[Bug objc/117478] -ObjC is not accepted: error: argument to '-O' should be a non-negative integer, 'g', 's', 'z' or 'fast'

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117478

--- Comment #4 from Iain Sandoe <iains at gcc dot gnu.org> ---
-ObjC is not exactly clang-specific - AFAIR it was supported by Apple gcc-4.x
as well,

Perhaps we can support it as a driver flag (which is used as shorthand for -x
objective-c)

I'm short of time at the moment to try this, but will do so at some point (or
I'd be happy to review a patch to do so).