Re: [kbuild-all] Re: [PATCH] compiler_attributes.h: Support no_sanitize_undefined check with GCC 4

[Rong Chen <rong.a.chen@intel.com>]

On Tue, Jun 16, 2020 at 03:19:21PM +0200, Peter Zijlstra wrote:
> On Tue, Jun 16, 2020 at 01:15:29AM +0200, Marco Elver wrote:
> > UBSAN is supported since GCC 4.9, which unfortunately did not yet have
> > __has_attribute(). To work around, the __GCC4_has_attribute workaround
> > requires defining which compiler version supports the given attribute.
> > 
> > In the case of no_sanitize_undefined, it is the first version that
> > supports UBSAN, which is GCC 4.9.
> > 
> > Reported-by: kernel test robot <lkp@intel.com>
> > Signed-off-by: Marco Elver <elver@google.com>
> > ---
> > 
> > Doing a 'make W=1' with GCC 4.9 and the provided config fixes the build
> > robot's report.
> > 
> > Peter: Feel free to either squash this patch into the one adding
> > __no_sanitize_undefined or apply on top.
> 
> Yeah, argh! So I only saw this thread now, even though I'd already
> pushed out x86/entry to tip last night due to getting:
> 
> 301805 N + Jun 16 kernel test rob (5.8K) [peterz-queue:x86/entry] BUILD SUCCESS 8e8bb06d199a5aa7a534aa3b3fc0abbbc11ca438
> 
> Why that thing is claiming SUCCESS when it introduces a build error I
> don't know.
> 


Hi Peter,

Sorry for the misunderstanding, some folks complained that it's too
noisy when there're only new warnings in a "BUILD REGRESSION" report,
so we changed to use "BUILD SUCCESS" if there's no new build error. To
avoid misunderstanding, we'll change build complete report title to
"BUILD SUCCESS WITH WARNING" for new warnings.

Best Regards,
Rong Chen