1 /* Handle exceptional things in C++.
2 Copyright (C) 1989-2015 Free Software Foundation, Inc.
3 Contributed by Michael Tiemann <tiemann@cygnus.com>
4 Rewritten by Mike Stump <mrs@cygnus.com>, based upon an
5 initial re-implementation courtesy Tad Hunt.
7 This file is part of GCC.
9 GCC is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3, or (at your option)
14 GCC is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with GCC; see the file COPYING3. If not see
21 <http://www.gnu.org/licenses/>. */
26 #include "coretypes.h"
31 #include "double-int.h"
38 #include "stringpool.h"
39 #include "trans-mem.h"
43 #include "tree-inline.h"
44 #include "tree-iterator.h"
47 static void push_eh_cleanup (tree
);
48 static tree
prepare_eh_type (tree
);
49 static tree
do_begin_catch (void);
50 static int dtor_nothrow (tree
);
51 static tree
do_end_catch (tree
);
52 static bool decl_is_java_type (tree decl
, int err
);
53 static void initialize_handler_parm (tree
, tree
);
54 static tree
do_allocate_exception (tree
);
55 static tree
wrap_cleanups_r (tree
*, int *, void *);
56 static int complete_ptr_ref_or_void_ptr_p (tree
, tree
);
57 static bool is_admissible_throw_operand_or_catch_parameter (tree
, bool);
58 static int can_convert_eh (tree
, tree
);
60 /* Sets up all the global eh stuff that needs to be initialized at the
61 start of compilation. */
64 init_exception_processing (void)
68 /* void std::terminate (); */
69 push_namespace (std_identifier
);
70 tmp
= build_function_type_list (void_type_node
, NULL_TREE
);
71 terminate_node
= build_cp_library_fn_ptr ("terminate", tmp
,
72 ECF_NOTHROW
| ECF_NORETURN
);
73 TREE_THIS_VOLATILE (terminate_node
) = 1;
74 TREE_NOTHROW (terminate_node
) = 1;
77 /* void __cxa_call_unexpected(void *); */
78 tmp
= build_function_type_list (void_type_node
, ptr_type_node
, NULL_TREE
);
80 = push_throw_library_fn (get_identifier ("__cxa_call_unexpected"), tmp
);
83 /* Returns an expression to be executed if an unhandled exception is
84 propagated out of a cleanup region. */
87 cp_protect_cleanup_actions (void)
91 When the destruction of an object during stack unwinding exits
92 using an exception ... void terminate(); is called. */
93 return terminate_node
;
97 prepare_eh_type (tree type
)
99 if (type
== NULL_TREE
)
101 if (type
== error_mark_node
)
102 return error_mark_node
;
104 /* peel back references, so they match. */
105 type
= non_reference (type
);
107 /* Peel off cv qualifiers. */
108 type
= TYPE_MAIN_VARIANT (type
);
110 /* Functions and arrays decay to pointers. */
111 type
= type_decays_to (type
);
116 /* Return the type info for TYPE as used by EH machinery. */
118 eh_type_info (tree type
)
122 if (type
== NULL_TREE
|| type
== error_mark_node
)
125 if (decl_is_java_type (type
, 0))
126 exp
= build_java_class_ref (TREE_TYPE (type
));
128 exp
= get_tinfo_decl (type
);
133 /* Build the address of a typeinfo decl for use in the runtime
134 matching field of the exception model. */
137 build_eh_type_type (tree type
)
139 tree exp
= eh_type_info (type
);
146 return convert (ptr_type_node
, build_address (exp
));
152 return build_call_n (builtin_decl_explicit (BUILT_IN_EH_POINTER
),
153 1, integer_zero_node
);
156 /* Declare a function NAME, returning RETURN_TYPE, taking a single
157 parameter PARM_TYPE, with an empty exception specification.
159 Note that the C++ ABI document does not have a throw-specifier on
160 the routines declared below via this function. The declarations
161 are consistent with the actual implementations in libsupc++. */
164 declare_library_fn (tree name
, tree return_type
, tree parm_type
, int ecf_flags
)
166 return push_library_fn (name
, build_function_type_list (return_type
,
173 /* Build up a call to __cxa_get_exception_ptr so that we can build a
174 copy constructor for the thrown object. */
177 do_get_exception_ptr (void)
181 fn
= get_identifier ("__cxa_get_exception_ptr");
182 if (!get_global_value_if_present (fn
, &fn
))
184 /* Declare void* __cxa_get_exception_ptr (void *) throw(). */
185 fn
= declare_library_fn (fn
, ptr_type_node
, ptr_type_node
,
186 ECF_NOTHROW
| ECF_PURE
| ECF_LEAF
| ECF_TM_PURE
);
189 return cp_build_function_call_nary (fn
, tf_warning_or_error
,
190 build_exc_ptr (), NULL_TREE
);
193 /* Build up a call to __cxa_begin_catch, to tell the runtime that the
194 exception has been handled. */
197 do_begin_catch (void)
201 fn
= get_identifier ("__cxa_begin_catch");
202 if (!get_global_value_if_present (fn
, &fn
))
204 /* Declare void* __cxa_begin_catch (void *) throw(). */
205 fn
= declare_library_fn (fn
, ptr_type_node
, ptr_type_node
, ECF_NOTHROW
);
207 /* Create its transactional-memory equivalent. */
210 tree fn2
= get_identifier ("_ITM_cxa_begin_catch");
211 if (!get_global_value_if_present (fn2
, &fn2
))
212 fn2
= declare_library_fn (fn2
, ptr_type_node
,
213 ptr_type_node
, ECF_NOTHROW
| ECF_TM_PURE
);
214 record_tm_replacement (fn
, fn2
);
218 return cp_build_function_call_nary (fn
, tf_warning_or_error
,
219 build_exc_ptr (), NULL_TREE
);
222 /* Returns nonzero if cleaning up an exception of type TYPE (which can be
223 NULL_TREE for a ... handler) will not throw an exception. */
226 dtor_nothrow (tree type
)
228 if (type
== NULL_TREE
|| type
== error_mark_node
)
231 if (TYPE_HAS_TRIVIAL_DESTRUCTOR (type
))
234 if (CLASSTYPE_LAZY_DESTRUCTOR (type
))
235 lazily_declare_fn (sfk_destructor
, type
);
237 return TREE_NOTHROW (CLASSTYPE_DESTRUCTORS (type
));
240 /* Build up a call to __cxa_end_catch, to destroy the exception object
241 for the current catch block if no others are currently using it. */
244 do_end_catch (tree type
)
248 fn
= get_identifier ("__cxa_end_catch");
249 if (!get_global_value_if_present (fn
, &fn
))
251 /* Declare void __cxa_end_catch ().
