Miri can't find crate after toolchain update

[vertexclique]

So our project was using toolchain version nightly-2020-06-10 with miri like:

rustup component add miri rustfmt
cargo miri setup
cargo clean
cargo miri test

after updating toolchain to nightly-2020-09-28 same build continuously fails with:

error[E0463]: can't find crate for `array_tool`
   --> /home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/jsonpath_lib-0.2.5/src/lib.rs:125:1
    |
125 | extern crate array_tool;
    | ^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate

Though, in the previous toolchain version that Miri has been shipped, this wasn't an issue. Any idea what might be going wrong?

P.S. We've changed the flag passing to MIRIFLAGS with MIRIFLAGS="-Zmiri-disable-isolation".

[RalfJung]

That is strange, it seems we're doing something wrong in our cargo wrapper.

Do you have an example project you could point me to that reproduces the problem?

[RalfJung]

@vertexclique I'm afraid without a way to reproduce the problem or some further details there is not much I can do here -- since this works with many other crates, there is likely something specific to your setup/crate that is causing this.

Can you share the output of cargo miri test -v (after a cargo clean)?

[vertexclique]

@RalfJung You can find the MCVE here: https://github.com/vertexclique/miri-mcve

[oli-obk]

the only thing I'm seeing that could be relevant here just from looking at the source is that jsonpath_lib has a crate-type = ["cdylib", "rlib"] in its Cargo.toml

[RalfJung]

Yeah, rustc was trying and failing to build an rlib/cdylib for this. Turns out we can just skip that build, nobody needs it anyway.