https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118375
--- Comment #3 from Sam James <sjames at gcc dot gnu.org> ---
Ugh, sorry, pasted wrong thing.
It should of course be:
```
a.c: In function ‘main’:
a.c:5:15: error: ‘program_invocation_name’ undeclared (first use in this
function)
5 | char* x = program_invocation_name;
| ^~~~~~~~~~~~~~~~~~~~~~~
a.c:5:15: note: each undeclared identifier is reported only once for each
function it appears in
```
where we should suggest _GNU_SOURCE must be defined (before any includes) to
make the extension available.