252 This can throw if the destructor for the exception throws. */
253 fn
= push_void_library_fn (fn
, void_list_node
, 0);
255 /* Create its transactional-memory equivalent. */
258 tree fn2
= get_identifier ("_ITM_cxa_end_catch");
259 if (!get_global_value_if_present (fn2
, &fn2
))
260 fn2
= push_void_library_fn (fn2
, void_list_node
, ECF_TM_PURE
);
261 record_tm_replacement (fn
, fn2
);
265 cleanup
= cp_build_function_call_vec (fn
, NULL
, tf_warning_or_error
);
266 TREE_NOTHROW (cleanup
) = dtor_nothrow (type
);
271 /* This routine creates the cleanup for the current exception. */
274 push_eh_cleanup (tree type
)
276 finish_decl_cleanup (NULL_TREE
, do_end_catch (type
));
279 /* Return nonzero value if DECL is a Java type suitable for catch or
283 decl_is_java_type (tree decl
, int err
)
285 bool r
= (TYPE_PTR_P (decl
)
286 && TREE_CODE (TREE_TYPE (decl
)) == RECORD_TYPE
287 && TYPE_FOR_JAVA (TREE_TYPE (decl
)));
291 if (TREE_CODE (decl
) == REFERENCE_TYPE
292 && TREE_CODE (TREE_TYPE (decl
)) == RECORD_TYPE
293 && TYPE_FOR_JAVA (TREE_TYPE (decl
)))
295 /* Can't throw a reference. */
296 error ("type %qT is disallowed in Java %<throw%> or %<catch%>",
303 = IDENTIFIER_GLOBAL_VALUE (get_identifier ("jthrowable"));
305 if (jthrow_node
== NULL_TREE
)
308 "call to Java %<catch%> or %<throw%> with %<jthrowable%> undefined");
310 jthrow_node
= TREE_TYPE (TREE_TYPE (jthrow_node
));
312 if (! DERIVED_FROM_P (jthrow_node
, TREE_TYPE (decl
)))
314 /* Thrown object must be a Throwable. */
315 error ("type %qT is not derived from %<java::lang::Throwable%>",
324 /* Select the personality routine to be used for exception handling,
325 or issue an error if we need two different ones in the same
327 ??? At present DECL_FUNCTION_PERSONALITY is set via
328 LANG_HOOKS_EH_PERSONALITY. Should it be done here instead? */
330 choose_personality_routine (enum languages lang
)
345 if (lang
!= lang_cplusplus
)
350 if (lang
!= lang_java
)
355 ; /* Proceed to language selection. */
366 terminate_node
= builtin_decl_explicit (BUILT_IN_ABORT
);
367 pragma_java_exceptions
= true;
376 error ("mixing C++ and Java catches in a single translation unit");
380 /* Wrap EXPR in a MUST_NOT_THROW_EXPR expressing that EXPR must
381 not throw any exceptions if COND is true. A condition of
382 NULL_TREE is treated as 'true'. */
385 build_must_not_throw_expr (tree body
, tree cond
)
387 tree type
= body
? TREE_TYPE (body
) : void_type_node
;
389 if (!flag_exceptions
)
392 if (cond
&& !value_dependent_expression_p (cond
))
394 cond
= cxx_constant_value (cond
);
395 if (integer_zerop (cond
))
397 else if (integer_onep (cond
))
401 return build2 (MUST_NOT_THROW_EXPR
, type
, body
, cond
);
405 /* Initialize the catch parameter DECL. */
408 initialize_handler_parm (tree decl
, tree exp
)
413 /* Make sure we mark the catch param as used, otherwise we'll get a
414 warning about an unused ((anonymous)). */
415 TREE_USED (decl
) = 1;
416 DECL_READ_P (decl
) = 1;
418 /* Figure out the type that the initializer is. Pointers are returned
419 adjusted by value from __cxa_begin_catch. Others are returned by
421 init_type
= TREE_TYPE (decl
);
422 if (!POINTER_TYPE_P (init_type
))
423 init_type
= build_reference_type (init_type
);
425 choose_personality_routine (decl_is_java_type (init_type
, 0)
426 ? lang_java
: lang_cplusplus
);
428 /* Since pointers are passed by value, initialize a reference to
429 pointer catch parm with the address of the temporary. */
430 if (TREE_CODE (init_type
) == REFERENCE_TYPE
431 && TYPE_PTR_P (TREE_TYPE (init_type
)))
432 exp
= cp_build_addr_expr (exp
, tf_warning_or_error
);
434 exp
= ocp_convert (init_type
, exp
, CONV_IMPLICIT
|CONV_FORCE_TEMP
, 0,
435 tf_warning_or_error
);
437 init
= convert_from_reference (exp
);
439 /* If the constructor for the catch parm exits via an exception, we
440 must call terminate. See eh23.C. */
441 if (TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl
)))
443 /* Generate the copy constructor call directly so we can wrap it.
