clang-format: Fix crasher when splitting incomplete escape sequences.

llvm-svn: 226698
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 553368d..7c86d14 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -7444,6 +7444,12 @@
   EXPECT_EQ("@\"NSString \"\n"
             "@\"literal\";",
             format("@\"NSString literal\";", getGoogleStyleWithColumns(19)));
+
+  // This input makes clang-format try to split the incomplete unicode escape
+  // sequence, which used to lead to a crasher.
+  verifyNoCrash(
+      "aaaaaaaaaaaaaaaaaaaa = L\"\\udff\"'; // aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+      getLLVMStyleWithColumns(60));
 }
 
 TEST_F(FormatTest, DoesNotBreakRawStringLiterals) {