Deleted vendor folder

1 files changed, 0 insertions, 1881 deletions

diff --git a/vendor/serde_derive/src/internals/attr.rs b/vendor/serde_derive/src/internals/attr.rs
deleted file mode 100644
index bb9de32..0000000
--- a/vendor/serde_derive/src/internals/attr.rs
+++ /dev/null
@@ -1,1881 +0,0 @@
-use crate::internals::symbol::*;
-use crate::internals::{ungroup, Ctxt};
-use proc_macro2::{Spacing, Span, TokenStream, TokenTree};
-use quote::ToTokens;
-use std::borrow::Cow;
-use std::collections::BTreeSet;
-use std::iter::FromIterator;
-use syn::meta::ParseNestedMeta;
-use syn::parse::ParseStream;
-use syn::punctuated::Punctuated;
-use syn::{parse_quote, token, Ident, Lifetime, Token};
-
-// This module handles parsing of `#[serde(...)]` attributes. The entrypoints
-// are `attr::Container::from_ast`, `attr::Variant::from_ast`, and
-// `attr::Field::from_ast`. Each returns an instance of the corresponding
-// struct. Note that none of them return a Result. Unrecognized, malformed, or
-// duplicated attributes result in a span_err but otherwise are ignored. The
-// user will see errors simultaneously for all bad attributes in the crate
-// rather than just the first.
-
-pub use crate::internals::case::RenameRule;
-
-struct Attr<'c, T> {
-    cx: &'c Ctxt,
-    name: Symbol,
-    tokens: TokenStream,
-    value: Option<T>,
-}
-
-impl<'c, T> Attr<'c, T> {
-    fn none(cx: &'c Ctxt, name: Symbol) -> Self {
-        Attr {
-            cx,
-            name,
-            tokens: TokenStream::new(),
-            value: None,
-        }
-    }
-
-    fn set<A: ToTokens>(&mut self, obj: A, value: T) {
-        let tokens = obj.into_token_stream();
-
-        if self.value.is_some() {
-            let msg = format!("duplicate serde attribute `{}`", self.name);
-            self.cx.error_spanned_by(tokens, msg);
-        } else {
-            self.tokens = tokens;
-            self.value = Some(value);
-        }
-    }
-
-    fn set_opt<A: ToTokens>(&mut self, obj: A, value: Option<T>) {
-        if let Some(value) = value {
-            self.set(obj, value);
-        }
-    }
-
-    fn set_if_none(&mut self, value: T) {
-        if self.value.is_none() {
-            self.value = Some(value);
-        }
-    }
-
-    fn get(self) -> Option<T> {
-        self.value
-    }
-
-    fn get_with_tokens(self) -> Option<(TokenStream, T)> {
-        match self.value {
-            Some(v) => Some((self.tokens, v)),
-            None => None,
-        }
-    }
-}
-
-struct BoolAttr<'c>(Attr<'c, ()>);
-
-impl<'c> BoolAttr<'c> {
-    fn none(cx: &'c Ctxt, name: Symbol) -> Self {
-        BoolAttr(Attr::none(cx, name))
-    }
-
-    fn set_true<A: ToTokens>(&mut self, obj: A) {
-        self.0.set(obj, ());
-    }
-
-    fn get(&self) -> bool {
-        self.0.value.is_some()
-    }
-}
-
-struct VecAttr<'c, T> {
-    cx: &'c Ctxt,
-    name: Symbol,
-    first_dup_tokens: TokenStream,
-    values: Vec<T>,
-}
-
-impl<'c, T> VecAttr<'c, T> {
-    fn none(cx: &'c Ctxt, name: Symbol) -> Self {
-        VecAttr {
-            cx,
-            name,
-            first_dup_tokens: TokenStream::new(),
-            values: Vec::new(),
-        }
-    }
-
-    fn insert<A: ToTokens>(&mut self, obj: A, value: T) {
-        if self.values.len() == 1 {
-            self.first_dup_tokens = obj.into_token_stream();
-        }
-        self.values.push(value);
-    }
-
-    fn at_most_one(mut self) -> Option<T> {
-        if self.values.len() > 1 {
-            let dup_token = self.first_dup_tokens;
-            let msg = format!("duplicate serde attribute `{}`", self.name);
-            self.cx.error_spanned_by(dup_token, msg);
-            None
-        } else {
-            self.values.pop()
-        }
-    }
-
-    fn get(self) -> Vec<T> {
-        self.values
-    }
-}
-
-pub struct Name {
-    serialize: String,
-    serialize_renamed: bool,
-    deserialize: String,
-    deserialize_renamed: bool,
-    deserialize_aliases: BTreeSet<String>,
-}
-
-fn unraw(ident: &Ident) -> String {
-    ident.to_string().trim_start_matches("r#").to_owned()
-}
-
-impl Name {
-    fn from_attrs(
-        source_name: String,
-        ser_name: Attr<String>,
-        de_name: Attr<String>,
-        de_aliases: Option<VecAttr<String>>,
-    ) -> Name {
-        let mut alias_set = BTreeSet::new();
-        if let Some(de_aliases) = de_aliases {
-            for alias_name in de_aliases.get() {
-                alias_set.insert(alias_name);
-            }
-        }
-
-        let ser_name = ser_name.get();
-        let ser_renamed = ser_name.is_some();
-        let de_name = de_name.get();
-        let de_renamed = de_name.is_some();
-        Name {
-            serialize: ser_name.unwrap_or_else(|| source_name.clone()),
-            serialize_renamed: ser_renamed,
-            deserialize: de_name.unwrap_or(source_name),
-            deserialize_renamed: de_renamed,
-            deserialize_aliases: alias_set,
-        }
-    }
-
-    /// Return the container name for the container when serializing.
-    pub fn serialize_name(&self) -> &str {
-        &self.serialize
-    }
-
-    /// Return the container name for the container when deserializing.
-    pub fn deserialize_name(&self) -> &str {
-        &self.deserialize
-    }
-
-    fn deserialize_aliases(&self) -> &BTreeSet<String> {
-        &self.deserialize_aliases
-    }
-}
-
-#[derive(Copy, Clone)]
-pub struct RenameAllRules {
-    serialize: RenameRule,
-    deserialize: RenameRule,
-}
-
-impl RenameAllRules {
-    /// Returns a new `RenameAllRules` with the individual rules of `self` and
-    /// `other_rules` joined by `RenameRules::or`.
-    pub fn or(self, other_rules: Self) -> Self {
-        Self {
-            serialize: self.serialize.or(other_rules.serialize),
-            deserialize: self.deserialize.or(other_rules.deserialize),
-        }
-    }
-}
-
-/// Represents struct or enum attribute information.
-pub struct Container {
-    name: Name,
-    transparent: bool,
-    deny_unknown_fields: bool,
-    default: Default,
-    rename_all_rules: RenameAllRules,
-    rename_all_fields_rules: RenameAllRules,
-    ser_bound: Option<Vec<syn::WherePredicate>>,
-    de_bound: Option<Vec<syn::WherePredicate>>,
-    tag: TagType,
-    type_from: Option<syn::Type>,
-    type_try_from: Option<syn::Type>,
-    type_into: Option<syn::Type>,
-    remote: Option<syn::Path>,
-    identifier: Identifier,
-    has_flatten: bool,
-    serde_path: Option<syn::Path>,
-    is_packed: bool,
-    /// Error message generated when type can't be deserialized
-    expecting: Option<String>,
-    non_exhaustive: bool,
-}
-
-/// Styles of representing an enum.
-pub enum TagType {
-    /// The default.
-    ///
-    /// ```json
-    /// {"variant1": {"key1": "value1", "key2": "value2"}}
-    /// ```
-    External,
-
-    /// `#[serde(tag = "type")]`
-    ///
-    /// ```json
-    /// {"type": "variant1", "key1": "value1", "key2": "value2"}
-    /// ```
-    Internal { tag: String },
-
-    /// `#[serde(tag = "t", content = "c")]`
-    ///
-    /// ```json
-    /// {"t": "variant1", "c": {"key1": "value1", "key2": "value2"}}
-    /// ```
-    Adjacent { tag: String, content: String },
-
-    /// `#[serde(untagged)]`
-    ///
-    /// ```json
-    /// {"key1": "value1", "key2": "value2"}
-    /// ```
-    None,
-}
-
-/// Whether this enum represents the fields of a struct or the variants of an
-/// enum.
-#[derive(Copy, Clone)]
-pub enum Identifier {
-    /// It does not.
-    No,
-
-    /// This enum represents the fields of a struct. All of the variants must be
-    /// unit variants, except possibly one which is annotated with
-    /// `#[serde(other)]` and is a newtype variant.
-    Field,
-
-    /// This enum represents the variants of an enum. All of the variants must
-    /// be unit variants.
