Merging upstream version 1.71.1+dfsg1.

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

1 files changed, 3313 insertions, 0 deletions

diff --git a/vendor/syn-1.0.109/src/item.rs b/vendor/syn-1.0.109/src/item.rs
new file mode 100644
index 000000000..a1ef7ab43
--- /dev/null
+++ b/vendor/syn-1.0.109/src/item.rs
@@ -0,0 +1,3313 @@
+use super::*;
+use crate::derive::{Data, DataEnum, DataStruct, DataUnion, DeriveInput};
+use crate::punctuated::Punctuated;
+use proc_macro2::TokenStream;
+
+#[cfg(feature = "parsing")]
+use std::mem;
+
+ast_enum_of_structs! {
+    /// Things that can appear directly inside of a module or scope.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    #[cfg_attr(not(syn_no_non_exhaustive), non_exhaustive)]
+    pub enum Item {
+        /// A constant item: `const MAX: u16 = 65535`.
+        Const(ItemConst),
+
+        /// An enum definition: `enum Foo<A, B> { A(A), B(B) }`.
+        Enum(ItemEnum),
+
+        /// An `extern crate` item: `extern crate serde`.
+        ExternCrate(ItemExternCrate),
+
+        /// A free-standing function: `fn process(n: usize) -> Result<()> { ...
+        /// }`.
+        Fn(ItemFn),
+
+        /// A block of foreign items: `extern "C" { ... }`.
+        ForeignMod(ItemForeignMod),
+
+        /// An impl block providing trait or associated items: `impl<A> Trait
+        /// for Data<A> { ... }`.
+        Impl(ItemImpl),
+
+        /// A macro invocation, which includes `macro_rules!` definitions.
+        Macro(ItemMacro),
+
+        /// A 2.0-style declarative macro introduced by the `macro` keyword.
+        Macro2(ItemMacro2),
+
+        /// A module or module declaration: `mod m` or `mod m { ... }`.
+        Mod(ItemMod),
+
+        /// A static item: `static BIKE: Shed = Shed(42)`.
+        Static(ItemStatic),
+
+        /// A struct definition: `struct Foo<A> { x: A }`.
+        Struct(ItemStruct),
+
+        /// A trait definition: `pub trait Iterator { ... }`.
+        Trait(ItemTrait),
+
+        /// A trait alias: `pub trait SharableIterator = Iterator + Sync`.
+        TraitAlias(ItemTraitAlias),
+
+        /// A type alias: `type Result<T> = std::result::Result<T, MyError>`.
+        Type(ItemType),
+
+        /// A union definition: `union Foo<A, B> { x: A, y: B }`.
+        Union(ItemUnion),
+
+        /// A use declaration: `use std::collections::HashMap`.
+        Use(ItemUse),
+
+        /// Tokens forming an item not interpreted by Syn.
+        Verbatim(TokenStream),
+
+        // Not public API.
+        //
+        // For testing exhaustiveness in downstream code, use the following idiom:
+        //
+        //     match item {
+        //         Item::Const(item) => {...}
+        //         Item::Enum(item) => {...}
+        //         ...
+        //         Item::Verbatim(item) => {...}
+        //
+        //         #[cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+        //         _ => { /* some sane fallback */ }
+        //     }
+        //
+        // This way we fail your tests but don't break your library when adding
+        // a variant. You will be notified by a test failure when a variant is
+        // added, so that you can add code to handle it, but your library will
+        // continue to compile and work for downstream users in the interim.
+        #[cfg(syn_no_non_exhaustive)]
+        #[doc(hidden)]
+        __NonExhaustive,
+    }
+}
+
+ast_struct! {
+    /// A constant item: `const MAX: u16 = 65535`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemConst {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub const_token: Token![const],
+        pub ident: Ident,
+        pub colon_token: Token![:],
+        pub ty: Box<Type>,
+        pub eq_token: Token![=],
+        pub expr: Box<Expr>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// An enum definition: `enum Foo<A, B> { A(A), B(B) }`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemEnum {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub enum_token: Token![enum],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub brace_token: token::Brace,
+        pub variants: Punctuated<Variant, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// An `extern crate` item: `extern crate serde`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemExternCrate {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub extern_token: Token![extern],
+        pub crate_token: Token![crate],
+        pub ident: Ident,
+        pub rename: Option<(Token![as], Ident)>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A free-standing function: `fn process(n: usize) -> Result<()> { ...
+    /// }`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemFn {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub sig: Signature,
+        pub block: Box<Block>,
+    }
+}
+
+ast_struct! {
+    /// A block of foreign items: `extern "C" { ... }`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemForeignMod {
+        pub attrs: Vec<Attribute>,
+        pub abi: Abi,
+        pub brace_token: token::Brace,
+        pub items: Vec<ForeignItem>,
+    }
+}
+
+ast_struct! {
+    /// An impl block providing trait or associated items: `impl<A> Trait
+    /// for Data<A> { ... }`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemImpl {
+        pub attrs: Vec<Attribute>,
+        pub defaultness: Option<Token![default]>,
+        pub unsafety: Option<Token![unsafe]>,
+        pub impl_token: Token![impl],
+        pub generics: Generics,
+        /// Trait this impl implements.
+        pub trait_: Option<(Option<Token![!]>, Path, Token![for])>,
+        /// The Self type of the impl.
+        pub self_ty: Box<Type>,
+        pub brace_token: token::Brace,
+        pub items: Vec<ImplItem>,
+    }
+}
+
+ast_struct! {
+    /// A macro invocation, which includes `macro_rules!` definitions.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemMacro {
+        pub attrs: Vec<Attribute>,
+        /// The `example` in `macro_rules! example { ... }`.
+        pub ident: Option<Ident>,
+        pub mac: Macro,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_struct! {
+    /// A 2.0-style declarative macro introduced by the `macro` keyword.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemMacro2 {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub macro_token: Token![macro],
+        pub ident: Ident,
+        pub rules: TokenStream,
+    }
+}
+
+ast_struct! {
+    /// A module or module declaration: `mod m` or `mod m { ... }`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemMod {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub mod_token: Token![mod],
+        pub ident: Ident,
+        pub content: Option<(token::Brace, Vec<Item>)>,
+        pub semi: Option<Token![;]>,
+    }
+}
+
+ast_struct! {
+    /// A static item: `static BIKE: Shed = Shed(42)`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemStatic {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub static_token: Token![static],
+        pub mutability: Option<Token![mut]>,
+        pub ident: Ident,
+        pub colon_token: Token![:],
+        pub ty: Box<Type>,
+        pub eq_token: Token![=],
+        pub expr: Box<Expr>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A struct definition: `struct Foo<A> { x: A }`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemStruct {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub struct_token: Token![struct],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub fields: Fields,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_struct! {
+    /// A trait definition: `pub trait Iterator { ... }`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemTrait {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub unsafety: Option<Token![unsafe]>,
+        pub auto_token: Option<Token![auto]>,
+        pub trait_token: Token![trait],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub colon_token: Option<Token![:]>,
+        pub supertraits: Punctuated<TypeParamBound, Token![+]>,
+        pub brace_token: token::Brace,
+        pub items: Vec<TraitItem>,
+    }
+}
+
+ast_struct! {
+    /// A trait alias: `pub trait SharableIterator = Iterator + Sync`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemTraitAlias {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub trait_token: Token![trait],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub eq_token: Token![=],
+        pub bounds: Punctuated<TypeParamBound, Token![+]>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A type alias: `type Result<T> = std::result::Result<T, MyError>`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemType {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub type_token: Token![type],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub eq_token: Token![=],
+        pub ty: Box<Type>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A union definition: `union Foo<A, B> { x: A, y: B }`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemUnion {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub union_token: Token![union],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub fields: FieldsNamed,
+    }
+}
+
+ast_struct! {
+    /// A use declaration: `use std::collections::HashMap`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemUse {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub use_token: Token![use],
+        pub leading_colon: Option<Token![::]>,
+        pub tree: UseTree,
+        pub semi_token: Token![;],
+    }
+}
+
+impl Item {
+    #[cfg(feature = "parsing")]
+    pub(crate) fn replace_attrs(&mut self, new: Vec<Attribute>) -> Vec<Attribute> {
+        match self {
+            Item::ExternCrate(ItemExternCrate { attrs, .. })
+            | Item::Use(ItemUse { attrs, .. })
+            | Item::Static(ItemStatic { attrs, .. })
+            | Item::Const(ItemConst { attrs, .. })
+            | Item::Fn(ItemFn { attrs, .. })
+            | Item::Mod(ItemMod { attrs, .. })
+            | Item::ForeignMod(ItemForeignMod { attrs, .. })
+            | Item::Type(ItemType { attrs, .. })
+            | Item::Struct(ItemStruct { attrs, .. })
+            | Item::Enum(ItemEnum { attrs, .. })
+            | Item::Union(ItemUnion { attrs, .. })
+            | Item::Trait(ItemTrait { attrs, .. })
+            | Item::TraitAlias(ItemTraitAlias { attrs, .. })
+            | Item::Impl(ItemImpl { attrs, .. })
+            | Item::Macro(ItemMacro { attrs, .. })
+            | Item::Macro2(ItemMacro2 { attrs, .. }) => mem::replace(attrs, new),
+            Item::Verbatim(_) => Vec::new(),
+
+            #[cfg(syn_no_non_exhaustive)]
+            _ => unreachable!(),
+        }
+    }
+}
+
+impl From<DeriveInput> for Item {
+    fn from(input: DeriveInput) -> Item {
+        match input.data {
+            Data::Struct(data) => Item::Struct(ItemStruct {
+                attrs: input.attrs,
+                vis: input.vis,
+                struct_token: data.struct_token,
+                ident: input.ident,
+                generics: input.generics,
+                fields: data.fields,
+                semi_token: data.semi_token,
+            }),
+            Data::Enum(data) => Item::Enum(ItemEnum {
+                attrs: input.attrs,
+                vis: input.vis,
+                enum_token: data.enum_token,
+                ident: input.ident,
+                generics: input.generics,
+                brace_token: data.brace_token,
+                variants: data.variants,
+            }),
+            Data::Union(data) => Item::Union(ItemUnion {
+                attrs: input.attrs,
+                vis: input.vis,
+                union_token: data.union_token,
+                ident: input.ident,
+                generics: input.generics,
+                fields: data.fields,
+            }),
+        }
+    }
+}
+
+impl From<ItemStruct> for DeriveInput {
+    fn from(input: ItemStruct) -> DeriveInput {
+        DeriveInput {
+            attrs: input.attrs,
+            vis: input.vis,
+            ident: input.ident,
+            generics: input.generics,
+            data: Data::Struct(DataStruct {
+                struct_token: input.struct_token,
+                fields: input.fields,
+                semi_token: input.semi_token,
+            }),
+        }
+    }
+}
+
+impl From<ItemEnum> for DeriveInput {
+    fn from(input: ItemEnum) -> DeriveInput {
+        DeriveInput {
+            attrs: input.attrs,
+            vis: input.vis,
+            ident: input.ident,
+            generics: input.generics,
+            data: Data::Enum(DataEnum {
+                enum_token: input.enum_token,
+                brace_token: input.brace_token,
+                variants: input.variants,
+            }),
+        }
+    }
+}
+
+impl From<ItemUnion> for DeriveInput {
+    fn from(input: ItemUnion) -> DeriveInput {
+        DeriveInput {
+            attrs: input.attrs,
+            vis: input.vis,
+            ident: input.ident,
+            generics: input.generics,
+            data: Data::Union(DataUnion {
+                union_token: input.union_token,
+                fields: input.fields,
+            }),
+        }
+    }
+}
+
+ast_enum_of_structs! {
+    /// A suffix of an import tree in a `use` item: `Type as Renamed` or `*`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub enum UseTree {
+        /// A path prefix of imports in a `use` item: `std::...`.
