diff --git a/pkg/front_end/lib/src/fasta/kernel/constructor_tearoff_lowering.dart b/pkg/front_end/lib/src/fasta/kernel/constructor_tearoff_lowering.dart
index 1edef5737add..77159ce80bf0 100644
--- a/pkg/front_end/lib/src/fasta/kernel/constructor_tearoff_lowering.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/constructor_tearoff_lowering.dart
@@ -159,22 +159,41 @@ Procedure createTypedefTearOffProcedure(
       reference);
 }
 
-/// Creates the parameters and body for [tearOff] based on [constructor] in
-/// [enclosingClass].
-void buildConstructorTearOffProcedure(Procedure tearOff, Member constructor,
-    Class enclosingClass, SourceLibraryBuilder libraryBuilder) {
+/// Creates the parameters and body for [tearOff] based on
+/// [declarationConstructor] in [enclosingClass].
+///
+/// The [declarationConstructor] is the origin constructor and
+/// [implementationConstructor] is the patch constructor, if patched, otherwise
+/// it is the [declarationConstructor].
+void buildConstructorTearOffProcedure(
+    {required Procedure tearOff,
+    required Member declarationConstructor,
+    required Member implementationConstructor,
+    required Class enclosingClass,
+    required SourceLibraryBuilder libraryBuilder}) {
+  assert(
+      declarationConstructor is Constructor ||
+          (declarationConstructor is Procedure &&
+              declarationConstructor.isFactory) ||
+          (declarationConstructor is Procedure &&
+              declarationConstructor.isStatic),
+      "Unexpected constructor tear off target $declarationConstructor "
+      "(${declarationConstructor.runtimeType}).");
   assert(
-      constructor is Constructor ||
-          (constructor is Procedure && constructor.isFactory) ||
-          (constructor is Procedure && constructor.isStatic),
-      "Unexpected constructor tear off target $constructor "
-      "(${constructor.runtimeType}).");
+      declarationConstructor is Constructor ||
+          (declarationConstructor is Procedure &&
+              declarationConstructor.isFactory) ||
+          (declarationConstructor is Procedure &&
+              declarationConstructor.isStatic),
+      "Unexpected constructor tear off target $declarationConstructor "
+      "(${declarationConstructor.runtimeType}).");
+
+  FunctionNode function = implementationConstructor.function!;
 
   int fileOffset = tearOff.fileOffset;
 
-  FunctionNode function = constructor.function!;
   List<TypeParameter> classTypeParameters;
-  if (constructor is Constructor) {
+  if (declarationConstructor is Constructor) {
     // Generative constructors implicitly have the type parameters of the
     // enclosing class.
     classTypeParameters = enclosingClass.typeParameters;
@@ -189,37 +208,54 @@ void buildConstructorTearOffProcedure(Procedure tearOff, Member constructor,
 
   List<DartType> typeArguments = freshTypeParameters.freshTypeArguments;
   Substitution substitution = freshTypeParameters.substitution;
-  _createParameters(tearOff, constructor, substitution, libraryBuilder);
+  _createParameters(tearOff, implementationConstructor, function, substitution,
+      libraryBuilder);
   Arguments arguments = _createArguments(tearOff, typeArguments, fileOffset);
-  _createTearOffBody(tearOff, constructor, arguments);
+  _createTearOffBody(tearOff, declarationConstructor, arguments);
   tearOff.function.fileOffset = tearOff.fileOffset;
   tearOff.function.fileEndOffset = tearOff.fileOffset;
   updatePrivateMemberName(tearOff, libraryBuilder);
 }
 
 /// Creates the parameters and body for [tearOff] for a typedef tearoff of
-/// [constructor] in [enclosingClass] with [typeParameters] as the typedef
-/// parameters and [typeArguments] as the arguments passed to the
+/// [declarationConstructor] in [enclosingClass] with [typeParameters] as the
+/// typedef parameters and [typeArguments] as the arguments passed to the
 /// [enclosingClass].
+///
+/// The [declarationConstructor] is the origin constructor and
+/// [implementationConstructor] is the patch constructor, if patched, otherwise
+/// it is the [declarationConstructor].
 void buildTypedefTearOffProcedure(
-    Procedure tearOff,
-    Member constructor,
-    Class enclosingClass,
-    List<TypeParameter> typeParameters,
-    List<DartType> typeArguments,
-    SourceLibraryBuilder libraryBuilder) {
+    {required Procedure tearOff,
+    required Member declarationConstructor,
+    required Member implementationConstructor,
+    required Class enclosingClass,
+    required List<TypeParameter> typeParameters,
+    required List<DartType> typeArguments,
+    required SourceLibraryBuilder libraryBuilder}) {
   assert(
-      constructor is Constructor ||
-          (constructor is Procedure && constructor.isFactory) ||
-          (constructor is Procedure && constructor.isStatic),
-      "Unexpected constructor tear off target $constructor "
-      "(${constructor.runtimeType}).");
+      declarationConstructor is Constructor ||
+          (declarationConstructor is Procedure &&
+              declarationConstructor.isFactory) ||
+          (declarationConstructor is Procedure &&
+              declarationConstructor.isStatic),
+      "Unexpected constructor tear off target $declarationConstructor "
+      "(${declarationConstructor.runtimeType}).");
+  assert(
+      implementationConstructor is Constructor ||
+          (implementationConstructor is Procedure &&
+              implementationConstructor.isFactory) ||
+          (implementationConstructor is Procedure &&
+              implementationConstructor.isStatic),
+      "Unexpected constructor tear off target $implementationConstructor "
+      "(${declarationConstructor.runtimeType}).");
+
+  FunctionNode function = implementationConstructor.function!;
 
   int fileOffset = tearOff.fileOffset;
 
-  FunctionNode function = constructor.function!;
   List<TypeParameter> classTypeParameters;
-  if (constructor is Constructor) {
+  if (declarationConstructor is Constructor) {
     // Generative constructors implicitly have the type parameters of the
     // enclosing class.
     classTypeParameters = enclosingClass.typeParameters;
@@ -242,37 +278,43 @@ void buildTypedefTearOffProcedure(
   }
   _createParameters(
       tearOff,
-      constructor,
+      implementationConstructor,
+      function,
       Substitution.fromPairs(classTypeParameters, typeArguments),
       libraryBuilder);
   Arguments arguments = _createArguments(tearOff, typeArguments, fileOffset);
-  _createTearOffBody(tearOff, constructor, arguments);
+  _createTearOffBody(tearOff, declarationConstructor, arguments);
   tearOff.function.fileOffset = tearOff.fileOffset;
   tearOff.function.fileEndOffset = tearOff.fileOffset;
   updatePrivateMemberName(tearOff, libraryBuilder);
 }
 
 /// Creates the parameters for the redirecting factory [tearOff] based on the
-/// [redirectingConstructor] declaration.
+/// [declarationConstructor] declaration.
+///
+/// The [declarationConstructor] is the [Procedure] for the origin constructor
+/// and [implementationConstructorFunctionNode] is the [FunctionNode] for the
+/// implementation constructor. If the constructor is patched, these are not
+/// connected until [Builder.finishPatch].
 FreshTypeParameters buildRedirectingFactoryTearOffProcedureParameters(
-    Procedure tearOff,
-    Procedure redirectingConstructor,
-    SourceLibraryBuilder libraryBuilder) {
-  assert(redirectingConstructor.isRedirectingFactory);
-  FunctionNode function = redirectingConstructor.function;
+    {required Procedure tearOff,
+    required Procedure implementationConstructor,
+    required SourceLibraryBuilder libraryBuilder}) {
+  assert(implementationConstructor.isRedirectingFactory);
+  FunctionNode function = implementationConstructor.function;
   FreshTypeParameters freshTypeParameters =
       _createFreshTypeParameters(function.typeParameters, tearOff.function);
   Substitution substitution = freshTypeParameters.substitution;
-  _createParameters(
-      tearOff, redirectingConstructor, substitution, libraryBuilder);
+  _createParameters(tearOff, implementationConstructor, function, substitution,
+      libraryBuilder);
   tearOff.function.fileOffset = tearOff.fileOffset;
   tearOff.function.fileEndOffset = tearOff.fileOffset;
   updatePrivateMemberName(tearOff, libraryBuilder);
   return freshTypeParameters;
 }
 