-    Variant,
-}
-
-impl Identifier {
-    #[cfg(feature = "deserialize_in_place")]
-    pub fn is_some(self) -> bool {
-        match self {
-            Identifier::No => false,
-            Identifier::Field | Identifier::Variant => true,
-        }
-    }
-}
-
-impl Container {
-    /// Extract out the `#[serde(...)]` attributes from an item.
-    pub fn from_ast(cx: &Ctxt, item: &syn::DeriveInput) -> Self {
-        let mut ser_name = Attr::none(cx, RENAME);
-        let mut de_name = Attr::none(cx, RENAME);
-        let mut transparent = BoolAttr::none(cx, TRANSPARENT);
-        let mut deny_unknown_fields = BoolAttr::none(cx, DENY_UNKNOWN_FIELDS);
-        let mut default = Attr::none(cx, DEFAULT);
-        let mut rename_all_ser_rule = Attr::none(cx, RENAME_ALL);
-        let mut rename_all_de_rule = Attr::none(cx, RENAME_ALL);
-        let mut rename_all_fields_ser_rule = Attr::none(cx, RENAME_ALL_FIELDS);
-        let mut rename_all_fields_de_rule = Attr::none(cx, RENAME_ALL_FIELDS);
-        let mut ser_bound = Attr::none(cx, BOUND);
-        let mut de_bound = Attr::none(cx, BOUND);
-        let mut untagged = BoolAttr::none(cx, UNTAGGED);
-        let mut internal_tag = Attr::none(cx, TAG);
-        let mut content = Attr::none(cx, CONTENT);
-        let mut type_from = Attr::none(cx, FROM);
-        let mut type_try_from = Attr::none(cx, TRY_FROM);
-        let mut type_into = Attr::none(cx, INTO);
-        let mut remote = Attr::none(cx, REMOTE);
-        let mut field_identifier = BoolAttr::none(cx, FIELD_IDENTIFIER);
-        let mut variant_identifier = BoolAttr::none(cx, VARIANT_IDENTIFIER);
-        let mut serde_path = Attr::none(cx, CRATE);
-        let mut expecting = Attr::none(cx, EXPECTING);
-        let mut non_exhaustive = false;
-
-        for attr in &item.attrs {
-            if attr.path() != SERDE {
-                non_exhaustive |=
-                    matches!(&attr.meta, syn::Meta::Path(path) if path == NON_EXHAUSTIVE);
-                continue;
-            }
-
-            if let syn::Meta::List(meta) = &attr.meta {
-                if meta.tokens.is_empty() {
-                    continue;
-                }
-            }
-
-            if let Err(err) = attr.parse_nested_meta(|meta| {
-                if meta.path == RENAME {
-                    // #[serde(rename = "foo")]
-                    // #[serde(rename(serialize = "foo", deserialize = "bar"))]
-                    let (ser, de) = get_renames(cx, RENAME, &meta)?;
-                    ser_name.set_opt(&meta.path, ser.as_ref().map(syn::LitStr::value));
-                    de_name.set_opt(&meta.path, de.as_ref().map(syn::LitStr::value));
-                } else if meta.path == RENAME_ALL {
-                    // #[serde(rename_all = "foo")]
-                    // #[serde(rename_all(serialize = "foo", deserialize = "bar"))]
-                    let one_name = meta.input.peek(Token![=]);
-                    let (ser, de) = get_renames(cx, RENAME_ALL, &meta)?;
-                    if let Some(ser) = ser {
-                        match RenameRule::from_str(&ser.value()) {
-                            Ok(rename_rule) => rename_all_ser_rule.set(&meta.path, rename_rule),
-                            Err(err) => cx.error_spanned_by(ser, err),
-                        }
-                    }
-                    if let Some(de) = de {
-                        match RenameRule::from_str(&de.value()) {
-                            Ok(rename_rule) => rename_all_de_rule.set(&meta.path, rename_rule),
-                            Err(err) => {
-                                if !one_name {
-                                    cx.error_spanned_by(de, err);
-                                }
-                            }
-                        }
-                    }
-                } else if meta.path == RENAME_ALL_FIELDS {
-                    // #[serde(rename_all_fields = "foo")]
-                    // #[serde(rename_all_fields(serialize = "foo", deserialize = "bar"))]
-                    let one_name = meta.input.peek(Token![=]);
-                    let (ser, de) = get_renames(cx, RENAME_ALL_FIELDS, &meta)?;
-
-                    match item.data {
-                        syn::Data::Enum(_) => {
-                            if let Some(ser) = ser {
-                                match RenameRule::from_str(&ser.value()) {
-                                    Ok(rename_rule) => {
-                                        rename_all_fields_ser_rule.set(&meta.path, rename_rule);
-                                    }
-                                    Err(err) => cx.error_spanned_by(ser, err),
-                                }
-                            }
-                            if let Some(de) = de {
-                                match RenameRule::from_str(&de.value()) {
-                                    Ok(rename_rule) => {
-                                        rename_all_fields_de_rule.set(&meta.path, rename_rule);
-                                    }
-                                    Err(err) => {
-                                        if !one_name {
-                                            cx.error_spanned_by(de, err);
-                                        }
-                                    }
-                                }
-                            }
-                        }
-                        syn::Data::Struct(_) => {
-                            let msg = "#[serde(rename_all_fields)] can only be used on enums";
-                            cx.syn_error(meta.error(msg));
-                        }
-                        syn::Data::Union(_) => {
-                            let msg = "#[serde(rename_all_fields)] can only be used on enums";
-                            cx.syn_error(meta.error(msg));
-                        }
-                    }
-                } else if meta.path == TRANSPARENT {
-                    // #[serde(transparent)]
-                    transparent.set_true(meta.path);
-                } else if meta.path == DENY_UNKNOWN_FIELDS {
-                    // #[serde(deny_unknown_fields)]
-                    deny_unknown_fields.set_true(meta.path);
-                } else if meta.path == DEFAULT {
-                    if meta.input.peek(Token![=]) {
-                        // #[serde(default = "...")]
-                        if let Some(path) = parse_lit_into_expr_path(cx, DEFAULT, &meta)? {
-                            match &item.data {
-                                syn::Data::Struct(syn::DataStruct { fields, .. }) => match fields {
-                                    syn::Fields::Named(_) | syn::Fields::Unnamed(_) => {
-                                        default.set(&meta.path, Default::Path(path));
-                                    }
-                                    syn::Fields::Unit => {
-                                        let msg = "#[serde(default = \"...\")] can only be used on structs that have fields";
-                                        cx.syn_error(meta.error(msg));
-                                    }
-                                },
-                                syn::Data::Enum(_) => {
-                                    let msg = "#[serde(default = \"...\")] can only be used on structs";
-                                    cx.syn_error(meta.error(msg));
-                                }
-                                syn::Data::Union(_) => {
-                                    let msg = "#[serde(default = \"...\")] can only be used on structs";
-                                    cx.syn_error(meta.error(msg));
-                                }
-                            }
-                        }
-                    } else {
-                        // #[serde(default)]
-                        match &item.data {
-                            syn::Data::Struct(syn::DataStruct { fields, .. }) => match fields {
-                                syn::Fields::Named(_) | syn::Fields::Unnamed(_) => {
-                                    default.set(meta.path, Default::Default);
-                                }
-                                syn::Fields::Unit => {
-                                    let msg = "#[serde(default)] can only be used on structs that have fields";
-                                    cx.error_spanned_by(fields, msg);
-                                }
-                            },
-                            syn::Data::Enum(_) => {
-                                let msg = "#[serde(default)] can only be used on structs";
-                                cx.syn_error(meta.error(msg));
-                            }
-                            syn::Data::Union(_) => {
-                                let msg = "#[serde(default)] can only be used on structs";
-                                cx.syn_error(meta.error(msg));
-                            }
-                        }
-                    }
-                } else if meta.path == BOUND {
-                    // #[serde(bound = "T: SomeBound")]
-                    // #[serde(bound(serialize = "...", deserialize = "..."))]
