8331212: Error recovery for broken switch expressions could be improved

Reviewed-by: asotona

Author: lahodaj

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

@@ -470,7 +470,8 @@ public void visitPackageDef(JCPackageDecl tree) {
 
         protected void scanSyntheticBreak(TreeMaker make, JCTree swtch) {
             if (swtch.hasTag(SWITCH_EXPRESSION)) {
-                JCYield brk = make.at(Position.NOPOS).Yield(null);
+                JCYield brk = make.at(Position.NOPOS).Yield(make.Erroneous()
+                                                                .setType(swtch.type));
                 brk.target = swtch;
                 scan(brk);
             } else {

test/langtools/tools/javac/recovery/FlowRecovery.java

@@ -0,0 +1,92 @@
+/*
+ * 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 8331212
+ * @summary Verify error recovery w.r.t. Flow
+ * @library /tools/lib
+ * @enablePreview
+ * @modules jdk.compiler/com.sun.tools.javac.api
+ *          jdk.compiler/com.sun.tools.javac.main
+ *          java.base/jdk.internal.classfile.impl
+ * @build toolbox.ToolBox toolbox.JavacTask
+ * @run main FlowRecovery
+ */
+
+import java.nio.file.Path;
+import java.util.List;
+import java.util.Objects;
+
+import toolbox.JavacTask;
+import toolbox.Task.Expect;
+import toolbox.Task.OutputKind;
+import toolbox.TestRunner;
+import toolbox.ToolBox;
+
+public class FlowRecovery extends TestRunner {
+
+    ToolBox tb;
+
+    public FlowRecovery() {
+        super(System.err);
+        tb = new ToolBox();
+    }
+
+    public static void main(String[] args) throws Exception {
+        FlowRecovery t = new FlowRecovery();
+        t.runTests();
+    }
+
+    @Test //8331212
+    public void testYieldErrors() throws Exception {
+        String code = """
+                      class Test {
+                          public boolean test() {
+                              return switch (0) {
+                                  case 0 -> true;
+                                  default -> {}
+                              };
+                          }
+                      }
+                      """;
+        Path curPath = Path.of(".");
+        List<String> actual = new JavacTask(tb)
+                .options("-XDrawDiagnostics", "-XDdev")
+                .sources(code)
+                .outdir(curPath)
+                .run(Expect.FAIL)
+                .writeAll()
+                .getOutputLines(OutputKind.DIRECT);
+
+        List<String> expected = List.of(
+                "Test.java:5:25: compiler.err.rule.completes.normally",
+                "1 error"
+        );
+
+        if (!Objects.equals(actual, expected)) {
+            error("Expected: " + expected + ", but got: " + actual);
+        }
+    }
+
+}