Rollup merge of #117008 - compiler-errors:canonical, r=lcnr

Uplift `Canonical` to `rustc_type_ir`

I plan on moving the new trait solver's canonicalizer into either `rustc_type_ir` or a child crate. One dependency on this is lifting `Canonical<V>` to `rustc_type_ir` so we can actually name the canonicalized values.

I may also later lift `CanonicalVarInfo` into the new trait solver. I can't really tell what other changes need to be done, but I'm just putting this up sooner than later since I'm almost certain it'll need to be done regardless of other design choices.

There are a couple of warts introduced by this PR, since we no longer can define inherent `Canonical` impls in `rustc_middle` -- see the changes to:
* `compiler/rustc_trait_selection/src/traits/query/normalize.rs`
* `compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs`

r? lcnr

4 files changed, 23 insertions, 19 deletions

diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 6a9a8bcdc06..a669ff8d961 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -6,7 +6,7 @@ pub mod tls;
 
 use crate::arena::Arena;
 use crate::dep_graph::{DepGraph, DepKindStruct};
-use crate::infer::canonical::CanonicalVarInfo;
+use crate::infer::canonical::{CanonicalVarInfo, CanonicalVarInfos};
 use crate::lint::struct_lint_level;
 use crate::metadata::ModChild;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
@@ -88,6 +88,7 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
 
     type Binder<T> = Binder<'tcx, T>;
     type TypeAndMut = TypeAndMut<'tcx>;
+    type CanonicalVars = CanonicalVarInfos<'tcx>;
 
     type Ty = Ty<'tcx>;
     type Tys = &'tcx List<Ty<'tcx>>;
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index cc0db39ac57..5d6d46e16b7 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -106,8 +106,8 @@ pub use self::sty::{
 };
 pub use self::trait_def::TraitDef;
 pub use self::typeck_results::{
-    CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, TypeckResults,
-    UserType, UserTypeAnnotationIndex,
+    CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, IsIdentity,
+    TypeckResults, UserType, UserTypeAnnotationIndex,
 };
 
 pub mod _match;
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 7f86acd4bf5..6af68bc5dba 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -449,7 +449,6 @@ TrivialTypeTraversalImpls! {
     crate::ty::IntVarValue,
     crate::ty::adjustment::PointerCoercion,
     crate::ty::RegionVid,
-    crate::ty::UniverseIndex,
     crate::ty::Variance,
     ::rustc_span::Span,
     ::rustc_span::symbol::Ident,
diff --git a/compiler/rustc_middle/src/ty/typeck_results.rs b/compiler/rustc_middle/src/ty/typeck_results.rs
index 7d516410b20..58ad1eb900f 100644
--- a/compiler/rustc_middle/src/ty/typeck_results.rs
+++ b/compiler/rustc_middle/src/ty/typeck_results.rs
@@ -594,10 +594,27 @@ pub struct CanonicalUserTypeAnnotation<'tcx> {
 /// Canonical user type annotation.
 pub type CanonicalUserType<'tcx> = Canonical<'tcx, UserType<'tcx>>;
 
-impl<'tcx> CanonicalUserType<'tcx> {
+/// A user-given type annotation attached to a constant. These arise
+/// from constants that are named via paths, like `Foo::<A>::new` and
+/// so forth.
+#[derive(Copy, Clone, Debug, PartialEq, TyEncodable, TyDecodable)]
+#[derive(Eq, Hash, HashStable, TypeFoldable, TypeVisitable)]
+pub enum UserType<'tcx> {
+    Ty(Ty<'tcx>),
+
+    /// The canonical type is the result of `type_of(def_id)` with the
+    /// given substitutions applied.
+    TypeOf(DefId, UserArgs<'tcx>),
+}
+
+pub trait IsIdentity {
+    fn is_identity(&self) -> bool;
+}
+
+impl<'tcx> IsIdentity for CanonicalUserType<'tcx> {
     /// Returns `true` if this represents a substitution of the form `[?0, ?1, ?2]`,
     /// i.e., each thing is mapped to a canonical variable with the same index.
-    pub fn is_identity(&self) -> bool {
+    fn is_identity(&self) -> bool {
         match self.value {
             UserType::Ty(_) => false,
             UserType::TypeOf(_, user_args) => {
@@ -640,19 +657,6 @@ impl<'tcx> CanonicalUserType<'tcx> {
     }
 }
 
-/// A user-given type annotation attached to a constant. These arise
-/// from constants that are named via paths, like `Foo::<A>::new` and
-/// so forth.
-#[derive(Copy, Clone, Debug, PartialEq, TyEncodable, TyDecodable)]
-#[derive(Eq, Hash, HashStable, TypeFoldable, TypeVisitable)]
-pub enum UserType<'tcx> {
-    Ty(Ty<'tcx>),
-
-    /// The canonical type is the result of `type_of(def_id)` with the
-    /// given substitutions applied.
-    TypeOf(DefId, UserArgs<'tcx>),
-}
-
 impl<'tcx> std::fmt::Display for UserType<'tcx> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {