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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/114393] [14 regression] over eager "invalid use of void
 expression" ? since r14-2170-g4cf64d9cc2faf4
Date: Wed, 20 Mar 2024 04:04:37 +0000
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X-Bugzilla-Keywords: c++-lambda, rejects-valid
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114393

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reduced testcase which shows this never worked:
```
template <auto _DescriptorFn> struct c1 {};

template <class _Descriptor, auto t =3D [] { return _Descriptor();}>
inline constexpr auto b_v =3D t;

template <class _Tag>
using c1_t =3D c1<b_v<int>>;

template <class _Data>
constexpr auto g(_Data __data) {
    return c1_t<_Data>{};
}

void f() {
  auto &&b =3D g(0);
}
```

I don't know understand how the original testcase worked in GCC 13 when the
above testcase never worked ...=