[PATCH v8 27/31] Kbuild: add Rust support

[Arnd Bergmann]

On Tue, Aug 2, 2022 at 3:50 AM Miguel Ojeda <ojeda at kernel.org> wrote:
>
> +# These flags apply to all Rust code in the tree, including the kernel and
> +# host programs.
> +export rust_common_flags := --edition=2021 \
> +                           -Zbinary_dep_depinfo=y \
> +                           -Dunsafe_op_in_unsafe_fn -Drust_2018_idioms \
> +                           -Dunreachable_pub -Dnon_ascii_idents \
> +                           -Wmissing_docs \
> +                           -Drustdoc::missing_crate_level_docs \
> +                           -Dclippy::correctness -Dclippy::style \
> +                           -Dclippy::suspicious -Dclippy::complexity \
> +                           -Dclippy::perf \
> +                           -Dclippy::let_unit_value -Dclippy::mut_mut \
> +                           -Dclippy::needless_bitwise_bool \
> +                           -Dclippy::needless_continue \
> +                           -Wclippy::dbg_macro

Hi Miguel,

I tried enabling rust support in the gcc builds I provide at
https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/arm64/12.1.0/
to make this more accessible, but it appears that the command line
options here are not portable:

 /home/arnd/cross/x86_64/gcc-12.1.0+rust-nolibc/x86_64-linux/bin/x86_64-linux-gccrs
--edition=2021 -Zbinary_dep_depinfo=y -Dunsafe_op_in_unsafe_fn
-Drust_2018_idioms -Dunreachable_pub -Dnon_ascii_idents -Wmissing_docs
-Drustdoc::missing_crate_level_docs -Dclippy::correctness
-Dclippy::style -Dclippy::suspicious -Dclippy::complexity
-Dclippy::perf -Dclippy::let_unit_value -Dclippy::mut_mut
-Dclippy::needless_bitwise_bool -Dclippy::needless_continue
-Wclippy::dbg_macro -O -Cstrip=debuginfo -Zallow-features=
--emit=dep-info,link --out-dir=scripts/
/git/arm-soc/scripts/generate_rust_target.rs; mv
scripts/generate_rust_target.d scripts/.generate_rust_target.d; sed -i
'/^#/d' scripts/.generate_rust_target.d
x86_64-linux-gccrs: error: unrecognized command-line option
'--edition=2021'; did you mean '-frust-edition=2021'?
x86_64-linux-gccrs: error: unrecognized command-line option
'-Zbinary_dep_depinfo=y'
x86_64-linux-gccrs: error: unrecognized command-line option
'-Wmissing_docs'; did you mean '-Wmissing-braces'?
x86_64-linux-gccrs: error: unrecognized command-line option
'-Wclippy::dbg_macro'
x86_64-linux-gccrs: error: unrecognized command-line option '-Cstrip=debuginfo'
x86_64-linux-gccrs: error: unrecognized command-line option '-Zallow-features='
x86_64-linux-gccrs: error: unrecognized command-line option
'--emit=dep-info,link'
x86_64-linux-gccrs: error: unrecognized command-line option '--out-dir=scripts/'
make[3]: *** [/git/arm-soc/scripts/Makefile.host:157:
scripts/generate_rust_target] Error 1

I guess nobody has tried this so far. Would you think that fixing this is only
a matter for fixing the build system to pass the correct flags depending on the
compiler, or is this broken in a more fundamental way?

         Arnd