These loaders will provide pointers to the platform implementation of OpenGL. On Android, Linux and Darwin, we simply link with the OpenGL implementation that is expected to exist on the platform. Qt has its own GL loader, so we just connect the dots.
Darwin
The code in the Darwin platform targets Apple platforms but is not specific to iOS or macOS. This code is not distributed as an SDK in itself, but is required by the Mapbox iOS SDK and Mapbox macOS SDK.
These files depend on the Foundation and Core Foundation frameworks but do not depend on iOS- or macOS–specific frameworks, such as UIKit or AppKit. Any non-cross-platform code is guarded by TargetConditionals.h macros.