Add test for non-terminal extras that share non-extra rules

test/fixtures/test_grammars/extra_non_terminals_with_shared_rules/corpus.txt

@@ -0,0 +1,23 @@
+=====
+Extras
+=====
+
+;
+%;
+%foo:;
+;
+bar: baz:;
+;
+
+---
+
+(program
+  (statement)
+  (macro_statement (statement))
+  (macro_statement (statement
+    (label_declaration (identifier))))
+  (statement)
+  (statement
+    (label_declaration (identifier))
+    (label_declaration (identifier)))
+  (statement))

test/fixtures/test_grammars/extra_non_terminals_with_shared_rules/grammar.json

@@ -0,0 +1,68 @@
+{
+  "name": "extra_non_terminals_with_shared_rules",
+
+  "extras": [
+    { "type": "PATTERN", "value": "\\s+" },
+    { "type": "SYMBOL", "name": "macro_statement" }
+  ],
+
+  "rules": {
+    "program": {
+      "type": "REPEAT",
+      "content": {
+        "type": "SYMBOL",
+        "name": "statement"
+      }
+    },
+    "statement": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "REPEAT",
+          "content": {
+            "type": "SYMBOL",
+            "name": "label_declaration"
+          }
+        },
+        {
+          "type": "STRING",
+          "value": ";"
+        }
+      ]
+    },
+    "macro_statement": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "%"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "statement"
+        }
+      ]
+    },
+    "label_declaration": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "SYMBOL",
+          "name": "identifier"
+        },
+        {
+          "type": "STRING",
+          "value": ":"
+        }
+      ]
+    },
+    "identifier": {
+      "type": "PATTERN",
+      "value": "[a-zA-Z]+"
+    }
+  },
+  "conflicts": [],
+  "externals": [],
+  "inline": [],
+  "supertypes": []
+}