Skip to content

Do not eagerly fold consts in normalize_param_env_or_error if new solver #141332

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
May 21, 2025

Conversation

compiler-errors
Copy link
Member

Fixes rust-lang/trait-system-refactor-initiative#213

Given:

trait Trait: Deref<Target = [u8; { 1 + 1 }]> {}

when elaborating param env for Trait, we have Self: Trait, Self: Deref<Target = [u8; {anon const}]>.

Before this PR, we would fold the anon consts away before elaborating. However, we end up getting another un-folded copy of the anon const from elaborating Self: Trait. This leads to normalization ambiguity.

r? lcnr

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. WG-trait-system-refactor The Rustc Trait System Refactor Initiative (-Znext-solver) labels May 21, 2025
@lcnr
Copy link
Contributor

lcnr commented May 21, 2025

@bors r+ rollup

@bors
Copy link
Collaborator

bors commented May 21, 2025

📌 Commit 44a2af3 has been approved by lcnr

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 21, 2025
bors added a commit to rust-lang-ci/rust that referenced this pull request May 21, 2025
…iaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#141267 (only resolve top-level guard patterns' guards once)
 - rust-lang#141280 (Use Docker cache from the current repository)
 - rust-lang#141296 (Async drop fix for 'broken mir, place has deref as later projection')
 - rust-lang#141328 (When AsyncDrop impl is empty, sync drop generated in elaborator)
 - rust-lang#141332 (Do not eagerly fold consts in `normalize_param_env_or_error` if new solver)
 - rust-lang#141333 (Use `DeepRejectCtxt` in `assemble_inherent_candidates_from_param`)
 - rust-lang#141334 (eagerly check nested obligations when coercing fndefs)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 6606fd9 into rust-lang:master May 21, 2025
6 checks passed
@rustbot rustbot added this to the 1.89.0 milestone May 21, 2025
rust-timer added a commit to rust-lang-ci/rust that referenced this pull request May 21, 2025
Rollup merge of rust-lang#141332 - compiler-errors:no-fold-const, r=lcnr

Do not eagerly fold consts in `normalize_param_env_or_error` if new solver

Fixes rust-lang/trait-system-refactor-initiative#213

Given:

```
trait Trait: Deref<Target = [u8; { 1 + 1 }]> {}
```

when elaborating param env for `Trait`, we have `Self: Trait`, `Self: Deref<Target = [u8; {anon const}]>`.

Before this PR, we would fold the anon consts away *before* elaborating. However, we end up getting another *un-folded* copy of the anon const from elaborating `Self: Trait`. This leads to normalization ambiguity.

r? lcnr
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. WG-trait-system-refactor The Rustc Trait System Refactor Initiative (-Znext-solver)
Projects
None yet
Development

Successfully merging this pull request may close these issues.

Folding anon consts in param_env query can lead to ambiguity
4 participants