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Core 1402

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Core 1402
cp/
	* call.c (joust): An implicitly deleted move function is
	worse than any non-deleted function.
	* method.c (process_subob_fn): No special rules for move.
	(synthesized_method_walk, implicitly_declare_fn): Likewise.
	Warn about virtual base with non-trivial move assignment.
	* cp-tree.h (struct lang_decl_fn): Remove suppress_implicit_decl.
	(FNDECL_SUPPRESS_IMPLICIT_DECL): Remove.
c-family/
	* c.opt (Wvirtual-move-assign): New.

From-SVN: r192813
This commit is contained in:
Jason Merrill 2012-10-25 11:54:00 -04:00 committed by Jason Merrill
parent 57c3feb40a
commit f14edc1af5
10 changed files with 135 additions and 78 deletions
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2
gcc/c-family/ChangeLog
View File

@ -1,5 +1,7 @@
2012-10-25 Jason Merrill <jason@redhat.com>
* c.opt (Wvirtual-move-assign): New.
* c.opt (Winherited-variadic-ctor): New.
2012-10-25 Marc Glisse <marc.glisse@inria.fr>

4
gcc/c-family/c.opt
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@ -741,6 +741,10 @@ Wvolatile-register-var
C ObjC C++ ObjC++ Var(warn_volatile_register_var) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
Warn when a register variable is declared volatile
Wvirtual-move-assign
C++ ObjC++ Var(warn_virtual_move_assign) Warning Init(1)
Warn if a virtual base has a non-trivial move assignment operator
Wwrite-strings
C ObjC C++ ObjC++ Var(warn_write_strings) Warning
In C++, nonzero means warn about deprecated conversion from string literals to 'char *'. In C, similar warning, except that the conversion is of course not deprecated by the ISO C standard.

9
gcc/cp/ChangeLog
View File

@ -1,5 +1,14 @@
2012-10-25 Jason Merrill <jason@redhat.com>
Core 1402
* call.c (joust): An implicitly deleted move function is
worse than any non-deleted function.
* method.c (process_subob_fn): No special rules for move.
(synthesized_method_walk, implicitly_declare_fn): Likewise.
Warn about virtual base with non-trivial move assignment.
* cp-tree.h (struct lang_decl_fn): Remove suppress_implicit_decl.
(FNDECL_SUPPRESS_IMPLICIT_DECL): Remove.
* semantics.c (finish_omp_threadprivate): Call complete_type.
* class.c (one_inherited_ctor): Warn about variadic inherited ctor.

16
gcc/cp/call.c
View File

@ -8246,6 +8246,22 @@ joust (struct z_candidate *cand1, struct z_candidate *cand2, bool warn,
&& (IS_TYPE_OR_DECL_P (cand1->fn)))
return 1;
/* Prefer a non-deleted function over an implicitly deleted move
constructor or assignment operator. This differs slightly from the
wording for issue 1402 (which says the move op is ignored by overload
resolution), but this way produces better error messages. */
if (TREE_CODE (cand1->fn) == FUNCTION_DECL
&& TREE_CODE (cand2->fn) == FUNCTION_DECL
&& DECL_DELETED_FN (cand1->fn) != DECL_DELETED_FN (cand2->fn))
{
if (DECL_DELETED_FN (cand1->fn) && DECL_DEFAULTED_FN (cand1->fn)
&& move_fn_p (cand1->fn))
return -1;
if (DECL_DELETED_FN (cand2->fn) && DECL_DEFAULTED_FN (cand2->fn)
&& move_fn_p (cand2->fn))
return 1;
}
/* a viable function F1
is defined to be a better function than another viable function F2 if
for all arguments i, ICSi(F1) is not a worse conversion sequence than

8
gcc/cp/cp-tree.h
View File

@ -1954,7 +1954,7 @@ struct GTY(()) lang_decl_fn {
unsigned thunk_p : 1;
unsigned this_thunk_p : 1;
unsigned hidden_friend_p : 1;
unsigned suppress_implicit_decl : 1;
/* 1 spare bit. */
/* For a non-thunk function decl, this is a tree list of
friendly classes. For a thunk function decl, it is the
@ -3144,12 +3144,6 @@ more_aggr_init_expr_args_p (const aggr_init_expr_arg_iterator *iter)
#define DECL_HIDDEN_FRIEND_P(NODE) \
(LANG_DECL_FN_CHECK (DECL_COMMON_CHECK (NODE))->hidden_friend_p)
/* Nonzero if NODE is a FUNCTION_DECL generated by implicitly_declare_fn
that we shouldn't actually declare implicitly; it is only used for
comparing to an =default declaration. */
#define FNDECL_SUPPRESS_IMPLICIT_DECL(NODE) \
(LANG_DECL_FN_CHECK (DECL_COMMON_CHECK (NODE))->suppress_implicit_decl)
/* Nonzero if DECL has been declared threadprivate by
#pragma omp threadprivate. */
#define CP_DECL_THREADPRIVATE_P(DECL) \

