Erroneous overload resolution with multiple direct bases

[K-ballo]

Bugzilla Link	20222
Version	trunk
OS	All
CC	@DougGregor

Extended Description

The following snippet results in a static_assert failure, I believe the overload resolution should be ambiguous instead:

    template <int I>
    struct int_ {};

    template <int I>
    void foo(int_<I>){ static_assert(I != 1, ""); }

    struct bar : int_<0>, int_<1> {};

    int main() {
      foo(bar{});
    }

[Endilll]

Single function template can't produce two overload candidates after deduction, so no ambiguity here. Instead, we fail deduction since Clang 3.9: https://godbolt.org/z/cGve6x6rW

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Agustín Bergé (K-ballo)

| | | | --- | --- | | Bugzilla Link | [20222](https://llvm.org/bz20222) | | Version | trunk | | OS | All | | CC | @DougGregor |

Extended Description

The following snippet results in a static_assert failure, I believe the overload resolution should be ambiguous instead:

    template <int I>
    struct int_ {};

    template <int I>
    void foo(int_<I>){ static_assert(I != 1, ""); }

    struct bar : int_<0>, int_<1> {};

    int main() {
      foo(bar{});
    }