Auto merge of #87648 - JulianKnodt:const_eq_constrain, r=oli-obk

allow eq constraints on associated constants

Updates #70256

(cc `@varkor,` `@Centril)`

28 files changed, 304 insertions, 102 deletions

diff --git a/src/etc/check_missing_items.py b/src/etc/check_missing_items.py
index 7ed317c778f..de1717b3f3f 100644
--- a/src/etc/check_missing_items.py
+++ b/src/etc/check_missing_items.py
@@ -83,7 +83,9 @@ def check_type(ty):
                         check_type(arg["const"]["type"])
                 for binding in args["angle_bracketed"]["bindings"]:
                     if "equality" in binding["binding"]:
-                        check_type(binding["binding"]["equality"])
+                        term = binding["binding"]["equality"]
+                        if "type" in term: check_type(term["type"])
+                        elif "const" in term: check_type(term["const"])
                     elif "constraint" in binding["binding"]:
                         for bound in binding["binding"]["constraint"]:
                             check_generic_bound(bound)
diff --git a/src/librustdoc/clean/auto_trait.rs b/src/librustdoc/clean/auto_trait.rs
index 09692d27e8f..18a4d8a4753 100644
--- a/src/librustdoc/clean/auto_trait.rs
+++ b/src/librustdoc/clean/auto_trait.rs
@@ -553,8 +553,10 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
                             if self.is_fn_trait(trait_) && left_name == sym::Output {
                                 ty_to_fn
                                     .entry(*ty.clone())
-                                    .and_modify(|e| *e = (e.0.clone(), Some(rhs.clone())))
-                                    .or_insert((None, Some(rhs)));
+                                    .and_modify(|e| {
+                                        *e = (e.0.clone(), Some(rhs.ty().unwrap().clone()))
+                                    })
+                                    .or_insert((None, Some(rhs.ty().unwrap().clone())));
                                 continue;
                             }
 
@@ -570,7 +572,7 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
                                 GenericArgs::AngleBracketed { ref mut bindings, .. } => {
                                     bindings.push(TypeBinding {
                                         name: left_name,
-                                        kind: TypeBindingKind::Equality { ty: rhs },
+                                        kind: TypeBindingKind::Equality { term: rhs },
                                     });
                                 }
                                 GenericArgs::Parenthesized { .. } => {
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index a5bc70a74ae..e759baa0458 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -272,9 +272,10 @@ impl Clean<WherePredicate> for hir::WherePredicate<'_> {
                 bounds: wrp.bounds.iter().filter_map(|x| x.clean(cx)).collect(),
             },
 
-            hir::WherePredicate::EqPredicate(ref wrp) => {
-                WherePredicate::EqPredicate { lhs: wrp.lhs_ty.clean(cx), rhs: wrp.rhs_ty.clean(cx) }
-            }
+            hir::WherePredicate::EqPredicate(ref wrp) => WherePredicate::EqPredicate {
+                lhs: wrp.lhs_ty.clean(cx),
+                rhs: wrp.rhs_ty.clean(cx).into(),
+            },
         }
     }
 }
@@ -352,10 +353,31 @@ impl<'tcx> Clean<Option<WherePredicate>> for ty::OutlivesPredicate<Ty<'tcx>, ty:
     }
 }
 
+impl<'tcx> Clean<Term> for ty::Term<'tcx> {
+    fn clean(&self, cx: &mut DocContext<'_>) -> Term {
+        match self {
+            ty::Term::Ty(ty) => Term::Type(ty.clean(cx)),
+            ty::Term::Const(c) => Term::Constant(c.clean(cx)),
+        }
+    }
+}
+
+impl<'tcx> Clean<Term> for hir::Term<'tcx> {
+    fn clean(&self, cx: &mut DocContext<'_>) -> Term {
+        match self {
+            hir::Term::Ty(ty) => Term::Type(ty.clean(cx)),
+            hir::Term::Const(c) => {
+                let def_id = cx.tcx.hir().local_def_id(c.hir_id);
+                Term::Constant(ty::Const::from_anon_const(cx.tcx, def_id).clean(cx))
+            }
+        }
+    }
+}
+
 impl<'tcx> Clean<WherePredicate> for ty::ProjectionPredicate<'tcx> {
     fn clean(&self, cx: &mut DocContext<'_>) -> WherePredicate {
-        let ty::ProjectionPredicate { projection_ty, ty } = self;
-        WherePredicate::EqPredicate { lhs: projection_ty.clean(cx), rhs: ty.clean(cx) }
+        let ty::ProjectionPredicate { projection_ty, term } = self;
+        WherePredicate::EqPredicate { lhs: projection_ty.clean(cx), rhs: term.clean(cx) }
     }
 }
 
