Re: [PATCH 1/1] tools build: Fix rust feature detection

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Tue, Feb 10, 2026 at 11:02:56AM +0100, Dmitry Dolgov wrote:
> > On Mon, Feb 09, 2026 at 02:27:43PM -0300, Arnaldo Carvalho de Melo wrote:
> > Features in FEATURE_TESTS_BASIC will be set as being available if
> > test-all.c builds, so since the rust test isn't included in test-all.c,
> > we can't have 'rust' in there, remove it from FEATURE_TESTS_BASIC and
> > use feature-check so that it tries to build test-rust.bin, doing the
> > actual feature detection.
> 
> My bad, thanks for fixing it.
> 
> > And after installing it:
> > 
> >   ...                                    rust: [ on  ]
> > 
> >   $ cat /tmp/build/perf-tools-next/feature/test-rust.make.output
> >   $ file /tmp/build/perf-tools-next/feature/test-rust.bin
> > /tmp/build/perf-tools-next/feature/test-rust.bin: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=9c416edf673ee3705b97bae893a99a6fcf1ee258, for GNU/Linux 3.2.0, with debug_info, not stripped
> >   $
> >   $ perf -vv | grep RUST
> >                   rust: [ on  ]  # HAVE_RUST_SUPPORT
> 
> I've noticed few more problem, maybe worth fixing it here as well:
> 
> * test-rust.bin is missing from the list of FILES, and thus is not removed by
> the clean target. This could lead to a false feature detection, since the
> binary stays there.
> 
> * Target to build test-rust.bin does not emit a dependencies file.
> 
> I've tested the following diff after first having rust installed, then removing
> it and building again.


I'll add it with your Signed-off-by, etc, please submit as a complete
patch next time :-)

- Arnaldo
 
> diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
> index 9ae69d85716..28d4ff0841a 100644
> --- a/tools/build/feature/Makefile
> +++ b/tools/build/feature/Makefile
> @@ -73,7 +73,8 @@ FILES=                                          \
>           test-clang-bpf-co-re.bin              \
>           test-file-handle.bin                  \
>           test-libpfm4.bin                      \
> -         test-libopenssl.bin
> +         test-libopenssl.bin                   \
> +         test-rust.bin
> 
>  FILES := $(addprefix $(OUTPUT),$(FILES))
> 
> @@ -112,7 +113,7 @@ __BUILD = $(CC) $(CFLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.c,$(@F)) $(
>  __BUILDXX = $(CXX) $(CXXFLAGS) -MD -Wall -Werror -o $@ $(patsubst %.bin,%.cpp,$(@F)) $(LDFLAGS)
>    BUILDXX = $(__BUILDXX) > $(@:.bin=.make.output) 2>&1
> 
> -__BUILDRS = $(RUSTC) $(RUSTC_FLAGS) -o $@ $(patsubst %.bin,%.rs,$(@F))
> +__BUILDRS = $(RUSTC) $(RUSTC_FLAGS) --emit=dep-info=$(patsubst %.bin,%.d,$(@F)),link -o $@ $(patsubst %.bin,%.rs,$(@F))
>    BUILDRS = $(__BUILDRS) > $(@:.bin=.make.output) 2>&1
> 
> Reviewed-by: Dmitrii Dolgov <9erthalion6@gmail.com>