From The Document Foundation Wiki
- ABI backwards-compatibility for compiled extensions. There is some resistance to breaking that.
- So far MSVC produces faster, smaller binaries.
- There are some features in the code that don't compile with MinGW. They use API that MinGW does not provide headers for etc.
- There are open questions around how we would run unit tests in a MinGW cross-compilation environment.
- There are open questions around how well gdb works on Windows; the MSVC C++ debugger is really quite good.