[Bug c++/126077] Regression: basic_string::::_M_allocated_capacity' may be used uninitialized

[carel.combrink at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126077

--- Comment #2 from Carel Combrink <carel.combrink at gmail dot com> ---
Fully naming the type fixes the issue and it compiles on gcc 15 and 16 also
```
.id = my_namespace::id_t{...}
```