bjoernager/rust
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Simplify object_region_bounds

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This commit is contained in:
Michael Goulet 2024-11-25 17:38:28 +00:00
parent 7db7489f9b
commit d3867174c0
2 changed files with 7 additions and 30 deletions
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36
compiler/rustc_trait_selection/src/traits/wf.rs
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@ -963,30 +963,7 @@ impl<'a, 'tcx> TypeVisitor<TyCtxt<'tcx>> for WfPredicates<'a, 'tcx> {
/// bounds that must hold on the elided self type. These are derived
/// from the declarations of `SomeTrait`, `Send`, and friends -- if
/// they declare `trait SomeTrait : 'static`, for example, then
/// `'static` would appear in the list. The hard work is done by
/// `infer::required_region_bounds`, see that for more information.
pub fn object_region_bounds<'tcx>(
tcx: TyCtxt<'tcx>,
existential_predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
) -> Vec<ty::Region<'tcx>> {
let predicates = existential_predicates.iter().filter_map(|predicate| {
if let ty::ExistentialPredicate::Projection(_) = predicate.skip_binder() {
None
} else {
Some(predicate.with_self_ty(tcx, tcx.types.trait_object_dummy_self))
}
});
required_region_bounds(tcx, tcx.types.trait_object_dummy_self, predicates)
}
/// Given a set of predicates that apply to an object type, returns
/// the region bounds that the (erased) `Self` type must
/// outlive. Precisely *because* the `Self` type is erased, the
/// parameter `erased_self_ty` must be supplied to indicate what type
/// has been used to represent `Self` in the predicates
/// themselves. This should really be a unique type; `FreshTy(0)` is a
/// popular choice.
/// `'static` would appear in the list.
///
/// N.B., in some cases, particularly around higher-ranked bounds,
/// this function returns a kind of conservative approximation.
@ -996,13 +973,14 @@ pub fn object_region_bounds<'tcx>(
///
/// Requires that trait definitions have been processed so that we can
/// elaborate predicates and walk supertraits.
#[instrument(skip(tcx, predicates), level = "debug", ret)]
pub(crate) fn required_region_bounds<'tcx>(
pub fn object_region_bounds<'tcx>(
tcx: TyCtxt<'tcx>,
erased_self_ty: Ty<'tcx>,
predicates: impl Iterator<Item = ty::Clause<'tcx>>,
existential_predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
) -> Vec<ty::Region<'tcx>> {
assert!(!erased_self_ty.has_escaping_bound_vars());
let erased_self_ty = tcx.types.trait_object_dummy_self;
let predicates =
existential_predicates.iter().map(|predicate| predicate.with_self_ty(tcx, erased_self_ty));
traits::elaborate(tcx, predicates)
.filter_map(|pred| {