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Rollup merge of #103123 - compiler-errors:early-binder-iter, r=cjgillot

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Introduce `subst_iter` and `subst_iter_copied` on `EarlyBinder`

Makes working with bounds lists a bit easier, which I seem to do a lot.

Specifically, means that we don't need to do `.transpose_iter().map(|(pred, _)| *pred)` every time we want to iterate through an `EarlyBinder<&'tcx [(Predicate, Span)]>` (and even then, still have to call `subst` later), which was a very awkward idiom imo.
This commit is contained in:
Matthias Krüger 2022-10-23 08:14:30 +02:00 • committed by GitHub
commit 5290d5e321
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9 changed files with 59 additions and 57 deletions
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16
compiler/rustc_hir_analysis/src/check/compare_method.rs
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@ -664,10 +664,7 @@ impl<'tcx> TypeFolder<'tcx> for ImplTraitInTraitCollector<'_, 'tcx> {
});
self.types.insert(proj.item_def_id, (infer_ty, proj.substs));
// Recurse into bounds
for pred in self.tcx().bound_explicit_item_bounds(proj.item_def_id).transpose_iter() {
let pred_span = pred.0.1;
let pred = pred.map_bound(|(pred, _)| *pred).subst(self.tcx(), proj.substs);
for (pred, pred_span) in self.tcx().bound_explicit_item_bounds(proj.item_def_id).subst_iter_copied(self.tcx(), proj.substs) {
let pred = pred.fold_with(self);
let pred = self.ocx.normalize(
ObligationCause::misc(self.span, self.body_id),
@ -1752,15 +1749,10 @@ pub fn check_type_bounds<'tcx>(
let obligations = tcx
.bound_explicit_item_bounds(trait_ty.def_id)
.transpose_iter()
.map(|e| e.map_bound(|e| *e).transpose_tuple2())
.map(|(bound, span)| {
debug!(?bound);
// this is where opaque type is found
let concrete_ty_bound = bound.subst(tcx, rebased_substs);
.subst_iter_copied(tcx, rebased_substs)
.map(|(concrete_ty_bound, span)| {
debug!("check_type_bounds: concrete_ty_bound = {:?}", concrete_ty_bound);
traits::Obligation::new(mk_cause(span.0), param_env, concrete_ty_bound)
traits::Obligation::new(mk_cause(span), param_env, concrete_ty_bound)
})
.collect();
debug!("check_type_bounds: item_bounds={:?}", obligations);