From 773f647afa57ab791d13cecf5ce5af6bde98ffde Mon Sep 17 00:00:00 2001
From: Stephan Schroevers <stephan.schroevers@teampicnic.com>
Date: Sat, 31 Dec 2022 14:53:59 +0100
Subject: [PATCH] StatementSwitchToExpressionSwitch: handle empty statement
 blocks

Fixes #3638.
---
 .../StatementSwitchToExpressionSwitch.java      |  2 +-
 .../StatementSwitchToExpressionSwitchTest.java  | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/StatementSwitchToExpressionSwitch.java b/core/src/main/java/com/google/errorprone/bugpatterns/StatementSwitchToExpressionSwitch.java
index b885de8b298..8d53a085ae7 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/StatementSwitchToExpressionSwitch.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/StatementSwitchToExpressionSwitch.java
@@ -122,7 +122,7 @@ private static AnalysisResult analyzeSwitchTree(SwitchTree switchTree) {
 
       List<? extends StatementTree> statements = caseTree.getStatements();
       CaseFallThru caseFallThru = CaseFallThru.MAYBE_FALLS_THRU;
-      if (statements.isEmpty()) {
+      if (statements == null || statements.isEmpty()) {
         // If the code for this case is just an empty block, then it must fall thru
         caseFallThru = CaseFallThru.DEFINITELY_DOES_FALL_THRU;
         // Can group with the next case (unless this is the last case)
diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/StatementSwitchToExpressionSwitchTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/StatementSwitchToExpressionSwitchTest.java
index 535fa765ee9..623ee82f4b7 100644
--- a/core/src/test/java/com/google/errorprone/bugpatterns/StatementSwitchToExpressionSwitchTest.java
+++ b/core/src/test/java/com/google/errorprone/bugpatterns/StatementSwitchToExpressionSwitchTest.java
@@ -1016,6 +1016,23 @@ public void singleCaseConvertible_error() {
         .doTest();
   }
 
+  @Test
+  public void emptySwitchCases_noMatch() {
+    assumeTrue(RuntimeVersion.isAtLeast14());
+    helper
+        .addSourceLines(
+            "Test.java",
+            "class Test {",
+            "  void foo(int value) { ",
+            "    switch (value) {",
+            "      case 0 -> {}",
+            "      default -> {}",
+            "    }",
+            "  }",
+            "}")
+        .doTest();
+  }
+
   @Test
   public void dynamicWithThrowableDuringInitializationFromMethod_noMatch() {
     assumeTrue(RuntimeVersion.isAtLeast14());