Experiment to run a subset

org.eclipse.jdt.core.compiler.batch/grammar/java.g

@@ -1514,6 +1514,8 @@ SwitchLabels ::= SwitchLabel ':'
 /.$putCase consumeSwitchLabels(false, false) ; $break ./
 SwitchLabels ::= SwitchLabels SwitchLabel ':'
 /.$putCase consumeSwitchLabels(true, false) ; $break ./
+SwitchLabels ::= SwitchLabels SwitchLabel CaseArrow  -- to ease yield disambiguation, will be rejected.
+/.$putCase consumeSwitchLabels(true, true) ; $break ./
 /:$readableName SwitchLabel:/
 
 PostCaseArrow ::= $empty

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/parser/ParserBasicInformation.java

@@ -25,17 +25,17 @@ public interface ParserBasicInformation {
 					NUM_STATES = 1239,
 
 					NT_OFFSET = 138,
-					SCOPE_UBOUND = 320,
-					SCOPE_SIZE = 321,
-					LA_STATE_OFFSET = 18346,
+					SCOPE_UBOUND = 321,
+					SCOPE_SIZE = 322,
+					LA_STATE_OFFSET = 18347,
 					MAX_LA = 1,
-					NUM_RULES = 940,
+					NUM_RULES = 941,
 					NUM_TERMINALS = 138,
 					NUM_NON_TERMINALS = 432,
 					NUM_SYMBOLS = 570,
-					START_STATE = 1137,
+					START_STATE = 1138,
 					EOFT_SYMBOL = 39,
 					EOLT_SYMBOL = 39,
-					ACCEPT_ACTION = 18345,
-					ERROR_ACTION = 18346;
+					ACCEPT_ACTION = 18346,
+					ERROR_ACTION = 18347;
 }

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/parser/Scanner.java

@@ -3306,11 +3306,14 @@ final void addTokenToLookBack(int newToken) {
 		case TokenNameCOLON:
 			if (this.lookBack[1] == TokenNamedefault)
 				this.atClassicSwitchLabel = true;
-			if (this.scanningSwitchLabel)
+			if (this.scanningSwitchLabel) {
+				System.out.println("Checking if at end of classic switch label"); //$NON-NLS-1$
 				if (this.activeParser == null || this.activeParser.automatonWillShift(TokenNameCaseArrow)) {
 					this.scanningSwitchLabel = false;
 					this.atClassicSwitchLabel = true;
 				}
+				System.out.println("Done Checking if at end of classic switch label"); //$NON-NLS-1$
+			}
 			break;
 	}
 	this.lookBack[0] = this.lookBack[1];

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/parser/TerminalTokens.java

@@ -101,7 +101,7 @@ static int getRestrictedKeyword(String text) {
 							TokenNameimport = 111,
 							TokenNameinstanceof = 17,
 							TokenNameint = 112,
-							TokenNameinterface = 72,
+							TokenNameinterface = 73,
 							TokenNamelong = 113,
 							TokenNamenative = 46,
 							TokenNamenew = 40,
@@ -197,10 +197,10 @@ static int getRestrictedKeyword(String text) {
 							TokenNameBeginLambda = 64,
 							TokenNameBeginIntersectionCast = 69,
 							TokenNameBeginTypeArguments = 89,
-							TokenNameElidedSemicolonAndRightBrace = 73,
+							TokenNameElidedSemicolonAndRightBrace = 74,
 							TokenNameAT308 = 27,
 							TokenNameAT308DOTDOTDOT = 129,
-							TokenNameCaseArrow = 74,
+							TokenNameCaseArrow = 72,
 							TokenNameRestrictedIdentifierYield = 90,
 							TokenNameRestrictedIdentifierrecord = 76,
 							TokenNameRestrictedIdentifiersealed = 43,