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| -rw-r--r-- | src/librustc_data_structures/indexed_vec.rs | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/src/librustc_data_structures/indexed_vec.rs b/src/librustc_data_structures/indexed_vec.rs index f8992c991cc..09015957f99 100644 --- a/src/librustc_data_structures/indexed_vec.rs +++ b/src/librustc_data_structures/indexed_vec.rs @@ -48,6 +48,13 @@ impl Idx for u32 { fn index(self) -> usize { self as usize } } +/// Creates a struct type `S` that can be used as an index with +/// `IndexVec` and so on. This struct can be constructed via `S::new` +/// (given a `usize`) and converted to a usize with the `index()` +/// method (from the `Idx` trait). 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. #[macro_export] macro_rules! newtype_index { // ---- public rules ---- |