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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/96355] [10/11 Regression] [concepts] internal compiler
 error: in tsubst_pack_expansion, at cp/pt.c:12928
Date: Thu, 27 Aug 2020 12:47:47 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D96355

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Robert Douglas from comment #1)
> I've also hit this issue in upgrading from 9.1 to 10.2
>=20
> I presume it run into the same issue, but if it helps, this more closely
> matches my use case:
> https://godbolt.org/z/zb1bP5

That code:

template<typename... Params>
concept ParamsRemain =3D requires(Params)
{ requires sizeof...(Params) > 0; };

template<typename... Params>
void foo()
{
        static constexpr bool pr1 =3D ParamsRemain<Params...>;
};

int main()
{
        foo<>();
        return 0;
}

compiles with GCC 9 and -std=3Dc++2a -fconcepts

compiles with GCC 10.1 and -std=3Dc++2a

ice-on-valid-code with GCC 10.2.0, 10.2.1 and 11.0 with -std=3Dc++2a=