From b9b492f554e1e12da2d3777a8e4e76095fda63bf Mon Sep 17 00:00:00 2001
From: dfielder <dfielder@google.com>
Date: Fri, 30 Jun 2017 13:55:18 -0700
Subject: [PATCH] Fix NPE in AbstractReturnValueIgnored for lambdas.

Fixes #657

RELNOTES: Fixes a null pointer exception in AbstractReturnValueIgnored on expression-type lambdas.

MOE_MIGRATED_REVID=160684735
---
 .../com/google/errorprone/matchers/IsLastStatementInBlock.java | 2 +-
 .../bugpatterns/testdata/ReturnValueIgnoredPositiveCases.java  | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/check_api/src/main/java/com/google/errorprone/matchers/IsLastStatementInBlock.java b/check_api/src/main/java/com/google/errorprone/matchers/IsLastStatementInBlock.java
index 35745a76fe0..c7377270891 100644
--- a/check_api/src/main/java/com/google/errorprone/matchers/IsLastStatementInBlock.java
+++ b/check_api/src/main/java/com/google/errorprone/matchers/IsLastStatementInBlock.java
@@ -28,6 +28,6 @@ public class IsLastStatementInBlock<T extends StatementTree> implements Matcher<
   public boolean matches(T statement, VisitorState state) {
     BlockTree block = state.findEnclosing(BlockTree.class);
 
-    return Iterables.getLast(block.getStatements()).equals(statement);
+    return block != null && Iterables.getLast(block.getStatements()).equals(statement);
   }
 }
diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/testdata/ReturnValueIgnoredPositiveCases.java b/core/src/test/java/com/google/errorprone/bugpatterns/testdata/ReturnValueIgnoredPositiveCases.java
index 1a94e741e84..f35d2280857 100644
--- a/core/src/test/java/com/google/errorprone/bugpatterns/testdata/ReturnValueIgnoredPositiveCases.java
+++ b/core/src/test/java/com/google/errorprone/bugpatterns/testdata/ReturnValueIgnoredPositiveCases.java
@@ -27,6 +27,9 @@
 public class ReturnValueIgnoredPositiveCases {
   String a = "thing";
 
+  // BUG: Diagnostic contains: Return value of this method must be used
+  private Runnable r = () -> String.valueOf("");
+
   { // String methods
     // BUG: Diagnostic contains: remove this line
     String.format("%d", 10);