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rust: kbuild: use pound to support GNU Make < 4.3

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GNU Make 4.3 changed the behavior of `#` inside commands in commit
c6966b323811 ("[SV 20513] Un-escaped # are not comments in function
invocations"):

    * WARNING: Backward-incompatibility!
      Number signs (#) appearing inside a macro reference or function invocation
      no longer introduce comments and should not be escaped with backslashes:
      thus a call such as:
        foo := $(shell echo '#')
      is legal.  Previously the number sign needed to be escaped, for example:
        foo := $(shell echo '\#')
      Now this latter will resolve to "\#".  If you want to write makefiles
      portable to both versions, assign the number sign to a variable:
        H := \#
        foo := $(shell echo '$H')
      This was claimed to be fixed in 3.81, but wasn't, for some reason.
      To detect this change search for 'nocomment' in the .FEATURES variable.

Unlike other commits in the kernel about this issue, such as commit
633174a704 ("lib/raid6/test/Makefile: Use $(pound) instead of \#
for Make 4.3"), that fixed the issue for newer GNU Makes, in our case
it was the opposite, i.e. we need to fix it for the older ones: someone
building with e.g. 4.2.1 gets the following error:

    scripts/Makefile.compiler:81: *** unterminated call to function 'call': missing ')'.  Stop.

Thus use the existing variable to fix it.

Reported-by: moyi geek <1441339168@qq.com>
Closes: https://rust-for-linux.zulipchat.com/#narrow/channel/291565/topic/x/near/512001985
Cc: stable@vger.kernel.org
Fixes: e72a076c62 ("kbuild: fix issues with rustc-option")
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250414171241.2126137-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Miguel Ojeda 2025-04-14 19:12:41 +02:00
parent a3cd5f507b
commit 1c4494c14b
1 changed files with 1 additions and 1 deletions
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2
scripts/Makefile.compiler
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@ -79,7 +79,7 @@ ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3))
# Usage: MY_RUSTFLAGS += $(call __rustc-option,$(RUSTC),$(MY_RUSTFLAGS),-Cinstrument-coverage,-Zinstrument-coverage)
# TODO: remove RUSTC_BOOTSTRAP=1 when we raise the minimum GNU Make version to 4.4
__rustc-option = $(call try-run,\
echo '#![allow(missing_docs)]#![feature(no_core)]#![no_core]' | RUSTC_BOOTSTRAP=1\
echo '$(pound)![allow(missing_docs)]$(pound)![feature(no_core)]$(pound)![no_core]' | RUSTC_BOOTSTRAP=1\
$(1) --sysroot=/dev/null $(filter-out --sysroot=/dev/null --target=%,$(2)) $(3)\
--crate-type=rlib --out-dir=$(TMPOUT) --emit=obj=- - >/dev/null,$(3),$(4))