[Bug libgomp/60670] omp.h may differ between multilibs

[egall at gwmail dot gwu.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60670

Eric Gallager <egall at gwmail dot gwu.edu> changed:

           What    |Removed                     |Added
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                 CC|                            |egall at gwmail dot gwu.edu

--- Comment #9 from Eric Gallager <egall at gwmail dot gwu.edu> ---
(In reply to ro@CeBiTec.Uni-Bielefeld.DE from comment #2)
> > --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
> > Or the header needs to include all variants with proper #ifdef-ery
> 
> This is difficult for a header generated per multilib at build time.
>

GNU diff can can merge two C/C++ header files with the proper ifdef-ery: see:
http://www.gnu.org/software/diffutils/manual/html_mono/diff.html#If-then-else
and also:
http://www.gnu.org/software/diffutils/manual/html_mono/diff.html#Detailed%20If-then-else

This could be done as part of the generation of the header at build time.