-/// Creates the body for the redirecting factory [tearOff] with the target
-/// [constructor] and [typeArguments].
+/// Creates the body for the redirecting factory [tearOff] with the [target]
+/// constructor and [typeArguments].
 ///
 /// Returns the [DelayedDefaultValueCloner] object need to perform default value
 /// computation.
@@ -355,9 +397,12 @@ FreshTypeParameters _createFreshTypeParameters(
 /// Creates the parameters for the [tearOff] lowering based of the parameters
 /// in [constructor] and using the [substitution] to compute the parameter and
 /// return types.
-void _createParameters(Procedure tearOff, Member constructor,
-    Substitution substitution, SourceLibraryBuilder libraryBuilder) {
-  FunctionNode function = constructor.function!;
+void _createParameters(
+    Procedure tearOff,
+    Member constructor,
+    FunctionNode function,
+    Substitution substitution,
+    SourceLibraryBuilder libraryBuilder) {
   for (VariableDeclaration constructorParameter
       in function.positionalParameters) {
     VariableDeclaration tearOffParameter = new VariableDeclaration(
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_helper.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_helper.dart
index 75a94cf911c9..ffbbab7e74fa 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_helper.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_helper.dart
@@ -300,3 +300,39 @@ class TypeDependency {
     _hasBeenInferred = true;
   }
 }
+
+/// Copies properties, function parameters and body from the [patch] constructor
+/// to its [origin].
+void finishConstructorPatch(Constructor origin, Constructor patch) {
+  // TODO(ahe): restore file-offset once we track both origin and patch file
+  // URIs. See https://github.com/dart-lang/sdk/issues/31579
+  origin.fileUri = patch.fileUri;
+  origin.startFileOffset = patch.startFileOffset;
+  origin.fileOffset = patch.fileOffset;
+  origin.fileEndOffset = patch.fileEndOffset;
+  origin.annotations.forEach((m) => m.fileOffset = patch.fileOffset);
+
+  origin.isExternal = patch.isExternal;
+  origin.function = patch.function;
+  origin.function.parent = origin;
+  origin.initializers = patch.initializers;
+  setParents(origin.initializers, origin);
+}
+
+/// Copies properties, function parameters and body from the [patch] procedure
+/// to its [origin].
+void finishProcedurePatch(Procedure origin, Procedure patch) {
+  // TODO(ahe): restore file-offset once we track both origin and patch file
+  // URIs. See https://github.com/dart-lang/sdk/issues/31579
+  origin.fileUri = patch.fileUri;
+  origin.startFileOffset = patch.startFileOffset;
+  origin.fileOffset = patch.fileOffset;
+  origin.fileEndOffset = patch.fileEndOffset;
+  origin.annotations.forEach((m) => m.fileOffset = patch.fileOffset);
+
+  origin.isAbstract = patch.isAbstract;
+  origin.isExternal = patch.isExternal;
+  origin.function = patch.function;
+  origin.function.parent = origin;
+  origin.isRedirectingFactory = patch.isRedirectingFactory;
+}
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_target.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_target.dart
index 5794d255075f..c80faa19022a 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_target.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_target.dart
@@ -1092,8 +1092,12 @@ class KernelTarget extends TargetImplementation {
         forAbstractClassOrEnum: classBuilder.isAbstract);
 
     if (constructorTearOff != null) {
-      buildConstructorTearOffProcedure(constructorTearOff, constructor,
-          classBuilder.cls, classBuilder.libraryBuilder);
+      buildConstructorTearOffProcedure(
+          tearOff: constructorTearOff,
+          declarationConstructor: constructor,
+          implementationConstructor: constructor,
+          enclosingClass: classBuilder.cls,
+          libraryBuilder: classBuilder.libraryBuilder);
     }
     SyntheticSourceConstructorBuilder constructorBuilder =
         new SyntheticSourceConstructorBuilder(
@@ -1170,8 +1174,12 @@ class KernelTarget extends TargetImplementation {
         forAbstractClassOrEnum:
             enclosingClass.isAbstract || enclosingClass.isEnum);
     if (constructorTearOff != null) {
-      buildConstructorTearOffProcedure(constructorTearOff, constructor,
-          classBuilder.cls, classBuilder.libraryBuilder);
+      buildConstructorTearOffProcedure(
+          tearOff: constructorTearOff,
+          declarationConstructor: constructor,
+          implementationConstructor: constructor,
+          enclosingClass: classBuilder.cls,
+          libraryBuilder: classBuilder.libraryBuilder);
     }
     return new SyntheticSourceConstructorBuilder(
         classBuilder, constructor, constructorTearOff);
diff --git a/pkg/front_end/lib/src/fasta/source/source_constructor_builder.dart b/pkg/front_end/lib/src/fasta/source/source_constructor_builder.dart
index 3aa7702550c9..c0dadf6423f6 100644
--- a/pkg/front_end/lib/src/fasta/source/source_constructor_builder.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_constructor_builder.dart
@@ -27,7 +27,11 @@ import '../kernel/constructor_tearoff_lowering.dart';
 import '../kernel/expression_generator_helper.dart';
 import '../kernel/hierarchy/class_member.dart' show ClassMember;
 import '../kernel/kernel_helper.dart'
-    show DelayedDefaultValueCloner, TypeDependency;
+    show
+        DelayedDefaultValueCloner,
+        TypeDependency,
+        finishConstructorPatch,
+        finishProcedurePatch;
 import '../kernel/utils.dart'
     show isRedirectingGenerativeConstructorImplementation;
 import '../messages.dart'
@@ -202,8 +206,12 @@ class DeclaredSourceConstructorBuilder extends SourceFunctionBuilderImpl
       updatePrivateMemberName(_constructor, libraryBuilder);
 
       if (_constructorTearOff != null) {
-        buildConstructorTearOffProcedure(_constructorTearOff!, _constructor,
-            classBuilder.cls, libraryBuilder);
+        buildConstructorTearOffProcedure(
+            tearOff: _constructorTearOff!,
+            declarationConstructor: constructor,
+            implementationConstructor: _constructor,
+            enclosingClass: classBuilder.cls,
+            libraryBuilder: libraryBuilder);
       }
 
       _hasBeenBuilt = true;
@@ -660,20 +668,11 @@ class DeclaredSourceConstructorBuilder extends SourceFunctionBuilderImpl
   }
 
   void _finishPatch() {
-    // TODO(ahe): restore file-offset once we track both origin and patch file
-    // URIs. See https://github.com/dart-lang/sdk/issues/31579
-    origin.constructor.fileUri = fileUri;
-    origin.constructor.startFileOffset = _constructor.startFileOffset;
-    origin.constructor.fileOffset = _constructor.fileOffset;
-    origin.constructor.fileEndOffset = _constructor.fileEndOffset;
-    origin.constructor.annotations
-        .forEach((m) => m.fileOffset = _constructor.fileOffset);
-
-    origin.constructor.isExternal = _constructor.isExternal;
-    origin.constructor.function = _constructor.function;
-    origin.constructor.function.parent = origin.constructor;
-    origin.constructor.initializers = _constructor.initializers;
-    setParents(origin.constructor.initializers, origin.constructor);
+    finishConstructorPatch(origin.constructor, _constructor);
+
+    if (_constructorTearOff != null) {
+      finishProcedurePatch(origin._constructorTearOff!, _constructorTearOff!);
+    }
   }
 
