Update re2

third_party/re2/util/stringprintf.cc

Index: third_party/re2/util/stringprintf.cc
diff --git a/third_party/re2/util/stringprintf.cc b/third_party/re2/util/stringprintf.cc
index c908181e56556fcdbb737c67930d1dd7f627e110..e71d993861f5da28d70816caaa62f18da9a574c9 100644
--- a/third_party/re2/util/stringprintf.cc
+++ b/third_party/re2/util/stringprintf.cc
@@ -4,7 +4,7 @@
 
 #include "util/util.h"
 
-namespace re2 { 
+namespace re2 {
 
 static void StringAppendV(string* dst, const char* format, va_list ap) {
   // First try with a small fixed size buffer
@@ -18,7 +18,7 @@ static void StringAppendV(string* dst, const char* format, va_list ap) {
   int result = vsnprintf(space, sizeof(space), format, backup_ap);
   va_end(backup_ap);
 
-  if ((result >= 0) && (result < sizeof(space))) {
+  if ((result >= 0) && (static_cast<unsigned long>(result) < sizeof(space))) {
     // It fit
     dst->append(space, result);
     return;
@@ -38,7 +38,14 @@ static void StringAppendV(string* dst, const char* format, va_list ap) {
 
     // Restore the va_list before we use it again
     va_copy(backup_ap, ap);
+#if !defined(_WIN32)
     result = vsnprintf(buf, length, format, backup_ap);
+#else
+    // On Windows, the function takes five arguments, not four. With an array,
+    // the buffer size will be inferred, but not with a pointer. C'est la vie.
+    // (See https://github.com/google/re2/issues/40 for more details.)
+    result = vsnprintf(buf, length, _TRUNCATE, format, backup_ap);
+#endif
     va_end(backup_ap);
 
     if ((result >= 0) && (result < length)) {