From: David Laight <David.Laight@ACULAB.COM>
To: 'Ian Rogers' <irogers@google.com>,
Nick Desaulniers <nick.desaulniers@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Jin Yao <yao.jin@linux.intel.com>,
Changbin Du <changbin.du@intel.com>,
John Keeping <john@metanate.com>,
Song Liu <songliubraving@fb.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] perf: fix -Wstring-compare
Date: Mon, 24 Feb 2020 16:03:24 +0000 [thread overview]
Message-ID: <dad75d5a7aa443e39dc20972d80ee83c@AcuMS.aculab.com> (raw)
In-Reply-To: <CAP-5=fU=+uYZDb2uSFO8CTJ-Ange4Nxh4mmsOC1MS=Tedois9g@mail.gmail.com>
From: Ian Rogers
> Sent: 24 February 2020 05:56
> On Sun, Feb 23, 2020 at 11:35 AM Nick Desaulniers
> <nick.desaulniers@gmail.com> wrote:
> >
> > Clang warns:
> >
> > util/block-info.c:298:18: error: result of comparison against a string
> > literal is unspecified (use an explicit string comparison function
> > instead) [-Werror,-Wstring-compare]
> > if ((start_line != SRCLINE_UNKNOWN) && (end_line != SRCLINE_UNKNOWN)) {
> > ^ ~~~~~~~~~~~~~~~
> > util/block-info.c:298:51: error: result of comparison against a string
> > literal is unspecified (use an explicit string comparison function
> > instead) [-Werror,-Wstring-compare]
> > if ((start_line != SRCLINE_UNKNOWN) && (end_line != SRCLINE_UNKNOWN)) {
> > ^ ~~~~~~~~~~~~~~~
> > util/block-info.c:298:18: error: result of comparison against a string
> > literal is unspecified (use an explicit string
> > comparison function instead) [-Werror,-Wstring-compare]
> > if ((start_line != SRCLINE_UNKNOWN) && (end_line != SRCLINE_UNKNOWN)) {
> > ^ ~~~~~~~~~~~~~~~
> > util/block-info.c:298:51: error: result of comparison against a string
> > literal is unspecified (use an explicit string comparison function
> > instead) [-Werror,-Wstring-compare]
> > if ((start_line != SRCLINE_UNKNOWN) && (end_line != SRCLINE_UNKNOWN)) {
> > ^ ~~~~~~~~~~~~~~~
> > util/map.c:434:15: error: result of comparison against a string literal
> > is unspecified (use an explicit string comparison function instead)
> > [-Werror,-Wstring-compare]
> > if (srcline != SRCLINE_UNKNOWN)
> > ^ ~~~~~~~~~~~~~~~
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/900
> > Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
> > ---
> > Note: was generated off of mainline; can rebase on -next if it doesn't
> > apply cleanly.
>
> Looks good to me. Some more context:
> https://clang.llvm.org/docs/DiagnosticsReference.html#wstring-compare
> The spec says:
> J.1 Unspecified behavior
> The following are unspecified:
> .. Whether two string literals result in distinct arrays (6.4.5).
Just change the (probable):
#define SRCLINE_UNKNOWN "unknown"
with
static const char SRC_LINE_UNKNOWN[] = "unk";
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-02-24 16:03 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-23 19:34 [PATCH] perf: fix -Wstring-compare Nick Desaulniers
2020-02-24 5:55 ` Ian Rogers
2020-02-24 16:03 ` David Laight [this message]
2020-02-24 18:19 ` Ian Rogers
2020-02-24 22:05 ` Nick Desaulniers
2020-02-25 9:35 ` David Laight
2020-02-25 21:28 ` Nick Desaulniers
2020-03-03 20:06 ` Arnaldo Carvalho de Melo
2020-03-07 7:36 ` [tip: perf/urgent] perf diff: Fix undefined string comparision spotted by clang's -Wstring-compare tip-bot2 for Nick Desaulniers
2020-03-19 14:10 ` [tip: perf/core] perf diff: Fix undefined string comparison " tip-bot2 for Nick Desaulniers
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