mirror
/
rustc-dev-guide
mirror of https://github.com/rust-lang/rustc-dev-guide.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

update section even more (#2156)

This commit is contained in:
lcnr 2024-12-05 13:30:36 +01:00 committed by GitHub
parent fccf752c1c
commit 1f851c0fc5
1 changed files with 9 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
src/borrow_check/region_inference/closure_constraints.md
View File

@ -11,7 +11,15 @@ they hold, we report an error.
## How this is implemented
While borrow-checking a closure inside of `RegionInferenceContext::solve` we call `check_type_tests` with a list of `outlives_requirements` to propagate to the caller. This happens after computing the outlives graph, which is now immutable.
While borrow-checking a closure inside of `RegionInferenceContext::solve` we separately try to propagate type-outlives and region-outlives constraints to the parent if we're unable to prove them locally.
### Region-outlive constraints
If we fail to prove a region-outlives constraint, we try to propagate it in `fn try_propagate_universal_region_error`.
### Type-outlive constraints
Type-outlives constraints are proven in `check_type_tests`. This happens after computing the outlives graph, which is now immutable.
For all type tests we fail to prove via `fn eval_verify_bound` inside of the closure we call `try_promote_type_test`. A `TypeTest` represents a type-outlives bound `generic_kind: lower_bound` together with a `verify_bound`. If the `VerifyBound` holds for the `lower_bound`, the constraint is satisfied. `try_promote_type_test` does not care about the ` verify_bound`.