From b729815fc72bc08544c6d630cb0dacadfc6ccef3 Mon Sep 17 00:00:00 2001 From: lcnr Date: Tue, 6 Apr 2021 17:06:44 +0200 Subject: [PATCH] use a `SmallVec` in `impl_or_trait_item` --- compiler/rustc_typeck/src/check/method/probe.rs | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/compiler/rustc_typeck/src/check/method/probe.rs b/compiler/rustc_typeck/src/check/method/probe.rs index d83b74f4ce9..15342235d48 100644 --- a/compiler/rustc_typeck/src/check/method/probe.rs +++ b/compiler/rustc_typeck/src/check/method/probe.rs @@ -1768,7 +1768,9 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> { /// Finds the method with the appropriate name (or return type, as the case may be). If /// `allow_similar_names` is set, find methods with close-matching names. - fn impl_or_trait_item(&self, def_id: DefId) -> Vec { + // The length of the returned iterator is nearly always 0 or 1 and this + // method is fairly hot. + fn impl_or_trait_item(&self, def_id: DefId) -> SmallVec<[ty::AssocItem; 1]> { if let Some(name) = self.method_name { if self.allow_similar_names { let max_dist = max(name.as_str().len(), 3) / 3; @@ -1784,7 +1786,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> { } else { self.fcx .associated_item(def_id, name, Namespace::ValueNS) - .map_or_else(Vec::new, |x| vec![x]) + .map_or_else(SmallVec::new, |x| SmallVec::from_buf([x])) } } else { self.tcx.associated_items(def_id).in_definition_order().copied().collect()