Build Path Cleanup

build-tool.sh

@@ -2,5 +2,30 @@
 set -eu
 
 cd "$(dirname "$0")"
+output="./tools/sow-toolkit"
+
+tool_sources_are_newer() {
+  if [ ! -x "$output" ]; then
+    return 0
+  fi
+
+  for path in go.mod go.sum cmd internal; do
+    if [ ! -e "$path" ]; then
+      continue
+    fi
+    if [ -n "$(find "$path" -type f -newer "$output" -print -quit)" ]; then
+      return 0
+    fi
+  done
+
+  return 1
+}
+
 mkdir -p tools .cache/go-build
-GOCACHE="${PWD}/.cache/go-build" go build -o ./tools/sow-toolkit ./cmd/nwn-tool
+if ! tool_sources_are_newer; then
+  echo "sow-toolkit is up to date."
+  exit 0
+fi
+
+echo "Building sow-toolkit..."
+GOCACHE="${PWD}/.cache/go-build" go build -o "$output" ./cmd/nwn-tool