Type checking bug. Trait appears to use inferred type from bounds rather than specified associated type
Nobody has claimed this yet.
- Dominant language
- Rust
- Stars
- 119k
- Forks
- 16.1k
- PR merge metrics
- PR metrics pending
Description
I tried this code:
https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=9b8e4a4b196fdb3320c694d180649731
I expected to see this happen: borrow should be known to return (), as it is specified to return an associated type that is specified just three lines earlier.
Instead, this happened: A compiler error citing an equivalent type saying it isn't known to be ().
Meta
rustc --version --verbose:
rustc 1.81.0-nightly (6e2780775 2024-07-05)
binary: rustc
commit-hash: 6e2780775f5cea9328d37f4b8d0ee79db0056267
commit-date: 2024-07-05
host: x86_64-unknown-linux-gnu
release: 1.81.0-nightly
LLVM version: 18.1.7
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by running the linked Rust Playground reproduction on the stable or nightly compiler and compare the diagnostic with the stated expectation for the associated type. Trace the compiler's type-checking path for the trait and its bounds; done means the example recognizes the specified return type without the reported error and has a regression test.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100