Given the following source (from issue 63999):

struct Type {
    enum { Unused };
    int value = 0;
};
int main() {
    Type t;
    return t.value;
}

The enumeration type isn't used anywhere, so by default the DWARF doesn't contain a description of the unused enum, which is fine.

Normally, an unused type can be emitted by adding -fno-eliminate-unused-debug-types however that seems not to apply to unused enums. It should.