bjoernager/rust
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Split StableCompare trait out of StableOrd trait.

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StableCompare is a companion trait to `StableOrd`. Some types like `Symbol` can be compared in a cross-session stable way, but their `Ord` implementation is not stable. In such cases, a `StableOrd` implementation can be provided to offer a lightweight way for stable sorting. (The more heavyweight option is to sort via `ToStableHashKey`, but then sorting needs to have access to a stable hashing context and `ToStableHashKey` can also be expensive as in the case of `Symbol` where it has to allocate a `String`.)
This commit is contained in:
Michael Woerister 2023-12-21 10:27:34 +01:00
parent 090d5eac72
commit 739e5ef49e
9 changed files with 118 additions and 22 deletions
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12
compiler/rustc_lint_defs/src/lib.rs
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@ -9,7 +9,9 @@ pub use self::Level::*;
use rustc_ast::node_id::NodeId;
use rustc_ast::{AttrId, Attribute};
use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
use rustc_data_structures::stable_hasher::{
HashStable, StableCompare, StableHasher, ToStableHashKey,
};
use rustc_error_messages::{DiagnosticMessage, MultiSpan};
use rustc_hir::HashStableContext;
use rustc_hir::HirId;
@ -541,6 +543,14 @@ impl<HCX> ToStableHashKey<HCX> for LintId {
}
}
impl StableCompare for LintId {
const CAN_USE_UNSTABLE_SORT: bool = true;
fn stable_cmp(&self, other: &Self) -> std::cmp::Ordering {
self.lint_name_raw().cmp(&other.lint_name_raw())
}
}
#[derive(Debug)]
pub struct AmbiguityErrorDiag {
pub msg: String,