rust: deny Clippy warnings globally

This allows to remove the `#[deny(clippy::*)]` lines,
and makes catching Clippy issues in the leaf modules.

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

Author: ojeda

Makefile

@@ -528,6 +528,8 @@ KBUILD_RUSTCFLAGS := --emit=dep-info,obj,metadata --edition=2018 \
 		     -Cforce-unwind-tables=n -Ccodegen-units=1 \
 		     -Zbinary_dep_depinfo=y -Zsymbol-mangling-version=v0 \
 		     -Dunsafe_op_in_unsafe_fn -Wmissing_docs
+KBUILD_CLIPPYFLAGS := -Dclippy::correctness -Dclippy::style \
+		      -Dclippy::complexity -Dclippy::perf
 KBUILD_AFLAGS_KERNEL :=
 KBUILD_CFLAGS_KERNEL :=
 KBUILD_RUSTCFLAGS_KERNEL :=
@@ -540,7 +542,7 @@ CLANG_FLAGS :=
 
 ifeq ($(KBUILD_CLIPPY),1)
 	RUSTC_OR_CLIPPY_QUIET := CLIPPY
-	RUSTC_OR_CLIPPY = $(CLIPPY_DRIVER)
+	RUSTC_OR_CLIPPY = $(CLIPPY_DRIVER) $(KBUILD_CLIPPYFLAGS)
 else
 	RUSTC_OR_CLIPPY_QUIET := RUSTC
 	RUSTC_OR_CLIPPY = $(RUSTC)

rust/compiler_builtins.rs

@@ -25,10 +25,6 @@
 #![compiler_builtins]
 #![no_builtins]
 #![no_std]
-#![deny(clippy::complexity)]
-#![deny(clippy::correctness)]
-#![deny(clippy::perf)]
-#![deny(clippy::style)]
 
 macro_rules! define_panicking_intrinsics(
     ($reason: tt, { $($ident: ident, )* }) => {

rust/kernel/lib.rs

@@ -24,10 +24,6 @@
     receiver_trait,
     try_reserve
 )]
-#![deny(clippy::complexity)]
-#![deny(clippy::correctness)]
-#![deny(clippy::perf)]
-#![deny(clippy::style)]
 #![deny(rust_2018_idioms)]
 
 // Ensure conditional compilation based on the kernel configuration works;

rust/macros/lib.rs

@@ -2,11 +2,6 @@
 
 //! Crate for all kernel procedural macros.
 
-#![deny(clippy::complexity)]
-#![deny(clippy::correctness)]
-#![deny(clippy::perf)]
-#![deny(clippy::style)]
-
 mod module;
 
 use proc_macro::TokenStream;