rust-lang / rust-lang/rust

regression: crate compiles much slower with 1.82

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#132,064 25 comments 5 reactions 0 assignees View on GitHub

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C-bug I-compiletime regression-from-stable-to-stable T-compiler
Dominant language
Rust
Stars
119k
Forks
16.1k
PR merge metrics
PR metrics pending

Description

Our project takes much longer to compile with Rust 1.82 compared to previous versions. To reproduce, git clone https://github.com/LemmyNet/lemmy.git and run cargo check (also happens with build or lint). The problem happens specifically with the crate lemmy_db_views.

cargo check with 1.82: 6m 19s

cargo check with 1.81: 1m 22s

Version it worked on

It most recently worked on:1.81

Version with regression

rustc --version --verbose:

cargo 1.82.0 (8f40fc59f 2024-08-21)
release: 1.82.0
commit-hash: 8f40fc59fb0c8df91c97405785197f3c630304ea
commit-date: 2024-08-21
host: x86_64-unknown-linux-gnu
libgit2: 1.8.1 (sys:0.19.0 vendored)
libcurl: 8.9.0-DEV (sys:0.4.74+curl-8.9.0 vendored ssl:OpenSSL/1.1.1w)
ssl: OpenSSL 1.1.1w  11 Sep 2023
os: Manjaro 24.1.1 (Xahea) [64-bit]

@rustbot modify labels: +regression-from-stable-to-1.82 -regression-untriaged

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Clone Lemmy and compare cargo check, build, or lint on Rust 1.81 and 1.82 for the lemmy_db_views crate. Investigate the compiler-related cause of the reported slowdown; done means the regression is fixed or narrowed to an actionable explanation or minimal reproduction.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers, performance
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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