108
gcc/cp/method.c
View File

@ -969,8 +969,8 @@ get_copy_assign (tree type)
DELETED_P or give an error message MSG with argument ARG. */
static void
process_subob_fn (tree fn, bool move_p, tree *spec_p, bool *trivial_p,
bool *deleted_p, bool *constexpr_p, bool *no_implicit_p,
process_subob_fn (tree fn, tree *spec_p, bool *trivial_p,
bool *deleted_p, bool *constexpr_p,
bool diag, tree arg)
{
if (!fn || fn == error_mark_node)
@ -996,12 +996,6 @@ process_subob_fn (tree fn, bool move_p, tree *spec_p, bool *trivial_p,
}
}
/* Core 1402: A non-trivial non-move ctor suppresses the implicit
declaration of the move ctor/op=. */
if (no_implicit_p && move_p && !move_signature_fn_p (fn)
&& !trivial_fn_p (fn))
*no_implicit_p = true;
if (constexpr_p && !DECL_DECLARED_CONSTEXPR_P (fn))
{
*constexpr_p = false;
@ -1027,7 +1021,7 @@ static void
walk_field_subobs (tree fields, tree fnname, special_function_kind sfk,
int quals, bool copy_arg_p, bool move_p,
bool assign_p, tree *spec_p, bool *trivial_p,
bool *deleted_p, bool *constexpr_p, bool *no_implicit_p,
bool *deleted_p, bool *constexpr_p,
bool diag, int flags, tsubst_flags_t complain)
{
tree field;
@ -1126,7 +1120,7 @@ walk_field_subobs (tree fields, tree fnname, special_function_kind sfk,
{
walk_field_subobs (TYPE_FIELDS (mem_type), fnname, sfk, quals,
copy_arg_p, move_p, assign_p, spec_p, trivial_p,
deleted_p, constexpr_p, no_implicit_p,
deleted_p, constexpr_p,
diag, flags, complain);
continue;
}
@ -1143,8 +1137,8 @@ walk_field_subobs (tree fields, tree fnname, special_function_kind sfk,
rval = locate_fn_flags (mem_type, fnname, argtype, flags, complain);
process_subob_fn (rval, move_p, spec_p, trivial_p, deleted_p,
constexpr_p, no_implicit_p, diag, field);
process_subob_fn (rval, spec_p, trivial_p, deleted_p,
constexpr_p, diag, field);
}
}
@ -1158,7 +1152,7 @@ walk_field_subobs (tree fields, tree fnname, special_function_kind sfk,
static void
synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
tree *spec_p, bool *trivial_p, bool *deleted_p,
bool *constexpr_p, bool *no_implicit_p, bool diag,
bool *constexpr_p, bool diag,
tree inherited_base, tree inherited_parms)
{
tree binfo, base_binfo, scope, fnname, rval, argtype;
@ -1171,9 +1165,6 @@ synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
if (spec_p)
*spec_p = (cxx_dialect >= cxx0x ? noexcept_true_spec : empty_except_spec);
if (no_implicit_p)
*no_implicit_p = false;
if (deleted_p)
{
/* "The closure type associated with a lambda-expression has a deleted
@ -1314,8 +1305,8 @@ synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
if (inherited_base)
argtype = NULL_TREE;
process_subob_fn (rval, move_p, spec_p, trivial_p, deleted_p,
constexpr_p, no_implicit_p, diag, basetype);
process_subob_fn (rval, spec_p, trivial_p, deleted_p,
constexpr_p, diag, basetype);
if (ctor_p && TYPE_HAS_NONTRIVIAL_DESTRUCTOR (basetype))
{
/* In a constructor we also need to check the subobject
@ -1327,8 +1318,8 @@ synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
do they affect constexpr-ness (a constant expression doesn't
throw) or exception-specification (a throw from one of the
dtors would be a double-fault). */
process_subob_fn (rval, false, NULL, NULL,
deleted_p, NULL, NULL, false,
process_subob_fn (rval, NULL, NULL,
deleted_p, NULL, false,
basetype);
}
@ -1342,31 +1333,20 @@ synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
*deleted_p = true;
check_vdtor = false;
}
if (diag && assign_p && move_p
&& BINFO_VIRTUAL_P (base_binfo)
&& rval && TREE_CODE (rval) == FUNCTION_DECL
&& move_fn_p (rval) && !trivial_fn_p (rval))
warning (OPT_Wvirtual_move_assign,
"defaulted move assignment for %qT calls a non-trivial "
"move assignment operator for virtual base %qT",
ctype, basetype);
}
vbases = CLASSTYPE_VBASECLASSES (ctype);
if (vbases == NULL)
/* No virtual bases to worry about. */;
else if (assign_p && move_p && no_implicit_p)
{
/* Don't implicitly declare a defaulted move assignment if a virtual
base has non-trivial move assignment, since moving the same base
more than once is dangerous. */
/* Should the spec be changed to allow vbases that only occur once? */
FOR_EACH_VEC_ELT (tree, vbases, i, base_binfo)
{
tree basetype = BINFO_TYPE (base_binfo);
if (copy_arg_p)
argtype = build_stub_type (basetype, quals, move_p);
rval = locate_fn_flags (base_binfo, fnname, argtype, flags, complain);
if (rval && rval != error_mark_node
&& move_fn_p (rval) && !trivial_fn_p (rval))
{
*no_implicit_p = true;
break;
}
}
}
else if (!assign_p)
{
if (constexpr_p)
