From f4c03fd8473c2b5a254789abcb712c90b558f92d Mon Sep 17 00:00:00 2001
From: ljedrz <ljedrz@gmail.com>
Date: Wed, 31 Oct 2018 16:58:51 +0100
Subject: syntax: improve a few allocations

---
 src/libsyntax/ext/expand.rs | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'src/libsyntax')

diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 33b651e1b38..37e7b44694f 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -387,6 +387,8 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                         add_derived_markers(&mut self.cx, item.span(), &traits, item.clone());
                     let derives = derives.entry(invoc.expansion_data.mark).or_default();
 
+                    derives.reserve(traits.len());
+                    invocations.reserve(traits.len());
                     for path in &traits {
                         let mark = Mark::fresh(self.cx.current_expansion.mark);
                         derives.push(mark);
-- 
cgit 1.4.1-3-g733a5