Compiler hangs and consumes unbounded memory with complex trait bounds
Open
Nobody has claimed this yet.
A-trait-system
C-bug
fixed-by-next-solver
I-compilemem
I-hang
T-types
- Dominant language
- Rust
- Stars
- 119k
- Forks
- 16.1k
- PR merge metrics
- PR metrics pending
Description
I tried this code:
trait TraitWithOneGeneric<P> {
fn method(&self);
}
impl<C, P1, P2> TraitWithOneGeneric<(P1, P2)> for C
where
C: TraitWithOneGeneric<P1> + TraitWithOneGeneric<P2>,
{
fn method(&self) {}
}
// Generic instead of impl trait also doesn't work
fn do_smth<P>(a: &&impl TraitWithOneGeneric<P>) {
a.method(1, 2, 3, 4)
}
I expected to see this happen: Code should throw an error and rustc should exit (or compile)
Instead, this happened: rustc doesn't exit at all and leaks memory infinitely.
Meta
I ran this code either on rust playground or via rustc --crate-type rlib -v lib.rs
rustc --version --verbose:
rustc 1.81.0-nightly (6b0f4b5ec 2024-06-24)
binary: rustc
commit-hash: 6b0f4b5ec3aa707ecaa78230722117324a4ce23c
commit-date: 2024-06-24
host: x86_64-unknown-linux-gnu
release: 1.81.0-nightly
LLVM version: 18.1.7
Same behavior on stable:
rustc --version --verbose:
rustc 1.79.0 (129f3b996 2024-06-10)
binary: rustc
commit-hash: 129f3b9964af4d4a709d1383930ade12dfe7c081
commit-date: 2024-06-10
host: x86_64-unknown-linux-gnu
release: 1.79.0
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 compiling the reproducer with rustc --crate-type rlib -v lib.rs and compare the stable and nightly behavior described in the issue. The work is done when rustc terminates with a diagnostic or successfully compiles without unbounded memory growth.
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
- 30/100