Re: [PATCH] rust: Suppress searching builtin sysroot

[Boqun Feng]

[Cc Catalin as well]

On Tue, Oct 31, 2023 at 08:10:14PM +0000, Matthew Maurer wrote:
> By default, if Rust is passed `--target=foo` rather than a target.json
> file, it will infer a default sysroot if that component is installed. As
> the proposed aarch64 support uses `aarch64-unknown-none` rather than a
> target.json file, this is needed to prevent rustc from being confused
> between the custom kernel sysroot and the pre-installed one.
> 
> Signed-off-by: Matthew Maurer <mmaurer@xxxxxxxxxx>
> ---
> 
> This patch is prompted by the issue I encountered at
> https://lore.kernel.org/all/CAGSQo01pOixiPXkW867h4vPUaAjtKtHGKhkV-rpifJvKxAf4Ww@xxxxxxxxxxxxxx/
> but should be generically more hermetic even if we don't end up landing
> that patch.
> 

I'm able to reproduce the issue you mentioned here after
`rustup target add aarch64-unknown-none`, and your patch fixed that.

Tested-by: Boqun Feng <boqun.feng@xxxxxxxxx>

Regards,
Boqun

>  rust/Makefile          | 1 +
>  scripts/Makefile.build | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/rust/Makefile b/rust/Makefile
> index a27f35f924ec..0403e88e19fd 100644
> --- a/rust/Makefile
> +++ b/rust/Makefile
> @@ -400,6 +400,7 @@ quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L
>  		--emit=metadata=$(dir $@)$(patsubst %.o,lib%.rmeta,$(notdir $@)) \
>  		--crate-type rlib -L$(objtree)/$(obj) \
>  		--crate-name $(patsubst %.o,%,$(notdir $@)) $< \
> +		--sysroot=/dev/null \
>  	$(if $(rustc_objcopy),;$(OBJCOPY) $(rustc_objcopy) $@)
>  
>  rust-analyzer:
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 82e3fb19fdaf..6e4ee513cc3c 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -275,6 +275,7 @@ rust_common_cmd = \
>  	--extern alloc --extern kernel \
>  	--crate-type rlib -L $(objtree)/rust/ \
>  	--crate-name $(basename $(notdir $@)) \
> +	--sysroot=/dev/null \
>  	--out-dir $(dir $@) --emit=dep-info=$(depfile)
>  
>  # `--emit=obj`, `--emit=asm` and `--emit=llvm-ir` imply a single codegen unit
> -- 
> 2.42.0.820.g83a721a137-goog
>