Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3142 insertions, 0 deletions

diff --git a/third_party/rust/serde_derive/src/de.rs b/third_party/rust/serde_derive/src/de.rs
new file mode 100644
index 0000000000..a703adaf7d
--- /dev/null
+++ b/third_party/rust/serde_derive/src/de.rs
@@ -0,0 +1,3142 @@
+use proc_macro2::{Literal, Span, TokenStream};
+use quote::ToTokens;
+use syn::punctuated::Punctuated;
+use syn::spanned::Spanned;
+use syn::{self, Ident, Index, Member};
+
+use bound;
+use dummy;
+use fragment::{Expr, Fragment, Match, Stmts};
+use internals::ast::{Container, Data, Field, Style, Variant};
+use internals::{attr, replace_receiver, ungroup, Ctxt, Derive};
+use pretend;
+use this;
+
+use std::collections::BTreeSet;
+use std::ptr;
+
+pub fn expand_derive_deserialize(
+    input: &mut syn::DeriveInput,
+) -> Result<TokenStream, Vec<syn::Error>> {
+    replace_receiver(input);
+
+    let ctxt = Ctxt::new();
+    let cont = match Container::from_ast(&ctxt, input, Derive::Deserialize) {
+        Some(cont) => cont,
+        None => return Err(ctxt.check().unwrap_err()),
+    };
+    precondition(&ctxt, &cont);
+    ctxt.check()?;
+
+    let ident = &cont.ident;
+    let params = Parameters::new(&cont);
+    let (de_impl_generics, _, ty_generics, where_clause) = split_with_de_lifetime(&params);
+    let body = Stmts(deserialize_body(&cont, &params));
+    let delife = params.borrowed.de_lifetime();
+    let serde = cont.attrs.serde_path();
+
+    let impl_block = if let Some(remote) = cont.attrs.remote() {
+        let vis = &input.vis;
+        let used = pretend::pretend_used(&cont, params.is_packed);
+        quote! {
+            impl #de_impl_generics #ident #ty_generics #where_clause {
+                #vis fn deserialize<__D>(__deserializer: __D) -> #serde::__private::Result<#remote #ty_generics, __D::Error>
+                where
+                    __D: #serde::Deserializer<#delife>,
+                {
+                    #used
+                    #body
+                }
+            }
+        }
+    } else {
+        let fn_deserialize_in_place = deserialize_in_place_body(&cont, &params);
+
+        quote! {
+            #[automatically_derived]
+            impl #de_impl_generics #serde::Deserialize<#delife> for #ident #ty_generics #where_clause {
+                fn deserialize<__D>(__deserializer: __D) -> #serde::__private::Result<Self, __D::Error>
+                where
+                    __D: #serde::Deserializer<#delife>,
+                {
+                    #body
+                }
+
+                #fn_deserialize_in_place
+            }
+        }
+    };
+
+    Ok(dummy::wrap_in_const(
+        cont.attrs.custom_serde_path(),
+        "DESERIALIZE",
+        ident,
+        impl_block,
+    ))
+}
+
+fn precondition(cx: &Ctxt, cont: &Container) {
+    precondition_sized(cx, cont);
+    precondition_no_de_lifetime(cx, cont);
+}
+
+fn precondition_sized(cx: &Ctxt, cont: &Container) {
+    if let Data::Struct(_, fields) = &cont.data {
+        if let Some(last) = fields.last() {
+            if let syn::Type::Slice(_) = ungroup(last.ty) {
+                cx.error_spanned_by(
+                    cont.original,
+                    "cannot deserialize a dynamically sized struct",
+                );
+            }
+        }
+    }
+}
+
+fn precondition_no_de_lifetime(cx: &Ctxt, cont: &Container) {
+    if let BorrowedLifetimes::Borrowed(_) = borrowed_lifetimes(cont) {
+        for param in cont.generics.lifetimes() {
+            if param.lifetime.to_string() == "'de" {
+                cx.error_spanned_by(
+                    &param.lifetime,
+                    "cannot deserialize when there is a lifetime parameter called 'de",
+                );
+                return;
+            }
+        }
+    }
+}
+
+struct Parameters {
+    /// Name of the type the `derive` is on.
+    local: syn::Ident,
+
+    /// Path to the type the impl is for. Either a single `Ident` for local
+    /// types (does not include generic parameters) or `some::remote::Path` for
+    /// remote types.
+    this_type: syn::Path,
+
+    /// Same as `this_type` but using `::<T>` for generic parameters for use in
+    /// expression position.
+    this_value: syn::Path,
+
+    /// Generics including any explicit and inferred bounds for the impl.
+    generics: syn::Generics,
+
+    /// Lifetimes borrowed from the deserializer. These will become bounds on
+    /// the `'de` lifetime of the deserializer.
+    borrowed: BorrowedLifetimes,
+
+    /// At least one field has a serde(getter) attribute, implying that the
+    /// remote type has a private field.
+    has_getter: bool,
+
+    /// Type has a repr(packed) attribute.
+    is_packed: bool,
+}
+
+impl Parameters {
+    fn new(cont: &Container) -> Self {
+        let local = cont.ident.clone();
+        let this_type = this::this_type(cont);
+        let this_value = this::this_value(cont);
+        let borrowed = borrowed_lifetimes(cont);
+        let generics = build_generics(cont, &borrowed);
+        let has_getter = cont.data.has_getter();
+        let is_packed = cont.attrs.is_packed();
+
+        Parameters {
+            local,
+            this_type,
+            this_value,
+            generics,
+            borrowed,
+            has_getter,
+            is_packed,
+        }
+    }
+
+    /// Type name to use in error messages and `&'static str` arguments to
+    /// various Deserializer methods.
+    fn type_name(&self) -> String {
+        self.this_type.segments.last().unwrap().ident.to_string()
+    }
+}
+
+// All the generics in the input, plus a bound `T: Deserialize` for each generic
+// field type that will be deserialized by us, plus a bound `T: Default` for
+// each generic field type that will be set to a default value.
+fn build_generics(cont: &Container, borrowed: &BorrowedLifetimes) -> syn::Generics {
+    let generics = bound::without_defaults(cont.generics);
+
+    let generics = bound::with_where_predicates_from_fields(cont, &generics, attr::Field::de_bound);
+
+    let generics =
+        bound::with_where_predicates_from_variants(cont, &generics, attr::Variant::de_bound);
+
+    match cont.attrs.de_bound() {
+        Some(predicates) => bound::with_where_predicates(&generics, predicates),
+        None => {
+            let generics = match *cont.attrs.default() {
+                attr::Default::Default => bound::with_self_bound(
+                    cont,
+                    &generics,
+                    &parse_quote!(_serde::__private::Default),
+                ),
+                attr::Default::None | attr::Default::Path(_) => generics,
+            };
+
+            let delife = borrowed.de_lifetime();
+            let generics = bound::with_bound(
+                cont,
+                &generics,
+                needs_deserialize_bound,
+                &parse_quote!(_serde::Deserialize<#delife>),
+            );
+
+            bound::with_bound(
+                cont,
+                &generics,
+                requires_default,
+                &parse_quote!(_serde::__private::Default),
+            )
+        }
+    }
+}
+
+// Fields with a `skip_deserializing` or `deserialize_with` attribute, or which
+// belong to a variant with a `skip_deserializing` or `deserialize_with`
+// attribute, are not deserialized by us so we do not generate a bound. Fields
+// with a `bound` attribute specify their own bound so we do not generate one.
+// All other fields may need a `T: Deserialize` bound where T is the type of the
+// field.
+fn needs_deserialize_bound(field: &attr::Field, variant: Option<&attr::Variant>) -> bool {
+    !field.skip_deserializing()
+        && field.deserialize_with().is_none()
+        && field.de_bound().is_none()
+        && variant.map_or(true, |variant| {
+            !variant.skip_deserializing()
+                && variant.deserialize_with().is_none()
+                && variant.de_bound().is_none()
+        })
+}
+
+// Fields with a `default` attribute (not `default=...`), and fields with a
+// `skip_deserializing` attribute that do not also have `default=...`.
+fn requires_default(field: &attr::Field, _variant: Option<&attr::Variant>) -> bool {
+    if let attr::Default::Default = *field.default() {
+        true
+    } else {
+        false
+    }
+}
+
+enum BorrowedLifetimes {
+    Borrowed(BTreeSet<syn::Lifetime>),
+    Static,
+}
+
+impl BorrowedLifetimes {
+    fn de_lifetime(&self) -> syn::Lifetime {
+        match *self {
+            BorrowedLifetimes::Borrowed(_) => syn::Lifetime::new("'de", Span::call_site()),
+            BorrowedLifetimes::Static => syn::Lifetime::new("'static", Span::call_site()),
+        }
+    }
+
+    fn de_lifetime_def(&self) -> Option<syn::LifetimeDef> {
+        match self {
+            BorrowedLifetimes::Borrowed(bounds) => Some(syn::LifetimeDef {
+                attrs: Vec::new(),
+                lifetime: syn::Lifetime::new("'de", Span::call_site()),
+                colon_token: None,
+                bounds: bounds.iter().cloned().collect(),
+            }),
+            BorrowedLifetimes::Static => None,
+        }
+    }
+}
+
+// The union of lifetimes borrowed by each field of the container.
+//
+// These turn into bounds on the `'de` lifetime of the Deserialize impl. If
+// lifetimes `'a` and `'b` are borrowed but `'c` is not, the impl is:
+//
+//     impl<'de: 'a + 'b, 'a, 'b, 'c> Deserialize<'de> for S<'a, 'b, 'c>
+//
+// If any borrowed lifetime is `'static`, then `'de: 'static` would be redundant
+// and we use plain `'static` instead of `'de`.
+fn borrowed_lifetimes(cont: &Container) -> BorrowedLifetimes {
+    let mut lifetimes = BTreeSet::new();
+    for field in cont.data.all_fields() {
+        if !field.attrs.skip_deserializing() {
+            lifetimes.extend(field.attrs.borrowed_lifetimes().iter().cloned());
+        }
+    }
+    if lifetimes.iter().any(|b| b.to_string() == "'static") {
+        BorrowedLifetimes::Static
+    } else {
+        BorrowedLifetimes::Borrowed(lifetimes)
+    }
+}
+
+fn deserialize_body(cont: &Container, params: &Parameters) -> Fragment {
+    if cont.attrs.transparent() {
+        deserialize_transparent(cont, params)
+    } else if let Some(type_from) = cont.attrs.type_from() {
+        deserialize_from(type_from)
+    } else if let Some(type_try_from) = cont.attrs.type_try_from() {
+        deserialize_try_from(type_try_from)
+    } else if let attr::Identifier::No = cont.attrs.identifier() {
+        match &cont.data {
+            Data::Enum(variants) => deserialize_enum(params, variants, &cont.attrs),
+            Data::Struct(Style::Struct, fields) => {
+                deserialize_struct(None, params, fields, &cont.attrs, None, &Untagged::No)
+            }
+            Data::Struct(Style::Tuple, fields) | Data::Struct(Style::Newtype, fields) => {
+                deserialize_tuple(None, params, fields, &cont.attrs, None)
+            }
+            Data::Struct(Style::Unit, _) => deserialize_unit_struct(params, &cont.attrs),
+        }
+    } else {
+        match &cont.data {
+            Data::Enum(variants) => deserialize_custom_identifier(params, variants, &cont.attrs),
+            Data::Struct(_, _) => unreachable!("checked in serde_derive_internals"),
+        }
+    }
+}
+
+#[cfg(feature = "deserialize_in_place")]
+fn deserialize_in_place_body(cont: &Container, params: &Parameters) -> Option<Stmts> {
+    // Only remote derives have getters, and we do not generate
+    // deserialize_in_place for remote derives.
+    assert!(!params.has_getter);
+
+    if cont.attrs.transparent()
+        || cont.attrs.type_from().is_some()
+        || cont.attrs.type_try_from().is_some()
+        || cont.attrs.identifier().is_some()
+        || cont
+            .data
+            .all_fields()
+            .all(|f| f.attrs.deserialize_with().is_some())
+    {
+        return None;
+    }
+
+    let code = match &cont.data {
+        Data::Struct(Style::Struct, fields) => {
+            deserialize_struct_in_place(None, params, fields, &cont.attrs, None)?
