linux-kernel - Re: [PATCH v1] perf build: Don't leave a.out file when building with clang

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Message-ID: <csrtenswfduvfgyalcydxudcwjo7ezt5vuvfxkkrbpza6o3cls@t55uhpt4363z>
Date: Mon, 6 Oct 2025 16:39:45 -0700
From: Justin Stitt <justinstitt@...gle.com>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Adrian Hunter <adrian.hunter@...el.com>, Nathan Chancellor <nathan@...nel.org>, 
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>, Bill Wendling <morbo@...gle.com>, 
	James Clark <james.clark@...aro.org>, linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, 
	llvm@...ts.linux.dev
Subject: Re: [PATCH v1] perf build: Don't leave a.out file when building with
 clang

Hi,

On Mon, Oct 06, 2025 at 03:21:16PM -0700, Ian Rogers wrote:
> Testing clang features doesn't specify a "-o" option so an a.out file
> is created and left in the make directory (not the output). Fix this
> by specifying a "-o" of "/dev/null". Reorganize the code a little to
> help with readability.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>

Tested-by: Justin Stitt <justinstitt@...gle.com>

> ---
>  tools/perf/util/setup.py | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
> index dd289d15acfd..6caf2126b1cd 100644
> --- a/tools/perf/util/setup.py
> +++ b/tools/perf/util/setup.py
> @@ -22,8 +22,16 @@ assert srctree, "Environment variable srctree, for the Linux sources, not set"
>  src_feature_tests  = f'{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) or (b"unknown warning option" in o))] == [ ]
> +    error_substrings = (
> +        b"unknown argument",
> +        b"is not supported",
> +        b"unknown warning option"
> +    )
> +    clang_command = [cc, cc_options + option,
> +                     "-o", "/dev/null",
> +                     path.join(src_feature_tests, "test-hello.c") ]
> +    cc_output = Popen(clang_command, stderr=PIPE).stderr.readlines()
> +    return not any(any(error in line for error in error_substrings) for line in cc_output)
>  
>  if cc_is_clang:
>      from sysconfig import get_config_vars
> -- 
> 2.51.0.618.g983fd99d29-goog
> 
>

Thanks
Justin