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@google.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

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@google.com>

Tested-by: Justin Stitt <justinstitt@google.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

On Mon, Oct 6, 2025 at 3:21 PM Ian Rogers <irogers@google.com> 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@google.com>

Maybe a fixes tag of:
Fixes: 5508672d7f49 perf python: Remove -mcet and -fcf-protection when
building with clang

Thanks,
Ian

> ---
>  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
>