diff --git a/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart b/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart
index 90d2f7b..3cc531a 100644
--- a/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart
@@ -4787,11 +4787,13 @@
             !isThisReceiver) {
           Member interfaceMember = readTarget.member!;
           if (interfaceMember is Procedure) {
+            DartType typeToCheck = inferrer.isNonNullableByDefault
+                ? interfaceMember.function
+                    .computeFunctionType(inferrer.library.nonNullable)
+                : interfaceMember.function.returnType;
             checkReturn =
                 TypeInferrerImpl.returnedTypeParametersOccurNonCovariantly(
-                    interfaceMember.enclosingClass!,
-                    interfaceMember.function
-                        .computeFunctionType(inferrer.library.nonNullable));
+                    interfaceMember.enclosingClass!, typeToCheck);
           } else if (interfaceMember is Field) {
             checkReturn =
                 TypeInferrerImpl.returnedTypeParametersOccurNonCovariantly(
diff --git a/pkg/front_end/testcases/general/bug33298.dart.weak.expect b/pkg/front_end/testcases/general/bug33298.dart.weak.expect
index bac28d2..397db9f 100644
--- a/pkg/front_end/testcases/general/bug33298.dart.weak.expect
+++ b/pkg/front_end/testcases/general/bug33298.dart.weak.expect
@@ -65,7 +65,7 @@
   core::List<core::String*>* list1 = <core::String*>["a", "b", "c"].{core::Iterable::map}<core::String*>(a.{self::A::call}{(core::String*) →* core::String*}){((core::String*) →* core::String*) →* core::Iterable<core::String*>*}.{core::Iterable::toList}(){({growable: core::bool*}) →* core::List<core::String*>*};
   core::List<core::String*>* list2 = <core::String*>["a", "b", "c"].{core::Iterable::map}<core::String*>(let final self::A* #t1 = a in #t1 == null ?{(core::String*) →* core::String*} null : #t1.{self::A::call}{(core::String*) →* core::String*}){((core::String*) →* core::String*) →* core::Iterable<core::String*>*}.{core::Iterable::toList}(){({growable: core::bool*}) →* core::List<core::String*>*};
   self::B<core::String*>* b = new self::B::•<core::String*>();
-  core::List<core::String*>* list3 = <core::String*>["a", "b", "c"].{core::Iterable::map}<core::String*>(b.{self::B::call}{(core::String*) →* core::String*} as{TypeError,CovarianceCheck} (core::String*) →* core::String*){((core::String*) →* core::String*) →* core::Iterable<core::String*>*}.{core::Iterable::toList}(){({growable: core::bool*}) →* core::List<core::String*>*};
+  core::List<core::String*>* list3 = <core::String*>["a", "b", "c"].{core::Iterable::map}<core::String*>(b.{self::B::call}{(core::String*) →* core::String*}){((core::String*) →* core::String*) →* core::Iterable<core::String*>*}.{core::Iterable::toList}(){({growable: core::bool*}) →* core::List<core::String*>*};
   core::List<core::String*>* list4 = <core::String*>["a", "b", "c"].{core::Iterable::map}<core::String*>(let final self::B<core::String*>* #t2 = b in #t2 == null ?{(core::String*) →* core::String*} null : #t2.{self::B::call}{(core::String*) →* core::String*}){((core::String*) →* core::String*) →* core::Iterable<core::String*>*}.{core::Iterable::toList}(){({growable: core::bool*}) →* core::List<core::String*>*};
   self::C* c = new self::C::•();
   core::List<core::String*>* list5 = <core::String*>["a", "b", "c"].{core::Iterable::map}<core::String*>(c.{self::C::call}{<T extends core::Object* = dynamic>(T*) →* T*}<core::String*>){((core::String*) →* core::String*) →* core::Iterable<core::String*>*}.{core::Iterable::toList}(){({growable: core::bool*}) →* core::List<core::String*>*};
diff --git a/pkg/front_end/testcases/general/bug33298.dart.weak.transformed.expect b/pkg/front_end/testcases/general/bug33298.dart.weak.transformed.expect
index 2fa1eb2..8f7030e 100644
--- a/pkg/front_end/testcases/general/bug33298.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general/bug33298.dart.weak.transformed.expect
@@ -65,7 +65,7 @@
   core::List<core::String*>* list1 = core::_GrowableList::_literal3<core::String*>("a", "b", "c").{core::Iterable::map}<core::String*>(a.{self::A::call}{(core::String*) →* core::String*}){((core::String*) →* core::String*) →* core::Iterable<core::String*>*}.{core::Iterable::toList}(){({growable: core::bool*}) →* core::List<core::String*>*};
