Avoid using backtick characters in commit subject

Backticks are disallowed in commit messages because they can be easily
confused with single quotes on some terminals, reducing readability.
Moreover, using backticks to highlight symbols or function names is
unnecessary—plain text or simple single quotes provide sufficient
clarity and emphasis.

Change-Id: I6a1a78546f21fe3a227922ba10ff4d8837066648

Author: jserv

scripts/commit-msg.hook

@@ -265,16 +265,17 @@ validate_commit_message() {
     fi
   done
 
-  # 7. Do no write single worded commits
+  # 7. Ensure the commit subject has more than one word.
   # ------------------------------------------------------------------------------
 
-  COMMIT_SUBJECT_WORDS=(${COMMIT_SUBJECT_TO_PROCESS})
-  test "${#COMMIT_SUBJECT_WORDS[@]}" -gt 1
-  test $? -eq 0 || add_warning 1 "Do no write single worded commits"
+  if [ "$(echo "$COMMIT_SUBJECT_TO_PROCESS" | wc -w)" -le 1 ]; then
+    add_warning 1 "Do not write single-word commits. Provide a descriptive subject"
+  fi
 
-  # 7a. Do not mention C source filenames
-  [[ ${COMMIT_SUBJECT_TO_PROCESS} =~ [_a-zA-Z0-9]+\.[ch]$ ]]
-  test $? -eq 1 || add_warning 1 "Avoid mentioning C source filenames"
+  # 7a. Avoid using C source filenames as the commit subject.
+  if [[ "$COMMIT_SUBJECT_TO_PROCESS" =~ ^[_a-zA-Z0-9]+\.[ch]$ ]]; then
+    add_warning 1 "Avoid mentioning C source filenames in the commit subject"
+  fi
 
   # 8. Use the body to explain what and why vs. how
   # ------------------------------------------------------------------------------
@@ -295,12 +296,12 @@ validate_commit_message() {
   [[ ${COMMIT_SUBJECT_TO_PROCESS} =~ ^[[:blank:]]+ ]]
   test $? -eq 1 || add_warning 1 "Do not start the subject line with whitespace"
 
-  # 10. Avoid single word commit messages in subject
+  # 10. Disallow backticks anywhere in the commit message.
   # ------------------------------------------------------------------------------
 
-  word_count=$(echo "$COMMIT_SUBJECT_TO_PROCESS" | wc -w)
-  test "$word_count" -gt 1
-  test $? -eq 0 || add_warning 1 "Commit subject should contain more than one word. Summarize your changes"
+  if sed '/^[[:space:]]*#/d;/^[[:space:]]*$/d' "$COMMIT_MSG_FILE" | grep -q "\`"; then
+    add_warning 1 "Avoid using backticks in commit messages"
+  fi
 
   # 11. Avoid commit subject that simply states a file update (e.g. "Update console.c")
   # ------------------------------------------------------------------------------