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Rollup merge of #77754 - bugadani:find_map_relevant_impl, r=matthewjasper

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Add TraitDef::find_map_relevant_impl

This PR adds a method to `TraitDef`. While `for_each_relevant_impl` covers the general use case, sometimes it's not necessary to scan through all the relevant implementations, so this PR introduces a new method, `find_map_relevant_impl`. I've also replaced the `for_each_relevant_impl` calls where possible.

I'm hoping for a tiny bit of efficiency gain here and there.
This commit is contained in:
Yuki Okushi 2020-10-11 03:19:14 +09:00 • committed by GitHub
commit 8752b43900
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5 changed files with 38 additions and 27 deletions
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16
src/librustdoc/passes/collect_intra_doc_links.rs
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@ -650,14 +650,9 @@ fn traits_implemented_by(cx: &DocContext<'_>, type_: DefId, module: DefId) -> Fx
let ty = cx.tcx.type_of(type_);
let iter = in_scope_traits.iter().flat_map(|&trait_| {
trace!("considering explicit impl for trait {:?}", trait_);
let mut saw_impl = false;
// Look at each trait implementation to see if it's an impl for `did`
cx.tcx.for_each_relevant_impl(trait_, ty, |impl_| {
// FIXME: this is inefficient, find a way to short-circuit for_each_* so this doesn't take as long
if saw_impl {
return;
}
// Look at each trait implementation to see if it's an impl for `did`
cx.tcx.find_map_relevant_impl(trait_, ty, |impl_| {
let trait_ref = cx.tcx.impl_trait_ref(impl_).expect("this is not an inherent impl");
// Check if these are the same type.
let impl_type = trait_ref.self_ty();
@ -668,7 +663,7 @@ fn traits_implemented_by(cx: &DocContext<'_>, type_: DefId, module: DefId) -> Fx
type_
);
// Fast path: if this is a primitive simple `==` will work
saw_impl = impl_type == ty
let saw_impl = impl_type == ty
|| match impl_type.kind() {
// Check if these are the same def_id
ty::Adt(def, _) => {
@ -678,8 +673,9 @@ fn traits_implemented_by(cx: &DocContext<'_>, type_: DefId, module: DefId) -> Fx
ty::Foreign(def_id) => *def_id == type_,
_ => false,
};
});
if saw_impl { Some(trait_) } else { None }
if saw_impl { Some(trait_) } else { None }
})
});
iter.collect()
}