Re: [jani:device-info-inheritance-v3 3/19] drivers/gpu/drm/i915/i915_pci.c:212:2: error: initializer element is not a compile-time constant

[Philip Li <philip.li@intel.com>]

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On Tue, Mar 10, 2020 at 10:51:29AM +0200, Jani Nikula wrote:
> On Mon, 09 Mar 2020, Nick Desaulniers <ndesaulniers@google.com> wrote:
> > On Mon, Mar 9, 2020 at 1:32 AM Jani Nikula <jani.nikula@linux.intel.com> wrote:
> >>
> >> On Fri, 06 Mar 2020, Nick Desaulniers <ndesaulniers@google.com> wrote:
> >> > Based on the tree, I think this report was meant to go to Jani (cc'ed)?
> >>
> >> It baffles me that the build bot burns resources on building random
> >> branches in my personal repositories.
> >
> > It uses a branch naming convention to avoid testing branches:
> > https://github.com/intel/lkp-tests/wiki/LKP-FAQ#is-there-a-way-not-to-trigger-kbuild-tests-on-a-specific-branch
> >
> > But in this case, it seems it caught a build breakage even further
> > upstream, which is valuable, right?
> 
> I guess, though I usually only use it to share some half-baked
> stuff. Perhaps I'll also start using it for build testing some of the
> more obscure ideas. ;)
> 
> >> That said, this builds on GCC 8 just fine. Is clang not able to do this?
> >
> > Places that require integer constant expressions can be very subtle.
> > See this recent example in i915 for example:
> > https://github.com/ClangBuiltLinux/linux/issues/918
> > Sometimes reproducing also depends on some configs.  In this case,
> > it's not as I've fetched your branch and can repro on defconfig.
> 
> Yeah, reminds me of earlier issues with GCC and Clang having different
> order in certain checks and optimizations, leading to Clang warnings in
> code that GCC just optimized away.
> 
> > This is definitely our bug: https://bugs.llvm.org/show_bug.cgi?id=45157
> 
> Any idea if older GCC is also limited in this regard? What versions does
> the kbuild bot test?
Hi Jani, we have gcc-4.9/gcc-5/gcc-6/gcc-7 now, gcc-7 is default, and others
will be picked up randomly, thus it may not have chance to test this commit
yet, we can give a try to let you know later.

> 
> BR,
> Jani.
> 
> 
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center
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