Re: [PATCH 1/1] perf annotate: Initialize 'arch' variable not to trip some -Werror=maybe-uninitialized

[Arnaldo Carvalho de Melo]

On Wed, Apr 03, 2024 at 09:01:56AM -0700, Ian Rogers wrote:
> On Wed, Apr 3, 2024 at 8:16 AM Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
> >
> > In some older distros the build is failing due to
> > -Werror=maybe-uninitialized, in this case we know that this isn't the
> > case because 'arch' gets initialized by evsel__get_arch(), so just init
> > it to NULL to silence those cases.
> >
> > E.g.:
> >
> >     32    17.12 opensuse:15.5                 : FAIL gcc version 7.5.0 (SUSE Linux)
> >         util/annotate.c: In function 'hist_entry__get_data_type':
> >     util/annotate.c:2269:15: error: 'arch' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> >       struct arch *arch;
> >                    ^~~~
> >     cc1: all warnings being treated as errors
> >
> >       43     7.30 ubuntu:18.04-x-powerpc64el    : FAIL gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
> >     util/annotate.c: In function 'hist_entry__get_data_type':
> >     util/annotate.c:2351:36: error: 'arch' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> >        if (map__dso(ms->map)->kernel && arch__is(arch, "x86") &&
> >                                         ^~~~~~~~~~~~~~~~~~~~~
> >     cc1: all warnings being treated as errors
> >
> > Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> > Cc: Ian Rogers <irogers@xxxxxxxxxx>
> > Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> > Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> 
> This looks fine but I couldn't line up the errors with code in the
> tree. I was curious why the "maybe-uninitialized" was failing. Perhaps
> evsel__get_arch should set the out argument to NULL when an error
> occurs. This fix is also good but may potentially need repeating for
> other evsel__get_arch cases, so a fix in evsel__get_arch may be
> preferable.
> 
> Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Trying with this on top, i.e. what you suggests: