Release 1.0.54

Support flattened untagged Options in struct fields

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "1.0.53" # remember to update html_root_url
+version = "1.0.54" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "A generic serialization/deserialization framework"
@@ -61,8 +61,3 @@ alloc = ["unstable"]
 # does not preserve identity and may result in multiple copies of the same data.
 # Be sure that this is what you want before enabling this feature.
 rc = []
-
-# Get serde_derive picked up by the Integer 32 playground. Not public API.
-#
-#    http://play.integer32.com/
-playground = ["serde_derive"]

serde/src/de/impls.rs

@@ -529,6 +529,14 @@ where
     {
         T::deserialize(deserializer).map(Some)
     }
+
+    #[doc(hidden)]
+    fn __private_visit_untagged_option<D>(self, deserializer: D) -> Result<Self::Value, ()>
+    where
+        D: Deserializer<'de>,
+    {
+        Ok(T::deserialize(deserializer).ok())
+    }
 }
 
 impl<'de, T> Deserialize<'de> for Option<T>

serde/src/de/mod.rs

@@ -1529,6 +1529,15 @@ pub trait Visitor<'de>: Sized {
         let _ = data;
         Err(Error::invalid_type(Unexpected::Enum, &self))
     }
+
+    // Used when deserializing a flattened Option field. Not public API.
+    #[doc(hidden)]
+    fn __private_visit_untagged_option<D>(self, _: D) -> Result<Self::Value, ()>
+    where
+        D: Deserializer<'de>,
+    {
+        Err(())
+    }
 }
 
 ////////////////////////////////////////////////////////////////////////////////

serde/src/lib.rs

@@ -79,7 +79,7 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.53")]
+#![doc(html_root_url = "https://docs.rs/serde/1.0.54")]
 // Support using Serde without the standard library!
 #![cfg_attr(not(feature = "std"), no_std)]
 // Unstable functionality only if the user asks for it. For tracking and

serde/src/private/de.rs

@@ -2645,10 +2645,7 @@ impl<'a, 'de, E> FlatMapDeserializer<'a, 'de, E>
 where
     E: Error,
 {
-    fn deserialize_other<V>(self, _: V) -> Result<V::Value, E>
+    fn deserialize_other<V>() -> Result<V, E> {
-    where
-        V: Visitor<'de>,
-    {
         Err(Error::custom("can only flatten structs and maps"))
     }
 }
@@ -2657,11 +2654,11 @@ where
 macro_rules! forward_to_deserialize_other {
     ($($func:ident ( $($arg:ty),* ))*) => {
         $(
-            fn $func<V>(self, $(_: $arg,)* visitor: V) -> Result<V::Value, Self::Error>
+            fn $func<V>(self, $(_: $arg,)* _visitor: V) -> Result<V::Value, Self::Error>
             where
                 V: Visitor<'de>,
             {
-                self.deserialize_other(visitor)
+                Self::deserialize_other()
             }
         )*
     }
@@ -2741,6 +2738,16 @@ where
         visitor.visit_newtype_struct(self)
     }
 
+    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: Visitor<'de>,
+    {
+        match visitor.__private_visit_untagged_option(self) {
+            Ok(value) => Ok(value),
+            Err(()) => Self::deserialize_other(),
+        }
+    }
+
     forward_to_deserialize_other! {
         deserialize_bool()
         deserialize_i8()
@@ -2758,7 +2765,6 @@ where
         deserialize_string()
         deserialize_bytes()
         deserialize_byte_buf()
-        deserialize_option()
         deserialize_unit()
         deserialize_unit_struct(&'static str)
         deserialize_seq()

serde/src/private/ser.rs

@@ -1122,14 +1122,14 @@ where
     }
 
     fn serialize_none(self) -> Result<Self::Ok, Self::Error> {
-        Err(self.bad_type(Unsupported::Optional))
+        Ok(())
     }
 
-    fn serialize_some<T: ?Sized>(self, _: &T) -> Result<Self::Ok, Self::Error>
+    fn serialize_some<T: ?Sized>(self, value: &T) -> Result<Self::Ok, Self::Error>
     where
         T: Serialize,
     {
-        Err(self.bad_type(Unsupported::Optional))
+        value.serialize(self)
     }
 
     fn serialize_unit(self) -> Result<Self::Ok, Self::Error> {

serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.53" # remember to update html_root_url
+version = "1.0.54" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"

serde_derive/src/de.rs

@@ -864,7 +864,9 @@ fn deserialize_struct(
         None => format!("struct {}", params.type_name()),
     };
 
