evaluation of the expression to be thrown but
674 before the exception is caught (_except.throw_), calls a
675 user function that exits via an uncaught exception.
677 So we have to protect the actual initialization of the
678 exception object with terminate(), but evaluate the
679 expression first. Since there could be temps in the
680 expression, we need to handle that, too. We also expand
681 the call to __cxa_allocate_exception first (which doesn't
682 matter, since it can't throw). */
684 /* Allocate the space for the exception. */
685 allocate_expr
= do_allocate_exception (TREE_TYPE (exp
));
686 allocate_expr
= get_target_expr (allocate_expr
);
687 ptr
= TARGET_EXPR_SLOT (allocate_expr
);
688 object
= build1 (NOP_EXPR
, build_pointer_type (TREE_TYPE (exp
)), ptr
);
689 object
= build_indirect_ref (object
, NULL
);
691 elided
= (TREE_CODE (exp
) == TARGET_EXPR
);
693 /* And initialize the exception object. */
694 exp
= build_init (object
, exp
, LOOKUP_ONLYCONVERTING
);
695 if (exp
== error_mark_node
)
697 error (" in thrown expression");
698 return error_mark_node
;
701 /* Pre-evaluate the thrown expression first, since if we allocated
702 the space first we would have to deal with cleaning it up if
703 evaluating this expression throws.
705 The case where EXP the initializer is a cast or a function
706 returning a class is a bit of a grey area in the standard; it's
707 unclear whether or not it should be allowed to throw. We used to
708 say no, as that allowed us to optimize this case without worrying
709 about deallocating the exception object if it does. But that
710 conflicted with expectations (PR 13944) and the EDG compiler; now
711 we wrap the initialization in a TRY_CATCH_EXPR to call
712 do_free_exception rather than in a MUST_NOT_THROW_EXPR, for this
715 BUT: Issue 475 may do away with this inconsistency by removing the
716 terminate() in this situation.
718 Note that we don't check the return value from stabilize_init
719 because it will only return false in cases where elided is true,
720 and therefore we don't need to work around the failure to
722 temp_expr
= NULL_TREE
;
723 stabilize_init (exp
, &temp_expr
);
726 exp
= build2 (TRY_CATCH_EXPR
, void_type_node
, exp
,
727 do_free_exception (ptr
));
729 exp
= build1 (MUST_NOT_THROW_EXPR
, void_type_node
, exp
);
731 /* Prepend the allocation. */
732 exp
= build2 (COMPOUND_EXPR
, TREE_TYPE (exp
), allocate_expr
, exp
);
735 /* Prepend the calculation of the throw expression. Also, force
736 any cleanups from the expression to be evaluated here so that
737 we don't have to do them during unwinding. But first wrap
738 them in MUST_NOT_THROW_EXPR, since they are run after the
739 exception object is initialized. */
740 walk_tree_without_duplicates (&temp_expr
, wrap_cleanups_r
, 0);
741 exp
= build2 (COMPOUND_EXPR
, TREE_TYPE (exp
), temp_expr
, exp
);
742 exp
= build1 (CLEANUP_POINT_EXPR
, TREE_TYPE (exp
), exp
);
745 throw_type
= build_eh_type_type (prepare_eh_type (TREE_TYPE (object
)));
747 if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (object
)))
749 cleanup
= lookup_fnfields (TYPE_BINFO (TREE_TYPE (object
)),
750 complete_dtor_identifier
, 0);
751 cleanup
= BASELINK_FUNCTIONS (cleanup
);
753 cxx_mark_addressable (cleanup
);
754 /* Pretend it's a normal function. */
755 cleanup
= build1 (ADDR_EXPR
, cleanup_type
, cleanup
);
758 cleanup
= build_int_cst (cleanup_type
, 0);
760 tmp
= tree_cons (NULL_TREE
, cleanup
, NULL_TREE
);
761 tmp
= tree_cons (NULL_TREE
, throw_type
, tmp
);
762 tmp
= tree_cons (NULL_TREE
, ptr
, tmp
);
763 /* ??? Indicate that this function call throws throw_type. */
764 tmp
= build_function_call (fn
, tmp
);
766 /* Tack on the initialization stuff. */
767 exp
= build2 (COMPOUND_EXPR
, TREE_TYPE (tmp
), exp
, tmp
);
771 /* Rethrow current exception. */
773 tree fn
= get_identifier ("__cxa_rethrow");
774 if (!get_global_value_if_present (fn
, &fn
))
776 /* Declare void __cxa_rethrow (void). */
777 fn
= push_throw_library_fn
778 (fn
, build_function_type (void_type_node
, void_list_node
));
781 /* ??? Indicate that this function call allows exceptions of the type
782 of the enclosing catch block (if known). */
783 exp
= build_function_call (fn
, NULL_TREE
);
786 exp
= build1 (THROW_EXPR
, void_type_node
, exp
);
791 /* Make sure TYPE is complete, pointer to complete, reference to
792 complete, or pointer to cv void. Issue diagnostic on failure.
