On 02/04/17 02:45 +0300, Ville Voutilainen wrote:
PR libstdc++/79141
* include/bits/stl_pair.h (__wrap_nonesuch): New.
(operator=(typename conditional<
__and_<is_copy_assignable<_T1>,
is_copy_assignable<_T2>>::value,
const pair&, const __wrap_nonesuch&>::type)): Change __nonesuch
to __wrap_nonesuch.
(operator=(typename conditional<
__not_<__and_<is_copy_assignable<_T1>,
is_copy_assignable<_T2>>>::value,
const pair&, const __nonesuch&>::type)): Likewise.
(operator=(typename conditional<
__and_<is_move_assignable<_T1>,
is_move_assignable<_T2>>::value,
pair&&, __wrap_nonesuch&&>::type)): Likewise.
* testsuite/20_util/pair/79141.cc: New.
diff --git a/libstdc++-v3/include/bits/stl_pair.h
b/libstdc++-v3/include/bits/stl_pair.h
index 7c7cee2..b746fb4 100644
--- a/libstdc++-v3/include/bits/stl_pair.h
+++ b/libstdc++-v3/include/bits/stl_pair.h
@@ -179,6 +179,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
};
+ struct __wrap_nonesuch : std::__nonesuch {
+ explicit __wrap_nonesuch(const __nonesuch&) = delete;
+ };
Could you please add a comment explaining that this is needed to
ensure that functions with parameters of this type are not viable when
an argument of {} is used. Because even with such a comment I'll
probably not understand this by next week.
And I think __explicit_nonesuch or __no_list_init would be a clearer
name. We're not really "wrapping" this, unless I misunderstand.
OK for trunk, I suppose.
This kind of thing is why I want to burn std::pair and std::tuple to
the ground.
