From 2af11a5a714c9cb478e550d757b9eef113f5ddfa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Asbj=C3=B8rn=20Gaarde?= <asbjorn_gaarde@hotmail.com>
Date: Fri, 8 Nov 2019 16:44:58 +0100
Subject: [PATCH] Parse TypeTuple with one element requires trailing comma

---
 src/ty.rs | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/ty.rs b/src/ty.rs
index 1e5b51f3df..b2e086becf 100644
--- a/src/ty.rs
+++ b/src/ty.rs
@@ -784,9 +784,27 @@ pub mod parsing {
     impl Parse for TypeTuple {
         fn parse(input: ParseStream) -> Result<Self> {
             let content;
+            let paren_token = parenthesized!(content in input);
+
+            if content.is_empty() {
+                return Ok(TypeTuple {
+                    paren_token,
+                    elems: Punctuated::new(),
+                });
+            }
+
+            let first: Type = content.parse()?;
             Ok(TypeTuple {
-                paren_token: parenthesized!(content in input),
-                elems: content.parse_terminated(Type::parse)?,
+                paren_token,
+                elems: {
+                    let mut elems = Punctuated::new();
+                    elems.push_value(first);
+                    elems.push_punct(content.parse()?);
+                    let rest: Punctuated<Type, Token![,]> =
+                        content.parse_terminated(Parse::parse)?;
+                    elems.extend(rest);
+                    elems
+                },
             })
         }
     }