   @override
diff --git a/pkg/front_end/lib/src/fasta/source/source_factory_builder.dart b/pkg/front_end/lib/src/fasta/source/source_factory_builder.dart
index cef67f3c936f..09523b6cc6c0 100644
--- a/pkg/front_end/lib/src/fasta/source/source_factory_builder.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_factory_builder.dart
@@ -151,8 +151,12 @@ class SourceFactoryBuilder extends SourceFunctionBuilderImpl {
     _procedureInternal.isStatic = isStatic;
 
     if (_factoryTearOff != null) {
-      buildConstructorTearOffProcedure(_factoryTearOff!, _procedureInternal,
-          classBuilder!.cls, libraryBuilder);
+      buildConstructorTearOffProcedure(
+          tearOff: _factoryTearOff!,
+          declarationConstructor: _procedure,
+          implementationConstructor: _procedureInternal,
+          enclosingClass: classBuilder!.cls,
+          libraryBuilder: libraryBuilder);
     }
     return _procedureInternal;
   }
@@ -224,21 +228,11 @@ class SourceFactoryBuilder extends SourceFunctionBuilderImpl {
   }
 
   void _finishPatch() {
-    // TODO(ahe): restore file-offset once we track both origin and patch file
-    // URIs. See https://github.com/dart-lang/sdk/issues/31579
-    origin._procedure.fileUri = fileUri;
-    origin._procedure.startFileOffset = _procedureInternal.startFileOffset;
-    origin._procedure.fileOffset = _procedureInternal.fileOffset;
-    origin._procedure.fileEndOffset = _procedureInternal.fileEndOffset;
-    origin._procedure.annotations
-        .forEach((m) => m.fileOffset = _procedureInternal.fileOffset);
-
-    origin._procedure.isAbstract = _procedureInternal.isAbstract;
-    origin._procedure.isExternal = _procedureInternal.isExternal;
-    origin._procedure.function = _procedureInternal.function;
-    origin._procedure.function.parent = origin._procedure;
-    origin._procedure.isRedirectingFactory =
-        _procedureInternal.isRedirectingFactory;
+    finishProcedurePatch(origin._procedure, _procedureInternal);
+
+    if (_factoryTearOff != null) {
+      finishProcedurePatch(origin._factoryTearOff!, _factoryTearOff!);
+    }
   }
 
   @override
@@ -373,7 +367,9 @@ class RedirectingFactoryBuilder extends SourceFactoryBuilder {
     if (_factoryTearOff != null) {
       _tearOffTypeParameters =
           buildRedirectingFactoryTearOffProcedureParameters(
-              _factoryTearOff!, _procedureInternal, libraryBuilder);
+              tearOff: _factoryTearOff!,
+              implementationConstructor: _procedureInternal,
+              libraryBuilder: libraryBuilder);
     }
     return _procedureInternal;
   }
diff --git a/pkg/front_end/lib/src/fasta/source/source_procedure_builder.dart b/pkg/front_end/lib/src/fasta/source/source_procedure_builder.dart
index 89731b694aef..1a7fe1f58ef3 100644
--- a/pkg/front_end/lib/src/fasta/source/source_procedure_builder.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_procedure_builder.dart
@@ -16,6 +16,7 @@ import '../builder/type_builder.dart';
 import '../builder/type_variable_builder.dart';
 import '../kernel/hierarchy/class_member.dart';
 import '../kernel/hierarchy/members_builder.dart';
+import '../kernel/kernel_helper.dart';
 import '../kernel/member_covariance.dart';
 import '../source/name_scheme.dart';
 import '../source/source_library_builder.dart' show SourceLibraryBuilder;
@@ -470,20 +471,7 @@ class SourceProcedureBuilder extends SourceFunctionBuilderImpl
   int finishPatch() {
     if (!isPatch) return 0;
 
-    // TODO(ahe): restore file-offset once we track both origin and patch file
-    // URIs. See https://github.com/dart-lang/sdk/issues/31579
-    origin.procedure.fileUri = fileUri;
-    origin.procedure.startFileOffset = _procedure.startFileOffset;
-    origin.procedure.fileOffset = _procedure.fileOffset;
-    origin.procedure.fileEndOffset = _procedure.fileEndOffset;
-    origin.procedure.annotations
-        .forEach((m) => m.fileOffset = _procedure.fileOffset);
-
-    origin.procedure.isAbstract = _procedure.isAbstract;
-    origin.procedure.isExternal = _procedure.isExternal;
-    origin.procedure.function = _procedure.function;
-    origin.procedure.function.parent = origin.procedure;
-    origin.procedure.isRedirectingFactory = _procedure.isRedirectingFactory;
+    finishProcedurePatch(origin.procedure, _procedure);
     return 1;
   }
 
diff --git a/pkg/front_end/lib/src/fasta/source/source_type_alias_builder.dart b/pkg/front_end/lib/src/fasta/source/source_type_alias_builder.dart
index 720a1b4691a4..c24455e73708 100644
--- a/pkg/front_end/lib/src/fasta/source/source_type_alias_builder.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_type_alias_builder.dart
@@ -4,7 +4,6 @@
 
 library fasta.source_type_alias_builder;
 
-import 'package:front_end/src/fasta/kernel/expression_generator_helper.dart';
 import 'package:kernel/ast.dart';
 import 'package:kernel/class_hierarchy.dart';
 import 'package:kernel/type_environment.dart';
@@ -24,6 +23,7 @@ import '../builder/type_variable_builder.dart';
 import '../fasta_codes.dart'
     show noLength, templateCyclicTypedef, templateTypeArgumentMismatch;
 import '../kernel/constructor_tearoff_lowering.dart';
+import '../kernel/expression_generator_helper.dart';
 import '../kernel/kernel_helper.dart';
 import '../problems.dart' show unhandled;
 import '../scope.dart';
@@ -275,14 +275,14 @@ class SourceTypeAliasBuilder extends TypeAliasBuilderImpl {
   Map<Procedure, Member>? _tearOffDependencies;
 
   void buildTypedefTearOffs(
-      SourceLibraryBuilder library, void Function(Procedure) f) {
+      SourceLibraryBuilder libraryBuilder, void Function(Procedure) f) {
     TypeDeclarationBuilder? declaration = unaliasDeclaration(null);
     DartType? targetType = typedef.type;
     if (declaration is ClassBuilder &&
         targetType is InterfaceType &&
         typedef.typeParameters.isNotEmpty &&
-        !isProperRenameForClass(
-            library.loader.typeEnvironment, typedef, library.library)) {
+        !isProperRenameForClass(libraryBuilder.loader.typeEnvironment, typedef,
+            libraryBuilder.library)) {
       tearOffs = {};
       _tearOffDependencies = {};
       declaration
@@ -295,19 +295,31 @@ class SourceTypeAliasBuilder extends TypeAliasBuilderImpl {
           Name targetName =
               new Name(constructorName, declaration.libraryBuilder.library);
           Reference? tearOffReference;
-          if (library.referencesFromIndexed != null) {
-            tearOffReference = library.referencesFromIndexed!
+          if (libraryBuilder.referencesFromIndexed != null) {
+            tearOffReference = libraryBuilder.referencesFromIndexed!
                 .lookupGetterReference(typedefTearOffName(name, constructorName,
-                    library.referencesFromIndexed!.library));
+                    libraryBuilder.referencesFromIndexed!.library));
           }
 
