From 1c997abe7dd33c725e8b652f683ac08ca7c1440f Mon Sep 17 00:00:00 2001
From: Sumit Bhagwani <bhagwani@google.com>
Date: Fri, 3 Dec 2021 00:57:40 -0800
Subject: [PATCH] Don't crash for CaseKind.RULE in SwitchDefault

Similar to http://https://github.com/google/error-prone/commit/e5d52dddb7ce3861e4929a640b70e566370111f3

Fixes #2705

PiperOrigin-RevId: 413868350
---
 .../errorprone/bugpatterns/SwitchDefault.java |  9 ++-
 .../bugpatterns/SwitchDefaultTest.java        | 67 +++++++++++++++++++
 2 files changed, 74 insertions(+), 2 deletions(-)

diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/SwitchDefault.java b/core/src/main/java/com/google/errorprone/bugpatterns/SwitchDefault.java
index 4a27a64813c..75c1d7e4375 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/SwitchDefault.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/SwitchDefault.java
@@ -33,6 +33,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Optional;
+import javax.annotation.Nullable;
 
 /** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
 @BugPattern(
@@ -56,13 +57,13 @@ public Description matchSwitch(SwitchTree tree, VisitorState state) {
       CaseTree caseTree = it.next();
       defaultStatementGroup.add(caseTree);
       if (caseTree.getExpression() == null) {
-        while (it.hasNext() && caseTree.getStatements().isEmpty()) {
+        while (it.hasNext() && isNullOrEmpty(caseTree.getStatements())) {
           caseTree = it.next();
           defaultStatementGroup.add(caseTree);
         }
         break;
       }
-      if (!caseTree.getStatements().isEmpty()) {
+      if (!isNullOrEmpty(caseTree.getStatements())) {
         defaultStatementGroup.clear();
       }
     }
@@ -119,4 +120,8 @@ public Description matchSwitch(SwitchTree tree, VisitorState state) {
     }
     return description.build();
   }
+
+  private static <T> boolean isNullOrEmpty(@Nullable List<T> elementList) {
+    return elementList == null || elementList.isEmpty();
+  }
 }
diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/SwitchDefaultTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/SwitchDefaultTest.java
index 244245f53d0..7c11cf4d03b 100644
--- a/core/src/test/java/com/google/errorprone/bugpatterns/SwitchDefaultTest.java
+++ b/core/src/test/java/com/google/errorprone/bugpatterns/SwitchDefaultTest.java
@@ -16,7 +16,11 @@
 
 package com.google.errorprone.bugpatterns;
 
+import static org.junit.Assume.assumeTrue;
+
 import com.google.errorprone.BugCheckerRefactoringTestHelper;
+import com.google.errorprone.CompilationTestHelper;
+import com.google.errorprone.util.RuntimeVersion;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -24,6 +28,10 @@
 /** {@link SwitchDefault}Test */
 @RunWith(JUnit4.class)
 public class SwitchDefaultTest {
+
+  private final CompilationTestHelper compilationHelper =
+      CompilationTestHelper.newInstance(SwitchDefault.class, getClass());
+
   private final BugCheckerRefactoringTestHelper testHelper =
       BugCheckerRefactoringTestHelper.newInstance(SwitchDefault.class, getClass());
 
@@ -224,4 +232,63 @@ public void refactoring_outOfOrder() {
             "}")
         .doTest();
   }
+
+  @Test
+  public void newNotation_validDefault() {
+    assumeTrue(RuntimeVersion.isAtLeast14());
+    compilationHelper
+        .addSourceLines(
+            "Test.java",
+            "class Test {",
+            "  public static void nothing1() { }",
+            "  public static void nothing2() { }",
+            "  public static void nothing3() { }",
+            "  public static void switchDefaultCrash(int i)",
+            "  {",
+            "        switch(i) {",
+            "            case 0 -> nothing1();",
+            "            case 1 -> nothing2();",
+            "            default -> nothing3();",
+            "        }",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  public void newNotation_changeOrder() {
+    assumeTrue(RuntimeVersion.isAtLeast14());
+    testHelper
+        .addInputLines(
+            "Test.java",
+            "class Test {",
+            "  public static void nothing1() { }",
+            "  public static void nothing2() { }",
+            "  public static void nothing3() { }",
+            "  public static void switchDefaultCrash(int i)",
+            "  {",
+            "        switch(i) {",
+            "            default -> nothing3();",
+            "            case 0 -> nothing1();",
+            "            case 1 -> nothing2();",
+            "        }",
+            "  }",
+            "}")
+        .addOutputLines(
+            "Test.java",
+            "class Test {",
+            "  public static void nothing1() { }",
+            "  public static void nothing2() { }",
+            "  public static void nothing3() { }",
+            "  public static void switchDefaultCrash(int i)",
+            "  {",
+            "        switch(i) {",
+            "            case 0 -> nothing1();",
+            "            case 1 -> nothing2();",
+            "            default -> nothing3();",
+            "        }",
+            "  }",
+            "}")
+        .doTest();
+  }
 }