[PATCH v2 1/1] scripts/rust_is_available: Fix clang version check

["Ethan D. Twardy" <ethan.twardy@gmail.com>]

During out-of-tree builds where the path to the kernel source tree
contains a version string, scripts/rust_is_available.sh incorrectly
identified the version string of libclang to be the version string in
the kernel sources path, resulting in CONFIG_RUST_IS_AVAILABLE
erroneously set to 'n'.

This issue was previously affecting builds on distributions, such as
Gentoo Linux, where the kernel source tree is under version control,
and placed under a path containing the current kernel version string
in /usr/src.

The fix is to take special care to match only the version string
following the string 'clang version' in the output.

To reproduce:

  $ cd ~/build && make -C ~/linux-6.2.0 O=$PWD LLVM=1 rustavailable
  [...]
  *** libclang (used by the Rust bindings generator 'bindgen') is too old.
  ***   Your version:    6.2.0
  ***   Minimum version: 11.0.0
  [...]

Fixes: 78521f3399ab ("scripts: add `rust_is_available.sh`")
Signed-off-by: Ethan D. Twardy <ethan.twardy@gmail.com>

diff --git a/scripts/rust_is_available.sh b/scripts/rust_is_available.sh
index aebbf1913970..e8a1439be9f8 100755
--- a/scripts/rust_is_available.sh
+++ b/scripts/rust_is_available.sh
@@ -102,8 +102,8 @@ fi
 # Check that the `libclang` used by the Rust bindings generator is suitable.
 bindgen_libclang_version=$( \
 	LC_ALL=C "$BINDGEN" $(dirname $0)/rust_is_available_bindgen_libclang.h 2>&1 >/dev/null \
-		| grep -F 'clang version ' \
-		| grep -oE '[0-9]+\.[0-9]+\.[0-9]+' \
+		| grep -oE 'clang version [0-9]+\.[0-9]+\.[0-9]+' \
+		| cut -d' ' -f3 \
 		| head -n 1 \
 )
 bindgen_libclang_min_version=$($min_tool_version llvm)
-- 
2.40.1