444 See also expand_default_init. */
445 init
= ocp_convert (TREE_TYPE (decl
), init
,
446 CONV_IMPLICIT
|CONV_FORCE_TEMP
, 0,
447 tf_warning_or_error
);
448 /* Force cleanups now to avoid nesting problems with the
449 MUST_NOT_THROW_EXPR. */
450 init
= fold_build_cleanup_point_expr (TREE_TYPE (init
), init
);
451 init
= build_must_not_throw_expr (init
, NULL_TREE
);
454 decl
= pushdecl (decl
);
456 start_decl_1 (decl
, true);
457 cp_finish_decl (decl
, init
, /*init_const_expr_p=*/false, NULL_TREE
,
458 LOOKUP_ONLYCONVERTING
|DIRECT_BIND
);
462 /* Routine to see if exception handling is turned on.
463 DO_WARN is nonzero if we want to inform the user that exception
464 handling is turned off.
466 This is used to ensure that -fexceptions has been specified if the
467 compiler tries to use any exception-specific functions. */
472 if (! flag_exceptions
)
474 static int warned
= 0;
477 error ("exception handling disabled, use -fexceptions to enable");
485 /* Call this to start a catch block. DECL is the catch parameter. */
488 expand_start_catch_block (tree decl
)
498 if (!is_admissible_throw_operand_or_catch_parameter (decl
, false))
499 decl
= error_mark_node
;
501 type
= prepare_eh_type (TREE_TYPE (decl
));
502 mark_used (eh_type_info (type
));
507 if (decl
&& decl_is_java_type (type
, 1))
509 /* Java only passes object via pointer and doesn't require
510 adjusting. The java object is immediately before the
511 generic exception header. */
512 exp
= build_exc_ptr ();
513 exp
= build1 (NOP_EXPR
, build_pointer_type (type
), exp
);
514 exp
= fold_build_pointer_plus (exp
,
515 fold_build1_loc (input_location
,
516 NEGATE_EXPR
, sizetype
,
517 TYPE_SIZE_UNIT (TREE_TYPE (exp
))));
518 exp
= cp_build_indirect_ref (exp
, RO_NULL
, tf_warning_or_error
);
519 initialize_handler_parm (decl
, exp
);
523 /* Call __cxa_end_catch at the end of processing the exception. */
524 push_eh_cleanup (type
);
526 init
= do_begin_catch ();
528 /* If there's no decl at all, then all we need to do is make sure
529 to tell the runtime that we've begun handling the exception. */
530 if (decl
== NULL
|| decl
== error_mark_node
|| init
== error_mark_node
)
531 finish_expr_stmt (init
);
533 /* If the C++ object needs constructing, we need to do that before
534 calling __cxa_begin_catch, so that std::uncaught_exception gets
535 the right value during the copy constructor. */
536 else if (flag_use_cxa_get_exception_ptr
537 && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (decl
)))
539 exp
= do_get_exception_ptr ();
540 initialize_handler_parm (decl
, exp
);
541 finish_expr_stmt (init
);
544 /* Otherwise the type uses a bitwise copy, and we don't have to worry
545 about the value of std::uncaught_exception and therefore can do the
546 copy with the return value of __cxa_end_catch instead. */
549 tree init_type
= type
;
551 /* Pointers are passed by values, everything else by reference. */
552 if (!TYPE_PTR_P (type
))
553 init_type
= build_pointer_type (type
);
554 if (init_type
!= TREE_TYPE (init
))
555 init
= build1 (NOP_EXPR
, init_type
, init
);
556 exp
= create_temporary_var (init_type
);
557 DECL_REGISTER (exp
) = 1;
558 cp_finish_decl (exp
, init
, /*init_const_expr=*/false,
559 NULL_TREE
, LOOKUP_ONLYCONVERTING
);
560 initialize_handler_parm (decl
, exp
);
567 /* Call this to end a catch block. Its responsible for emitting the
568 code to handle jumping back to the correct place, and for emitting
569 the label to jump to if this catch block didn't match. */
572 expand_end_catch_block (void)
577 /* The exception being handled is rethrown if control reaches the end of
578 a handler of the function-try-block of a constructor or destructor. */
579 if (in_function_try_handler
580 && (DECL_CONSTRUCTOR_P (current_function_decl
)
581 || DECL_DESTRUCTOR_P (current_function_decl
)))
582 finish_expr_stmt (build_throw (NULL_TREE
));
586 begin_eh_spec_block (void)
589 location_t spec_location
= DECL_SOURCE_LOCATION (current_function_decl
);
591 /* A noexcept specification (or throw() with -fnothrow-opt) is a
592 MUST_NOT_THROW_EXPR. */
593 if (TYPE_NOEXCEPT_P (TREE_TYPE (current_function_decl
)))
595 r
= build_stmt (spec_location
, MUST_NOT_THROW_EXPR
,
596 NULL_TREE
, NULL_TREE
);
597 TREE_SIDE_EFFECTS (r
) = 1;
600 r
= build_stmt (spec_location
, EH_SPEC_BLOCK
, NULL_TREE
, NULL_TREE
);
602 TREE_OPERAND (r
, 0) = push_stmt_list ();
607 finish_eh_spec_block (tree raw_raises
, tree eh_spec_block
)
611 TREE_OPERAND (eh_spec_block
, 0)
612 = pop_stmt_list (TREE_OPERAND (eh_spec_block
, 0));
614 if (TREE_CODE (eh_spec_block
) == MUST_NOT_THROW_EXPR
)
617 /* Strip cv quals, etc, from the specification types. */
618 for (raises