-    let visit_seq = Stmts(deserialize_seq(&type_path, params, fields, true, cattrs, &expecting));
+    let visit_seq = Stmts(deserialize_seq(
+        &type_path, params, fields, true, cattrs, &expecting,
+    ));
 
     let (field_visitor, fields_stmt, visit_map) = if cattrs.has_flatten() {
         deserialize_struct_as_map_visitor(&type_path, params, fields, cattrs)

serde_derive/src/lib.rs

@@ -22,7 +22,7 @@
 //!
 //! [https://serde.rs/derive.html]: https://serde.rs/derive.html
 
-#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.53")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.54")]
 #![cfg_attr(feature = "cargo-clippy", deny(clippy, clippy_pedantic))]
 // Whitelisted clippy lints
 #![cfg_attr(

serde_derive/src/ser.rs

@@ -256,7 +256,10 @@ fn serialize_tuple_struct(
         .map(|(i, field)| match field.attrs.skip_serializing_if() {
             None => quote!(1),
             Some(path) => {
-                let index = syn::Index { index: i as u32, span: Span::call_site() };
+                let index = syn::Index {
+                    index: i as u32,
+                    span: Span::call_site(),
+                };
                 let field_expr = get_member(params, field, &Member::Unnamed(index));
                 quote!(if #path(#field_expr) { 0 } else { 1 })
             }

serde_test/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_test"
-version = "1.0.53" # remember to update html_root_url
+version = "1.0.54" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "Token De/Serializer for testing De/Serialize implementations"

serde_test/src/lib.rs

@@ -161,7 +161,7 @@
 //! # }
 //! ```
 
-#![doc(html_root_url = "https://docs.rs/serde_test/1.0.53")]
+#![doc(html_root_url = "https://docs.rs/serde_test/1.0.54")]
 #![cfg_attr(feature = "cargo-clippy", deny(clippy, clippy_pedantic))]
 // Whitelisted clippy lints
 #![cfg_attr(feature = "cargo-clippy", allow(float_cmp))]

test_suite/tests/test_annotations.rs

@@ -2095,3 +2095,84 @@ fn test_flatten_untagged_enum() {
         ],
     );
 }
+
+#[test]
+fn test_flatten_option() {
+    #[derive(Serialize, Deserialize, PartialEq, Debug)]
+    struct Outer {
+        #[serde(flatten)]
+        inner1: Option<Inner1>,
+        #[serde(flatten)]
+        inner2: Option<Inner2>,
+    }
+
+    #[derive(Serialize, Deserialize, PartialEq, Debug)]
+    struct Inner1 {
+        inner1: i32,
+    }
+
+    #[derive(Serialize, Deserialize, PartialEq, Debug)]
+    struct Inner2 {
+        inner2: i32,
+    }
+
+    assert_tokens(
+        &Outer {
+            inner1: Some(Inner1 {
+                inner1: 1,
+            }),
+            inner2: Some(Inner2 {
+                inner2: 2,
+            }),
+        },
+        &[
+            Token::Map { len: None },
+            Token::Str("inner1"),
+            Token::I32(1),
+            Token::Str("inner2"),
+            Token::I32(2),
+            Token::MapEnd,
+        ],
+    );
+
+    assert_tokens(
+        &Outer {
+            inner1: Some(Inner1 {
+                inner1: 1,
+            }),
+            inner2: None,
+        },
+        &[
+            Token::Map { len: None },
+            Token::Str("inner1"),
+            Token::I32(1),
+            Token::MapEnd,
+        ],
+    );
+
+    assert_tokens(
+        &Outer {
+            inner1: None,
+            inner2: Some(Inner2 {
+                inner2: 2,
+            }),
+        },
+        &[
+            Token::Map { len: None },
+            Token::Str("inner2"),
+            Token::I32(2),
+            Token::MapEnd,
+        ],
+    );
+
+    assert_tokens(
+        &Outer {
+            inner1: None,
+            inner2: None,
+        },
+        &[
+            Token::Map { len: None },
+            Token::MapEnd,
+        ],
+    );
+}