+        Path(UsePath),
+
+        /// An identifier imported by a `use` item: `HashMap`.
+        Name(UseName),
+
+        /// An renamed identifier imported by a `use` item: `HashMap as Map`.
+        Rename(UseRename),
+
+        /// A glob import in a `use` item: `*`.
+        Glob(UseGlob),
+
+        /// A braced group of imports in a `use` item: `{A, B, C}`.
+        Group(UseGroup),
+    }
+}
+
+ast_struct! {
+    /// A path prefix of imports in a `use` item: `std::...`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct UsePath {
+        pub ident: Ident,
+        pub colon2_token: Token![::],
+        pub tree: Box<UseTree>,
+    }
+}
+
+ast_struct! {
+    /// An identifier imported by a `use` item: `HashMap`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct UseName {
+        pub ident: Ident,
+    }
+}
+
+ast_struct! {
+    /// An renamed identifier imported by a `use` item: `HashMap as Map`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct UseRename {
+        pub ident: Ident,
+        pub as_token: Token![as],
+        pub rename: Ident,
+    }
+}
+
+ast_struct! {
+    /// A glob import in a `use` item: `*`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct UseGlob {
+        pub star_token: Token![*],
+    }
+}
+
+ast_struct! {
+    /// A braced group of imports in a `use` item: `{A, B, C}`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct UseGroup {
+        pub brace_token: token::Brace,
+        pub items: Punctuated<UseTree, Token![,]>,
+    }
+}
+
+ast_enum_of_structs! {
+    /// An item within an `extern` block.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    #[cfg_attr(not(syn_no_non_exhaustive), non_exhaustive)]
+    pub enum ForeignItem {
+        /// A foreign function in an `extern` block.
+        Fn(ForeignItemFn),
+
+        /// A foreign static item in an `extern` block: `static ext: u8`.
+        Static(ForeignItemStatic),
+
+        /// A foreign type in an `extern` block: `type void`.
+        Type(ForeignItemType),
+
+        /// A macro invocation within an extern block.
+        Macro(ForeignItemMacro),
+
+        /// Tokens in an `extern` block not interpreted by Syn.
+        Verbatim(TokenStream),
+
+        // Not public API.
+        //
+        // For testing exhaustiveness in downstream code, use the following idiom:
+        //
+        //     match item {
+        //         ForeignItem::Fn(item) => {...}
+        //         ForeignItem::Static(item) => {...}
+        //         ...
+        //         ForeignItem::Verbatim(item) => {...}
+        //
+        //         #[cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+        //         _ => { /* some sane fallback */ }
+        //     }
+        //
+        // This way we fail your tests but don't break your library when adding
+        // a variant. You will be notified by a test failure when a variant is
+        // added, so that you can add code to handle it, but your library will
+        // continue to compile and work for downstream users in the interim.
+        #[cfg(syn_no_non_exhaustive)]
+        #[doc(hidden)]
+        __NonExhaustive,
+    }
+}
+
+ast_struct! {
+    /// A foreign function in an `extern` block.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ForeignItemFn {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub sig: Signature,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A foreign static item in an `extern` block: `static ext: u8`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ForeignItemStatic {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub static_token: Token![static],
+        pub mutability: Option<Token![mut]>,
+        pub ident: Ident,
+        pub colon_token: Token![:],
+        pub ty: Box<Type>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A foreign type in an `extern` block: `type void`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ForeignItemType {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub type_token: Token![type],
+        pub ident: Ident,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A macro invocation within an extern block.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ForeignItemMacro {
+        pub attrs: Vec<Attribute>,
+        pub mac: Macro,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_enum_of_structs! {
+    /// An item declaration within the definition of a trait.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    #[cfg_attr(not(syn_no_non_exhaustive), non_exhaustive)]
+    pub enum TraitItem {
+        /// An associated constant within the definition of a trait.
+        Const(TraitItemConst),
+
+        /// A trait method within the definition of a trait.
+        Method(TraitItemMethod),
+
+        /// An associated type within the definition of a trait.
+        Type(TraitItemType),
+
+        /// A macro invocation within the definition of a trait.
+        Macro(TraitItemMacro),
+
+        /// Tokens within the definition of a trait not interpreted by Syn.
+        Verbatim(TokenStream),
+
+        // Not public API.
+        //
+        // For testing exhaustiveness in downstream code, use the following idiom:
+        //
+        //     match item {
+        //         TraitItem::Const(item) => {...}
+        //         TraitItem::Method(item) => {...}
+        //         ...
+        //         TraitItem::Verbatim(item) => {...}
+        //
+        //         #[cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+        //         _ => { /* some sane fallback */ }
+        //     }
+        //
+        // This way we fail your tests but don't break your library when adding
+        // a variant. You will be notified by a test failure when a variant is
+        // added, so that you can add code to handle it, but your library will
+        // continue to compile and work for downstream users in the interim.
+        #[cfg(syn_no_non_exhaustive)]
+        #[doc(hidden)]
+        __NonExhaustive,
+    }
+}
+
+ast_struct! {
+    /// An associated constant within the definition of a trait.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct TraitItemConst {
+        pub attrs: Vec<Attribute>,
+        pub const_token: Token![const],
+        pub ident: Ident,
+        pub colon_token: Token![:],
+        pub ty: Type,
+        pub default: Option<(Token![=], Expr)>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A trait method within the definition of a trait.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct TraitItemMethod {
+        pub attrs: Vec<Attribute>,
+        pub sig: Signature,
+        pub default: Option<Block>,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_struct! {
+    /// An associated type within the definition of a trait.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct TraitItemType {
+        pub attrs: Vec<Attribute>,
+        pub type_token: Token![type],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub colon_token: Option<Token![:]>,
+        pub bounds: Punctuated<TypeParamBound, Token![+]>,
+        pub default: Option<(Token![=], Type)>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A macro invocation within the definition of a trait.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct TraitItemMacro {
+        pub attrs: Vec<Attribute>,
+        pub mac: Macro,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_enum_of_structs! {
+    /// An item within an impl block.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    #[cfg_attr(not(syn_no_non_exhaustive), non_exhaustive)]
+    pub enum ImplItem {
+        /// An associated constant within an impl block.
+        Const(ImplItemConst),
+
+        /// A method within an impl block.
+        Method(ImplItemMethod),
+
+        /// An associated type within an impl block.
+        Type(ImplItemType),
+
+        /// A macro invocation within an impl block.
+        Macro(ImplItemMacro),
+
+        /// Tokens within an impl block not interpreted by Syn.
+        Verbatim(TokenStream),
+
+        // Not public API.
+        //
+        // For testing exhaustiveness in downstream code, use the following idiom:
+        //
+        //     match item {
+        //         ImplItem::Const(item) => {...}
+        //         ImplItem::Method(item) => {...}
+        //         ...
+        //         ImplItem::Verbatim(item) => {...}
+        //
+        //         #[cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+        //         _ => { /* some sane fallback */ }
+        //     }
+        //
+        // This way we fail your tests but don't break your library when adding
+        // a variant. You will be notified by a test failure when a variant is
+        // added, so that you can add code to handle it, but your library will
+        // continue to compile and work for downstream users in the interim.
+        #[cfg(syn_no_non_exhaustive)]
+        #[doc(hidden)]
+        __NonExhaustive,
+    }
+}
+
+ast_struct! {
+    /// An associated constant within an impl block.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ImplItemConst {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub defaultness: Option<Token![default]>,
+        pub const_token: Token![const],
+        pub ident: Ident,
+        pub colon_token: Token![:],
+        pub ty: Type,
+        pub eq_token: Token![=],
+        pub expr: Expr,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A method within an impl block.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ImplItemMethod {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub defaultness: Option<Token![default]>,
+        pub sig: Signature,
+        pub block: Block,
+    }
+}
+
+ast_struct! {
+    /// An associated type within an impl block.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ImplItemType {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub defaultness: Option<Token![default]>,
+        pub type_token: Token![type],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub eq_token: Token![=],
+        pub ty: Type,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A macro invocation within an impl block.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ImplItemMacro {
+        pub attrs: Vec<Attribute>,
+        pub mac: Macro,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_struct! {
+    /// A function signature in a trait or implementation: `unsafe fn
+    /// initialize(&self)`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct Signature {
+        pub constness: Option<Token![const]>,
+        pub asyncness: Option<Token![async]>,
+        pub unsafety: Option<Token![unsafe]>,
+        pub abi: Option<Abi>,
+        pub fn_token: Token![fn],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub paren_token: token::Paren,
+        pub inputs: Punctuated<FnArg, Token![,]>,
+        pub variadic: Option<Variadic>,
+        pub output: ReturnType,
+    }
+}
+
+impl Signature {
+    /// A method's `self` receiver, such as `&self` or `self: Box<Self>`.
