rust: relax most deny-level lints to warnings

Since we are starting to support several Rust toolchains, lints (including
Clippy ones) now may behave differently and lint groups may include
new lints.

Therefore, to maximize the chances a given version works, relax some
deny-level lints to warnings. It may also make our lives a bit easier
while developing new code or refactoring.

To be clear, the requirements for in-tree code are still the same, since
Rust code still needs to be warning-free (patches should be clean under
`WERROR=y`) and the set of lints is not changed.

`unsafe_op_in_unsafe_fn` is left unmodified, i.e. as an error, since it is
becoming the default in the language (warn-by-default in Rust 2024 [1] and
ideally an error later on) and thus it should also be very well tested. In
addition, it is simple enough that it should not have false positives
(unlike e.g. `rust_2018_idioms`'s `explicit_outlives_requirements`).

`non_ascii_idents` is left unmodified as well, i.e. as an error, since
it is unlikely one gains any productivity during development if it
were a warning (in fact, it may be worse, since it is likely one made
a typo). In addition, it should not have false positives.

Finally, put the two `-D` ones at the top and take the chance to do one
per line.

Link: https://github.com/rust-lang/rust/pull/112038
Reviewed-by: Finn Behrens <me@kloenk.dev>
Tested-by: Benno Lossin <benno.lossin@proton.me>
Tested-by: Andreas Hindborg <a.hindborg@samsung.com>
Link: https://lore.kernel.org/r/20240709160615.998336-5-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

diff --git a/Makefile b/Makefile
index fea263aaa49244a04c59b842c625d0df57314e77..7ea526814fdb7262b5b787419ff552ee7d6c3efb 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -461,17 +461,19 @@ KBUILD_USERLDFLAGS := $(USERLDFLAGS)
 # host programs.
 export rust_common_flags := --edition=2021 \
                            -Zbinary_dep_depinfo=y \
-                           -Dunsafe_op_in_unsafe_fn -Drust_2018_idioms \
-                           -Dunreachable_pub -Dnon_ascii_idents \
+                           -Dunsafe_op_in_unsafe_fn \
+                           -Dnon_ascii_idents \
+                           -Wrust_2018_idioms \
+                           -Wunreachable_pub \
                            -Wmissing_docs \
-                           -Drustdoc::missing_crate_level_docs \
-                           -Dclippy::correctness -Dclippy::style \
-                           -Dclippy::suspicious -Dclippy::complexity \
-                           -Dclippy::perf \
-                           -Dclippy::let_unit_value -Dclippy::mut_mut \
-                           -Dclippy::needless_bitwise_bool \
-                           -Dclippy::needless_continue \
-                           -Dclippy::no_mangle_with_rust_abi \
+                           -Wrustdoc::missing_crate_level_docs \
+                           -Wclippy::correctness -Wclippy::style \
+                           -Wclippy::suspicious -Wclippy::complexity \
+                           -Wclippy::perf \
+                           -Wclippy::let_unit_value -Wclippy::mut_mut \
+                           -Wclippy::needless_bitwise_bool \
+                           -Wclippy::needless_continue \
+                           -Wclippy::no_mangle_with_rust_abi \
                            -Wclippy::dbg_macro
 
 KBUILD_HOSTCFLAGS   := $(KBUILD_USERHOSTCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS)
@@ -572,7 +574,7 @@ KBUILD_RUSTFLAGS := $(rust_common_flags) \
                    -Csymbol-mangling-version=v0 \
                    -Crelocation-model=static \
                    -Zfunction-sections=n \
-                   -Dclippy::float_arithmetic
+                   -Wclippy::float_arithmetic
 
 KBUILD_AFLAGS_KERNEL :=
 KBUILD_CFLAGS_KERNEL :=

diff --git a/rust/Makefile b/rust/Makefile
index 38537831132221415a22b16aebe942c899c1df0c..bf05e65365dad0738822877c2c0fceae8697828a 100644 (file)
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -367,7 +367,7 @@ ifneq ($(or $(CONFIG_ARM64),$(and $(CONFIG_RISCV),$(CONFIG_64BIT))),)
 endif
 
 $(obj)/core.o: private skip_clippy = 1
-$(obj)/core.o: private skip_flags = -Dunreachable_pub
+$(obj)/core.o: private skip_flags = -Wunreachable_pub
 $(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--redefine-sym $(sym)=__rust$(sym))
 $(obj)/core.o: private rustc_target_flags = $(core-cfgs)
 $(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
@@ -381,7 +381,7 @@ $(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE
        +$(call if_changed_dep,rustc_library)
 
 $(obj)/alloc.o: private skip_clippy = 1
-$(obj)/alloc.o: private skip_flags = -Dunreachable_pub
+$(obj)/alloc.o: private skip_flags = -Wunreachable_pub
 $(obj)/alloc.o: private rustc_target_flags = $(alloc-cfgs)
 $(obj)/alloc.o: $(RUST_LIB_SRC)/alloc/src/lib.rs $(obj)/compiler_builtins.o FORCE
        +$(call if_changed_dep,rustc_library)