= NULL_TREE
;
619 raw_raises
&& TREE_VALUE (raw_raises
);
620 raw_raises
= TREE_CHAIN (raw_raises
))
622 tree type
= prepare_eh_type (TREE_VALUE (raw_raises
));
623 tree tinfo
= eh_type_info (type
);
626 raises
= tree_cons (NULL_TREE
, type
, raises
);
629 EH_SPEC_RAISES (eh_spec_block
) = raises
;
632 /* Return a pointer to a buffer for an exception object of type TYPE. */
635 do_allocate_exception (tree type
)
639 fn
= get_identifier ("__cxa_allocate_exception");
640 if (!get_global_value_if_present (fn
, &fn
))
642 /* Declare void *__cxa_allocate_exception(size_t) throw(). */
643 fn
= declare_library_fn (fn
, ptr_type_node
, size_type_node
,
644 ECF_NOTHROW
| ECF_MALLOC
);
648 tree fn2
= get_identifier ("_ITM_cxa_allocate_exception");
649 if (!get_global_value_if_present (fn2
, &fn2
))
650 fn2
= declare_library_fn (fn2
, ptr_type_node
,
652 ECF_NOTHROW
| ECF_MALLOC
| ECF_TM_PURE
);
653 record_tm_replacement (fn
, fn2
);
657 return cp_build_function_call_nary (fn
, tf_warning_or_error
,
658 size_in_bytes (type
), NULL_TREE
);
661 /* Call __cxa_free_exception from a cleanup. This is never invoked
662 directly, but see the comment for stabilize_throw_expr. */
665 do_free_exception (tree ptr
)
669 fn
= get_identifier ("__cxa_free_exception");
670 if (!get_global_value_if_present (fn
, &fn
))
672 /* Declare void __cxa_free_exception (void *) throw(). */
673 fn
= declare_library_fn (fn
, void_type_node
, ptr_type_node
,
674 ECF_NOTHROW
| ECF_LEAF
);
677 return cp_build_function_call_nary (fn
, tf_warning_or_error
, ptr
, NULL_TREE
);
680 /* Wrap all cleanups for TARGET_EXPRs in MUST_NOT_THROW_EXPR.
681 Called from build_throw via walk_tree_without_duplicates. */
684 wrap_cleanups_r (tree
*tp
, int *walk_subtrees
, void * /*data*/)
689 /* Don't walk into types. */
695 if (TREE_CODE (exp
) != TARGET_EXPR
)
698 cleanup
= TARGET_EXPR_CLEANUP (exp
);
701 cleanup
= build2 (MUST_NOT_THROW_EXPR
, void_type_node
, cleanup
,
703 TARGET_EXPR_CLEANUP (exp
) = cleanup
;
706 /* Keep iterating. */
710 /* Build a throw expression. */
713 build_throw (tree exp
)
717 if (exp
== error_mark_node
)
720 if (processing_template_decl
)
723 current_function_returns_abnormally
= 1;
724 exp
= build_min (THROW_EXPR
, void_type_node
, exp
);
725 SET_EXPR_LOCATION (exp
, input_location
);
729 if (exp
== null_node
)
730 warning (0, "throwing NULL, which has integral, not pointer type");
732 if (exp
!= NULL_TREE
)
734 if (!is_admissible_throw_operand_or_catch_parameter (exp
, true))
735 return error_mark_node
;
739 return error_mark_node
;
741 if (exp
&& decl_is_java_type (TREE_TYPE (exp
), 1))
743 tree fn
= get_identifier ("_Jv_Throw");
744 if (!get_global_value_if_present (fn
, &fn
))
746 /* Declare void _Jv_Throw (void *). */
748 tmp
= build_function_type_list (ptr_type_node
,
749 ptr_type_node
, NULL_TREE
);
750 fn
= push_throw_library_fn (fn
, tmp
);
752 else if (really_overloaded_fn (fn
))
754 error ("%qD should never be overloaded", fn
);
755 return error_mark_node
;
757 fn
= OVL_CURRENT (fn
);
758 exp
= cp_build_function_call_nary (fn
, tf_warning_or_error
,
770 /* The CLEANUP_TYPE is the internal type of a destructor. */
773 tmp
= build_function_type_list (void_type_node
,
774 ptr_type_node
, NULL_TREE
);
775 cleanup_type
= build_pointer_type (tmp
);
778 fn
= get_identifier ("__cxa_throw");
779 if (!get_global_value_if_present (fn
, &fn
))
781 /* Declare void __cxa_throw (void*, void*, void (*)(void*)). */
782 /* ??? Second argument is supposed to be "std::type_info*". */
783 tmp
= build_function_type_list (void_type_node
,
784 ptr_type_node
, ptr_type_node
,
785 cleanup_type
, NULL_TREE
);
786 fn
= push_throw_library_fn (fn
, tmp
);
790 tree fn2
= get_identifier ("_ITM_cxa_throw");
791 if (!get_global_value_if_present (fn2
, &fn2
))
792 fn2
= push_throw_library_fn (fn2
, tmp
);
793 apply_tm_attr (fn2
, get_identifier ("transaction_pure"));
794 record_tm_replacement (fn
, fn2
);
800 A throw-expression initializes a temporary object, the type
801 of which is determined by removing any top-level
802 cv-qualifiers from the static type of the operand of throw
803 and adjusting the type from "array of T" or "function return
804 T" to "pointer to T" or "pointer to function returning T"
806 temp_type
= is_bitfield_expr_with_lowered_type (exp
);
808 temp_type
= cv_unqualified (type_decays_to (TREE_TYPE (exp
)));
810 /* OK, this is kind of wacky. The standard says that we call
811 terminate when the exception handling mechanism, after
812 completing evaluation of the expression to be thrown but
813 before the exception is caught (_except.throw_), calls a
814 user function that exits via an uncaught exception.
