Re: warning from gcc version 4.6.0 20100416

From: Bill Davidsen
Date: Mon Jun 14 2010 - 10:51:21 EST

Andi Kleen wrote:
On Sun, Jun 13, 2010 at 09:17:41PM -0400, Bill Davidsen wrote:
Justin P. Mattock wrote:
o.k. andi,

here is the rest of the warnings that
I see when compiling the kernel

I can try and create some patches for

There is no great solution to this, in a fair number of cases the fix would slow the code or make it harder to read, so some of these probably don't

Sorry that's wrong: the optimizer will generate the same
code anyways as if the unused variable was not there
because it eliminates unused variables.

If one puts an 'if' around the variable set (I've seen it) the test may well take longer than the assign, assuming that there's a case where the assign is done.
So fixing this cannot make code slower.

I also don't see how unused variables make the code easier to read.

No, my point was that putting a bunch of ifdef statements in to avoid the warning will make the code harder to read.

The only difficult case sometimes is with #ifdef code,
that has to be handled case by case. One elegant solution
is to replace the ifdef code with an inline.

want a fix. Of course some clearly are errors, so you are doing something

All warnings should be fixed, I only left those in that are real code bugs if I couldn't fix the code.

Kernel builds are expected to be relatively warning free
so that you can easily spot new warnings.

But eventually someone who knows the code better has to
fix that bug.


Bill Davidsen <davidsen@xxxxxxx>
"We can't solve today's problems by using the same thinking we
used in creating them." - Einstein

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