           Procedure tearOff = tearOffs![targetName] =
-              createTypedefTearOffProcedure(name, constructorName, library,
-                  target.fileUri, target.fileOffset, tearOffReference);
+              createTypedefTearOffProcedure(
+                  name,
+                  constructorName,
+                  libraryBuilder,
+                  target.fileUri,
+                  target.fileOffset,
+                  tearOffReference);
           _tearOffDependencies![tearOff] = target;
 
-          buildTypedefTearOffProcedure(tearOff, target, declaration.cls,
-              typedef.typeParameters, targetType.typeArguments, library);
+          buildTypedefTearOffProcedure(
+              tearOff: tearOff,
+              declarationConstructor: target,
+              // TODO(johnniwinther): Handle patched constructors.
+              implementationConstructor: target,
+              enclosingClass: declaration.cls,
+              typeParameters: typedef.typeParameters,
+              typeArguments: targetType.typeArguments,
+              libraryBuilder: libraryBuilder);
           f(tearOff);
         }
       });
diff --git a/pkg/front_end/testcases/dart2js/issue48776.dart b/pkg/front_end/testcases/dart2js/issue48776.dart
new file mode 100644
index 000000000000..5bad3b17ddcc
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/issue48776.dart
@@ -0,0 +1,7 @@
+// Copyright (c) 2022, 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.
+
+main() {
+  BigInt.from;
+}
diff --git a/pkg/front_end/testcases/dart2js/issue48776.dart.strong.expect b/pkg/front_end/testcases/dart2js/issue48776.dart.strong.expect
new file mode 100644
index 000000000000..7fd424849601
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/issue48776.dart.strong.expect
@@ -0,0 +1,11 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+static method main() → dynamic {
+  #C1;
+}
+
+constants  {
+  #C1 = static-tearoff core::BigInt::_#from#tearOff
+}
diff --git a/pkg/front_end/testcases/dart2js/issue48776.dart.strong.transformed.expect b/pkg/front_end/testcases/dart2js/issue48776.dart.strong.transformed.expect
new file mode 100644
index 000000000000..7fd424849601
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/issue48776.dart.strong.transformed.expect
@@ -0,0 +1,11 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+static method main() → dynamic {
+  #C1;
+}
+
+constants  {
+  #C1 = static-tearoff core::BigInt::_#from#tearOff
+}
diff --git a/pkg/front_end/testcases/dart2js/issue48776.dart.textual_outline.expect b/pkg/front_end/testcases/dart2js/issue48776.dart.textual_outline.expect
new file mode 100644
index 000000000000..bae895adcb68
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/issue48776.dart.textual_outline.expect
@@ -0,0 +1 @@
+main() {}
diff --git a/pkg/front_end/testcases/dart2js/issue48776.dart.textual_outline_modelled.expect b/pkg/front_end/testcases/dart2js/issue48776.dart.textual_outline_modelled.expect
new file mode 100644
index 000000000000..bae895adcb68
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/issue48776.dart.textual_outline_modelled.expect
@@ -0,0 +1 @@
+main() {}
diff --git a/pkg/front_end/testcases/dart2js/issue48776.dart.weak.expect b/pkg/front_end/testcases/dart2js/issue48776.dart.weak.expect
new file mode 100644
index 000000000000..7fd424849601
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/issue48776.dart.weak.expect
@@ -0,0 +1,11 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+static method main() → dynamic {
+  #C1;
+}
+
+constants  {
+  #C1 = static-tearoff core::BigInt::_#from#tearOff
+}
diff --git a/pkg/front_end/testcases/dart2js/issue48776.dart.weak.modular.expect b/pkg/front_end/testcases/dart2js/issue48776.dart.weak.modular.expect
new file mode 100644
index 000000000000..7fd424849601
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/issue48776.dart.weak.modular.expect
@@ -0,0 +1,11 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+static method main() → dynamic {
+  #C1;
+}
+
+constants  {
+  #C1 = static-tearoff core::BigInt::_#from#tearOff
+}
diff --git a/pkg/front_end/testcases/dart2js/issue48776.dart.weak.outline.expect b/pkg/front_end/testcases/dart2js/issue48776.dart.weak.outline.expect
new file mode 100644
index 000000000000..e2cba6be4d13
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/issue48776.dart.weak.outline.expect
@@ -0,0 +1,5 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method main() → dynamic
+  ;
diff --git a/pkg/front_end/testcases/dart2js/issue48776.dart.weak.transformed.expect b/pkg/front_end/testcases/dart2js/issue48776.dart.weak.transformed.expect
new file mode 100644
index 000000000000..7fd424849601
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/issue48776.dart.weak.transformed.expect
@@ -0,0 +1,11 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+static method main() → dynamic {
+  #C1;
+}
+
+constants  {
+  #C1 = static-tearoff core::BigInt::_#from#tearOff
+}
diff --git a/pkg/front_end/testcases/dart2js/tear_off_patch/libraries.json b/pkg/front_end/testcases/dart2js/tear_off_patch/libraries.json
new file mode 100644
index 000000000000..154c73c30b2b
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/tear_off_patch/libraries.json
@@ -0,0 +1,12 @@
+{
+  "none": {
+    "libraries": {
+      "test": {
+        "patches": [
+          "patch_lib.dart"
+        ],
+        "uri": "origin_lib.dart"
+      }
+    }
+  }
+}
diff --git a/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart
new file mode 100644
index 000000000000..676f68ab0f39
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart
@@ -0,0 +1,20 @@
+// Copyright (c) 2022, 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.
+
+import 'dart:test';
+
+main() {
+  Class.new;
+  Class.fact;
+  Class.redirect;
+  Class.redirect2;
+  ClassImpl.new;
+  ClassImpl.patched;
+  Alias.new;
+  Alias.fact;
+  Alias.redirect;
+  Alias.redirect2;
+  AliasImpl.new;
+  AliasImpl.patched;
+}
diff --git a/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.strong.expect b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.strong.expect
new file mode 100644
index 000000000000..3ba9f8689061
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.strong.expect
@@ -0,0 +1,104 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  #C1;
+  #C2;
+  #C3;
+  #C4;
+  #C5;
+  #C6;
+  #C7;
+  #C8;
+  #C9;
+  #C10;
+  #C11;
+  #C12;
+}
+
+library /*isNonNullableByDefault*/;
+import self as test;
+import "dart:core" as core;
+import "dart:_js_helper" as _js;
+
+import "dart:_js_helper";
+
+typedef Alias<T extends core::num> = test::Class<T>;
+typedef AliasImpl<T extends core::num> = test::ClassImpl<T>;
+@#C13
+class Class<T extends core::Object? = dynamic> extends core::Object {
+  static final field dynamic _redirecting# = <dynamic>[#C14, #C15]/*isLegacy*/;
+  @#C13
+  constructor •({core::bool defaultValue = #C16, required test::Class::T% value = #C17}) → test::Class<test::Class::T%>
+    : super core::Object::•() {
+    core::print("patch Class");
+  }
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#new#tearOff::T% value = #C17}) → test::Class<test::Class::_#new#tearOff::T%>
+    return new test::Class::•<test::Class::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::fact::T% value = #C17}) → test::Class<test::Class::fact::T%>
+    return new test::ClassImpl::•<test::Class::fact::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#fact#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#fact#tearOff::T% value = #C17}) → test::Class<test::Class::_#fact#tearOff::T%>
+    return test::Class::fact<test::Class::_#fact#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect::T% value = #C17}) → test::Class<test::Class::redirect::T%>
+    return new test::ClassImpl::•<test::Class::redirect::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect#tearOff::T%>
+    return new test::ClassImpl::•<test::Class::_#redirect#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect2<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect2::T% value = #C17}) → test::Class<test::Class::redirect2::T%>
+    return new test::ClassImpl::patched<test::Class::redirect2::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect2#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect2#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect2#tearOff::T%>
+    return new test::ClassImpl::patched<test::Class::_#redirect2#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+@#C13
+class ClassImpl<T extends core::Object? = dynamic> extends core::Object implements test::Class<test::ClassImpl::T%> {
+  constructor •({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•()
+    ;
+  @#C13
+  constructor patched({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•() {