@@ -613,7 +635,7 @@ fn clean_ty_generics(
 
             if let Some(param_idx) = param_idx {
                 if let Some(b) = impl_trait.get_mut(&param_idx.into()) {
-                    let p = p.clean(cx)?;
+                    let p: WherePredicate = p.clean(cx)?;
 
                     b.extend(
                         p.get_bounds()
@@ -624,11 +646,16 @@ fn clean_ty_generics(
                     );
 
                     let proj = projection
-                        .map(|p| (p.skip_binder().projection_ty.clean(cx), p.skip_binder().ty));
+                        .map(|p| (p.skip_binder().projection_ty.clean(cx), p.skip_binder().term));
                     if let Some(((_, trait_did, name), rhs)) =
                         proj.as_ref().and_then(|(lhs, rhs)| Some((lhs.projection()?, rhs)))
                     {
-                        impl_trait_proj.entry(param_idx).or_default().push((trait_did, name, rhs));
+                        // FIXME(...): Remove this unwrap()
+                        impl_trait_proj.entry(param_idx).or_default().push((
+                            trait_did,
+                            name,
+                            rhs.ty().unwrap(),
+                        ));
                     }
 
                     return None;
@@ -647,7 +674,7 @@ fn clean_ty_generics(
             if let Some(proj) = impl_trait_proj.remove(&idx) {
                 for (trait_did, name, rhs) in proj {
                     let rhs = rhs.clean(cx);
-                    simplify::merge_bounds(cx, &mut bounds, trait_did, name, &rhs);
+                    simplify::merge_bounds(cx, &mut bounds, trait_did, name, &Term::Type(rhs));
                 }
             }
         } else {
@@ -1495,7 +1522,9 @@ impl<'tcx> Clean<Type> for Ty<'tcx> {
                 for pb in obj.projection_bounds() {
                     bindings.push(TypeBinding {
                         name: cx.tcx.associated_item(pb.item_def_id()).ident.name,
-                        kind: TypeBindingKind::Equality { ty: pb.skip_binder().ty.clean(cx) },
+                        kind: TypeBindingKind::Equality {
+                            term: pb.skip_binder().term.clean(cx).into(),
+                        },
                     });
                 }
 
@@ -1566,7 +1595,7 @@ impl<'tcx> Clean<Type> for Ty<'tcx> {
                                                 .ident
                                                 .name,
                                             kind: TypeBindingKind::Equality {
-                                                ty: proj.ty.clean(cx),
+                                                term: proj.term.clean(cx),
                                             },
                                         })
                                     } else {
@@ -2114,10 +2143,10 @@ impl Clean<TypeBinding> for hir::TypeBinding<'_> {
 impl Clean<TypeBindingKind> for hir::TypeBindingKind<'_> {
     fn clean(&self, cx: &mut DocContext<'_>) -> TypeBindingKind {
         match *self {
-            hir::TypeBindingKind::Equality { ref ty } => {
-                TypeBindingKind::Equality { ty: ty.clean(cx) }
+            hir::TypeBindingKind::Equality { ref term } => {
+                TypeBindingKind::Equality { term: term.clean(cx) }
             }
-            hir::TypeBindingKind::Constraint { bounds } => TypeBindingKind::Constraint {
+            hir::TypeBindingKind::Constraint { ref bounds } => TypeBindingKind::Constraint {
                 bounds: bounds.iter().filter_map(|b| b.clean(cx)).collect(),
             },
         }
diff --git a/src/librustdoc/clean/simplify.rs b/src/librustdoc/clean/simplify.rs
index 4c81e75e8d6..0bad1532808 100644
--- a/src/librustdoc/clean/simplify.rs
+++ b/src/librustdoc/clean/simplify.rs
@@ -92,7 +92,7 @@ crate fn merge_bounds(
     bounds: &mut Vec<clean::GenericBound>,
     trait_did: DefId,
     name: Symbol,
-    rhs: &clean::Type,
+    rhs: &clean::Term,
 ) -> bool {
     !bounds.iter_mut().any(|b| {
         let trait_ref = match *b {
@@ -110,14 +110,14 @@ crate fn merge_bounds(
             PP::AngleBracketed { ref mut bindings, .. } => {
                 bindings.push(clean::TypeBinding {
                     name,
-                    kind: clean::TypeBindingKind::Equality { ty: rhs.clone() },
+                    kind: clean::TypeBindingKind::Equality { term: rhs.clone() },
                 });
             }
             PP::Parenthesized { ref mut output, .. } => match output {
-                Some(o) => assert_eq!(o.as_ref(), rhs),
+                Some(o) => assert_eq!(&clean::Term::Type(o.as_ref().clone()), rhs),
                 None => {
-                    if *rhs != clean::Type::Tuple(Vec::new()) {
-                        *output = Some(Box::new(rhs.clone()));
+                    if *rhs != clean::Term::Type(clean::Type::Tuple(Vec::new())) {
+                        *output = Some(Box::new(rhs.ty().unwrap().clone()));
                     }
                 }
             },
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 00c6e38839f..fac1a0817e0 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -1212,7 +1212,7 @@ impl Lifetime {
 crate enum WherePredicate {
     BoundPredicate { ty: Type, bounds: Vec<GenericBound>, bound_params: Vec<Lifetime> },
     RegionPredicate { lifetime: Lifetime, bounds: Vec<GenericBound> },
-    EqPredicate { lhs: Type, rhs: Type },
+    EqPredicate { lhs: Type, rhs: Term },
 }
 
