[davidt84]

Hmm, I'm apparently correct for C++11, where calling getenv only is thread safe, but that's not guaranteed by earlier standards (or, as far as I can tell, by C or POSIX).

[kazinator]

I'm surprised C++ would have anything to say about getenv; mostly it just includes the standard C library via normative reference.

[davidt84]

Nevertheless, https://en.cppreference.com/w/cpp/utility/program/getenv

[kazinator]

Interesting. So in a multi-threaded C++ program that only calls the std:: getenv function, everything is fine.

If anything calls the C getenv function, like a third party library, things are maybe not fine.