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Remove intermediate vectors from add_bounds #79460

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Merged
merged 1 commit into from
Nov 28, 2020
Merged

Remove intermediate vectors from add_bounds #79460

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19 changes: 5 additions & 14 deletions compiler/rustc_typeck/src/astconv/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -815,34 +815,25 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
ast_bounds: &[hir::GenericBound<'_>],
bounds: &mut Bounds<'tcx>,
) {
let mut trait_bounds = Vec::new();
let mut region_bounds = Vec::new();

let constness = self.default_constness_for_trait_bounds();
for ast_bound in ast_bounds {
match *ast_bound {
hir::GenericBound::Trait(ref b, hir::TraitBoundModifier::None) => {
trait_bounds.push((b, constness))
self.instantiate_poly_trait_ref(b, constness, param_ty, bounds);
}
hir::GenericBound::Trait(ref b, hir::TraitBoundModifier::MaybeConst) => {
trait_bounds.push((b, Constness::NotConst))
self.instantiate_poly_trait_ref(b, Constness::NotConst, param_ty, bounds);
}
hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => {}
hir::GenericBound::LangItemTrait(lang_item, span, hir_id, args) => self
.instantiate_lang_item_trait_ref(
lang_item, span, hir_id, args, param_ty, bounds,
),
hir::GenericBound::Outlives(ref l) => region_bounds.push(l),
hir::GenericBound::Outlives(ref l) => {
bounds.region_bounds.push((self.ast_region_to_region(l, None), l.span))
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The only reason for the design that I can see is that maybe the calls to ast_region_to_region must come after all calls to instantiate_poly_trait_ref are done. The only reason that can happen is if there are inference lifetimes in these bounds. Basically all that can happen is that some ids (created here) are now in a different order, which seems fine to me.

so the TLDR is that I think this change is fine

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Hmm I didn't consider the order of things.

}
}
}

for (bound, constness) in trait_bounds {
let _ = self.instantiate_poly_trait_ref(bound, constness, param_ty, bounds);
}

bounds.region_bounds.extend(
region_bounds.into_iter().map(|r| (self.ast_region_to_region(r, None), r.span)),
);
}

/// Translates a list of bounds from the HIR into the `Bounds` data structure.
Expand Down