3 files changed, 86 insertions, 1 deletions

diff --git a/src/delombok/lombok/delombok/PrettyPrinter.java b/src/delombok/lombok/delombok/PrettyPrinter.java
index 6074a01f..2efe05c2 100644
--- a/src/delombok/lombok/delombok/PrettyPrinter.java
+++ b/src/delombok/lombok/delombok/PrettyPrinter.java
@@ -1333,7 +1333,7 @@ public class PrettyPrinter extends JCTree.Visitor {
 			pats = pat == null ? List.<JCTree>nil() : List.of(pat);
 		}
 		
-		if (pats.isEmpty() || pats.get(0).getClass().getName().endsWith("$JCDefaultCaseLabel")) {
+		if (pats.isEmpty() || pats.size() == 1 && pats.head.getClass().getName().endsWith("$JCDefaultCaseLabel")) {
 			aPrint("default");
 		} else {
 			aPrint("case ");
@@ -1424,6 +1424,22 @@ public class PrettyPrinter extends JCTree.Visitor {
 		print((Name) readObject(var, "name", null));
 	}
 	
+	void printDefaultCase(JCTree tree) {
+		print("default");
+	}
+	
+	void printGuardPattern(JCTree tree) {
+		print((JCTree) readObject(tree, "patt", null));
+		print(" && ");
+		print((JCExpression) readObject(tree, "expr", null));
+	}
+	
+	void printParenthesizedPattern(JCTree tree) {
+		print("(");
+		print((JCTree) readObject(tree, "pattern", null));
+		print(")");
+	}
+	
 	@Override public void visitTry(JCTry tree) {
 		aPrint("try ");
 		List<?> resources = readObject(tree, "resources", List.nil());
@@ -1642,6 +1658,12 @@ public class PrettyPrinter extends JCTree.Visitor {
 			printYieldExpression(tree);
 		} else if (className.endsWith("$JCBindingPattern")) { // Introduced as preview in JDK14
 			printBindingPattern(tree);
+		} else if (className.endsWith("$JCDefaultCaseLabel")) { // Introduced in JDK17
+			printDefaultCase(tree);
+		} else if (className.endsWith("$JCGuardPattern")) { // Introduced in JDK17
+			printGuardPattern(tree);
+		} else if (className.endsWith("$JCParenthesizedPattern")) { // Introduced in JDK17
+			printParenthesizedPattern(tree);
 		} else {
 			throw new AssertionError("Unhandled tree type: " + tree.getClass() + ": " + tree);
 		}
diff --git a/test/pretty/resource/after/Switch17.java b/test/pretty/resource/after/Switch17.java
new file mode 100644
index 00000000..038f2cd9
--- /dev/null
+++ b/test/pretty/resource/after/Switch17.java
@@ -0,0 +1,31 @@
+public class Switch17 {
+	String switchPatternMatching(Object o) {
+		return switch (o) {
+			case Integer i -> String.format("int %d", i);
+			case Long l -> String.format("long %d", l);
+			case Double d -> String.format("double %f", d);
+			case String s -> String.format("String %s", s);
+			default -> o.toString();
+		};
+	}
+
+	String switchNull(Object o) {
+		return switch (o) {
+			case null, default -> "?";
+		};
+	}
+
+	String switchGuardPattern(Object o) {
+		return switch (o) {
+			case String s && s.length() > 1 -> s;
+			default -> o.toString();
+		};
+	}
+
+	String switchParenthesizedPattern(Object o) {
+		return switch (o) {
+			case (String s) -> s;
+			default -> o.toString();
+		};
+	}
+}
\ No newline at end of file
diff --git a/test/pretty/resource/before/Switch17.java b/test/pretty/resource/before/Switch17.java
new file mode 100644
index 00000000..17754e82
--- /dev/null
+++ b/test/pretty/resource/before/Switch17.java
@@ -0,0 +1,32 @@
+// version 17:
+public class Switch17 {
+	String switchPatternMatching(Object o) {
+		return switch (o) {
+			case Integer i	-> String.format("int %d", i);
+			case Long l		-> String.format("long %d", l);
+			case Double d	-> String.format("double %f", d);
+			case String s	-> String.format("String %s", s);
+			default			-> o.toString();
+		};
+	}
+
+	String switchNull(Object o) {
+		return switch (o) {
+			case null, default	-> "?";
+		};
+	}
+
+	String switchGuardPattern(Object o) {
+		return switch (o) {
+			case String s && s.length() > 1	-> s;
+			default							-> o.toString();
+		};
+	}
+
+	String switchParenthesizedPattern(Object o) {
+		return switch (o) {
+			case (String s)	-> s;
+			default			-> o.toString();
+		};
+	}
+}