Fix stupid build error caused by a stupid person

llvm-svn: 290656
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 8dd73d8e067542f251960368c50812f646d55e47
diff --git a/include/__debug b/include/__debug
index 337793d..2a45710 100644
--- a/include/__debug
+++ b/include/__debug
@@ -54,6 +54,9 @@
 
 struct _LIBCPP_TYPE_VIS_ONLY __libcpp_debug_info {
   _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
+  __libcpp_debug_info()
+      : __file_(nullptr), __line_(-1), __pred_(nullptr), __msg_(nullptr) {}
+  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
   __libcpp_debug_info(const char* __f, int __l, const char* __p, const char* __m)
     : __file_(__f), __line_(__l), __pred_(__p), __msg_(__m) {}
   const char* __file_;