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

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Message-ID: <20251006222116.3335193-1-irogers@google.com>
Date: Mon,  6 Oct 2025 15:21:16 -0700
From: Ian Rogers <irogers@...gle.com>
To: 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>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Nathan Chancellor <nathan@...nel.org>, Nick Desaulniers <nick.desaulniers+lkml@...il.com>, 
	Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>, 
	James Clark <james.clark@...aro.org>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: [PATCH v1] perf build: Don't leave a.out file when building with clang

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>
---
 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