+        }
+        Data::Struct(Style::Tuple, fields) | Data::Struct(Style::Newtype, fields) => {
+            deserialize_tuple_in_place(None, params, fields, &cont.attrs, None)
+        }
+        Data::Enum(_) | Data::Struct(Style::Unit, _) => {
+            return None;
+        }
+    };
+
+    let delife = params.borrowed.de_lifetime();
+    let stmts = Stmts(code);
+
+    let fn_deserialize_in_place = quote_block! {
+        fn deserialize_in_place<__D>(__deserializer: __D, __place: &mut Self) -> _serde::__private::Result<(), __D::Error>
+        where
+            __D: _serde::Deserializer<#delife>,
+        {
+            #stmts
+        }
+    };
+
+    Some(Stmts(fn_deserialize_in_place))
+}
+
+#[cfg(not(feature = "deserialize_in_place"))]
+fn deserialize_in_place_body(_cont: &Container, _params: &Parameters) -> Option<Stmts> {
+    None
+}
+
+fn deserialize_transparent(cont: &Container, params: &Parameters) -> Fragment {
+    let fields = match &cont.data {
+        Data::Struct(_, fields) => fields,
+        Data::Enum(_) => unreachable!(),
+    };
+
+    let this_value = &params.this_value;
+    let transparent_field = fields.iter().find(|f| f.attrs.transparent()).unwrap();
+
+    let path = match transparent_field.attrs.deserialize_with() {
+        Some(path) => quote!(#path),
+        None => {
+            let span = transparent_field.original.span();
+            quote_spanned!(span=> _serde::Deserialize::deserialize)
+        }
+    };
+
+    let assign = fields.iter().map(|field| {
+        let member = &field.member;
+        if ptr::eq(field, transparent_field) {
+            quote!(#member: __transparent)
+        } else {
+            let value = match field.attrs.default() {
+                attr::Default::Default => quote!(_serde::__private::Default::default()),
+                attr::Default::Path(path) => quote!(#path()),
+                attr::Default::None => quote!(_serde::__private::PhantomData),
+            };
+            quote!(#member: #value)
+        }
+    });
+
+    quote_block! {
+        _serde::__private::Result::map(
+            #path(__deserializer),
+            |__transparent| #this_value { #(#assign),* })
+    }
+}
+
+fn deserialize_from(type_from: &syn::Type) -> Fragment {
+    quote_block! {
+        _serde::__private::Result::map(
+            <#type_from as _serde::Deserialize>::deserialize(__deserializer),
+            _serde::__private::From::from)
+    }
+}
+
+fn deserialize_try_from(type_try_from: &syn::Type) -> Fragment {
+    quote_block! {
+        _serde::__private::Result::and_then(
+            <#type_try_from as _serde::Deserialize>::deserialize(__deserializer),
+            |v| _serde::__private::TryFrom::try_from(v).map_err(_serde::de::Error::custom))
+    }
+}
+
+fn deserialize_unit_struct(params: &Parameters, cattrs: &attr::Container) -> Fragment {
+    let this_type = &params.this_type;
+    let this_value = &params.this_value;
+    let type_name = cattrs.name().deserialize_name();
+
+    let expecting = format!("unit struct {}", params.type_name());
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
+
+    quote_block! {
+        struct __Visitor;
+
+        impl<'de> _serde::de::Visitor<'de> for __Visitor {
+            type Value = #this_type;
+
+            fn expecting(&self, __formatter: &mut _serde::__private::Formatter) -> _serde::__private::fmt::Result {
+                _serde::__private::Formatter::write_str(__formatter, #expecting)
+            }
+
+            #[inline]
+            fn visit_unit<__E>(self) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(#this_value)
+            }
+        }
+
+        _serde::Deserializer::deserialize_unit_struct(__deserializer, #type_name, __Visitor)
+    }
+}
+
+fn deserialize_tuple(
+    variant_ident: Option<&syn::Ident>,
+    params: &Parameters,
+    fields: &[Field],
+    cattrs: &attr::Container,
+    deserializer: Option<TokenStream>,
+) -> Fragment {
+    let this_type = &params.this_type;
+    let this_value = &params.this_value;
+    let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
+        split_with_de_lifetime(params);
+    let delife = params.borrowed.de_lifetime();
+
+    assert!(!cattrs.has_flatten());
+
+    // If there are getters (implying private fields), construct the local type
+    // and use an `Into` conversion to get the remote type. If there are no
+    // getters then construct the target type directly.
+    let construct = if params.has_getter {
+        let local = &params.local;
+        quote!(#local)
+    } else {
+        quote!(#this_value)
+    };
+
+    let is_enum = variant_ident.is_some();
+    let type_path = match variant_ident {
+        Some(variant_ident) => quote!(#construct::#variant_ident),
+        None => construct,
+    };
+    let expecting = match variant_ident {
+        Some(variant_ident) => format!("tuple variant {}::{}", params.type_name(), variant_ident),
+        None => format!("tuple struct {}", params.type_name()),
+    };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
+
+    let nfields = fields.len();
+
+    let visit_newtype_struct = if !is_enum && nfields == 1 {
+        Some(deserialize_newtype_struct(&type_path, params, &fields[0]))
+    } else {
+        None
+    };
+
+    let visit_seq = Stmts(deserialize_seq(
+        &type_path, params, fields, false, cattrs, expecting,
+    ));
+
+    let visitor_expr = quote! {
+        __Visitor {
+            marker: _serde::__private::PhantomData::<#this_type #ty_generics>,
+            lifetime: _serde::__private::PhantomData,
+        }
+    };
+    let dispatch = if let Some(deserializer) = deserializer {
+        quote!(_serde::Deserializer::deserialize_tuple(#deserializer, #nfields, #visitor_expr))
+    } else if is_enum {
+        quote!(_serde::de::VariantAccess::tuple_variant(__variant, #nfields, #visitor_expr))
+    } else if nfields == 1 {
+        let type_name = cattrs.name().deserialize_name();
+        quote!(_serde::Deserializer::deserialize_newtype_struct(__deserializer, #type_name, #visitor_expr))
+    } else {
+        let type_name = cattrs.name().deserialize_name();
+        quote!(_serde::Deserializer::deserialize_tuple_struct(__deserializer, #type_name, #nfields, #visitor_expr))
+    };
+
+    let all_skipped = fields.iter().all(|field| field.attrs.skip_deserializing());
+    let visitor_var = if all_skipped {
+        quote!(_)
+    } else {
+        quote!(mut __seq)
+    };
+
+    quote_block! {
+        struct __Visitor #de_impl_generics #where_clause {
+            marker: _serde::__private::PhantomData<#this_type #ty_generics>,
+            lifetime: _serde::__private::PhantomData<&#delife ()>,
+        }
+
+        impl #de_impl_generics _serde::de::Visitor<#delife> for __Visitor #de_ty_generics #where_clause {
+            type Value = #this_type #ty_generics;
+
+            fn expecting(&self, __formatter: &mut _serde::__private::Formatter) -> _serde::__private::fmt::Result {
+                _serde::__private::Formatter::write_str(__formatter, #expecting)
+            }
+
+            #visit_newtype_struct
+
+            #[inline]
+            fn visit_seq<__A>(self, #visitor_var: __A) -> _serde::__private::Result<Self::Value, __A::Error>
+            where
+                __A: _serde::de::SeqAccess<#delife>,
+            {
+                #visit_seq
+            }
+        }
+
+        #dispatch
+    }
+}
+
+#[cfg(feature = "deserialize_in_place")]
+fn deserialize_tuple_in_place(
+    variant_ident: Option<syn::Ident>,
+    params: &Parameters,
+    fields: &[Field],
+    cattrs: &attr::Container,
+    deserializer: Option<TokenStream>,
+) -> Fragment {
+    let this_type = &params.this_type;
+    let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
+        split_with_de_lifetime(params);
+    let delife = params.borrowed.de_lifetime();
+
+    assert!(!cattrs.has_flatten());
+
+    let is_enum = variant_ident.is_some();
+    let expecting = match variant_ident {
+        Some(variant_ident) => format!("tuple variant {}::{}", params.type_name(), variant_ident),
+        None => format!("tuple struct {}", params.type_name()),
+    };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
+
+    let nfields = fields.len();
+
+    let visit_newtype_struct = if !is_enum && nfields == 1 {
+        Some(deserialize_newtype_struct_in_place(params, &fields[0]))
+    } else {
+        None
+    };
+
+    let visit_seq = Stmts(deserialize_seq_in_place(params, fields, cattrs, expecting));
+
+    let visitor_expr = quote! {
+        __Visitor {
+            place: __place,
+            lifetime: _serde::__private::PhantomData,
+        }
+    };
+
+    let dispatch = if let Some(deserializer) = deserializer {
+        quote!(_serde::Deserializer::deserialize_tuple(#deserializer, #nfields, #visitor_expr))
+    } else if is_enum {
+        quote!(_serde::de::VariantAccess::tuple_variant(__variant, #nfields, #visitor_expr))
+    } else if nfields == 1 {
+        let type_name = cattrs.name().deserialize_name();
+        quote!(_serde::Deserializer::deserialize_newtype_struct(__deserializer, #type_name, #visitor_expr))
+    } else {
+        let type_name = cattrs.name().deserialize_name();
+        quote!(_serde::Deserializer::deserialize_tuple_struct(__deserializer, #type_name, #nfields, #visitor_expr))
+    };
+
+    let all_skipped = fields.iter().all(|field| field.attrs.skip_deserializing());
+    let visitor_var = if all_skipped {
+        quote!(_)
+    } else {
+        quote!(mut __seq)
+    };
+
+    let in_place_impl_generics = de_impl_generics.in_place();
+    let in_place_ty_generics = de_ty_generics.in_place();
+    let place_life = place_lifetime();
+
+    quote_block! {
+        struct __Visitor #in_place_impl_generics #where_clause {
+            place: &#place_life mut #this_type #ty_generics,
+            lifetime: _serde::__private::PhantomData<&#delife ()>,
+        }
+
+        impl #in_place_impl_generics _serde::de::Visitor<#delife> for __Visitor #in_place_ty_generics #where_clause {
+            type Value = ();
+
+            fn expecting(&self, __formatter: &mut _serde::__private::Formatter) -> _serde::__private::fmt::Result {
+                _serde::__private::Formatter::write_str(__formatter, #expecting)
+            }
+
+            #visit_newtype_struct
+
+            #[inline]
+            fn visit_seq<__A>(self, #visitor_var: __A) -> _serde::__private::Result<Self::Value, __A::Error>
+            where
+                __A: _serde::de::SeqAccess<#delife>,
+            {
+                #visit_seq
+            }
+        }
+
+        #dispatch
+    }
+}
+
+fn deserialize_seq(
+    type_path: &TokenStream,
+    params: &Parameters,
+    fields: &[Field],
+    is_struct: bool,
+    cattrs: &attr::Container,
+    expecting: &str,
+) -> Fragment {
+    let vars = (0..fields.len()).map(field_i as fn(_) -> _);
+
+    let deserialized_count = fields
+        .iter()
+        .filter(|field| !field.attrs.skip_deserializing())
+        .count();
+    let expecting = if deserialized_count == 1 {
+        format!("{} with 1 element", expecting)
+    } else {
+        format!("{} with {} elements", expecting, deserialized_count)
+    };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
+
+    let mut index_in_seq = 0_usize;
+    let let_values = vars.clone().zip(fields).map(|(var, field)| {
+        if field.attrs.skip_deserializing() {
+            let default = Expr(expr_is_missing(field, cattrs));
+            quote! {
+                let #var = #default;
+            }
+        } else {
+            let visit = match field.attrs.deserialize_with() {
+                None => {
+                    let field_ty = field.ty;
+                    let span = field.original.span();
+                    let func =
+                        quote_spanned!(span=> _serde::de::SeqAccess::next_element::<#field_ty>);
+                    quote!(try!(#func(&mut __seq)))
+                }
+                Some(path) => {
+                    let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
+                    quote!({
+                        #wrapper
+                        _serde::__private::Option::map(
+                            try!(_serde::de::SeqAccess::next_element::<#wrapper_ty>(&mut __seq)),
+                            |__wrap| __wrap.value)
+                    })
+                }
+            };
+            let value_if_none = match field.attrs.default() {
+                attr::Default::Default => quote!(_serde::__private::Default::default()),
+                attr::Default::Path(path) => quote!(#path()),
+                attr::Default::None => quote!(
+                    return _serde::__private::Err(_serde::de::Error::invalid_length(#index_in_seq, &#expecting));
+                ),
+            };
+            let assign = quote! {
+                let #var = match #visit {
+                    _serde::__private::Some(__value) => __value,
+                    _serde::__private::None => {
+                        #value_if_none
+                    }
+                };
+            };
+            index_in_seq += 1;
+            assign
+        }
+    });
+
+    let mut result = if is_struct {
+        let names = fields.iter().map(|f| &f.member);
+        quote! {
+            #type_path { #( #names: #vars ),* }
+        }
+    } else {
+        quote! {
+            #type_path ( #(#vars),* )
+        }
+    };
+
+    if params.has_getter {
+        let this_type = &params.this_type;
+        let (_, ty_generics, _) = params.generics.split_for_impl();
+        result = quote! {
+            _serde::__private::Into::<#this_type #ty_generics>::into(#result)
+        };
+    }
+
+    let let_default = match cattrs.default() {
+        attr::Default::Default => Some(quote!(
+            let __default: Self::Value = _serde::__private::Default::default();
+        )),
+        attr::Default::Path(path) => Some(quote!(
+            let __default: Self::Value = #path();
+        )),
+        attr::Default::None => {
+            // We don't need the default value, to prevent an unused variable warning
+            // we'll leave the line empty.
