doctests in libcore sometimes use wrong external crate

[RalfJung]

Under some circumstances, Miri goes all crazy on libcore doctests: it seems to load two distinct copies of libcore and then hell breaks loose.

Specifically, this seems to be triggered when the code contains a variable that does not exist -- rustc will try to make szggestions for names to use, which can trigger loading external crates, which might be what is happening here.

I think this issue belongs to https://github.com/rust-lang/miri-test-libstd. cargo test without Miri fails with same errors in that repository and all other libcore tests passed. It's caused by the miri-test-libstd-specific core_miri_test crate which is effectively another libcore.

[RalfJung]

Ah I see, thanks. I can't transfer issues there so I'll do that by hand.

[RalfJung]

Moved to rust-lang/miri-test-libstd#4