+    pub fn receiver(&self) -> Option<&FnArg> {
+        let arg = self.inputs.first()?;
+        match arg {
+            FnArg::Receiver(_) => Some(arg),
+            FnArg::Typed(PatType { pat, .. }) => {
+                if let Pat::Ident(PatIdent { ident, .. }) = &**pat {
+                    if ident == "self" {
+                        return Some(arg);
+                    }
+                }
+                None
+            }
+        }
+    }
+}
+
+ast_enum_of_structs! {
+    /// An argument in a function signature: the `n: usize` in `fn f(n: usize)`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub enum FnArg {
+        /// The `self` argument of an associated method, whether taken by value
+        /// or by reference.
+        ///
+        /// Note that `self` receivers with a specified type, such as `self:
+        /// Box<Self>`, are parsed as a `FnArg::Typed`.
+        Receiver(Receiver),
+
+        /// A function argument accepted by pattern and type.
+        Typed(PatType),
+    }
+}
+
+ast_struct! {
+    /// The `self` argument of an associated method, whether taken by value
+    /// or by reference.
+    ///
+    /// Note that `self` receivers with a specified type, such as `self:
+    /// Box<Self>`, are parsed as a `FnArg::Typed`.
+    ///
+    /// *This type is available only if Syn is built with the `"full"` feature.*
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct Receiver {
+        pub attrs: Vec<Attribute>,
+        pub reference: Option<(Token![&], Option<Lifetime>)>,
+        pub mutability: Option<Token![mut]>,
+        pub self_token: Token![self],
+    }
+}
+
+impl Receiver {
+    pub fn lifetime(&self) -> Option<&Lifetime> {
+        self.reference.as_ref()?.1.as_ref()
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub mod parsing {
+    use super::*;
+    use crate::ext::IdentExt;
+    use crate::parse::discouraged::Speculative;
+    use crate::parse::{Parse, ParseBuffer, ParseStream, Result};
+    use crate::token::Brace;
+    use proc_macro2::{Delimiter, Group, Punct, Spacing, TokenTree};
+    use std::iter::{self, FromIterator};
+
+    crate::custom_keyword!(macro_rules);
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Item {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let ahead = input.fork();
+            let vis: Visibility = ahead.parse()?;
+
+            let lookahead = ahead.lookahead1();
+            let mut item = if lookahead.peek(Token![fn]) || peek_signature(&ahead) {
+                let vis: Visibility = input.parse()?;
+                let sig: Signature = input.parse()?;
+                if input.peek(Token![;]) {
+                    input.parse::<Token![;]>()?;
+                    Ok(Item::Verbatim(verbatim::between(begin, input)))
+                } else {
+                    parse_rest_of_fn(input, Vec::new(), vis, sig).map(Item::Fn)
+                }
+            } else if lookahead.peek(Token![extern]) {
+                ahead.parse::<Token![extern]>()?;
+                let lookahead = ahead.lookahead1();
+                if lookahead.peek(Token![crate]) {
+                    input.parse().map(Item::ExternCrate)
+                } else if lookahead.peek(token::Brace) {
+                    input.parse().map(Item::ForeignMod)
+                } else if lookahead.peek(LitStr) {
+                    ahead.parse::<LitStr>()?;
+                    let lookahead = ahead.lookahead1();
+                    if lookahead.peek(token::Brace) {
+                        input.parse().map(Item::ForeignMod)
+                    } else {
+                        Err(lookahead.error())
+                    }
+                } else {
+                    Err(lookahead.error())
+                }
+            } else if lookahead.peek(Token![use]) {
+                input.parse().map(Item::Use)
+            } else if lookahead.peek(Token![static]) {
+                let vis = input.parse()?;
+                let static_token = input.parse()?;
+                let mutability = input.parse()?;
+                let ident = input.parse()?;
+                if input.peek(Token![=]) {
+                    input.parse::<Token![=]>()?;
+                    input.parse::<Expr>()?;
+                    input.parse::<Token![;]>()?;
+                    Ok(Item::Verbatim(verbatim::between(begin, input)))
+                } else {
+                    let colon_token = input.parse()?;
+                    let ty = input.parse()?;
+                    if input.peek(Token![;]) {
+                        input.parse::<Token![;]>()?;
+                        Ok(Item::Verbatim(verbatim::between(begin, input)))
+                    } else {
+                        Ok(Item::Static(ItemStatic {
+                            attrs: Vec::new(),
+                            vis,
+                            static_token,
+                            mutability,
+                            ident,
+                            colon_token,
+                            ty,
+                            eq_token: input.parse()?,
+                            expr: input.parse()?,
+                            semi_token: input.parse()?,
+                        }))
+                    }
+                }
+            } else if lookahead.peek(Token![const]) {
+                ahead.parse::<Token![const]>()?;
+                let lookahead = ahead.lookahead1();
+                if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                    let vis = input.parse()?;
+                    let const_token = input.parse()?;
+                    let ident = {
+                        let lookahead = input.lookahead1();
+                        if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                            input.call(Ident::parse_any)?
+                        } else {
+                            return Err(lookahead.error());
+                        }
+                    };
+                    let colon_token = input.parse()?;
+                    let ty = input.parse()?;
+                    if input.peek(Token![;]) {
+                        input.parse::<Token![;]>()?;
+                        Ok(Item::Verbatim(verbatim::between(begin, input)))
+                    } else {
+                        Ok(Item::Const(ItemConst {
+                            attrs: Vec::new(),
+                            vis,
+                            const_token,
+                            ident,
+                            colon_token,
+                            ty,
+                            eq_token: input.parse()?,
+                            expr: input.parse()?,
+                            semi_token: input.parse()?,
+                        }))
+                    }
+                } else {
+                    Err(lookahead.error())
+                }
+            } else if lookahead.peek(Token![unsafe]) {
+                ahead.parse::<Token![unsafe]>()?;
+                let lookahead = ahead.lookahead1();
+                if lookahead.peek(Token![trait])
+                    || lookahead.peek(Token![auto]) && ahead.peek2(Token![trait])
+                {
+                    input.parse().map(Item::Trait)
+                } else if lookahead.peek(Token![impl]) {
+                    let allow_verbatim_impl = true;
+                    if let Some(item) = parse_impl(input, allow_verbatim_impl)? {
+                        Ok(Item::Impl(item))
+                    } else {
+                        Ok(Item::Verbatim(verbatim::between(begin, input)))
+                    }
+                } else if lookahead.peek(Token![extern]) {
+                    input.parse::<Visibility>()?;
+                    input.parse::<Token![unsafe]>()?;
+                    input.parse::<ItemForeignMod>()?;
+                    Ok(Item::Verbatim(verbatim::between(begin, input)))
+                } else if lookahead.peek(Token![mod]) {
+                    input.parse::<Visibility>()?;
+                    input.parse::<Token![unsafe]>()?;
+                    input.parse::<ItemMod>()?;
+                    Ok(Item::Verbatim(verbatim::between(begin, input)))
+                } else {
+                    Err(lookahead.error())
+                }
+            } else if lookahead.peek(Token![mod]) {
+                input.parse().map(Item::Mod)
+            } else if lookahead.peek(Token![type]) {
+                parse_item_type(begin, input)
+            } else if lookahead.peek(Token![struct]) {
+                input.parse().map(Item::Struct)
+            } else if lookahead.peek(Token![enum]) {
+                input.parse().map(Item::Enum)
+            } else if lookahead.peek(Token![union]) && ahead.peek2(Ident) {
+                input.parse().map(Item::Union)
+            } else if lookahead.peek(Token![trait]) {
+                input.call(parse_trait_or_trait_alias)
+            } else if lookahead.peek(Token![auto]) && ahead.peek2(Token![trait]) {
+                input.parse().map(Item::Trait)
+            } else if lookahead.peek(Token![impl])
+                || lookahead.peek(Token![default]) && !ahead.peek2(Token![!])