 impl WherePredicate {
@@ -1308,7 +1308,9 @@ impl FnDecl {
             FnRetTy::Return(Type::ImplTrait(bounds)) => match &bounds[0] {
                 GenericBound::TraitBound(PolyTrait { trait_, .. }, ..) => {
                     let bindings = trait_.bindings().unwrap();
-                    FnRetTy::Return(bindings[0].ty().clone())
+                    let ret_ty = bindings[0].term();
+                    let ty = ret_ty.ty().expect("Unexpected constant return term");
+                    FnRetTy::Return(ty.clone())
                 }
                 _ => panic!("unexpected desugaring of async function"),
             },
@@ -2122,6 +2124,24 @@ crate struct Constant {
 }
 
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
+crate enum Term {
+    Type(Type),
+    Constant(Constant),
+}
+
+impl Term {
+    crate fn ty(&self) -> Option<&Type> {
+        if let Term::Type(ty) = self { Some(ty) } else { None }
+    }
+}
+
+impl From<Type> for Term {
+    fn from(ty: Type) -> Self {
+        Term::Type(ty)
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Hash, Debug)]
 crate enum ConstantKind {
     /// This is the wrapper around `ty::Const` for a non-local constant. Because it doesn't have a
     /// `BodyId`, we need to handle it on its own.
@@ -2283,14 +2303,14 @@ crate struct TypeBinding {
 
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 crate enum TypeBindingKind {
-    Equality { ty: Type },
+    Equality { term: Term },
     Constraint { bounds: Vec<GenericBound> },
 }
 
 impl TypeBinding {
-    crate fn ty(&self) -> &Type {
+    crate fn term(&self) -> &Term {
         match self.kind {
-            TypeBindingKind::Equality { ref ty } => ty,
+            TypeBindingKind::Equality { ref term } => term,
             _ => panic!("expected equality type binding for parenthesized generic args"),
         }
     }
diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs
index 8571a6a137f..08840626259 100644
--- a/src/librustdoc/html/format.rs
+++ b/src/librustdoc/html/format.rs
@@ -1442,11 +1442,11 @@ impl clean::TypeBinding {
         display_fn(move |f| {
             f.write_str(self.name.as_str())?;
             match self.kind {
-                clean::TypeBindingKind::Equality { ref ty } => {
+                clean::TypeBindingKind::Equality { ref term } => {
                     if f.alternate() {
-                        write!(f, " = {:#}", ty.print(cx))?;
+                        write!(f, " = {:#}", term.print(cx))?;
                     } else {
-                        write!(f, " = {}", ty.print(cx))?;
+                        write!(f, " = {}", term.print(cx))?;
                     }
                 }
                 clean::TypeBindingKind::Constraint { ref bounds } => {
@@ -1492,6 +1492,18 @@ impl clean::GenericArg {
     }
 }
 
+impl clean::types::Term {
+    crate fn print<'a, 'tcx: 'a>(
+        &'a self,
+        cx: &'a Context<'tcx>,
+    ) -> impl fmt::Display + 'a + Captures<'tcx> {
+        match self {
+            clean::types::Term::Type(ty) => ty.print(cx),
+            _ => todo!(),
+        }
+    }
+}
+
 crate fn display_fn(f: impl FnOnce(&mut fmt::Formatter<'_>) -> fmt::Result) -> impl fmt::Display {
     struct WithFormatter<F>(Cell<Option<F>>);
 
diff --git a/src/librustdoc/json/conversions.rs b/src/librustdoc/json/conversions.rs
index c8efa4bbbcc..e77bd5c9223 100644
--- a/src/librustdoc/json/conversions.rs
+++ b/src/librustdoc/json/conversions.rs
@@ -162,7 +162,7 @@ impl FromWithTcx<clean::TypeBindingKind> for TypeBindingKind {
     fn from_tcx(kind: clean::TypeBindingKind, tcx: TyCtxt<'_>) -> Self {
         use clean::TypeBindingKind::*;
         match kind {
-            Equality { ty } => TypeBindingKind::Equality(ty.into_tcx(tcx)),
+            Equality { term } => TypeBindingKind::Equality(term.into_tcx(tcx)),
             Constraint { bounds } => {
                 TypeBindingKind::Constraint(bounds.into_iter().map(|a| a.into_tcx(tcx)).collect())
             }
@@ -452,6 +452,15 @@ impl FromWithTcx<clean::Type> for Type {
     }
 }
 
