Remove ordering traits from HirId

compiler/rustc_hir/src/hir_id.rs

@@ -19,6 +19,12 @@ pub struct HirId {
     pub local_id: ItemLocalId,
 }
 
+// To ensure correctness of incremental compilation,
+// `HirId` must not implement `Ord` or `PartialOrd`.
+// See https://github.com/rust-lang/rust/issues/90317.
+impl !Ord for HirId {}
+impl !PartialOrd for HirId {}
+
 impl HirId {
     #[inline]
     pub fn expect_owner(self) -> LocalDefId {
@@ -40,10 +46,6 @@ impl HirId {
     pub fn make_owner(owner: LocalDefId) -> Self {
         Self { owner, local_id: ItemLocalId::from_u32(0) }
     }
-
-    pub fn index(self) -> (usize, usize) {
-        (rustc_index::vec::Idx::index(self.owner), rustc_index::vec::Idx::index(self.local_id))
-    }
 }
 
 impl fmt::Display for HirId {
@@ -52,18 +54,6 @@ impl fmt::Display for HirId {
     }
 }
 
-impl Ord for HirId {
-    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-        (self.index()).cmp(&(other.index()))
-    }
-}
-
-impl PartialOrd for HirId {
-    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(&other))
-    }
-}
-
 rustc_data_structures::define_id_collections!(HirIdMap, HirIdSet, HirId);
 rustc_data_structures::define_id_collections!(ItemLocalMap, ItemLocalSet, ItemLocalId);
 

compiler/rustc_hir/src/lib.rs

@@ -8,6 +8,7 @@
 #![feature(let_else)]
 #![feature(once_cell)]
 #![feature(min_specialization)]
+#![feature(negative_impls)]
 #![feature(never_type)]
 #![feature(rustc_attrs)]
 #![recursion_limit = "256"]

compiler/rustc_lint_defs/src/lib.rs

@@ -3,6 +3,8 @@
 #[macro_use]
 extern crate rustc_macros;
 
+use std::cmp::Ordering;
+
 pub use self::Level::*;
 use rustc_ast::node_id::{NodeId, NodeMap};
 use rustc_ast::{AttrId, Attribute};
@@ -80,7 +82,7 @@ pub enum Applicability {
 /// The index values have a type of `u16` to reduce the size of the `LintExpectationId`.
 /// It's reasonable to assume that no user will define 2^16 attributes on one node or
 /// have that amount of lints listed. `u16` values should therefore suffice.
-#[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash, Encodable, Decodable)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug, Hash, Encodable, Decodable)]
 pub enum LintExpectationId {
     /// Used for lints emitted during the `EarlyLintPass`. This id is not
     /// hash stable and should not be cached.
@@ -134,13 +136,14 @@ impl<HCX: rustc_hir::HashStableContext> HashStable<HCX> for LintExpectationId {
 }
 
 impl<HCX: rustc_hir::HashStableContext> ToStableHashKey<HCX> for LintExpectationId {
-    type KeyType = (HirId, u16, u16);
+    type KeyType = (rustc_hir::def_id::DefPathHash, rustc_hir::hir_id::ItemLocalId, u16, u16);
 
     #[inline]
-    fn to_stable_hash_key(&self, _: &HCX) -> Self::KeyType {
+    fn to_stable_hash_key(&self, hcx: &HCX) -> Self::KeyType {
         match self {
             LintExpectationId::Stable { hir_id, attr_index, lint_index: Some(lint_index) } => {
-                (*hir_id, *attr_index, *lint_index)
+                let (def_path_hash, lint_idx) = hir_id.to_stable_hash_key(hcx);
+                (def_path_hash, lint_idx, *attr_index, *lint_index)
             }
             _ => {
                 unreachable!("HashStable should only be called for a filled `LintExpectationId`")
@@ -152,7 +155,7 @@ impl<HCX: rustc_hir::HashStableContext> ToStableHashKey<HCX> for LintExpectation
 /// Setting for how to handle a lint.
 ///
 /// See: <https://doc.rust-lang.org/rustc/lints/levels.html>
-#[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash, HashStable_Generic)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
 pub enum Level {
     /// The `allow` level will not issue any message.
     Allow,
@@ -186,6 +189,14 @@ pub enum Level {
     Forbid,
 }
 
+impl PartialOrd for Level {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        std::mem::discriminant(self).partial_cmp(std::mem::discriminant(other))
+    }
+}
+
+rustc_data_structures::impl_stable_hash_via_hash!(Level);
+
 impl Level {
     /// Converts a level to a lower-case string.
     pub fn as_str(self) -> &'static str {

compiler/rustc_middle/src/mir/query.rs

@@ -350,7 +350,7 @@ rustc_data_structures::static_assert_size!(ConstraintCategory<'_>, 16);
 /// order of the category, thereby influencing diagnostic output.
 ///
 /// See also `rustc_const_eval::borrow_check::constraints`.
-#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash)]
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
 #[derive(TyEncodable, TyDecodable, HashStable)]
 pub enum ConstraintCategory<'tcx> {
     Return(ReturnConstraint),
@@ -392,7 +392,7 @@ pub enum ConstraintCategory<'tcx> {
     Internal,
 }
 
-#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash)]
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
 #[derive(TyEncodable, TyDecodable, HashStable)]
 pub enum ReturnConstraint {
     Normal,

compiler/rustc_typeck/src/check/upvar.rs

@@ -85,7 +85,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 /// Intermediate format to store the hir_id pointing to the use that resulted in the
 /// corresponding place being captured and a String which contains the captured value's
 /// name (i.e: a.b.c)
-#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
 enum UpvarMigrationInfo {
     /// We previously captured all of `x`, but now we capture some sub-path.
     CapturingPrecise { source_expr: Option<hir::HirId>, var_name: String },