+            {
+                let allow_verbatim_impl = true;
+                if let Some(item) = parse_impl(input, allow_verbatim_impl)? {
+                    Ok(Item::Impl(item))
+                } else {
+                    Ok(Item::Verbatim(verbatim::between(begin, input)))
+                }
+            } else if lookahead.peek(Token![macro]) {
+                input.parse().map(Item::Macro2)
+            } else if vis.is_inherited()
+                && (lookahead.peek(Ident)
+                    || lookahead.peek(Token![self])
+                    || lookahead.peek(Token![super])
+                    || lookahead.peek(Token![crate])
+                    || lookahead.peek(Token![::]))
+            {
+                input.parse().map(Item::Macro)
+            } else if ahead.peek(macro_rules) {
+                input.advance_to(&ahead);
+                input.parse::<ItemMacro>()?;
+                Ok(Item::Verbatim(verbatim::between(begin, input)))
+            } else {
+                Err(lookahead.error())
+            }?;
+
+            attrs.extend(item.replace_attrs(Vec::new()));
+            item.replace_attrs(attrs);
+            Ok(item)
+        }
+    }
+
+    struct FlexibleItemType {
+        vis: Visibility,
+        defaultness: Option<Token![default]>,
+        type_token: Token![type],
+        ident: Ident,
+        generics: Generics,
+        colon_token: Option<Token![:]>,
+        bounds: Punctuated<TypeParamBound, Token![+]>,
+        ty: Option<(Token![=], Type)>,
+        semi_token: Token![;],
+    }
+
+    enum WhereClauseLocation {
+        // type Ty<T> where T: 'static = T;
+        BeforeEq,
+        // type Ty<T> = T where T: 'static;
+        #[allow(dead_code)]
+        AfterEq,
+        // TODO: goes away once the migration period on rust-lang/rust#89122 is over
+        Both,
+    }
+
+    impl FlexibleItemType {
+        fn parse(input: ParseStream, where_clause_location: WhereClauseLocation) -> Result<Self> {
+            let vis: Visibility = input.parse()?;
+            let defaultness: Option<Token![default]> = input.parse()?;
+            let type_token: Token![type] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let mut generics: Generics = input.parse()?;
+            let colon_token: Option<Token![:]> = input.parse()?;
+
+            let mut bounds = Punctuated::new();
+            if colon_token.is_some() {
+                loop {
+                    if input.peek(Token![where]) || input.peek(Token![=]) || input.peek(Token![;]) {
+                        break;
+                    }
+                    bounds.push_value(input.parse::<TypeParamBound>()?);
+                    if input.peek(Token![where]) || input.peek(Token![=]) || input.peek(Token![;]) {
+                        break;
+                    }
+                    bounds.push_punct(input.parse::<Token![+]>()?);
+                }
+            }
+
+            match where_clause_location {
+                WhereClauseLocation::BeforeEq | WhereClauseLocation::Both => {
+                    generics.where_clause = input.parse()?;
+                }
+                _ => {}
+            }
+
+            let ty = if let Some(eq_token) = input.parse()? {
+                Some((eq_token, input.parse::<Type>()?))
+            } else {
+                None
+            };
+
+            match where_clause_location {
+                WhereClauseLocation::AfterEq | WhereClauseLocation::Both
+                    if generics.where_clause.is_none() =>
+                {
+                    generics.where_clause = input.parse()?;
+                }
+                _ => {}
+            }
+
+            let semi_token: Token![;] = input.parse()?;
+
+            Ok(FlexibleItemType {
+                vis,
+                defaultness,
+                type_token,
+                ident,
+                generics,
+                colon_token,
+                bounds,
+                ty,
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemMacro {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let path = input.call(Path::parse_mod_style)?;
+            let bang_token: Token![!] = input.parse()?;
+            let ident: Option<Ident> = input.parse()?;
+            let (delimiter, tokens) = input.call(mac::parse_delimiter)?;
+            let semi_token: Option<Token![;]> = if !delimiter.is_brace() {
+                Some(input.parse()?)
+            } else {
+                None
+            };
+            Ok(ItemMacro {
+                attrs,
+                ident,
+                mac: Macro {
+                    path,
+                    bang_token,
+                    delimiter,
+                    tokens,
+                },
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemMacro2 {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let macro_token: Token![macro] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let mut rules = TokenStream::new();
+
+            let mut lookahead = input.lookahead1();
+            if lookahead.peek(token::Paren) {
+                let paren_content;
+                let paren_token = parenthesized!(paren_content in input);
+                let args: TokenStream = paren_content.parse()?;
+                let mut args = Group::new(Delimiter::Parenthesis, args);
+                args.set_span(paren_token.span);
+                rules.extend(iter::once(TokenTree::Group(args)));
+                lookahead = input.lookahead1();
+            }
+
+            if lookahead.peek(token::Brace) {
+                let brace_content;
+                let brace_token = braced!(brace_content in input);
+                let body: TokenStream = brace_content.parse()?;
+                let mut body = Group::new(Delimiter::Brace, body);
+                body.set_span(brace_token.span);
+                rules.extend(iter::once(TokenTree::Group(body)));
+            } else {
+                return Err(lookahead.error());
+            }
+
+            Ok(ItemMacro2 {
+                attrs,
+                vis,
+                macro_token,
+                ident,
+                rules,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemExternCrate {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ItemExternCrate {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                extern_token: input.parse()?,
+                crate_token: input.parse()?,
+                ident: {
+                    if input.peek(Token![self]) {
+                        input.call(Ident::parse_any)?
+                    } else {
+                        input.parse()?
+                    }
+                },
+                rename: {
+                    if input.peek(Token![as]) {
+                        let as_token: Token![as] = input.parse()?;
+                        let rename: Ident = if input.peek(Token![_]) {
+                            Ident::from(input.parse::<Token![_]>()?)
+                        } else {
+                            input.parse()?
+                        };
+                        Some((as_token, rename))
+                    } else {
+                        None
+                    }
+                },
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemUse {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ItemUse {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                use_token: input.parse()?,
+                leading_colon: input.parse()?,
+                tree: input.parse()?,
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for UseTree {
+        fn parse(input: ParseStream) -> Result<UseTree> {
+            let lookahead = input.lookahead1();
+            if lookahead.peek(Ident)
+                || lookahead.peek(Token![self])
+                || lookahead.peek(Token![super])
+                || lookahead.peek(Token![crate])
+            {
+                let ident = input.call(Ident::parse_any)?;
+                if input.peek(Token![::]) {
+                    Ok(UseTree::Path(UsePath {
+                        ident,
+                        colon2_token: input.parse()?,
+                        tree: Box::new(input.parse()?),
+                    }))
+                } else if input.peek(Token![as]) {
+                    Ok(UseTree::Rename(UseRename {
+                        ident,
+                        as_token: input.parse()?,
+                        rename: {
+                            if input.peek(Ident) {
+                                input.parse()?
+                            } else if input.peek(Token![_]) {
+                                Ident::from(input.parse::<Token![_]>()?)
+                            } else {
+                                return Err(input.error("expected identifier or underscore"));
+                            }
+                        },
+                    }))
+                } else {
+                    Ok(UseTree::Name(UseName { ident }))
+                }
+            } else if lookahead.peek(Token![*]) {
+                Ok(UseTree::Glob(UseGlob {
+                    star_token: input.parse()?,
+                }))
+            } else if lookahead.peek(token::Brace) {
+                let content;
+                Ok(UseTree::Group(UseGroup {
+                    brace_token: braced!(content in input),
+                    items: content.parse_terminated(UseTree::parse)?,
+                }))
+            } else {
+                Err(lookahead.error())
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemStatic {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ItemStatic {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                static_token: input.parse()?,
+                mutability: input.parse()?,
+                ident: input.parse()?,
+                colon_token: input.parse()?,
+                ty: input.parse()?,
+                eq_token: input.parse()?,
+                expr: input.parse()?,
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemConst {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ItemConst {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                const_token: input.parse()?,
+                ident: {
+                    let lookahead = input.lookahead1();
+                    if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                        input.call(Ident::parse_any)?
+                    } else {
+                        return Err(lookahead.error());
+                    }
+                },
+                colon_token: input.parse()?,
+                ty: input.parse()?,
+                eq_token: input.parse()?,
+                expr: input.parse()?,
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    fn pop_variadic(args: &mut Punctuated<FnArg, Token![,]>) -> Option<Variadic> {
+        let trailing_punct = args.trailing_punct();
+
+        let last = match args.last_mut()? {
+            FnArg::Typed(last) => last,
+            _ => return None,
+        };
+
+        let ty = match last.ty.as_ref() {
+            Type::Verbatim(ty) => ty,
+            _ => return None,
+        };
+
+        let mut variadic = Variadic {
+            attrs: Vec::new(),
+            dots: parse2(ty.clone()).ok()?,
+        };
+
+        if let Pat::Verbatim(pat) = last.pat.as_ref() {
+            if pat.to_string() == "..." && !trailing_punct {
+                variadic.attrs = mem::replace(&mut last.attrs, Vec::new());
+                args.pop();
+            }
+        }
+
+        Some(variadic)
+    }
+
+    fn variadic_to_tokens(dots: &Token![...]) -> TokenStream {
+        TokenStream::from_iter(vec![
+            TokenTree::Punct({
+                let mut dot = Punct::new('.', Spacing::Joint);
+                dot.set_span(dots.spans[0]);
+                dot
+            }),
+            TokenTree::Punct({
+                let mut dot = Punct::new('.', Spacing::Joint);
+                dot.set_span(dots.spans[1]);
+                dot
+            }),
+            TokenTree::Punct({
+                let mut dot = Punct::new('.', Spacing::Alone);
+                dot.set_span(dots.spans[2]);
+                dot
+            }),
+        ])
+    }
+
+    fn peek_signature(input: ParseStream) -> bool {
+        let fork = input.fork();
+        fork.parse::<Option<Token![const]>>().is_ok()
+            && fork.parse::<Option<Token![async]>>().is_ok()
+            && fork.parse::<Option<Token![unsafe]>>().is_ok()
+            && fork.parse::<Option<Abi>>().is_ok()
+            && fork.peek(Token![fn])
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Signature {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let constness: Option<Token![const]> = input.parse()?;
+            let asyncness: Option<Token![async]> = input.parse()?;
+            let unsafety: Option<Token![unsafe]> = input.parse()?;
+            let abi: Option<Abi> = input.parse()?;
+            let fn_token: Token![fn] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let mut generics: Generics = input.parse()?;
+
+            let content;
+            let paren_token = parenthesized!(content in input);
+            let mut inputs = parse_fn_args(&content)?;
+            let variadic = pop_variadic(&mut inputs);
+
+            let output: ReturnType = input.parse()?;
+            generics.where_clause = input.parse()?;
+
+            Ok(Signature {
+                constness,
+                asyncness,
+                unsafety,
+                abi,
+                fn_token,
+                ident,
+                generics,
+                paren_token,
+                inputs,
+                variadic,
+                output,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemFn {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let outer_attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let sig: Signature = input.parse()?;
+            parse_rest_of_fn(input, outer_attrs, vis, sig)
+        }
+    }
+
+    fn parse_rest_of_fn(
+        input: ParseStream,
+        mut attrs: Vec<Attribute>,
+        vis: Visibility,
+        sig: Signature,
+    ) -> Result<ItemFn> {
+        let content;
+        let brace_token = braced!(content in input);
+        attr::parsing::parse_inner(&content, &mut attrs)?;
+        let stmts = content.call(Block::parse_within)?;
+
+        Ok(ItemFn {
+            attrs,
+            vis,
+            sig,
+            block: Box::new(Block { brace_token, stmts }),
+        })
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for FnArg {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+
+            let ahead = input.fork();
+            if let Ok(mut receiver) = ahead.parse::<Receiver>() {
+                if !ahead.peek(Token![:]) {
+                    input.advance_to(&ahead);
+                    receiver.attrs = attrs;
+                    return Ok(FnArg::Receiver(receiver));
+                }
+            }
+
+            let mut typed = input.call(fn_arg_typed)?;
+            typed.attrs = attrs;
+            Ok(FnArg::Typed(typed))
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Receiver {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(Receiver {
+                attrs: Vec::new(),
+                reference: {
+                    if input.peek(Token![&]) {
+                        Some((input.parse()?, input.parse()?))
