Windows installation fails building ink_linting

[ascjones]

Recently the windows CI has started to fail with Error: environment variable not found: RUSTUP_TOOLCHAIN from the dylint-link linker.

So the build.rs does in fact remove this environment variable, which is required so as not to override the required version for the child cargo invocation in the ink_linting/rust-toolchain file. However this has always worked previously and it also continues to work on Linux. My current working assumption is that there is a bug in the recent 1.25 release of rustup perhaps by not setting RUSTUP_TOOLCHAIN for the child process where it should. There seem to be a couple of other windows specific issues e.g. rust-lang/rustup#3036, but not exactly the same issue we are having.

I have rolled back rustup to 1.24.3 on a local Windows machine and that seems to fix the issue, however there doesn't seem to be a way to control the version of rustup installed via actions-krs.

A couple of ideas of how to proceed:

1. Confirm issue is in rustup and find and fix it.
2. Remove the cmd.env_remove("RUSTUP_TOOLCHAIN"); line in build.rs and instead add +nightly-2022-06-30 (from the rust-toolchain file). This arg would take precedence over the current RUST_TOOLCHAIN. One issue with this is that 1.25 also has a bug which currently prevents this.

[bugproof]

So cargo install cargo-contract is broken on Windows?

[ascjones]

So cargo install cargo-contract is broken on Windows?

With the latest version of rustup, yes.