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Add negative impl for Ord, PartialOrd on LocalDefId

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Add comment about why `LocalDefId` should not be `Ord`

Also fix some formatting in the doc comment.
This commit is contained in:
pierwill 2021-12-30 11:01:30 -06:00
parent f8d4ee7c7a
commit 0bac713569
1 changed files with 11 additions and 5 deletions
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16
compiler/rustc_span/src/def_id.rs
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@ -316,17 +316,23 @@ impl fmt::Debug for DefId {
rustc_data_structures::define_id_collections!(DefIdMap, DefIdSet, DefId);
/// A LocalDefId is equivalent to a DefId with `krate == LOCAL_CRATE`. Since
/// A `LocalDefId` is equivalent to a `DefId` with `krate == LOCAL_CRATE`. Since
/// we encode this information in the type, we can ensure at compile time that
/// no DefIds from upstream crates get thrown into the mix. There are quite a
/// few cases where we know that only DefIds from the local crate are expected
/// and a DefId from a different crate would signify a bug somewhere. This
/// is when LocalDefId comes in handy.
/// no `DefId`s from upstream crates get thrown into the mix. There are quite a
/// few cases where we know that only `DefId`s from the local crate are expected;
/// a `DefId` from a different crate would signify a bug somewhere. This
/// is when `LocalDefId` comes in handy.
#[derive(Clone, Copy, PartialEq, Eq, Hash)]
pub struct LocalDefId {
pub local_def_index: DefIndex,
}
// To ensure correctness of incremental compilation,
// `LocalDefId` must not implement `Ord` or `PartialOrd`.
// See https://github.com/rust-lang/rust/issues/90317.
impl !Ord for LocalDefId {}
impl !PartialOrd for LocalDefId {}
pub const CRATE_DEF_ID: LocalDefId = LocalDefId { local_def_index: CRATE_DEF_INDEX };
impl Idx for LocalDefId {