-                    let (ser, de) = get_where_predicates(cx, &meta)?;
-                    ser_bound.set_opt(&meta.path, ser);
-                    de_bound.set_opt(&meta.path, de);
-                } else if meta.path == UNTAGGED {
-                    // #[serde(untagged)]
-                    match item.data {
-                        syn::Data::Enum(_) => {
-                            untagged.set_true(&meta.path);
-                        }
-                        syn::Data::Struct(_) => {
-                            let msg = "#[serde(untagged)] can only be used on enums";
-                            cx.syn_error(meta.error(msg));
-                        }
-                        syn::Data::Union(_) => {
-                            let msg = "#[serde(untagged)] can only be used on enums";
-                            cx.syn_error(meta.error(msg));
-                        }
-                    }
-                } else if meta.path == TAG {
-                    // #[serde(tag = "type")]
-                    if let Some(s) = get_lit_str(cx, TAG, &meta)? {
-                        match &item.data {
-                            syn::Data::Enum(_) => {
-                                internal_tag.set(&meta.path, s.value());
-                            }
-                            syn::Data::Struct(syn::DataStruct { fields, .. }) => match fields {
-                                syn::Fields::Named(_) => {
-                                    internal_tag.set(&meta.path, s.value());
-                                }
-                                syn::Fields::Unnamed(_) | syn::Fields::Unit => {
-                                    let msg = "#[serde(tag = \"...\")] can only be used on enums and structs with named fields";
-                                    cx.syn_error(meta.error(msg));
-                                }
-                            },
-                            syn::Data::Union(_) => {
-                                let msg = "#[serde(tag = \"...\")] can only be used on enums and structs with named fields";
-                                cx.syn_error(meta.error(msg));
-                            }
-                        }
-                    }
-                } else if meta.path == CONTENT {
-                    // #[serde(content = "c")]
-                    if let Some(s) = get_lit_str(cx, CONTENT, &meta)? {
-                        match &item.data {
-                            syn::Data::Enum(_) => {
-                                content.set(&meta.path, s.value());
-                            }
-                            syn::Data::Struct(_) => {
-                                let msg = "#[serde(content = \"...\")] can only be used on enums";
-                                cx.syn_error(meta.error(msg));
-                            }
-                            syn::Data::Union(_) => {
-                                let msg = "#[serde(content = \"...\")] can only be used on enums";
-                                cx.syn_error(meta.error(msg));
-                            }
-                        }
-                    }
-                } else if meta.path == FROM {
-                    // #[serde(from = "Type")]
-                    if let Some(from_ty) = parse_lit_into_ty(cx, FROM, &meta)? {
-                        type_from.set_opt(&meta.path, Some(from_ty));
-                    }
-                } else if meta.path == TRY_FROM {
-                    // #[serde(try_from = "Type")]
-                    if let Some(try_from_ty) = parse_lit_into_ty(cx, TRY_FROM, &meta)? {
-                        type_try_from.set_opt(&meta.path, Some(try_from_ty));
-                    }
-                } else if meta.path == INTO {
-                    // #[serde(into = "Type")]
-                    if let Some(into_ty) = parse_lit_into_ty(cx, INTO, &meta)? {
-                        type_into.set_opt(&meta.path, Some(into_ty));
-                    }
-                } else if meta.path == REMOTE {
-                    // #[serde(remote = "...")]
-                    if let Some(path) = parse_lit_into_path(cx, REMOTE, &meta)? {
-                        if is_primitive_path(&path, "Self") {
-                            remote.set(&meta.path, item.ident.clone().into());
-                        } else {
-                            remote.set(&meta.path, path);
-                        }
-                    }
-                } else if meta.path == FIELD_IDENTIFIER {
-                    // #[serde(field_identifier)]
-                    field_identifier.set_true(&meta.path);
-                } else if meta.path == VARIANT_IDENTIFIER {
-                    // #[serde(variant_identifier)]
-                    variant_identifier.set_true(&meta.path);
-                } else if meta.path == CRATE {
-                    // #[serde(crate = "foo")]
-                    if let Some(path) = parse_lit_into_path(cx, CRATE, &meta)? {
-                        serde_path.set(&meta.path, path);
-                    }
-                } else if meta.path == EXPECTING {
-                    // #[serde(expecting = "a message")]
-                    if let Some(s) = get_lit_str(cx, EXPECTING, &meta)? {
-                        expecting.set(&meta.path, s.value());
-                    }
-                } else {
-                    let path = meta.path.to_token_stream().to_string().replace(' ', "");
-                    return Err(
-                        meta.error(format_args!("unknown serde container attribute `{}`", path))
-                    );
-                }
-                Ok(())
-            }) {
-                cx.syn_error(err);
-            }
-        }
-
-        let mut is_packed = false;
-        for attr in &item.attrs {
-            if attr.path() == REPR {
-                let _ = attr.parse_args_with(|input: ParseStream| {
-                    while let Some(token) = input.parse()? {
-                        if let TokenTree::Ident(ident) = token {
-                            is_packed |= ident == "packed";
-                        }
-                    }
-                    Ok(())
-                });
-            }
-        }
-
-        Container {
-            name: Name::from_attrs(unraw(&item.ident), ser_name, de_name, None),
-            transparent: transparent.get(),
-            deny_unknown_fields: deny_unknown_fields.get(),
-            default: default.get().unwrap_or(Default::None),
-            rename_all_rules: RenameAllRules {
-                serialize: rename_all_ser_rule.get().unwrap_or(RenameRule::None),
-                deserialize: rename_all_de_rule.get().unwrap_or(RenameRule::None),
-            },
-            rename_all_fields_rules: RenameAllRules {
-                serialize: rename_all_fields_ser_rule.get().unwrap_or(RenameRule::None),
-                deserialize: rename_all_fields_de_rule.get().unwrap_or(RenameRule::None),
-            },
-            ser_bound: ser_bound.get(),
-            de_bound: de_bound.get(),
-            tag: decide_tag(cx, item, untagged, internal_tag, content),
-            type_from: type_from.get(),
-            type_try_from: type_try_from.get(),
-            type_into: type_into.get(),
-            remote: remote.get(),
-            identifier: decide_identifier(cx, item, field_identifier, variant_identifier),
-            has_flatten: false,
-            serde_path: serde_path.get(),
-            is_packed,
-            expecting: expecting.get(),
-            non_exhaustive,
-        }
-    }
-
-    pub fn name(&self) -> &Name {
-        &self.name
-    }
-
-    pub fn rename_all_rules(&self) -> RenameAllRules {
-        self.rename_all_rules
-    }
-
-    pub fn rename_all_fields_rules(&self) -> RenameAllRules {
-        self.rename_all_fields_rules
-    }
-
-    pub fn transparent(&self) -> bool {
-        self.transparent
-    }
-
-    pub fn deny_unknown_fields(&self) -> bool {
-        self.deny_unknown_fields
-    }
-
-    pub fn default(&self) -> &Default {
-        &self.default
-    }
-
-    pub fn ser_bound(&self) -> Option<&[syn::WherePredicate]> {
-        self.ser_bound.as_ref().map(|vec| &vec[..])
-    }
-
-    pub fn de_bound(&self) -> Option<&[syn::WherePredicate]> {
-        self.de_bound.as_ref().map(|vec| &vec[..])
-    }
-
-    pub fn tag(&self) -> &TagType {
-        &self.tag
-    }
-
-    pub fn type_from(&self) -> Option<&syn::Type> {
-        self.type_from.as_ref()
-    }
-
-    pub fn type_try_from(&self) -> Option<&syn::Type> {
-        self.type_try_from.as_ref()
-    }
-
-    pub fn type_into(&self) -> Option<&syn::Type> {
-        self.type_into.as_ref()
-    }
-
-    pub fn remote(&self) -> Option<&syn::Path> {
-        self.remote.as_ref()
-    }
-
-    pub fn is_packed(&self) -> bool {
-        self.is_packed
-    }
-
-    pub fn identifier(&self) -> Identifier {
-        self.identifier
-    }
-
-    pub fn has_flatten(&self) -> bool {
-        self.has_flatten
-    }
-
-    pub fn mark_has_flatten(&mut self) {
-        self.has_flatten = true;
-    }
-
-    pub fn custom_serde_path(&self) -> Option<&syn::Path> {
-        self.serde_path.as_ref()
-    }
-
-    pub fn serde_path(&self) -> Cow<syn::Path> {
-        self.custom_serde_path()
-            .map_or_else(|| Cow::Owned(parse_quote!(_serde)), Cow::Borrowed)
-    }
-
-    /// Error message generated when type can't be deserialized.
-    /// If `None`, default message will be used
-    pub fn expecting(&self) -> Option<&str> {
-        self.expecting.as_ref().map(String::as_ref)
-    }
-
-    pub fn non_exhaustive(&self) -> bool {
-        self.non_exhaustive
-    }
-}
-
-fn decide_tag(
-    cx: &Ctxt,
-    item: &syn::DeriveInput,
-    untagged: BoolAttr,
-    internal_tag: Attr<String>,
-    content: Attr<String>,
-) -> TagType {
-    match (
-        untagged.0.get_with_tokens(),
-        internal_tag.get_with_tokens(),
-        content.get_with_tokens(),
-    ) {
-        (None, None, None) => TagType::External,
-        (Some(_), None, None) => TagType::None,
-        (None, Some((_, tag)), None) => {
-            // Check that there are no tuple variants.
