[PATCH 5/6] kbuild: rust_is_available: fix confusion when a version appears in the path

[Miguel Ojeda]

`bindgen`'s output for `libclang`'s version check contains paths, which
in turn may contain strings that look like version numbers [1]:

    .../6.1.0-dev/.../rust_is_available_bindgen_libclang.h:2:9: warning: clang version 11.1.0  [-W#pragma-messages], err: false

which the script will pick up as the version instead of the latter.

It is also the case that versions may appear after the actual version
(e.g. distribution's version text), which was the reason behind `head` [2]:

    .../rust-is-available-bindgen-libclang.h:2:9: warning: clang version 13.0.0 (Fedora 13.0.0-3.fc35) [-W#pragma-messages], err: false

Thus instead ask for a match after the `clang version` string.

Reported-by: Jordan (@jordanisaacs)
Link: https://github.com/Rust-for-Linux/linux/issues/942 [1]
Link: https://github.com/Rust-for-Linux/linux/pull/789 [2]
Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx>
---
 scripts/rust_is_available.sh | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/scripts/rust_is_available.sh b/scripts/rust_is_available.sh
index 0c082a248f15..a86659410e48 100755
--- a/scripts/rust_is_available.sh
+++ b/scripts/rust_is_available.sh
@@ -141,9 +141,7 @@ fi
 # of the `libclang` found by the Rust bindings generator is suitable.
 bindgen_libclang_version=$( \
 	echo "$bindgen_libclang_output" \
-		| grep -F 'clang version ' \
-		| grep -oE '[0-9]+\.[0-9]+\.[0-9]+' \
-		| head -n 1 \
+		| sed -nE 's:.*clang version ([0-9]+\.[0-9]+\.[0-9]+).*:\1:p'
 )
 bindgen_libclang_min_version=$($min_tool_version llvm)
 bindgen_libclang_cversion=$(get_canonical_version $bindgen_libclang_version)
-- 
2.39.0