Macro lib::never_impl

macro_rules! never_impl {
    {
        $(#[$attr:meta])*
        $vis:vis fn $method:ident
        $(<
            $($($a:lifetime),+$(,)?)?
            $($TParam:ident),*$(,)?
        >)?(
            &self$(,$($value:ident: $T:ty),*$(,)?)?
        ) $(-> $Returns:ty)? $(where $($wherett:tt)*)?$(;)?
    } => { ... };
    {
        $(#[$attr:meta])*
        $vis:vis unsafe fn $method:ident
        $(<
            $($($a:lifetime),+$(,)?)?
            $($TParam:ident),*$(,)?
        >)?(
            &self$(,$($value:ident: $T:ty),*$(,)?)?
        ) $(-> $Returns:ty)? $(where $($wherett:tt)*)?$(;)?
    } => { ... };
    {
        $(#[$attr:meta])*
        $vis:vis fn $method:ident
        $(<
            $($($a:lifetime),+$(,)?)?
            $($TParam:ident),*$(,)?
        >)?(
            &mut self$(,$($value:ident: $T:ty),*$(,)?)?
        ) $(-> $Returns:ty)? $(where $($wherett:tt)*)?$(;)?
    } => { ... };
    {
        $(#[$attr:meta])*
        $vis:vis unsafe fn $method:ident
        $(<
            $($($a:lifetime),+$(,)?)?
            $($TParam:ident),*$(,)?
        >)?(
            &mut self$(,$($value:ident: $T:ty),*$(,)?)?
        ) $(-> $Returns:ty)? $(where $($wherett:tt)*)?$(;)?
    } => { ... };
}