ambiguous overload for TORCH_LIBRARY def

[ngc92]

🐛 Describe the bug

The two overloads of library.def,

template <typename Schema>
Library& def(
      Schema&& raw_schema,
      const std::vector<at::Tag>& tags = {},
      _RegisterOrVerify rv = _RegisterOrVerify::REGISTER) & {
    c10::FunctionSchema s = schema(std::forward<Schema>(raw_schema));
    return _def(std::move(s), nullptr, tags, rv);
}
  
template <typename NameOrSchema, typename Func>
Library& def(NameOrSchema&& raw_name_or_schema, Func&& raw_f,
      const std::vector<at::Tag>& tags = {}) & {
    CppFunction f(std::forward<Func>(raw_f));
    return _def(
        detail::constructSchemaOrName(
            ::std::forward<NameOrSchema>(raw_name_or_schema)),
        ::std::move(f), tags);
}

are ambiguous when tags are used: Func&& matches anything, so both options appear as viable overloads.

The second overload should be SFINAEd away if Func is a vector of tags.

Versions

PyTorch version: 2.3.0+cu121

cc @ezyang @bhosmer @smessmer @ljk53 @bdhirsh

[ezyang]

Whoops. Do you think you could send us a patch?