The -Wp,M options behaviour change

[Jiri Olsa]

On Tue, Nov 29, 2016 at 02:31:36PM +0100, Jiri Olsa wrote:
> hi,
> we noticed behaviour change in Fedora 25 gcc wrt -Wp option.
> 
> We use following command line to generate the dependency file:
>   gcc -Wp,-MD,krava,-MT,krava -c -o ex.o ex.c
> 
> and we get 'krava' file with:
>   krava: ex.c /usr/include/stdc-predef.h /usr/include/stdio.h \
> 
> But when we split -Wp option into 2 -Wp options like:
>   gcc -Wp,-MD,krava -Wp,MT,krava -c -o ex.o ex.c
> 
> we get:
>   ex.o krava: ex.c /usr/include/stdc-predef.h /usr/include/stdio.h \
> 
> notice the extra 'ex.o' target.
> 
> We see this behaviour in Fedora 25. It's ok in Fedora 24, which seems odd
> because both have same gcc version 6.2.1. Please check full output below.

more info on this.. it's not fedora version related, it's related
to having ccache installed (kudos to Arnaldo ;-) )

with ccache installed above behaviour happens in both Fedora 24 and 25

thanks,
jirka