793 Return the zero on failure and nonzero on success. FROM can be
794 the expr or decl from whence TYPE came, if available. */
797 complete_ptr_ref_or_void_ptr_p (tree type
, tree from
)
801 /* Check complete. */
802 type
= complete_type_or_else (type
, from
);
806 /* Or a pointer or ref to one, or cv void *. */
807 is_ptr
= TREE_CODE (type
) == POINTER_TYPE
;
808 if (is_ptr
|| TREE_CODE (type
) == REFERENCE_TYPE
)
810 tree core
= TREE_TYPE (type
);
812 if (is_ptr
&& VOID_TYPE_P (core
))
814 else if (!complete_type_or_else (core
, from
))
820 /* Return truth-value if EXPRESSION is admissible in throw-expression,
821 i.e. if it is not of incomplete type or a pointer/reference to such
822 a type or of an abstract class type. */
825 is_admissible_throw_operand (tree expr
)
827 tree type
= TREE_TYPE (expr
);
829 /* 15.1/4 [...] The type of the throw-expression shall not be an
830 incomplete type, or a pointer or a reference to an incomplete
831 type, other than void*, const void*, volatile void*, or
832 const volatile void*. Except for these restriction and the
833 restrictions on type matching mentioned in 15.3, the operand
834 of throw is treated exactly as a function argument in a call
835 (5.2.2) or the operand of a return statement. */
836 if (!complete_ptr_ref_or_void_ptr_p (type
, expr
))
839 /* 10.4/3 An abstract class shall not be used as a parameter type,
840 as a function return type or as type of an explicit
842 else if (CLASS_TYPE_P (type
) && CLASSTYPE_PURE_VIRTUALS (type
))
844 error ("expression %qE of abstract class type %qT cannot "
845 "be used in throw-expression", expr
, type
);
852 /* Returns nonzero if FN is a declaration of a standard C library
853 function which is known not to throw.
855 [lib.res.on.exception.handling]: None of the functions from the
856 Standard C library shall report an error by throwing an
857 exception, unless it calls a program-supplied function that
858 throws an exception. */
863 nothrow_libfn_p (tree fn
)
868 && DECL_EXTERNAL (fn
)
869 && DECL_NAMESPACE_SCOPE_P (fn
)
870 && DECL_EXTERN_C_P (fn
))
873 /* Can't be a C library function. */
876 /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME
877 unless the system headers are playing rename tricks, and if
878 they are, we don't want to be confused by them. */
880 return !!libc_name_p (IDENTIFIER_POINTER (id
), IDENTIFIER_LENGTH (id
));
883 /* Returns nonzero if an exception of type FROM will be caught by a
884 handler for type TO, as per [except.handle]. */
887 can_convert_eh (tree to
, tree from
)
889 to
= non_reference (to
);
890 from
= non_reference (from
);
892 if (TREE_CODE (to
) == POINTER_TYPE
&& TREE_CODE (from
) == POINTER_TYPE
)
895 from
= TREE_TYPE (from
);
897 if (! at_least_as_qualified_p (to
, from
))
900 if (TREE_CODE (to
) == VOID_TYPE
)
903 /* Else fall through. */
906 if (CLASS_TYPE_P (to
) && CLASS_TYPE_P (from
)
907 && PUBLICLY_UNIQUELY_DERIVED_P (to
, from
))
913 /* Check whether any of the handlers in I are shadowed by another handler
914 accepting TYPE. Note that the shadowing may not be complete; even if
915 an exception of type B would be caught by a handler for A, there could
916 be a derived class C for which A is an ambiguous base but B is not, so
917 the handler for B would catch an exception of type C. */
920 check_handlers_1 (tree master
, tree_stmt_iterator i
)
922 tree type
= TREE_TYPE (master
);
924 for (; !tsi_end_p (i
); tsi_next (&i
))
926 tree handler
= tsi_stmt (i
);
927 if (TREE_TYPE (handler
) && can_convert_eh (type
, TREE_TYPE (handler
)))
929 warning (0, "%Hexception of type %qT will be caught",
930 EXPR_LOCUS (handler
), TREE_TYPE (handler
));
931 warning (0, "%H by earlier handler for %qT",
932 EXPR_LOCUS (master
), type
);
938 /* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK. */
941 check_handlers (tree handlers
)
943 tree_stmt_iterator i
;
945 /* If we don't have a STATEMENT_LIST, then we've just got one
946 handler, and thus nothing to warn about. */
947 if (TREE_CODE (handlers
) != STATEMENT_LIST
)
950 i
= tsi_start (handlers
);
954 tree handler
= tsi_stmt (i
);
957 /* No more handlers; nothing to shadow. */
960 if (TREE_TYPE (handler
) == NULL_TREE
)
961 pedwarn ("%H%<...%> handler must be the last handler for"
962 " its try block", EXPR_LOCUS (handler
));
964 check_handlers_1 (handler
, i
);