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.