   core::List<core::String*>* list2 = core::_GrowableList::_literal3<core::String*>("a", "b", "c").{core::Iterable::map}<core::String*>(let final self::A* #t1 = a in #t1 == null ?{(core::String*) →* core::String*} null : #t1.{self::A::call}{(core::String*) →* core::String*}){((core::String*) →* core::String*) →* core::Iterable<core::String*>*}.{core::Iterable::toList}(){({growable: core::bool*}) →* core::List<core::String*>*};
   self::B<core::String*>* b = new self::B::•<core::String*>();
-  core::List<core::String*>* list3 = core::_GrowableList::_literal3<core::String*>("a", "b", "c").{core::Iterable::map}<core::String*>(b.{self::B::call}{(core::String*) →* core::String*} as{TypeError,CovarianceCheck} (core::String*) →* core::String*){((core::String*) →* core::String*) →* core::Iterable<core::String*>*}.{core::Iterable::toList}(){({growable: core::bool*}) →* core::List<core::String*>*};
+  core::List<core::String*>* list3 = core::_GrowableList::_literal3<core::String*>("a", "b", "c").{core::Iterable::map}<core::String*>(b.{self::B::call}{(core::String*) →* core::String*}){((core::String*) →* core::String*) →* core::Iterable<core::String*>*}.{core::Iterable::toList}(){({growable: core::bool*}) →* core::List<core::String*>*};
   core::List<core::String*>* list4 = core::_GrowableList::_literal3<core::String*>("a", "b", "c").{core::Iterable::map}<core::String*>(let final self::B<core::String*>* #t2 = b in #t2 == null ?{(core::String*) →* core::String*} null : #t2.{self::B::call}{(core::String*) →* core::String*}){((core::String*) →* core::String*) →* core::Iterable<core::String*>*}.{core::Iterable::toList}(){({growable: core::bool*}) →* core::List<core::String*>*};
   self::C* c = new self::C::•();
   core::List<core::String*>* list5 = core::_GrowableList::_literal3<core::String*>("a", "b", "c").{core::Iterable::map}<core::String*>(c.{self::C::call}{<T extends core::Object* = dynamic>(T*) →* T*}<core::String*>){((core::String*) →* core::String*) →* core::Iterable<core::String*>*}.{core::Iterable::toList}(){({growable: core::bool*}) →* core::List<core::String*>*};
diff --git a/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart b/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart
new file mode 100644
index 0000000..60aebf5
--- /dev/null
+++ b/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart
@@ -0,0 +1,26 @@
+// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// @dart=2.6
+
+class A<X extends num> {
+  void f<Y extends X>(Y y) {}
+}
+
+expectThrows(void Function() f) {
+  try {
+    f();
+  } catch (e) {
+    return;
+  }
+  throw "Expected an exception to be thrown!";
+}
+
+main() {
+  A<num> a = new A<int>();
+  void Function<Y extends num>(Y) f = a.f;
+  expectThrows(() {
+    f(3.14);
+  });
+}
diff --git a/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.textual_outline.expect b/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.textual_outline.expect
new file mode 100644
index 0000000..29b47f8
--- /dev/null
+++ b/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.textual_outline.expect
@@ -0,0 +1,7 @@
+// @dart = 2.6
+class A<X extends num> {
+  void f<Y extends X>(Y y) {}
+}
+
+expectThrows(void Function() f) {}
+main() {}
diff --git a/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.textual_outline_modelled.expect b/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.textual_outline_modelled.expect
new file mode 100644
index 0000000..29b47f8
--- /dev/null
+++ b/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.textual_outline_modelled.expect
@@ -0,0 +1,7 @@
+// @dart = 2.6
+class A<X extends num> {
+  void f<Y extends X>(Y y) {}
+}
+
+expectThrows(void Function() f) {}
+main() {}
diff --git a/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.weak.expect b/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.weak.expect
new file mode 100644
index 0000000..9be07d6
--- /dev/null
+++ b/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.weak.expect
@@ -0,0 +1,36 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class A<X extends core::num*> extends core::Object {
+  synthetic constructor •() → self::A<self::A::X*>*
+    : super core::Object::•()
+    ;
+  method f<generic-covariant-impl Y extends self::A::X*>(self::A::f::Y* y) → void {}
+  abstract member-signature get _identityHashCode() → core::int*; -> core::Object::_identityHashCode
