Re: [PATCH] rust: Respect HOSTCC when linking for host

[Finn Behrens]

On 15 Sep 2023, at 19:28, Matthew Maurer wrote:

> Currently, rustc defaults to invoking `cc`, even if `HOSTCC` is defined,
> resulting in build failures in hermetic environments where `cc` does not
> exist. This includes both hostprogs and proc-macros.
>
> Since we are setting the linker to `HOSTCC`, we set the linker flavor to
> `gcc` explicitly.
But as `HOSTCC` could also be clang, the linker flavor would then be wrong, would that create a problem?
>
> Signed-off-by: Matthew Maurer <mmaurer@xxxxxxxxxx>
> ---
>  rust/Makefile         | 1 +
>  scripts/Makefile.host | 1 +
>  2 files changed, 2 insertions(+)
>
> diff --git a/rust/Makefile b/rust/Makefile
> index 87958e864be0..2a2352638f11 100644
> --- a/rust/Makefile
> +++ b/rust/Makefile
> @@ -383,6 +383,7 @@ $(obj)/exports_kernel_generated.h: $(obj)/kernel.o FORCE
>  quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
>        cmd_rustc_procmacro = \
>  	$(RUSTC_OR_CLIPPY) $(rust_common_flags) \
> +		-C linker-flavor=gcc -C linker=$(HOSTCC) \
>  		--emit=dep-info=$(depfile) --emit=link=$@ --extern proc_macro \
>  		--crate-type proc-macro \
>  		--crate-name $(patsubst lib%.so,%,$(notdir $@)) $<
> diff --git a/scripts/Makefile.host b/scripts/Makefile.host
> index 8f7f842b54f9..0aa95a3af1c4 100644
> --- a/scripts/Makefile.host
> +++ b/scripts/Makefile.host
> @@ -91,6 +91,7 @@ hostcxx_flags  = -Wp,-MMD,$(depfile) \
>  # current working directory, which may be not accessible in the out-of-tree
>  # modules case.
>  hostrust_flags = --out-dir $(dir $@) --emit=dep-info=$(depfile) \
> +		 -C linker-flavor=gcc -C linker=$(HOSTCC) \
>                   $(KBUILD_HOSTRUSTFLAGS) $(HOST_EXTRARUSTFLAGS) \
>                   $(HOSTRUSTFLAGS_$(target-stem))
>
> -- 
> 2.42.0.459.ge4e396fd5e-goog