+            None
+        }
+    };
+
+    quote_block! {
+        #let_default
+        #(#let_values)*
+        _serde::__private::Ok(#result)
+    }
+}
+
+#[cfg(feature = "deserialize_in_place")]
+fn deserialize_seq_in_place(
+    params: &Parameters,
+    fields: &[Field],
+    cattrs: &attr::Container,
+    expecting: &str,
+) -> Fragment {
+    let deserialized_count = fields
+        .iter()
+        .filter(|field| !field.attrs.skip_deserializing())
+        .count();
+    let expecting = if deserialized_count == 1 {
+        format!("{} with 1 element", expecting)
+    } else {
+        format!("{} with {} elements", expecting, deserialized_count)
+    };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
+
+    let mut index_in_seq = 0usize;
+    let write_values = fields.iter().map(|field| {
+        let member = &field.member;
+
+        if field.attrs.skip_deserializing() {
+            let default = Expr(expr_is_missing(field, cattrs));
+            quote! {
+                self.place.#member = #default;
+            }
+        } else {
+            let value_if_none = match field.attrs.default() {
+                attr::Default::Default => quote!(
+                    self.place.#member = _serde::__private::Default::default();
+                ),
+                attr::Default::Path(path) => quote!(
+                    self.place.#member = #path();
+                ),
+                attr::Default::None => quote!(
+                    return _serde::__private::Err(_serde::de::Error::invalid_length(#index_in_seq, &#expecting));
+                ),
+            };
+            let write = match field.attrs.deserialize_with() {
+                None => {
+                    quote! {
+                        if let _serde::__private::None = try!(_serde::de::SeqAccess::next_element_seed(&mut __seq,
+                            _serde::__private::de::InPlaceSeed(&mut self.place.#member)))
+                        {
+                            #value_if_none
+                        }
+                    }
+                }
+                Some(path) => {
+                    let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
+                    quote!({
+                        #wrapper
+                        match try!(_serde::de::SeqAccess::next_element::<#wrapper_ty>(&mut __seq)) {
+                            _serde::__private::Some(__wrap) => {
+                                self.place.#member = __wrap.value;
+                            }
+                            _serde::__private::None => {
+                                #value_if_none
+                            }
+                        }
+                    })
+                }
+            };
+            index_in_seq += 1;
+            write
+        }
+    });
+
+    let this_type = &params.this_type;
+    let (_, ty_generics, _) = params.generics.split_for_impl();
+    let let_default = match cattrs.default() {
+        attr::Default::Default => Some(quote!(
+            let __default: #this_type #ty_generics = _serde::__private::Default::default();
+        )),
+        attr::Default::Path(path) => Some(quote!(
+            let __default: #this_type #ty_generics = #path();
+        )),
+        attr::Default::None => {
+            // We don't need the default value, to prevent an unused variable warning
+            // we'll leave the line empty.
+            None
+        }
+    };
+
+    quote_block! {
+        #let_default
+        #(#write_values)*
+        _serde::__private::Ok(())
+    }
+}
+
+fn deserialize_newtype_struct(
+    type_path: &TokenStream,
+    params: &Parameters,
+    field: &Field,
+) -> TokenStream {
+    let delife = params.borrowed.de_lifetime();
+    let field_ty = field.ty;
+
+    let value = match field.attrs.deserialize_with() {
+        None => {
+            let span = field.original.span();
+            let func = quote_spanned!(span=> <#field_ty as _serde::Deserialize>::deserialize);
+            quote! {
+                try!(#func(__e))
+            }
+        }
+        Some(path) => {
+            quote! {
+                try!(#path(__e))
+            }
+        }
+    };
+
+    let mut result = quote!(#type_path(__field0));
+    if params.has_getter {
+        let this_type = &params.this_type;
+        let (_, ty_generics, _) = params.generics.split_for_impl();
+        result = quote! {
+            _serde::__private::Into::<#this_type #ty_generics>::into(#result)
+        };
+    }
+
+    quote! {
+        #[inline]
+        fn visit_newtype_struct<__E>(self, __e: __E) -> _serde::__private::Result<Self::Value, __E::Error>
+        where
+            __E: _serde::Deserializer<#delife>,
+        {
+            let __field0: #field_ty = #value;
+            _serde::__private::Ok(#result)
+        }
+    }
+}
+
+#[cfg(feature = "deserialize_in_place")]
+fn deserialize_newtype_struct_in_place(params: &Parameters, field: &Field) -> TokenStream {
+    // We do not generate deserialize_in_place if every field has a
+    // deserialize_with.
+    assert!(field.attrs.deserialize_with().is_none());
+
+    let delife = params.borrowed.de_lifetime();
+
+    quote! {
+        #[inline]
+        fn visit_newtype_struct<__E>(self, __e: __E) -> _serde::__private::Result<Self::Value, __E::Error>
+        where
+            __E: _serde::Deserializer<#delife>,
+        {
+            _serde::Deserialize::deserialize_in_place(__e, &mut self.place.0)
+        }
+    }
+}
+
+enum Untagged {
+    Yes,
+    No,
+}
+
+fn deserialize_struct(
+    variant_ident: Option<&syn::Ident>,
+    params: &Parameters,
+    fields: &[Field],
+    cattrs: &attr::Container,
+    deserializer: Option<TokenStream>,
+    untagged: &Untagged,
+) -> Fragment {
+    let is_enum = variant_ident.is_some();
+
+    let this_type = &params.this_type;
+    let this_value = &params.this_value;
+    let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
+        split_with_de_lifetime(params);
+    let delife = params.borrowed.de_lifetime();
+
+    // If there are getters (implying private fields), construct the local type
+    // and use an `Into` conversion to get the remote type. If there are no
+    // getters then construct the target type directly.
+    let construct = if params.has_getter {
+        let local = &params.local;
+        quote!(#local)
+    } else {
+        quote!(#this_value)
+    };
+
+    let type_path = match variant_ident {
+        Some(variant_ident) => quote!(#construct::#variant_ident),
+        None => construct,
+    };
+    let expecting = match variant_ident {
+        Some(variant_ident) => format!("struct variant {}::{}", params.type_name(), variant_ident),
+        None => format!("struct {}", params.type_name()),
+    };
+    let expecting = cattrs.expecting().unwrap_or(&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)
+    } else {
+        deserialize_struct_as_struct_visitor(&type_path, params, fields, cattrs)
+    };
+    let field_visitor = Stmts(field_visitor);
+    let fields_stmt = fields_stmt.map(Stmts);
+    let visit_map = Stmts(visit_map);
+
+    let visitor_expr = quote! {
+        __Visitor {
+            marker: _serde::__private::PhantomData::<#this_type #ty_generics>,
+            lifetime: _serde::__private::PhantomData,
+        }
+    };
+    let dispatch = if let Some(deserializer) = deserializer {
+        quote! {
+            _serde::Deserializer::deserialize_any(#deserializer, #visitor_expr)
+        }
+    } else if is_enum && cattrs.has_flatten() {
+        quote! {
+            _serde::de::VariantAccess::newtype_variant_seed(__variant, #visitor_expr)
+        }
+    } else if is_enum {
+        quote! {
+            _serde::de::VariantAccess::struct_variant(__variant, FIELDS, #visitor_expr)
+        }
+    } else if cattrs.has_flatten() {
+        quote! {
+            _serde::Deserializer::deserialize_map(__deserializer, #visitor_expr)
+        }
+    } else {
+        let type_name = cattrs.name().deserialize_name();
+        quote! {
+            _serde::Deserializer::deserialize_struct(__deserializer, #type_name, FIELDS, #visitor_expr)
+        }
+    };
+
+    let all_skipped = fields.iter().all(|field| field.attrs.skip_deserializing());
+    let visitor_var = if all_skipped {
+        quote!(_)
+    } else {
+        quote!(mut __seq)
+    };
+
+    // untagged struct variants do not get a visit_seq method. The same applies to
+    // structs that only have a map representation.
+    let visit_seq = match *untagged {
+        Untagged::No if !cattrs.has_flatten() => Some(quote! {
+            #[inline]
+            fn visit_seq<__A>(self, #visitor_var: __A) -> _serde::__private::Result<Self::Value, __A::Error>
+            where
+                __A: _serde::de::SeqAccess<#delife>,
+            {
+                #visit_seq
+            }
+        }),
+        _ => None,
+    };
+
+    let visitor_seed = if is_enum && cattrs.has_flatten() {
+        Some(quote! {
+            impl #de_impl_generics _serde::de::DeserializeSeed<#delife> for __Visitor #de_ty_generics #where_clause {
+                type Value = #this_type #ty_generics;
+
+                fn deserialize<__D>(self, __deserializer: __D) -> _serde::__private::Result<Self::Value, __D::Error>
+                where
+                    __D: _serde::Deserializer<'de>,
+                {
+                    _serde::Deserializer::deserialize_map(__deserializer, self)
+                }
+            }
+        })
+    } else {
+        None
+    };
+
+    quote_block! {
+        #field_visitor
+
+        struct __Visitor #de_impl_generics #where_clause {
+            marker: _serde::__private::PhantomData<#this_type #ty_generics>,
+            lifetime: _serde::__private::PhantomData<&#delife ()>,
+        }
+
+        impl #de_impl_generics _serde::de::Visitor<#delife> for __Visitor #de_ty_generics #where_clause {
+            type Value = #this_type #ty_generics;
+
+            fn expecting(&self, __formatter: &mut _serde::__private::Formatter) -> _serde::__private::fmt::Result {
+                _serde::__private::Formatter::write_str(__formatter, #expecting)
+            }
+
+            #visit_seq
+
+            #[inline]
+            fn visit_map<__A>(self, mut __map: __A) -> _serde::__private::Result<Self::Value, __A::Error>
+            where
+                __A: _serde::de::MapAccess<#delife>,
+            {
+                #visit_map
+            }
+        }
+
+        #visitor_seed
+
+        #fields_stmt
+
+        #dispatch
+    }
+}
+
+#[cfg(feature = "deserialize_in_place")]
+fn deserialize_struct_in_place(
+    variant_ident: Option<syn::Ident>,
+    params: &Parameters,
+    fields: &[Field],
+    cattrs: &attr::Container,
+    deserializer: Option<TokenStream>,
+) -> Option<Fragment> {
+    let is_enum = variant_ident.is_some();
+
+    // for now we do not support in_place deserialization for structs that
+    // are represented as map.
