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

[Lukasz Majewski]

Hi Albert,

> Hi Albert,
> 
> Sorry for a late reply.
> 
> > Hello Lukasz,
> > 
> > On Sat, 22 Nov 2014 07:56:35 +0100, Lukasz Majewski
> > <l.majewski at 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.

On my office PC I've got following gcc:

Using built-in specs.
COLLECT_GCC=gcc
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

I've got a stable debian (Wheezy - 7.4)

> 
> 
> 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


-- 
Best regards,

Lukasz Majewski

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