Version 9.1 of the GCC compiler suite is out. "In this release C++17 support is no longer marked experimental. The C++ front-end implements the full C++17 language (already previous GCC major version implemented that) and the C++ standard library support is almost complete. The C++ front-end and library also have numerous further C++2a draft features. GCC has a new front-end for the D language. GCC 9.1 has newly partial OpenMP 5.0 support and almost complete OpenACC 2.5 support." See this page for an extensive list of changes.