-            if let syn::Data::Enum(data) = &item.data {
-                for variant in &data.variants {
-                    match &variant.fields {
-                        syn::Fields::Named(_) | syn::Fields::Unit => {}
-                        syn::Fields::Unnamed(fields) => {
-                            if fields.unnamed.len() != 1 {
-                                let msg =
-                                    "#[serde(tag = \"...\")] cannot be used with tuple variants";
-                                cx.error_spanned_by(variant, msg);
-                                break;
-                            }
-                        }
-                    }
-                }
-            }
-            TagType::Internal { tag }
-        }
-        (Some((untagged_tokens, ())), Some((tag_tokens, _)), None) => {
-            let msg = "enum cannot be both untagged and internally tagged";
-            cx.error_spanned_by(untagged_tokens, msg);
-            cx.error_spanned_by(tag_tokens, msg);
-            TagType::External // doesn't matter, will error
-        }
-        (None, None, Some((content_tokens, _))) => {
-            let msg = "#[serde(tag = \"...\", content = \"...\")] must be used together";
-            cx.error_spanned_by(content_tokens, msg);
-            TagType::External
-        }
-        (Some((untagged_tokens, ())), None, Some((content_tokens, _))) => {
-            let msg = "untagged enum cannot have #[serde(content = \"...\")]";
-            cx.error_spanned_by(untagged_tokens, msg);
-            cx.error_spanned_by(content_tokens, msg);
-            TagType::External
-        }
-        (None, Some((_, tag)), Some((_, content))) => TagType::Adjacent { tag, content },
-        (Some((untagged_tokens, ())), Some((tag_tokens, _)), Some((content_tokens, _))) => {
-            let msg = "untagged enum cannot have #[serde(tag = \"...\", content = \"...\")]";
-            cx.error_spanned_by(untagged_tokens, msg);
-            cx.error_spanned_by(tag_tokens, msg);
-            cx.error_spanned_by(content_tokens, msg);
-            TagType::External
-        }
-    }
-}
-
-fn decide_identifier(
-    cx: &Ctxt,
-    item: &syn::DeriveInput,
-    field_identifier: BoolAttr,
-    variant_identifier: BoolAttr,
-) -> Identifier {
-    match (
-        &item.data,
-        field_identifier.0.get_with_tokens(),
-        variant_identifier.0.get_with_tokens(),
-    ) {
-        (_, None, None) => Identifier::No,
-        (_, Some((field_identifier_tokens, ())), Some((variant_identifier_tokens, ()))) => {
-            let msg =
-                "#[serde(field_identifier)] and #[serde(variant_identifier)] cannot both be set";
-            cx.error_spanned_by(field_identifier_tokens, msg);
-            cx.error_spanned_by(variant_identifier_tokens, msg);
-            Identifier::No
-        }
-        (syn::Data::Enum(_), Some(_), None) => Identifier::Field,
-        (syn::Data::Enum(_), None, Some(_)) => Identifier::Variant,
-        (syn::Data::Struct(syn::DataStruct { struct_token, .. }), Some(_), None) => {
-            let msg = "#[serde(field_identifier)] can only be used on an enum";
-            cx.error_spanned_by(struct_token, msg);
-            Identifier::No
-        }
-        (syn::Data::Union(syn::DataUnion { union_token, .. }), Some(_), None) => {
-            let msg = "#[serde(field_identifier)] can only be used on an enum";
-            cx.error_spanned_by(union_token, msg);
-            Identifier::No
-        }
-        (syn::Data::Struct(syn::DataStruct { struct_token, .. }), None, Some(_)) => {
-            let msg = "#[serde(variant_identifier)] can only be used on an enum";
-            cx.error_spanned_by(struct_token, msg);
-            Identifier::No
-        }
-        (syn::Data::Union(syn::DataUnion { union_token, .. }), None, Some(_)) => {
-            let msg = "#[serde(variant_identifier)] can only be used on an enum";
-            cx.error_spanned_by(union_token, msg);
-            Identifier::No
-        }
-    }
-}
-
-/// Represents variant attribute information
-pub struct Variant {
-    name: Name,
-    rename_all_rules: RenameAllRules,
-    ser_bound: Option<Vec<syn::WherePredicate>>,
-    de_bound: Option<Vec<syn::WherePredicate>>,
-    skip_deserializing: bool,
-    skip_serializing: bool,
-    other: bool,
-    serialize_with: Option<syn::ExprPath>,
-    deserialize_with: Option<syn::ExprPath>,
-    borrow: Option<BorrowAttribute>,
-    untagged: bool,
-}
-
-struct BorrowAttribute {
-    path: syn::Path,
-    lifetimes: Option<BTreeSet<syn::Lifetime>>,
-}
-
-impl Variant {
-    pub fn from_ast(cx: &Ctxt, variant: &syn::Variant) -> Self {
-        let mut ser_name = Attr::none(cx, RENAME);
-        let mut de_name = Attr::none(cx, RENAME);
-        let mut de_aliases = VecAttr::none(cx, RENAME);
-        let mut skip_deserializing = BoolAttr::none(cx, SKIP_DESERIALIZING);
-        let mut skip_serializing = BoolAttr::none(cx, SKIP_SERIALIZING);
-        let mut rename_all_ser_rule = Attr::none(cx, RENAME_ALL);
-        let mut rename_all_de_rule = Attr::none(cx, RENAME_ALL);
-        let mut ser_bound = Attr::none(cx, BOUND);
-        let mut de_bound = Attr::none(cx, BOUND);
-        let mut other = BoolAttr::none(cx, OTHER);
-        let mut serialize_with = Attr::none(cx, SERIALIZE_WITH);
-        let mut deserialize_with = Attr::none(cx, DESERIALIZE_WITH);
-        let mut borrow = Attr::none(cx, BORROW);
-        let mut untagged = BoolAttr::none(cx, UNTAGGED);
-
-        for attr in &variant.attrs {
-            if attr.path() != SERDE {
-                continue;
-            }
-
-            if let syn::Meta::List(meta) = &attr.meta {
-                if meta.tokens.is_empty() {
-                    continue;
-                }
-            }
-
-            if let Err(err) = attr.parse_nested_meta(|meta| {
-                if meta.path == RENAME {
-                    // #[serde(rename = "foo")]
-                    // #[serde(rename(serialize = "foo", deserialize = "bar"))]
-                    let (ser, de) = get_multiple_renames(cx, &meta)?;
-                    ser_name.set_opt(&meta.path, ser.as_ref().map(syn::LitStr::value));
-                    for de_value in de {
-                        de_name.set_if_none(de_value.value());
-                        de_aliases.insert(&meta.path, de_value.value());
-                    }
-                } else if meta.path == ALIAS {
-                    // #[serde(alias = "foo")]
-                    if let Some(s) = get_lit_str(cx, ALIAS, &meta)? {
-                        de_aliases.insert(&meta.path, s.value());
-                    }
-                } else if meta.path == RENAME_ALL {
-                    // #[serde(rename_all = "foo")]
-                    // #[serde(rename_all(serialize = "foo", deserialize = "bar"))]
-                    let one_name = meta.input.peek(Token![=]);
-                    let (ser, de) = get_renames(cx, RENAME_ALL, &meta)?;
-                    if let Some(ser) = ser {
-                        match RenameRule::from_str(&ser.value()) {
-                            Ok(rename_rule) => rename_all_ser_rule.set(&meta.path, rename_rule),
-                            Err(err) => cx.error_spanned_by(ser, err),
-                        }
-                    }
-                    if let Some(de) = de {
-                        match RenameRule::from_str(&de.value()) {
-                            Ok(rename_rule) => rename_all_de_rule.set(&meta.path, rename_rule),
-                            Err(err) => {
-                                if !one_name {
-                                    cx.error_spanned_by(de, err);
-                                }
-                            }
-                        }
-                    }
-                } else if meta.path == SKIP {
-                    // #[serde(skip)]
-                    skip_serializing.set_true(&meta.path);
-                    skip_deserializing.set_true(&meta.path);
-                } else if meta.path == SKIP_DESERIALIZING {
-                    // #[serde(skip_deserializing)]
-                    skip_deserializing.set_true(&meta.path);
-                } else if meta.path == SKIP_SERIALIZING {
-                    // #[serde(skip_serializing)]
-                    skip_serializing.set_true(&meta.path);
-                } else if meta.path == OTHER {
-                    // #[serde(other)]
-                    other.set_true(&meta.path);
-                } else if meta.path == BOUND {
-                    // #[serde(bound = "T: SomeBound")]
-                    // #[serde(bound(serialize = "...", deserialize = "..."))]
-                    let (ser, de) = get_where_predicates(cx, &meta)?;
-                    ser_bound.set_opt(&meta.path, ser);
-                    de_bound.set_opt(&meta.path, de);
-                } else if meta.path == WITH {
-                    // #[serde(with = "...")]
