https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62072
Bug ID: 62072
Summary: [4.9/4.10 regression] No SFINAE performed for function
type
Product: gcc
Version: 4.10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: lucdanton at free dot fr
$ cat main.cpp
template<typename T> struct tuple_size {};
template<typename T> struct tuple_size<T const>: tuple_size<T> {};
template<typename T, typename = void>
struct query {
static constexpr bool value = false;
};
template<typename T>
struct query<T, typename tuple_size<T>::type> {
static constexpr bool value = true;
};
int main()
{
// fine
static_assert( !query<int>::value, "" );
static_assert( !query<int const>::value, "" );
// error: invalid use of incomplete type 'struct tuple_size<void()>'
static_assert( !query<void()>::value, "" );
}
$ g++-trunk --version
g++-trunk (GCC) 4.10.0 20140809 (experimental)
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ g++-trunk -std=c++11 main.cpp
main.cpp: In instantiation of 'struct tuple_size<void()>':
main.cpp:20:34: required from here
main.cpp:2:29: error: invalid use of incomplete type 'struct
tuple_size<void()>'
template<typename T> struct tuple_size<T const>: tuple_size<T> {};
^
main.cpp:2:29: note: declaration of 'struct tuple_size<void()>'
----------
The testcase compiles fine against GCC 4.8.2 and 4.9.0.
