здесь
Ну, будем пробовать.
UPD. Опция -std=
‘c++20’
‘c++2a’ The next revision of the ISO C++ standard, planned for 2020. Support is highly experimental, and will almost certainly change in incompatible ways in future releases.
‘gnu++20’
‘gnu++2a’ GNU dialect of ‘-std=c++20’. Support is highly experimental, and will almost certainly change in incompatible ways in future releases
На свой страх и риск.