You're thinking of cross platform codebases. There's nothing about cross compilation that stops the toolchain from knowing what APIs are present & not present on a target system.
Cross compilation and cross platform are synonymous in compiled languages, in regards of many issues that one needs to care about.
Cross platform goes beyond in regards to UI, direction locations, user interactions,...
Yeah, if you happen to have systemd Linux libraries on macOS to facilitate cross compilation into a compatible GNU/Linux system than it works, that is how embedded development has worked for ages.
What doesn't work is pretending that isn't something to care about.
> Cross compilation and cross platform are synonymous in compiled languages
Err, no. Cross-platform means the code can be compiled natively on each platform. Cross-compilation is when you compile the binaries on one platform for a different platform.
Not at all, cross platform means executing the same application in many platforms, regardless of the hardware and OS specific features of each platform.
Cross-compilation is useless if you don't actually get to executed the created binaries in the target platform.
Now, how do you intend to compile from GNU/Linux into z/OS, so that we can execute the generated binary out from the C compiler ingesting the code written in GNU/Linux platform, in the z/OS language environment inside an enclave, not configured in POSIX mode?
Using z/OS, if you're feeling more modern, it can be UWP sandboxed application with identity in Windows.
> cross platform means executing the same application in many platforms, regardless of the hardware and OS specific features of each platform.
That is a better definition yes. But it's still not synonymous with cross-compilation, obviously. Most cross-platform apps are not cross-compiled because it's usually such a pain.
