Fixes #670. Left recursive rules imported into a root grammar caused …

…an error. All tests pass in all targets.

tool/src/org/antlr/v4/analysis/LeftRecursiveRuleTransformer.java

@@ -92,7 +92,6 @@ public void translateLeftRecursiveRules() {
 		for (Rule r : rules) {
 			if ( !Grammar.isTokenName(r.name) ) {
 				if ( LeftRecursiveRuleAnalyzer.hasImmediateRecursiveRuleRefs(r.ast, r.name) ) {
-					g.originalTokenStream = g.tokenStream;
 					boolean fitsPattern = translateLeftRecursiveRule(ast, (LeftRecursiveRule)r, language);
 					if ( fitsPattern ) leftRecursiveRuleNames.add(r.name);
 				}
@@ -131,11 +130,15 @@ public boolean translateLeftRecursiveRule(GrammarRootAST ast,
 		}
 		if ( !isLeftRec ) return false;
 
-		// replace old rule's AST
+		// replace old rule's AST; first create text of altered rule
 		GrammarAST RULES = (GrammarAST)ast.getFirstChildWithType(ANTLRParser.RULES);
 		String newRuleText = leftRecursiveRuleWalker.getArtificialOpPrecRule();
 //		System.out.println("created: "+newRuleText);
-		RuleAST t = parseArtificialRule(g, newRuleText);
+		// now parse within the context of the grammar that originally created
+		// the AST we are transforming. This could be an imported grammar so
+		// we cannot just reference this.g because the role might come from
+		// the imported grammar and not the root grammar (this.g)
+		RuleAST t = parseArtificialRule(prevRuleAST.g, newRuleText);
 
 		// reuse the name token from the original AST since it refers to the proper source location in the original grammar
 		((GrammarAST)t.getChild(0)).token = ((GrammarAST)prevRuleAST.getChild(0)).getToken();

tool/src/org/antlr/v4/tool/Grammar.java

@@ -155,10 +155,19 @@ public class Grammar implements AttributeResolver {
 
 	public String name;
     public GrammarRootAST ast;
-	/** Track stream used to create this grammar */
+
+	/** Track token stream used to create this grammar */
 	@NotNull
 	public final org.antlr.runtime.TokenStream tokenStream;
-	/** If we transform grammar, track original unaltered token stream */
+
+	/** If we transform grammar, track original unaltered token stream.
+	 *  This is set to the same value as tokenStream when tokenStream is
+	 *  initially set.
+	 *
+	 *  If this field differs from tokenStream, then we have transformed
+	 *  the grammar.
+	 */
+	@NotNull
 	public org.antlr.runtime.TokenStream originalTokenStream;
 
     public String text; // testing only
@@ -288,6 +297,7 @@ public Grammar(Tool tool, @NotNull GrammarRootAST ast) {
         this.ast = ast;
         this.name = (ast.getChild(0)).getText();
 		this.tokenStream = ast.tokenStream;
+		this.originalTokenStream = this.tokenStream;
 
 		initTokenSymbolTables();
     }
@@ -343,6 +353,7 @@ public Grammar(String fileName, String grammarText, Grammar tokenVocabSource, @N
 		}
 
 		this.tokenStream = ast.tokenStream;
+		this.originalTokenStream = this.tokenStream;
 
 		// ensure each node has pointer to surrounding grammar
 		final Grammar thiz = this;