Problem building kernel 4.0 with gcc5 Werror

Problem building kernel 4.0 with gcc5 Werror

[Victor Rodriguez]

Hi everyone

I am trying to build the kernel 4.0 with gcc 5 . But I found the
following problem :

builtin-report.c comparison of constant ?-1? with boolean expression
is always false

THe problem is that gcc5 has new warnings:

A new command-line option -Wbool-compare has been added for the C and
C++ compilers, which warns about boolean expressions compared with an
integer value different from true/false.
https://gcc.gnu.org/gcc-5/changes.html

I was checking the Makefile of tools/perf/ anda aprently they became
every warning into an error. Werror

Now I wonder if someone is working on this changes so I can take their pathces.

Do you know any easy way that GCC use to avoid this kind of problems

All the help is more than welcome

Regards

Victor Rodriguez

Problem building kernel 4.0 with gcc5 Werror

[Paul Bolle]

On Sat, 2015-05-09 at 18:28 -0500, Victor Rodriguez wrote:
> I am trying to build the kernel 4.0 with gcc 5 . But I found the
> following problem :
> 
> builtin-report.c comparison of constant ?-1? with boolean expression
> is always false
> 
> THe problem is that gcc5 has new warnings:
> 
> A new command-line option -Wbool-compare has been added for the C and
> C++ compilers, which warns about boolean expressions compared with an
> integer value different from true/false.
> https://gcc.gnu.org/gcc-5/changes.html

I think the problem is actually that the code is broken. See commit
fefd2d9619de ("perf report: Fix branch stack mode cannot be set") in
linux-next which links to
http://lkml.kernel.org/r/1423967617-28879-1-git-send-email-hekuang at huawei.com . 
 
> I was checking the Makefile of tools/perf/ anda aprently they became
> every warning into an error. Werror

(tools/perf/Makefile.perf has this line
    # Define WERROR=0 to disable treating any warnings as errors.

Perhaps that might help you get past this build error. I don't know, I
never tried it. But the best thing here seems to use that patch. I guess
it should eventually show up in the v4.0.y-stable tree.)

> Now I wonder if someone is working on this changes so I can take their pathces.
> 
> Do you know any easy way that GCC use to avoid this kind of problems
> 
> All the help is more than welcome

Hope this helps,


Paul Bolle