816 So we have to protect the actual initialization of the
817 exception object with terminate(), but evaluate the
818 expression first. Since there could be temps in the
819 expression, we need to handle that, too. We also expand
820 the call to __cxa_allocate_exception first (which doesn't
821 matter, since it can't throw). */
823 /* Allocate the space for the exception. */
824 allocate_expr
= do_allocate_exception (temp_type
);
825 allocate_expr
= get_target_expr (allocate_expr
);
826 ptr
= TARGET_EXPR_SLOT (allocate_expr
);
827 TARGET_EXPR_CLEANUP (allocate_expr
) = do_free_exception (ptr
);
828 CLEANUP_EH_ONLY (allocate_expr
) = 1;
830 object
= build_nop (build_pointer_type (temp_type
), ptr
);
831 object
= cp_build_indirect_ref (object
, RO_NULL
, tf_warning_or_error
);
833 /* And initialize the exception object. */
834 if (CLASS_TYPE_P (temp_type
))
836 int flags
= LOOKUP_NORMAL
| LOOKUP_ONLYCONVERTING
;
837 vec
<tree
, va_gc
> *exp_vec
;
839 /* Under C++0x [12.8/16 class.copy], a thrown lvalue is sometimes
840 treated as an rvalue for the purposes of overload resolution
841 to favor move constructors over copy constructors. */
842 if (/* Must be a local, automatic variable. */
844 && DECL_CONTEXT (exp
) == current_function_decl
845 && ! TREE_STATIC (exp
)
846 /* The variable must not have the `volatile' qualifier. */
847 && !(cp_type_quals (TREE_TYPE (exp
)) & TYPE_QUAL_VOLATILE
))
848 flags
= flags
| LOOKUP_PREFER_RVALUE
;
850 /* Call the copy constructor. */
851 exp_vec
= make_tree_vector_single (exp
);
852 exp
= (build_special_member_call
853 (object
, complete_ctor_identifier
, &exp_vec
,
854 TREE_TYPE (object
), flags
, tf_warning_or_error
));
855 release_tree_vector (exp_vec
);
856 if (exp
== error_mark_node
)
858 error (" in thrown expression");
859 return error_mark_node
;
864 tmp
= decay_conversion (exp
, tf_warning_or_error
);
865 if (tmp
== error_mark_node
)
866 return error_mark_node
;
867 exp
= build2 (INIT_EXPR
, temp_type
, object
, tmp
);
870 /* Mark any cleanups from the initialization as MUST_NOT_THROW, since
871 they are run after the exception object is initialized. */
872 cp_walk_tree_without_duplicates (&exp
, wrap_cleanups_r
, 0);
874 /* Prepend the allocation. */
875 exp
= build2 (COMPOUND_EXPR
, TREE_TYPE (exp
), allocate_expr
, exp
);
877 /* Force all the cleanups to be evaluated here so that we don't have
878 to do them during unwinding. */
879 exp
= build1 (CLEANUP_POINT_EXPR
, void_type_node
, exp
);
881 throw_type
= build_eh_type_type (prepare_eh_type (TREE_TYPE (object
)));
884 if (type_build_dtor_call (TREE_TYPE (object
)))
886 tree fn
= lookup_fnfields (TYPE_BINFO (TREE_TYPE (object
)),
887 complete_dtor_identifier
, 0);
888 fn
= BASELINK_FUNCTIONS (fn
);
890 if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (object
)))
892 cxx_mark_addressable (fn
);
893 /* Pretend it's a normal function. */
894 cleanup
= build1 (ADDR_EXPR
, cleanup_type
, fn
);
897 if (cleanup
== NULL_TREE
)
898 cleanup
= build_int_cst (cleanup_type
, 0);
900 /* ??? Indicate that this function call throws throw_type. */
901 tmp
= cp_build_function_call_nary (fn
, tf_warning_or_error
,
902 ptr
, throw_type
, cleanup
, NULL_TREE
);
904 /* Tack on the initialization stuff. */
905 exp
= build2 (COMPOUND_EXPR
, TREE_TYPE (tmp
), exp
, tmp
);
909 /* Rethrow current exception. */
911 tree fn
= get_identifier ("__cxa_rethrow");
912 if (!get_global_value_if_present (fn
, &fn
))
914 /* Declare void __cxa_rethrow (void). */
915 fn
= push_throw_library_fn
916 (fn
, build_function_type_list (void_type_node
, NULL_TREE
));
920 apply_tm_attr (fn
, get_identifier ("transaction_pure"));
922 /* ??? Indicate that this function call allows exceptions of the type
923 of the enclosing catch block (if known). */
924 exp
= cp_build_function_call_vec (fn
, NULL
, tf_warning_or_error
);
927 exp
= build1 (THROW_EXPR
, void_type_node
, exp
);
928 SET_EXPR_LOCATION (exp
, input_location
);
933 /* Make sure TYPE is complete, pointer to complete, reference to
934 complete, or pointer to cv void. Issue diagnostic on failure.
