https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65760
Bug ID: 65760
Summary: invalid use of incomplete type with
std::is_convertible<C, C>
Product: gcc
Version: 4.9.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: etienne at atnnn dot com
The following code fails to compile with GCC 4.9.2 on Linux and OS X:
g++-4.9 -std=c++11 test.cc
I was not able to reduce the code any further:
* Commenting out 4, 5, 6, 7 or 11 causes the code to compile.
* Changing 'C c = C()' to 'C c' or 'C c; c = C()' also causes the code to
compile.
Code:
#include <functional>
struct C {
C() = default;
C(std::function<C(int)>);
C(std::function<C(int, int)>);
template <class T> C operator () (T&&);
template <class T> C operator () (T&&, T&&);
};
int main() {
C c = C();
}
Error output:
In file included from /opt/gcc-4.9.2/include/c++/4.9.2/bits/move.h:57:0,
from /opt/gcc-4.9.2/include/c++/4.9.2/bits/stl_pair.h:59,
from /opt/gcc-4.9.2/include/c++/4.9.2/utility:70,
from /opt/gcc-4.9.2/include/c++/4.9.2/tuple:38,
from /opt/gcc-4.9.2/include/c++/4.9.2/functional:55,
from test-gcc.cc:1:
/opt/gcc-4.9.2/include/c++/4.9.2/type_traits: In instantiation of ‘struct
std::__and_<std::__not_<std::is_same<C, std::function<C(int, int)> > >,
std::__or_<std::is_void<C>, std::is_convertible<C, C> > >’:
/opt/gcc-4.9.2/include/c++/4.9.2/functional:2163:63: required by substitution
of ‘template<class _Res, class ... _ArgTypes> template<class _Cond, class _Tp>
using _Requires = typename std::enable_if<_Cond:: value, _Tp>::type [with _Cond
= std::__and_<std::__not_<std::is_same<C, std::function<C(int, int)> > >,
std::__or_<std::is_void<C>, std::is_convertible<C, C> > >; _Tp = void; _Res =
C; _ArgTypes = {int, int}]’
/opt/gcc-4.9.2/include/c++/4.9.2/functional:2225:9: required by substitution
of ‘template<class _Functor, class> std::function<_Res(_ArgTypes
...)>::function(_Functor) [with _Functor = C; <template-parameter-1-2> =
<missing>]’
/opt/gcc-4.9.2/include/c++/4.9.2/type_traits:1401:39: required by
substitution of ‘template<class _From1, class _To1, class> static
std::true_type std::__is_convertible_helper<_From, _To, false>::__test(int)
[with _From1 = C; _To1 = C; <template-parameter-1-3> = <missing>]’
/opt/gcc-4.9.2/include/c++/4.9.2/type_traits:1410:30: required from ‘struct
std::__is_convertible_helper<C, C, false>’
/opt/gcc-4.9.2/include/c++/4.9.2/type_traits:1416:12: required from ‘struct
std::is_convertible<C, C>’
/opt/gcc-4.9.2/include/c++/4.9.2/type_traits:111:12: required from ‘struct
std::__or_<std::is_void<C>, std::is_convertible<C, C> >’
/opt/gcc-4.9.2/include/c++/4.9.2/type_traits:134:12: required from ‘struct
std::__and_<std::__not_<std::is_same<C, std::function<C(int)> > >,
std::__or_<std::is_void<C>, std::is_convertible<C, C> > >’
/opt/gcc-4.9.2/include/c++/4.9.2/functional:2163:63: required by substitution
of ‘template<class _Res, class ... _ArgTypes> template<class _Cond, class _Tp>
using _Requires = typename std::enable_if<_Cond:: value, _Tp>::type [with _Cond
= std::__and_<std::__not_<std::is_same<C, std::function<C(int)> > >,
std::__or_<std::is_void<C>, std::is_convertible<C, C> > >; _Tp = void; _Res =
C; _ArgTypes = {int}]’
/opt/gcc-4.9.2/include/c++/4.9.2/functional:2225:9: required by substitution
of ‘template<class _Functor, class> std::function<_Res(_ArgTypes
...)>::function(_Functor) [with _Functor = C; <template-parameter-1-2> =
<missing>]’
test-gcc.cc:14:13: required from here
/opt/gcc-4.9.2/include/c++/4.9.2/type_traits:134:12: error: invalid use of
incomplete type ‘std::conditional<true, std::__or_<std::is_void<C>,
std::is_convertible<C, C> >, std::__not_<std::is_same<C, std::function<C(int,
int)> > > >::type {aka struct std::__or_<std::is_void<C>,
std::is_convertible<C, C> >}’
struct __and_<_B1, _B2>
^
/opt/gcc-4.9.2/include/c++/4.9.2/type_traits:111:12: error: declaration of
‘std::conditional<true, std::__or_<std::is_void<C>, std::is_convertible<C, C>
>, std::__not_<std::is_same<C, std::function<C(int, int)> > > >::type {aka
struct std::__or_<std::is_void<C>, std::is_convertible<C, C> >}’
struct __or_<_B1, _B2>
