[RFC PATCH v3 04/22] rust: Kbuild: enable `hex`

[Ariel Miculas <amiculas@xxxxxxxxx>]

With all the new files in place from the hex crate, this patch
adds support for them in the build system.

Signed-off-by: Ariel Miculas <amiculas@xxxxxxxxx>
---
 rust/Makefile          | 24 ++++++++++++++++++++----
 scripts/Makefile.build |  2 +-
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/rust/Makefile b/rust/Makefile
index ca86abac4ed0..fef8e38fbebd 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -15,7 +15,7 @@ always-$(CONFIG_RUST) += libmacros.so
 no-clean-files += libmacros.so
 
 always-$(CONFIG_RUST) += bindings/bindings_generated.rs bindings/bindings_helpers_generated.rs
-obj-$(CONFIG_RUST) += alloc.o bindings.o kernel.o
+obj-$(CONFIG_RUST) += alloc.o bindings.o hex.o kernel.o
 always-$(CONFIG_RUST) += exports_alloc_generated.h exports_bindings_generated.h \
     exports_kernel_generated.h
 
@@ -65,6 +65,15 @@ alloc-cfgs = \
     --cfg no_rc \
     --cfg no_sync
 
+hex-skip_flags := \
+    --edition=2021 \
+    -Drust_2018_idioms \
+    -Dunreachable_pub
+
+hex-flags := \
+    --edition=2018 \
+    -Amissing_docs
+
 quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
       cmd_rustdoc = \
 	OBJTREE=$(abspath $(objtree)) \
@@ -455,10 +464,17 @@ $(obj)/uapi.o: $(src)/uapi/lib.rs \
     $(obj)/uapi/uapi_generated.rs FORCE
 	+$(call if_changed_dep,rustc_library)
 
+$(obj)/hex.o: private skip_clippy = 1
+$(obj)/hex.o: private skip_flags = $(hex-skip_flags)
+$(obj)/hex.o: private rustc_target_flags = $(hex-flags)
+$(obj)/hex.o: $(src)/hex/lib.rs $(obj)/compiler_builtins.o FORCE
+	$(call if_changed_dep,rustc_library)
+
 $(obj)/kernel.o: private rustc_target_flags = --extern alloc \
-    --extern build_error --extern macros --extern bindings --extern uapi
+    --extern build_error --extern macros --extern bindings --extern uapi \
+    --extern hex
 $(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(obj)/build_error.o \
-    $(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o FORCE
-	+$(call if_changed_dep,rustc_library)
+    $(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o $(obj)/hex.o FORCE
+	$(call if_changed_dep,rustc_library)
 
 endif # CONFIG_RUST
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 367cfeea74c5..2e9a64224c51 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -273,7 +273,7 @@ rust_common_cmd = \
 	-Zallow-features=$(rust_allowed_features) \
 	-Zcrate-attr=no_std \
 	-Zcrate-attr='feature($(rust_allowed_features))' \
-	--extern alloc --extern kernel \
+	--extern alloc --extern kernel --extern hex \
 	--crate-type rlib -L $(objtree)/rust/ \
 	--crate-name $(basename $(notdir $@)) \
 	--sysroot=/dev/null \
-- 
2.34.1