From 780a461d926a05c0d18847a24b1bec596e4f399d Mon Sep 17 00:00:00 2001
From: Mingun <Alexander_Sergey@mail.ru>
Date: Mon, 26 Oct 2020 22:06:00 +0500
Subject: [PATCH 1/3] Generate one deserializer rather than in each arm

---
 serde_derive/src/de.rs | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/serde_derive/src/de.rs b/serde_derive/src/de.rs
index 2dfe87ef0..2e86fd867 100644
--- a/serde_derive/src/de.rs
+++ b/serde_derive/src/de.rs
@@ -1356,9 +1356,7 @@ fn deserialize_internally_tagged_enum(
                 params,
                 variant,
                 cattrs,
-                quote! {
-                    _serde::__private::de::ContentDeserializer::<__D::Error>::new(__tagged.content)
-                },
+                quote!(__deserializer),
             ));
 
             quote! {
@@ -1377,6 +1375,7 @@ fn deserialize_internally_tagged_enum(
         let __tagged = try!(_serde::Deserializer::deserialize_any(
             __deserializer,
             _serde::__private::de::TaggedContentVisitor::<__Field>::new(#tag, #expecting)));
+        let __deserializer = _serde::__private::de::ContentDeserializer::<__D::Error>::new(__tagged.content);
 
         match __tagged.tag {
             #(#variant_arms)*

From b61ec84886b0689d571ff7bfdbbca0cf74012b1f Mon Sep 17 00:00:00 2001
From: Mingun <Alexander_Sergey@mail.ru>
Date: Sun, 2 Oct 2022 21:12:02 +0500
Subject: [PATCH 2/3] Remove implementation of `DeserializeSeed` for
 `TaggedContentVisitor`

It is not used anywhere
---
 serde/src/private/de.rs | 16 ----------------
 1 file changed, 16 deletions(-)

diff --git a/serde/src/private/de.rs b/serde/src/private/de.rs
index 1396b1031..49dec18f8 100644
--- a/serde/src/private/de.rs
+++ b/serde/src/private/de.rs
@@ -821,22 +821,6 @@ mod content {
         }
     }
 
-    impl<'de, T> DeserializeSeed<'de> for TaggedContentVisitor<'de, T>
-    where
-        T: Deserialize<'de>,
-    {
-        type Value = TaggedContent<'de, T>;
-
-        fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
-        where
-            D: Deserializer<'de>,
-        {
-            // Internally tagged enums are only supported in self-describing
-            // formats.
-            deserializer.deserialize_any(self)
-        }
-    }
-
     impl<'de, T> Visitor<'de> for TaggedContentVisitor<'de, T>
     where
         T: Deserialize<'de>,

From 3783a30ae7b02ab5870615af86f850dd0953df69 Mon Sep 17 00:00:00 2001
From: Mingun <Alexander_Sergey@mail.ru>
Date: Sun, 2 Oct 2022 19:34:33 +0500
Subject: [PATCH 3/3] Remove `TaggedContent`, replace it by a tuple

That type does not give any benefits so we can avoid that hidden public but no-API struct
---
 serde/src/private/de.rs | 26 +++++++-------------------
 serde_derive/src/de.rs  |  6 +++---
 2 files changed, 10 insertions(+), 22 deletions(-)

diff --git a/serde/src/private/de.rs b/serde/src/private/de.rs
index 49dec18f8..78cdef672 100644
--- a/serde/src/private/de.rs
+++ b/serde/src/private/de.rs
@@ -797,19 +797,13 @@ mod content {
     /// Used by generated code to deserialize an internally tagged enum.
     ///
     /// Not public API.
-    pub struct TaggedContent<'de, T> {
-        pub tag: T,
-        pub content: Content<'de>,
-    }
-
-    /// Not public API.
-    pub struct TaggedContentVisitor<'de, T> {
+    pub struct TaggedContentVisitor<T> {
         tag_name: &'static str,
         expecting: &'static str,
-        value: PhantomData<TaggedContent<'de, T>>,
+        value: PhantomData<T>,
     }
 
-    impl<'de, T> TaggedContentVisitor<'de, T> {
+    impl<T> TaggedContentVisitor<T> {
         /// Visitor for the content of an internally tagged enum with the given
         /// tag name.
         pub fn new(name: &'static str, expecting: &'static str) -> Self {
@@ -821,11 +815,11 @@ mod content {
         }
     }
 
-    impl<'de, T> Visitor<'de> for TaggedContentVisitor<'de, T>
+    impl<'de, T> Visitor<'de> for TaggedContentVisitor<T>
     where
         T: Deserialize<'de>,
     {
-        type Value = TaggedContent<'de, T>;
+        type Value = (T, Content<'de>);
 
         fn expecting(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
             fmt.write_str(self.expecting)
@@ -842,10 +836,7 @@ mod content {
                 }
             };
             let rest = de::value::SeqAccessDeserializer::new(seq);
-            Ok(TaggedContent {
-                tag,
-                content: try!(Content::deserialize(rest)),
-            })
+            Ok((tag, try!(Content::deserialize(rest))))
         }
 
         fn visit_map<M>(self, mut map: M) -> Result<Self::Value, M::Error>
@@ -870,10 +861,7 @@ mod content {
             }
             match tag {
                 None => Err(de::Error::missing_field(self.tag_name)),
-                Some(tag) => Ok(TaggedContent {
-                    tag,
-                    content: Content::Map(vec),
-                }),
+                Some(tag) => Ok((tag, Content::Map(vec))),
             }
         }
     }
diff --git a/serde_derive/src/de.rs b/serde_derive/src/de.rs
index 2e86fd867..1366fb769 100644
--- a/serde_derive/src/de.rs
+++ b/serde_derive/src/de.rs
@@ -1372,12 +1372,12 @@ fn deserialize_internally_tagged_enum(
 
         #variants_stmt
 
-        let __tagged = try!(_serde::Deserializer::deserialize_any(
+        let (__tag, __content) = try!(_serde::Deserializer::deserialize_any(
             __deserializer,
             _serde::__private::de::TaggedContentVisitor::<__Field>::new(#tag, #expecting)));
-        let __deserializer = _serde::__private::de::ContentDeserializer::<__D::Error>::new(__tagged.content);
+        let __deserializer = _serde::__private::de::ContentDeserializer::<__D::Error>::new(__content);
 
-        match __tagged.tag {
+        match __tag {
             #(#variant_arms)*
         }
     }