1 files changed, 10 insertions, 18 deletions
diff --git a/compiler/rustc_hir_typeck/src/method/prelude2021.rs b/compiler/rustc_hir_typeck/src/method/prelude2021.rs
index 3c98a2aa3..dea14dd93 100644
--- a/compiler/rustc_hir_typeck/src/method/prelude2021.rs
+++ b/compiler/rustc_hir_typeck/src/method/prelude2021.rs
@@ -5,10 +5,9 @@ use crate::{
 use hir::def_id::DefId;
 use hir::HirId;
 use hir::ItemKind;
-use rustc_ast::Mutability;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
-use rustc_middle::ty::subst::InternalSubsts;
+use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_middle::ty::{Adt, Array, Ref, Ty};
 use rustc_session::lint::builtin::RUST_2021_PRELUDE_COLLISIONS;
 use rustc_span::symbol::kw::{Empty, Underscore};
@@ -88,14 +87,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     let derefs = "*".repeat(pick.autoderefs);
 
                     let autoref = match pick.autoref_or_ptr_adjustment {
-                        Some(probe::AutorefOrPtrAdjustment::Autoref {
-                            mutbl: Mutability::Mut,
-                            ..
-                        }) => "&mut ",
-                        Some(probe::AutorefOrPtrAdjustment::Autoref {
-                            mutbl: Mutability::Not,
-                            ..
-                        }) => "&",
+                        Some(probe::AutorefOrPtrAdjustment::Autoref { mutbl, .. }) => {
+                            mutbl.ref_prefix_str()
+                        }
                         Some(probe::AutorefOrPtrAdjustment::ToConstPtr) | None => "",
                     };
                     if let Ok(self_expr) = self.sess().source_map().span_to_snippet(self_expr.span)
@@ -227,14 +221,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // If we know it does not, we don't need to warn.
         if method_name.name == sym::from_iter {
             if let Some(trait_def_id) = self.tcx.get_diagnostic_item(sym::FromIterator) {
+                let any_type = self.infcx.next_ty_var(TypeVariableOrigin {
+                    kind: TypeVariableOriginKind::MiscVariable,
+                    span,
+                });
                 if !self
                     .infcx
-                    .type_implements_trait(
-                        trait_def_id,
-                        self_ty,
-                        InternalSubsts::empty(),
-                        self.param_env,
-                    )
+                    .type_implements_trait(trait_def_id, [self_ty, any_type], self.param_env)
                     .may_apply()
                 {
                     return;
@@ -387,8 +380,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let derefs = "*".repeat(pick.autoderefs);
 
         let autoref = match pick.autoref_or_ptr_adjustment {
-            Some(probe::AutorefOrPtrAdjustment::Autoref { mutbl: Mutability::Mut, .. }) => "&mut ",
-            Some(probe::AutorefOrPtrAdjustment::Autoref { mutbl: Mutability::Not, .. }) => "&",
+            Some(probe::AutorefOrPtrAdjustment::Autoref { mutbl, .. }) => mutbl.ref_prefix_str(),
             Some(probe::AutorefOrPtrAdjustment::ToConstPtr) | None => "",
         };