[clang] -Wunique-object-duplication in static class member functions, intentional?

[carlosgalvezp]

Hi,

We are getting hits of the -Wunique-object-duplication warning in this type of code:

struct Foo
{
    Foo& get()
    {
        static Foo f{};  // -Wunique-object-duplication
        return f;
    }
};

Example: https://godbolt.org/z/nhEj7rnbh

I did not see this use case in the unit tests, so I wonder if warning here is intentional?

Thanks!

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Carlos Galvez (carlosgalvezp)

Hi,

We are getting hits of the -Wunique-object-duplication warning in this type of code:

struct Foo
{
    Foo& get()
    {
        static Foo f{};  // -Wunique-object-duplication
        return f;
    }
};

Example: https://godbolt.org/z/qnKrEnh1d

I did not see this use case in the unit tests, so I wonder if warning here is intentional?

Thanks!

[shafik]

CC @DKLoehr

[DKLoehr]

Yes, this is a variant of the "Static local in externally-visible function" case. If the function is hidden, there will may multiple copies of f if the header is included in multiple shared libraries.