+                    } else {
+                        None
+                    }
+                },
+                mutability: input.parse()?,
+                self_token: input.parse()?,
+            })
+        }
+    }
+
+    fn parse_fn_args(input: ParseStream) -> Result<Punctuated<FnArg, Token![,]>> {
+        let mut args = Punctuated::new();
+        let mut has_receiver = false;
+
+        while !input.is_empty() {
+            let attrs = input.call(Attribute::parse_outer)?;
+
+            let arg = if let Some(dots) = input.parse::<Option<Token![...]>>()? {
+                FnArg::Typed(PatType {
+                    attrs,
+                    pat: Box::new(Pat::Verbatim(variadic_to_tokens(&dots))),
+                    colon_token: Token![:](dots.spans[0]),
+                    ty: Box::new(Type::Verbatim(variadic_to_tokens(&dots))),
+                })
+            } else {
+                let mut arg: FnArg = input.parse()?;
+                match &mut arg {
+                    FnArg::Receiver(receiver) if has_receiver => {
+                        return Err(Error::new(
+                            receiver.self_token.span,
+                            "unexpected second method receiver",
+                        ));
+                    }
+                    FnArg::Receiver(receiver) if !args.is_empty() => {
+                        return Err(Error::new(
+                            receiver.self_token.span,
+                            "unexpected method receiver",
+                        ));
+                    }
+                    FnArg::Receiver(receiver) => {
+                        has_receiver = true;
+                        receiver.attrs = attrs;
+                    }
+                    FnArg::Typed(arg) => arg.attrs = attrs,
+                }
+                arg
+            };
+            args.push_value(arg);
+
+            if input.is_empty() {
+                break;
+            }
+
+            let comma: Token![,] = input.parse()?;
+            args.push_punct(comma);
+        }
+
+        Ok(args)
+    }
+
+    fn fn_arg_typed(input: ParseStream) -> Result<PatType> {
+        // Hack to parse pre-2018 syntax in
+        // test/ui/rfc-2565-param-attrs/param-attrs-pretty.rs
+        // because the rest of the test case is valuable.
+        if input.peek(Ident) && input.peek2(Token![<]) {
+            let span = input.fork().parse::<Ident>()?.span();
+            return Ok(PatType {
+                attrs: Vec::new(),
+                pat: Box::new(Pat::Wild(PatWild {
+                    attrs: Vec::new(),
+                    underscore_token: Token![_](span),
+                })),
+                colon_token: Token![:](span),
+                ty: input.parse()?,
+            });
+        }
+
+        Ok(PatType {
+            attrs: Vec::new(),
+            pat: Box::new(pat::parsing::multi_pat(input)?),
+            colon_token: input.parse()?,
+            ty: Box::new(match input.parse::<Option<Token![...]>>()? {
+                Some(dot3) => Type::Verbatim(variadic_to_tokens(&dot3)),
+                None => input.parse()?,
+            }),
+        })
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemMod {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let mod_token: Token![mod] = input.parse()?;
+            let ident: Ident = input.parse()?;
+
+            let lookahead = input.lookahead1();
+            if lookahead.peek(Token![;]) {
+                Ok(ItemMod {
+                    attrs,
+                    vis,
+                    mod_token,
+                    ident,
+                    content: None,
+                    semi: Some(input.parse()?),
+                })
+            } else if lookahead.peek(token::Brace) {
+                let content;
+                let brace_token = braced!(content in input);
+                attr::parsing::parse_inner(&content, &mut attrs)?;
+
+                let mut items = Vec::new();
+                while !content.is_empty() {
+                    items.push(content.parse()?);
+                }
+
+                Ok(ItemMod {
+                    attrs,
+                    vis,
+                    mod_token,
+                    ident,
+                    content: Some((brace_token, items)),
+                    semi: None,
+                })
+            } else {
+                Err(lookahead.error())
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemForeignMod {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let abi: Abi = input.parse()?;
+
+            let content;
+            let brace_token = braced!(content in input);
+            attr::parsing::parse_inner(&content, &mut attrs)?;
+            let mut items = Vec::new();
+            while !content.is_empty() {
+                items.push(content.parse()?);
+            }
+
+            Ok(ItemForeignMod {
+                attrs,
+                abi,
+                brace_token,
+                items,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ForeignItem {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let ahead = input.fork();
+            let vis: Visibility = ahead.parse()?;
+
+            let lookahead = ahead.lookahead1();
+            let mut item = if lookahead.peek(Token![fn]) || peek_signature(&ahead) {
+                let vis: Visibility = input.parse()?;
+                let sig: Signature = input.parse()?;
+                if input.peek(token::Brace) {
+                    let content;
+                    braced!(content in input);
+                    content.call(Attribute::parse_inner)?;
+                    content.call(Block::parse_within)?;
+
+                    Ok(ForeignItem::Verbatim(verbatim::between(begin, input)))
+                } else {
+                    Ok(ForeignItem::Fn(ForeignItemFn {
+                        attrs: Vec::new(),
+                        vis,
+                        sig,
+                        semi_token: input.parse()?,
+                    }))
+                }
+            } else if lookahead.peek(Token![static]) {
+                let vis = input.parse()?;
+                let static_token = input.parse()?;
+                let mutability = input.parse()?;
+                let ident = input.parse()?;
+                let colon_token = input.parse()?;
+                let ty = input.parse()?;
+                if input.peek(Token![=]) {
+                    input.parse::<Token![=]>()?;
+                    input.parse::<Expr>()?;
+                    input.parse::<Token![;]>()?;
+                    Ok(ForeignItem::Verbatim(verbatim::between(begin, input)))
+                } else {
+                    Ok(ForeignItem::Static(ForeignItemStatic {
+                        attrs: Vec::new(),
+                        vis,
+                        static_token,
+                        mutability,
+                        ident,
+                        colon_token,
+                        ty,
+                        semi_token: input.parse()?,
+                    }))
+                }
+            } else if lookahead.peek(Token![type]) {
+                parse_foreign_item_type(begin, input)
+            } else if vis.is_inherited()
+                && (lookahead.peek(Ident)
+                    || lookahead.peek(Token![self])
+                    || lookahead.peek(Token![super])
+                    || lookahead.peek(Token![crate])
+                    || lookahead.peek(Token![::]))
+            {
+                input.parse().map(ForeignItem::Macro)
+            } else {
+                Err(lookahead.error())
+            }?;
+
+            let item_attrs = match &mut item {
+                ForeignItem::Fn(item) => &mut item.attrs,
+                ForeignItem::Static(item) => &mut item.attrs,
+                ForeignItem::Type(item) => &mut item.attrs,
+                ForeignItem::Macro(item) => &mut item.attrs,
+                ForeignItem::Verbatim(_) => return Ok(item),
+
+                #[cfg(syn_no_non_exhaustive)]
+                _ => unreachable!(),
+            };
+            attrs.append(item_attrs);
+            *item_attrs = attrs;
+
+            Ok(item)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ForeignItemFn {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let sig: Signature = input.parse()?;
+            let semi_token: Token![;] = input.parse()?;
+            Ok(ForeignItemFn {
+                attrs,
+                vis,
+                sig,
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ForeignItemStatic {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ForeignItemStatic {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                static_token: input.parse()?,
+                mutability: input.parse()?,
+                ident: input.parse()?,
+                colon_token: input.parse()?,
+                ty: input.parse()?,
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ForeignItemType {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ForeignItemType {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                type_token: input.parse()?,
+                ident: input.parse()?,
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    fn parse_foreign_item_type(begin: ParseBuffer, input: ParseStream) -> Result<ForeignItem> {
+        let FlexibleItemType {
+            vis,
+            defaultness,
+            type_token,
+            ident,
+            generics,
+            colon_token,
+            bounds: _,
+            ty,
+            semi_token,
+        } = FlexibleItemType::parse(input, WhereClauseLocation::BeforeEq)?;
+
+        if defaultness.is_some()
+            || generics.lt_token.is_some()
+            || generics.where_clause.is_some()
+            || colon_token.is_some()
+            || ty.is_some()
+        {
+            Ok(ForeignItem::Verbatim(verbatim::between(begin, input)))
+        } else {
+            Ok(ForeignItem::Type(ForeignItemType {
+                attrs: Vec::new(),
+                vis,
+                type_token,
+                ident,
+                semi_token,
+            }))
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ForeignItemMacro {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let mac: Macro = input.parse()?;
+            let semi_token: Option<Token![;]> = if mac.delimiter.is_brace() {
+                None
+            } else {
+                Some(input.parse()?)