+  abstract member-signature method _instanceOf(dynamic instantiatorTypeArguments, dynamic functionTypeArguments, dynamic type) → core::bool*; -> core::Object::_instanceOf
+  abstract member-signature method _simpleInstanceOf(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOf
+  abstract member-signature method _simpleInstanceOfTrue(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOfTrue
+  abstract member-signature method _simpleInstanceOfFalse(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOfFalse
+  abstract member-signature operator ==(dynamic other) → core::bool*; -> core::Object::==
+  abstract member-signature get hashCode() → core::int*; -> core::Object::hashCode
+  abstract member-signature method toString() → core::String*; -> core::Object::toString
+  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
+  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
+}
+static method expectThrows(() →* void f) → dynamic {
+  try {
+    f(){() →* void};
+  }
+  on dynamic catch(final dynamic e) {
+    return;
+  }
+  throw "Expected an exception to be thrown!";
+}
+static method main() → dynamic {
+  self::A<core::num*>* a = new self::A::•<core::int*>();
+  <Y extends core::num*>(Y*) →* void f = a.{self::A::f}{<generic-covariant-impl Y extends core::num*>(Y*) →* void};
+  self::expectThrows(() → Null {
+    f<core::double*>(3.14){(core::double*) →* void};
+  });
+}
diff --git a/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.weak.outline.expect b/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.weak.outline.expect
new file mode 100644
index 0000000..50b76a4
--- /dev/null
+++ b/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.weak.outline.expect
@@ -0,0 +1,24 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class A<X extends core::num*> extends core::Object {
+  synthetic constructor •() → self::A<self::A::X*>*
+    ;
+  method f<generic-covariant-impl Y extends self::A::X*>(self::A::f::Y* y) → void
+    ;
+  abstract member-signature get _identityHashCode() → core::int*; -> core::Object::_identityHashCode
+  abstract member-signature method _instanceOf(dynamic instantiatorTypeArguments, dynamic functionTypeArguments, dynamic type) → core::bool*; -> core::Object::_instanceOf
+  abstract member-signature method _simpleInstanceOf(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOf
+  abstract member-signature method _simpleInstanceOfTrue(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOfTrue
+  abstract member-signature method _simpleInstanceOfFalse(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOfFalse
+  abstract member-signature operator ==(dynamic other) → core::bool*; -> core::Object::==
+  abstract member-signature get hashCode() → core::int*; -> core::Object::hashCode
+  abstract member-signature method toString() → core::String*; -> core::Object::toString
+  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
+  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
+}
+static method expectThrows(() →* void f) → dynamic
+  ;
+static method main() → dynamic
+  ;
diff --git a/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.weak.transformed.expect b/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.weak.transformed.expect
new file mode 100644
index 0000000..9be07d6
--- /dev/null
+++ b/pkg/front_end/testcases/general/method_tearoff_covariant_generic_type_check_opt_out.dart.weak.transformed.expect
@@ -0,0 +1,36 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+class A<X extends core::num*> extends core::Object {
+  synthetic constructor •() → self::A<self::A::X*>*
+    : super core::Object::•()
+    ;
+  method f<generic-covariant-impl Y extends self::A::X*>(self::A::f::Y* y) → void {}
+  abstract member-signature get _identityHashCode() → core::int*; -> core::Object::_identityHashCode
+  abstract member-signature method _instanceOf(dynamic instantiatorTypeArguments, dynamic functionTypeArguments, dynamic type) → core::bool*; -> core::Object::_instanceOf
+  abstract member-signature method _simpleInstanceOf(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOf
+  abstract member-signature method _simpleInstanceOfTrue(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOfTrue
+  abstract member-signature method _simpleInstanceOfFalse(dynamic type) → core::bool*; -> core::Object::_simpleInstanceOfFalse
