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Panic with "already borrowed: BorrowMutError" since nightly-2024-03-26 #13646
Description
Problem
Since nightly-2024-03-26, -Z minimal-versions and -Z direct-minimal-versions panic on some my projects when lockfile is already exists.
EDIT: this seems to be reproducible without -Z minimal-versions/-Z direct-minimal-versions: #13646 (comment)
Steps
$ git clone https://github.com/taiki-e/easytime
$ cd easytime
$ cargo generate-lockfile
$ cargo update -Z minimal-versions
Updating crates.io index
Downgrading aho-corasick v1.1.3 -> v0.6.0 (latest: v1.1.3)
Downgrading anyhow v1.0.81 -> v1.0.0 (latest: v1.0.81)
thread 'main' panicked at src/cargo/util/context/mod.rs:412:20:
already borrowed: BorrowMutError
stack backtrace:
0: _rust_begin_unwind
1: core::panicking::panic_fmt
2: core::cell::panic_already_borrowed
3: <cargo::util::progress::State>::tick
4: <cargo::sources::registry::http_remote::HttpRegistry as cargo::sources::registry::RegistryData>::block_until_ready
5: <cargo::sources::registry::RegistrySource as cargo::sources::source::Source>::block_until_ready
6: <cargo::sources::replaced::ReplacedSource as cargo::sources::source::Source>::block_until_ready
7: <cargo::core::registry::PackageRegistry as cargo::core::registry::Registry>::block_until_ready
8: cargo::ops::cargo_generate_lockfile::print_lockfile_updates
9: cargo::ops::cargo_generate_lockfile::update_lockfile
10: cargo::commands::update::exec
11: <cargo::cli::Exec>::exec
12: cargo::cli::main
13: cargo::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.It can be work around by removing Cargo.lock before calling -Z minimal-versions.
It can also be reproduced with https://github.com/taiki-e/pin-project-lite.
It can also be reproduced with -Z direct-minimal-versions.
$ cargo minimal-versions build --workspace --no-private --detach-path-deps=skip-exact --all-features --direct
info: running `cargo update -Z direct-minimal-versions`
thread 'main' panicked at src/cargo/util/context/mod.rs:412:20:
already borrowed: BorrowMutErrorPossible Solution(s)
No response
Notes
No response
Version
cargo 1.79.0-nightly (a510712d0 2024-03-25)
release: 1.79.0-nightly
commit-hash: a510712d05c6c98f987af24dd73cdfafee8922e6
commit-date: 2024-03-25
host: aarch64-apple-darwin
libgit2: 1.7.2 (sys:0.18.2 vendored)
libcurl: 8.4.0 (sys:0.4.72+curl-8.6.0 system ssl:(SecureTransport) LibreSSL/3.3.6)
ssl: OpenSSL 1.1.1w 11 Sep 2023
os: Mac OS 14.4.0 [64-bit]
Activity
dtolnay commentedon Mar 26, 2024
I also observed this in https://github.com/dtolnay/rustversion/actions/runs/8429673336/job/23084341781, in which I use neither
-Zminimal-versionsnor-Zdirect-minimal-versions. Seems like a broader issue. Nightly-2024-03-26 is the first version affected in my case as well.[-]-Z minimal-versions and -Z direct-minimal-versions panic with "already borrowed: BorrowMutError" since nightly-2024-03-26[/-][+]Panic with "already borrowed: BorrowMutError" since nightly-2024-03-26[/+]dtolnay commentedon Mar 26, 2024
Bisects to #13561 and specifically 4ab2797, using
cargo testin the rustversion repo. @epagetaiki-e commentedon Mar 26, 2024
From a quick look at the panic location (GlobalContext::shell), backtrace, and #13561 diff, it appears to be related to the fact that BorrowMut (returned by GlobalContext::shell), which previously persisted only during printing, now persists for the entire print_lockfile_updates.
Auto merge of rust-lang#123081 - Muscraft:update-cargo, r=Muscraft
epage commentedon Mar 26, 2024
So it appears the reason manual testing and the test suite didn't hit this is there wasn't contention over the package lock. In fact, we only have one test that even attempts to capture the Blocking status.
We could try to make a specific test case to prevent regressions in this one case but then we'd likely run into this in other places. As an alternative, we could do a useless borrow of
shell()further up the stack where it'd be unconditional so tests would be more likely to catch this.weihanglo commentedon Mar 26, 2024
I wonder How it looks like and how it applies to other RefCell usages in the codebase.
test: Add asserts to catch BorrowMutError's
test: Add asserts to catch BorrowMutError's
Auto merge of #13651 - weihanglo:borrow_mut, r=epage
test: Add asserts to catch BorrowMutError's