@ -1378,14 +1358,14 @@ synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
argtype = build_stub_type (basetype, quals, move_p);
rval = locate_fn_flags (base_binfo, fnname, argtype, flags, complain);
process_subob_fn (rval, move_p, spec_p, trivial_p, deleted_p,
constexpr_p, no_implicit_p, diag, basetype);
process_subob_fn (rval, spec_p, trivial_p, deleted_p,
constexpr_p, diag, basetype);
if (ctor_p && TYPE_HAS_NONTRIVIAL_DESTRUCTOR (basetype))
{
rval = locate_fn_flags (base_binfo, complete_dtor_identifier,
NULL_TREE, flags, complain);
process_subob_fn (rval, false, NULL, NULL,
deleted_p, NULL, NULL, false,
process_subob_fn (rval, NULL, NULL,
deleted_p, NULL, false,
basetype);
}
}
@ -1394,14 +1374,14 @@ synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
/* Now handle the non-static data members. */
walk_field_subobs (TYPE_FIELDS (ctype), fnname, sfk, quals,
copy_arg_p, move_p, assign_p, spec_p, trivial_p,
deleted_p, constexpr_p, no_implicit_p,
deleted_p, constexpr_p,
diag, flags, complain);
if (ctor_p)
walk_field_subobs (TYPE_FIELDS (ctype), complete_dtor_identifier,
sfk_destructor, TYPE_UNQUALIFIED, false,
false, false, NULL, NULL,
deleted_p, NULL,
NULL, false, flags, complain);
false, flags, complain);
pop_scope (scope);
@ -1473,7 +1453,7 @@ maybe_explain_implicit_delete (tree decl)
"definition would be ill-formed:", decl);
pop_scope (scope);
synthesized_method_walk (ctype, sfk, const_p,
NULL, NULL, NULL, NULL, NULL, true,
NULL, NULL, NULL, NULL, true,
DECL_INHERITED_CTOR_BASE (decl), parms);
}
@ -1494,7 +1474,7 @@ explain_implicit_non_constexpr (tree decl)
bool dummy;
synthesized_method_walk (DECL_CLASS_CONTEXT (decl),
special_function_p (decl), const_p,
NULL, NULL, NULL, &dummy, NULL, true,
NULL, NULL, NULL, &dummy, true,
NULL_TREE, NULL_TREE);
}
@ -1507,10 +1487,10 @@ deduce_inheriting_ctor (tree decl)
{
gcc_assert (DECL_INHERITED_CTOR_BASE (decl));
tree spec;
bool trivial, constexpr_, deleted, no_implicit;
bool trivial, constexpr_, deleted;
synthesized_method_walk (DECL_CONTEXT (decl), sfk_inheriting_constructor,
false, &spec, &trivial, &deleted, &constexpr_,
&no_implicit, /*diag*/false,
/*diag*/false,
DECL_INHERITED_CTOR_BASE (decl),
FUNCTION_FIRST_USER_PARMTYPE (decl));
DECL_DELETED_FN (decl) = deleted;
@ -1540,7 +1520,6 @@ implicitly_declare_fn (special_function_kind kind, tree type,
bool deleted_p;
bool trivial_p;
bool constexpr_p;
bool no_implicit_p;
/* Because we create declarations for implicitly declared functions
lazily, we may be creating the declaration for a member of TYPE
@ -1627,11 +1606,10 @@ implicitly_declare_fn (special_function_kind kind, tree type,
deleted_p = DECL_DELETED_FN (DECL_TEMPLATE_RESULT (inherited_ctor));
constexpr_p
= DECL_DECLARED_CONSTEXPR_P (DECL_TEMPLATE_RESULT (inherited_ctor));
no_implicit_p = false;
}
else
synthesized_method_walk (type, kind, const_p, &raises, &trivial_p,
&deleted_p, &constexpr_p, &no_implicit_p, false,
&deleted_p, &constexpr_p, false,
inherited_base, inherited_parms);
/* Don't bother marking a deleted constructor as constexpr. */
if (deleted_p)
@ -1719,7 +1697,6 @@ implicitly_declare_fn (special_function_kind kind, tree type,
DECL_DELETED_FN (fn) = deleted_p;
DECL_DECLARED_CONSTEXPR_P (fn) = constexpr_p;
}
FNDECL_SUPPRESS_IMPLICIT_DECL (fn) = no_implicit_p;
DECL_EXTERNAL (fn) = true;
DECL_NOT_REALLY_EXTERN (fn) = 1;
DECL_DECLARED_INLINE_P (fn) = 1;
@ -1731,6 +1708,18 @@ implicitly_declare_fn (special_function_kind kind, tree type,
if (inherited_ctor && TREE_CODE (inherited_ctor) == TEMPLATE_DECL)
fn = add_inherited_template_parms (fn, inherited_ctor);
/* Warn about calling a non-trivial move assignment in a virtual base. */
if (kind == sfk_move_assignment && !deleted_p && !trivial_p
&& CLASSTYPE_VBASECLASSES (type))
{
location_t loc = input_location;
input_location = DECL_SOURCE_LOCATION (fn);
synthesized_method_walk (type, kind, const_p,
NULL, NULL, NULL, NULL, true,
NULL_TREE, NULL_TREE);
input_location = loc;
}
return fn;
}
@ -1909,17 +1898,6 @@ lazily_declare_fn (special_function_kind sfk, tree type)
|| type_has_user_declared_move_assign (type)))
DECL_DELETED_FN (fn) = true;
/* For move variants, rather than declare them as deleted we just
don't declare them at all. */
if (DECL_DELETED_FN (fn)
&& (sfk == sfk_move_constructor
|| sfk == sfk_move_assignment))
return NULL_TREE;
/* We also suppress implicit move if it would call a non-trivial copy. */
if (FNDECL_SUPPRESS_IMPLICIT_DECL (fn))
return NULL_TREE;
/* A destructor may be virtual. */
if (sfk == sfk_destructor
|| sfk == sfk_move_assignment

