Unexpected internal error when doing nightly build and then stable build

[mtkennerly]

Problem

I had Rust stable 1.44.1 installed and working fine. I then added nightly and did a build with:

rustup toolchain install nightly --allow-downgrade
cargo +nightly run --release

which worked fine. Then I tried to build on stable again, and I got an error:

$ cargo run --release
error: dep-info invalid
note: this is an unexpected cargo internal error
note: we would appreciate a bug report: https://github.com/rust-lang/cargo/issues/
note: cargo 1.44.1 (88ba85757 2020-06-11)

However, cargo run (without --release) still works.

Steps

Method A:

1. cargo clean
2. cargo run --release
3. cargo +nightly run --release
4. cargo run --release

Method B:

1. cargo clean
2. cargo +nightly run --release
3. cargo run --release
4. cargo +nightly run --release
   • This invocation only showed incremental build output, whereas the other invocations resulted in full builds:
5. cargo run --release

Possible Solution(s)

Just a workaround, but cargo clean resolves the issue.

Notes

Output of cargo version:

cargo 1.44.1 (88ba85757 2020-06-11)

• OS: Windows 10
• Toolchains: stable-x86_64-pc-windows-msvc (default) and nightly-x86_64-pc-windows-msvc

[ehuss]

Thanks for the report!

This is essentially the same as #8298, though triggered by a different change (#8421). The repro:

1. Create a project with dylib or cdylib crate type.
2. cargo +nightly-2020-07-06 build
3. cargo +1.44.1 build

I should have remembered that case during review, since I had just been looking at #8298.

[alexcrichton]

I've tried to fix this in #8473 by ensuring that the reason bin/rlib works works for dylib/cdylib as well.