Macro rustc_index::newtype_index

macro_rules! newtype_index {
    ($(#[$attrs:meta])* $v:vis struct $name:ident { .. }) => { ... };
    ($(#[$attrs:meta])* $v:vis struct $name:ident { $($tokens:tt)+ }) => { ... };
    (@derives      [$($derives:ident,)*]
     @attrs        [$(#[$attrs:meta])*]
     @type         [$type:ident]
     @max          [$max:expr]
     @vis          [$v:vis]
     @debug_format [$debug_format:tt]) => { ... };
    (@handle_debug
     @derives      [$($_derives:ident,)*]
     @type         [$type:ident]
     @debug_format [custom]) => { ... };
    (@handle_debug
     @derives      []
     @type         [$type:ident]
     @debug_format [$debug_format:tt]) => { ... };
    (@handle_debug
     @derives      [Debug, $($derives:ident,)*]
     @type         [$type:ident]
     @debug_format [$debug_format:tt]) => { ... };
    (@handle_debug
     @derives      [$_derive:ident, $($derives:ident,)*]
     @type         [$type:ident]
     @debug_format [$debug_format:tt]) => { ... };
    (@attrs        [$(#[$attrs:meta])*]
     @type         [$type:ident]
     @max          [$max:expr]
     @vis          [$v:vis]
     @debug_format [$debug_format:tt]
                   derive [$($derives:ident),*]
                   $($tokens:tt)*) => { ... };
    (@attrs        [$(#[$attrs:meta])*]
     @type         [$type:ident]
     @max          [$max:expr]
     @vis          [$v:vis]
     @debug_format [$debug_format:tt]
                   derive [$($derives:ident,)+]
                   ENCODABLE = custom
                   $($tokens:tt)*) => { ... };
    (@attrs        [$(#[$attrs:meta])*]
     @type         [$type:ident]
     @max          [$max:expr]
     @vis          [$v:vis]
     @debug_format [$debug_format:tt]
                   derive [$($derives:ident,)+]
                   $($tokens:tt)*) => { ... };
    (@attrs        [$(#[$attrs:meta])*]
     @type         [$type:ident]
     @max          [$max:expr]
     @vis          [$v:vis]
     @debug_format [$debug_format:tt]
                   ENCODABLE = custom
                   $($tokens:tt)*) => { ... };
    (@attrs        [$(#[$attrs:meta])*]
     @type         [$type:ident]
     @max          [$max:expr]
     @vis          [$v:vis]
     @debug_format [$debug_format:tt]
                   $($tokens:tt)*) => { ... };
    (@serializable $type:ident) => { ... };
    (@derives      [$($derives:ident,)*]
     @attrs        [$(#[$attrs:meta])*]
     @type         [$type:ident]
     @max          [$max:expr]
     @vis          [$v:vis]
     @debug_format [$debug_format:tt]
                   $name:ident = $constant:expr) => { ... };
    (@derives      [$($derives:ident,)*]
     @attrs        [$(#[$attrs:meta])*]
     @type         [$type:ident]
     @max          [$max:expr]
     @vis          [$v:vis]
     @debug_format [$debug_format:tt]
                   $(#[doc = $doc:expr])*
                   const $name:ident = $constant:expr) => { ... };
    (@derives      [$($derives:ident,)*]
     @attrs        [$(#[$attrs:meta])*]
     @type         [$type:ident]
     @max          [$_max:expr]
     @vis          [$v:vis]
     @debug_format [$debug_format:tt]
                   MAX = $max:expr,
                   $($tokens:tt)*) => { ... };
    (@derives      [$($derives:ident,)*]
     @attrs        [$(#[$attrs:meta])*]
     @type         [$type:ident]
     @max          [$max:expr]
     @vis          [$v:vis]
     @debug_format [$_debug_format:tt]
                   DEBUG_FORMAT = $debug_format:tt,
                   $($tokens:tt)*) => { ... };
    (@derives      [$($derives:ident,)*]
     @attrs        [$(#[$attrs:meta])*]
     @type         [$type:ident]
     @max          [$max:expr]
     @vis          [$v:vis]
     @debug_format [$debug_format:tt]
                   $(#[doc = $doc:expr])*
                   const $name:ident = $constant:expr,
                   $($tokens:tt)*) => { ... };
}

Creates a struct type S that can be used as an index with IndexVec and so on.

There are two ways of interacting with these indices:

• The From impls are the preferred way. So you can do S::from(v) with a usize or u32. And you can convert back to an integer with u32::from(s).

• Alternatively, you can use the methods S::new(v) and s.index() to create/return a value.

Internally, the index uses a u32, so the index must not exceed u32::MAX. You can also customize things like the Debug impl, what traits are derived, and so forth via the macro.