935 Return the zero on failure and nonzero on success. FROM can be
936 the expr or decl from whence TYPE came, if available. */
939 complete_ptr_ref_or_void_ptr_p (tree type
, tree from
)
943 /* Check complete. */
944 type
= complete_type_or_else (type
, from
);
948 /* Or a pointer or ref to one, or cv void *. */
949 is_ptr
= TYPE_PTR_P (type
);
950 if (is_ptr
|| TREE_CODE (type
) == REFERENCE_TYPE
)
952 tree core
= TREE_TYPE (type
);
954 if (is_ptr
&& VOID_TYPE_P (core
))
956 else if (!complete_type_or_else (core
, from
))
962 /* If IS_THROW is true return truth-value if T is an expression admissible
963 in throw-expression, i.e. if it is not of incomplete type or a pointer/
964 reference to such a type or of an abstract class type.
965 If IS_THROW is false, likewise for a catch parameter, same requirements
966 for its type plus rvalue reference type is also not admissible. */
969 is_admissible_throw_operand_or_catch_parameter (tree t
, bool is_throw
)
971 tree expr
= is_throw
? t
: NULL_TREE
;
972 tree type
= TREE_TYPE (t
);
974 /* C++11 [except.handle] The exception-declaration shall not denote
975 an incomplete type, an abstract class type, or an rvalue reference
978 /* 15.1/4 [...] The type of the throw-expression shall not be an
979 incomplete type, or a pointer or a reference to an incomplete
980 type, other than void*, const void*, volatile void*, or
981 const volatile void*. Except for these restriction and the
982 restrictions on type matching mentioned in 15.3, the operand
983 of throw is treated exactly as a function argument in a call
984 (5.2.2) or the operand of a return statement. */
985 if (!complete_ptr_ref_or_void_ptr_p (type
, expr
))
988 /* 10.4/3 An abstract class shall not be used as a parameter type,
989 as a function return type or as type of an explicit
991 else if (abstract_virtuals_error (is_throw
? ACU_THROW
: ACU_CATCH
, type
))
994 && TREE_CODE (type
) == REFERENCE_TYPE
995 && TYPE_REF_IS_RVALUE (type
))
997 error ("cannot declare catch parameter to be of rvalue "
998 "reference type %qT", type
);
1001 else if (variably_modified_type_p (type
, NULL_TREE
))
1004 error ("cannot throw expression of type %qT because it involves "
1005 "types of variable size", type
);
1007 error ("cannot catch type %qT because it involves types of "
1008 "variable size", type
);
1015 /* Returns nonzero if FN is a declaration of a standard C library
1016 function which is known not to throw.
1018 [lib.res.on.exception.handling]: None of the functions from the
1019 Standard C library shall report an error by throwing an
1020 exception, unless it calls a program-supplied function that
1021 throws an exception. */
1026 nothrow_libfn_p (const_tree fn
)
1030 if (TREE_PUBLIC (fn
)
1031 && DECL_EXTERNAL (fn
)
1032 && DECL_NAMESPACE_SCOPE_P (fn
)
1033 && DECL_EXTERN_C_P (fn
))
1036 /* Can't be a C library function. */
1039 /* Being a C library function, DECL_ASSEMBLER_NAME == DECL_NAME
1040 unless the system headers are playing rename tricks, and if
1041 they are, we don't want to be confused by them. */
1042 id
= DECL_NAME (fn
);
1043 return !!libc_name_p (IDENTIFIER_POINTER (id
), IDENTIFIER_LENGTH (id
));
1046 /* Returns nonzero if an exception of type FROM will be caught by a
1047 handler for type TO, as per [except.handle]. */
1050 can_convert_eh (tree to
, tree from
)
1052 to
= non_reference (to
);
1053 from
= non_reference (from
);
1055 if (TYPE_PTR_P (to
) && TYPE_PTR_P (from
))
1057 to
= TREE_TYPE (to
);
1058 from
= TREE_TYPE (from
);
1060 if (! at_least_as_qualified_p (to
, from
))
1063 if (VOID_TYPE_P (to
))
1066 /* Else fall through. */
1069 if (CLASS_TYPE_P (to
) && CLASS_TYPE_P (from
)
1070 && publicly_uniquely_derived_p (to
, from
))
1076 /* Check whether any of the handlers in I are shadowed by another handler
1077 accepting TYPE. Note that the shadowing may not be complete; even if
1078 an exception of type B would be caught by a handler for A, there could
1079 be a derived class C for which A is an ambiguous base but B is not, so
1080 the handler for B would catch an exception of type C. */
1083 check_handlers_1 (tree master
