https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63885
Bug ID: 63885
Summary: ICE in static assert of constexpr forwarding xvalue
container member rvalue reference
Product: gcc
Version: 5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: listcrawler at gmail dot com
Created attachment 33983
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33983&action=edit
preprocessed source file
Internal compiler error in static assert of constexpr forwarding xvalue
container member rvalue reference.
g++ 4.8 and 4.9 passes, but trunk built from r217559 on ubuntu 14.04 fails
compilation with
$ g++-trunk -std=c++11 -Wall -Wextra constexpr_static_assert.ii
constexpr_static_assert.cpp:50:39: in constexpr expansion of ‘get<0, S<int&&>
>((* & S<int&&>((* &1))))’
constexpr_static_assert.cpp:35:35: in constexpr expansion of ‘__get<0,
T>::value<S<int&&>&&>((* & std::forward<S<int&&> >((* & arg))))’
constexpr_static_assert.cpp:50:44: internal compiler error: in
verify_ctor_sanity, at cp/constexpr.c:1779
static_assert (get <0> (S <int &&> (1)) == 1, ""); // g++ 4.9 passes, g++
trunk r217559 fails
...
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
//
// source
//
#include <utility>
using namespace std;
///////////////////////////////////////////////////////////////////////////////
template <typename C> struct member_forward
{
typedef typename remove_reference <C>::type::type T;
typedef typename conditional
<
is_lvalue_reference <C &&>::value && not is_reference <T>::value,
typename add_lvalue_reference <T>::type,
T
>::type type;
};
template <typename C> using member_forward_t = typename member_forward
<C>::type;
///////////////////////////////////////////////////////////////////////////////
template <int , typename > struct __get;
template < typename T> struct __get <0, T>
{
constexpr static auto value (T arg)
-> decltype ((forward <member_forward_t <T>> (arg.t)))
{
return forward <member_forward_t <T>> (arg.t);
}
};
template <int N, typename T> constexpr auto get (T && arg)
-> decltype (__get <N, T &&>::value (forward <T> (arg)))
{
return __get <N, T &&>::value (forward <T> (arg));
}
///////////////////////////////////////////////////////////////////////////////
template <typename T> struct S
{
typedef T type;
T t;
template <typename U> constexpr S (U && u) : t (forward <U> (u)) {}
};
///////////////////////////////////////////////////////////////////////////////
static_assert (get <0> (S <int &&> (1)) == 1, ""); // g++ 4.9 passes, g++ trunk
r217559 fails
int main () {}
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
