Hang : `rustc` hangs/OOMs with infinite recursion
Open
Nobody has claimed this yet.
C-bug
fixed-by-next-solver
I-compilemem
I-hang
T-compiler
- Dominant language
- Rust
- Stars
- 119k
- Forks
- 16.1k
- PR merge metrics
- PR metrics pending
Description
The compiler hangs and causes a Memory Leak.
I tried this code:
trait Baz: Grault {}
impl Baz for () {}
impl<T> Baz for (T,) {}
trait Fiz {}
impl Fiz for bool {}
trait Grault {
type A;
type B;
}
impl<T: Grault> Grault for (T,)
where
Self::A: Baz,
Self::B: Fiz,
{
type A = ();
type B = bool;
}
fn main() {
let x: <(_,) as Grault>::A = ();
}
Meta
rustc --version --verbose:
rustc 1.92.0 (ded5c06cf 2025-12-08)
binary: rustc
commit-hash: ded5c06cf21d2b93bffd5d884aa6e96934ee4234
commit-date: 2025-12-08
host: x86_64-unknown-linux-gnu
release: 1.92.0
LLVM version: 21.1.3
rustc 1.94.0-nightly (e29fcf45e 2026-01-04)
binary: rustc
commit-hash: e29fcf45e4ae686d77b490bf07320f0d3a2cf35f
commit-date: 2026-01-04
host: x86_64-unknown-linux-gnu
release: 1.94.0-nightly
LLVM version: 21.1.8
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 compiling the provided minimal Rust program with the stable and nightly rustc versions listed, confirming the hang or out-of-memory behavior. Trace the compiler's handling of the recursive trait and associated-type obligations; done means compilation terminates safely and a regression test covers this reproducer.
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