+    if cattrs.has_flatten() {
+        return None;
+    }
+
+    let this_type = &params.this_type;
+    let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
+        split_with_de_lifetime(params);
+    let delife = params.borrowed.de_lifetime();
+
+    let expecting = match variant_ident {
+        Some(variant_ident) => format!("struct variant {}::{}", params.type_name(), variant_ident),
+        None => format!("struct {}", params.type_name()),
+    };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
+
+    let visit_seq = Stmts(deserialize_seq_in_place(params, fields, cattrs, expecting));
+
+    let (field_visitor, fields_stmt, visit_map) =
+        deserialize_struct_as_struct_in_place_visitor(params, fields, cattrs);
+
+    let field_visitor = Stmts(field_visitor);
+    let fields_stmt = Stmts(fields_stmt);
+    let visit_map = Stmts(visit_map);
+
+    let visitor_expr = quote! {
+        __Visitor {
+            place: __place,
+            lifetime: _serde::__private::PhantomData,
+        }
+    };
+    let dispatch = if let Some(deserializer) = deserializer {
+        quote! {
+            _serde::Deserializer::deserialize_any(#deserializer, #visitor_expr)
+        }
+    } else if is_enum {
+        quote! {
+            _serde::de::VariantAccess::struct_variant(__variant, FIELDS, #visitor_expr)
+        }
+    } else {
+        let type_name = cattrs.name().deserialize_name();
+        quote! {
+            _serde::Deserializer::deserialize_struct(__deserializer, #type_name, FIELDS, #visitor_expr)
+        }
+    };
+
+    let all_skipped = fields.iter().all(|field| field.attrs.skip_deserializing());
+    let visitor_var = if all_skipped {
+        quote!(_)
+    } else {
+        quote!(mut __seq)
+    };
+
+    let visit_seq = quote! {
+        #[inline]
+        fn visit_seq<__A>(self, #visitor_var: __A) -> _serde::__private::Result<Self::Value, __A::Error>
+        where
+            __A: _serde::de::SeqAccess<#delife>,
+        {
+            #visit_seq
+        }
+    };
+
+    let in_place_impl_generics = de_impl_generics.in_place();
+    let in_place_ty_generics = de_ty_generics.in_place();
+    let place_life = place_lifetime();
+
+    Some(quote_block! {
+        #field_visitor
+
+        struct __Visitor #in_place_impl_generics #where_clause {
+            place: &#place_life mut #this_type #ty_generics,
+            lifetime: _serde::__private::PhantomData<&#delife ()>,
+        }
+
+        impl #in_place_impl_generics _serde::de::Visitor<#delife> for __Visitor #in_place_ty_generics #where_clause {
+            type Value = ();
+
+            fn expecting(&self, __formatter: &mut _serde::__private::Formatter) -> _serde::__private::fmt::Result {
+                _serde::__private::Formatter::write_str(__formatter, #expecting)
+            }
+
+            #visit_seq
+
+            #[inline]
+            fn visit_map<__A>(self, mut __map: __A) -> _serde::__private::Result<Self::Value, __A::Error>
+            where
+                __A: _serde::de::MapAccess<#delife>,
+            {
+                #visit_map
+            }
+        }
+
+        #fields_stmt
+
+        #dispatch
+    })
+}
+
+fn deserialize_enum(
+    params: &Parameters,
+    variants: &[Variant],
+    cattrs: &attr::Container,
+) -> Fragment {
+    match cattrs.tag() {
+        attr::TagType::External => deserialize_externally_tagged_enum(params, variants, cattrs),
+        attr::TagType::Internal { tag } => {
+            deserialize_internally_tagged_enum(params, variants, cattrs, tag)
+        }
+        attr::TagType::Adjacent { tag, content } => {
+            deserialize_adjacently_tagged_enum(params, variants, cattrs, tag, content)
+        }
+        attr::TagType::None => deserialize_untagged_enum(params, variants, cattrs),
+    }
+}
+
+fn prepare_enum_variant_enum(
+    variants: &[Variant],
+    cattrs: &attr::Container,
+) -> (TokenStream, Stmts) {
+    let mut deserialized_variants = variants
+        .iter()
+        .enumerate()
+        .filter(|&(_, variant)| !variant.attrs.skip_deserializing());
+
+    let variant_names_idents: Vec<_> = deserialized_variants
+        .clone()
+        .map(|(i, variant)| {
+            (
+                variant.attrs.name().deserialize_name(),
+                field_i(i),
+                variant.attrs.aliases(),
+            )
+        })
+        .collect();
+
+    let other_idx = deserialized_variants.position(|(_, variant)| variant.attrs.other());
+
+    let variants_stmt = {
+        let variant_names = variant_names_idents.iter().map(|(name, _, _)| name);
+        quote! {
+            const VARIANTS: &'static [&'static str] = &[ #(#variant_names),* ];
+        }
+    };
+
+    let variant_visitor = Stmts(deserialize_generated_identifier(
+        &variant_names_idents,
+        cattrs,
+        true,
+        other_idx,
+    ));
+
+    (variants_stmt, variant_visitor)
+}
+
+fn deserialize_externally_tagged_enum(
+    params: &Parameters,
+    variants: &[Variant],
+    cattrs: &attr::Container,
+) -> Fragment {
+    let this_type = &params.this_type;
+    let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
+        split_with_de_lifetime(params);
+    let delife = params.borrowed.de_lifetime();
+
+    let type_name = cattrs.name().deserialize_name();
+    let expecting = format!("enum {}", params.type_name());
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
+
+    let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants, cattrs);
+
+    // Match arms to extract a variant from a string
+    let variant_arms = variants
+        .iter()
+        .enumerate()
+        .filter(|&(_, variant)| !variant.attrs.skip_deserializing())
+        .map(|(i, variant)| {
+            let variant_name = field_i(i);
+
+            let block = Match(deserialize_externally_tagged_variant(
+                params, variant, cattrs,
+            ));
+
+            quote! {
+                (__Field::#variant_name, __variant) => #block
+            }
+        });
+
+    let all_skipped = variants
+        .iter()
+        .all(|variant| variant.attrs.skip_deserializing());
+    let match_variant = if all_skipped {
+        // This is an empty enum like `enum Impossible {}` or an enum in which
+        // all variants have `#[serde(skip_deserializing)]`.
+        quote! {
+            // FIXME: Once we drop support for Rust 1.15:
+            // let _serde::__private::Err(__err) = _serde::de::EnumAccess::variant::<__Field>(__data);
+            // _serde::__private::Err(__err)
+            _serde::__private::Result::map(
+                _serde::de::EnumAccess::variant::<__Field>(__data),
+                |(__impossible, _)| match __impossible {})
+        }
+    } else {
+        quote! {
+            match try!(_serde::de::EnumAccess::variant(__data)) {
+                #(#variant_arms)*
+            }
+        }
+    };
+
+    quote_block! {
+        #variant_visitor
+
+        struct __Visitor #de_impl_generics #where_clause {
+            marker: _serde::__private::PhantomData<#this_type #ty_generics>,
+            lifetime: _serde::__private::PhantomData<&#delife ()>,
+        }
+
+        impl #de_impl_generics _serde::de::Visitor<#delife> for __Visitor #de_ty_generics #where_clause {
+            type Value = #this_type #ty_generics;
+
+            fn expecting(&self, __formatter: &mut _serde::__private::Formatter) -> _serde::__private::fmt::Result {
+                _serde::__private::Formatter::write_str(__formatter, #expecting)
+            }
+
+            fn visit_enum<__A>(self, __data: __A) -> _serde::__private::Result<Self::Value, __A::Error>
+            where
+                __A: _serde::de::EnumAccess<#delife>,
+            {
+                #match_variant
+            }
+        }
+
+        #variants_stmt
+
+        _serde::Deserializer::deserialize_enum(
+            __deserializer,
+            #type_name,
+            VARIANTS,
+            __Visitor {
+                marker: _serde::__private::PhantomData::<#this_type #ty_generics>,
+                lifetime: _serde::__private::PhantomData,
+            },
+        )
+    }
+}
+
+fn deserialize_internally_tagged_enum(
+    params: &Parameters,
+    variants: &[Variant],
+    cattrs: &attr::Container,
+    tag: &str,
+) -> Fragment {
+    let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants, cattrs);
+
+    // Match arms to extract a variant from a string
+    let variant_arms = variants
+        .iter()
+        .enumerate()
+        .filter(|&(_, variant)| !variant.attrs.skip_deserializing())
+        .map(|(i, variant)| {
+            let variant_name = field_i(i);
+
+            let block = Match(deserialize_internally_tagged_variant(
+                params,
+                variant,
+                cattrs,
+                quote! {
+                    _serde::__private::de::ContentDeserializer::<__D::Error>::new(__tagged.content)
+                },
+            ));
+
+            quote! {
+                __Field::#variant_name => #block
+            }
+        });
+
+    let expecting = format!("internally tagged enum {}", params.type_name());
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
+
+    quote_block! {
+        #variant_visitor
+
+        #variants_stmt
+
+        let __tagged = try!(_serde::Deserializer::deserialize_any(
+            __deserializer,
+            _serde::__private::de::TaggedContentVisitor::<__Field>::new(#tag, #expecting)));
+
+        match __tagged.tag {
+            #(#variant_arms)*
+        }
+    }
+}
+
+fn deserialize_adjacently_tagged_enum(
+    params: &Parameters,
+    variants: &[Variant],
+    cattrs: &attr::Container,
+    tag: &str,
+    content: &str,
+) -> Fragment {
+    let this_type = &params.this_type;
+    let this_value = &params.this_value;
+    let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
+        split_with_de_lifetime(params);
+    let delife = params.borrowed.de_lifetime();
+
+    let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants, cattrs);
+
+    let variant_arms: &Vec<_> = &variants
+        .iter()
+        .enumerate()
+        .filter(|&(_, variant)| !variant.attrs.skip_deserializing())
+        .map(|(i, variant)| {
+            let variant_index = field_i(i);
+
+            let block = Match(deserialize_untagged_variant(
+                params,
+                variant,
+                cattrs,
+                quote!(__deserializer),
+            ));
+
+            quote! {
+                __Field::#variant_index => #block
+            }
+        })
+        .collect();
+
+    let expecting = format!("adjacently tagged enum {}", params.type_name());
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
+    let type_name = cattrs.name().deserialize_name();
+    let deny_unknown_fields = cattrs.deny_unknown_fields();
+
+    // If unknown fields are allowed, we pick the visitor that can step over
+    // those. Otherwise we pick the visitor that fails on unknown keys.
+    let field_visitor_ty = if deny_unknown_fields {
+        quote! { _serde::__private::de::TagOrContentFieldVisitor }
+    } else {
+        quote! { _serde::__private::de::TagContentOtherFieldVisitor }
+    };
+
+    let tag_or_content = quote! {
+        #field_visitor_ty {
+            tag: #tag,
+            content: #content,
+        }
+    };
+
+    let mut missing_content = quote! {
+        _serde::__private::Err(<__A::Error as _serde::de::Error>::missing_field(#content))
+    };
+    let mut missing_content_fallthrough = quote!();
+    let missing_content_arms = variants
+        .iter()
+        .enumerate()
+        .filter(|&(_, variant)| !variant.attrs.skip_deserializing())
+        .filter_map(|(i, variant)| {
+            let variant_index = field_i(i);
+            let variant_ident = &variant.ident;
+
+            let arm = match variant.style {
+                Style::Unit => quote! {
+                    _serde::__private::Ok(#this_value::#variant_ident)
+                },
+                Style::Newtype if variant.attrs.deserialize_with().is_none() => {
+                    let span = variant.original.span();
+                    let func = quote_spanned!(span=> _serde::__private::de::missing_field);
+                    quote! {
+                        #func(#content).map(#this_value::#variant_ident)
+                    }
+                }
+                _ => {
+                    missing_content_fallthrough = quote!(_ => #missing_content);
+                    return None;
+                }
+            };
+            Some(quote! {
+                __Field::#variant_index => #arm,
+            })
+        })
+        .collect::<Vec<_>>();
+    if !missing_content_arms.is_empty() {
+        missing_content = quote! {
+            match __field {
+                #(#missing_content_arms)*
+                #missing_content_fallthrough
+            }
+        };
+    }
+
+    // Advance the map by one key, returning early in case of error.
+    let next_key = quote! {
+        try!(_serde::de::MapAccess::next_key_seed(&mut __map, #tag_or_content))
+    };
+
+    // When allowing unknown fields, we want to transparently step through keys
+    // we don't care about until we find `tag`, `content`, or run out of keys.
+    let next_relevant_key = if deny_unknown_fields {
+        next_key
+    } else {
+        quote!({
+            let mut __rk : _serde::__private::Option<_serde::__private::de::TagOrContentField> = _serde::__private::None;
+            while let _serde::__private::Some(__k) = #next_key {
+                match __k {
+                    _serde::__private::de::TagContentOtherField::Other => {
+                        let _ = try!(_serde::de::MapAccess::next_value::<_serde::de::IgnoredAny>(&mut __map));
+                        continue;
+                    },
+                    _serde::__private::de::TagContentOtherField::Tag => {
+                        __rk = _serde::__private::Some(_serde::__private::de::TagOrContentField::Tag);
+                        break;
+                    }
+                    _serde::__private::de::TagContentOtherField::Content => {
+                        __rk = _serde::__private::Some(_serde::__private::de::TagOrContentField::Content);
+                        break;
+                    }
+                }
+            }
+
+            __rk
+        })
+    };
+
+    // Step through remaining keys, looking for duplicates of previously-seen
+    // keys. When unknown fields are denied, any key that isn't a duplicate will
+    // at this point immediately produce an error.
+    let visit_remaining_keys = quote! {
+        match #next_relevant_key {
+            _serde::__private::Some(_serde::__private::de::TagOrContentField::Tag) => {
+                _serde::__private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#tag))
+            }
+            _serde::__private::Some(_serde::__private::de::TagOrContentField::Content) => {
+                _serde::__private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#content))
+            }
+            _serde::__private::None => _serde::__private::Ok(__ret),
+        }
+    };
+
+    let finish_content_then_tag = if variant_arms.is_empty() {
+        quote! {
+            match try!(_serde::de::MapAccess::next_value::<__Field>(&mut __map)) {}
+        }
+    } else {
+        quote! {
+            let __ret = try!(match try!(_serde::de::MapAccess::next_value(&mut __map)) {
+                // Deserialize the buffered content now that we know the variant.
+                #(#variant_arms)*
+            });
+            // Visit remaining keys, looking for duplicates.
