Why compile under an older c++ version

[CABrouwers]

Is there any reason to compile under an older version of C++ and not the most current stable one? For example, I code on AWS cloud9, whose default script calls g++ with the -std=c++11 option. Is there any downside in changing that to c++17?

[JLBorges]

> Is there any reason to compile under an older version of C++ and not the most current stable one?

For new code, no. Ideally use the most current stable version available on the platform.

For a large existing code base, which has been in development over a number of years, switching to a newer version may not be immediate. If the software is near the end of its development life-time, it may not be worthwhile to invest in the effort to retest everything.