, tree_stmt_iterator i
)
1085 tree type
= TREE_TYPE (master
);
1087 for (; !tsi_end_p (i
); tsi_next (&i
))
1089 tree handler
= tsi_stmt (i
);
1090 if (TREE_TYPE (handler
) && can_convert_eh (type
, TREE_TYPE (handler
)))
1092 warning_at (EXPR_LOCATION (handler
), 0,
1093 "exception of type %qT will be caught",
1094 TREE_TYPE (handler
));
1095 warning_at (EXPR_LOCATION (master
), 0,
1096 " by earlier handler for %qT", type
);
1102 /* Given a STATEMENT_LIST of HANDLERs, make sure that they're OK. */
1105 check_handlers (tree handlers
)
1107 tree_stmt_iterator i
;
1109 /* If we don't have a STATEMENT_LIST, then we've just got one
1110 handler, and thus nothing to warn about. */
1111 if (TREE_CODE (handlers
) != STATEMENT_LIST
)
1114 i
= tsi_start (handlers
);
1118 tree handler
= tsi_stmt (i
);
1121 /* No more handlers; nothing to shadow. */
1124 if (TREE_TYPE (handler
) == NULL_TREE
)
1125 permerror (EXPR_LOCATION (handler
), "%<...%>"
1126 " handler must be the last handler for its try block");
1128 check_handlers_1 (handler
, i
);
1132 /* walk_tree helper for finish_noexcept_expr. Returns non-null if the
1133 expression *TP causes the noexcept operator to evaluate to false.
1135 5.3.7 [expr.noexcept]: The result of the noexcept operator is false if
1136 in a potentially-evaluated context the expression would contain
1137 * a potentially evaluated call to a function, member function,
1138 function pointer, or member function pointer that does not have a
1139 non-throwing exception-specification (15.4),
1140 * a potentially evaluated throw-expression (15.1),
1141 * a potentially evaluated dynamic_cast expression dynamic_cast<T>(v),
1142 where T is a reference type, that requires a run-time check (5.2.7), or
1143 * a potentially evaluated typeid expression (5.2.8) applied to a glvalue
1144 expression whose type is a polymorphic class type (10.3). */
1147 check_noexcept_r (tree
*tp
, int * /*walk_subtrees*/, void * /*data*/)
1150 enum tree_code code
= TREE_CODE (t
);
1151 if (code
== CALL_EXPR
1152 || code
== AGGR_INIT_EXPR
)
1154 /* We can only use the exception specification of the called function
1155 for determining the value of a noexcept expression; we can't use
1156 TREE_NOTHROW, as it might have a different value in another
1157 translation unit, creating ODR problems.
1159 We could use TREE_NOTHROW (t) for !TREE_PUBLIC fns, though... */
1160 tree fn
= (code
== AGGR_INIT_EXPR
1161 ? AGGR_INIT_EXPR_FN (t
) : CALL_EXPR_FN (t
));
1162 tree type
= TREE_TYPE (TREE_TYPE (fn
));
1165 if (TREE_CODE (fn
) == ADDR_EXPR
)
1166 fn
= TREE_OPERAND (fn
, 0);
1167 if (TREE_CODE (fn
) == FUNCTION_DECL
)
1169 /* We do use TREE_NOTHROW for ABI internals like __dynamic_cast,
1170 and for C library functions known not to throw. */
1171 if (DECL_EXTERN_C_P (fn
)
1172 && (DECL_ARTIFICIAL (fn
)
1173 || nothrow_libfn_p (fn
)))
1174 return TREE_NOTHROW (fn
) ? NULL_TREE
: fn
;
1175 /* A call to a constexpr function is noexcept if the call
1176 is a constant expression. */
1177 if (DECL_DECLARED_CONSTEXPR_P (fn
)
1178 && is_sub_constant_expr (t
))
1181 if (!TYPE_NOTHROW_P (type
))
1188 /* If a function that causes a noexcept-expression to be false isn't
1189 defined yet, remember it and check it for TREE_NOTHROW again at EOF. */
1191 typedef struct GTY(()) pending_noexcept
{
1195 static GTY(()) vec
<pending_noexcept
, va_gc
> *pending_noexcept_checks
;
1197 /* FN is a FUNCTION_DECL that caused a noexcept-expr to be false. Warn if
1201 maybe_noexcept_warning (tree fn
)
1203 if (TREE_NOTHROW (fn
))
1205 warning (OPT_Wnoexcept
, "noexcept-expression evaluates to %<false%> "
1206 "because of a call to %qD", fn
);
1207 warning (OPT_Wnoexcept
, "but %q+D does not throw; perhaps "
1208 "it should be declared %<noexcept%>", fn
);
1212 /* Check any functions that weren't defined earlier when they caused a
1213 noexcept expression to evaluate to false. */
1216 perform_deferred_noexcept_checks (void)
1219 pending_noexcept
*p
;
1220 location_t saved_loc
= input_location
;
1221 FOR_EACH_VEC_SAFE_ELT (pending_noexcept_checks
, i
, p
)
1223 input_location
= p
->loc
;
1224 maybe_noexcept_warning (p
