8323502: javac crash with wrongly typed method block in Flow

Co-authored-by: Jan Lahoda <jlahoda@openjdk.org>
Reviewed-by: jlahoda

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java

@@ -1610,14 +1610,16 @@ public void visitSwitch(JCSwitch tree) {
     }
 
     public void visitSwitchExpression(JCSwitchExpression tree) {
+        boolean wrongContext = false;
+
         tree.polyKind = (pt().hasTag(NONE) && pt() != Type.recoveryType && pt() != Infer.anyPoly) ?
                 PolyKind.STANDALONE : PolyKind.POLY;
 
         if (tree.polyKind == PolyKind.POLY && resultInfo.pt.hasTag(VOID)) {
             //this means we are returning a poly conditional from void-compatible lambda expression
             resultInfo.checkContext.report(tree, diags.fragment(Fragments.SwitchExpressionTargetCantBeVoid));
-            result = tree.type = types.createErrorType(resultInfo.pt);
-            return;
+            resultInfo = recoveryInfo;
+            wrongContext = true;
         }
 
         ResultInfo condInfo = tree.polyKind == PolyKind.STANDALONE ?
@@ -1655,7 +1657,7 @@ public void visitYield(JCYield brk) {
 
         Type owntype = (tree.polyKind == PolyKind.STANDALONE) ? condType(caseTypePositions.toList(), caseTypes.toList()) : pt();
 
-        result = tree.type = check(tree, owntype, KindSelector.VAL, resultInfo);
+        result = tree.type = wrongContext? types.createErrorType(pt()) : check(tree, owntype, KindSelector.VAL, resultInfo);
     }
     //where:
         CheckContext switchExpressionContext(CheckContext checkContext) {

test/langtools/tools/javac/T8323502.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+/*
+ * @test
+ * @bug 8323502
+ * @summary javac crash with wrongly typed method block in Flow
+ * @compile/fail/ref=T8323502.out -XDrawDiagnostics --should-stop=at=FLOW -XDdev T8323502.java
+ */
+public class T8323502 {
+    public void m(Object o) {
+        return switch(o) {
+            default -> System.out.println("boom");
+        };
+    }
+}

test/langtools/tools/javac/T8323502.out

@@ -0,0 +1,2 @@
+T8323502.java:31:16: compiler.err.prob.found.req: (compiler.misc.unexpected.ret.val)
+1 error