+impl FromWithTcx<clean::Term> for Term {
+    fn from_tcx(term: clean::Term, tcx: TyCtxt<'_>) -> Term {
+        match term {
+            clean::Term::Type(ty) => Term::Type(FromWithTcx::from_tcx(ty, tcx)),
+            clean::Term::Constant(c) => Term::Constant(FromWithTcx::from_tcx(c, tcx)),
+        }
+    }
+}
+
 impl FromWithTcx<clean::BareFunctionDecl> for FunctionPointer {
     fn from_tcx(bare_decl: clean::BareFunctionDecl, tcx: TyCtxt<'_>) -> Self {
         let clean::BareFunctionDecl { unsafety, generic_params, decl, abi } = bare_decl;
diff --git a/src/llvm-project b/src/llvm-project
-Subproject 2abffbf977a9e8c6ca4174a08fe5c4d7781f0aa
+Subproject 6b3dbcc81a470e5da84576d63fcfc19e3b1154c
diff --git a/src/rustdoc-json-types/lib.rs b/src/rustdoc-json-types/lib.rs
index 9466f84ffcd..618c8aab86a 100644
--- a/src/rustdoc-json-types/lib.rs
+++ b/src/rustdoc-json-types/lib.rs
@@ -148,7 +148,7 @@ pub struct TypeBinding {
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
 #[serde(rename_all = "snake_case")]
 pub enum TypeBindingKind {
-    Equality(Type),
+    Equality(Term),
     Constraint(Vec<GenericBound>),
 }
 
@@ -335,7 +335,7 @@ pub enum GenericParamDefKind {
 pub enum WherePredicate {
     BoundPredicate { ty: Type, bounds: Vec<GenericBound> },
     RegionPredicate { lifetime: String, bounds: Vec<GenericBound> },
-    EqPredicate { lhs: Type, rhs: Type },
+    EqPredicate { lhs: Type, rhs: Term },
 }
 
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
@@ -361,6 +361,13 @@ pub enum TraitBoundModifier {
 
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
 #[serde(rename_all = "snake_case")]
+pub enum Term {
+    Type(Type),
+    Constant(Constant),
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
+#[serde(rename_all = "snake_case")]
 #[serde(tag = "kind", content = "inner")]
 pub enum Type {
     /// Structs, enums, and traits
diff --git a/src/test/ui/associated-consts/assoc-const.rs b/src/test/ui/associated-consts/assoc-const.rs
new file mode 100644
index 00000000000..cd4b42f9f84
--- /dev/null
+++ b/src/test/ui/associated-consts/assoc-const.rs
@@ -0,0 +1,21 @@
+#![feature(associated_const_equality)]
+
+pub trait Foo {
+  const N: usize;
+}
+
+pub struct Bar;
+
+impl Foo for Bar {
+  const N: usize = 3;
+}
+
+const TEST:usize = 3;
+
+
+fn foo<F: Foo<N=3>>() {}
+//~^ ERROR associated const equality is incomplete
+fn bar<F: Foo<N={TEST}>>() {}
+//~^ ERROR associated const equality is incomplete
+
+fn main() {}
diff --git a/src/test/ui/associated-consts/assoc-const.stderr b/src/test/ui/associated-consts/assoc-const.stderr
new file mode 100644
index 00000000000..ccaa6fa8ee8
--- /dev/null
+++ b/src/test/ui/associated-consts/assoc-const.stderr
@@ -0,0 +1,14 @@
+error: associated const equality is incomplete
+  --> $DIR/assoc-const.rs:16:15
+   |
+LL | fn foo<F: Foo<N=3>>() {}
+   |               ^^^ cannot yet relate associated const
+
+error: associated const equality is incomplete
+  --> $DIR/assoc-const.rs:18:15
+   |
+LL | fn bar<F: Foo<N={TEST}>>() {}
+   |               ^^^^^^^^ cannot yet relate associated const
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.rs b/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.rs
index 19e0f38d320..b126b24853f 100644
--- a/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.rs
+++ b/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.rs
@@ -7,8 +7,9 @@ struct Bar;
 const T: usize = 42;
 