+            #visit_remaining_keys
+        }
+    };
+
+    quote_block! {
+        #variant_visitor
+
+        #variants_stmt
+
+        struct __Seed #de_impl_generics #where_clause {
+            field: __Field,
+            marker: _serde::__private::PhantomData<#this_type #ty_generics>,
+            lifetime: _serde::__private::PhantomData<&#delife ()>,
+        }
+
+        impl #de_impl_generics _serde::de::DeserializeSeed<#delife> for __Seed #de_ty_generics #where_clause {
+            type Value = #this_type #ty_generics;
+
+            fn deserialize<__D>(self, __deserializer: __D) -> _serde::__private::Result<Self::Value, __D::Error>
+            where
+                __D: _serde::Deserializer<#delife>,
+            {
+                match self.field {
+                    #(#variant_arms)*
+                }
+            }
+        }
+
+        struct __Visitor #de_impl_generics #where_clause {
+            marker: _serde::__private::PhantomData<#this_type #ty_generics>,
+            lifetime: _serde::__private::PhantomData<&#delife ()>,
+        }
+
+        impl #de_impl_generics _serde::de::Visitor<#delife> for __Visitor #de_ty_generics #where_clause {
+            type Value = #this_type #ty_generics;
+
+            fn expecting(&self, __formatter: &mut _serde::__private::Formatter) -> _serde::__private::fmt::Result {
+                _serde::__private::Formatter::write_str(__formatter, #expecting)
+            }
+
+            fn visit_map<__A>(self, mut __map: __A) -> _serde::__private::Result<Self::Value, __A::Error>
+            where
+                __A: _serde::de::MapAccess<#delife>,
+            {
+                // Visit the first relevant key.
+                match #next_relevant_key {
+                    // First key is the tag.
+                    _serde::__private::Some(_serde::__private::de::TagOrContentField::Tag) => {
+                        // Parse the tag.
+                        let __field = try!(_serde::de::MapAccess::next_value(&mut __map));
+                        // Visit the second key.
+                        match #next_relevant_key {
+                            // Second key is a duplicate of the tag.
+                            _serde::__private::Some(_serde::__private::de::TagOrContentField::Tag) => {
+                                _serde::__private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#tag))
+                            }
+                            // Second key is the content.
+                            _serde::__private::Some(_serde::__private::de::TagOrContentField::Content) => {
+                                let __ret = try!(_serde::de::MapAccess::next_value_seed(&mut __map,
+                                    __Seed {
+                                        field: __field,
+                                        marker: _serde::__private::PhantomData,
+                                        lifetime: _serde::__private::PhantomData,
+                                    }));
+                                // Visit remaining keys, looking for duplicates.
+                                #visit_remaining_keys
+                            }
+                            // There is no second key; might be okay if the we have a unit variant.
+                            _serde::__private::None => #missing_content
+                        }
+                    }
+                    // First key is the content.
+                    _serde::__private::Some(_serde::__private::de::TagOrContentField::Content) => {
+                        // Buffer up the content.
+                        let __content = try!(_serde::de::MapAccess::next_value::<_serde::__private::de::Content>(&mut __map));
+                        // Visit the second key.
+                        match #next_relevant_key {
+                            // Second key is the tag.
+                            _serde::__private::Some(_serde::__private::de::TagOrContentField::Tag) => {
+                                let __deserializer = _serde::__private::de::ContentDeserializer::<__A::Error>::new(__content);
+                                #finish_content_then_tag
+                            }
+                            // Second key is a duplicate of the content.
+                            _serde::__private::Some(_serde::__private::de::TagOrContentField::Content) => {
+                                _serde::__private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#content))
+                            }
+                            // There is no second key.
+                            _serde::__private::None => {
+                                _serde::__private::Err(<__A::Error as _serde::de::Error>::missing_field(#tag))
+                            }
+                        }
+                    }
+                    // There is no first key.
+                    _serde::__private::None => {
+                        _serde::__private::Err(<__A::Error as _serde::de::Error>::missing_field(#tag))
+                    }
+                }
+            }
+
+            fn visit_seq<__A>(self, mut __seq: __A) -> _serde::__private::Result<Self::Value, __A::Error>
+            where
+                __A: _serde::de::SeqAccess<#delife>,
+            {
+                // Visit the first element - the tag.
+                match try!(_serde::de::SeqAccess::next_element(&mut __seq)) {
+                    _serde::__private::Some(__field) => {
+                        // Visit the second element - the content.
+                        match try!(_serde::de::SeqAccess::next_element_seed(
+                            &mut __seq,
+                            __Seed {
+                                field: __field,
+                                marker: _serde::__private::PhantomData,
+                                lifetime: _serde::__private::PhantomData,
+                            },
+                        )) {
+                            _serde::__private::Some(__ret) => _serde::__private::Ok(__ret),
+                            // There is no second element.
+                            _serde::__private::None => {
+                                _serde::__private::Err(_serde::de::Error::invalid_length(1, &self))
+                            }
+                        }
+                    }
+                    // There is no first element.
+                    _serde::__private::None => {
+                        _serde::__private::Err(_serde::de::Error::invalid_length(0, &self))
+                    }
+                }
+            }
+        }
+
+        const FIELDS: &'static [&'static str] = &[#tag, #content];
+        _serde::Deserializer::deserialize_struct(
+            __deserializer,
+            #type_name,
+            FIELDS,
+            __Visitor {
+                marker: _serde::__private::PhantomData::<#this_type #ty_generics>,
+                lifetime: _serde::__private::PhantomData,
+            },
+        )
+    }
+}
+
+fn deserialize_untagged_enum(
+    params: &Parameters,
+    variants: &[Variant],
+    cattrs: &attr::Container,
+) -> Fragment {
+    let attempts = variants
+        .iter()
+        .filter(|variant| !variant.attrs.skip_deserializing())
+        .map(|variant| {
+            Expr(deserialize_untagged_variant(
+                params,
+                variant,
+                cattrs,
+                quote!(
+                    _serde::__private::de::ContentRefDeserializer::<__D::Error>::new(&__content)
+                ),
+            ))
+        });
+
+    // TODO this message could be better by saving the errors from the failed
+    // attempts. The heuristic used by TOML was to count the number of fields
+    // processed before an error, and use the error that happened after the
+    // largest number of fields. I'm not sure I like that. Maybe it would be
+    // better to save all the errors and combine them into one message that
+    // explains why none of the variants matched.
+    let fallthrough_msg = format!(
+        "data did not match any variant of untagged enum {}",
+        params.type_name()
+    );
+    let fallthrough_msg = cattrs.expecting().unwrap_or(&fallthrough_msg);
+
+    quote_block! {
+        let __content = try!(<_serde::__private::de::Content as _serde::Deserialize>::deserialize(__deserializer));
+
+        #(
+            if let _serde::__private::Ok(__ok) = #attempts {
+                return _serde::__private::Ok(__ok);
+            }
+        )*
+
+        _serde::__private::Err(_serde::de::Error::custom(#fallthrough_msg))
+    }
+}
+
+fn deserialize_externally_tagged_variant(
+    params: &Parameters,
+    variant: &Variant,
+    cattrs: &attr::Container,
+) -> Fragment {
+    if let Some(path) = variant.attrs.deserialize_with() {
+        let (wrapper, wrapper_ty, unwrap_fn) = wrap_deserialize_variant_with(params, variant, path);
+        return quote_block! {
+            #wrapper
+            _serde::__private::Result::map(
+                _serde::de::VariantAccess::newtype_variant::<#wrapper_ty>(__variant), #unwrap_fn)
+        };
+    }
+
+    let variant_ident = &variant.ident;
+
+    match variant.style {
+        Style::Unit => {
+            let this_value = &params.this_value;
+            quote_block! {
+                try!(_serde::de::VariantAccess::unit_variant(__variant));
+                _serde::__private::Ok(#this_value::#variant_ident)
+            }
+        }
+        Style::Newtype => deserialize_externally_tagged_newtype_variant(
+            variant_ident,
+            params,
+            &variant.fields[0],
+            cattrs,
+        ),
+        Style::Tuple => {
+            deserialize_tuple(Some(variant_ident), params, &variant.fields, cattrs, None)
+        }
+        Style::Struct => deserialize_struct(
+            Some(variant_ident),
+            params,
+            &variant.fields,
+            cattrs,
+            None,
+            &Untagged::No,
+        ),
+    }
+}
+
+// Generates significant part of the visit_seq and visit_map bodies of visitors
+// for the variants of internally tagged enum.
+fn deserialize_internally_tagged_variant(
+    params: &Parameters,
+    variant: &Variant,
+    cattrs: &attr::Container,
+    deserializer: TokenStream,
+) -> Fragment {
+    if variant.attrs.deserialize_with().is_some() {
+        return deserialize_untagged_variant(params, variant, cattrs, deserializer);
+    }
+
+    let variant_ident = &variant.ident;
+
+    match effective_style(variant) {
+        Style::Unit => {
+            let this_value = &params.this_value;
+            let type_name = params.type_name();
+            let variant_name = variant.ident.to_string();
+            let default = variant.fields.get(0).map(|field| {
+                let default = Expr(expr_is_missing(field, cattrs));
+                quote!((#default))
+            });
+            quote_block! {
+                try!(_serde::Deserializer::deserialize_any(#deserializer, _serde::__private::de::InternallyTaggedUnitVisitor::new(#type_name, #variant_name)));
+                _serde::__private::Ok(#this_value::#variant_ident #default)
+            }
+        }
+        Style::Newtype => deserialize_untagged_newtype_variant(
+            variant_ident,
+            params,
+            &variant.fields[0],
+            &deserializer,
+        ),
+        Style::Struct => deserialize_struct(
+            Some(variant_ident),
+            params,
+            &variant.fields,
+            cattrs,
+            Some(deserializer),
+            &Untagged::No,
+        ),
+        Style::Tuple => unreachable!("checked in serde_derive_internals"),
+    }
+}
+
+fn deserialize_untagged_variant(
+    params: &Parameters,
+    variant: &Variant,
+    cattrs: &attr::Container,
+    deserializer: TokenStream,
+) -> Fragment {
+    if let Some(path) = variant.attrs.deserialize_with() {
+        let unwrap_fn = unwrap_to_variant_closure(params, variant, false);
+        return quote_block! {
+            _serde::__private::Result::map(#path(#deserializer), #unwrap_fn)
+        };
+    }
+
+    let variant_ident = &variant.ident;
+
+    match effective_style(variant) {
+        Style::Unit => {
+            let this_value = &params.this_value;
+            let type_name = params.type_name();
+            let variant_name = variant.ident.to_string();
+            let default = variant.fields.get(0).map(|field| {
+                let default = Expr(expr_is_missing(field, cattrs));
+                quote!((#default))
+            });
+            quote_expr! {
+                match _serde::Deserializer::deserialize_any(
+                    #deserializer,
+                    _serde::__private::de::UntaggedUnitVisitor::new(#type_name, #variant_name)
+                ) {
+                    _serde::__private::Ok(()) => _serde::__private::Ok(#this_value::#variant_ident #default),
+                    _serde::__private::Err(__err) => _serde::__private::Err(__err),
+                }
+            }
+        }
+        Style::Newtype => deserialize_untagged_newtype_variant(
+            variant_ident,
+            params,
+            &variant.fields[0],
+            &deserializer,
+        ),
+        Style::Tuple => deserialize_tuple(
+            Some(variant_ident),
+            params,
+            &variant.fields,
+            cattrs,
+            Some(deserializer),
+        ),
+        Style::Struct => deserialize_struct(
+            Some(variant_ident),
+            params,
+            &variant.fields,
+            cattrs,
+            Some(deserializer),
+            &Untagged::Yes,
+        ),
+    }
+}
+
+fn deserialize_externally_tagged_newtype_variant(
+    variant_ident: &syn::Ident,
+    params: &Parameters,
+    field: &Field,
+    cattrs: &attr::Container,
+) -> Fragment {
+    let this_value = &params.this_value;
+
+    if field.attrs.skip_deserializing() {
+        let default = Expr(expr_is_missing(field, cattrs));
+        return quote_block! {
+            try!(_serde::de::VariantAccess::unit_variant(__variant));
+            _serde::__private::Ok(#this_value::#variant_ident(#default))
+        };
+    }
+
+    match field.attrs.deserialize_with() {
+        None => {
+            let field_ty = field.ty;
+            let span = field.original.span();
+            let func =
+                quote_spanned!(span=> _serde::de::VariantAccess::newtype_variant::<#field_ty>);
+            quote_expr! {
+                _serde::__private::Result::map(#func(__variant), #this_value::#variant_ident)
+            }
+        }
+        Some(path) => {
+            let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
+            quote_block! {
+                #wrapper
+                _serde::__private::Result::map(
+                    _serde::de::VariantAccess::newtype_variant::<#wrapper_ty>(__variant),
+                    |__wrapper| #this_value::#variant_ident(__wrapper.value))
+            }
+        }
+    }
+}
+
+fn deserialize_untagged_newtype_variant(
+    variant_ident: &syn::Ident,
+    params: &Parameters,
+    field: &Field,
+    deserializer: &TokenStream,
+) -> Fragment {
+    let this_value = &params.this_value;
+    let field_ty = field.ty;
+    match field.attrs.deserialize_with() {
+        None => {
+            let span = field.original.span();
+            let func = quote_spanned!(span=> <#field_ty as _serde::Deserialize>::deserialize);
+            quote_expr! {
+                _serde::__private::Result::map(#func(#deserializer), #this_value::#variant_ident)
+            }
+        }
+        Some(path) => {
+            quote_block! {
+                let __value: _serde::__private::Result<#field_ty, _> = #path(#deserializer);
+                _serde::__private::Result::map(__value, #this_value::#variant_ident)
+            }
+        }
+    }
+}
+
+fn deserialize_generated_identifier(
+    fields: &[(String, Ident, Vec<String>)],
+    cattrs: &attr::Container,
+    is_variant: bool,
+    other_idx: Option<usize>,
+) -> Fragment {
+    let this_value = quote!(__Field);
+    let field_idents: &Vec<_> = &fields.iter().map(|(_, ident, _)| ident).collect();
+
+    let (ignore_variant, fallthrough) = if !is_variant && cattrs.has_flatten() {
+        let ignore_variant = quote!(__other(_serde::__private::de::Content<'de>),);
+        let fallthrough = quote!(_serde::__private::Ok(__Field::__other(__value)));
+        (Some(ignore_variant), Some(fallthrough))
+    } else if let Some(other_idx) = other_idx {
+        let ignore_variant = fields[other_idx].1.clone();
+        let fallthrough = quote!(_serde::__private::Ok(__Field::#ignore_variant));
+        (None, Some(fallthrough))
+    } else if is_variant || cattrs.deny_unknown_fields() {
+        (None, None)
+    } else {
+        let ignore_variant = quote!(__ignore,);
+        let fallthrough = quote!(_serde::__private::Ok(__Field::__ignore));
+        (Some(ignore_variant), Some(fallthrough))
+    };
+
+    let visitor_impl = Stmts(deserialize_identifier(
+        &this_value,
+        fields,
+        is_variant,
+        fallthrough,
+        None,
+        !is_variant && cattrs.has_flatten(),
+        None,
+    ));
+
+    let lifetime = if !is_variant && cattrs.has_flatten() {
+        Some(quote!(<'de>))
+    } else {
+        None
+    };
+
+    quote_block! {
+        #[allow(non_camel_case_types)]
+        enum __Field #lifetime {
+            #(#field_idents,)*
+            #ignore_variant
+        }
+
+        struct __FieldVisitor;
+
+        impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
+            type Value = __Field #lifetime;
+
+            #visitor_impl
+        }
+
+        impl<'de> _serde::Deserialize<'de> for __Field #lifetime {
+            #[inline]
+            fn deserialize<__D>(__deserializer: __D) -> _serde::__private::Result<Self, __D::Error>
+            where
+                __D: _serde::Deserializer<'de>,
+            {
+                _serde::Deserializer::deserialize_identifier(__deserializer, __FieldVisitor)
+            }
+        }
+    }
+}
+
+// Generates `Deserialize::deserialize` body for an enum with
+// `serde(field_identifier)` or `serde(variant_identifier)` attribute.