+            };
+            Ok(ForeignItemMacro {
+                attrs,
+                mac,
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemType {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ItemType {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                type_token: input.parse()?,
+                ident: input.parse()?,
+                generics: {
+                    let mut generics: Generics = input.parse()?;
+                    generics.where_clause = input.parse()?;
+                    generics
+                },
+                eq_token: input.parse()?,
+                ty: input.parse()?,
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    fn parse_item_type(begin: ParseBuffer, input: ParseStream) -> Result<Item> {
+        let FlexibleItemType {
+            vis,
+            defaultness,
+            type_token,
+            ident,
+            generics,
+            colon_token,
+            bounds: _,
+            ty,
+            semi_token,
+        } = FlexibleItemType::parse(input, WhereClauseLocation::BeforeEq)?;
+
+        if defaultness.is_some() || colon_token.is_some() || ty.is_none() {
+            Ok(Item::Verbatim(verbatim::between(begin, input)))
+        } else {
+            let (eq_token, ty) = ty.unwrap();
+            Ok(Item::Type(ItemType {
+                attrs: Vec::new(),
+                vis,
+                type_token,
+                ident,
+                generics,
+                eq_token,
+                ty: Box::new(ty),
+                semi_token,
+            }))
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemStruct {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis = input.parse::<Visibility>()?;
+            let struct_token = input.parse::<Token![struct]>()?;
+            let ident = input.parse::<Ident>()?;
+            let generics = input.parse::<Generics>()?;
+            let (where_clause, fields, semi_token) = derive::parsing::data_struct(input)?;
+            Ok(ItemStruct {
+                attrs,
+                vis,
+                struct_token,
+                ident,
+                generics: Generics {
+                    where_clause,
+                    ..generics
+                },
+                fields,
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemEnum {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis = input.parse::<Visibility>()?;
+            let enum_token = input.parse::<Token![enum]>()?;
+            let ident = input.parse::<Ident>()?;
+            let generics = input.parse::<Generics>()?;
+            let (where_clause, brace_token, variants) = derive::parsing::data_enum(input)?;
+            Ok(ItemEnum {
+                attrs,
+                vis,
+                enum_token,
+                ident,
+                generics: Generics {
+                    where_clause,
+                    ..generics
+                },
+                brace_token,
+                variants,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemUnion {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis = input.parse::<Visibility>()?;
+            let union_token = input.parse::<Token![union]>()?;
+            let ident = input.parse::<Ident>()?;
+            let generics = input.parse::<Generics>()?;
+            let (where_clause, fields) = derive::parsing::data_union(input)?;
+            Ok(ItemUnion {
+                attrs,
+                vis,
+                union_token,
+                ident,
+                generics: Generics {
+                    where_clause,
+                    ..generics
+                },
+                fields,
+            })
+        }
+    }
+
+    fn parse_trait_or_trait_alias(input: ParseStream) -> Result<Item> {
+        let (attrs, vis, trait_token, ident, generics) = parse_start_of_trait_alias(input)?;
+        let lookahead = input.lookahead1();
+        if lookahead.peek(token::Brace)
+            || lookahead.peek(Token![:])
+            || lookahead.peek(Token![where])
+        {
+            let unsafety = None;
+            let auto_token = None;
+            parse_rest_of_trait(
+                input,
+                attrs,
+                vis,
+                unsafety,
+                auto_token,
+                trait_token,
+                ident,
+                generics,
+            )
+            .map(Item::Trait)
+        } else if lookahead.peek(Token![=]) {
+            parse_rest_of_trait_alias(input, attrs, vis, trait_token, ident, generics)
+                .map(Item::TraitAlias)
+        } else {
+            Err(lookahead.error())
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemTrait {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let outer_attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let unsafety: Option<Token![unsafe]> = input.parse()?;
+            let auto_token: Option<Token![auto]> = input.parse()?;
+            let trait_token: Token![trait] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let generics: Generics = input.parse()?;
+            parse_rest_of_trait(
+                input,
+                outer_attrs,
+                vis,
+                unsafety,
+                auto_token,
+                trait_token,
+                ident,
+                generics,
+            )
+        }
+    }
+
+    fn parse_rest_of_trait(
+        input: ParseStream,
+        mut attrs: Vec<Attribute>,
+        vis: Visibility,
+        unsafety: Option<Token![unsafe]>,
+        auto_token: Option<Token![auto]>,
+        trait_token: Token![trait],
+        ident: Ident,
+        mut generics: Generics,
+    ) -> Result<ItemTrait> {
+        let colon_token: Option<Token![:]> = input.parse()?;
+
+        let mut supertraits = Punctuated::new();
+        if colon_token.is_some() {
+            loop {
+                if input.peek(Token![where]) || input.peek(token::Brace) {
+                    break;
+                }
+                supertraits.push_value(input.parse()?);
+                if input.peek(Token![where]) || input.peek(token::Brace) {
+                    break;
+                }
+                supertraits.push_punct(input.parse()?);
+            }
+        }
+
+        generics.where_clause = input.parse()?;
+
+        let content;
+        let brace_token = braced!(content in input);
+        attr::parsing::parse_inner(&content, &mut attrs)?;
+        let mut items = Vec::new();
+        while !content.is_empty() {
+            items.push(content.parse()?);
+        }
+
+        Ok(ItemTrait {
+            attrs,
+            vis,
+            unsafety,
+            auto_token,
+            trait_token,
+            ident,
+            generics,
+            colon_token,
+            supertraits,
+            brace_token,
+            items,
+        })
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemTraitAlias {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let (attrs, vis, trait_token, ident, generics) = parse_start_of_trait_alias(input)?;
+            parse_rest_of_trait_alias(input, attrs, vis, trait_token, ident, generics)
+        }
+    }
+
+    fn parse_start_of_trait_alias(
+        input: ParseStream,
+    ) -> Result<(Vec<Attribute>, Visibility, Token![trait], Ident, Generics)> {
+        let attrs = input.call(Attribute::parse_outer)?;
+        let vis: Visibility = input.parse()?;
+        let trait_token: Token![trait] = input.parse()?;
+        let ident: Ident = input.parse()?;
+        let generics: Generics = input.parse()?;
+        Ok((attrs, vis, trait_token, ident, generics))
+    }
+
+    fn parse_rest_of_trait_alias(
+        input: ParseStream,
+        attrs: Vec<Attribute>,
+        vis: Visibility,
+        trait_token: Token![trait],
+        ident: Ident,
+        mut generics: Generics,
+    ) -> Result<ItemTraitAlias> {
+        let eq_token: Token![=] = input.parse()?;
+
+        let mut bounds = Punctuated::new();
+        loop {
+            if input.peek(Token![where]) || input.peek(Token![;]) {
+                break;
+            }
+            bounds.push_value(input.parse()?);
+            if input.peek(Token![where]) || input.peek(Token![;]) {
+                break;
+            }
+            bounds.push_punct(input.parse()?);
+        }
+
+        generics.where_clause = input.parse()?;
+        let semi_token: Token![;] = input.parse()?;
+
+        Ok(ItemTraitAlias {
+            attrs,
+            vis,
+            trait_token,
+            ident,
+            generics,
+            eq_token,
+            bounds,
+            semi_token,
+        })
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TraitItem {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let defaultness: Option<Token![default]> = input.parse()?;
+            let ahead = input.fork();
+
+            let lookahead = ahead.lookahead1();
+            let mut item = if lookahead.peek(Token![fn]) || peek_signature(&ahead) {
+                input.parse().map(TraitItem::Method)
+            } else if lookahead.peek(Token![const]) {
+                ahead.parse::<Token![const]>()?;
+                let lookahead = ahead.lookahead1();
+                if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                    input.parse().map(TraitItem::Const)
+                } else if lookahead.peek(Token![async])
+                    || lookahead.peek(Token![unsafe])
+                    || lookahead.peek(Token![extern])
+                    || lookahead.peek(Token![fn])
+                {
+                    input.parse().map(TraitItem::Method)
+                } else {
+                    Err(lookahead.error())
+                }
+            } else if lookahead.peek(Token![type]) {
+                parse_trait_item_type(begin.fork(), input)
+            } else if lookahead.peek(Ident)
+                || lookahead.peek(Token![self])
+                || lookahead.peek(Token![super])
+                || lookahead.peek(Token![crate])
+                || lookahead.peek(Token![::])
+            {
+                input.parse().map(TraitItem::Macro)
+            } else {
+                Err(lookahead.error())
+            }?;
+
+            match (vis, defaultness) {
+                (Visibility::Inherited, None) => {}
+                _ => return Ok(TraitItem::Verbatim(verbatim::between(begin, input))),
+            }
+
+            let item_attrs = match &mut item {
+                TraitItem::Const(item) => &mut item.attrs,
+                TraitItem::Method(item) => &mut item.attrs,
+                TraitItem::Type(item) => &mut item.attrs,
+                TraitItem::Macro(item) => &mut item.attrs,
+                TraitItem::Verbatim(_) => unreachable!(),
+
+                #[cfg(syn_no_non_exhaustive)]
+                _ => unreachable!(),
+            };
+            attrs.append(item_attrs);
+            *item_attrs = attrs;
+            Ok(item)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TraitItemConst {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(TraitItemConst {
+                attrs: input.call(Attribute::parse_outer)?,
+                const_token: input.parse()?,
+                ident: {
+                    let lookahead = input.lookahead1();
+                    if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                        input.call(Ident::parse_any)?
