Miri does not support file system access

[RalfJung]

This issue tracks Miri not supporting all sorts of file system access APIs, from working directories to directory listing to actual read/writes. Such access should be possible when -Zmiri-disable-isolation is set. But it will be quite some work to implement dozens of shims for our 3 supported platforms.

If you are running into this, I suggest trying to carve out a part of your library does can run on "pure data", without accessing the file system. That part you should then be able to test in Miri.

[pvdrz]

I think this has been covered well enough for unix-like platforms. The current state is that miri can create, write, read and delete files when isolation is disabled: https://github.com/rust-lang/miri/blob/master/tests/run-pass/fs.rs

[RalfJung]

That sounds like a good start, let's use more targeted issues when more APIs get requested.

Thanks a lot @christianpoveda for helming this. :)