linux-kernel - Re: [Linux-6.11-rc4] perf BROKEN with LLVM/Clang 19.1.0-rc3

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Message-ID: <CA+icZUURwYd8nJSdMU7KW6nFjubi-VD2f-a5+zQNQGUxK7+2aw@mail.gmail.com>
Date: Thu, 22 Aug 2024 19:31:55 +0200
From: Sedat Dilek <sedat.dilek@...il.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Namhyung Kim <namhyung@...nel.org>, Ian Rogers <irogers@...gle.com>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Nathan Chancellor <nathan@...nel.org>
Subject: Re: [Linux-6.11-rc4] perf BROKEN with LLVM/Clang 19.1.0-rc3

On Thu, Aug 22, 2024 at 7:19 PM Arnaldo Carvalho de Melo
<acme@...nel.org> wrote:
>
> On Thu, Aug 22, 2024 at 02:12:46PM -0300, Arnaldo Carvalho de Melo wrote:
> > On Thu, Aug 22, 2024 at 07:02:52PM +0200, Sedat Dilek wrote:
> > > On Thu, Aug 22, 2024 at 5:10 PM Arnaldo Carvalho de Melo <acme@...nel.org> wrote:
> > > > +++ b/tools/perf/util/setup.py
> > > > @@ -17,7 +17,7 @@ src_feature_tests  = getenv('srctree') + '/tools/build/feature'
> >
> > > >  def clang_has_option(option):
> > > >      cc_output = Popen([cc, cc_options + option, path.join(src_feature_tests, "test-hello.c") ], stderr=PIPE).stderr.readlines()
> > > > -    return [o for o in cc_output if ((b"unknown argument" in o) or (b"is not supported" in o))] == [ ]
> > > > +    return [o for o in cc_output if ((b"unknown argument" in o) or (b"is not supported" in o) or (b"unknown warning option" in o))] == [ ]
> > > >  if cc_is_clang:
> > > >      from sysconfig import get_config_vars
> > > > @@ -63,6 +63,8 @@ cflags = getenv('CFLAGS', '').split()
> > > >  cflags += ['-fno-strict-aliasing', '-Wno-write-strings', '-Wno-unused-parameter', '-Wno-redundant-decls' ]
> > > >  if cc_is_clang:
> > > >      cflags += ["-Wno-unused-command-line-argument" ]
> > > > +    if clang_has_option("-Wno-cast-function-type-mismatch"):
> > > > +        cflags += ["-Wno-cast-function-type-mismatch" ]
> > > >  else:
> > > >      cflags += ['-Wno-cast-function-type' ]
> >
> > > I tried with your diff with SLIM LLVM toolchains 18 and 19.
> >
> > > Both work - see attached build-logs.
> >
> > > Yes, are right that LLVM/Clang v19 was first introducing:
> >
> > > -Wcast-function-type-mismatch / -Wno-cast-function-type-mismatch
> >
> > > [4] says for LLVM 18.1.8:
> >
> > > -Wcast-function-type
> > > -Wcast-function-type-strict
> >
> > > Feel free to add my Reported-by/Tested-by credentials if you sent a full patch.
> >
> > Thanks for the report and test of the fix, I'll add both tags,
>
> So below is the part that deals with disabling the warning if present,
> the other patch supporting checking warning options I merged as a prep
> patch.
>
> Thanks!
>
> - Arnaldo
>
> From 155212c965b5b23a90b8558449dbfd1c60dad934 Mon Sep 17 00:00:00 2001
> From: Arnaldo Carvalho de Melo <acme@...hat.com>
> Date: Thu, 22 Aug 2024 14:13:49 -0300
> Subject: [PATCH 1/1] perf python: Disable -Wno-cast-function-type-mismatch if
>  present on clang
>
> The -Wcast-function-type-mismatch option was introduced in clang 19 and
> its enabled by default, since we use -Werror, and python bindings do
> casts that are valid but trips this warning, disable it if present.
>
> Reported-by: Sedat Dilek <sedat.dilek@...il.com>
> Tested-by: Sedat Dilek <sedat.dilek@...il.com>
> Cc: Ian Rogers <irogers@...gle.com>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Nathan Chancellor <nathan@...nel.org>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Link: https://lore.kernel.org/lkml/CA+icZUVtHn8X1Tb_Y__c-WswsO0K8U9uy3r2MzKXwTA5THtL7w@mail.gmail.com
> Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> ---
>  tools/perf/util/setup.py | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
> index 26c0f2614fe92eb6..649550e9b7aa8c8f 100644
> --- a/tools/perf/util/setup.py
> +++ b/tools/perf/util/setup.py
> @@ -63,6 +63,8 @@ cflags = getenv('CFLAGS', '').split()
>  cflags += ['-fno-strict-aliasing', '-Wno-write-strings', '-Wno-unused-parameter', '-Wno-redundant-decls' ]
>  if cc_is_clang:
>      cflags += ["-Wno-unused-command-line-argument" ]
> +    if clang_has_option("-Wno-cast-function-type-mismatch"):
> +        cflags += ["-Wno-cast-function-type-mismatch" ]
>  else:
>      cflags += ['-Wno-cast-function-type' ]
>
> --
> 2.46.0
>

Thanks for the patch, Arnanldo.

@Nathan Chancellor
What was the b4 magic to retrieve a patch included in a ML thread?

I tried:

link="https://lore.kernel.org/all/CA+icZUXoJ6BS3GMhJHV3aZWyb5Cz2haFneX0C5pUMUUhG-UVKQ@mail.gmail.com/"

b4 am $link
Grabbing thread from
lore.kernel.org/all/CA%2BicZUXoJ6BS3GMhJHV3aZWyb5Cz2haFneX0C5pUMUUhG-UVKQ@...l.gmail.com/t.mbox.gz
Analyzing 9 messages in the thread
No patches found.

-Sedat-