->fn
);
1226 input_location
= saved_loc
;
1229 /* Evaluate noexcept ( EXPR ). */
1232 finish_noexcept_expr (tree expr
, tsubst_flags_t complain
)
1234 if (expr
== error_mark_node
)
1235 return error_mark_node
;
1237 if (processing_template_decl
)
1238 return build_min (NOEXCEPT_EXPR
, boolean_type_node
, expr
);
1240 return (expr_noexcept_p (expr
, complain
)
1241 ? boolean_true_node
: boolean_false_node
);
1244 /* Returns whether EXPR is noexcept, possibly warning if allowed by
1248 expr_noexcept_p (tree expr
, tsubst_flags_t complain
)
1252 if (expr
== error_mark_node
)
1255 fn
= cp_walk_tree_without_duplicates (&expr
, check_noexcept_r
, 0);
1258 if ((complain
& tf_warning
) && warn_noexcept
1259 && TREE_CODE (fn
) == FUNCTION_DECL
)
1261 if (!DECL_INITIAL (fn
))
1263 /* Not defined yet; check again at EOF. */
1264 pending_noexcept p
= {fn
, input_location
};
1265 vec_safe_push (pending_noexcept_checks
, p
);
1268 maybe_noexcept_warning (fn
);
1276 /* Return true iff SPEC is throw() or noexcept(true). */
1279 nothrow_spec_p (const_tree spec
)
1281 gcc_assert (!DEFERRED_NOEXCEPT_SPEC_P (spec
));
1282 if (spec
== NULL_TREE
1283 || TREE_VALUE (spec
) != NULL_TREE
1284 || spec
== noexcept_false_spec
)
1286 if (TREE_PURPOSE (spec
) == NULL_TREE
1287 || spec
== noexcept_true_spec
)
1289 gcc_assert (processing_template_decl
1290 || TREE_PURPOSE (spec
) == error_mark_node
);
1294 /* For FUNCTION_TYPE or METHOD_TYPE, true if NODE is noexcept. This is the
1295 case for things declared noexcept(true) and, with -fnothrow-opt, for
1296 throw() functions. */
1299 type_noexcept_p (const_tree type
)
1301 tree spec
= TYPE_RAISES_EXCEPTIONS (type
);
1302 gcc_assert (!DEFERRED_NOEXCEPT_SPEC_P (spec
));
1303 if (flag_nothrow_opt
)
1304 return nothrow_spec_p (spec
);
1306 return spec
== noexcept_true_spec
;
1309 /* For FUNCTION_TYPE or METHOD_TYPE, true if NODE can throw any type,
1310 i.e. no exception-specification or noexcept(false). */
1313 type_throw_all_p (const_tree type
)
1315 tree spec
= TYPE_RAISES_EXCEPTIONS (type
);
1316 gcc_assert (!DEFERRED_NOEXCEPT_SPEC_P (spec
));
1317 return spec
== NULL_TREE
|| spec
== noexcept_false_spec
;
1320 /* Create a representation of the noexcept-specification with
1321 constant-expression of EXPR. COMPLAIN is as for tsubst. */
1324 build_noexcept_spec (tree expr
, int complain
)
1326 /* This isn't part of the signature, so don't bother trying to evaluate
1327 it until instantiation. */
1328 if (!processing_template_decl
&& TREE_CODE (expr
) != DEFERRED_NOEXCEPT
)
1330 expr
= perform_implicit_conversion_flags (boolean_type_node
, expr
,
1333 expr
= cxx_constant_value (expr
);
1335 if (TREE_CODE (expr
) == INTEGER_CST
)
1337 if (operand_equal_p (expr
, boolean_true_node
, 0))
1338 return noexcept_true_spec
;
1341 gcc_checking_assert (operand_equal_p (expr
, boolean_false_node
, 0));
1342 return noexcept_false_spec
;
1345 else if (expr
== error_mark_node
)
1346 return error_mark_node
;
1349 gcc_assert (processing_template_decl
1350 || TREE_CODE (expr
) == DEFERRED_NOEXCEPT
);
1351 return build_tree_list (expr
, NULL_TREE
);
1355 /* Returns a noexcept-specifier to be evaluated later, for an
1356 implicitly-declared or explicitly defaulted special member function. */
1359 unevaluated_noexcept_spec (void)
1362 if (spec
== NULL_TREE
)
1363 spec
= build_noexcept_spec (make_node (DEFERRED_NOEXCEPT
), tf_none
);
1367 /* Returns a TRY_CATCH_EXPR that will put TRY_LIST and CATCH_LIST in the
1368 TRY and CATCH locations. CATCH_LIST must be a STATEMENT_LIST */
1371 create_try_catch_expr (tree try_expr
, tree catch_list
)
1373 location_t loc
= EXPR_LOCATION (try_expr
);
1375 append_to_statement_list (do_begin_catch (), &catch_list
);
1376 append_to_statement_list (build_throw (NULL_TREE
), &catch_list
);
1377 tree catch_tf_expr
= build_stmt (loc
, TRY_FINALLY_EXPR
, catch_list
,
1378 do_end_catch (NULL_TREE
));
1379 catch_list
= build2 (CATCH_EXPR
, void_type_node
, NULL_TREE
,
1381 tree try_catch_expr
= build_stmt (loc
, TRY_CATCH_EXPR
, try_expr
, catch_list
);
1382 return try_catch_expr
;
1385 #include "gt-cp-except.h"