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From: tip-bot for Jiri Olsa <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: mingo@kernel.org, tglx@linutronix.de,
	alexander.shishkin@linux.intel.com, linux-kernel@vger.kernel.org,
	sergey.senozhatsky.work@gmail.com, hpa@zytor.com,
	acme@redhat.com, dsahern@gmail.com, jolsa@kernel.org,
	namhyung@kernel.org, jpoimboe@redhat.com, peterz@infradead.org
Subject: [tip:perf/core] perf tools: Fix python extension build for gcc 8
Date: Mon, 19 Mar 2018 23:34:54 -0700	[thread overview]
Message-ID: <tip-b7a313d84e853049062011d78cb04b6decd12f5c@git.kernel.org> (raw)
In-Reply-To: <20180319082902.4518-2-jolsa@kernel.org>

Commit-ID:  b7a313d84e853049062011d78cb04b6decd12f5c
Gitweb:     https://git.kernel.org/tip/b7a313d84e853049062011d78cb04b6decd12f5c
Author:     Jiri Olsa <jolsa@kernel.org>
AuthorDate: Mon, 19 Mar 2018 09:29:02 +0100
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 19 Mar 2018 13:39:46 -0300

perf tools: Fix python extension build for gcc 8

The gcc 8 compiler won't compile the python extension code with the
following errors (one example):

  python.c:830:15: error: cast between incompatible  function types from              \
  ‘PyObject * (*)(struct pyrf_evsel *, PyObject *, PyObject *)’                       \
  uct _object * (*)(struct pyrf_evsel *, struct _object *, struct _object *)’} to     \
  ‘PyObject * (*)(PyObject *, PyObject *)’ {aka ‘struct _object * (*)(struct _objeuct \
  _object *)’} [-Werror=cast-function-type]
     .ml_meth  = (PyCFunction)pyrf_evsel__open,

The problem with the PyMethodDef::ml_meth callback is that its type is
determined based on the PyMethodDef::ml_flags value, which we set as
METH_VARARGS | METH_KEYWORDS.

That indicates that the callback is expecting an extra PyObject* arg, and is
actually PyCFunctionWithKeywords type, but the base PyMethodDef::ml_meth type
stays PyCFunction.

Previous gccs did not find this, gcc8 now does. Fixing this by silencing this
warning for python.c build.

Commiter notes:

Do not do that for CC=clang, as it breaks the build in some clang
versions, like the ones in fedora up to fedora27:

  fedora:25:error: unknown warning option '-Wno-cast-function-type'; did you mean '-Wno-bad-function-cast'? [-Werror,-Wunknown-warning-option]
  fedora:26:error: unknown warning option '-Wno-cast-function-type'; did you mean '-Wno-bad-function-cast'? [-Werror,-Wunknown-warning-option]
  fedora:27:error: unknown warning option '-Wno-cast-function-type'; did you mean '-Wno-bad-function-cast'? [-Werror,-Wunknown-warning-option]
  #

those have:

  clang version 3.9.1 (tags/RELEASE_391/final)

The one in rawhide accepts that:

  clang version 6.0.0 (tags/RELEASE_600/final)

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Link: http://lkml.kernel.org/r/20180319082902.4518-2-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/setup.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/perf/util/setup.py b/tools/perf/util/setup.py
index 6891635b50c3..001be4f9d3b9 100644
--- a/tools/perf/util/setup.py
+++ b/tools/perf/util/setup.py
@@ -28,6 +28,8 @@ class install_lib(_install_lib):
 cflags = getenv('CFLAGS', '').split()
 # switch off several checks (need to be at the end of cflags list)
 cflags += ['-fno-strict-aliasing', '-Wno-write-strings', '-Wno-unused-parameter' ]
+if cc != "clang":
+    cflags += ['-Wno-cast-function-type' ]
 
 src_perf  = getenv('srctree') + '/tools/perf'
 build_lib = getenv('PYTHON_EXTBUILD_LIB')

  reply	other threads:[~2018-03-20  6:35 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-19  8:29 [PATCH 1/2] perf tools: Fix snprint warnings " Jiri Olsa
2018-03-19  8:29 ` [PATCH 2/2] perf tools: Fix python extension build " Jiri Olsa
2018-03-20  6:34   ` tip-bot for Jiri Olsa [this message]
2018-03-20  6:34 ` [tip:perf/core] perf tools: Fix snprint warnings " tip-bot for Jiri Olsa

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