Continuous integration issues (Gitlab-CI, Travis-CI, Appveyor)

Issues involving the Cygwin Unix-emulation runtime on Windows

Deprecated functionality, features that might be removed, platform support that might be dropped

FreeBSD and closely related OSs

Issue is specific to Linux

Issue is specific to macOS

gcc compilers that produce native Windows executables targeting MSVCRT

MSYS2 Unix-emulation environment on Windows

You had a problem, so you solved it with threads, and two now problem you (Segmentation fault, core dumped.)