Re: [PATCH] selftests/binderfs: use the Makefile's rules, not Make's implicit rules

[Shuah Khan]

On 5/3/24 03:10, Christian Brauner wrote:
> On Thu, May 02, 2024 at 06:58:20PM -0700, John Hubbard wrote:
> > First of all, in order to build with clang at all, one must first apply
> > Valentin Obst's build fix for LLVM [1]. Once that is done, then when
> > building with clang, via:
> >
> >      make LLVM=1 -C tools/testing/selftests
> >
> > ...the following error occurs:
> >
> >     clang: error: cannot specify -o when generating multiple output files
> >
> > This is because clang, unlike gcc, won't accept invocations of this
> > form:
> >
> >      clang file1.c header2.h
> >
> > While trying to fix this, I noticed that:
> >
> > a) selftests/lib.mk already avoids the problem, and
> >
> > b) The binderfs Makefile indavertently bypasses the selftests/lib.mk
> > build system, and quitely uses Make's implicit build rules for .c files
> > instead.
> >
> > The Makefile attempts to set up both a dependency and a source file,
> > neither of which was needed, because lib.mk is able to automatically
> > handle both. This line:
> >
> >      binderfs_test: binderfs_test.c
> >
> > ...causes Make's implicit rules to run, which builds binderfs_test
> > without ever looking at lib.mk.
> >
> > Fix this by simply deleting the "binderfs_test:" Makefile target and
> > letting lib.mk handle it instead.
> >
> > [1] https://lore.kernel.org/all/20240329-selftests-libmk-llvm-rfc-v1-1-2f9ed7d1c49f@xxxxxxxxxxxxxxx/
> >
> > Fixes: 6e29225af902 ("binderfs: port tests to test harness infrastructure")
> > Cc: Christian Brauner <brauner@xxxxxxxxxx>
> > Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
> > ---
>
> Reviewed-by: Christian Brauner <brauner@xxxxxxxxxx>

Thank you. Applied to linunx-kselftest next for Linux 6.10-rc1

thanks,
-- Shuah