From 6e2c385fa55d223e3d9dd22ff126f81b4903e05b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?A=CC=81rpa=CC=81d=20Goretity?= <h2co3@h2co3.org>
Date: Wed, 6 Nov 2019 17:31:27 +0100
Subject: [PATCH] Allow untagged unit variants to deserialize from
 `Visitor::visit_none()`

---
 serde/src/private/de.rs     | 7 +++++++
 test_suite/tests/test_de.rs | 9 +++++++++
 2 files changed, 16 insertions(+)

diff --git a/serde/src/private/de.rs b/serde/src/private/de.rs
index ffa5012d..1c7fda3a 100644
--- a/serde/src/private/de.rs
+++ b/serde/src/private/de.rs
@@ -2510,6 +2510,13 @@ mod content {
         {
             Ok(())
         }
+
+        fn visit_none<E>(self) -> Result<(), E>
+        where
+            E: de::Error,
+        {
+            Ok(())
+        }
     }
 }
 
diff --git a/test_suite/tests/test_de.rs b/test_suite/tests/test_de.rs
index 025d87b0..a1da9509 100644
--- a/test_suite/tests/test_de.rs
+++ b/test_suite/tests/test_de.rs
@@ -137,6 +137,12 @@ enum EnumOther {
     Other,
 }
 
+#[derive(PartialEq, Debug, Deserialize)]
+#[serde(untagged)]
+enum EnumUntaggedUnit {
+    Unit,
+}
+
 #[derive(PartialEq, Debug)]
 struct IgnoredAny;
 
@@ -788,6 +794,9 @@ declare_tests! {
             Token::Unit,
         ],
     }
+    test_enum_untagged_unit_from_none {
+        UntaggedUnit::Unit => &[Token::None],
+    }
     test_box {
         Box::new(0i32) => &[Token::I32(0)],
     }