+    core::print("patch ClassImpl");
+  }
+  static method _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#new#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#new#tearOff::T%>
+    return new test::ClassImpl::•<test::ClassImpl::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#patched#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#patched#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#patched#tearOff::T%>
+    return new test::ClassImpl::patched<test::ClassImpl::_#patched#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+static method _#Alias#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#new#tearOff::T value = #C17}) → test::Class<test::_#Alias#new#tearOff::T>
+  return new test::Class::•<test::_#Alias#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#fact#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#fact#tearOff::T value = #C17}) → test::Class<test::_#Alias#fact#tearOff::T>
+  return test::Class::fact<test::_#Alias#fact#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect#tearOff::T>
+  return test::Class::_#redirect#tearOff<test::_#Alias#redirect#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect2#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect2#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect2#tearOff::T>
+  return test::Class::_#redirect2#tearOff<test::_#Alias#redirect2#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#new#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#new#tearOff::T>
+  return new test::ClassImpl::•<test::_#AliasImpl#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#patched#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#patched#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#patched#tearOff::T>
+  return new test::ClassImpl::patched<test::_#AliasImpl#patched#tearOff::T>(defaultValue: defaultValue, value: value);
+
+constants  {
+  #C1 = static-tearoff test::Class::_#new#tearOff
+  #C2 = static-tearoff test::Class::_#fact#tearOff
+  #C3 = static-tearoff test::Class::_#redirect#tearOff
+  #C4 = static-tearoff test::Class::_#redirect2#tearOff
+  #C5 = static-tearoff test::ClassImpl::_#new#tearOff
+  #C6 = static-tearoff test::ClassImpl::_#patched#tearOff
+  #C7 = static-tearoff test::_#Alias#new#tearOff
+  #C8 = static-tearoff test::_#Alias#fact#tearOff
+  #C9 = static-tearoff test::_#Alias#redirect#tearOff
+  #C10 = static-tearoff test::_#Alias#redirect2#tearOff
+  #C11 = static-tearoff test::_#AliasImpl#new#tearOff
+  #C12 = static-tearoff test::_#AliasImpl#patched#tearOff
+  #C13 = _js::_Patch {}
+  #C14 = constructor-tearoff test::Class::redirect
+  #C15 = constructor-tearoff test::Class::redirect2
+  #C16 = true
+  #C17 = null
+}
diff --git a/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.strong.transformed.expect b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.strong.transformed.expect
new file mode 100644
index 000000000000..3ba9f8689061
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.strong.transformed.expect
@@ -0,0 +1,104 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  #C1;
+  #C2;
+  #C3;
+  #C4;
+  #C5;
+  #C6;
+  #C7;
+  #C8;
+  #C9;
+  #C10;
+  #C11;
+  #C12;
+}
+
+library /*isNonNullableByDefault*/;
+import self as test;
+import "dart:core" as core;
+import "dart:_js_helper" as _js;
+
+import "dart:_js_helper";
+
+typedef Alias<T extends core::num> = test::Class<T>;
+typedef AliasImpl<T extends core::num> = test::ClassImpl<T>;
+@#C13
+class Class<T extends core::Object? = dynamic> extends core::Object {
+  static final field dynamic _redirecting# = <dynamic>[#C14, #C15]/*isLegacy*/;
+  @#C13
+  constructor •({core::bool defaultValue = #C16, required test::Class::T% value = #C17}) → test::Class<test::Class::T%>
+    : super core::Object::•() {
+    core::print("patch Class");
+  }
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#new#tearOff::T% value = #C17}) → test::Class<test::Class::_#new#tearOff::T%>
+    return new test::Class::•<test::Class::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::fact::T% value = #C17}) → test::Class<test::Class::fact::T%>
+    return new test::ClassImpl::•<test::Class::fact::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#fact#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#fact#tearOff::T% value = #C17}) → test::Class<test::Class::_#fact#tearOff::T%>
+    return test::Class::fact<test::Class::_#fact#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect::T% value = #C17}) → test::Class<test::Class::redirect::T%>
+    return new test::ClassImpl::•<test::Class::redirect::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect#tearOff::T%>
+    return new test::ClassImpl::•<test::Class::_#redirect#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect2<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect2::T% value = #C17}) → test::Class<test::Class::redirect2::T%>
+    return new test::ClassImpl::patched<test::Class::redirect2::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect2#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect2#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect2#tearOff::T%>
+    return new test::ClassImpl::patched<test::Class::_#redirect2#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+@#C13
+class ClassImpl<T extends core::Object? = dynamic> extends core::Object implements test::Class<test::ClassImpl::T%> {
+  constructor •({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•()
+    ;
+  @#C13
+  constructor patched({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•() {
+    core::print("patch ClassImpl");
+  }
+  static method _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#new#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#new#tearOff::T%>
+    return new test::ClassImpl::•<test::ClassImpl::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#patched#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#patched#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#patched#tearOff::T%>
+    return new test::ClassImpl::patched<test::ClassImpl::_#patched#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+static method _#Alias#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#new#tearOff::T value = #C17}) → test::Class<test::_#Alias#new#tearOff::T>
+  return new test::Class::•<test::_#Alias#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#fact#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#fact#tearOff::T value = #C17}) → test::Class<test::_#Alias#fact#tearOff::T>
+  return test::Class::fact<test::_#Alias#fact#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect#tearOff::T>
+  return test::Class::_#redirect#tearOff<test::_#Alias#redirect#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect2#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect2#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect2#tearOff::T>
+  return test::Class::_#redirect2#tearOff<test::_#Alias#redirect2#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#new#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#new#tearOff::T>
+  return new test::ClassImpl::•<test::_#AliasImpl#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#patched#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#patched#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#patched#tearOff::T>
+  return new test::ClassImpl::patched<test::_#AliasImpl#patched#tearOff::T>(defaultValue: defaultValue, value: value);
+
+constants  {
+  #C1 = static-tearoff test::Class::_#new#tearOff
+  #C2 = static-tearoff test::Class::_#fact#tearOff
+  #C3 = static-tearoff test::Class::_#redirect#tearOff
+  #C4 = static-tearoff test::Class::_#redirect2#tearOff
+  #C5 = static-tearoff test::ClassImpl::_#new#tearOff
+  #C6 = static-tearoff test::ClassImpl::_#patched#tearOff
+  #C7 = static-tearoff test::_#Alias#new#tearOff
+  #C8 = static-tearoff test::_#Alias#fact#tearOff
+  #C9 = static-tearoff test::_#Alias#redirect#tearOff
+  #C10 = static-tearoff test::_#Alias#redirect2#tearOff
+  #C11 = static-tearoff test::_#AliasImpl#new#tearOff
+  #C12 = static-tearoff test::_#AliasImpl#patched#tearOff
+  #C13 = _js::_Patch {}
+  #C14 = constructor-tearoff test::Class::redirect
+  #C15 = constructor-tearoff test::Class::redirect2
+  #C16 = true
+  #C17 = null
+}
diff --git a/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.textual_outline.expect b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.textual_outline.expect
new file mode 100644
index 000000000000..3c9c90e9437e
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.textual_outline.expect
@@ -0,0 +1,3 @@
+import 'dart:test';
+
+main() {}