 impl Foo<N = 3> for Bar {
-//~^ ERROR cannot constrain an associated constant to a value
+//~^ ERROR this trait takes 1 generic argument but 0 generic arguments were supplied
 //~| ERROR associated type bindings are not allowed here
+//~| ERROR associated const equality is incomplete
     fn do_x(&self) -> [u8; 3] {
         [0u8; 3]
     }
diff --git a/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.stderr b/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.stderr
index bbca92ad63a..59ba054aa11 100644
--- a/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.stderr
+++ b/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.stderr
@@ -1,11 +1,27 @@
-error: cannot constrain an associated constant to a value
+error[E0658]: associated const equality is incomplete
   --> $DIR/issue-89013-no-kw.rs:9:10
    |
 LL | impl Foo<N = 3> for Bar {
-   |          -^^^-
-   |          |   |
-   |          |   ...cannot be constrained to this value
-   |          this associated constant...
+   |          ^^^^^
+   |
+   = note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
+   = help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
+
+error[E0107]: this trait takes 1 generic argument but 0 generic arguments were supplied
+  --> $DIR/issue-89013-no-kw.rs:9:6
+   |
+LL | impl Foo<N = 3> for Bar {
+   |      ^^^ expected 1 generic argument
+   |
+note: trait defined here, with 1 generic parameter: `N`
+  --> $DIR/issue-89013-no-kw.rs:1:7
+   |
+LL | trait Foo<const N: usize> {
+   |       ^^^       -
+help: add missing generic argument
+   |
+LL | impl Foo<N, N = 3> for Bar {
+   |          ++
 
 error[E0229]: associated type bindings are not allowed here
   --> $DIR/issue-89013-no-kw.rs:9:10
@@ -13,6 +29,7 @@ error[E0229]: associated type bindings are not allowed here
 LL | impl Foo<N = 3> for Bar {
    |          ^^^^^ associated type not allowed here
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0229`.
+Some errors have detailed explanations: E0107, E0229, E0658.
+For more information about an error, try `rustc --explain E0107`.
diff --git a/src/test/ui/const-generics/parser-error-recovery/issue-89013.rs b/src/test/ui/const-generics/parser-error-recovery/issue-89013.rs
index ca1158a2f6d..9431779faf8 100644
--- a/src/test/ui/const-generics/parser-error-recovery/issue-89013.rs
+++ b/src/test/ui/const-generics/parser-error-recovery/issue-89013.rs
@@ -8,8 +8,9 @@ const T: usize = 42;
 
 impl Foo<N = const 3> for Bar {
 //~^ ERROR expected lifetime, type, or constant, found keyword `const`
-//~| ERROR cannot constrain an associated constant to a value
+//~| ERROR this trait takes 1 generic
 //~| ERROR associated type bindings are not allowed here
+//~| ERROR associated const equality is incomplete
     fn do_x(&self) -> [u8; 3] {
         [0u8; 3]
     }
diff --git a/src/test/ui/const-generics/parser-error-recovery/issue-89013.stderr b/src/test/ui/const-generics/parser-error-recovery/issue-89013.stderr
index 85379d3f06e..9d473992670 100644
--- a/src/test/ui/const-generics/parser-error-recovery/issue-89013.stderr
+++ b/src/test/ui/const-generics/parser-error-recovery/issue-89013.stderr
@@ -10,14 +10,30 @@ LL - impl Foo<N = const 3> for Bar {
 LL + impl Foo<N = 3> for Bar {
    | 
 
-error: cannot constrain an associated constant to a value
+error[E0658]: associated const equality is incomplete
   --> $DIR/issue-89013.rs:9:10
    |
 LL | impl Foo<N = const 3> for Bar {
-   |          -^^^^^^^^^-
-   |          |         |
-   |          |         ...cannot be constrained to this value
-   |          this associated constant...
+   |          ^^^^^^^^^^^
+   |
+   = note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
+   = help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
+
+error[E0107]: this trait takes 1 generic argument but 0 generic arguments were supplied
+  --> $DIR/issue-89013.rs:9:6
+   |
+LL | impl Foo<N = const 3> for Bar {
+   |      ^^^ expected 1 generic argument
+   |
+note: trait defined here, with 1 generic parameter: `N`
+  --> $DIR/issue-89013.rs:1:7
+   |
+LL | trait Foo<const N: usize> {
+   |       ^^^       -
+help: add missing generic argument
+   |
+LL | impl Foo<N, N = const 3> for Bar {
+   |          ++
 
 error[E0229]: associated type bindings are not allowed here
   --> $DIR/issue-89013.rs:9:10
@@ -25,6 +41,7 @@ error[E0229]: associated type bindings are not allowed here
 LL | impl Foo<N = const 3> for Bar {
    |          ^^^^^^^^^^^ associated type not allowed here
 
-error: aborting due to 3 previous errors
+error: aborting due to 4 previous errors
 
