[PATCH] kbuild: rust: remove unneeded `@rustc_cfg` to avoid ICE

[Miguel Ojeda]

When KUnit tests are enabled, under very big kernel configurations
(e.g. `allyesconfig`), we can trigger a `rustdoc` ICE [1]:

      RUSTDOC TK rust/kernel/lib.rs
    error: the compiler unexpectedly panicked. this is a bug.

The reason is that this build step has a duplicated `@rustc_cfg` argument,
which contains the kernel configuration, and thus a lot of arguments. The
factor 2 happens to be enough to reach the ICE.

Thus remove the unneeded `@rustc_cfg`. By doing so, we clean up the
command and workaround the ICE.

The ICE has been fixed in the upcoming Rust 1.79 [2].

Cc: stable@xxxxxxxxxxxxxxx
Fixes: a66d733da801 ("rust: support running Rust documentation tests as KUnit ones")
Link: https://github.com/rust-lang/rust/issues/122722 [1]
Link: https://github.com/rust-lang/rust/pull/122840 [2]
Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx>
---
 rust/Makefile | 1 -
 1 file changed, 1 deletion(-)

diff --git a/rust/Makefile b/rust/Makefile
index 846e6ab9d5a9..86a125c4243c 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -175,7 +175,6 @@ quiet_cmd_rustdoc_test_kernel = RUSTDOC TK $<
 	mkdir -p $(objtree)/$(obj)/test/doctests/kernel; \
 	OBJTREE=$(abspath $(objtree)) \
 	$(RUSTDOC) --test $(rust_flags) \
-		@$(objtree)/include/generated/rustc_cfg \
 		-L$(objtree)/$(obj) --extern alloc --extern kernel \
 		--extern build_error --extern macros \
 		--extern bindings --extern uapi \

base-commit: 4cece764965020c22cff7665b18a012006359095
-- 
2.44.0