[geraldcombs]

For us (Wireshark) the difficulty wasn't with our own codebase, but with getting our dependencies ported over. Most libraries built just fine, but some strongly assumed that "Windows" meant "x86".

It's not just Windows, either. Many libraries (particularly ones that use Autotools) are absolutely blind to the notion that you might want a universal binary on macOS.

[astrange]

When we ported OpenJDK to macOS, I ended up producing a universal binary by having the Makefile run itself to produce HotSpot twice, and then gluing them together with `lipo` afterwards. There isn't really a better way when the actual project configurations are different.

IIRC it was eventually removed because nobody else needed to do such a thing so it was hard to maintain.

[kccqzy]

Sure. How else would you build a universal binary then? Given the low-level nature of the language not many tasks can be usefully shared between different architectures.