From b82d76c8a14bcdb166d453604fde6903bb52d80e Mon Sep 17 00:00:00 2001
From: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>
Date: Tue, 6 Oct 2015 01:47:35 +0300
Subject: [PATCH] Add comment for the use of Ident in hash map in mtwt

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

diff --git a/src/libsyntax/ext/mtwt.rs b/src/libsyntax/ext/mtwt.rs
index bb58152e4ef..7ac0e8c64c2 100644
--- a/src/libsyntax/ext/mtwt.rs
+++ b/src/libsyntax/ext/mtwt.rs
@@ -35,6 +35,8 @@ use std::collections::HashMap;
 pub struct SCTable {
     table: RefCell<Vec<SyntaxContext_>>,
     mark_memo: RefCell<HashMap<(SyntaxContext,Mrk),SyntaxContext>>,
+    // The pair (Name,SyntaxContext) is actually one Ident, but it needs to be hashed and
+    // compared as pair (name, ctxt) and not as an Ident
     rename_memo: RefCell<HashMap<(SyntaxContext,(Name,SyntaxContext),Name),SyntaxContext>>,
 }