rust: kbuild: rebuild if .clippy.toml changes

We rarely modify `.clippy.toml`, but currently we do not rebuild if that
happens, thus it is easy to miss possible changes in lints.

Thus rebuild in case of changes.

Cc: [email protected]
Reported-by: Tamir Duberstein <[email protected]>
Closes: Rust-for-Linux#1151
Fixes: 7d56786 ("rust: introduce `.clippy.toml`")
Signed-off-by: Miguel Ojeda <[email protected]>

Author: ojeda

rust/Makefile

@@ -57,6 +57,10 @@ rustdoc_test_quiet=--test-args -q
 rustdoc_test_kernel_quiet=>/dev/null
 endif
 
+ifeq ($(KBUILD_CLIPPY),1)
+	clippy_toml := $(srctree)/.clippy.toml
+endif
+
 core-cfgs = \
     --cfg no_fp_fmt_parse
 
@@ -405,11 +409,12 @@ quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
 		--crate-name $(patsubst lib%.$(libmacros_extension),%,$(notdir $@)) $<
 
 # Procedural macros can only be used with the `rustc` that compiled it.
-$(obj)/$(libmacros_name): $(src)/macros/lib.rs FORCE
+$(obj)/$(libmacros_name): $(src)/macros/lib.rs $(clippy_toml) FORCE
 	+$(call if_changed_dep,rustc_procmacro)
 
 $(obj)/$(libpin_init_internal_name): private rustc_target_flags = --cfg kernel
-$(obj)/$(libpin_init_internal_name): $(src)/pin-init/internal/src/lib.rs FORCE
+$(obj)/$(libpin_init_internal_name): $(src)/pin-init/internal/src/lib.rs \
+    $(clippy_toml) FORCE
 	+$(call if_changed_dep,rustc_procmacro)
 
 quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L $@
@@ -495,7 +500,8 @@ endif
 
 $(obj)/compiler_builtins.o: private skip_gendwarfksyms = 1
 $(obj)/compiler_builtins.o: private rustc_objcopy = -w -W '__*'
-$(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE
+$(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o \
+    $(clippy_toml) FORCE
 	+$(call if_changed_rule,rustc_library)
 
 $(obj)/pin_init.o: private skip_gendwarfksyms = 1