-                    if let Some(path) = parse_lit_into_expr_path(cx, WITH, &meta)? {
-                        let mut ser_path = path.clone();
-                        ser_path
-                            .path
-                            .segments
-                            .push(Ident::new("serialize", Span::call_site()).into());
-                        serialize_with.set(&meta.path, ser_path);
-                        let mut de_path = path;
-                        de_path
-                            .path
-                            .segments
-                            .push(Ident::new("deserialize", Span::call_site()).into());
-                        deserialize_with.set(&meta.path, de_path);
-                    }
-                } else if meta.path == SERIALIZE_WITH {
-                    // #[serde(serialize_with = "...")]
-                    if let Some(path) = parse_lit_into_expr_path(cx, SERIALIZE_WITH, &meta)? {
-                        serialize_with.set(&meta.path, path);
-                    }
-                } else if meta.path == DESERIALIZE_WITH {
-                    // #[serde(deserialize_with = "...")]
-                    if let Some(path) = parse_lit_into_expr_path(cx, DESERIALIZE_WITH, &meta)? {
-                        deserialize_with.set(&meta.path, path);
-                    }
-                } else if meta.path == BORROW {
-                    let borrow_attribute = if meta.input.peek(Token![=]) {
-                        // #[serde(borrow = "'a + 'b")]
-                        let lifetimes = parse_lit_into_lifetimes(cx, &meta)?;
-                        BorrowAttribute {
-                            path: meta.path.clone(),
-                            lifetimes: Some(lifetimes),
-                        }
-                    } else {
-                        // #[serde(borrow)]
-                        BorrowAttribute {
-                            path: meta.path.clone(),
-                            lifetimes: None,
-                        }
-                    };
-                    match &variant.fields {
-                        syn::Fields::Unnamed(fields) if fields.unnamed.len() == 1 => {
-                            borrow.set(&meta.path, borrow_attribute);
-                        }
-                        _ => {
-                            let msg = "#[serde(borrow)] may only be used on newtype variants";
-                            cx.error_spanned_by(variant, msg);
-                        }
-                    }
-                } else if meta.path == UNTAGGED {
-                    untagged.set_true(&meta.path);
-                } else {
-                    let path = meta.path.to_token_stream().to_string().replace(' ', "");
-                    return Err(
-                        meta.error(format_args!("unknown serde variant attribute `{}`", path))
-                    );
-                }
-                Ok(())
-            }) {
-                cx.syn_error(err);
-            }
-        }
-
-        Variant {
-            name: Name::from_attrs(unraw(&variant.ident), ser_name, de_name, Some(de_aliases)),
-            rename_all_rules: RenameAllRules {
-                serialize: rename_all_ser_rule.get().unwrap_or(RenameRule::None),
-                deserialize: rename_all_de_rule.get().unwrap_or(RenameRule::None),
-            },
-            ser_bound: ser_bound.get(),
-            de_bound: de_bound.get(),
-            skip_deserializing: skip_deserializing.get(),
-            skip_serializing: skip_serializing.get(),
-            other: other.get(),
-            serialize_with: serialize_with.get(),
-            deserialize_with: deserialize_with.get(),
-            borrow: borrow.get(),
-            untagged: untagged.get(),
-        }
-    }
-
-    pub fn name(&self) -> &Name {
-        &self.name
-    }
-
-    pub fn aliases(&self) -> &BTreeSet<String> {
-        self.name.deserialize_aliases()
-    }
-
-    pub fn rename_by_rules(&mut self, rules: RenameAllRules) {
-        if !self.name.serialize_renamed {
-            self.name.serialize = rules.serialize.apply_to_variant(&self.name.serialize);
-        }
-        if !self.name.deserialize_renamed {
-            self.name.deserialize = rules.deserialize.apply_to_variant(&self.name.deserialize);
-        }
-        self.name
-            .deserialize_aliases
-            .insert(self.name.deserialize.clone());
-    }
-
-    pub fn rename_all_rules(&self) -> RenameAllRules {
-        self.rename_all_rules
-    }
-
-    pub fn ser_bound(&self) -> Option<&[syn::WherePredicate]> {
-        self.ser_bound.as_ref().map(|vec| &vec[..])
-    }
-
-    pub fn de_bound(&self) -> Option<&[syn::WherePredicate]> {
-        self.de_bound.as_ref().map(|vec| &vec[..])
-    }
-
-    pub fn skip_deserializing(&self) -> bool {
-        self.skip_deserializing
-    }
-
-    pub fn skip_serializing(&self) -> bool {
-        self.skip_serializing
-    }
-
-    pub fn other(&self) -> bool {
-        self.other
-    }
-
-    pub fn serialize_with(&self) -> Option<&syn::ExprPath> {
-        self.serialize_with.as_ref()
-    }
-
-    pub fn deserialize_with(&self) -> Option<&syn::ExprPath> {
-        self.deserialize_with.as_ref()
-    }
-
-    pub fn untagged(&self) -> bool {
-        self.untagged
-    }
-}
-
-/// Represents field attribute information
-pub struct Field {
-    name: Name,
-    skip_serializing: bool,
-    skip_deserializing: bool,
-    skip_serializing_if: Option<syn::ExprPath>,
-    default: Default,
-    serialize_with: Option<syn::ExprPath>,
-    deserialize_with: Option<syn::ExprPath>,
-    ser_bound: Option<Vec<syn::WherePredicate>>,
-    de_bound: Option<Vec<syn::WherePredicate>>,
-    borrowed_lifetimes: BTreeSet<syn::Lifetime>,
-    getter: Option<syn::ExprPath>,
-    flatten: bool,
-    transparent: bool,
-}
-
-/// Represents the default to use for a field when deserializing.
-pub enum Default {
-    /// Field must always be specified because it does not have a default.
-    None,
-    /// The default is given by `std::default::Default::default()`.
-    Default,
-    /// The default is given by this function.
-    Path(syn::ExprPath),
-}
-
-impl Default {
-    pub fn is_none(&self) -> bool {
-        match self {
-            Default::None => true,
-            Default::Default | Default::Path(_) => false,
-        }
-    }
-}
-
-impl Field {
-    /// Extract out the `#[serde(...)]` attributes from a struct field.
-    pub fn from_ast(
-        cx: &Ctxt,
-        index: usize,
-        field: &syn::Field,
-        attrs: Option<&Variant>,
-        container_default: &Default,
-    ) -> Self {
-        let mut ser_name = Attr::none(cx, RENAME);
-        let mut de_name = Attr::none(cx, RENAME);
-        let mut de_aliases = VecAttr::none(cx, RENAME);
-        let mut skip_serializing = BoolAttr::none(cx, SKIP_SERIALIZING);
-        let mut skip_deserializing = BoolAttr::none(cx, SKIP_DESERIALIZING);
-        let mut skip_serializing_if = Attr::none(cx, SKIP_SERIALIZING_IF);
-        let mut default = Attr::none(cx, DEFAULT);
-        let mut serialize_with = Attr::none(cx, SERIALIZE_WITH);
-        let mut deserialize_with = Attr::none(cx, DESERIALIZE_WITH);
-        let mut ser_bound = Attr::none(cx, BOUND);
-        let mut de_bound = Attr::none(cx, BOUND);
-        let mut borrowed_lifetimes = Attr::none(cx, BORROW);
-        let mut getter = Attr::none(cx, GETTER);
-        let mut flatten = BoolAttr::none(cx, FLATTEN);
-
-        let ident = match &field.ident {
-            Some(ident) => unraw(ident),
-            None => index.to_string(),
-        };
-
-        if let Some(borrow_attribute) = attrs.and_then(|variant| variant.borrow.as_ref()) {
-            if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, field) {
-                if let Some(lifetimes) = &borrow_attribute.lifetimes {
-                    for lifetime in lifetimes {
-                        if !borrowable.contains(lifetime) {
-                            let msg =
-                                format!("field `{}` does not have lifetime {}", ident, lifetime);
-                            cx.error_spanned_by(field, msg);
-                        }
-                    }
-                    borrowed_lifetimes.set(&borrow_attribute.path, lifetimes.clone());
-                } else {
-                    borrowed_lifetimes.set(&borrow_attribute.path, borrowable);
-                }
-            }
-        }
-
-        for attr in &field.attrs {
-            if attr.path() != SERDE {
-                continue;
-            }
-
-            if let syn::Meta::List(meta) = &attr.meta {
-                if meta.tokens.is_empty() {
-                    continue;
-                }
-            }
-
-            if let Err(err) = attr.parse_nested_meta(|meta| {
-                if meta.path == RENAME {
-                    // #[serde(rename = "foo")]
-                    // #[serde(rename(serialize = "foo", deserialize = "bar"))]
-                    let (ser, de) = get_multiple_renames(cx, &meta)?;
-                    ser_name.set_opt(&meta.path, ser.as_ref().map(syn::LitStr::value));
-                    for de_value in de {
-                        de_name.set_if_none(de_value.value());
-                        de_aliases.insert(&meta.path, de_value.value());
-                    }
-                } else if meta.path == ALIAS {
-                    // #[serde(alias = "foo")]
-                    if let Some(s) = get_lit_str(cx, ALIAS, &meta)? {
-                        de_aliases.insert(&meta.path, s.value());
-                    }
-                } else if meta.path == DEFAULT {
-                    if meta.input.peek(Token![=]) {
-                        // #[serde(default = "...")]
