[PATCH 1/2] perf python: Fix probing for some clang command line options

[Arnaldo Carvalho de Melo]

The clang compiler complains about some options even without a source
file being available, while others require one, so use the simple
tools/build/feature/test-hello.c file.

Then check for the "is not supported" string in its output, in addition
to the "unknown argument" already being looked for.

This was noticed when building with clang-13 where -ffat-lto-objects
isn't supported and since we were looking just for "unknown argument"
and not providing a source code to clang, was mistakenly assumed as
being available and not being filtered to set of command line options
provided to clang, leading to a build failure.

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Fangrui Song <maskray@xxxxxxxxxx>
Cc: Florian Fainelli <f.fainelli@xxxxxxxxx>
Cc: Ian Rogers <irogers@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: John Keeping <john@xxxxxxxxxxxx>
Cc: Leo Yan <leo.yan@xxxxxxxxxx>
Cc: Michael Petlan <mpetlan@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Nathan Chancellor <nathan@xxxxxxxxxx>
Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Sedat Dilek <sedat.dilek@xxxxxxxxx>
Link: http://lore.kernel.org/lkml/
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/setup.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
index 483f05004e682081..6156bb87ee3e34cf 100644
--- a/tools/perf/util/setup.py
+++ b/tools/perf/util/setup.py
@@ -1,12 +1,14 @@
-from os import getenv
+from os import getenv, path
 from subprocess import Popen, PIPE
 from re import sub
 
 cc = getenv("CC")
 cc_is_clang = b"clang version" in Popen([cc.split()[0], "-v"], stderr=PIPE).stderr.readline()
+src_feature_tests  = getenv('srctree') + '/tools/build/feature'
 
 def clang_has_option(option):
-    return [o for o in Popen([cc, option], stderr=PIPE).stderr.readlines() if b"unknown argument" in o] == [ ]
+    cc_output = Popen([cc, 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))] == [ ]
 
 if cc_is_clang:
     from distutils.sysconfig import get_config_vars
-- 
2.35.1