[U-Boot] [PATCH] fix: tools: kwbimage.c: Initialize headersz to suppress warning

Lukasz Majewski
2014-11-23T17:38:15Z

Hi Albert,

Sorry for a late reply.

> Hello Lukasz,
>
> On Sat, 22 Nov 2014 07:56:35 +0100, Lukasz Majewski
> <l.majewski@majess.pl> wrote:
>
> > > Agreed in general, but not for this one, since "fixing" is the
> > > carpet,
> >
> > I assume that you are presenting below an answer to a "general"
> > case.
> >
> > However, as Thomas pointed out earlier, this "fix" is perfectly safe
> > regarding the underlying kwbimage code.
>
> Jeroen and I (full disclaimer: we have discussed the topic on IRC)
> do not contend that the proposed fix would be unsafe; it *is* safe,
> i.e. it does not adversely affect the code behavior in any measurable
> way.
>
> What we contend is that the fix be the /right/ fix (although Jeroen
> and I have slightly differing criteria for defining what "the right
> fix" would be).
>
> > > > and
> > > > the only justification I see as acceptable for doing so is when
> > > > leaving the warning enabled would cause an obnoxiously high
> > > > number of false positives.
> > >
> > > Well let me add, if "fixing the warning" causes real error
> > > to be hidden, we shouldn't "fix" the warnings by modifying
> > > valid code.
> >
> > Each subsequent "fix" for this kind of warning should be considered
> > case by case IMHO, therefore I agree with Albert.
>
> Jeroen also agreed on IRC that disabling the compiler warning is not
> the right fix either; and I agreed that there had to be a better fix
> than pseudo-initializing headersz. I therefore suggested refactoring
> kwbimage_set_header in order to ensure gcc does not emit the warning,
> but without resorting to non-functional code such as a functionally
> meaningless initialization.
>
> Problem is, to refactor the code, one needs a gcc which emits the
> warnig. I tried various versions of gcc (4.7.4, 4.8.3, 4.9.1) and all
> remained silent when compiling tools/kwbimage.c.
>
> Hence my request: Lukasz, which toolchain are you using exactly? Where
> can we download it from?

The warning appear on my personal laptop too:

lukma at jawa:~/work/embedded/u-boot-denx (master)$ cc -v
Using built-in specs.
COLLECT_GCC=cc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.7.2-5'
--with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs
--enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.7 --enable-shared --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--enable-gnu-unique-object --enable-plugin --enable-objc-gc
--with-arch-32=i586 --with-tune=generic --enable-checking=release
--build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu Thread model: posix gcc version 4.7.2 (Debian
4.7.2-5)

HOSTCC tools/kwbimage.o
tools/kwbimage.c: In function ?kwbimage_set_header?:
tools/kwbimage.c:803:8: warning: ?headersz? may be used uninitialized
in this function [-Wmaybe-uninitialized]

Debian distro: version 7.6 (Wheezy)

I will check the exact gcc on my office PC tomorrow.

Heiko also complained about this Warning. Heiko could you also share
information about your setup?

>
> > > Regards,
> > > Jeroen
> >
> > Best regards,
> > Lukasz Majewski
>
> Amicalement,

Best regards,
Lukasz Majewski
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