+                    } else {
+                        return Err(lookahead.error());
+                    }
+                },
+                colon_token: input.parse()?,
+                ty: input.parse()?,
+                default: {
+                    if input.peek(Token![=]) {
+                        let eq_token: Token![=] = input.parse()?;
+                        let default: Expr = input.parse()?;
+                        Some((eq_token, default))
+                    } else {
+                        None
+                    }
+                },
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TraitItemMethod {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let sig: Signature = input.parse()?;
+
+            let lookahead = input.lookahead1();
+            let (brace_token, stmts, semi_token) = if lookahead.peek(token::Brace) {
+                let content;
+                let brace_token = braced!(content in input);
+                attr::parsing::parse_inner(&content, &mut attrs)?;
+                let stmts = content.call(Block::parse_within)?;
+                (Some(brace_token), stmts, None)
+            } else if lookahead.peek(Token![;]) {
+                let semi_token: Token![;] = input.parse()?;
+                (None, Vec::new(), Some(semi_token))
+            } else {
+                return Err(lookahead.error());
+            };
+
+            Ok(TraitItemMethod {
+                attrs,
+                sig,
+                default: brace_token.map(|brace_token| Block { brace_token, stmts }),
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TraitItemType {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let type_token: Token![type] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let mut generics: Generics = input.parse()?;
+            let colon_token: Option<Token![:]> = input.parse()?;
+
+            let mut bounds = Punctuated::new();
+            if colon_token.is_some() {
+                while !input.peek(Token![where]) && !input.peek(Token![=]) && !input.peek(Token![;])
+                {
+                    if !bounds.is_empty() {
+                        bounds.push_punct(input.parse()?);
+                    }
+                    bounds.push_value(input.parse()?);
+                }
+            }
+
+            let default = if input.peek(Token![=]) {
+                let eq_token: Token![=] = input.parse()?;
+                let default: Type = input.parse()?;
+                Some((eq_token, default))
+            } else {
+                None
+            };
+
+            generics.where_clause = input.parse()?;
+            let semi_token: Token![;] = input.parse()?;
+
+            Ok(TraitItemType {
+                attrs,
+                type_token,
+                ident,
+                generics,
+                colon_token,
+                bounds,
+                default,
+                semi_token,
+            })
+        }
+    }
+
+    fn parse_trait_item_type(begin: ParseBuffer, input: ParseStream) -> Result<TraitItem> {
+        let FlexibleItemType {
+            vis,
+            defaultness,
+            type_token,
+            ident,
+            generics,
+            colon_token,
+            bounds,
+            ty,
+            semi_token,
+        } = FlexibleItemType::parse(input, WhereClauseLocation::Both)?;
+
+        if defaultness.is_some() || vis.is_some() {
+            Ok(TraitItem::Verbatim(verbatim::between(begin, input)))
+        } else {
+            Ok(TraitItem::Type(TraitItemType {
+                attrs: Vec::new(),
+                type_token,
+                ident,
+                generics,
+                colon_token,
+                bounds,
+                default: ty,
+                semi_token,
+            }))
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TraitItemMacro {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let mac: Macro = input.parse()?;
+            let semi_token: Option<Token![;]> = if mac.delimiter.is_brace() {
+                None
+            } else {
+                Some(input.parse()?)
+            };
+            Ok(TraitItemMacro {
+                attrs,
+                mac,
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemImpl {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_verbatim_impl = false;
+            parse_impl(input, allow_verbatim_impl).map(Option::unwrap)
+        }
+    }
+
+    fn parse_impl(input: ParseStream, allow_verbatim_impl: bool) -> Result<Option<ItemImpl>> {
+        let mut attrs = input.call(Attribute::parse_outer)?;
+        let has_visibility = allow_verbatim_impl && input.parse::<Visibility>()?.is_some();
+        let defaultness: Option<Token![default]> = input.parse()?;
+        let unsafety: Option<Token![unsafe]> = input.parse()?;
+        let impl_token: Token![impl] = input.parse()?;
+
+        let has_generics = input.peek(Token![<])
+            && (input.peek2(Token![>])
+                || input.peek2(Token![#])
+                || (input.peek2(Ident) || input.peek2(Lifetime))
+                    && (input.peek3(Token![:])
+                        || input.peek3(Token![,])
+                        || input.peek3(Token![>])
+                        || input.peek3(Token![=]))
+                || input.peek2(Token![const]));
+        let mut generics: Generics = if has_generics {
+            input.parse()?
+        } else {
+            Generics::default()
+        };
+
+        let is_const_impl = allow_verbatim_impl
+            && (input.peek(Token![const]) || input.peek(Token![?]) && input.peek2(Token![const]));
+        if is_const_impl {
+            input.parse::<Option<Token![?]>>()?;
+            input.parse::<Token![const]>()?;
+        }
+
+        let begin = input.fork();
+        let polarity = if input.peek(Token![!]) && !input.peek2(token::Brace) {
+            Some(input.parse::<Token![!]>()?)
+        } else {
+            None
+        };
+
+        #[cfg(not(feature = "printing"))]
+        let first_ty_span = input.span();
+        let mut first_ty: Type = input.parse()?;
+        let self_ty: Type;
+        let trait_;
+
+        let is_impl_for = input.peek(Token![for]);
+        if is_impl_for {
+            let for_token: Token![for] = input.parse()?;
+            let mut first_ty_ref = &first_ty;
+            while let Type::Group(ty) = first_ty_ref {
+                first_ty_ref = &ty.elem;
+            }
+            if let Type::Path(TypePath { qself: None, .. }) = first_ty_ref {
+                while let Type::Group(ty) = first_ty {
+                    first_ty = *ty.elem;
+                }
+                if let Type::Path(TypePath { qself: None, path }) = first_ty {
+                    trait_ = Some((polarity, path, for_token));
+                } else {
+                    unreachable!();
+                }
+            } else if !allow_verbatim_impl {
+                #[cfg(feature = "printing")]
+                return Err(Error::new_spanned(first_ty_ref, "expected trait path"));
+                #[cfg(not(feature = "printing"))]
+                return Err(Error::new(first_ty_span, "expected trait path"));
+            } else {
+                trait_ = None;
+            }
+            self_ty = input.parse()?;
+        } else {
+            trait_ = None;
+            self_ty = if polarity.is_none() {
+                first_ty
+            } else {
+                Type::Verbatim(verbatim::between(begin, input))
+            };
+        }
+
+        generics.where_clause = input.parse()?;
+
+        let content;
+        let brace_token = braced!(content in input);
+        attr::parsing::parse_inner(&content, &mut attrs)?;
+
+        let mut items = Vec::new();
+        while !content.is_empty() {
+            items.push(content.parse()?);
+        }
+
+        if has_visibility || is_const_impl || is_impl_for && trait_.is_none() {
+            Ok(None)
+        } else {
+            Ok(Some(ItemImpl {
+                attrs,
+                defaultness,
+                unsafety,
+                impl_token,
+                generics,
+                trait_,
+                self_ty: Box::new(self_ty),
+                brace_token,
+                items,
+            }))
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ImplItem {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let ahead = input.fork();
+            let vis: Visibility = ahead.parse()?;
+
+            let mut lookahead = ahead.lookahead1();
+            let defaultness = if lookahead.peek(Token![default]) && !ahead.peek2(Token![!]) {
+                let defaultness: Token![default] = ahead.parse()?;
+                lookahead = ahead.lookahead1();
+                Some(defaultness)
+            } else {
+                None
+            };
+
+            let mut item = if lookahead.peek(Token![fn]) || peek_signature(&ahead) {
+                input.parse().map(ImplItem::Method)
+            } else if lookahead.peek(Token![const]) {
+                let const_token: Token![const] = ahead.parse()?;
+                let lookahead = ahead.lookahead1();
+                if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                    input.advance_to(&ahead);
+                    let ident: Ident = input.call(Ident::parse_any)?;
+                    let colon_token: Token![:] = input.parse()?;
+                    let ty: Type = input.parse()?;
+                    if let Some(eq_token) = input.parse()? {
+                        return Ok(ImplItem::Const(ImplItemConst {
+                            attrs,
+                            vis,
+                            defaultness,
+                            const_token,
+                            ident,
+                            colon_token,
+                            ty,
+                            eq_token,
+                            expr: input.parse()?,
+                            semi_token: input.parse()?,
+                        }));
+                    } else {
+                        input.parse::<Token![;]>()?;
+                        return Ok(ImplItem::Verbatim(verbatim::between(begin, input)));
+                    }
+                } else {
+                    Err(lookahead.error())
+                }
+            } else if lookahead.peek(Token![type]) {
+                parse_impl_item_type(begin, input)
+            } else if vis.is_inherited()
+                && defaultness.is_none()
+                && (lookahead.peek(Ident)
+                    || lookahead.peek(Token![self])
+                    || lookahead.peek(Token![super])
+                    || lookahead.peek(Token![crate])
+                    || lookahead.peek(Token![::]))
+            {
+                input.parse().map(ImplItem::Macro)
+            } else {
+                Err(lookahead.error())
+            }?;
+
+            {
+                let item_attrs = match &mut item {
+                    ImplItem::Const(item) => &mut item.attrs,
+                    ImplItem::Method(item) => &mut item.attrs,
+                    ImplItem::Type(item) => &mut item.attrs,
+                    ImplItem::Macro(item) => &mut item.attrs,
+                    ImplItem::Verbatim(_) => return Ok(item),
+
+                    #[cfg(syn_no_non_exhaustive)]
+                    _ => unreachable!(),
+                };
+                attrs.append(item_attrs);
+                *item_attrs = attrs;
+            }
+
+            Ok(item)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ImplItemConst {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ImplItemConst {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                defaultness: input.parse()?,
+                const_token: input.parse()?,
+                ident: {
+                    let lookahead = input.lookahead1();
+                    if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                        input.call(Ident::parse_any)?
+                    } else {
+                        return Err(lookahead.error());
+                    }
+                },
+                colon_token: input.parse()?,
+                ty: input.parse()?,
+                eq_token: input.parse()?,
+                expr: input.parse()?,
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ImplItemMethod {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let defaultness: Option<Token![default]> = input.parse()?;
+            let sig: Signature = input.parse()?;
+
+            let block = if let Some(semi) = input.parse::<Option<Token![;]>>()? {
+                // Accept methods without a body in an impl block because
+                // rustc's *parser* does not reject them (the compilation error
+                // is emitted later than parsing) and it can be useful for macro
+                // DSLs.
