Why does GCC-Windows depend on cygwin?

Question

I\'m not a C++ developer, but I\'ve always been interested in compilers, and I\'m interested in tinkering with some of the GCC stuff (particularly LLVM).

On Windows,

Answer 1

Windows does not offer a standard POSIX library so cygwin provides one (cygwin1.dll). The gcc packages that comes with cygwin uses it.

mingw, on the other hand, does not necessarely provide a POSIX layer. The mingw installation that I use, for example, does not even have a pthread library.

Should I need it I would have to install it. Mingw-gcc produces Win32 native code (and in fact relies on MSVCRT.DLL).

EDIT: reading your edit I'm no longer sure if you're asking why gcc itself needs mingw/cygwin libraries or if the programs compiled with gcc on Win require those libraries