[Bug libstdc++/122903] gjs-1.86.0 fails to build since r16-4100-gaaeca77a79a9a8

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122903

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Definitely not a bug, but I'm considering supporting it as an extension, so we
don't break code which used to work (even though it was technically invalid).

But supporting that invalid code is not a high priority.