[U-Boot] [PATCH 1/2] Makefile: fix clang warnings due to clang support

[Jeroen Hofstee]

Hello Masahiro,

On di, 2014-06-10 at 21:20 +0900, Masahiro Yamada wrote:
> Hi Jeroen,
> 
> 
> On Fri, 30 May 2014 15:45:27 +0200
> Jeroen Hofstee <jeroen at myspectrum.nl> wrote:
> 
> > Building u-boot tools with clang as a host compiler e.g. on
> > FreeBSD with `gmake HOSTCC=clang CONFIG_USE_PRIVATE_LIBGCC=y tools`
> > leads to many warnings [1] for every compiler invocation since
> > commit 598e2d33. Part of mentioned commit imports linux patches:
> > 
> >  - kbuild: LLVMLinux: Adapt warnings for compilation with clang
> >  - kbuild: LLVMLinux: Add Kbuild support for building kernel with Clang
> > 
> > No version of clang supports the gcc fno-delete-null-pointer-checks
> > though, but it is only passed to clang. Gcc does not have the clang
> > specific Qunused-arguments for the target. Furthermore several
> > warnings are disabled which aren't encountered in u-boot. Since such
> > a build has worked for quite some time and works after removing these
> > changes, just remove the clang specific handling to restore normal
> > building with clang as hostcc.
> 
> 
> 
> I have to admit I just copied these line from Kernel
> without testing it, just for syncing with Kernel makefiles.
> 
> 
> As far as I tested, Clang did not recognize 
> -fno-delete-null-pointer-checks.
> 
> It is OK with me if you rip Clang stuff off the top Makefile.
> 
> Sorry, honestly I am not familiar enough with Clang
> to make deeper review.

yup, it should be removed.. since with clang 3.5 trunk it actually
errors. You should be able to verify it without cross target support
with:

`make CC="clang -no-integrated-as" HOSTCC="clang -no-integrated-as"
HOST_TOOLS_ALL=y sandbox_config tools`

and you get (with clang 3.5) "clang: error: unknown argument:
'-fno-delete-null-pointer-checks'" (and yes the commit mentions warns,
which more then likely is the case for clang 3.3 / 3.4). Undoing the
Linux clang additions (as this patch does) makes the build work again.

Since there is no target clang support in U-boot at the moment the
target warnings suppression can be removed as well, since it is just
dead code at the moment and I would like to see how far we can get with
actually fixing warnings, not blindly silencing them...

Regards,
Jeroen