[gentoo-dev] [PATCH] llvm-utils.eclass: Fix llvm_prepend_path to avoid duplicates

["Michał Górny" <mgorny@gentoo.org>]

Fix llvm_prepend_path() not to append the new path multiple times,
if the original PATH variable contained multiple LLVM directories.

Thanks to Alexander Miller who spotted it in:
https://github.com/gentoo/gentoo/pull/35196#discussion_r1480330001

Signed-off-by: Michał Górny <mgorny@gentoo.org>
---
 eclass/llvm-utils.eclass   | 10 ++++++----
 eclass/tests/llvm-utils.sh | 12 ++++++++++++
 2 files changed, 18 insertions(+), 4 deletions(-)

Changed in v2: simplified the logic, courtesy of Alexander Miller,
and added more test cases.

diff --git a/eclass/llvm-utils.eclass b/eclass/llvm-utils.eclass
index f308667e3dc2..532e609679b8 100644
--- a/eclass/llvm-utils.eclass
+++ b/eclass/llvm-utils.eclass
@@ -129,16 +129,18 @@ llvm_prepend_path() {
 	local new_path=()
 	local x added=
 
-	# prepend new path in front of the first LLVM version found
 	for x in "${split_path[@]}"; do
 		if [[ ${x} == */usr/lib/llvm/*/bin ]]; then
-			if [[ ${x} != ${llvm_path} ]]; then
+			# prepend new path in front of the first LLVM version found
+			if [[ ! ${added} ]]; then
 				new_path+=( "${llvm_path}" )
-			elif [[ ${added} && ${x} == ${llvm_path} ]]; then
+				added=1
+			fi
+			# remove duplicate copies of the same path
+			if [[ ${x} == ${llvm_path} ]]; then
 				# deduplicate
 				continue
 			fi
-			added=1
 		fi
 		new_path+=( "${x}" )
 	done
diff --git a/eclass/tests/llvm-utils.sh b/eclass/tests/llvm-utils.sh
index 5a46b25b7ad6..6fe3da3eda13 100755
--- a/eclass/tests/llvm-utils.sh
+++ b/eclass/tests/llvm-utils.sh
@@ -98,9 +98,21 @@ ESYSROOT=
 test_prepend_path 17 /usr/bin /usr/bin:/usr/lib/llvm/17/bin
 test_prepend_path 17 /usr/lib/llvm/17/bin:/usr/bin /usr/lib/llvm/17/bin:/usr/bin
 test_prepend_path 17 /usr/bin:/usr/lib/llvm/17/bin /usr/bin:/usr/lib/llvm/17/bin
+test_prepend_path 17 /usr/lib/llvm/17/bin:/usr/bin:/usr/lib/llvm/17/bin \
+	/usr/lib/llvm/17/bin:/usr/bin
+test_prepend_path 17 /usr/lib/llvm/17/bin:/usr/lib/llvm/17/bin:/usr/bin \
+	/usr/lib/llvm/17/bin:/usr/bin
+test_prepend_path 17 /usr/bin:/usr/lib/llvm/17/bin:/usr/lib/llvm/17/bin \
+	/usr/bin:/usr/lib/llvm/17/bin
 test_prepend_path 18 /usr/lib/llvm/17/bin:/usr/bin \
 	/usr/lib/llvm/18/bin:/usr/lib/llvm/17/bin:/usr/bin
 test_prepend_path 18 /usr/bin:/usr/lib/llvm/17/bin \
 	/usr/bin:/usr/lib/llvm/18/bin:/usr/lib/llvm/17/bin
+test_prepend_path 18 /usr/lib/llvm/17/bin:/usr/lib/llvm/16/bin:/usr/bin \
+	/usr/lib/llvm/18/bin:/usr/lib/llvm/17/bin:/usr/lib/llvm/16/bin:/usr/bin
+test_prepend_path 18 /usr/bin:/usr/lib/llvm/17/bin:/usr/lib/llvm/16/bin \
+	/usr/bin:/usr/lib/llvm/18/bin:/usr/lib/llvm/17/bin:/usr/lib/llvm/16/bin
+test_prepend_path 18 /usr/lib/llvm/17/bin:/usr/bin:/usr/lib/llvm/16/bin \
+	/usr/lib/llvm/18/bin:/usr/lib/llvm/17/bin:/usr/bin:/usr/lib/llvm/16/bin
 
 texit
-- 
2.43.0