Don't neglect to "return *this".


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@165860 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/regex b/include/regex
index 3918ee0..7505f2e 100644
--- a/include/regex
+++ b/include/regex
@@ -2562,6 +2562,7 @@
         {
             __member_init(__f);
             __parse(__first, __last);
+            return *this;
         }
 
 #ifndef _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS