Anonymous union members initialized with designated initializers does not compile inside template

[liss-h]

The following code fails to compile on at least clang-14,15,16:

struct Inner {
};

struct Outer {
    union {
        Inner inner;
    };
};

template<typename>
void f() {
    Outer x{.inner = {}};
}
        
int main() {
    f<int>();
}

With the following message:

error: field designator (null) does not refer to any field in type 'Outer'
<source>:16:5: note: in instantiation of function template specialization 'f<int>' requested here
    f<int>();
    ^

Removing the template on f resolves the error.

Godbolt: https://godbolt.org/z/Tod1oa1Gd

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[shafik]

Confirmed.