-For more information about this error, try `rustc --explain E0229`.
+Some errors have detailed explanations: E0107, E0229, E0658.
+For more information about an error, try `rustc --explain E0107`.
diff --git a/src/test/ui/feature-gates/feature-gate-associated_const_equality.rs b/src/test/ui/feature-gates/feature-gate-associated_const_equality.rs
new file mode 100644
index 00000000000..b51ead2a188
--- /dev/null
+++ b/src/test/ui/feature-gates/feature-gate-associated_const_equality.rs
@@ -0,0 +1,16 @@
+pub trait TraitWAssocConst {
+  const A: usize;
+}
+pub struct Demo {}
+
+impl TraitWAssocConst for Demo {
+  const A: usize = 32;
+}
+
+fn foo<A: TraitWAssocConst<A=32>>() {}
+//~^ ERROR associated const equality
+//~| ERROR associated const equality
+
+fn main() {
+  foo::<Demo>();
+}
diff --git a/src/test/ui/feature-gates/feature-gate-associated_const_equality.stderr b/src/test/ui/feature-gates/feature-gate-associated_const_equality.stderr
new file mode 100644
index 00000000000..f4db49c4af8
--- /dev/null
+++ b/src/test/ui/feature-gates/feature-gate-associated_const_equality.stderr
@@ -0,0 +1,18 @@
+error[E0658]: associated const equality is incomplete
+  --> $DIR/feature-gate-associated_const_equality.rs:10:28
+   |
+LL | fn foo<A: TraitWAssocConst<A=32>>() {}
+   |                            ^^^^
+   |
+   = note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
+   = help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
+
+error: associated const equality is incomplete
+  --> $DIR/feature-gate-associated_const_equality.rs:10:28
+   |
+LL | fn foo<A: TraitWAssocConst<A=32>>() {}
+   |                            ^^^^ cannot yet relate associated const
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/parser/recover-assoc-const-constraint.rs b/src/test/ui/parser/recover-assoc-const-constraint.rs
index 06be3cdcc1a..1453e6cb5cd 100644
--- a/src/test/ui/parser/recover-assoc-const-constraint.rs
+++ b/src/test/ui/parser/recover-assoc-const-constraint.rs
@@ -1,7 +1,9 @@
 #[cfg(FALSE)]
 fn syntax() {
-    bar::<Item = 42>(); //~ ERROR cannot constrain an associated constant to a value
-    bar::<Item = { 42 }>(); //~ ERROR cannot constrain an associated constant to a value
+    bar::<Item = 42>();
+    //~^ ERROR associated const equality is incomplete
+    bar::<Item = { 42 }>();
+    //~^ ERROR associated const equality is incomplete
 }
 
 fn main() {}
diff --git a/src/test/ui/parser/recover-assoc-const-constraint.stderr b/src/test/ui/parser/recover-assoc-const-constraint.stderr
index c6733b33faa..2d36ce4e986 100644
--- a/src/test/ui/parser/recover-assoc-const-constraint.stderr
+++ b/src/test/ui/parser/recover-assoc-const-constraint.stderr
@@ -1,20 +1,21 @@
-error: cannot constrain an associated constant to a value
+error[E0658]: associated const equality is incomplete
   --> $DIR/recover-assoc-const-constraint.rs:3:11
    |
 LL |     bar::<Item = 42>();
-   |           ----^^^--
-   |           |      |
-   |           |      ...cannot be constrained to this value
-   |           this associated constant...
+   |           ^^^^^^^^^
+   |
+   = note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
+   = help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
 