+fn deserialize_custom_identifier(
+    params: &Parameters,
+    variants: &[Variant],
+    cattrs: &attr::Container,
+) -> Fragment {
+    let is_variant = match cattrs.identifier() {
+        attr::Identifier::Variant => true,
+        attr::Identifier::Field => false,
+        attr::Identifier::No => unreachable!(),
+    };
+
+    let this_type = params.this_type.to_token_stream();
+    let this_value = params.this_value.to_token_stream();
+
+    let (ordinary, fallthrough, fallthrough_borrowed) = if let Some(last) = variants.last() {
+        let last_ident = &last.ident;
+        if last.attrs.other() {
+            // Process `serde(other)` attribute. It would always be found on the
+            // last variant (checked in `check_identifier`), so all preceding
+            // are ordinary variants.
+            let ordinary = &variants[..variants.len() - 1];
+            let fallthrough = quote!(_serde::__private::Ok(#this_value::#last_ident));
+            (ordinary, Some(fallthrough), None)
+        } else if let Style::Newtype = last.style {
+            let ordinary = &variants[..variants.len() - 1];
+            let fallthrough = |value| {
+                quote! {
+                    _serde::__private::Result::map(
+                        _serde::Deserialize::deserialize(
+                            _serde::__private::de::IdentifierDeserializer::from(#value)
+                        ),
+                        #this_value::#last_ident)
+                }
+            };
+            (
+                ordinary,
+                Some(fallthrough(quote!(__value))),
+                Some(fallthrough(quote!(_serde::__private::de::Borrowed(
+                    __value
+                )))),
+            )
+        } else {
+            (variants, None, None)
+        }
+    } else {
+        (variants, None, None)
+    };
+
+    let names_idents: Vec<_> = ordinary
+        .iter()
+        .map(|variant| {
+            (
+                variant.attrs.name().deserialize_name(),
+                variant.ident.clone(),
+                variant.attrs.aliases(),
+            )
+        })
+        .collect();
+
+    let names = names_idents.iter().map(|(name, _, _)| name);
+
+    let names_const = if fallthrough.is_some() {
+        None
+    } else if is_variant {
+        let variants = quote! {
+            const VARIANTS: &'static [&'static str] = &[ #(#names),* ];
+        };
+        Some(variants)
+    } else {
+        let fields = quote! {
+            const FIELDS: &'static [&'static str] = &[ #(#names),* ];
+        };
+        Some(fields)
+    };
+
+    let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
+        split_with_de_lifetime(params);
+    let delife = params.borrowed.de_lifetime();
+    let visitor_impl = Stmts(deserialize_identifier(
+        &this_value,
+        &names_idents,
+        is_variant,
+        fallthrough,
+        fallthrough_borrowed,
+        false,
+        cattrs.expecting(),
+    ));
+
+    quote_block! {
+        #names_const
+
+        struct __FieldVisitor #de_impl_generics #where_clause {
+            marker: _serde::__private::PhantomData<#this_type #ty_generics>,
+            lifetime: _serde::__private::PhantomData<&#delife ()>,
+        }
+
+        impl #de_impl_generics _serde::de::Visitor<#delife> for __FieldVisitor #de_ty_generics #where_clause {
+            type Value = #this_type #ty_generics;
+
+            #visitor_impl
+        }
+
+        let __visitor = __FieldVisitor {
+            marker: _serde::__private::PhantomData::<#this_type #ty_generics>,
+            lifetime: _serde::__private::PhantomData,
+        };
+        _serde::Deserializer::deserialize_identifier(__deserializer, __visitor)
+    }
+}
+
+fn deserialize_identifier(
+    this_value: &TokenStream,
+    fields: &[(String, Ident, Vec<String>)],
+    is_variant: bool,
+    fallthrough: Option<TokenStream>,
+    fallthrough_borrowed: Option<TokenStream>,
+    collect_other_fields: bool,
+    expecting: Option<&str>,
+) -> Fragment {
+    let mut flat_fields = Vec::new();
+    for (_, ident, aliases) in fields {
+        flat_fields.extend(aliases.iter().map(|alias| (alias, ident)));
+    }
+
+    let field_strs: &Vec<_> = &flat_fields.iter().map(|(name, _)| name).collect();
+    let field_bytes: &Vec<_> = &flat_fields
+        .iter()
+        .map(|(name, _)| Literal::byte_string(name.as_bytes()))
+        .collect();
+
+    let constructors: &Vec<_> = &flat_fields
+        .iter()
+        .map(|(_, ident)| quote!(#this_value::#ident))
+        .collect();
+    let main_constructors: &Vec<_> = &fields
+        .iter()
+        .map(|(_, ident, _)| quote!(#this_value::#ident))
+        .collect();
+
+    let expecting = expecting.unwrap_or(if is_variant {
+        "variant identifier"
+    } else {
+        "field identifier"
+    });
+
+    let index_expecting = if is_variant { "variant" } else { "field" };
+
+    let bytes_to_str = if fallthrough.is_some() || collect_other_fields {
+        None
+    } else {
+        Some(quote! {
+            let __value = &_serde::__private::from_utf8_lossy(__value);
+        })
+    };
+
+    let (
+        value_as_str_content,
+        value_as_borrowed_str_content,
+        value_as_bytes_content,
+        value_as_borrowed_bytes_content,
+    ) = if collect_other_fields {
+        (
+            Some(quote! {
+                let __value = _serde::__private::de::Content::String(_serde::__private::ToString::to_string(__value));
+            }),
+            Some(quote! {
+                let __value = _serde::__private::de::Content::Str(__value);
+            }),
+            Some(quote! {
+                let __value = _serde::__private::de::Content::ByteBuf(__value.to_vec());
+            }),
+            Some(quote! {
+                let __value = _serde::__private::de::Content::Bytes(__value);
+            }),
+        )
+    } else {
+        (None, None, None, None)
+    };
+
+    let fallthrough_arm_tokens;
+    let fallthrough_arm = if let Some(fallthrough) = &fallthrough {
+        fallthrough
+    } else if is_variant {
+        fallthrough_arm_tokens = quote! {
+            _serde::__private::Err(_serde::de::Error::unknown_variant(__value, VARIANTS))
+        };
+        &fallthrough_arm_tokens
+    } else {
+        fallthrough_arm_tokens = quote! {
+            _serde::__private::Err(_serde::de::Error::unknown_field(__value, FIELDS))
+        };
+        &fallthrough_arm_tokens
+    };
+
+    let u64_fallthrough_arm_tokens;
+    let u64_fallthrough_arm = if let Some(fallthrough) = &fallthrough {
+        fallthrough
+    } else {
+        let fallthrough_msg = format!("{} index 0 <= i < {}", index_expecting, fields.len());
+        u64_fallthrough_arm_tokens = quote! {
+            _serde::__private::Err(_serde::de::Error::invalid_value(
+                _serde::de::Unexpected::Unsigned(__value),
+                &#fallthrough_msg,
+            ))
+        };
+        &u64_fallthrough_arm_tokens
+    };
+
+    let variant_indices = 0_u64..;
+    let visit_other = if collect_other_fields {
+        quote! {
+            fn visit_bool<__E>(self, __value: bool) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::Bool(__value)))
+            }
+
+            fn visit_i8<__E>(self, __value: i8) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::I8(__value)))
+            }
+
+            fn visit_i16<__E>(self, __value: i16) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::I16(__value)))
+            }
+
+            fn visit_i32<__E>(self, __value: i32) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::I32(__value)))
+            }
+
+            fn visit_i64<__E>(self, __value: i64) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::I64(__value)))
+            }
+
+            fn visit_u8<__E>(self, __value: u8) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::U8(__value)))
+            }
+
+            fn visit_u16<__E>(self, __value: u16) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::U16(__value)))
+            }
+
+            fn visit_u32<__E>(self, __value: u32) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::U32(__value)))
+            }
+
+            fn visit_u64<__E>(self, __value: u64) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::U64(__value)))
+            }
+
+            fn visit_f32<__E>(self, __value: f32) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::F32(__value)))
+            }
+
+            fn visit_f64<__E>(self, __value: f64) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::F64(__value)))
+            }
+
+            fn visit_char<__E>(self, __value: char) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::Char(__value)))
+            }
+
+            fn visit_unit<__E>(self) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                _serde::__private::Ok(__Field::__other(_serde::__private::de::Content::Unit))
+            }
+        }
+    } else {
+        quote! {
+            fn visit_u64<__E>(self, __value: u64) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                match __value {
+                    #(
+                        #variant_indices => _serde::__private::Ok(#main_constructors),
+                    )*
+                    _ => #u64_fallthrough_arm,
+                }
+            }
+        }
+    };
+
+    let visit_borrowed = if fallthrough_borrowed.is_some() || collect_other_fields {
+        let fallthrough_borrowed_arm = fallthrough_borrowed.as_ref().unwrap_or(fallthrough_arm);
+        Some(quote! {
+            fn visit_borrowed_str<__E>(self, __value: &'de str) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                match __value {
+                    #(
+                        #field_strs => _serde::__private::Ok(#constructors),
+                    )*
+                    _ => {
+                        #value_as_borrowed_str_content
+                        #fallthrough_borrowed_arm
+                    }
+                }
+            }
+
+            fn visit_borrowed_bytes<__E>(self, __value: &'de [u8]) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                match __value {
+                    #(
+                        #field_bytes => _serde::__private::Ok(#constructors),
+                    )*
+                    _ => {
+                        #bytes_to_str
+                        #value_as_borrowed_bytes_content
+                        #fallthrough_borrowed_arm
+                    }
+                }
+            }
+        })
+    } else {
+        None
+    };
+
+    quote_block! {
+        fn expecting(&self, __formatter: &mut _serde::__private::Formatter) -> _serde::__private::fmt::Result {
+            _serde::__private::Formatter::write_str(__formatter, #expecting)
+        }
+
+        #visit_other
+
+        fn visit_str<__E>(self, __value: &str) -> _serde::__private::Result<Self::Value, __E>
+        where
+            __E: _serde::de::Error,
+        {
+            match __value {
+                #(
+                    #field_strs => _serde::__private::Ok(#constructors),
+                )*
+                _ => {
+                    #value_as_str_content
+                    #fallthrough_arm
+                }
+            }
+        }
+
+        fn visit_bytes<__E>(self, __value: &[u8]) -> _serde::__private::Result<Self::Value, __E>
+        where
+            __E: _serde::de::Error,
+        {
+            match __value {
+                #(
+                    #field_bytes => _serde::__private::Ok(#constructors),
+                )*
+                _ => {
+                    #bytes_to_str
+                    #value_as_bytes_content
+                    #fallthrough_arm
+                }
+            }
+        }
+
+        #visit_borrowed
+    }
+}
+
+fn deserialize_struct_as_struct_visitor(
+    struct_path: &TokenStream,
+    params: &Parameters,
+    fields: &[Field],
+    cattrs: &attr::Container,
+) -> (Fragment, Option<Fragment>, Fragment) {
+    assert!(!cattrs.has_flatten());
+
+    let field_names_idents: Vec<_> = fields
+        .iter()
+        .enumerate()
+        .filter(|&(_, field)| !field.attrs.skip_deserializing())
+        .map(|(i, field)| {
+            (
+                field.attrs.name().deserialize_name(),
+                field_i(i),
+                field.attrs.aliases(),
+            )
+        })
+        .collect();
+
+    let fields_stmt = {
+        let field_names = field_names_idents.iter().map(|(name, _, _)| name);
+        quote_block! {
+            const FIELDS: &'static [&'static str] = &[ #(#field_names),* ];
+        }
+    };
+
+    let field_visitor = deserialize_generated_identifier(&field_names_idents, cattrs, false, None);
+
+    let visit_map = deserialize_map(struct_path, params, fields, cattrs);
+
+    (field_visitor, Some(fields_stmt), visit_map)
+}
+
+fn deserialize_struct_as_map_visitor(
+    struct_path: &TokenStream,
+    params: &Parameters,
+    fields: &[Field],
+    cattrs: &attr::Container,
+) -> (Fragment, Option<Fragment>, Fragment) {
+    let field_names_idents: Vec<_> = fields
+        .iter()
+        .enumerate()
+        .filter(|&(_, field)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
+        .map(|(i, field)| {
+            (
+                field.attrs.name().deserialize_name(),
+                field_i(i),
+                field.attrs.aliases(),
+            )
+        })
+        .collect();
+
+    let field_visitor = deserialize_generated_identifier(&field_names_idents, cattrs, false, None);
+
+    let visit_map = deserialize_map(struct_path, params, fields, cattrs);
+
+    (field_visitor, None, visit_map)
+}
+
+fn deserialize_map(
+    struct_path: &TokenStream,
+    params: &Parameters,
+    fields: &[Field],
+    cattrs: &attr::Container,
+) -> Fragment {
+    // Create the field names for the fields.
