Re: [PATCH RFC 03/11] rust: Use absolute paths to build Rust objects

[Gary Guo]

On Fri, 14 Jul 2023 18:13:55 +0900
Asahi Lina <lina@xxxxxxxxxxxxx> wrote:

> We want to use caller_location to uniquely identify callsites, to
> automatically create lockdep classes without macros. The location
> filename in local code uses the relative path passed to the compiler,
> but if that code is generic and instantiated from another crate, the
> path becomes absolute.
> 
> To make this work and keep the paths consistent, always pass an absolute
> path to the compiler. Then the Location path is always identical
> regardless of how the code is being compiled.

I wonder if this can have some reproducible build implications. We
probably also need to use remap-path-prefix?

> 
> Signed-off-by: Asahi Lina <lina@xxxxxxxxxxxxx>
> ---
>  rust/Makefile          | 2 +-
>  scripts/Makefile.build | 8 ++++----
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/rust/Makefile b/rust/Makefile
> index 7c9d9f11aec5..552f023099c8 100644
> --- a/rust/Makefile
> +++ b/rust/Makefile
> @@ -369,7 +369,7 @@ quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L
>  		--emit=dep-info=$(depfile) --emit=obj=$@ \
>  		--emit=metadata=$(dir $@)$(patsubst %.o,lib%.rmeta,$(notdir $@)) \
>  		--crate-type rlib -L$(objtree)/$(obj) \
> -		--crate-name $(patsubst %.o,%,$(notdir $@)) $< \
> +		--crate-name $(patsubst %.o,%,$(notdir $@)) $(abspath $<) \
>  	$(if $(rustc_objcopy),;$(OBJCOPY) $(rustc_objcopy) $@)
>  
>  rust-analyzer:
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 6413342a03f4..c925b90ebd80 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -283,27 +283,27 @@ rust_common_cmd = \
>  # would not match each other.
>  
>  quiet_cmd_rustc_o_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
> -      cmd_rustc_o_rs = $(rust_common_cmd) --emit=obj=$@ $<
> +      cmd_rustc_o_rs = $(rust_common_cmd) --emit=obj=$@ $(abspath $<)
>  
>  $(obj)/%.o: $(src)/%.rs FORCE
>  	$(call if_changed_dep,rustc_o_rs)
>  
>  quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
>        cmd_rustc_rsi_rs = \
> -	$(rust_common_cmd) -Zunpretty=expanded $< >$@; \
> +	$(rust_common_cmd) -Zunpretty=expanded $(abspath $<) >$@; \
>  	command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) $@
>  
>  $(obj)/%.rsi: $(src)/%.rs FORCE
>  	$(call if_changed_dep,rustc_rsi_rs)
>  
>  quiet_cmd_rustc_s_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
> -      cmd_rustc_s_rs = $(rust_common_cmd) --emit=asm=$@ $<
> +      cmd_rustc_s_rs = $(rust_common_cmd) --emit=asm=$@ $(abspath $<)
>  
>  $(obj)/%.s: $(src)/%.rs FORCE
>  	$(call if_changed_dep,rustc_s_rs)
>  
>  quiet_cmd_rustc_ll_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
> -      cmd_rustc_ll_rs = $(rust_common_cmd) --emit=llvm-ir=$@ $<
> +      cmd_rustc_ll_rs = $(rust_common_cmd) --emit=llvm-ir=$@ $(abspath $<)
>  
>  $(obj)/%.ll: $(src)/%.rs FORCE
>  	$(call if_changed_dep,rustc_ll_rs)
>