https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65706
Andreas Herrmann <andreash87 at gmx dot ch> changed:
What |Removed |Added
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CC| |andreash87 at gmx dot ch
--- Comment #2 from Andreas Herrmann <andreash87 at gmx dot ch> ---
I just stumbled up this problem in GCC 5.2.0. And it seems that Bug 66336 is a
duplicate of this one.
$ g++ --version
g++ (GCC) 5.2.0
Copyright (C) 2015 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.
$ cat bug.cc
template <class T, T value_>
struct constant {
using type = T;
static constexpr T value = value_;
};
template <class Constant>
constexpr typename Constant::type get = Constant::value;
template <class... Args>
void callme(Args...) {}
template <class... Args>
void works(Args...) {
callme(Args::value...);
}
template <class... Args>
void fails(Args...) {
callme(get<Args>...); // !!! Parameter pack is not expanded.
}
int main() {
int x = get<constant<int, 1>>; // The variable template works on its own.
works(constant<int, 0>{}, constant<int, 1>{});
fails(constant<int, 0>{}, constant<int, 1>{});
}
$ g++ -std=c++14 bug.cc
bug.cc: In function ‘void fails(Args ...)’:
bug.cc:20:21: error: expansion pattern ‘get<Args>’ contains no argument packs
callme(get<Args>...); // !!! Parameter pack is not expanded.