10
gcc/doc/invoke.texi
View File

@ -4722,6 +4722,16 @@ using scalars of wider type, which normally is more performance efficient;
and @code{as a single scalar}, which means that vector fits into a
scalar type.
@item -Wno-virtual-move-assign
@opindex Wvirtual-move-assign
@opindex Wno-virtual-move-assign
Suppress warnings about inheriting from a virtual base with a
non-trivial C++11 move assignment operator. This is dangerous because
if the virtual base is reachable along more than one path, it will be
moved multiple times, which can mean both objects end up in the
moved-from state. If the move assignment operator is written to avoid
moving from a moved-from object, this warning can be disabled.
@item -Wvla
@opindex Wvla
@opindex Wno-vla

10
gcc/testsuite/g++.dg/cpp0x/defaulted37.C
View File

@ -3,13 +3,11 @@
struct A
{
int moved = 0;
A& operator=(A&&) { ++moved; }
~A() { if (moved > 1) __builtin_abort(); }
A& operator=(A&&);
};
struct B: virtual A { B& operator=(B&&) = default; };
struct C: virtual A { }; // { dg-error "operator=.const A&" }
struct B: virtual A { B& operator=(B&&) = default; }; // { dg-warning "virtual base" }
struct C: virtual A { }; // { dg-warning "virtual base" }
int main()
{
@ -17,5 +15,5 @@ int main()
b2 = static_cast<B&&>(b1);
C c1, c2;
c2 = static_cast<C&&>(c1); // { dg-error "operator=.const C&" }
c2 = static_cast<C&&>(c1);
}

23
gcc/testsuite/g++.dg/cpp0x/defaulted39.C Normal file
View File

@ -0,0 +1,23 @@
// DR 1402
// { dg-options -std=c++11 }
template <class T> T&& move(T& t);
struct A
{
A(const A&);
};
struct B
{
B(B&&);
};
struct C
{
A a;
B b;
};
extern C c1;
C c2(move(c1));

23
gcc/testsuite/g++.dg/cpp0x/defaulted40.C Normal file
View File

@ -0,0 +1,23 @@
// DR 1402
// { dg-options -std=c++11 }
template <class T> T&& move(T& t);
struct A
{
A(const A&);
};
struct B
{
B(B&&) = delete; // { dg-prune-output "declared" }
};
struct C // { dg-error "deleted" }
{
A a;
B b;
};
extern C c1;
C c2(move(c1)); // { dg-error "deleted" }