Patch re2 to support MSan.

third_party/re2/patches/re2-msan.patch

Index: third_party/re2/patches/re2-msan.patch
diff --git a/third_party/re2/patches/re2-msan.patch b/third_party/re2/patches/re2-msan.patch
new file mode 100644
index 0000000000000000000000000000000000000000..08b7bde9d64197e43d3f2b27b5e5abdd2dc7d8e3
--- /dev/null
+++ b/third_party/re2/patches/re2-msan.patch
@@ -0,0 +1,62 @@
+diff --git a/third_party/re2/util/sparse_array.h b/third_party/re2/util/sparse_array.h
+index 3e33f89..613417d 100644
+--- a/third_party/re2/util/sparse_array.h
++++ b/third_party/re2/util/sparse_array.h
+@@ -231,7 +231,14 @@ class SparseArray {
+ 
+ template<typename Value>
+ SparseArray<Value>::SparseArray()
+-    : size_(0), max_size_(0), sparse_to_dense_(NULL), dense_(), valgrind_(RunningOnValgrind()) {}
++    : size_(0), max_size_(0), sparse_to_dense_(NULL), dense_(),
++#if defined(MEMORY_SANITIZER)
++    valgrind_(true)
++#else
++    valgrind_(RunningOnValgrind())
++#endif
++{
++}
+ 
+ // IndexValue pairs: exposed in SparseArray::iterator.
+ template<typename Value>
+@@ -418,7 +425,11 @@ void SparseArray<Value>::create_index(int i) {
+ template<typename Value> SparseArray<Value>::SparseArray(int max_size) {
+   max_size_ = max_size;
+   sparse_to_dense_ = new int[max_size];
++#if defined(MEMORY_SANITIZER)
++  valgrind_ = true;
++#else
+   valgrind_ = RunningOnValgrind();
++#endif
+   dense_.resize(max_size);
+   // Don't need to zero the new memory, but appease Valgrind.
+   if (valgrind_) {
+diff --git a/third_party/re2/util/sparse_set.h b/third_party/re2/util/sparse_set.h
+index 165dd09..f59ed0b 100644
+--- a/third_party/re2/util/sparse_set.h
++++ b/third_party/re2/util/sparse_set.h
+@@ -54,13 +54,24 @@ namespace re2 {
+ class SparseSet {
+  public:
+   SparseSet()
+-    : size_(0), max_size_(0), sparse_to_dense_(NULL), dense_(NULL), valgrind_(RunningOnValgrind()) {}
++    : size_(0), max_size_(0), sparse_to_dense_(NULL), dense_(NULL),
++#if defined(MEMORY_SANITIZER)
++      valgrind_(true)
++#else
++      valgrind_(RunningOnValgrind())
++#endif
++  {
++  }
+ 
+   SparseSet(int max_size) {
+     max_size_ = max_size;
+     sparse_to_dense_ = new int[max_size];
+     dense_ = new int[max_size];
++#if defined(MEMORY_SANITIZER)
++    valgrind_ = true;
++#else
+     valgrind_ = RunningOnValgrind();
++#endif
+     // Don't need to zero the memory, but do so anyway
+     // to appease Valgrind.
+     if (valgrind_) {