8272776: NullPointerException not reported

Backport-of: 93eec9a103de7f4d9a87eac5b295c9a50702ee94

Author: Alexey Pavlyutkin

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

@@ -341,9 +341,8 @@ private void handleSwitch(JCTree tree,
             JCCase lastCase = cases.last();
 
             if (hasTotalPattern && !hasNullCase) {
-                JCCase last = lastCase;
-                if (last.labels.stream().noneMatch(l -> l.hasTag(Tag.DEFAULTCASELABEL))) {
-                    last.labels = last.labels.prepend(makeLit(syms.botType, null));
+                if (cases.stream().flatMap(c -> c.labels.stream()).noneMatch(l -> l.hasTag(Tag.DEFAULTCASELABEL))) {
+                    lastCase.labels = lastCase.labels.prepend(makeLit(syms.botType, null));
                     hasNullCase = true;
                 }
             }

test/langtools/tools/javac/patterns/NullSwitch.java

@@ -1,6 +1,6 @@
 /*
  * @test /nodynamiccopyright/
- * @bug 8262891
+ * @bug 8262891 8272776
  * @summary Check null handling for non-pattern switches.
  * @compile --enable-preview -source ${jdk.version} NullSwitch.java
  * @run main/othervm --enable-preview NullSwitch
@@ -57,6 +57,9 @@ void switchTest() {
         assertEquals(0, matchingSwitch12(""));
         assertEquals(2, matchingSwitch12(null));
         assertEquals(1, matchingSwitch12(0.0));
+        assertEquals(0, matchingSwitch13(""));
+        assertEquals(1, matchingSwitch13(0.0));
+        assertEquals(2, matchingSwitch13(null));
     }
 
     private int matchingSwitch1(Object obj) {
@@ -159,6 +162,17 @@ private int matchingSwitch12(Object obj) {
         }
     }
 
+    private int matchingSwitch13(Object obj) {
+        try {
+            switch (obj) {
+                default: return 1;
+                case String s: return 0;
+            }
+        } catch (NullPointerException ex) {
+            return 2;
+        }
+    }
+
     static void assertEquals(int expected, int actual) {
         if (expected != actual) {
             throw new AssertionError("Expected: " + expected + ", actual: " + actual);