Subject: linux-next: manual merge of the rust tree with the kbuild tree

From: Stephen Rothwell <[email-masked]>
Date: Thu, 17 Mar 2022 17:02:54 +1100

Hi all,

Today's linux-next merge of the rust tree got a conflict in:

  Makefile

between commit:

  f67695c9962e ("kbuild: Add environment variables for userprogs flags")

from the kbuild tree and commit:

  e2e7cf27b587 ("Kbuild: add Rust support")

from the rust tree.

I fixed it up (see below) and can carry the fix as necessary. This
is now fixed as far as linux-next is concerned, but any non trivial
conflicts should be mentioned to your upstream maintainer when your tree
is submitted for merging.  You may also want to consider cooperating
with the maintainer of the conflicting tree to minimise any particularly
complex conflicts.

-- 
Cheers,
Stephen Rothwell

diff --cc Makefile
index d2269ea42eac,67008a2d964c..000000000000
--- a/Makefile
+++ b/Makefile
@@@ -430,15 -437,32 +437,34 @@@ els
  HOSTCC	= gcc
  HOSTCXX	= g++
  endif
+ HOSTRUSTC = rustc
  
 -export KBUILD_USERCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
 -			      -O2 -fomit-frame-pointer -std=gnu89
 -export KBUILD_USERLDFLAGS :=
 +KBUILD_USERHOSTCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
 +			 -O2 -fomit-frame-pointer -std=gnu11 \
 +			 -Wdeclaration-after-statement
 +KBUILD_USERCFLAGS  := $(KBUILD_USERHOSTCFLAGS) $(USERCFLAGS)
 +KBUILD_USERLDFLAGS := $(USERLDFLAGS)
  
+ # These flags apply to all Rust code in the tree, including the kernel and
+ # 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 \
+ 			    -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 \
+ 			    -Wclippy::dbg_macro
+ 
 -KBUILD_HOSTCFLAGS   := $(KBUILD_USERCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS)
 +KBUILD_HOSTCFLAGS   := $(KBUILD_USERHOSTCFLAGS) $(HOST_LFS_CFLAGS) $(HOSTCFLAGS)
  KBUILD_HOSTCXXFLAGS := -Wall -O2 $(HOST_LFS_CFLAGS) $(HOSTCXXFLAGS)
+ KBUILD_HOSTRUSTFLAGS := $(rust_common_flags) -O -Cstrip=debuginfo \
+ 			-Zallow-features= $(HOSTRUSTFLAGS)
  KBUILD_HOSTLDFLAGS  := $(HOST_LFS_LDFLAGS) $(HOSTLDFLAGS)
  KBUILD_HOSTLDLIBS   := $(HOST_LFS_LIBS) $(HOSTLDLIBS)
  
@@@ -517,12 -549,23 +551,23 @@@ KBUILD_CFLAGS   := -Wall -Wundef -Werro
  		   -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE \
  		   -Werror=implicit-function-declaration -Werror=implicit-int \
  		   -Werror=return-type -Wno-format-security \
 -		   -std=gnu89
 +		   -std=gnu11
  KBUILD_CPPFLAGS := -D__KERNEL__
+ KBUILD_RUSTFLAGS := $(rust_common_flags) \
+ 		    --target=$(objtree)/rust/target.json \
+ 		    -Cpanic=abort -Cembed-bitcode=n -Clto=n \
+ 		    -Cforce-unwind-tables=n -Ccodegen-units=1 \
+ 		    -Csymbol-mangling-version=v0 \
+ 		    -Crelocation-model=static \
+ 		    -Zfunction-sections=n \
+ 		    -Dclippy::float_arithmetic
+ 
  KBUILD_AFLAGS_KERNEL :=
  KBUILD_CFLAGS_KERNEL :=
+ KBUILD_RUSTFLAGS_KERNEL :=
  KBUILD_AFLAGS_MODULE  := -DMODULE
  KBUILD_CFLAGS_MODULE  := -DMODULE
+ KBUILD_RUSTFLAGS_MODULE := --cfg MODULE
  KBUILD_LDFLAGS_MODULE :=
  KBUILD_LDFLAGS :=
  CLANG_FLAGS :=
@@@ -783,9 -858,12 +861,12 @@@ KBUILD_CFLAGS += $(stackp-flags-y
  KBUILD_CFLAGS-$(CONFIG_WERROR) += -Werror
  KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
  
+ KBUILD_RUSTFLAGS-$(CONFIG_WERROR) += -Dwarnings
+ KBUILD_RUSTFLAGS += $(KBUILD_RUSTFLAGS-y)
+ 
  ifdef CONFIG_CC_IS_CLANG
  KBUILD_CPPFLAGS += -Qunused-arguments
 -# The kernel builds with '-std=gnu89' so use of GNU extensions is acceptable.
 +# The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
  KBUILD_CFLAGS += -Wno-gnu
  # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the
  # source of a reference will be _MergedGlobals and not on of the whitelisted names.