-                        if let Some(path) = parse_lit_into_expr_path(cx, DEFAULT, &meta)? {
-                            default.set(&meta.path, Default::Path(path));
-                        }
-                    } else {
-                        // #[serde(default)]
-                        default.set(&meta.path, Default::Default);
-                    }
-                } else if meta.path == SKIP_SERIALIZING {
-                    // #[serde(skip_serializing)]
-                    skip_serializing.set_true(&meta.path);
-                } else if meta.path == SKIP_DESERIALIZING {
-                    // #[serde(skip_deserializing)]
-                    skip_deserializing.set_true(&meta.path);
-                } else if meta.path == SKIP {
-                    // #[serde(skip)]
-                    skip_serializing.set_true(&meta.path);
-                    skip_deserializing.set_true(&meta.path);
-                } else if meta.path == SKIP_SERIALIZING_IF {
-                    // #[serde(skip_serializing_if = "...")]
-                    if let Some(path) = parse_lit_into_expr_path(cx, SKIP_SERIALIZING_IF, &meta)? {
-                        skip_serializing_if.set(&meta.path, path);
-                    }
-                } else if meta.path == SERIALIZE_WITH {
-                    // #[serde(serialize_with = "...")]
-                    if let Some(path) = parse_lit_into_expr_path(cx, SERIALIZE_WITH, &meta)? {
-                        serialize_with.set(&meta.path, path);
-                    }
-                } else if meta.path == DESERIALIZE_WITH {
-                    // #[serde(deserialize_with = "...")]
-                    if let Some(path) = parse_lit_into_expr_path(cx, DESERIALIZE_WITH, &meta)? {
-                        deserialize_with.set(&meta.path, path);
-                    }
-                } else if meta.path == WITH {
-                    // #[serde(with = "...")]
-                    if let Some(path) = parse_lit_into_expr_path(cx, WITH, &meta)? {
-                        let mut ser_path = path.clone();
-                        ser_path
-                            .path
-                            .segments
-                            .push(Ident::new("serialize", Span::call_site()).into());
-                        serialize_with.set(&meta.path, ser_path);
-                        let mut de_path = path;
-                        de_path
-                            .path
-                            .segments
-                            .push(Ident::new("deserialize", Span::call_site()).into());
-                        deserialize_with.set(&meta.path, de_path);
-                    }
-                } else if meta.path == BOUND {
-                    // #[serde(bound = "T: SomeBound")]
-                    // #[serde(bound(serialize = "...", deserialize = "..."))]
-                    let (ser, de) = get_where_predicates(cx, &meta)?;
-                    ser_bound.set_opt(&meta.path, ser);
-                    de_bound.set_opt(&meta.path, de);
-                } else if meta.path == BORROW {
-                    if meta.input.peek(Token![=]) {
-                        // #[serde(borrow = "'a + 'b")]
-                        let lifetimes = parse_lit_into_lifetimes(cx, &meta)?;
-                        if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, field) {
-                            for lifetime in &lifetimes {
-                                if !borrowable.contains(lifetime) {
-                                    let msg = format!(
-                                        "field `{}` does not have lifetime {}",
-                                        ident, lifetime,
-                                    );
-                                    cx.error_spanned_by(field, msg);
-                                }
-                            }
-                            borrowed_lifetimes.set(&meta.path, lifetimes);
-                        }
-                    } else {
-                        // #[serde(borrow)]
-                        if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, field) {
-                            borrowed_lifetimes.set(&meta.path, borrowable);
-                        }
-                    }
-                } else if meta.path == GETTER {
-                    // #[serde(getter = "...")]
-                    if let Some(path) = parse_lit_into_expr_path(cx, GETTER, &meta)? {
-                        getter.set(&meta.path, path);
-                    }
-                } else if meta.path == FLATTEN {
-                    // #[serde(flatten)]
-                    flatten.set_true(&meta.path);
-                } else {
-                    let path = meta.path.to_token_stream().to_string().replace(' ', "");
-                    return Err(
-                        meta.error(format_args!("unknown serde field attribute `{}`", path))
-                    );
-                }
-                Ok(())
-            }) {
-                cx.syn_error(err);
-            }
-        }
-
-        // Is skip_deserializing, initialize the field to Default::default() unless a
-        // different default is specified by `#[serde(default = "...")]` on
-        // ourselves or our container (e.g. the struct we are in).
-        if let Default::None = *container_default {
-            if skip_deserializing.0.value.is_some() {
-                default.set_if_none(Default::Default);
-            }
-        }
-
-        let mut borrowed_lifetimes = borrowed_lifetimes.get().unwrap_or_default();
-        if !borrowed_lifetimes.is_empty() {
-            // Cow<str> and Cow<[u8]> never borrow by default:
-            //
-            //     impl<'de, 'a, T: ?Sized> Deserialize<'de> for Cow<'a, T>
-            //
-            // A #[serde(borrow)] attribute enables borrowing that corresponds
-            // roughly to these impls:
-            //
-            //     impl<'de: 'a, 'a> Deserialize<'de> for Cow<'a, str>
-            //     impl<'de: 'a, 'a> Deserialize<'de> for Cow<'a, [u8]>
-            if is_cow(&field.ty, is_str) {
-                let mut path = syn::Path {
-                    leading_colon: None,
-                    segments: Punctuated::new(),
-                };
-                let span = Span::call_site();
-                path.segments.push(Ident::new("_serde", span).into());
-                path.segments.push(Ident::new("__private", span).into());
-                path.segments.push(Ident::new("de", span).into());
-                path.segments
-                    .push(Ident::new("borrow_cow_str", span).into());
-                let expr = syn::ExprPath {
-                    attrs: Vec::new(),
-                    qself: None,
-                    path,
-                };
-                deserialize_with.set_if_none(expr);
-            } else if is_cow(&field.ty, is_slice_u8) {
-                let mut path = syn::Path {
-                    leading_colon: None,
-                    segments: Punctuated::new(),
-                };
-                let span = Span::call_site();
-                path.segments.push(Ident::new("_serde", span).into());
-                path.segments.push(Ident::new("__private", span).into());
-                path.segments.push(Ident::new("de", span).into());
-                path.segments
-                    .push(Ident::new("borrow_cow_bytes", span).into());
-                let expr = syn::ExprPath {
-                    attrs: Vec::new(),
-                    qself: None,
-                    path,
-                };
-                deserialize_with.set_if_none(expr);
-            }
-        } else if is_implicitly_borrowed(&field.ty) {
-            // Types &str and &[u8] are always implicitly borrowed. No need for
-            // a #[serde(borrow)].
-            collect_lifetimes(&field.ty, &mut borrowed_lifetimes);
-        }
-
-        Field {
-            name: Name::from_attrs(ident, ser_name, de_name, Some(de_aliases)),
-            skip_serializing: skip_serializing.get(),
-            skip_deserializing: skip_deserializing.get(),
-            skip_serializing_if: skip_serializing_if.get(),
-            default: default.get().unwrap_or(Default::None),
-            serialize_with: serialize_with.get(),
-            deserialize_with: deserialize_with.get(),
-            ser_bound: ser_bound.get(),
-            de_bound: de_bound.get(),
-            borrowed_lifetimes,
-            getter: getter.get(),
-            flatten: flatten.get(),
-            transparent: false,
-        }
-    }
-
-    pub fn name(&self) -> &Name {
-        &self.name
-    }
-
-    pub fn aliases(&self) -> &BTreeSet<String> {
-        self.name.deserialize_aliases()
-    }
-
-    pub fn rename_by_rules(&mut self, rules: RenameAllRules) {
-        if !self.name.serialize_renamed {
-            self.name.serialize = rules.serialize.apply_to_field(&self.name.serialize);
-        }
-        if !self.name.deserialize_renamed {
-            self.name.deserialize = rules.deserialize.apply_to_field(&self.name.deserialize);
-        }
-        self.name
-            .deserialize_aliases
-            .insert(self.name.deserialize.clone());
-    }
-
-    pub fn skip_serializing(&self) -> bool {
-        self.skip_serializing
-    }
-
-    pub fn skip_deserializing(&self) -> bool {
-        self.skip_deserializing
-    }
-
-    pub fn skip_serializing_if(&self) -> Option<&syn::ExprPath> {
-        self.skip_serializing_if.as_ref()
-    }
-
-    pub fn default(&self) -> &Default {
-        &self.default
-    }
-
-    pub fn serialize_with(&self) -> Option<&syn::ExprPath> {
-        self.serialize_with.as_ref()
-    }
-
-    pub fn deserialize_with(&self) -> Option<&syn::ExprPath> {
-        self.deserialize_with.as_ref()
-    }
-
-    pub fn ser_bound(&self) -> Option<&[syn::WherePredicate]> {
-        self.ser_bound.as_ref().map(|vec| &vec[..])
