more tests

[git-p4: depot-paths = "//depot/code/antlr4/main/": change = 6808]

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

@@ -84,10 +84,7 @@ public class NFAConfig {
 
 	/** An NFA configuration is equal to another if both have
      *  the same state, they predict the same alternative, and
-     *  syntactic/semantic contexts are the same.  I don't think
-     *  the state|alt|ctx could be the same and have two different
-     *  semantic contexts, but might as well define equals to be
-     *  everything.
+     *  syntactic/semantic contexts are the same.
      */
     public boolean equals(Object o) {
 		if ( o==null ) return false;

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

@@ -62,6 +62,25 @@ public class TestPredicatedDFAConstruction extends BaseTest {
 		System.err.println(msgs);
 	}
 
+	@Test
+	public void testSemanticContextPreventsEarlyTerminationOfClosure() throws Exception {
+		String g =
+			"parser grammar T;\n" +
+			"a : loop SEMI | ID SEMI\n" +
+			"  ;\n" +
+			"loop\n" +
+			"    : {while}? ID\n" +
+			"    | {do}? ID\n" +
+			"    | {for}? ID\n" +
+			"    ;";
+		String expecting =
+			"s0-ID->s1\n" +
+			"s1-SEMI->s2\n" +
+			"s2-({while}?||{for}?||{do}?)->:s3=>1\n" +
+			"s2-true->:s4=>2\n";
+		checkRuleDFA(g, "a", expecting);
+	}
+
 	@Test public void _template() throws Exception {
 		String g =
 			"";