On MacOS std::fs::copy does not modify the timestamp of the destination #115982

I was just debugging different behavior between Linux and MacOS builds in our CI, and it turns out, it came to sqlite-sys crate using build.rs script that uses std::fs::copy, which on MacOS seems to be using fcopyfile call which preserves the modification, access, and creation timestamps from the source file to the destination file by default.

This is an inconsistency with implementations on other platforms, I believe.

It seems that COPYFILE_STAT flag could be turned off on that call, but that will also prevent mode from being copied, which seems copied on other implementations. So AFAICT making behavior consistent would cost an extra syscall.

Unless I'm mistaken somewhere altogether (happens a lot), at very least this should be explicitly documented.

Personally, I would prefer this being made consistent. As unreliable as they can sometimes be mtimes are often used for things like caching, and it's no fun to hunt down weird caching bugs etc. that happen only on one platform.