-    }
-
-    pub fn de_bound(&self) -> Option<&[syn::WherePredicate]> {
-        self.de_bound.as_ref().map(|vec| &vec[..])
-    }
-
-    pub fn borrowed_lifetimes(&self) -> &BTreeSet<syn::Lifetime> {
-        &self.borrowed_lifetimes
-    }
-
-    pub fn getter(&self) -> Option<&syn::ExprPath> {
-        self.getter.as_ref()
-    }
-
-    pub fn flatten(&self) -> bool {
-        self.flatten
-    }
-
-    pub fn transparent(&self) -> bool {
-        self.transparent
-    }
-
-    pub fn mark_transparent(&mut self) {
-        self.transparent = true;
-    }
-}
-
-type SerAndDe<T> = (Option<T>, Option<T>);
-
-fn get_ser_and_de<'c, T, F, R>(
-    cx: &'c Ctxt,
-    attr_name: Symbol,
-    meta: &ParseNestedMeta,
-    f: F,
-) -> syn::Result<(VecAttr<'c, T>, VecAttr<'c, T>)>
-where
-    T: Clone,
-    F: Fn(&Ctxt, Symbol, Symbol, &ParseNestedMeta) -> syn::Result<R>,
-    R: Into<Option<T>>,
-{
-    let mut ser_meta = VecAttr::none(cx, attr_name);
-    let mut de_meta = VecAttr::none(cx, attr_name);
-
-    let lookahead = meta.input.lookahead1();
-    if lookahead.peek(Token![=]) {
-        if let Some(both) = f(cx, attr_name, attr_name, meta)?.into() {
-            ser_meta.insert(&meta.path, both.clone());
-            de_meta.insert(&meta.path, both);
-        }
-    } else if lookahead.peek(token::Paren) {
-        meta.parse_nested_meta(|meta| {
-            if meta.path == SERIALIZE {
-                if let Some(v) = f(cx, attr_name, SERIALIZE, &meta)?.into() {
-                    ser_meta.insert(&meta.path, v);
-                }
-            } else if meta.path == DESERIALIZE {
-                if let Some(v) = f(cx, attr_name, DESERIALIZE, &meta)?.into() {
-                    de_meta.insert(&meta.path, v);
-                }
-            } else {
-                return Err(meta.error(format_args!(
-                    "malformed {0} attribute, expected `{0}(serialize = ..., deserialize = ...)`",
-                    attr_name,
-                )));
-            }
-            Ok(())
-        })?;
-    } else {
-        return Err(lookahead.error());
-    }
-
-    Ok((ser_meta, de_meta))
-}
-
-fn get_renames(
-    cx: &Ctxt,
-    attr_name: Symbol,
-    meta: &ParseNestedMeta,
-) -> syn::Result<SerAndDe<syn::LitStr>> {
-    let (ser, de) = get_ser_and_de(cx, attr_name, meta, get_lit_str2)?;
-    Ok((ser.at_most_one(), de.at_most_one()))
-}
-
-fn get_multiple_renames(
-    cx: &Ctxt,
-    meta: &ParseNestedMeta,
-) -> syn::Result<(Option<syn::LitStr>, Vec<syn::LitStr>)> {
-    let (ser, de) = get_ser_and_de(cx, RENAME, meta, get_lit_str2)?;
-    Ok((ser.at_most_one(), de.get()))
-}
-
-fn get_where_predicates(
-    cx: &Ctxt,
-    meta: &ParseNestedMeta,
-) -> syn::Result<SerAndDe<Vec<syn::WherePredicate>>> {
-    let (ser, de) = get_ser_and_de(cx, BOUND, meta, parse_lit_into_where)?;
-    Ok((ser.at_most_one(), de.at_most_one()))
-}
-
-fn get_lit_str(
-    cx: &Ctxt,
-    attr_name: Symbol,
-    meta: &ParseNestedMeta,
-) -> syn::Result<Option<syn::LitStr>> {
-    get_lit_str2(cx, attr_name, attr_name, meta)
-}
-
-fn get_lit_str2(
-    cx: &Ctxt,
-    attr_name: Symbol,
-    meta_item_name: Symbol,
-    meta: &ParseNestedMeta,
-) -> syn::Result<Option<syn::LitStr>> {
-    let expr: syn::Expr = meta.value()?.parse()?;
-    let mut value = &expr;
-    while let syn::Expr::Group(e) = value {
-        value = &e.expr;
-    }
-    if let syn::Expr::Lit(syn::ExprLit {
-        lit: syn::Lit::Str(lit),
-        ..
-    }) = value
-    {
-        let suffix = lit.suffix();
-        if !suffix.is_empty() {
-            cx.error_spanned_by(
-                lit,
-                format!("unexpected suffix `{}` on string literal", suffix),
-            );
-        }
-        Ok(Some(lit.clone()))
-    } else {
-        cx.error_spanned_by(
-            expr,
-            format!(
-                "expected serde {} attribute to be a string: `{} = \"...\"`",
-                attr_name, meta_item_name
-            ),
-        );
-        Ok(None)
-    }
-}
-
-fn parse_lit_into_path(
-    cx: &Ctxt,
-    attr_name: Symbol,
-    meta: &ParseNestedMeta,
-) -> syn::Result<Option<syn::Path>> {
-    let string = match get_lit_str(cx, attr_name, meta)? {
-        Some(string) => string,
-        None => return Ok(None),
-    };
-
-    Ok(match string.parse() {
-        Ok(path) => Some(path),
-        Err(_) => {
-            cx.error_spanned_by(
-                &string,
-                format!("failed to parse path: {:?}", string.value()),
-            );
-            None
-        }
-    })
-}
-
-fn parse_lit_into_expr_path(
-    cx: &Ctxt,
-    attr_name: Symbol,
-    meta: &ParseNestedMeta,
-) -> syn::Result<Option<syn::ExprPath>> {
-    let string = match get_lit_str(cx, attr_name, meta)? {
-        Some(string) => string,
-        None => return Ok(None),
-    };
-
-    Ok(match string.parse() {
-        Ok(expr) => Some(expr),
-        Err(_) => {
-            cx.error_spanned_by(
-                &string,
-                format!("failed to parse path: {:?}", string.value()),
-            );
-            None
-        }
-    })
-}
-
-fn parse_lit_into_where(
-    cx: &Ctxt,
-    attr_name: Symbol,
-    meta_item_name: Symbol,
-    meta: &ParseNestedMeta,
-) -> syn::Result<Vec<syn::WherePredicate>> {
-    let string = match get_lit_str2(cx, attr_name, meta_item_name, meta)? {
-        Some(string) => string,
-        None => return Ok(Vec::new()),
-    };
-
-    Ok(
-        match string.parse_with(Punctuated::<syn::WherePredicate, Token![,]>::parse_terminated) {
-            Ok(predicates) => Vec::from_iter(predicates),
-            Err(err) => {
-                cx.error_spanned_by(string, err);
-                Vec::new()
-            }
-        },
-    )
-}
-
-fn parse_lit_into_ty(
-    cx: &Ctxt,
-    attr_name: Symbol,
-    meta: &ParseNestedMeta,
-) -> syn::Result<Option<syn::Type>> {
-    let string = match get_lit_str(cx, attr_name, meta)? {
-        Some(string) => string,
-        None => return Ok(None),
-    };
-
-    Ok(match string.parse() {
-        Ok(ty) => Some(ty),
-        Err(_) => {
-            cx.error_spanned_by(
-                &string,
-                format!("failed to parse type: {} = {:?}", attr_name, string.value()),
-            );
-            None
-        }
-    })
-}
-
-// Parses a string literal like "'a + 'b + 'c" containing a nonempty list of
-// lifetimes separated by `+`.
