rust-analyzer can invoke build scripts with RUSTC_BOOTSTRAP=1, wreaking havoc on feature detection

[SludgePhD]

rust-analyzer version: 0.3.1541

rustc version: rustc 1.70.0 (90c541806 2023-05-31)

relevant settings:

• "rust-analyzer.cargo.buildScripts.useRustcWrapper": false,

Some crates (for instance anyhow and thiserror) determine whether they are being built by a supported nightly compiler by performing a trial compilation in their build script (think autotools). It seems like rust-analyzer will invoke build scripts while having RUSTC_BOOTSTRAP set (perhaps only under some circumstances), which makes those crates think they can use nightly features.

This appears to "work" in rust-analyzer, and "poisons" the build cache with the build script output. A later cargo run in the terminal will then reuse the build script output, and build the crate in question without having RUSTC_BOOTSTRAP set, leading to errors like this:

error[E0554]: `#![feature]` may not be used on the stable release channel
   --> /home/sludge/.cargo/registry/src/index.crates.io-6f17d22bba15001f/anyhow-1.0.71/src/lib.rs:214:32
    |
214 | #![cfg_attr(backtrace, feature(error_generic_member_access, provide_any))]
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0554]: `#![feature]` may not be used on the stable release channel
   --> /home/sludge/.cargo/registry/src/index.crates.io-6f17d22bba15001f/anyhow-1.0.71/src/lib.rs:214:61
    |
214 | #![cfg_attr(backtrace, feature(error_generic_member_access, provide_any))]
    |                                                             ^^^^^^^^^^^

This has previously been reported in dtolnay/thiserror#192 as affecting users that have rust-analyzer.cargo.buildScripts.useRustcWrapper enabled (the default), while I have it disabled, so it seems that the setting may be a red herring and doesn't matter.

[loynoir]

Got same error when dtolnay/thiserror and dtolnay/anyhow in dependency tree.

At the same time, I use sccache.

Try below does not working.

• "rust-analyzer.cargo.buildScripts.useRustcWrapper": false

Then

• disable RA

• cargo clean

• build

Now seems working correctly.

[lnicola]

This should have been fixed in #12973 / #13010. anyhow works fine for me. Which versions are you using, and does it happen in a new project?

[loynoir]

Yes, recent project, maybe 1~2 weeks.

Old cache deleted, did not backup for reproduce.

[loynoir]

Now, I try with

        "rust-analyzer.cargo.buildScripts.useRustcWrapper": true,
        "rust-analyzer.rust.analyzerTargetDir": "{{RA_TARGET}}"

Guess in this way will not pollute real build cache forever.

Hope will not happen again.

[lnicola]

It works fine for me without changing any settings. Are you sure you're not running a very old version of RA? And please try in an empty project (with anyhow as a dep).

[loynoir]

RA v0.3.1705.

FYI. I depend on X, and X deep dependency depends on dtolnay/thiserror and dtolnay/anyhow.

Background, rust newbie.

[Veykril]

This should be fixed?

[txase]

This issue isn't fixed yet. I posted PR #16621 to fix it.