diff --git a/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.textual_outline_modelled.expect b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.textual_outline_modelled.expect
new file mode 100644
index 000000000000..3c9c90e9437e
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.textual_outline_modelled.expect
@@ -0,0 +1,3 @@
+import 'dart:test';
+
+main() {}
diff --git a/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.weak.expect b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.weak.expect
new file mode 100644
index 000000000000..3ba9f8689061
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.weak.expect
@@ -0,0 +1,104 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  #C1;
+  #C2;
+  #C3;
+  #C4;
+  #C5;
+  #C6;
+  #C7;
+  #C8;
+  #C9;
+  #C10;
+  #C11;
+  #C12;
+}
+
+library /*isNonNullableByDefault*/;
+import self as test;
+import "dart:core" as core;
+import "dart:_js_helper" as _js;
+
+import "dart:_js_helper";
+
+typedef Alias<T extends core::num> = test::Class<T>;
+typedef AliasImpl<T extends core::num> = test::ClassImpl<T>;
+@#C13
+class Class<T extends core::Object? = dynamic> extends core::Object {
+  static final field dynamic _redirecting# = <dynamic>[#C14, #C15]/*isLegacy*/;
+  @#C13
+  constructor •({core::bool defaultValue = #C16, required test::Class::T% value = #C17}) → test::Class<test::Class::T%>
+    : super core::Object::•() {
+    core::print("patch Class");
+  }
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#new#tearOff::T% value = #C17}) → test::Class<test::Class::_#new#tearOff::T%>
+    return new test::Class::•<test::Class::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::fact::T% value = #C17}) → test::Class<test::Class::fact::T%>
+    return new test::ClassImpl::•<test::Class::fact::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#fact#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#fact#tearOff::T% value = #C17}) → test::Class<test::Class::_#fact#tearOff::T%>
+    return test::Class::fact<test::Class::_#fact#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect::T% value = #C17}) → test::Class<test::Class::redirect::T%>
+    return new test::ClassImpl::•<test::Class::redirect::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect#tearOff::T%>
+    return new test::ClassImpl::•<test::Class::_#redirect#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect2<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect2::T% value = #C17}) → test::Class<test::Class::redirect2::T%>
+    return new test::ClassImpl::patched<test::Class::redirect2::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect2#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect2#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect2#tearOff::T%>
+    return new test::ClassImpl::patched<test::Class::_#redirect2#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+@#C13
+class ClassImpl<T extends core::Object? = dynamic> extends core::Object implements test::Class<test::ClassImpl::T%> {
+  constructor •({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•()
+    ;
+  @#C13
+  constructor patched({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•() {
+    core::print("patch ClassImpl");
+  }
+  static method _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#new#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#new#tearOff::T%>
+    return new test::ClassImpl::•<test::ClassImpl::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#patched#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#patched#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#patched#tearOff::T%>
+    return new test::ClassImpl::patched<test::ClassImpl::_#patched#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+static method _#Alias#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#new#tearOff::T value = #C17}) → test::Class<test::_#Alias#new#tearOff::T>
+  return new test::Class::•<test::_#Alias#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#fact#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#fact#tearOff::T value = #C17}) → test::Class<test::_#Alias#fact#tearOff::T>
+  return test::Class::fact<test::_#Alias#fact#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect#tearOff::T>
+  return test::Class::_#redirect#tearOff<test::_#Alias#redirect#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect2#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect2#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect2#tearOff::T>
+  return test::Class::_#redirect2#tearOff<test::_#Alias#redirect2#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#new#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#new#tearOff::T>
+  return new test::ClassImpl::•<test::_#AliasImpl#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#patched#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#patched#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#patched#tearOff::T>
+  return new test::ClassImpl::patched<test::_#AliasImpl#patched#tearOff::T>(defaultValue: defaultValue, value: value);
+
+constants  {
+  #C1 = static-tearoff test::Class::_#new#tearOff
+  #C2 = static-tearoff test::Class::_#fact#tearOff
+  #C3 = static-tearoff test::Class::_#redirect#tearOff
+  #C4 = static-tearoff test::Class::_#redirect2#tearOff
+  #C5 = static-tearoff test::ClassImpl::_#new#tearOff
+  #C6 = static-tearoff test::ClassImpl::_#patched#tearOff
+  #C7 = static-tearoff test::_#Alias#new#tearOff
+  #C8 = static-tearoff test::_#Alias#fact#tearOff
+  #C9 = static-tearoff test::_#Alias#redirect#tearOff
+  #C10 = static-tearoff test::_#Alias#redirect2#tearOff
+  #C11 = static-tearoff test::_#AliasImpl#new#tearOff
+  #C12 = static-tearoff test::_#AliasImpl#patched#tearOff
+  #C13 = _js::_Patch {}
+  #C14 = constructor-tearoff test::Class::redirect
+  #C15 = constructor-tearoff test::Class::redirect2
+  #C16 = true
+  #C17 = null
+}
diff --git a/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.weak.modular.expect b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.weak.modular.expect
new file mode 100644
index 000000000000..3ba9f8689061
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.weak.modular.expect
@@ -0,0 +1,104 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  #C1;
+  #C2;
+  #C3;
+  #C4;
+  #C5;
+  #C6;
+  #C7;
+  #C8;
+  #C9;
+  #C10;
+  #C11;
+  #C12;
+}
+
+library /*isNonNullableByDefault*/;
+import self as test;
+import "dart:core" as core;
+import "dart:_js_helper" as _js;
+
+import "dart:_js_helper";
+
+typedef Alias<T extends core::num> = test::Class<T>;
+typedef AliasImpl<T extends core::num> = test::ClassImpl<T>;
+@#C13
+class Class<T extends core::Object? = dynamic> extends core::Object {
+  static final field dynamic _redirecting# = <dynamic>[#C14, #C15]/*isLegacy*/;
+  @#C13
+  constructor •({core::bool defaultValue = #C16, required test::Class::T% value = #C17}) → test::Class<test::Class::T%>
+    : super core::Object::•() {
+    core::print("patch Class");
+  }
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#new#tearOff::T% value = #C17}) → test::Class<test::Class::_#new#tearOff::T%>
+    return new test::Class::•<test::Class::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::fact::T% value = #C17}) → test::Class<test::Class::fact::T%>
+    return new test::ClassImpl::•<test::Class::fact::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#fact#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#fact#tearOff::T% value = #C17}) → test::Class<test::Class::_#fact#tearOff::T%>
+    return test::Class::fact<test::Class::_#fact#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect::T% value = #C17}) → test::Class<test::Class::redirect::T%>
+    return new test::ClassImpl::•<test::Class::redirect::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect#tearOff::T%>
+    return new test::ClassImpl::•<test::Class::_#redirect#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect2<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect2::T% value = #C17}) → test::Class<test::Class::redirect2::T%>
+    return new test::ClassImpl::patched<test::Class::redirect2::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect2#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect2#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect2#tearOff::T%>
+    return new test::ClassImpl::patched<test::Class::_#redirect2#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+@#C13
+class ClassImpl<T extends core::Object? = dynamic> extends core::Object implements test::Class<test::ClassImpl::T%> {
+  constructor •({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•()
+    ;
+  @#C13
+  constructor patched({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•() {
+    core::print("patch ClassImpl");
+  }