+    let fields_names: Vec<_> = fields
+        .iter()
+        .enumerate()
+        .map(|(i, field)| (field, field_i(i)))
+        .collect();
+
+    // Declare each field that will be deserialized.
+    let let_values = fields_names
+        .iter()
+        .filter(|&&(field, _)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
+        .map(|(field, name)| {
+            let field_ty = field.ty;
+            quote! {
+                let mut #name: _serde::__private::Option<#field_ty> = _serde::__private::None;
+            }
+        });
+
+    // Collect contents for flatten fields into a buffer
+    let let_collect = if cattrs.has_flatten() {
+        Some(quote! {
+            let mut __collect = _serde::__private::Vec::<_serde::__private::Option<(
+                _serde::__private::de::Content,
+                _serde::__private::de::Content
+            )>>::new();
+        })
+    } else {
+        None
+    };
+
+    // Match arms to extract a value for a field.
+    let value_arms = fields_names
+        .iter()
+        .filter(|&&(field, _)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
+        .map(|(field, name)| {
+            let deser_name = field.attrs.name().deserialize_name();
+
+            let visit = match field.attrs.deserialize_with() {
+                None => {
+                    let field_ty = field.ty;
+                    let span = field.original.span();
+                    let func =
+                        quote_spanned!(span=> _serde::de::MapAccess::next_value::<#field_ty>);
+                    quote! {
+                        try!(#func(&mut __map))
+                    }
+                }
+                Some(path) => {
+                    let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
+                    quote!({
+                        #wrapper
+                        match _serde::de::MapAccess::next_value::<#wrapper_ty>(&mut __map) {
+                            _serde::__private::Ok(__wrapper) => __wrapper.value,
+                            _serde::__private::Err(__err) => {
+                                return _serde::__private::Err(__err);
+                            }
+                        }
+                    })
+                }
+            };
+            quote! {
+                __Field::#name => {
+                    if _serde::__private::Option::is_some(&#name) {
+                        return _serde::__private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#deser_name));
+                    }
+                    #name = _serde::__private::Some(#visit);
+                }
+            }
+        });
+
+    // Visit ignored values to consume them
+    let ignored_arm = if cattrs.has_flatten() {
+        Some(quote! {
+            __Field::__other(__name) => {
+                __collect.push(_serde::__private::Some((
+                    __name,
+                    try!(_serde::de::MapAccess::next_value(&mut __map)))));
+            }
+        })
+    } else if cattrs.deny_unknown_fields() {
+        None
+    } else {
+        Some(quote! {
+            _ => { let _ = try!(_serde::de::MapAccess::next_value::<_serde::de::IgnoredAny>(&mut __map)); }
+        })
+    };
+
+    let all_skipped = fields.iter().all(|field| field.attrs.skip_deserializing());
+    let match_keys = if cattrs.deny_unknown_fields() && all_skipped {
+        quote! {
+            // FIXME: Once we drop support for Rust 1.15:
+            // let _serde::__private::None::<__Field> = try!(_serde::de::MapAccess::next_key(&mut __map));
+            _serde::__private::Option::map(
+                try!(_serde::de::MapAccess::next_key::<__Field>(&mut __map)),
+                |__impossible| match __impossible {});
+        }
+    } else {
+        quote! {
+            while let _serde::__private::Some(__key) = try!(_serde::de::MapAccess::next_key::<__Field>(&mut __map)) {
+                match __key {
+                    #(#value_arms)*
+                    #ignored_arm
+                }
+            }
+        }
+    };
+
+    let extract_values = fields_names
+        .iter()
+        .filter(|&&(field, _)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
+        .map(|(field, name)| {
+            let missing_expr = Match(expr_is_missing(field, cattrs));
+
+            quote! {
+                let #name = match #name {
+                    _serde::__private::Some(#name) => #name,
+                    _serde::__private::None => #missing_expr
+                };
+            }
+        });
+
+    let extract_collected = fields_names
+        .iter()
+        .filter(|&&(field, _)| field.attrs.flatten() && !field.attrs.skip_deserializing())
+        .map(|(field, name)| {
+            let field_ty = field.ty;
+            let func = match field.attrs.deserialize_with() {
+                None => {
+                    let span = field.original.span();
+                    quote_spanned!(span=> _serde::de::Deserialize::deserialize)
+                }
+                Some(path) => quote!(#path),
+            };
+            quote! {
+                let #name: #field_ty = try!(#func(
+                    _serde::__private::de::FlatMapDeserializer(
+                        &mut __collect,
+                        _serde::__private::PhantomData)));
+            }
+        });
+
+    let collected_deny_unknown_fields = if cattrs.has_flatten() && cattrs.deny_unknown_fields() {
+        Some(quote! {
+            if let _serde::__private::Some(_serde::__private::Some((__key, _))) =
+                __collect.into_iter().filter(_serde::__private::Option::is_some).next()
+            {
+                if let _serde::__private::Some(__key) = __key.as_str() {
+                    return _serde::__private::Err(
+                        _serde::de::Error::custom(format_args!("unknown field `{}`", &__key)));
+                } else {
+                    return _serde::__private::Err(
+                        _serde::de::Error::custom(format_args!("unexpected map key")));
+                }
+            }
+        })
+    } else {
+        None
+    };
+
+    let result = fields_names.iter().map(|(field, name)| {
+        let member = &field.member;
+        if field.attrs.skip_deserializing() {
+            let value = Expr(expr_is_missing(field, cattrs));
+            quote!(#member: #value)
+        } else {
+            quote!(#member: #name)
+        }
+    });
+
+    let let_default = match cattrs.default() {
+        attr::Default::Default => Some(quote!(
+            let __default: Self::Value = _serde::__private::Default::default();
+        )),
+        attr::Default::Path(path) => Some(quote!(
+            let __default: Self::Value = #path();
+        )),
+        attr::Default::None => {
+            // We don't need the default value, to prevent an unused variable warning
+            // we'll leave the line empty.
+            None
+        }
+    };
+
+    let mut result = quote!(#struct_path { #(#result),* });
+    if params.has_getter {
+        let this_type = &params.this_type;
+        let (_, ty_generics, _) = params.generics.split_for_impl();
+        result = quote! {
+            _serde::__private::Into::<#this_type #ty_generics>::into(#result)
+        };
+    }
+
+    quote_block! {
+        #(#let_values)*
+
+        #let_collect
+
+        #match_keys
+
+        #let_default
+
+        #(#extract_values)*
+
+        #(#extract_collected)*
+
+        #collected_deny_unknown_fields
+
+        _serde::__private::Ok(#result)
+    }
+}
+
+#[cfg(feature = "deserialize_in_place")]
+fn deserialize_struct_as_struct_in_place_visitor(
+    params: &Parameters,
+    fields: &[Field],
+    cattrs: &attr::Container,
+) -> (Fragment, Fragment, Fragment) {
+    assert!(!cattrs.has_flatten());
+
+    let field_names_idents: Vec<_> = fields
+        .iter()
+        .enumerate()
+        .filter(|&(_, field)| !field.attrs.skip_deserializing())
+        .map(|(i, field)| {
+            (
+                field.attrs.name().deserialize_name(),
+                field_i(i),
+                field.attrs.aliases(),
+            )
+        })
+        .collect();
+
+    let fields_stmt = {
+        let field_names = field_names_idents.iter().map(|(name, _, _)| name);
+        quote_block! {
+            const FIELDS: &'static [&'static str] = &[ #(#field_names),* ];
+        }
+    };
+
+    let field_visitor = deserialize_generated_identifier(&field_names_idents, cattrs, false, None);
+
+    let visit_map = deserialize_map_in_place(params, fields, cattrs);
+
+    (field_visitor, fields_stmt, visit_map)
+}
+
+#[cfg(feature = "deserialize_in_place")]
+fn deserialize_map_in_place(
+    params: &Parameters,
+    fields: &[Field],
+    cattrs: &attr::Container,
+) -> Fragment {
+    assert!(!cattrs.has_flatten());
+
+    // Create the field names for the fields.
+    let fields_names: Vec<_> = fields
+        .iter()
+        .enumerate()
+        .map(|(i, field)| (field, field_i(i)))
+        .collect();
+
+    // For deserialize_in_place, declare booleans for each field that will be
+    // deserialized.
+    let let_flags = fields_names
+        .iter()
+        .filter(|&&(field, _)| !field.attrs.skip_deserializing())
+        .map(|(_, name)| {
+            quote! {
+                let mut #name: bool = false;
+            }
+        });
+
+    // Match arms to extract a value for a field.
+    let value_arms_from = fields_names
+        .iter()
+        .filter(|&&(field, _)| !field.attrs.skip_deserializing())
+        .map(|(field, name)| {
+            let deser_name = field.attrs.name().deserialize_name();
+            let member = &field.member;
+
+            let visit = match field.attrs.deserialize_with() {
+                None => {
+                    quote! {
+                        try!(_serde::de::MapAccess::next_value_seed(&mut __map, _serde::__private::de::InPlaceSeed(&mut self.place.#member)))
+                    }
+                }
+                Some(path) => {
+                    let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
+                    quote!({
+                        #wrapper
+                        self.place.#member = match _serde::de::MapAccess::next_value::<#wrapper_ty>(&mut __map) {
+                            _serde::__private::Ok(__wrapper) => __wrapper.value,
+                            _serde::__private::Err(__err) => {
+                                return _serde::__private::Err(__err);
+                            }
+                        };
+                    })
+                }
+            };
+            quote! {
+                __Field::#name => {
+                    if #name {
+                        return _serde::__private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#deser_name));
+                    }
+                    #visit;
+                    #name = true;
+                }
+            }
+        });
+
+    // Visit ignored values to consume them
+    let ignored_arm = if cattrs.deny_unknown_fields() {
+        None
+    } else {
+        Some(quote! {
+            _ => { let _ = try!(_serde::de::MapAccess::next_value::<_serde::de::IgnoredAny>(&mut __map)); }
+        })
+    };
+
+    let all_skipped = fields.iter().all(|field| field.attrs.skip_deserializing());
+
+    let match_keys = if cattrs.deny_unknown_fields() && all_skipped {
+        quote! {
+            // FIXME: Once we drop support for Rust 1.15:
+            // let _serde::__private::None::<__Field> = try!(_serde::de::MapAccess::next_key(&mut __map));
+            _serde::__private::Option::map(
+                try!(_serde::de::MapAccess::next_key::<__Field>(&mut __map)),
+                |__impossible| match __impossible {});
+        }
+    } else {
+        quote! {
+            while let _serde::__private::Some(__key) = try!(_serde::de::MapAccess::next_key::<__Field>(&mut __map)) {
+                match __key {
+                    #(#value_arms_from)*
+                    #ignored_arm
+                }
+            }
+        }
+    };
+
+    let check_flags = fields_names
+        .iter()
+        .filter(|&&(field, _)| !field.attrs.skip_deserializing())
+        .map(|(field, name)| {
+            let missing_expr = expr_is_missing(field, cattrs);
+            // If missing_expr unconditionally returns an error, don't try
+            // to assign its value to self.place.
