ci:upd-tg: check extra warnings W=1

This can detect -Wset-but-not-used-variable warning and others.

Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Change-Id: Id119c54d15e20151c8f933e1e651d9b484d2a709

ci/update-tg-tree.sh

@@ -233,6 +233,14 @@ check_compilation_no_ipv6() {
 	compile_kernel "without IPv6 and with CONFIG_MPTCP" || return 1
 }
 
+check_compilation_extra_warnings() { local src obj
+	for src in net/mptcp/*.c; do
+		obj="${src/%.c/.o}"
+		touch "${src}"
+		KCFLAGS="-Werror" make W=1 "${obj}" || return 1
+	done
+}
+
 # $1: branch
 tg_has_non_mptcp_modified_files() {
 	git diff --name-only "refs/top-bases/${1}..refs/heads/${1}" | \
@@ -278,6 +286,11 @@ validation() { local curr_branch
 			return 1
 		fi
 
+		if ! check_compilation_extra_warnings; then
+			err "Unable to compile mptcp source code with W=1"
+			return 1
+		fi
+
 		if ! check_compilation_no_ipv6; then
 			err "Unable to compile without IPv6"
 			return 1