linux-kernel - Re: [PATCH v1 4/6] perf build: Disable fewer flex warnings

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Message-ID: <ZMPKekDl+g5PeiH8@kernel.org>
Date:   Fri, 28 Jul 2023 11:02:34 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     James Clark <james.clark@....com>
Cc:     Ian Rogers <irogers@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Eduard Zingerman <eddyz87@...il.com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Gaosheng Cui <cuigaosheng1@...wei.com>,
        Rob Herring <robh@...nel.org>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        bpf@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH v1 4/6] perf build: Disable fewer flex warnings

Em Fri, Jul 28, 2023 at 10:59:38AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Fri, Jul 28, 2023 at 09:50:59AM +0100, James Clark escreveu:
> > 
> > 
> > On 28/07/2023 07:49, Ian Rogers wrote:
> > > If flex is version 2.6.4, reduce the number of flex C warnings
> > > disabled. Earlier flex versions have all C warnings disabled.
> > 
> > Hi Ian,
> > 
> > I get a build error with either this one or the bison warning change:
> > 
> >   $ make LLVM=1 -C tools/perf NO_BPF_SKEL=1 DEBUG=1
> > 
> >   util/pmu-bison.c:855:9: error: variable 'perf_pmu_nerrs' set but not
> > used [-Werror,-Wunused-but-set-variable]
> >     int yynerrs = 0;
> > 
> > I tried a clean build which normally fixes these kind of bison errors.
> > Let me know if you need any version info.
> 
> Trying to build it with the command line above I get:
> 
>   CC      util/expr.o
>   CC      util/parse-events.o
>   CC      util/parse-events-flex.o
> util/parse-events-flex.c:7503:13: error: misleading indentation; statement is not part of the previous 'if' [-Werror,-Wmisleading-indentation]
>             if ( ! yyg->yy_state_buf )
>             ^
> util/parse-events-flex.c:7501:9: note: previous statement is here
>         if ( ! yyg->yy_state_buf )
>         ^

I added this to the patch to get it moving:

make: Leaving directory '/var/home/acme/git/perf-tools-next/tools/perf'
⬢[acme@...lbox perf-tools-next]$ git diff
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 32239c4b0393c319..afa93eff495811cf 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -281,7 +281,7 @@ $(OUTPUT)util/bpf-filter-bison.c $(OUTPUT)util/bpf-filter-bison.h: util/bpf-filt

 FLEX_GE_264 := $(shell expr $(shell $(FLEX) --version | sed -e  's/flex \([0-9]\+\).\([0-9]\+\).\([0-9]\+\)/\1\2\3/g') \>\= 264)
 ifeq ($(FLEX_GE_264),1)
-  flex_flags := -Wno-redundant-decls -Wno-switch-default -Wno-unused-function
+  flex_flags := -Wno-redundant-decls -Wno-switch-default -Wno-unused-function -Wno-misleading-indentation
 else
   flex_flags := -w
 endif
⬢[acme@...lbox perf-tools-next]$


> 1 error generated.
> make[4]: *** [/var/home/acme/git/perf-tools-next/tools/build/Makefile.build:97: util/parse-events-flex.o] Error 1
> make[4]: *** Waiting for unfinished jobs....
>   LD      util/scripting-engines/perf-in.o
> make[3]: *** [/var/home/acme/git/perf-tools-next/tools/build/Makefile.build:140: util] Error 2
> make[2]: *** [Makefile.perf:682: perf-in.o] Error 2
> make[2]: *** Waiting for unfinished jobs....
>   CC      pmu-events/pmu-events.o
>   LD      pmu-events/pmu-events-in.o
> make[1]: *** [Makefile.perf:242: sub-make] Error 2
> make: *** [Makefile:70: all] Error 2
> 
> ⬢[acme@...lbox perf-tools-next]$ clang --version
> clang version 14.0.5 (Fedora 14.0.5-2.fc36)
> Target: x86_64-redhat-linux-gnu
> Thread model: posix
> InstalledDir: /usr/bin
> ⬢[acme@...lbox perf-tools-next]$

-- 

- Arnaldo