-error: cannot constrain an associated constant to a value
-  --> $DIR/recover-assoc-const-constraint.rs:4:11
+error[E0658]: associated const equality is incomplete
+  --> $DIR/recover-assoc-const-constraint.rs:5:11
    |
 LL |     bar::<Item = { 42 }>();
-   |           ----^^^------
-   |           |      |
-   |           |      ...cannot be constrained to this value
-   |           this associated constant...
+   |           ^^^^^^^^^^^^^
+   |
+   = note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
+   = help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/specialization/min_specialization/repeated_projection_type.stderr b/src/test/ui/specialization/min_specialization/repeated_projection_type.stderr
index 07d194476a5..ad51707070f 100644
--- a/src/test/ui/specialization/min_specialization/repeated_projection_type.stderr
+++ b/src/test/ui/specialization/min_specialization/repeated_projection_type.stderr
@@ -1,4 +1,4 @@
-error: cannot specialize on `Binder(ProjectionPredicate(ProjectionTy { substs: [V], item_def_id: DefId(0:6 ~ repeated_projection_type[HASH]::Id::This) }, (I,)), [])`
+error: cannot specialize on `Binder(ProjectionPredicate(ProjectionTy { substs: [V], item_def_id: DefId(0:6 ~ repeated_projection_type[HASH]::Id::This) }, Ty((I,))), [])`
   --> $DIR/repeated_projection_type.rs:19:1
    |
 LL | / impl<I, V: Id<This = (I,)>> X for V {
diff --git a/src/tools/cargo b/src/tools/cargo
-Subproject 06b9d31743210b788b130c8a484c2838afa6fc2
+Subproject 358e79fe56fe374649275ca7aebaafd57ade0e8
diff --git a/src/tools/clippy/clippy_lints/src/manual_async_fn.rs b/src/tools/clippy/clippy_lints/src/manual_async_fn.rs
index 86819752f90..2af3555e370 100644
--- a/src/tools/clippy/clippy_lints/src/manual_async_fn.rs
+++ b/src/tools/clippy/clippy_lints/src/manual_async_fn.rs
@@ -6,7 +6,7 @@ use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::FnKind;
 use rustc_hir::{
-    AsyncGeneratorKind, Block, Body, Expr, ExprKind, FnDecl, FnRetTy, GeneratorKind, GenericArg, GenericBound, HirId,
+    Term, AsyncGeneratorKind, Block, Body, Expr, ExprKind, FnDecl, FnRetTy, GeneratorKind, GenericArg, GenericBound, HirId,
     IsAsync, ItemKind, LifetimeName, TraitRef, Ty, TyKind, TypeBindingKind,
 };
 use rustc_lint::{LateContext, LateLintPass};
@@ -140,7 +140,7 @@ fn future_output_ty<'tcx>(trait_ref: &'tcx TraitRef<'tcx>) -> Option<&'tcx Ty<'t
         if args.bindings.len() == 1;
         let binding = &args.bindings[0];
         if binding.ident.name == sym::Output;
-        if let TypeBindingKind::Equality{ty: output} = binding.kind;
+        if let TypeBindingKind::Equality{term: Term::Ty(output)} = binding.kind;
         then {
             return Some(output)
         }
diff --git a/src/tools/clippy/clippy_lints/src/methods/mod.rs b/src/tools/clippy/clippy_lints/src/methods/mod.rs
index 7357219f7b4..a9a06c3db75 100644
--- a/src/tools/clippy/clippy_lints/src/methods/mod.rs
+++ b/src/tools/clippy/clippy_lints/src/methods/mod.rs
@@ -2178,12 +2178,16 @@ impl<'tcx> LateLintPass<'tcx> for Methods {
                 // one of the associated types must be Self
                 for &(predicate, _span) in cx.tcx.explicit_item_bounds(def_id) {
                     if let ty::PredicateKind::Projection(projection_predicate) = predicate.kind().skip_binder() {
+                        let assoc_ty = match projection_predicate.term {
+                          ty::Term::Ty(ty) => ty,
+                          ty::Term::Const(_c) => continue,
+                        };
                         // walk the associated type and check for Self
                         if let Some(self_adt) = self_ty.ty_adt_def() {
-                            if contains_adt_constructor(projection_predicate.ty, self_adt) {
+                            if contains_adt_constructor(assoc_ty, self_adt) {
                                 return;
                             }
-                        } else if contains_ty(projection_predicate.ty, self_ty) {
+                        } else if contains_ty(assoc_ty, self_ty) {
                             return;
                         }
                     }
diff --git a/src/tools/clippy/clippy_lints/src/methods/unnecessary_to_owned.rs b/src/tools/clippy/clippy_lints/src/methods/unnecessary_to_owned.rs
index e5b6d296b2d..9162de3ccea 100644
--- a/src/tools/clippy/clippy_lints/src/methods/unnecessary_to_owned.rs
+++ b/src/tools/clippy/clippy_lints/src/methods/unnecessary_to_owned.rs
@@ -243,9 +243,10 @@ fn check_other_call_arg<'tcx>(
         if if trait_predicate.def_id() == deref_trait_id {
             if let [projection_predicate] = projection_predicates[..] {
                 let normalized_ty =
-                    cx.tcx.subst_and_normalize_erasing_regions(call_substs, cx.param_env, projection_predicate.ty);
+                    cx.tcx.subst_and_normalize_erasing_regions(call_substs, cx.param_env, projection_predicate.term);
                 implements_trait(cx, receiver_ty, deref_trait_id, &[])
-                    && get_associated_type(cx, receiver_ty, deref_trait_id, "Target") == Some(normalized_ty)
+                    && get_associated_type(cx, receiver_ty, deref_trait_id,
+                    "Target").map_or(false, |ty| ty::Term::Ty(ty) == normalized_ty)
             } else {
                 false
             }
diff --git a/src/tools/clippy/clippy_lints/src/unit_return_expecting_ord.rs b/src/tools/clippy/clippy_lints/src/unit_return_expecting_ord.rs
index fe35ff33d35..68156df2ece 100644
--- a/src/tools/clippy/clippy_lints/src/unit_return_expecting_ord.rs
+++ b/src/tools/clippy/clippy_lints/src/unit_return_expecting_ord.rs
@@ -98,9 +98,10 @@ fn get_args_to_check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> Ve
                         if trait_pred.self_ty() == inp;
                         if let Some(return_ty_pred) = get_projection_pred(cx, generics, *trait_pred);
                         then {
-                            if ord_preds.iter().any(|ord| ord.self_ty() == return_ty_pred.ty) {
+                            if ord_preds.iter().any(|ord| Some(ord.self_ty()) ==
+                            return_ty_pred.term.ty()) {
                                 args_to_check.push((i, "Ord".to_string()));
-                            } else if partial_ord_preds.iter().any(|pord| pord.self_ty() == return_ty_pred.ty) {
+                            } else if partial_ord_preds.iter().any(|pord| pord.self_ty() == return_ty_pred.term.ty().unwrap()) {
                                 args_to_check.push((i, "PartialOrd".to_string()));
                             }
                         }
diff --git a/src/tools/clippy/clippy_utils/src/ast_utils.rs b/src/tools/clippy/clippy_utils/src/ast_utils.rs
index 3d3180521ab..604c95d2bc8 100644
--- a/src/tools/clippy/clippy_utils/src/ast_utils.rs
+++ b/src/tools/clippy/clippy_utils/src/ast_utils.rs
@@ -645,11 +645,19 @@ pub fn eq_generic_bound(l: &GenericBound, r: &GenericBound) -> bool {
     }
 }
 
