Add in ValuePair::Term

This adds in an enum when matching on positions which can either be types or consts.
It will default to emitting old special cased error messages for types.

compiler/rustc_infer/src/infer/at.rs

@@ -288,21 +288,13 @@ impl<'tcx> ToTrace<'tcx> for &'tcx Const<'tcx> {
 
 impl<'tcx> ToTrace<'tcx> for ty::Term<'tcx> {
     fn to_trace(
-        tcx: TyCtxt<'tcx>,
+        _: TyCtxt<'tcx>,
         cause: &ObligationCause<'tcx>,
         a_is_expected: bool,
         a: Self,
         b: Self,
     ) -> TypeTrace<'tcx> {
-        match (a, b) {
-            (ty::Term::Ty(a), ty::Term::Ty(b)) => {
-                ToTrace::to_trace(tcx, cause, a_is_expected, a, b)
-            }
-            (ty::Term::Const(a), ty::Term::Const(b)) => {
-                ToTrace::to_trace(tcx, cause, a_is_expected, a, b)
-            }
-            (_, _) => todo!(),
-        }
+        TypeTrace { cause: cause.clone(), values: Terms(ExpectedFound::new(a_is_expected, a, b)) }
     }
 }
 

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

@@ -2127,6 +2127,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             infer::Types(exp_found) => self.expected_found_str_ty(exp_found),
             infer::Regions(exp_found) => self.expected_found_str(exp_found),
             infer::Consts(exp_found) => self.expected_found_str(exp_found),
+            infer::Terms(exp_found) => self.expected_found_str_term(exp_found),
             infer::TraitRefs(exp_found) => {
                 let pretty_exp_found = ty::error::ExpectedFound {
                     expected: exp_found.expected.print_only_trait_path(),
@@ -2166,6 +2167,24 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         Some(self.cmp(exp_found.expected, exp_found.found))
     }
 
+    fn expected_found_str_term(
+        &self,
+        exp_found: ty::error::ExpectedFound<ty::Term<'tcx>>,
+    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString)> {
+        let exp_found = self.resolve_vars_if_possible(exp_found);
+        if exp_found.references_error() {
+            return None;
+        }
+
+        Some(match (exp_found.expected, exp_found.found) {
+            (ty::Term::Ty(expected), ty::Term::Ty(found)) => self.cmp(expected, found),
+            (expected, found) => (
+                DiagnosticStyledString::highlighted(expected.to_string()),
+                DiagnosticStyledString::highlighted(found.to_string()),
+            ),
+        })
+    }
+
     /// Returns a string of the form "expected `{}`, found `{}`".
     fn expected_found_str<T: fmt::Display + TypeFoldable<'tcx>>(
         &self,

compiler/rustc_infer/src/infer/mod.rs

@@ -371,6 +371,7 @@ pub enum ValuePairs<'tcx> {
     Types(ExpectedFound<Ty<'tcx>>),
     Regions(ExpectedFound<ty::Region<'tcx>>),
     Consts(ExpectedFound<&'tcx ty::Const<'tcx>>),
+    Terms(ExpectedFound<ty::Term<'tcx>>),
     TraitRefs(ExpectedFound<ty::TraitRef<'tcx>>),
     PolyTraitRefs(ExpectedFound<ty::PolyTraitRef<'tcx>>),
 }

src/test/ui/associated-types/higher-ranked-projection.bad.stderr

@@ -4,8 +4,8 @@ error[E0308]: mismatched types
 LL |     foo(());
    |     ^^^ lifetime mismatch
    |
-   = note: expected reference `&'a ()`
-                   found type `&()`
+   = note: expected type `&'a ()`
+              found type `&()`
 note: the lifetime requirement is introduced here
   --> $DIR/higher-ranked-projection.rs:15:33
    |

src/test/ui/lifetimes/issue-79187-2.stderr

@@ -23,8 +23,8 @@ error[E0308]: mismatched types
 LL |     take_foo(|a: &i32| a);
    |     ^^^^^^^^ lifetime mismatch
    |
-   = note: expected reference `&i32`
-              found reference `&i32`
+   = note: expected type `&i32`
+              found type `&i32`
 note: the anonymous lifetime #1 defined here doesn't meet the lifetime requirements
   --> $DIR/issue-79187-2.rs:9:14
    |
@@ -42,8 +42,8 @@ error[E0308]: mismatched types
 LL |     take_foo(|a: &i32| -> &i32 { a });
    |     ^^^^^^^^ lifetime mismatch
    |
-   = note: expected reference `&i32`
-              found reference `&i32`
+   = note: expected type `&i32`
+              found type `&i32`
 note: the anonymous lifetime #1 defined here doesn't meet the lifetime requirements
   --> $DIR/issue-79187-2.rs:10:14
    |