+  abstract member-signature operator ==(dynamic other) → core::bool*; -> core::Object::==
+  abstract member-signature get hashCode() → core::int*; -> core::Object::hashCode
+  abstract member-signature method toString() → core::String*; -> core::Object::toString
+  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
+  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
+}
+static method expectThrows(() →* void f) → dynamic {
+  try {
+    f(){() →* void};
+  }
+  on dynamic catch(final dynamic e) {
+    return;
+  }
+  throw "Expected an exception to be thrown!";
+}
+static method main() → dynamic {
+  self::A<core::num*>* a = new self::A::•<core::int*>();
+  <Y extends core::num*>(Y*) →* void f = a.{self::A::f}{<generic-covariant-impl Y extends core::num*>(Y*) →* void};
+  self::expectThrows(() → Null {
+    f<core::double*>(3.14){(core::double*) →* void};
+  });
+}
diff --git a/pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_tear_off.dart b/pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_tear_off.dart
index 11693a1..0d4dd96 100644
--- a/pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_tear_off.dart
+++ b/pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_tear_off.dart
@@ -15,7 +15,7 @@
 }
 
 F<num> g1(C<num> c) {
-  return c. /*@ checkReturn=(num*) ->* void*/ f1;
+  return c.f1;
 }
 
 void g2(C<int> c, Object x) {
@@ -24,7 +24,7 @@
 }
 
 G<List<num>, num> g3(C<num> c) {
-  return c. /*@ checkReturn=(List<num*>*) ->* num**/ f2;
+  return c.f2;
 }
 
 void test() {
diff --git a/pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_tear_off.dart.weak.expect b/pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_tear_off.dart.weak.expect
index 5d38dc5..05ac14b 100644
--- a/pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_tear_off.dart.weak.expect
+++ b/pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_tear_off.dart.weak.expect
@@ -23,14 +23,14 @@
   abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
 static method g1(self::C<core::num*>* c) → (core::num*) →* void {
-  return c.{self::C::f1}{(core::num*) →* void} as{TypeError,CovarianceCheck} (core::num*) →* void;
+  return c.{self::C::f1}{(core::num*) →* void};
 }
 static method g2(self::C<core::int*>* c, core::Object* x) → void {
   (core::Object*) →* void f = self::g1(c) as (core::Object*) →* void;
   f(x){(core::Object*) →* void};
 }
 static method g3(self::C<core::num*>* c) → (core::List<core::num*>*) →* core::num* {
-  return c.{self::C::f2}{(core::List<core::num*>*) →* core::num*} as{TypeError,CovarianceCheck} (core::List<core::num*>*) →* core::num*;
+  return c.{self::C::f2}{(core::List<core::num*>*) →* core::num*};
 }
 static method test() → void {
   (core::num*) →* void x = self::g1(new self::C::•<core::int*>());
diff --git a/pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_tear_off.dart.weak.transformed.expect b/pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_tear_off.dart.weak.transformed.expect
index 5d38dc5..05ac14b 100644
--- a/pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_tear_off.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/runtime_checks/covariant_generic_parameter_tear_off.dart.weak.transformed.expect
@@ -23,14 +23,14 @@
   abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
 static method g1(self::C<core::num*>* c) → (core::num*) →* void {
-  return c.{self::C::f1}{(core::num*) →* void} as{TypeError,CovarianceCheck} (core::num*) →* void;
+  return c.{self::C::f1}{(core::num*) →* void};
 }
 static method g2(self::C<core::int*>* c, core::Object* x) → void {
   (core::Object*) →* void f = self::g1(c) as (core::Object*) →* void;
   f(x){(core::Object*) →* void};
 }
 static method g3(self::C<core::num*>* c) → (core::List<core::num*>*) →* core::num* {
-  return c.{self::C::f2}{(core::List<core::num*>*) →* core::num*} as{TypeError,CovarianceCheck} (core::List<core::num*>*) →* core::num*;
+  return c.{self::C::f2}{(core::List<core::num*>*) →* core::num*};
 }
 static method test() → void {
   (core::num*) →* void x = self::g1(new self::C::•<core::int*>());
diff --git a/tools/VERSION b/tools/VERSION
index 766dd7a..dcb9cbd 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -27,5 +27,5 @@
 MAJOR 2
 MINOR 14
 PATCH 0
-PRERELEASE 392
+PRERELEASE 393
 PRERELEASE_PATCH 0
\ No newline at end of file