JalanChao

```cpp #include #include template < bool AddOrRemoveRef > struct Fun_; template struct Fun_< true > { template < typename T > using type = std::add_lvalue_reference< T >; }; template struct...

Fix the issue that prevents compilation in C++11 environment

2

issue #1247 [Commit 302786e ](https://github.com/google/leveldb/commit/302786e211d1f2e6fd260261f642d03a91e5922c) introduced a definition std::is_standard_layout_v that is only supported starting from C++17, which now prevents the LevelDB project from compiling in a C++11 environment. This modification...