Warn about unused rules (currently breaks the build!)

cmd/vic-machine/inspect/.godeps_rules

@@ -10,3 +10,4 @@
 ^cmd/vic-machine/converter/*
 ^cmd/vic-machine/create/*
 
+^UNUSED

infra/scripts/go-deps-enforcement.sh

@@ -29,6 +29,17 @@ find-packages () {
     find "${@}" -type f -name '*.go' -exec dirname {} \; | sort --unique
 }
 
+# Returns a list of all directories containing a rule file
+# Arguments
+# *: directories to search under
+#
+# Returns:
+# directories with rule files
+find-rule-dirs () {
+    find "${@}" -type f -name "$RULES_FILE" -exec dirname {} \; | sort --unique
+}
+
+
 # Returns the path to the "nearest" rule file for a given package
 # Arguments
 # 1: package path
@@ -102,7 +113,42 @@ for package in $(find-packages "${ENFORCE[@]}"); do
         echo "${invalid//^/  /}"
         echo "See $rules for details."
         echo ""
-        rc=1
+        rc=$(( rc | 1 ))
+    fi
+done
+
+export VIC_CACHE_DEPS=true #TODO: verify this doesn't leak!
+# for each rule file
+for directory in $(find-rule-dirs "${ENFORCE[@]}"); do
+    deps=""
+    # for each package under that rule file
+    for package in $(find-packages "$directory"); do
+        # find-rule for the package
+        rules="$(find-rule "$package")"
+        # if not the rule file from the outer loop (i.e, the directory is covered by a more specific file)s, continue
+        if [ "$directory" != "$(dirname "$rules")" ]; then
+            continue
+        fi
+        # accumulate deps
+        deps+="$(get-deps "$package")"
+    done
+
+    # use grep to make sure each pattern matches at least one dep
+    unused=()
+    for rule in $(get-rules "$rules"); do
+        matches=$(echo "$deps" | grep -c -e "$rule" || true)
+
+        # if not, error with the rule file and unmatched rule
+        if [ "$matches" = "0" ]; then
+            unused+=("$rule")
+        fi
+    done
+
+    if [ ${#unused[@]} -ne 0 ]; then
+        echo "Unused rules in $rules:"
+        printf '  %s\n' "${unused[@]}"
+        echo ""
+        rc=$(( rc | 2 ))
     fi
 done