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From:   Asahi Lina <lina@asahilina.net>
Date:   Fri, 14 Jul 2023 18:13:55 +0900
Subject: [PATCH RFC 03/11] rust: Use absolute paths to build Rust objects
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Message-Id: <20230714-classless_lockdep-v1-3-229b9671ce31@asahilina.net>
References: <20230714-classless_lockdep-v1-0-229b9671ce31@asahilina.net>
In-Reply-To: <20230714-classless_lockdep-v1-0-229b9671ce31@asahilina.net>
To:     Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>, Tom Rix <trix@redhat.com>,
        Daniel Vetter <daniel@ffwll.ch>
Cc:     Hector Martin <marcan@marcan.st>, Sven Peter <sven@svenpeter.dev>,
        Alyssa Rosenzweig <alyssa@rosenzweig.io>,
        asahi@lists.linux.dev, rust-for-linux@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
        llvm@lists.linux.dev, Asahi Lina <lina@asahilina.net>
Precedence: bulk

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.

Signed-off-by: Asahi Lina <lina@asahilina.net>
---
 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)

-- 
2.40.1