-pub fn eq_assoc_constraint(l: &AssocTyConstraint, r: &AssocTyConstraint) -> bool {
-    use AssocTyConstraintKind::*;
+fn eq_term(l: &Term, r: &Term) -> bool {
+  match (l, r) {
+    (Term::Ty(l), Term::Ty(r)) => eq_ty(l,r),
+    (Term::Const(l), Term::Const(r)) => eq_anon_const(l,r),
+    _ => false,
+  }
+}
+
+pub fn eq_assoc_constraint(l: &AssocConstraint, r: &AssocConstraint) -> bool {
+    use AssocConstraintKind::*;
     eq_id(l.ident, r.ident)
         && match (&l.kind, &r.kind) {
-            (Equality { ty: l }, Equality { ty: r }) => eq_ty(l, r),
+            (Equality { term: l }, Equality { term: r }) => eq_term(l, r),
             (Bound { bounds: l }, Bound { bounds: r }) => over(l, r, eq_generic_bound),
             _ => false,
         }
diff --git a/src/tools/rust-analyzer b/src/tools/rust-analyzer
-Subproject 0f8c96c92689af8378dbe9f466c6bf15a3a2745
+Subproject 8e9ccbf97a70259b6c6576e8fd7d77d28238737
diff --git a/src/tools/rustfmt/src/types.rs b/src/tools/rustfmt/src/types.rs
index 88f5dc43245..5de30129266 100644
--- a/src/tools/rustfmt/src/types.rs
+++ b/src/tools/rustfmt/src/types.rs
@@ -1,7 +1,7 @@
 use std::iter::ExactSizeIterator;
 use std::ops::Deref;
 
-use rustc_ast::ast::{self, FnRetTy, Mutability};
+use rustc_ast::ast::{self, FnRetTy, Mutability, Term};
 use rustc_ast::ptr;
 use rustc_span::{symbol::kw, BytePos, Pos, Span};
 
@@ -141,7 +141,7 @@ pub(crate) enum SegmentParam<'a> {
     Const(&'a ast::AnonConst),
     LifeTime(&'a ast::Lifetime),
     Type(&'a ast::Ty),
-    Binding(&'a ast::AssocTyConstraint),
+    Binding(&'a ast::AssocConstraint),
 }
 
 impl<'a> SegmentParam<'a> {
@@ -176,9 +176,9 @@ impl<'a> Rewrite for SegmentParam<'a> {
     }
 }
 
-impl Rewrite for ast::AssocTyConstraint {
+impl Rewrite for ast::AssocConstraint {
     fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
-        use ast::AssocTyConstraintKind::{Bound, Equality};
+        use ast::AssocConstraintKind::{Bound, Equality};
 
         let mut result = String::with_capacity(128);
         result.push_str(rewrite_ident(context, self.ident));
@@ -206,11 +206,14 @@ impl Rewrite for ast::AssocTyConstraint {
     }
 }
 
-impl Rewrite for ast::AssocTyConstraintKind {
+impl Rewrite for ast::AssocConstraintKind {
     fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
         match self {
-            ast::AssocTyConstraintKind::Equality { ty } => ty.rewrite(context, shape),
-            ast::AssocTyConstraintKind::Bound { bounds } => bounds.rewrite(context, shape),
+            ast::AssocConstraintKind::Equality { term } => match term {
+                Term::Ty(ty) => ty.rewrite(context, shape),
+                Term::Const(c) => c.rewrite(context, shape),
+            },
+            ast::AssocConstraintKind::Bound { bounds } => bounds.rewrite(context, shape),
         }
     }
 }