Avoid passing rustc as second parameter to clippy-driver

It turns out that is only a workaround intended for `cargo`.
The official instructions since PR [1] describe the usage of
`clippy-driver`, and they intentionally only cover replacing
`rustc` with `clippy-driver` rather than wrapping it, as
discussed in that PR.

[1] rust-lang/rust-clippy#6782

Signed-off-by: Miguel Ojeda <[email protected]>

Author: ojeda

Makefile

@@ -525,14 +525,15 @@ KBUILD_LDFLAGS :=
 CLANG_FLAGS :=
 
 ifeq ($(KBUILD_CLIPPY),1)
-	CLIPPY_QUIET_TAG := CLIPPY$(space)
+	RUSTC_OR_CLIPPY_QUIET := CLIPPY
+	RUSTC_OR_CLIPPY = $(CLIPPY_DRIVER)
 else
-	CLIPPY_QUIET_TAG :=
-	CLIPPY_DRIVER :=
+	RUSTC_OR_CLIPPY_QUIET := RUSTC
+	RUSTC_OR_CLIPPY = $(RUSTC)
 endif
-export CLIPPY_QUIET_TAG
+export RUSTC_OR_CLIPPY_QUIET RUSTC_OR_CLIPPY
 
-export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC RUSTC CLIPPY_DRIVER BINDGEN
+export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC RUSTC BINDGEN
 export CPP AR NM STRIP OBJCOPY OBJDUMP READELF PAHOLE RESOLVE_BTFIDS LEX YACC AWK INSTALLKERNEL
 export PERL PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX
 export KGZIP KBZIP2 KLZOP LZMA LZ4 XZ ZSTD

rust/Makefile

@@ -90,9 +90,10 @@ $(objtree)/rust/exports_kernel_generated.h: $(objtree)/rust/kernel.o FORCE
 
 # `-Cpanic=unwind -Cforce-unwind-tables=y` overrides `rustc_flags` in order to
 # avoid the https://github.com/rust-lang/rust/issues/82320 rustc crash.
-quiet_cmd_rustc_procmacro = RUSTC P $(CLIPPY_QUIET_TAG)$@
+quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
       cmd_rustc_procmacro = \
-	$(CLIPPY_DRIVER) $(RUSTC) $(rustc_flags) --emit=dep-info,link --extern proc_macro \
+	$(RUSTC_OR_CLIPPY) $(rustc_flags) \
+		--emit=dep-info,link --extern proc_macro \
 		-Cpanic=unwind -Cforce-unwind-tables=y \
 		--crate-type proc-macro --out-dir $(objtree)/rust/ \
 		--crate-name $(patsubst lib%.so,%,$(notdir $@)) $<; \
@@ -102,11 +103,11 @@ quiet_cmd_rustc_procmacro = RUSTC P $(CLIPPY_QUIET_TAG)$@
 $(objtree)/rust/libmodule.so: $(srctree)/rust/module.rs FORCE
 	$(call if_changed_dep,rustc_procmacro)
 
-quiet_cmd_rustc_library = RUSTC L $(if $(skip_clippy),,$(CLIPPY_QUIET_TAG))$@
+quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L $@
       cmd_rustc_library = \
 	RUST_BINDINGS_FILE=$(abspath $(objtree)/rust/bindings_generated.rs) \
-	$(if $(skip_clippy),,$(CLIPPY_DRIVER)) $(RUSTC) $(rustc_flags) \
-		$(rustc_cross_flags) $(rustc_target_flags) \
+	$(if $(skip_clippy),$(RUSTC),$(RUSTC_OR_CLIPPY)) \
+		$(rustc_flags) $(rustc_cross_flags) $(rustc_target_flags) \
 		--crate-type rlib --out-dir $(objtree)/rust/ -L $(objtree)/rust/ \
 		--crate-name $(patsubst %.o,%,$(notdir $@)) $<; \
 	mv $(objtree)/rust/$(patsubst %.o,%,$(notdir $@)).d $(depfile); \

scripts/Makefile.build

@@ -301,10 +301,10 @@ $(obj)/%.lst: $(src)/%.c FORCE
 
 rustc_cross_flags := --target=$(srctree)/arch/$(SRCARCH)/rust/target.json
 
-quiet_cmd_rustc_o_rs = RUSTC $(CLIPPY_QUIET_TAG)$(quiet_modtag) $@
+quiet_cmd_rustc_o_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
       cmd_rustc_o_rs = \
 	RUST_MODFILE=$(modfile) \
-	$(CLIPPY_DRIVER) $(RUSTC) $(rustc_flags) $(rustc_cross_flags) \
+	$(RUSTC_OR_CLIPPY) $(rustc_flags) $(rustc_cross_flags) \
 		--extern alloc --extern kernel \
 		--crate-type rlib --out-dir $(obj) -L $(objtree)/rust/ \
 		--crate-name $(patsubst %.o,%,$(notdir $@)) $<; \