From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fengguang Wu Date: Tue, 24 Jul 2012 04:03:27 +0000 Subject: Re: [next:akpm 234/309] lib/rbtree_test.c:107:2: warning: format '%llu' expects argument of type 'lo Message-Id: <20120724040327.GB6957@localhost> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kernel-janitors@vger.kernel.org On Mon, Jul 23, 2012 at 06:14:42PM -0700, Andrew Morton wrote: > On Mon, 23 Jul 2012 17:57:26 -0700 Michel Lespinasse wrote: > > > On Sun, Jul 22, 2012 at 11:50 PM, Fengguang Wu wrote: > > > lib/rbtree_test.c: In function 'rbtree_test_init': > > > lib/rbtree_test.c:107:2: warning: format '%llu' expects argument of type 'long long unsigned int', but argument 2 has type 'cycles_t' [-Wformat] > > > lib/rbtree_test.c: In function 'check': > > > lib/rbtree_test.c:76:4: warning: 'blacks' may be used uninitialized in this function [-Wuninitialized] > > > > Andrew added a cast for the format issue. > > > > Regarding the uninitialized 'blacks' value, gcc is actually wrong > > about it (it will always be initialized on the first loop iteration), > > but we should probably add = 0 on the variable declaration to make gcc > > happy. > > We should use uninitialized_var() if we're going to do that. Because > that avoids adding unneeded instructions and is self-documenting. > > I saw that warning but assumed that later gcc's didn't emit it. If > that was wrong then yes, we should fix it. Andrew, that false warning is emitted by sparc-linux-gcc 4.6.3. gcc-4.7 no longer has this problem. That explains why the x86_64-allmodconfig test didn't complain about it. Hmm, since many cross compilers still use older gcc, I'll ignore -Wuninitialized warnings from them in future. Thanks, Fengguang