# syn::parse::Nothing - Rust
API documentation for the Rust `Nothing` struct in crate `syn`.
Keywords: rust, rustlang, rust-lang, Nothing

# [−] [src] Struct syn::parse::Nothing

    pub struct Nothing;

An empty syntax tree node that consumes no tokens when parsed.

This is useful for attribute macros that want to ensure they are not provided any attribute args.

    use proc_macro::TokenStream;
    use syn::parse_macro_input;
    use syn::parse::Nothing;

    #[proc_macro_attribute]
    pub fn my_attr(args: TokenStream, input: TokenStream) -> TokenStream {
        parse_macro_input!(args as Nothing);

        /* ... */
    }

    error: unexpected token
     --> src/main.rs:3:19
      |
    3 | #[my_attr(asdf)]
      |           ^^^^

## Trait Implementations

### `impl Parse for Nothing` [src]

#### `fn parse(_input: ParseStream<'_>) -> Result<Self>` [src]

## Auto Trait Implementations

### `impl RefUnwindSafe for Nothing` [src]

### `impl Send for Nothing` [src]

### `impl Sync for Nothing` [src]

### `impl Unpin for Nothing` [src]

### `impl UnwindSafe for Nothing` [src]

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &T` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut T` [src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T` [src]

#### `pub fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U` [src]

Performs the conversion.

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.