canonicalization

compiler/rustc_infer/src/infer/at.rs

@@ -369,6 +369,34 @@ impl<'tcx> ToTrace<'tcx> for Const<'tcx> {
     }
 }
 
+impl<'tcx> ToTrace<'tcx> for ty::GenericArg<'tcx> {
+    fn to_trace(
+        _: TyCtxt<'tcx>,
+        cause: &ObligationCause<'tcx>,
+        a_is_expected: bool,
+        a: Self,
+        b: Self,
+    ) -> TypeTrace<'tcx> {
+        use GenericArgKind::*;
+        TypeTrace {
+            cause: cause.clone(),
+            values: match (a.unpack(), b.unpack()) {
+                (Lifetime(a), Lifetime(b)) => Regions(ExpectedFound::new(a_is_expected, a, b)),
+                (Type(a), Type(b)) => Terms(ExpectedFound::new(a_is_expected, a.into(), b.into())),
+                (Const(a), Const(b)) => {
+                    Terms(ExpectedFound::new(a_is_expected, a.into(), b.into()))
+                }
+
+                (Lifetime(_), Type(_) | Const(_))
+                | (Type(_), Lifetime(_) | Const(_))
+                | (Const(_), Lifetime(_) | Type(_)) => {
+                    bug!("relating different kinds: {a:?} {b:?}")
+                }
+            },
+        }
+    }
+}
+
 impl<'tcx> ToTrace<'tcx> for ty::Term<'tcx> {
     fn to_trace(
         _: TyCtxt<'tcx>,

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

@@ -30,7 +30,7 @@ use rustc_middle::ty::{self, List, TyCtxt};
 use rustc_span::source_map::Span;
 
 pub use rustc_middle::infer::canonical::*;
-use substitute::CanonicalExt;
+pub use substitute::CanonicalExt;
 
 mod canonicalizer;
 pub mod query_response;
@@ -100,7 +100,11 @@ impl<'tcx> InferCtxt<'tcx> {
     /// variable for it. If this is an existentially quantified
     /// variable, then you'll get a new inference variable; if it is a
     /// universally quantified variable, you get a placeholder.
-    fn instantiate_canonical_var(
+    ///
+    /// FIXME(-Ztrait-solver=next): This is public because it's used by the
+    /// new trait solver which has a different canonicalization routine.
+    /// We should somehow deduplicate all of this.
+    pub fn instantiate_canonical_var(
         &self,
         span: Span,
         cv_info: CanonicalVarInfo<'tcx>,

compiler/rustc_infer/src/infer/canonical/query_response.rs

@@ -151,11 +151,21 @@ impl<'tcx> InferCtxt<'tcx> {
         })
     }
 
-    /// FIXME: This method should only be used for canonical queries and therefore be private.
-    ///
-    /// As the new solver does canonicalization slightly differently, this is also used there
-    /// for now. This should hopefully change fairly soon.
-    pub fn take_opaque_types_for_query_response(&self) -> Vec<(Ty<'tcx>, Ty<'tcx>)> {
+    /// Used by the new solver as that one takes the opaque types at the end of a probe
+    /// to deal with multiple candidates without having to recompute them.
+    pub fn clone_opaque_types_for_query_response(&self) -> Vec<(Ty<'tcx>, Ty<'tcx>)> {
+        self.inner
+            .borrow()
+            .opaque_type_storage
+            .opaque_types
+            .iter()
+            .map(|&(k, ref v)| {
+                (self.tcx.mk_opaque(k.def_id.to_def_id(), k.substs), v.hidden_type.ty)
+            })
+            .collect()
+    }
+
+    fn take_opaque_types_for_query_response(&self) -> Vec<(Ty<'tcx>, Ty<'tcx>)> {
         std::mem::take(&mut self.inner.borrow_mut().opaque_type_storage.opaque_types)
             .into_iter()
             .map(|(k, v)| (self.tcx.mk_opaque(k.def_id.to_def_id(), k.substs), v.hidden_type.ty))

compiler/rustc_infer/src/infer/canonical/substitute.rs

@@ -11,7 +11,9 @@ use rustc_middle::ty::fold::{FnMutDelegate, TypeFoldable};
 use rustc_middle::ty::subst::GenericArgKind;
 use rustc_middle::ty::{self, TyCtxt};
 
-pub(super) trait CanonicalExt<'tcx, V> {
+/// FIXME(-Ztrait-solver=next): This or public because it is shared with the
+/// new trait solver implementation. We should deduplicate canonicalization.
+pub trait CanonicalExt<'tcx, V> {
     /// Instantiate the wrapped value, replacing each canonical value
     /// with the value given in `var_values`.
     fn substitute(&self, tcx: TyCtxt<'tcx>, var_values: &CanonicalVarValues<'tcx>) -> V