Re: [PATCH] Fix an "variable might be used uninitialized" gcc warning

From: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Date: Jan 31, 2012, 18:36 UTC
Message-ID: <4F2834AD.20004@ramsay1.demon.co.uk>
In-Reply-To: <20111216235908.GA5858@elie.hsd1.il.comcast.net>

Jonathan Nieder wrote:

Show 13 quoted lines

> Ramsay Jones wrote:
> 
>>         CC builtin/checkout.o
>>     builtin/checkout.c: In function `cmd_checkout':
>>     builtin/checkout.c:160: warning: 'mode' might be used uninitialized \
>>         in this function
> [...]
>> [Note that only 2 out of the 3 versions of gcc I use issues this
>> warning]
> 
> Which version of gcc is that?  Is gcc getting more sane, so we won't
> have to worry about this after a while, or is the false positive a
> new regression that should be reported to them?

[Sorry for the late reply, I've been away from email for several weeks...]

The versions which complain are 3.4.4 and 4.1.2, whereas 4.4.0 compiles the code without complaint. So, gcc *may* be getting more sane, but I wouldn't bet on it! :-P

I've had examples of this kind of warning, which relies heavily on the analysis performed primarily for the optimizer, come-and-go in gcc before; so don't hold your breath (this is the most volatile part of the compiler).

Having said that, unless you are going to decree that the project only supports gcc (and presumably only some particular versions of gcc), then you may well find similar warnings triggered when using other compilers anyway ...

ATB, Ramsay Jones