[Bug c/110048] undefined reference when build with O0

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110048

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
This is C99 inline semantics - the 'inline' function is only a declaration, not
a definition so you need an additional

void foo (void);

somewhere to create an out-of-line instance.

Or use -fgnu89-inline