Messages in this thread | | | Date | Tue, 27 Jan 2009 14:06:08 +0100 | From | Ingo Molnar <> | Subject | Re: [2.6.29-rc2-git2] compilation warnings |
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* Jean Delvare <khali@linux-fr.org> wrote:
> Hi Takashi, > > On Tue, 27 Jan 2009 10:34:20 +0100, Takashi Iwai wrote: > > At Tue, 27 Jan 2009 09:46:28 +0100, > > > On Tue, 27 Jan 2009 08:32:17 +0100, Takashi Iwai wrote: > > > > A bogus warning. Ignore this. > > > > > > No matter how bogus it is, it should be fixed. Otherwise this is > > > wasting the time of users and developers over and over again. > > > > Well, it's a bug of gcc appearing only in a certain version, so most > > people won't see it. > > > > Of course, we can put uninitialized_var(). But, I don't basically > > like adding it unconditionally... > > I didn't know about uninitialized_var(), thanks for the hint. > > My experience with these warnings is that, in many cases, it is possible > to write the code differently so that it is clear to the compiler that > the variable is never used uninitialized. In some cases, doing so also > makes the code easier to read for humans and less likely to break in the > future. > > Of course, in some cases the problem is simply that the compiler is too > stupid to understand even simple things, but in other cases these > warnings might be a good opportunity to rewrite the code in a way that > is easier to understand.
And even in the cases where the compiler is stupid, leaving a warning around:
1) Does not get compiler bugs fixed any faster [only true competition between compilers gets compiler bugs fixed any faster]
2) Has ongoing and irreversible maintenance costs for _all of us in the kernel_
3) for every bogus compiler warning there's a dozen warnings where the compiler told us that _we_ were doing something stupid. All things considered the false positive ratio is still a fair deal.
So leaving them around is a bit like making a political point by burning yourself in front of the cameras - leaves the political opponent largely unimpressed and unscathed while being self-destructive in 99% of the cases.
gcc_is_utterly_stupid(var) type of annotations (that initialize to zero instead of the current 'turn off the warning' dangerous construct) would be far better. Albeit even that would in all likelyhood be a rather pointless (but admittedly satisfying) gesture.
Ingo
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