Stop sorting via DefIds in region resolution

compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs

@@ -139,8 +139,8 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
         let mut var_data = self.construct_var_data();
 
         // Deduplicating constraints is shown to have a positive perf impact.
-        self.data.constraints.sort_by_key(|(constraint, _)| *constraint);
-        self.data.constraints.dedup_by_key(|(constraint, _)| *constraint);
+        let mut seen = FxHashSet::default();
+        self.data.constraints.retain(|(constraint, _)| seen.insert(*constraint));
 
         if cfg!(debug_assertions) {
             self.dump_constraints();
@@ -888,12 +888,14 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
                     }
 
                     Constraint::RegSubVar(region, _) | Constraint::VarSubReg(_, region) => {
-                        let constraint_idx =
-                            this.constraints.binary_search_by(|(c, _)| c.cmp(&edge.data)).unwrap();
-                        state.result.push(RegionAndOrigin {
-                            region,
-                            origin: this.constraints[constraint_idx].1.clone(),
-                        });
+                        let origin = this
+                            .constraints
+                            .iter()
+                            .find(|(c, _)| *c == edge.data)
+                            .unwrap()
+                            .1
+                            .clone();
+                        state.result.push(RegionAndOrigin { region, origin });
                     }
 
                     Constraint::RegSubReg(..) => panic!(

compiler/rustc_infer/src/infer/region_constraints/mod.rs

@@ -104,7 +104,7 @@ pub struct RegionConstraintData<'tcx> {
 }
 
 /// Represents a constraint that influences the inference process.
-#[derive(Clone, Copy, PartialEq, Eq, Debug, PartialOrd, Ord)]
+#[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
 pub enum Constraint<'tcx> {
     /// A region variable is a subregion of another.
     VarSubVar(RegionVid, RegionVid),

tests/ui/issues/issue-27942.stderr

@@ -6,16 +6,16 @@ LL |     fn select(&self) -> BufferViewHandle<R>;
    |
    = note: expected trait `Resources<'_>`
               found trait `Resources<'a>`
-note: the anonymous lifetime defined here...
-  --> $DIR/issue-27942.rs:5:15
-   |
-LL |     fn select(&self) -> BufferViewHandle<R>;
-   |               ^^^^^
-note: ...does not necessarily outlive the lifetime `'a` as defined here
+note: the lifetime `'a` as defined here...
   --> $DIR/issue-27942.rs:3:18
    |
 LL | pub trait Buffer<'a, R: Resources<'a>> {
    |                  ^^
+note: ...does not necessarily outlive the anonymous lifetime defined here
+  --> $DIR/issue-27942.rs:5:15
+   |
+LL |     fn select(&self) -> BufferViewHandle<R>;
+   |               ^^^^^
 
 error[E0308]: mismatched types
   --> $DIR/issue-27942.rs:5:25
@@ -25,16 +25,16 @@ LL |     fn select(&self) -> BufferViewHandle<R>;
    |
    = note: expected trait `Resources<'_>`
               found trait `Resources<'a>`
-note: the lifetime `'a` as defined here...
-  --> $DIR/issue-27942.rs:3:18
-   |
-LL | pub trait Buffer<'a, R: Resources<'a>> {
-   |                  ^^
-note: ...does not necessarily outlive the anonymous lifetime defined here
+note: the anonymous lifetime defined here...
   --> $DIR/issue-27942.rs:5:15
    |
 LL |     fn select(&self) -> BufferViewHandle<R>;
    |               ^^^^^
+note: ...does not necessarily outlive the lifetime `'a` as defined here
+  --> $DIR/issue-27942.rs:3:18
+   |
+LL | pub trait Buffer<'a, R: Resources<'a>> {
+   |                  ^^
 
 error: aborting due to 2 previous errors
 

tests/ui/traits/impl-of-supertrait-has-wrong-lifetime-parameters.stderr

@@ -4,16 +4,16 @@ error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'b` d
 LL | impl<'a,'b> T2<'a, 'b> for S<'a, 'b> {
    |                            ^^^^^^^^^
    |
-note: first, the lifetime cannot outlive the lifetime `'a` as defined here...
-  --> $DIR/impl-of-supertrait-has-wrong-lifetime-parameters.rs:24:6
-   |
-LL | impl<'a,'b> T2<'a, 'b> for S<'a, 'b> {
-   |      ^^
-note: ...but the lifetime must also be valid for the lifetime `'b` as defined here...
+note: first, the lifetime cannot outlive the lifetime `'b` as defined here...
   --> $DIR/impl-of-supertrait-has-wrong-lifetime-parameters.rs:24:9
    |
 LL | impl<'a,'b> T2<'a, 'b> for S<'a, 'b> {
    |         ^^
+note: ...but the lifetime must also be valid for the lifetime `'a` as defined here...
+  --> $DIR/impl-of-supertrait-has-wrong-lifetime-parameters.rs:24:6
+   |
+LL | impl<'a,'b> T2<'a, 'b> for S<'a, 'b> {
+   |      ^^
 note: ...so that the types are compatible
   --> $DIR/impl-of-supertrait-has-wrong-lifetime-parameters.rs:24:28
    |

tests/ui/traits/matching-lifetimes.stderr

@@ -6,16 +6,16 @@ LL |     fn foo(x: Foo<'b,'a>) {
    |
    = note: expected signature `fn(Foo<'a, 'b>)`
               found signature `fn(Foo<'b, 'a>)`
-note: the lifetime `'b` as defined here...
-  --> $DIR/matching-lifetimes.rs:13:9
-   |
-LL | impl<'a,'b> Tr for Foo<'a,'b> {
-   |         ^^
-note: ...does not necessarily outlive the lifetime `'a` as defined here
+note: the lifetime `'a` as defined here...
   --> $DIR/matching-lifetimes.rs:13:6
    |
 LL | impl<'a,'b> Tr for Foo<'a,'b> {
    |      ^^
+note: ...does not necessarily outlive the lifetime `'b` as defined here
+  --> $DIR/matching-lifetimes.rs:13:9
+   |
+LL | impl<'a,'b> Tr for Foo<'a,'b> {
+   |         ^^
 
 error[E0308]: method not compatible with trait
   --> $DIR/matching-lifetimes.rs:14:5
@@ -25,16 +25,16 @@ LL |     fn foo(x: Foo<'b,'a>) {
    |
    = note: expected signature `fn(Foo<'a, 'b>)`
               found signature `fn(Foo<'b, 'a>)`
-note: the lifetime `'a` as defined here...
-  --> $DIR/matching-lifetimes.rs:13:6
-   |
-LL | impl<'a,'b> Tr for Foo<'a,'b> {
-   |      ^^
-note: ...does not necessarily outlive the lifetime `'b` as defined here
+note: the lifetime `'b` as defined here...
   --> $DIR/matching-lifetimes.rs:13:9
    |
 LL | impl<'a,'b> Tr for Foo<'a,'b> {
    |         ^^
+note: ...does not necessarily outlive the lifetime `'a` as defined here
+  --> $DIR/matching-lifetimes.rs:13:6
+   |
+LL | impl<'a,'b> Tr for Foo<'a,'b> {
+   |      ^^
 
 error: aborting due to 2 previous errors