bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Fix comment in poly_project_and_unify_type

Browse source
This commit is contained in:
Michael Goulet 2022-05-30 14:36:12 -07:00
parent 4a8d2e3856
commit c00d9bf324
1 changed files with 14 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

28
compiler/rustc_trait_selection/src/traits/project.rs
View file

@ -145,15 +145,28 @@ impl<'tcx> ProjectionCandidateSet<'tcx> {
}
}
/// Takes the place of a
/// States returned from `poly_project_and_unify_type`. Takes the place
/// of the old return type, which was:
/// ```ignore (not-rust)
/// Result<
/// Result<Option<Vec<PredicateObligation<'tcx>>>, InProgress>,
/// MismatchedProjectionTypes<'tcx>,
/// >
/// ```
pub(super) enum ProjectAndUnifyResult<'tcx> {
/// The projection bound holds subject to the given obligations. If the
/// projection cannot be normalized because the required trait bound does
/// not hold, this is returned, with `obligations` being a predicate that
/// cannot be proven.
Holds(Vec<PredicateObligation<'tcx>>),
/// The projection cannot be normalized due to ambiguity. Resolving some
/// inference variables in the projection may fix this.
FailedNormalization,
/// The project cannot be normalized because `poly_project_and_unify_type`
/// is called recursively while normalizing the same projection.
Recursive,
// the projection can be normalized, but is not equal to the expected type.
// Returns the type error that arose from the mismatch.
MismatchedProjectionTypes(MismatchedProjectionTypes<'tcx>),
}
@ -163,19 +176,6 @@ pub(super) enum ProjectAndUnifyResult<'tcx> {
/// ```
/// If successful, this may result in additional obligations. Also returns
/// the projection cache key used to track these additional obligations.
///
/// ## Returns
///
/// - `Err(_)`: the projection can be normalized, but is not equal to the
/// expected type.
/// - `Ok(Err(InProgress))`: this is called recursively while normalizing
/// the same projection.
/// - `Ok(Ok(None))`: The projection cannot be normalized due to ambiguity
/// (resolving some inference variables in the projection may fix this).
/// - `Ok(Ok(Some(obligations)))`: The projection bound holds subject to
/// the given obligations. If the projection cannot be normalized because
/// the required trait bound doesn't hold this returned with `obligations`
/// being a predicate that cannot be proven.
#[instrument(level = "debug", skip(selcx))]
pub(super) fn poly_project_and_unify_type<'cx, 'tcx>(
selcx: &mut SelectionContext<'cx, 'tcx>,