hir: resolve associated items in docs (excl. type aliases)

crates/hir/src/lib.rs

@@ -4121,6 +4121,10 @@ impl Type {
         }
     }
 
+    pub(crate) fn canonical(&self) -> Canonical<Ty> {
+        hir_ty::replace_errors_with_variables(&self.ty)
+    }
+
     /// Returns types that this type dereferences to (including this type itself). The returned
     /// iterator won't yield the same type more than once even if the deref chain contains a cycle.
     pub fn autoderef(&self, db: &dyn HirDatabase) -> impl Iterator<Item = Type> + '_ {