+  static method _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#new#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#new#tearOff::T%>
+    return new test::ClassImpl::•<test::ClassImpl::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#patched#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#patched#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#patched#tearOff::T%>
+    return new test::ClassImpl::patched<test::ClassImpl::_#patched#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+static method _#Alias#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#new#tearOff::T value = #C17}) → test::Class<test::_#Alias#new#tearOff::T>
+  return new test::Class::•<test::_#Alias#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#fact#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#fact#tearOff::T value = #C17}) → test::Class<test::_#Alias#fact#tearOff::T>
+  return test::Class::fact<test::_#Alias#fact#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect#tearOff::T>
+  return test::Class::_#redirect#tearOff<test::_#Alias#redirect#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect2#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect2#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect2#tearOff::T>
+  return test::Class::_#redirect2#tearOff<test::_#Alias#redirect2#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#new#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#new#tearOff::T>
+  return new test::ClassImpl::•<test::_#AliasImpl#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#patched#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#patched#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#patched#tearOff::T>
+  return new test::ClassImpl::patched<test::_#AliasImpl#patched#tearOff::T>(defaultValue: defaultValue, value: value);
+
+constants  {
+  #C1 = static-tearoff test::Class::_#new#tearOff
+  #C2 = static-tearoff test::Class::_#fact#tearOff
+  #C3 = static-tearoff test::Class::_#redirect#tearOff
+  #C4 = static-tearoff test::Class::_#redirect2#tearOff
+  #C5 = static-tearoff test::ClassImpl::_#new#tearOff
+  #C6 = static-tearoff test::ClassImpl::_#patched#tearOff
+  #C7 = static-tearoff test::_#Alias#new#tearOff
+  #C8 = static-tearoff test::_#Alias#fact#tearOff
+  #C9 = static-tearoff test::_#Alias#redirect#tearOff
+  #C10 = static-tearoff test::_#Alias#redirect2#tearOff
+  #C11 = static-tearoff test::_#AliasImpl#new#tearOff
+  #C12 = static-tearoff test::_#AliasImpl#patched#tearOff
+  #C13 = _js::_Patch {}
+  #C14 = constructor-tearoff test::Class::redirect
+  #C15 = constructor-tearoff test::Class::redirect2
+  #C16 = true
+  #C17 = null
+}
diff --git a/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.weak.outline.expect b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.weak.outline.expect
new file mode 100644
index 000000000000..49786e999040
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.weak.outline.expect
@@ -0,0 +1,77 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+import "dart:test";
+
+static method main() → dynamic
+  ;
+
+library /*isNonNullableByDefault*/;
+import self as self2;
+import "dart:core" as core;
+import "dart:_js_helper" as _js;
+
+import "dart:_js_helper";
+
+typedef Alias<T extends core::num> = self2::Class<T>;
+typedef AliasImpl<T extends core::num> = self2::ClassImpl<T>;
+@_js::patch
+class Class<T extends core::Object? = dynamic> extends core::Object {
+  static final field dynamic _redirecting# = <dynamic>[self2::Class::redirect, self2::Class::redirect2]/*isLegacy*/;
+  @_js::patch
+  external constructor •({core::bool defaultValue = true, required self2::Class::T% value = null}) → self2::Class<self2::Class::T%>
+    ;
+  static method _#new#tearOff<T extends core::Object? = dynamic>({has-declared-initializer core::bool defaultValue, required self2::Class::_#new#tearOff::T% value}) → self2::Class<self2::Class::_#new#tearOff::T%>
+    return new self2::Class::•<self2::Class::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @_js::patch
+  external static factory fact<T extends core::Object? = dynamic>({has-declared-initializer core::bool defaultValue, required self2::Class::fact::T% value}) → self2::Class<self2::Class::fact::T%>;
+  static method _#fact#tearOff<T extends core::Object? = dynamic>({has-declared-initializer core::bool defaultValue, required self2::Class::_#fact#tearOff::T% value}) → self2::Class<self2::Class::_#fact#tearOff::T%>
+    return self2::Class::fact<self2::Class::_#fact#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @_js::patch
+  external static factory redirect<T extends core::Object? = dynamic>({core::bool defaultValue, required self2::Class::redirect::T% value}) → self2::Class<self2::Class::redirect::T%>
+    return new self2::ClassImpl::•<self2::Class::redirect::T%>(defaultValue: defaultValue, value: value);
+  static method _#redirect#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue, required self2::Class::_#redirect#tearOff::T% value}) → self2::Class<self2::Class::_#redirect#tearOff::T%>
+    return self2::Class::redirect<self2::Class::_#redirect#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @_js::patch
+  external static factory redirect2<T extends core::Object? = dynamic>({core::bool defaultValue, required self2::Class::redirect2::T% value}) → self2::Class<self2::Class::redirect2::T%>
+    return new self2::ClassImpl::patched<self2::Class::redirect2::T%>(defaultValue: defaultValue, value: value);
+  static method _#redirect2#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue, required self2::Class::_#redirect2#tearOff::T% value}) → self2::Class<self2::Class::_#redirect2#tearOff::T%>
+    return self2::Class::redirect2<self2::Class::_#redirect2#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+@_js::patch
+class ClassImpl<T extends core::Object? = dynamic> extends core::Object implements self2::Class<self2::ClassImpl::T%> {
+  constructor •({core::bool defaultValue = true, required self2::ClassImpl::T% value = null}) → self2::ClassImpl<self2::ClassImpl::T%>
+    ;
+  @_js::patch
+  external constructor patched({core::bool defaultValue = true, required self2::ClassImpl::T% value = null}) → self2::ClassImpl<self2::ClassImpl::T%>
+    ;
+  static method _#new#tearOff<T extends core::Object? = dynamic>({has-declared-initializer core::bool defaultValue, required self2::ClassImpl::_#new#tearOff::T% value}) → self2::ClassImpl<self2::ClassImpl::_#new#tearOff::T%>
+    return new self2::ClassImpl::•<self2::ClassImpl::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  static method _#patched#tearOff<T extends core::Object? = dynamic>({has-declared-initializer core::bool defaultValue, required self2::ClassImpl::_#patched#tearOff::T% value}) → self2::ClassImpl<self2::ClassImpl::_#patched#tearOff::T%>
+    return new self2::ClassImpl::patched<self2::ClassImpl::_#patched#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+static method _#Alias#new#tearOff<T extends core::num>({has-declared-initializer core::bool defaultValue, required self2::_#Alias#new#tearOff::T value}) → self2::Class<self2::_#Alias#new#tearOff::T>
+  return new self2::Class::•<self2::_#Alias#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#fact#tearOff<T extends core::num>({has-declared-initializer core::bool defaultValue, required self2::_#Alias#fact#tearOff::T value}) → self2::Class<self2::_#Alias#fact#tearOff::T>
+  return self2::Class::fact<self2::_#Alias#fact#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect#tearOff<T extends core::num>({core::bool defaultValue, required self2::_#Alias#redirect#tearOff::T value}) → self2::Class<self2::_#Alias#redirect#tearOff::T>
+  return self2::Class::_#redirect#tearOff<self2::_#Alias#redirect#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect2#tearOff<T extends core::num>({core::bool defaultValue, required self2::_#Alias#redirect2#tearOff::T value}) → self2::Class<self2::_#Alias#redirect2#tearOff::T>
+  return self2::Class::_#redirect2#tearOff<self2::_#Alias#redirect2#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#new#tearOff<T extends core::num>({has-declared-initializer core::bool defaultValue, required self2::_#AliasImpl#new#tearOff::T value}) → self2::ClassImpl<self2::_#AliasImpl#new#tearOff::T>
+  return new self2::ClassImpl::•<self2::_#AliasImpl#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#patched#tearOff<T extends core::num>({has-declared-initializer core::bool defaultValue, required self2::_#AliasImpl#patched#tearOff::T value}) → self2::ClassImpl<self2::_#AliasImpl#patched#tearOff::T>
+  return new self2::ClassImpl::patched<self2::_#AliasImpl#patched#tearOff::T>(defaultValue: defaultValue, value: value);
+
+
+Extra constant evaluation status:
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:6:47 -> InstanceConstant(const _Patch{})
