From 4dd1c78e67086b1232282325d5aa9b6288ab08fb Mon Sep 17 00:00:00 2001
From: Liam Miller-Cushon <cushon@google.com>
Date: Fri, 15 Sep 2023 11:42:17 -0700
Subject: [PATCH] Don't require `// fall out ` comments on expression switches

https://github.com/google/error-prone/issues/2709

PiperOrigin-RevId: 565736512
---
 .../bugpatterns/MissingDefault.java           |  2 +-
 .../bugpatterns/MissingDefaultTest.java       | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/MissingDefault.java b/core/src/main/java/com/google/errorprone/bugpatterns/MissingDefault.java
index e77472ff2200..d3129dd9f19d 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/MissingDefault.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/MissingDefault.java
@@ -75,7 +75,7 @@ public Description matchSwitch(SwitchTree tree, VisitorState state) {
     }
     CaseTree defaultCase = maybeDefault.get();
     List<? extends StatementTree> statements = defaultCase.getStatements();
-    if (statements != null && !statements.isEmpty()) {
+    if (statements == null || !statements.isEmpty()) {
       return NO_MATCH;
     }
     // If `default` case is empty, and last in switch, add `// fall out` comment
diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/MissingDefaultTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/MissingDefaultTest.java
index 05f77cab6c87..9799b78fe4fc 100644
--- a/core/src/test/java/com/google/errorprone/bugpatterns/MissingDefaultTest.java
+++ b/core/src/test/java/com/google/errorprone/bugpatterns/MissingDefaultTest.java
@@ -263,4 +263,23 @@ public void arrowSwitchNegative() {
             "}")
         .doTest();
   }
+
+  @Test
+  public void arrowComment() {
+    assumeTrue(RuntimeVersion.isAtLeast14());
+    compilationHelper
+        .addSourceLines(
+            "Test.java",
+            "class Test {",
+            "  void f() {}",
+            "  void m(int i) {",
+            "    switch (i) {",
+            "      case 0 -> f();",
+            "      case 1 -> f();",
+            "      default -> f();",
+            "    }",
+            "  }",
+            "}")
+        .doTest();
+  }
 }