> By using a compiler that doesn't know how to handle the target for a start.
Being limited to mimicking the Android/x32 ABI via target.c in the compiler frontend to make sure it passes semantic only is likely to raise more false positives than solutions.

Pretty sure this particular cast has nothing to do with the workings of the compiler, as all the relevant type definitions are in druntime and phobos.  The compiler is merely verifying them and noting the mismatch.

> __USE_FILE_OFFSET64 should be true for Android. For the intent of compatibility, all programs that interface to D should define LARGEFILE64 before including sys/stat.h.

There is no `__USE_FILE_OFFSET64` or `__USE_LARGEFILE64` in the Android headers.  Better to modify `File.seek` in phobos to use `off_t offset`, as that's the real API for `fseeko` anyway.