2 files changed, 24 insertions, 6 deletions
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
index 7318d02d24c..61898b06476 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
@@ -1388,10 +1388,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // This also occurs for an enum variant on a type alias.
             let impl_ty = self.normalize(span, tcx.type_of(impl_def_id).instantiate(tcx, args));
             let self_ty = self.normalize(span, self_ty);
-            match self.at(&self.misc(span), self.param_env).sub(
+            match self.at(&self.misc(span), self.param_env).eq(
                 DefineOpaqueTypes::Yes,
-                self_ty,
                 impl_ty,
+                self_ty,
             ) {
                 Ok(ok) => self.register_infer_ok_obligations(ok),
                 Err(_) => {
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
index 5dc341653e5..17aa43ae7c0 100644
--- a/compiler/rustc_hir_typeck/src/method/probe.rs
+++ b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -621,6 +621,16 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         self.unsatisfied_predicates.borrow_mut().clear();
     }
 
+    /// When we're looking up a method by path (UFCS), we relate the receiver
+    /// types invariantly. When we are looking up a method by the `.` operator,
+    /// we relate them covariantly.
+    fn variance(&self) -> ty::Variance {
+        match self.mode {
+            Mode::MethodCall => ty::Covariant,
+            Mode::Path => ty::Invariant,
+        }
+    }
+
     ///////////////////////////////////////////////////////////////////////////
     // CANDIDATE ASSEMBLY
 
@@ -1443,7 +1453,8 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                     (xform_self_ty, xform_ret_ty) =
                         self.xform_self_ty(probe.item, impl_ty, impl_args);
                     xform_self_ty = ocx.normalize(cause, self.param_env, xform_self_ty);
-                    match ocx.sup(cause, self.param_env, xform_self_ty, self_ty) {
+                    match ocx.relate(cause, self.param_env, self.variance(), self_ty, xform_self_ty)
+                    {
                         Ok(()) => {}
                         Err(err) => {
                             debug!("--> cannot relate self-types {:?}", err);
@@ -1514,7 +1525,13 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                         {
                             return ProbeResult::NoMatch;
                         }
-                        _ => match ocx.sup(cause, self.param_env, xform_self_ty, self_ty) {
+                        _ => match ocx.relate(
+                            cause,
+                            self.param_env,
+                            self.variance(),
+                            self_ty,
+                            xform_self_ty,
+                        ) {
                             Ok(()) => {}
                             Err(err) => {
                                 debug!("--> cannot relate self-types {:?}", err);
@@ -1560,7 +1577,8 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                     (xform_self_ty, xform_ret_ty) =
                         self.xform_self_ty(probe.item, trait_ref.self_ty(), trait_ref.args);
                     xform_self_ty = ocx.normalize(cause, self.param_env, xform_self_ty);
-                    match ocx.sup(cause, self.param_env, xform_self_ty, self_ty) {
+                    match ocx.relate(cause, self.param_env, self.variance(), self_ty, xform_self_ty)
+                    {
                         Ok(()) => {}
                         Err(err) => {
                             debug!("--> cannot relate self-types {:?}", err);
@@ -1603,7 +1621,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                 }
 
                 debug!("comparing return_ty {:?} with xform ret ty {:?}", return_ty, xform_ret_ty);
-                match ocx.sup(cause, self.param_env, return_ty, xform_ret_ty) {
+                match ocx.relate(cause, self.param_env, self.variance(), xform_ret_ty, return_ty) {
                     Ok(()) => {}
                     Err(_) => {
                         result = ProbeResult::BadReturnType;