-fn parse_lit_into_lifetimes(
-    cx: &Ctxt,
-    meta: &ParseNestedMeta,
-) -> syn::Result<BTreeSet<syn::Lifetime>> {
-    let string = match get_lit_str(cx, BORROW, meta)? {
-        Some(string) => string,
-        None => return Ok(BTreeSet::new()),
-    };
-
-    if let Ok(lifetimes) = string.parse_with(|input: ParseStream| {
-        let mut set = BTreeSet::new();
-        while !input.is_empty() {
-            let lifetime: Lifetime = input.parse()?;
-            if !set.insert(lifetime.clone()) {
-                cx.error_spanned_by(
-                    &string,
-                    format!("duplicate borrowed lifetime `{}`", lifetime),
-                );
-            }
-            if input.is_empty() {
-                break;
-            }
-            input.parse::<Token![+]>()?;
-        }
-        Ok(set)
-    }) {
-        if lifetimes.is_empty() {
-            cx.error_spanned_by(string, "at least one lifetime must be borrowed");
-        }
-        return Ok(lifetimes);
-    }
-
-    cx.error_spanned_by(
-        &string,
-        format!("failed to parse borrowed lifetimes: {:?}", string.value()),
-    );
-    Ok(BTreeSet::new())
-}
-
-fn is_implicitly_borrowed(ty: &syn::Type) -> bool {
-    is_implicitly_borrowed_reference(ty) || is_option(ty, is_implicitly_borrowed_reference)
-}
-
-fn is_implicitly_borrowed_reference(ty: &syn::Type) -> bool {
-    is_reference(ty, is_str) || is_reference(ty, is_slice_u8)
-}
-
-// Whether the type looks like it might be `std::borrow::Cow<T>` where elem="T".
-// This can have false negatives and false positives.
-//
-// False negative:
-//
-//     use std::borrow::Cow as Pig;
-//
-//     #[derive(Deserialize)]
-//     struct S<'a> {
-//         #[serde(borrow)]
-//         pig: Pig<'a, str>,
-//     }
-//
-// False positive:
-//
-//     type str = [i16];
-//
-//     #[derive(Deserialize)]
-//     struct S<'a> {
-//         #[serde(borrow)]
-//         cow: Cow<'a, str>,
-//     }
-fn is_cow(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
-    let path = match ungroup(ty) {
-        syn::Type::Path(ty) => &ty.path,
-        _ => {
-            return false;
-        }
-    };
-    let seg = match path.segments.last() {
-        Some(seg) => seg,
-        None => {
-            return false;
-        }
-    };
-    let args = match &seg.arguments {
-        syn::PathArguments::AngleBracketed(bracketed) => &bracketed.args,
-        _ => {
-            return false;
-        }
-    };
-    seg.ident == "Cow"
-        && args.len() == 2
-        && match (&args[0], &args[1]) {
-            (syn::GenericArgument::Lifetime(_), syn::GenericArgument::Type(arg)) => elem(arg),
-            _ => false,
-        }
-}
-
-fn is_option(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
-    let path = match ungroup(ty) {
-        syn::Type::Path(ty) => &ty.path,
-        _ => {
-            return false;
-        }
-    };
-    let seg = match path.segments.last() {
-        Some(seg) => seg,
-        None => {
-            return false;
-        }
-    };
-    let args = match &seg.arguments {
-        syn::PathArguments::AngleBracketed(bracketed) => &bracketed.args,
-        _ => {
-            return false;
-        }
-    };
-    seg.ident == "Option"
-        && args.len() == 1
-        && match &args[0] {
-            syn::GenericArgument::Type(arg) => elem(arg),
-            _ => false,
-        }
-}
-
-// Whether the type looks like it might be `&T` where elem="T". This can have
-// false negatives and false positives.
-//
-// False negative:
-//
-//     type Yarn = str;
-//
-//     #[derive(Deserialize)]
-//     struct S<'a> {
-//         r: &'a Yarn,
-//     }
-//
-// False positive:
-//
-//     type str = [i16];
-//
-//     #[derive(Deserialize)]
-//     struct S<'a> {
-//         r: &'a str,
-//     }
-fn is_reference(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
-    match ungroup(ty) {
-        syn::Type::Reference(ty) => ty.mutability.is_none() && elem(&ty.elem),
-        _ => false,
-    }
-}
-
-fn is_str(ty: &syn::Type) -> bool {
-    is_primitive_type(ty, "str")
-}
-
-fn is_slice_u8(ty: &syn::Type) -> bool {
-    match ungroup(ty) {
-        syn::Type::Slice(ty) => is_primitive_type(&ty.elem, "u8"),
-        _ => false,
-    }
-}
-
-fn is_primitive_type(ty: &syn::Type, primitive: &str) -> bool {
-    match ungroup(ty) {
-        syn::Type::Path(ty) => ty.qself.is_none() && is_primitive_path(&ty.path, primitive),
-        _ => false,
-    }
-}
-
-fn is_primitive_path(path: &syn::Path, primitive: &str) -> bool {
-    path.leading_colon.is_none()
-        && path.segments.len() == 1
-        && path.segments[0].ident == primitive
-        && path.segments[0].arguments.is_empty()
-}
-
-// All lifetimes that this type could borrow from a Deserializer.
-//
-// For example a type `S<'a, 'b>` could borrow `'a` and `'b`. On the other hand
-// a type `for<'a> fn(&'a str)` could not borrow `'a` from the Deserializer.
-//
-// This is used when there is an explicit or implicit `#[serde(borrow)]`
-// attribute on the field so there must be at least one borrowable lifetime.
-fn borrowable_lifetimes(
-    cx: &Ctxt,
-    name: &str,
-    field: &syn::Field,
-) -> Result<BTreeSet<syn::Lifetime>, ()> {
-    let mut lifetimes = BTreeSet::new();
-    collect_lifetimes(&field.ty, &mut lifetimes);
-    if lifetimes.is_empty() {
-        let msg = format!("field `{}` has no lifetimes to borrow", name);
-        cx.error_spanned_by(field, msg);
-        Err(())
-    } else {
-        Ok(lifetimes)
-    }
-}
-
-fn collect_lifetimes(ty: &syn::Type, out: &mut BTreeSet<syn::Lifetime>) {
-    match ty {
-        #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
-        syn::Type::Slice(ty) => {
-            collect_lifetimes(&ty.elem, out);
-        }
-        syn::Type::Array(ty) => {
-            collect_lifetimes(&ty.elem, out);
-        }
-        syn::Type::Ptr(ty) => {
-            collect_lifetimes(&ty.elem, out);
-        }
-        syn::Type::Reference(ty) => {
-            out.extend(ty.lifetime.iter().cloned());
-            collect_lifetimes(&ty.elem, out);
-        }
-        syn::Type::Tuple(ty) => {
-            for elem in &ty.elems {
-                collect_lifetimes(elem, out);
-            }
-        }
-        syn::Type::Path(ty) => {
-            if let Some(qself) = &ty.qself {
-                collect_lifetimes(&qself.ty, out);
-            }
-            for seg in &ty.path.segments {
-                if let syn::PathArguments::AngleBracketed(bracketed) = &seg.arguments {
-                    for arg in &bracketed.args {
-                        match arg {
-                            syn::GenericArgument::Lifetime(lifetime) => {
-                                out.insert(lifetime.clone());
-                            }
-                            syn::GenericArgument::Type(ty) => {
-                                collect_lifetimes(ty, out);
-                            }
-                            syn::GenericArgument::AssocType(binding) => {
-                                collect_lifetimes(&binding.ty, out);
-                            }
-                            syn::GenericArgument::Const(_)
-                            | syn::GenericArgument::AssocConst(_)
-                            | syn::GenericArgument::Constraint(_)
-                            | _ => {}
-                        }
-                    }
-                }
-            }
-        }
-        syn::Type::Paren(ty) => {
-            collect_lifetimes(&ty.elem, out);
-        }
-        syn::Type::Group(ty) => {
-            collect_lifetimes(&ty.elem, out);
-        }
-        syn::Type::Macro(ty) => {
-            collect_lifetimes_from_tokens(ty.mac.tokens.clone(), out);
-        }
-        syn::Type::BareFn(_)
-        | syn::Type::Never(_)
-        | syn::Type::TraitObject(_)
-        | syn::Type::ImplTrait(_)
-        | syn::Type::Infer(_)
-        | syn::Type::Verbatim(_) => {}
-
-        _ => {}
-    }
-}
-
-fn collect_lifetimes_from_tokens(tokens: TokenStream, out: &mut BTreeSet<syn::Lifetime>) {
-    let mut iter = tokens.into_iter();
-    while let Some(tt) = iter.next() {
-        match &tt {
-            TokenTree::Punct(op) if op.as_char() == '\'' && op.spacing() == Spacing::Joint => {
-                if let Some(TokenTree::Ident(ident)) = iter.next() {
-                    out.insert(syn::Lifetime {
-                        apostrophe: op.span(),
-                        ident,
-                    });
-                }
-            }
-            TokenTree::Group(group) => {
-                let tokens = group.stream();
-                collect_lifetimes_from_tokens(tokens, out);
-            }
-            _ => {}
-        }
-    }
-}