Merge pull request #514 from sharwell/fix-500

Add compile error 159: RESERVED_RULE_NAME (fixes #500)

tool/src/org/antlr/v4/semantics/SymbolChecks.java

@@ -67,6 +67,11 @@ public class SymbolChecks {
 
 	public ErrorManager errMgr;
 
+	protected final Set<String> reservedNames = new HashSet<String>();
+	{
+		reservedNames.add("EOF");
+	}
+
     public SymbolChecks(Grammar g, SymbolCollector collector) {
         this.g = g;
         this.collector = collector;
@@ -94,6 +99,7 @@ public class SymbolChecks {
 		if ( g.rules!=null ) {
 			for (Rule r : g.rules.values()) nameToRuleMap.put(r.name, r);
 		}
+		checkReservedNames(g.rules.values());
 		checkActionRedefinitions(collector.namedActions);
 		checkForTokenConflicts(collector.tokenIDRefs);  // sets tokenIDs
 		checkForLabelConflicts(g.rules.values());
@@ -257,6 +263,14 @@ public class SymbolChecks {
 		}
 	}
 
+	protected void checkReservedNames(@NotNull Collection<Rule> rules) {
+		for (Rule rule : rules) {
+			if (reservedNames.contains(rule.name)) {
+				errMgr.grammarError(ErrorType.RESERVED_RULE_NAME, g.fileName, ((GrammarAST)rule.ast.getChild(0)).getToken(), rule.name);
+			}
+		}
+	}
+
 	// CAN ONLY CALL THE TWO NEXT METHODS AFTER GRAMMAR HAS RULE DEFS (see semanticpipeline)
 
 	public void checkRuleArgs(Grammar g, List<GrammarAST> rulerefs) {

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

@@ -883,6 +883,23 @@ public enum ErrorType {
 	 * @since 4.2.1
 	 */
 	FRAGMENT_ACTION_IGNORED(158, "fragment rule '<arg>' contains an action or command which can never be executed", ErrorSeverity.WARNING),
+	/**
+	 * Compiler Error 159.
+	 *
+	 * <p>cannot declare a rule with reserved name '<em>rule</em>'</p>
+	 *
+	 * <p>A rule was declared with a reserved name.</p>
+	 *
+	 * <p>The following rule produces this error.</p>
+	 *
+	 * <pre>
+	 * EOF : ' '   // error 159 (EOF is a reserved name)
+	 *     ;
+	 * </pre>
+	 *
+	 * @since 4.2.1
+	 */
+	RESERVED_RULE_NAME(159, "cannot declare a rule with reserved name '<arg>'", ErrorSeverity.ERROR),
 
 	/*
 	 * Backward incompatibility errors

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

@@ -706,6 +706,11 @@ public class Grammar implements AttributeResolver {
 	}
 
 	public void setTokenForType(int ttype, String text) {
+		if (ttype == Token.EOF) {
+			// ignore EOF, it will be reported as an error separately
+			return;
+		}
+
 		if ( ttype>=typeToTokenList.size() ) {
 			Utils.setSize(typeToTokenList, ttype+1);
 		}

tool/test/org/antlr/v4/test/TestToolSyntaxErrors.java

@@ -502,4 +502,25 @@ public class TestToolSyntaxErrors extends BaseTest {
 
 		super.testErrors(pair, true);
 	}
+
+	/**
+	 * This is a regression test for antlr/antlr4#500 "Array Index Out Of
+	 * Bounds".
+	 * https://github.com/antlr/antlr4/issues/500
+	 */
+	@Test public void testTokenNamedEOF() {
+		String grammar =
+			"lexer grammar A;\n" +
+			"WS : ' ';\n" +
+			" EOF : 'a';\n";
+		String expected =
+			"error(" + ErrorType.RESERVED_RULE_NAME.code + "): A.g4:3:1: cannot declare a rule with reserved name 'EOF'\n";
+
+		String[] pair = new String[] {
+			grammar,
+			expected
+		};
+
+		super.testErrors(pair, true);
+	}
 }