Remove #[serde(repr = "map")]

serde_derive/src/de.rs

@@ -770,10 +770,7 @@ fn deserialize_struct(
     untagged: &Untagged,
 ) -> Fragment {
     let is_enum = variant_ident.is_some();
-    let as_map = deserializer.is_none() && !is_enum && match cattrs.repr() {
-        attr::ContainerRepr::Struct | attr::ContainerRepr::Auto => false,
-        attr::ContainerRepr::Map => true,
-    };
+    let as_map = deserializer.is_none() && !is_enum && cattrs.has_flatten();
 
     let this = &params.this;
     let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
@@ -896,10 +893,7 @@ fn deserialize_struct_in_place(
     deserializer: Option<Tokens>,
 ) -> Option<Fragment> {
     let is_enum = variant_ident.is_some();
-    let as_map = deserializer.is_none() && !is_enum && match cattrs.repr() {
-        attr::ContainerRepr::Struct | attr::ContainerRepr::Auto => false,
-        attr::ContainerRepr::Map => true,
-    };
+    let as_map = deserializer.is_none() && !is_enum && cattrs.has_flatten();
 
     // for now we do not support in_place deserialization for structs that
     // are represented as map.

serde_derive/src/ser.rs

@@ -245,9 +245,10 @@ fn serialize_tuple_struct(
 fn serialize_struct(params: &Parameters, fields: &[Field], cattrs: &attr::Container) -> Fragment {
     assert!(fields.len() as u64 <= u64::from(u32::MAX));
 
-    match cattrs.repr() {
-        attr::ContainerRepr::Struct | attr::ContainerRepr::Auto => serialize_struct_as_struct(params, fields, cattrs),
-        attr::ContainerRepr::Map => serialize_struct_as_map(params, fields, cattrs),
+    if cattrs.has_flatten() {
+        serialize_struct_as_map(params, fields, cattrs)
+    } else {
+        serialize_struct_as_struct(params, fields, cattrs)
     }
 }
 

serde_derive_internals/src/ast.rs

@@ -79,12 +79,6 @@ impl<'a> Container<'a> {
             },
         }
 
-        if has_flatten && attrs.repr() != attr::ContainerRepr::Map {
-            cx.error(format!("#[serde(flatten)] requires \
-                              #[serde(repr = \"map\")] on the container, but \
-                              found #[serde(repr = \"{}\")]", attrs.repr()));
-        }
-
         if has_flatten {
             attrs.mark_has_flatten();
         }

serde_derive_internals/src/attr.rs

@@ -15,7 +15,6 @@ use syn::punctuated::Punctuated;
 use syn::synom::{Synom, ParseError};
 use std::collections::BTreeSet;
 use std::str::FromStr;
-use std::fmt;
 use proc_macro2::{Span, TokenStream, TokenNode, TokenTree};
 
 // This module handles parsing of `#[serde(...)]` attributes. The entrypoints
@@ -103,35 +102,6 @@ impl Name {
     }
 }
 
-#[derive(Debug, PartialEq, Eq, Copy, Clone)]
-pub enum ContainerRepr {
-    Auto,
-    Struct,
-    Map,
-}
-
-impl fmt::Display for ContainerRepr {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", match *self {
-            ContainerRepr::Auto => "auto",
-            ContainerRepr::Struct => "struct",
-            ContainerRepr::Map => "map",
-        })
-    }
-}
-
-impl FromStr for ContainerRepr {
-    type Err = ();
-    fn from_str(s: &str) -> Result<ContainerRepr, ()> {
-        match s {
-            "auto" => Ok(ContainerRepr::Auto),
-            "struct" => Ok(ContainerRepr::Struct),
-            "map" => Ok(ContainerRepr::Map),
-            _ => Err(()),
-        }
-    }
-}
-
 /// Represents container (e.g. struct) attribute information
 pub struct Container {
     name: Name,
@@ -145,7 +115,6 @@ pub struct Container {
     type_into: Option<syn::Type>,
     remote: Option<syn::Path>,
     identifier: Identifier,
-    repr: ContainerRepr,
     has_flatten: bool,
 }
 
@@ -224,7 +193,6 @@ impl Container {
         let mut remote = Attr::none(cx, "remote");
         let mut field_identifier = BoolAttr::none(cx, "field_identifier");
         let mut variant_identifier = BoolAttr::none(cx, "variant_identifier");
-        let mut repr = Attr::none(cx, "repr");
 
         for meta_items in item.attrs.iter().filter_map(get_serde_meta_items) {
             for meta_item in meta_items {
@@ -264,16 +232,6 @@ impl Container {
                         deny_unknown_fields.set_true();
                     }
 
-                    // Parse `#[serde(repr = "foo")]`
-                    Meta(NameValue(ref m)) if m.ident == "repr" => {
-                        if let Ok(s) = get_lit_str(cx, m.ident.as_ref(), m.ident.as_ref(), &m.lit) {
-                            match ContainerRepr::from_str(&s.value()) {
-                                Ok(value) => repr.set(value),
-                                Err(()) => cx.error(format!("unknown value for #[serde(repr = {})]", s.value()))
-                            }
-                        }
-                    }
-
                     // Parse `#[serde(default)]`
                     Meta(Word(word)) if word == "default" => match item.data {
                         syn::Data::Struct(syn::DataStruct { fields: syn::Fields::Named(_), .. }) => {
@@ -417,7 +375,6 @@ impl Container {
             type_into: type_into.get(),
             remote: remote.get(),
             identifier: decide_identifier(cx, item, &field_identifier, &variant_identifier),
-            repr: repr.get().unwrap_or(ContainerRepr::Auto),
             has_flatten: false,
         }
     }
@@ -466,10 +423,6 @@ impl Container {
         self.identifier
     }
 
-    pub fn repr(&self) -> ContainerRepr {
-        self.repr
-    }
-
     pub fn has_flatten(&self) -> bool {
         self.has_flatten
     }

test_suite/tests/test_annotations.rs

@@ -96,7 +96,6 @@ where
 }
 
 #[derive(Debug, PartialEq, Serialize, Deserialize)]
-#[serde(repr = "map")]
 struct CollectOther {
     a: u32,
     b: u32,
@@ -105,7 +104,6 @@ struct CollectOther {
 }
 
 #[derive(Debug, PartialEq, Serialize, Deserialize)]
-#[serde(repr = "map")]
 struct FlattenStructEnumWrapper {
     #[serde(flatten)]
     data: FlattenStructEnum,
@@ -123,7 +121,6 @@ enum FlattenStructEnum {
 }
 
 #[derive(Debug, PartialEq, Serialize, Deserialize)]
-#[serde(repr = "map")]
 struct FlattenStructTagContentEnumWrapper {
     outer: u32,
     #[serde(flatten)]
@@ -1497,7 +1494,7 @@ fn test_flatten_struct_tag_content_enum_newtype() {
 #[test]
 fn test_unknown_field_in_flatten() {
     #[derive(Debug, PartialEq, Serialize, Deserialize)]
-    #[serde(repr = "map", deny_unknown_fields)]
+    #[serde(deny_unknown_fields)]
     struct Outer {
         dummy: String,
         #[serde(flatten)]