From c03fd9b73f75e78d631c9ce14d9ea3fd4d4909af Mon Sep 17 00:00:00 2001
From: Lucian Grijincu <lucian@fb.com>
Date: Mon, 9 May 2016 17:50:08 -0700
Subject: [PATCH] folly: ubsan: fix "reference binding to null pointer of type
 'char'"

Summary:
third-party-buck/build/libgcc/include/c++/4.9.x/bits/stl_vector.h:866:9: runtime error: reference binding to null pointer of type 'char'

```
Breakpoint 2, 0x0000000000494894 in __ubsan_handle_type_mismatch_abort ()
(gdb) bt
```

Reviewed By: meyering, yfeldblum

Differential Revision: D3279234

fbshipit-source-id: 63a761587e5b3f79ece09fc99b9a593da0e44b75
---
 folly/test/FBStringTest.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/folly/test/FBStringTest.cpp b/folly/test/FBStringTest.cpp
index 34858238..3d39b773 100644
--- a/folly/test/FBStringTest.cpp
+++ b/folly/test/FBStringTest.cpp
@@ -574,10 +574,10 @@ template <class String> void clause11_21_4_6_6(String & test) {
 template <class String> void clause11_21_4_6_7(String & test) {
   std::vector<typename String::value_type>
     vec(random(0, maxString));
-  test.copy(
-    &vec[0],
-    vec.size(),
-    random(0, test.size()));
+  if (vec.empty()) {
+    return;
+  }
+  test.copy(vec.data(), vec.size(), random(0, test.size()));
 }
 
 template <class String> void clause11_21_4_6_8(String & test) {
-- 
2.34.1