From 44f4015f9a649e164b332e6ab1302139191d4a4f Mon Sep 17 00:00:00 2001
From: David Allsopp <david.allsopp@metastack.com>
Date: Wed, 3 Mar 2021 12:24:36 +0000
Subject: [PATCH 07/17] Detect unused Makefile variables in workflow

---
 tools/ci/actions/runner.sh | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/ci/actions/runner.sh b/tools/ci/actions/runner.sh
index ede27f710a..26123b40d1 100755
--- a/tools/ci/actions/runner.sh
+++ b/tools/ci/actions/runner.sh
@@ -21,6 +21,8 @@ PREFIX=~/local
 MAKE="make $MAKE_ARG"
 SHELL=dash
 
+MAKE_WARN="$MAKE --warn-undefined-variables"
+
 export PATH=$PREFIX/bin:$PATH
 
 Configure () {
@@ -60,9 +62,18 @@ EOF
 }
 
 Build () {
-  $MAKE world.opt
+  if [ "$(uname)" = 'Darwin' ]; then
+    script -q build.log $MAKE_WARN
+  else
+    script --return --command "$MAKE_WARN" build.log
+  fi
   echo Ensuring that all names are prefixed in the runtime
   ./tools/check-symbol-names runtime/*.a otherlibs/*/lib*.a
+  if grep -Fq ' warning: undefined variable ' build.log; then
+    echo Undefined Makefile variables detected
+    exit 1
+  fi
+  rm build.log
 }
 
 Test () {
-- 
2.41.0