+            if field.attrs.default().is_none()
+                && cattrs.default().is_none()
+                && field.attrs.deserialize_with().is_some()
+            {
+                let missing_expr = Stmts(missing_expr);
+                quote! {
+                    if !#name {
+                        #missing_expr;
+                    }
+                }
+            } else {
+                let member = &field.member;
+                let missing_expr = Expr(missing_expr);
+                quote! {
+                    if !#name {
+                        self.place.#member = #missing_expr;
+                    };
+                }
+            }
+        });
+
+    let this_type = &params.this_type;
+    let (_, _, ty_generics, _) = split_with_de_lifetime(params);
+
+    let let_default = match cattrs.default() {
+        attr::Default::Default => Some(quote!(
+            let __default: #this_type #ty_generics = _serde::__private::Default::default();
+        )),
+        attr::Default::Path(path) => Some(quote!(
+            let __default: #this_type #ty_generics = #path();
+        )),
+        attr::Default::None => {
+            // We don't need the default value, to prevent an unused variable warning
+            // we'll leave the line empty.
+            None
+        }
+    };
+
+    quote_block! {
+        #(#let_flags)*
+
+        #match_keys
+
+        #let_default
+
+        #(#check_flags)*
+
+        _serde::__private::Ok(())
+    }
+}
+
+fn field_i(i: usize) -> Ident {
+    Ident::new(&format!("__field{}", i), Span::call_site())
+}
+
+/// This function wraps the expression in `#[serde(deserialize_with = "...")]`
+/// in a trait to prevent it from accessing the internal `Deserialize` state.
+fn wrap_deserialize_with(
+    params: &Parameters,
+    value_ty: &TokenStream,
+    deserialize_with: &syn::ExprPath,
+) -> (TokenStream, TokenStream) {
+    let this_type = &params.this_type;
+    let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
+        split_with_de_lifetime(params);
+    let delife = params.borrowed.de_lifetime();
+
+    let wrapper = quote! {
+        struct __DeserializeWith #de_impl_generics #where_clause {
+            value: #value_ty,
+            phantom: _serde::__private::PhantomData<#this_type #ty_generics>,
+            lifetime: _serde::__private::PhantomData<&#delife ()>,
+        }
+
+        impl #de_impl_generics _serde::Deserialize<#delife> for __DeserializeWith #de_ty_generics #where_clause {
+            fn deserialize<__D>(__deserializer: __D) -> _serde::__private::Result<Self, __D::Error>
+            where
+                __D: _serde::Deserializer<#delife>,
+            {
+                _serde::__private::Ok(__DeserializeWith {
+                    value: try!(#deserialize_with(__deserializer)),
+                    phantom: _serde::__private::PhantomData,
+                    lifetime: _serde::__private::PhantomData,
+                })
+            }
+        }
+    };
+
+    let wrapper_ty = quote!(__DeserializeWith #de_ty_generics);
+
+    (wrapper, wrapper_ty)
+}
+
+fn wrap_deserialize_field_with(
+    params: &Parameters,
+    field_ty: &syn::Type,
+    deserialize_with: &syn::ExprPath,
+) -> (TokenStream, TokenStream) {
+    wrap_deserialize_with(params, &quote!(#field_ty), deserialize_with)
+}
+
+fn wrap_deserialize_variant_with(
+    params: &Parameters,
+    variant: &Variant,
+    deserialize_with: &syn::ExprPath,
+) -> (TokenStream, TokenStream, TokenStream) {
+    let field_tys = variant.fields.iter().map(|field| field.ty);
+    let (wrapper, wrapper_ty) =
+        wrap_deserialize_with(params, &quote!((#(#field_tys),*)), deserialize_with);
+
+    let unwrap_fn = unwrap_to_variant_closure(params, variant, true);
+
+    (wrapper, wrapper_ty, unwrap_fn)
+}
+
+// Generates closure that converts single input parameter to the final value.
+fn unwrap_to_variant_closure(
+    params: &Parameters,
+    variant: &Variant,
+    with_wrapper: bool,
+) -> TokenStream {
+    let this_value = &params.this_value;
+    let variant_ident = &variant.ident;
+
+    let (arg, wrapper) = if with_wrapper {
+        (quote! { __wrap }, quote! { __wrap.value })
+    } else {
+        let field_tys = variant.fields.iter().map(|field| field.ty);
+        (quote! { __wrap: (#(#field_tys),*) }, quote! { __wrap })
+    };
+
+    let field_access = (0..variant.fields.len()).map(|n| {
+        Member::Unnamed(Index {
+            index: n as u32,
+            span: Span::call_site(),
+        })
+    });
+
+    match variant.style {
+        Style::Struct if variant.fields.len() == 1 => {
+            let member = &variant.fields[0].member;
+            quote! {
+                |#arg| #this_value::#variant_ident { #member: #wrapper }
+            }
+        }
+        Style::Struct => {
+            let members = variant.fields.iter().map(|field| &field.member);
+            quote! {
+                |#arg| #this_value::#variant_ident { #(#members: #wrapper.#field_access),* }
+            }
+        }
+        Style::Tuple => quote! {
+            |#arg| #this_value::#variant_ident(#(#wrapper.#field_access),*)
+        },
+        Style::Newtype => quote! {
+            |#arg| #this_value::#variant_ident(#wrapper)
+        },
+        Style::Unit => quote! {
+            |#arg| #this_value::#variant_ident
+        },
+    }
+}
+
+fn expr_is_missing(field: &Field, cattrs: &attr::Container) -> Fragment {
+    match field.attrs.default() {
+        attr::Default::Default => {
+            let span = field.original.span();
+            let func = quote_spanned!(span=> _serde::__private::Default::default);
+            return quote_expr!(#func());
+        }
+        attr::Default::Path(path) => {
+            return quote_expr!(#path());
+        }
+        attr::Default::None => { /* below */ }
+    }
+
+    match *cattrs.default() {
+        attr::Default::Default | attr::Default::Path(_) => {
+            let member = &field.member;
+            return quote_expr!(__default.#member);
+        }
+        attr::Default::None => { /* below */ }
+    }
+
+    let name = field.attrs.name().deserialize_name();
+    match field.attrs.deserialize_with() {
+        None => {
+            let span = field.original.span();
+            let func = quote_spanned!(span=> _serde::__private::de::missing_field);
+            quote_expr! {
+                try!(#func(#name))
+            }
+        }
+        Some(_) => {
+            quote_expr! {
+                return _serde::__private::Err(<__A::Error as _serde::de::Error>::missing_field(#name))
+            }
+        }
+    }
+}
+
+fn effective_style(variant: &Variant) -> Style {
+    match variant.style {
+        Style::Newtype if variant.fields[0].attrs.skip_deserializing() => Style::Unit,
+        other => other,
+    }
+}
+
+struct DeImplGenerics<'a>(&'a Parameters);
+#[cfg(feature = "deserialize_in_place")]
+struct InPlaceImplGenerics<'a>(&'a Parameters);
+
+impl<'a> ToTokens for DeImplGenerics<'a> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let mut generics = self.0.generics.clone();
+        if let Some(de_lifetime) = self.0.borrowed.de_lifetime_def() {
+            generics.params = Some(syn::GenericParam::Lifetime(de_lifetime))
+                .into_iter()
+                .chain(generics.params)
+                .collect();
+        }
+        let (impl_generics, _, _) = generics.split_for_impl();
+        impl_generics.to_tokens(tokens);
+    }
+}
+
+#[cfg(feature = "deserialize_in_place")]
+impl<'a> ToTokens for InPlaceImplGenerics<'a> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let place_lifetime = place_lifetime();
+        let mut generics = self.0.generics.clone();
+
+        // Add lifetime for `&'place mut Self, and `'a: 'place`
+        for param in &mut generics.params {
+            match param {
+                syn::GenericParam::Lifetime(param) => {
+                    param.bounds.push(place_lifetime.lifetime.clone());
+                }
+                syn::GenericParam::Type(param) => {
+                    param.bounds.push(syn::TypeParamBound::Lifetime(
+                        place_lifetime.lifetime.clone(),
+                    ));
+                }
+                syn::GenericParam::Const(_) => {}
+            }
+        }
+        generics.params = Some(syn::GenericParam::Lifetime(place_lifetime))
+            .into_iter()
+            .chain(generics.params)
+            .collect();
+        if let Some(de_lifetime) = self.0.borrowed.de_lifetime_def() {
+            generics.params = Some(syn::GenericParam::Lifetime(de_lifetime))
+                .into_iter()
+                .chain(generics.params)
+                .collect();
+        }
+        let (impl_generics, _, _) = generics.split_for_impl();
+        impl_generics.to_tokens(tokens);
+    }
+}
+
+#[cfg(feature = "deserialize_in_place")]
+impl<'a> DeImplGenerics<'a> {
+    fn in_place(self) -> InPlaceImplGenerics<'a> {
+        InPlaceImplGenerics(self.0)
+    }
+}
+
+struct DeTypeGenerics<'a>(&'a Parameters);
+#[cfg(feature = "deserialize_in_place")]
+struct InPlaceTypeGenerics<'a>(&'a Parameters);
+
+impl<'a> ToTokens for DeTypeGenerics<'a> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let mut generics = self.0.generics.clone();
+        if self.0.borrowed.de_lifetime_def().is_some() {
+            let def = syn::LifetimeDef {
+                attrs: Vec::new(),
+                lifetime: syn::Lifetime::new("'de", Span::call_site()),
+                colon_token: None,
+                bounds: Punctuated::new(),
+            };
+            generics.params = Some(syn::GenericParam::Lifetime(def))
+                .into_iter()
+                .chain(generics.params)
+                .collect();
+        }
+        let (_, ty_generics, _) = generics.split_for_impl();
+        ty_generics.to_tokens(tokens);
+    }
+}
+
+#[cfg(feature = "deserialize_in_place")]
+impl<'a> ToTokens for InPlaceTypeGenerics<'a> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let mut generics = self.0.generics.clone();
+        generics.params = Some(syn::GenericParam::Lifetime(place_lifetime()))
+            .into_iter()
+            .chain(generics.params)
+            .collect();
+
+        if self.0.borrowed.de_lifetime_def().is_some() {
+            let def = syn::LifetimeDef {
+                attrs: Vec::new(),
+                lifetime: syn::Lifetime::new("'de", Span::call_site()),
+                colon_token: None,
+                bounds: Punctuated::new(),
+            };
+            generics.params = Some(syn::GenericParam::Lifetime(def))
+                .into_iter()
+                .chain(generics.params)
+                .collect();
+        }
+        let (_, ty_generics, _) = generics.split_for_impl();
+        ty_generics.to_tokens(tokens);
+    }
+}
+
+#[cfg(feature = "deserialize_in_place")]
+impl<'a> DeTypeGenerics<'a> {
+    fn in_place(self) -> InPlaceTypeGenerics<'a> {
+        InPlaceTypeGenerics(self.0)
+    }
+}
+
+#[cfg(feature = "deserialize_in_place")]
+fn place_lifetime() -> syn::LifetimeDef {
+    syn::LifetimeDef {
+        attrs: Vec::new(),
+        lifetime: syn::Lifetime::new("'place", Span::call_site()),
+        colon_token: None,
+        bounds: Punctuated::new(),
+    }
+}
+
+fn split_with_de_lifetime(
+    params: &Parameters,
+) -> (
+    DeImplGenerics,
+    DeTypeGenerics,
+    syn::TypeGenerics,
+    Option<&syn::WhereClause>,
+) {
+    let de_impl_generics = DeImplGenerics(params);
+    let de_ty_generics = DeTypeGenerics(params);
+    let (_, ty_generics, where_clause) = params.generics.split_for_impl();
+    (de_impl_generics, de_ty_generics, ty_generics, where_clause)
+}