+                let mut punct = Punct::new(';', Spacing::Alone);
+                punct.set_span(semi.span);
+                let tokens = TokenStream::from_iter(vec![TokenTree::Punct(punct)]);
+                Block {
+                    brace_token: Brace { span: semi.span },
+                    stmts: vec![Stmt::Item(Item::Verbatim(tokens))],
+                }
+            } else {
+                let content;
+                let brace_token = braced!(content in input);
+                attrs.extend(content.call(Attribute::parse_inner)?);
+                Block {
+                    brace_token,
+                    stmts: content.call(Block::parse_within)?,
+                }
+            };
+
+            Ok(ImplItemMethod {
+                attrs,
+                vis,
+                defaultness,
+                sig,
+                block,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ImplItemType {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let defaultness: Option<Token![default]> = input.parse()?;
+            let type_token: Token![type] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let mut generics: Generics = input.parse()?;
+            let eq_token: Token![=] = input.parse()?;
+            let ty: Type = input.parse()?;
+            generics.where_clause = input.parse()?;
+            let semi_token: Token![;] = input.parse()?;
+            Ok(ImplItemType {
+                attrs,
+                vis,
+                defaultness,
+                type_token,
+                ident,
+                generics,
+                eq_token,
+                ty,
+                semi_token,
+            })
+        }
+    }
+
+    fn parse_impl_item_type(begin: ParseBuffer, input: ParseStream) -> Result<ImplItem> {
+        let FlexibleItemType {
+            vis,
+            defaultness,
+            type_token,
+            ident,
+            generics,
+            colon_token,
+            bounds: _,
+            ty,
+            semi_token,
+        } = FlexibleItemType::parse(input, WhereClauseLocation::Both)?;
+
+        if colon_token.is_some() || ty.is_none() {
+            Ok(ImplItem::Verbatim(verbatim::between(begin, input)))
+        } else {
+            let (eq_token, ty) = ty.unwrap();
+            Ok(ImplItem::Type(ImplItemType {
+                attrs: Vec::new(),
+                vis,
+                defaultness,
+                type_token,
+                ident,
+                generics,
+                eq_token,
+                ty,
+                semi_token,
+            }))
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ImplItemMacro {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let mac: Macro = input.parse()?;
+            let semi_token: Option<Token![;]> = if mac.delimiter.is_brace() {
+                None
+            } else {
+                Some(input.parse()?)
+            };
+            Ok(ImplItemMacro {
+                attrs,
+                mac,
+                semi_token,
+            })
+        }
+    }
+
+    impl Visibility {
+        fn is_inherited(&self) -> bool {
+            match *self {
+                Visibility::Inherited => true,
+                _ => false,
+            }
+        }
+    }
+
+    impl MacroDelimiter {
+        fn is_brace(&self) -> bool {
+            match *self {
+                MacroDelimiter::Brace(_) => true,
+                MacroDelimiter::Paren(_) | MacroDelimiter::Bracket(_) => false,
+            }
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use super::*;
+    use crate::attr::FilterAttrs;
+    use crate::print::TokensOrDefault;
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemExternCrate {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.extern_token.to_tokens(tokens);
+            self.crate_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            if let Some((as_token, rename)) = &self.rename {
+                as_token.to_tokens(tokens);
+                rename.to_tokens(tokens);
+            }
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemUse {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.use_token.to_tokens(tokens);
+            self.leading_colon.to_tokens(tokens);
+            self.tree.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemStatic {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.static_token.to_tokens(tokens);
+            self.mutability.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.expr.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemConst {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.const_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.expr.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemFn {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.sig.to_tokens(tokens);
+            self.block.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(self.attrs.inner());
+                tokens.append_all(&self.block.stmts);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemMod {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.mod_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            if let Some((brace, items)) = &self.content {
+                brace.surround(tokens, |tokens| {
+                    tokens.append_all(self.attrs.inner());
+                    tokens.append_all(items);
+                });
+            } else {
+                TokensOrDefault(&self.semi).to_tokens(tokens);
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemForeignMod {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.abi.to_tokens(tokens);
+            self.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(self.attrs.inner());
+                tokens.append_all(&self.items);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.type_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemEnum {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.enum_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.brace_token.surround(tokens, |tokens| {
+                self.variants.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemStruct {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.struct_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            match &self.fields {
+                Fields::Named(fields) => {
+                    self.generics.where_clause.to_tokens(tokens);
+                    fields.to_tokens(tokens);
+                }
+                Fields::Unnamed(fields) => {
+                    fields.to_tokens(tokens);
+                    self.generics.where_clause.to_tokens(tokens);
+                    TokensOrDefault(&self.semi_token).to_tokens(tokens);
+                }
+                Fields::Unit => {
+                    self.generics.where_clause.to_tokens(tokens);
+                    TokensOrDefault(&self.semi_token).to_tokens(tokens);
+                }
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemUnion {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.union_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.fields.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemTrait {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.unsafety.to_tokens(tokens);
+            self.auto_token.to_tokens(tokens);
+            self.trait_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            if !self.supertraits.is_empty() {
+                TokensOrDefault(&self.colon_token).to_tokens(tokens);
+                self.supertraits.to_tokens(tokens);
+            }
+            self.generics.where_clause.to_tokens(tokens);
+            self.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(self.attrs.inner());
+                tokens.append_all(&self.items);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemTraitAlias {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.trait_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.bounds.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemImpl {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.defaultness.to_tokens(tokens);
+            self.unsafety.to_tokens(tokens);
+            self.impl_token.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            if let Some((polarity, path, for_token)) = &self.trait_ {
+                polarity.to_tokens(tokens);
+                path.to_tokens(tokens);
+                for_token.to_tokens(tokens);
+            }
+            self.self_ty.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(self.attrs.inner());
+                tokens.append_all(&self.items);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemMacro {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.mac.path.to_tokens(tokens);
+            self.mac.bang_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            match &self.mac.delimiter {
+                MacroDelimiter::Paren(paren) => {
+                    paren.surround(tokens, |tokens| self.mac.tokens.to_tokens(tokens));
+                }
+                MacroDelimiter::Brace(brace) => {
+                    brace.surround(tokens, |tokens| self.mac.tokens.to_tokens(tokens));
+                }
+                MacroDelimiter::Bracket(bracket) => {
+                    bracket.surround(tokens, |tokens| self.mac.tokens.to_tokens(tokens));
+                }
+            }
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemMacro2 {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.macro_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.rules.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for UsePath {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.ident.to_tokens(tokens);
+            self.colon2_token.to_tokens(tokens);
+            self.tree.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for UseName {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.ident.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for UseRename {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.ident.to_tokens(tokens);
+            self.as_token.to_tokens(tokens);
+            self.rename.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for UseGlob {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.star_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for UseGroup {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.brace_token.surround(tokens, |tokens| {
+                self.items.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TraitItemConst {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.const_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            if let Some((eq_token, default)) = &self.default {
+                eq_token.to_tokens(tokens);
+                default.to_tokens(tokens);
+            }
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TraitItemMethod {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.sig.to_tokens(tokens);
+            match &self.default {
+                Some(block) => {
+                    block.brace_token.surround(tokens, |tokens| {
+                        tokens.append_all(self.attrs.inner());
+                        tokens.append_all(&block.stmts);
+                    });
+                }
+                None => {
+                    TokensOrDefault(&self.semi_token).to_tokens(tokens);
+                }
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TraitItemType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.type_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            if !self.bounds.is_empty() {
+                TokensOrDefault(&self.colon_token).to_tokens(tokens);
+                self.bounds.to_tokens(tokens);
+            }
+            if let Some((eq_token, default)) = &self.default {
+                eq_token.to_tokens(tokens);
+                default.to_tokens(tokens);
+            }
+            self.generics.where_clause.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TraitItemMacro {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.mac.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ImplItemConst {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.defaultness.to_tokens(tokens);
+            self.const_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.expr.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ImplItemMethod {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.defaultness.to_tokens(tokens);
+            self.sig.to_tokens(tokens);
+            if self.block.stmts.len() == 1 {
+                if let Stmt::Item(Item::Verbatim(verbatim)) = &self.block.stmts[0] {
+                    if verbatim.to_string() == ";" {
+                        verbatim.to_tokens(tokens);
+                        return;
+                    }
+                }
+            }
+            self.block.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(self.attrs.inner());
+                tokens.append_all(&self.block.stmts);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ImplItemType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.defaultness.to_tokens(tokens);
+            self.type_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ImplItemMacro {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.mac.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ForeignItemFn {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.sig.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ForeignItemStatic {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.static_token.to_tokens(tokens);
+            self.mutability.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ForeignItemType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.type_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ForeignItemMacro {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.mac.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    fn maybe_variadic_to_tokens(arg: &FnArg, tokens: &mut TokenStream) -> bool {
+        let arg = match arg {
+            FnArg::Typed(arg) => arg,
+            FnArg::Receiver(receiver) => {
+                receiver.to_tokens(tokens);
+                return false;
+            }
+        };
+
+        match arg.ty.as_ref() {
+            Type::Verbatim(ty) if ty.to_string() == "..." => {
+                match arg.pat.as_ref() {
+                    Pat::Verbatim(pat) if pat.to_string() == "..." => {
+                        tokens.append_all(arg.attrs.outer());
+                        pat.to_tokens(tokens);
+                    }
+                    _ => arg.to_tokens(tokens),
+                }
+                true
+            }
+            _ => {
+                arg.to_tokens(tokens);
+                false
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Signature {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.constness.to_tokens(tokens);
+            self.asyncness.to_tokens(tokens);
+            self.unsafety.to_tokens(tokens);
+            self.abi.to_tokens(tokens);
+            self.fn_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.paren_token.surround(tokens, |tokens| {
+                let mut last_is_variadic = false;
+                for pair in self.inputs.pairs() {
+                    last_is_variadic = maybe_variadic_to_tokens(pair.value(), tokens);
+                    pair.punct().to_tokens(tokens);
+                }
+                if self.variadic.is_some() && !last_is_variadic {
+                    if !self.inputs.empty_or_trailing() {
+                        <Token![,]>::default().to_tokens(tokens);
+                    }
+                    self.variadic.to_tokens(tokens);
+                }
+            });
+            self.output.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Receiver {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            if let Some((ampersand, lifetime)) = &self.reference {
+                ampersand.to_tokens(tokens);
+                lifetime.to_tokens(tokens);
+            }
+            self.mutability.to_tokens(tokens);
+            self.self_token.to_tokens(tokens);
+        }
+    }
+}