Compiler has trouble parsing multipattern case label expressions.

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

@@ -5176,6 +5176,7 @@ public VanguardParser(ProblemReporter reporter) {
 
 	// Canonical LALR pushdown automaton identical to Parser.parse() minus side effects of any kind, returns the rule reduced.
 	protected boolean parse(Goal goal) {
+		int parenthesized = 0;
 		this.currentGoal = goal;
 		try {
 			int act = START_STATE;
@@ -5201,6 +5202,10 @@ protected boolean parse(Goal goal) {
 					this.unstackedAct = act;
 					try {
 					this.currentToken = this.scanner.getNextToken();
+					if (this.currentToken == TokenNameLPAREN)
+						parenthesized++;
+					else if (this.currentToken == TokenNameRPAREN)
+						parenthesized --;
 					} finally {
 						this.unstackedAct = ERROR_ACTION;
 					}
@@ -5210,6 +5215,10 @@ protected boolean parse(Goal goal) {
 				    	this.unstackedAct = act;
 						try {
 				    	this.currentToken = this.scanner.getNextToken();
+				    	if (this.currentToken == TokenNameLPAREN)
+				    		parenthesized++;
+						else if (this.currentToken == TokenNameRPAREN)
+							parenthesized --;
 						} finally {
 							this.unstackedAct = ERROR_ACTION;
 						}
@@ -5220,6 +5229,15 @@ protected boolean parse(Goal goal) {
 
 				// ProcessNonTerminals :
 				do { /* reduce */
+					// mimic the unfortunate side effect introduced by org.eclipse.jdt.internal.compiler.parser.Parser.consumeCaseLabelElement(CaseLabelKind)
+					if (parenthesized == 0 && this.currentToken == TerminalTokens.TokenNameCOMMA && this.scanner.caseStartPosition < this.scanner.startPosition) {
+						for (int patternRule : Goal.PatternRules) {
+							if (act == patternRule) {
+								this.scanner.multiCaseLabelComma = true;
+								break;
+							}
+						}
+					}
 					if (goal.hasBeenReached(act, this.currentToken))
 						return SUCCESS;
 					if (this.currentToken == TokenNameIdentifier) {

org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/SwitchPatternTest21.java

@@ -836,4 +836,126 @@ public static void main(String... args) {
 						""", },
 				"success");
 	}
+
+	// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/2070
+	// [Switch] Compiler is unable to parse a particular multicase construct
+	public void testIssue2070() {
+		runConformTest(
+				new String[] {
+						"X.java",
+						"""
+						public class X {
+						    public boolean foo(Object o) {
+						    	return switch (o) {
+						    	case Integer _, Integer[] _ -> true;
+						    		default -> false;
+						    	};
+						    }
+						    public static void main(String argv[]) {
+						    	System.out.println(new X().foo(new Object()));
+						    }
+						}
+						"""
+				},
+			"false");
+	}
+
+	// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/2956
+	// Unnamed patterns inside of multi case patterns fail to parse
+	public void testIssue2956() {
+		runConformTest(
+				new String[] {
+						"Main.java",
+						"""
+						public class Main {
+						    public sealed interface MyType {
+						        record A() implements MyType {
+						        }
+
+						        record B(int value) implements MyType {
+						        }
+
+						        record C() implements MyType {
+						        }
+						    }
+
+						    public static void main(String[] args) {
+						        MyType myType = new MyType.A();
+						        switch (myType) {
+						            case MyType.A(), MyType.B(_) -> { System.out.println("A or B");}
+						            case MyType.C() -> {}
+						        }
+						    }
+						}
+						"""
+				},
+			"A or B");
+	}
+
+
+	// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/2956
+	// Unnamed patterns inside of multi case patterns fail to parse
+	public void testIssue2956_2() {
+		runConformTest(
+				new String[] {
+						"Main.java",
+						"""
+						public class Main {
+						    public sealed interface MyType {
+						        record A() implements MyType {
+						        }
+
+						        record B(int value) implements MyType {
+						        }
+
+						        record C() implements MyType {
+						        }
+						    }
+
+						    public static void main(String[] args) {
+						        MyType myType = new MyType.A();
+						        switch (myType) {
+						            case MyType.A()  ->  { System.out.println("A");}
+						            case MyType.B(_) ->  { System.out.println("B");}
+						            case MyType.C()  ->  { System.out.println("C");}
+						        }
+						    }
+						}
+						"""
+				},
+			"A");
+	}
+
+
+	// https://github.com/eclipse-jdt/eclipse.jdt.core/issues/2956
+	// Unnamed patterns inside of multi case patterns fail to parse
+	public void testIssue2956_3() {
+		runConformTest(
+				new String[] {
+						"Main.java",
+						"""
+						public class Main {
+						    public sealed interface MyType {
+						        record A() implements MyType {
+						        }
+
+						        record B(int value) implements MyType {
+						        }
+
+						        record C() implements MyType {
+						        }
+						    }
+
+						    public static void main(String[] args) {
+						        MyType myType = new MyType.A();
+						        switch (myType) {
+						            case MyType.B(_), MyType.A()  -> { System.out.println("A or B");}
+						            case MyType.C() -> {}
+						        }
+						    }
+						}
+						"""
+				},
+			"A or B");
+	}
 }