You are right that changing this behavior would have serious consequences.
But wouldn't you agree that gcc could somehow distinguish whether the input
files is of *.c or *.s source kind, and then decide if it should pass -I to
the assembler or the preprocessor or  both? That would be more in line with
what I would expect after reading the documentation. Passing -I to the
assembler when invoking the command 'gcc -c source.c' seems unnecessary. Of
course I admit there could be something I'm missing here.

sob., 24 wrz 2022 o 07:13 Xi Ruoyao <xry111@xry111.site> napisał(a):

> On Fri, 2022-09-23 at 23:11 +0200, mizo 91 wrote:
> > > From GNU assembler manual:
> > >
> > >     -I dir
> > >       Add directory dir to the search list for ".include"
> > > directives.
> > >
> > > So -I flags may be for preprocessor, or for assembler.
> >
> > I'm not calling the assembler. Im calling gcc. Check what gcc manual
> > have to say about it.
>
> The problem is it's common to use "gcc -c foo.s" instead of "as foo.s -o
> foo.o" in the building system of the packages.  It can ensure the
> assembler used for both C files and assembly files the same one.  If you
> suddenly stop to pass -I options to the assembler, you can break the
> building process of existing packages.
> --
> Xi Ruoyao <xry111@xry111.site>
> School of Aerospace Science and Technology, Xidian University
>