impl !PartialOrd for HirId

Author: oli-obk

compiler/rustc_hir/src/hir_id.rs

@@ -83,6 +83,12 @@ 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 Debug for HirId {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // Example: HirId(DefId(0:1 ~ aa[7697]::{use#0}).10)
@@ -116,10 +122,6 @@ impl HirId {
     pub fn make_owner(owner: LocalDefId) -> Self {
         Self { owner: OwnerId { def_id: owner }, local_id: ItemLocalId::ZERO }
     }
-
-    pub fn index(self) -> (usize, usize) {
-        (rustc_index::Idx::index(self.owner.def_id), rustc_index::Idx::index(self.local_id))
-    }
 }
 
 impl fmt::Display for HirId {
@@ -128,18 +130,6 @@ 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_stable_id_collections!(HirIdMap, HirIdSet, HirIdMapEntry, HirId);
 rustc_data_structures::define_id_collections!(
     ItemLocalMap,

compiler/rustc_hir/src/lib.rs

@@ -11,6 +11,7 @@
 #![feature(debug_closure_helpers)]
 #![feature(exhaustive_patterns)]
 #![feature(let_chains)]
+#![feature(negative_impls)]
 #![feature(never_type)]
 #![feature(rustc_attrs)]
 #![feature(variant_count)]

compiler/rustc_lint_defs/src/lib.rs

@@ -8,7 +8,8 @@ use rustc_data_structures::stable_hasher::{
 };
 use rustc_error_messages::{DiagMessage, MultiSpan};
 use rustc_hir::def::Namespace;
-use rustc_hir::{HashStableContext, HirId, MissingLifetimeKind};
+use rustc_hir::def_id::DefPathHash;
+use rustc_hir::{HashStableContext, HirId, ItemLocalId, MissingLifetimeKind};
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 pub use rustc_span::edition::Edition;
 use rustc_span::{Ident, MacroRulesNormalizedIdent, Span, Symbol, sym};
@@ -102,7 +103,7 @@ 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.
@@ -156,13 +157,14 @@ 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 = (DefPathHash, 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`")

compiler/rustc_passes/src/dead.rs

@@ -1132,7 +1132,8 @@ impl<'tcx> DeadVisitor<'tcx> {
         if dead_codes.is_empty() {
             return;
         }
-        dead_codes.sort_by_key(|v| v.level);
+        // FIXME: `dead_codes` should probably be morally equivalent to `IndexMap<(Level, LintExpectationId), (DefId, Symbol)>`
+        dead_codes.sort_by(|a, b| a.level.0.partial_cmp(&b.level.0).unwrap());
         for group in dead_codes.chunk_by(|a, b| a.level == b.level) {
             self.lint_at_single_level(&group, participle, Some(def_id), report_on);
         }

src/tools/clippy/clippy_lints/src/macro_use.rs

@@ -153,9 +153,15 @@ impl LateLintPass<'_> for MacroUseImports {
                     [] | [_] => return,
                     [root, item] => {
                         if !check_dup.contains(&(*item).to_string()) {
-                            used.entry(((*root).to_string(), span, hir_id))
-                                .or_insert_with(Vec::new)
-                                .push((*item).to_string());
+                            used.entry((
+                                (*root).to_string(),
+                                span,
+                                hir_id.local_id,
+                                cx.tcx.def_path_hash(hir_id.owner.def_id.into()),
+                            ))
+                            .or_insert_with(|| (vec![], hir_id))
+                            .0
+                            .push((*item).to_string());
                             check_dup.push((*item).to_string());
                         }
                     },
@@ -171,15 +177,27 @@ impl LateLintPass<'_> for MacroUseImports {
                                     }
                                 })
                                 .collect::<Vec<_>>();
-                            used.entry(((*root).to_string(), span, hir_id))
-                                .or_insert_with(Vec::new)
-                                .push(filtered.join("::"));
+                            used.entry((
+                                (*root).to_string(),
+                                span,
+                                hir_id.local_id,
+                                cx.tcx.def_path_hash(hir_id.owner.def_id.into()),
+                            ))
+                            .or_insert_with(|| (vec![], hir_id))
+                            .0
+                            .push(filtered.join("::"));
                             check_dup.extend(filtered);
                         } else {
                             let rest = rest.to_vec();
-                            used.entry(((*root).to_string(), span, hir_id))
-                                .or_insert_with(Vec::new)
-                                .push(rest.join("::"));
+                            used.entry((
+                                (*root).to_string(),
+                                span,
+                                hir_id.local_id,
+                                cx.tcx.def_path_hash(hir_id.owner.def_id.into()),
+                            ))
+                            .or_insert_with(|| (vec![], hir_id))
+                            .0
+                            .push(rest.join("::"));
                             check_dup.extend(rest.iter().map(ToString::to_string));
                         }
                     },
@@ -190,7 +208,7 @@ impl LateLintPass<'_> for MacroUseImports {
         // If mac_refs is not empty we have encountered an import we could not handle
         // such as `std::prelude::v1::foo` or some other macro that expands to an import.
         if self.mac_refs.is_empty() {
-            for ((root, span, hir_id), path) in used {
+            for ((root, span, ..), (path, hir_id)) in used {
                 let import = if let [single] = &path[..] {
                     format!("{root}::{single}")
                 } else {