Constant winit::platform_impl::platform::BACKEND_PREFERENCE_ENV_VAR

const BACKEND_PREFERENCE_ENV_VAR: &str = "WINIT_UNIX_BACKEND";

Environment variable specifying which backend should be used on unix platform.

Legal values are x11 and wayland. If this variable is set only the named backend will be tried by winit. If it is not set, winit will try to connect to a wayland connection, and if it fails will fallback on x11.

If this variable is set with any other value, winit will panic.