[Bug c++/80438] Variadic template class argument deduction failure from variadic constructor deduction guide

[ed at catmur dot uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80438

Ed Catmur <ed at catmur dot uk> changed:

           What    |Removed                     |Added
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                 CC|                            |ed at catmur dot uk

--- Comment #2 from Ed Catmur <ed at catmur dot uk> ---
Workaround: add an N=1+ deduction guide:

    // existing
    template <typename... Us>
    foo(Us...) -> foo<Us...>;
    // additional, for g++
    template <typename U, typename... Us>
    foo(U, Us...) -> foo<U, Us...>;