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:7:10 -> InstanceConstant(const _Patch{})
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:8:29 -> InstanceConstant(const _Patch{})
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:12:22 -> InstanceConstant(const _Patch{})
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:15:12 -> InstanceConstant(const _Patch{})
+Evaluated: ConstructorTearOff @ org-dartlang-testcase:///origin_lib.dart:5:7 -> ConstructorTearOffConstant(Class.redirect)
+Evaluated: ConstructorTearOff @ org-dartlang-testcase:///origin_lib.dart:5:7 -> ConstructorTearOffConstant(Class.redirect2)
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:18:39 -> InstanceConstant(const _Patch{})
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:19:48 -> InstanceConstant(const _Patch{})
+Extra constant evaluation: evaluated: 52, effectively constant: 9
diff --git a/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.weak.transformed.expect b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.weak.transformed.expect
new file mode 100644
index 000000000000..3ba9f8689061
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/tear_off_patch/main.dart.weak.transformed.expect
@@ -0,0 +1,104 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  #C1;
+  #C2;
+  #C3;
+  #C4;
+  #C5;
+  #C6;
+  #C7;
+  #C8;
+  #C9;
+  #C10;
+  #C11;
+  #C12;
+}
+
+library /*isNonNullableByDefault*/;
+import self as test;
+import "dart:core" as core;
+import "dart:_js_helper" as _js;
+
+import "dart:_js_helper";
+
+typedef Alias<T extends core::num> = test::Class<T>;
+typedef AliasImpl<T extends core::num> = test::ClassImpl<T>;
+@#C13
+class Class<T extends core::Object? = dynamic> extends core::Object {
+  static final field dynamic _redirecting# = <dynamic>[#C14, #C15]/*isLegacy*/;
+  @#C13
+  constructor •({core::bool defaultValue = #C16, required test::Class::T% value = #C17}) → test::Class<test::Class::T%>
+    : super core::Object::•() {
+    core::print("patch Class");
+  }
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#new#tearOff::T% value = #C17}) → test::Class<test::Class::_#new#tearOff::T%>
+    return new test::Class::•<test::Class::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::fact::T% value = #C17}) → test::Class<test::Class::fact::T%>
+    return new test::ClassImpl::•<test::Class::fact::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#fact#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#fact#tearOff::T% value = #C17}) → test::Class<test::Class::_#fact#tearOff::T%>
+    return test::Class::fact<test::Class::_#fact#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect::T% value = #C17}) → test::Class<test::Class::redirect::T%>
+    return new test::ClassImpl::•<test::Class::redirect::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect#tearOff::T%>
+    return new test::ClassImpl::•<test::Class::_#redirect#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect2<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect2::T% value = #C17}) → test::Class<test::Class::redirect2::T%>
+    return new test::ClassImpl::patched<test::Class::redirect2::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect2#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect2#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect2#tearOff::T%>
+    return new test::ClassImpl::patched<test::Class::_#redirect2#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+@#C13
+class ClassImpl<T extends core::Object? = dynamic> extends core::Object implements test::Class<test::ClassImpl::T%> {
+  constructor •({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•()
+    ;
+  @#C13
+  constructor patched({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•() {
+    core::print("patch ClassImpl");
+  }
+  static method _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#new#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#new#tearOff::T%>
+    return new test::ClassImpl::•<test::ClassImpl::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#patched#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#patched#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#patched#tearOff::T%>
+    return new test::ClassImpl::patched<test::ClassImpl::_#patched#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+static method _#Alias#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#new#tearOff::T value = #C17}) → test::Class<test::_#Alias#new#tearOff::T>
+  return new test::Class::•<test::_#Alias#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#fact#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#fact#tearOff::T value = #C17}) → test::Class<test::_#Alias#fact#tearOff::T>
+  return test::Class::fact<test::_#Alias#fact#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect#tearOff::T>
+  return test::Class::_#redirect#tearOff<test::_#Alias#redirect#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect2#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect2#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect2#tearOff::T>
+  return test::Class::_#redirect2#tearOff<test::_#Alias#redirect2#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#new#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#new#tearOff::T>
+  return new test::ClassImpl::•<test::_#AliasImpl#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#patched#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#patched#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#patched#tearOff::T>
+  return new test::ClassImpl::patched<test::_#AliasImpl#patched#tearOff::T>(defaultValue: defaultValue, value: value);
+
+constants  {
+  #C1 = static-tearoff test::Class::_#new#tearOff
+  #C2 = static-tearoff test::Class::_#fact#tearOff
+  #C3 = static-tearoff test::Class::_#redirect#tearOff
+  #C4 = static-tearoff test::Class::_#redirect2#tearOff
+  #C5 = static-tearoff test::ClassImpl::_#new#tearOff
+  #C6 = static-tearoff test::ClassImpl::_#patched#tearOff
+  #C7 = static-tearoff test::_#Alias#new#tearOff
+  #C8 = static-tearoff test::_#Alias#fact#tearOff
+  #C9 = static-tearoff test::_#Alias#redirect#tearOff
+  #C10 = static-tearoff test::_#Alias#redirect2#tearOff
+  #C11 = static-tearoff test::_#AliasImpl#new#tearOff
+  #C12 = static-tearoff test::_#AliasImpl#patched#tearOff
+  #C13 = _js::_Patch {}
+  #C14 = constructor-tearoff test::Class::redirect
+  #C15 = constructor-tearoff test::Class::redirect2
+  #C16 = true
+  #C17 = null
+}
diff --git a/pkg/front_end/testcases/dart2js/tear_off_patch/origin_lib.dart b/pkg/front_end/testcases/dart2js/tear_off_patch/origin_lib.dart
new file mode 100644
index 000000000000..c29cf6f2e642
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/tear_off_patch/origin_lib.dart
@@ -0,0 +1,19 @@
+// Copyright (c) 2022, 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.
+
+class Class<T> {
+  external Class({bool defaultValue: true, required T value});
+  external factory Class.fact({bool defaultValue: true, required T value});
+  external factory Class.redirect({bool defaultValue, required T value});
+  external factory Class.redirect2({bool defaultValue, required T value});
+}
+
+class ClassImpl<T> implements Class<T> {
+  ClassImpl({bool defaultValue: true, required T value});
+
+  external ClassImpl.patched({bool defaultValue: true, required T value});
+}
+
+typedef Alias<T extends num> = Class<T>;
+typedef AliasImpl<T extends num> = ClassImpl<T>;
diff --git a/pkg/front_end/testcases/dart2js/tear_off_patch/patch_lib.dart b/pkg/front_end/testcases/dart2js/tear_off_patch/patch_lib.dart
new file mode 100644
index 000000000000..77fdfb02e68f
--- /dev/null
+++ b/pkg/front_end/testcases/dart2js/tear_off_patch/patch_lib.dart
@@ -0,0 +1,33 @@
+// Copyright (c) 2022, 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.
+
+// ignore: import_internal_library
+import 'dart:_js_helper';
+
+@patch
+class Class<T> {
+  @patch
+  Class({bool defaultValue: true, required T value}) {
+    print('patch Class');
+  }
+
+  @patch
+  factory Class.fact({bool defaultValue: true, required T value}) =>
+      new ClassImpl<T>(defaultValue: defaultValue, value: value);
+
+  @patch
+  factory Class.redirect({bool defaultValue, required T value}) = ClassImpl<T>;
+
+  @patch
+  factory Class.redirect2({bool defaultValue, required T value}) =
+      ClassImpl<T>.patched;
+}
+
+@patch
+class ClassImpl<T> implements Class<T> {
+  @patch
+  ClassImpl.patched({bool defaultValue: true, required T value}) {
+    print('patch ClassImpl');
+  }
+}
diff --git a/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.strong.expect b/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.strong.expect
index 3eaf93271eb8..af740373d134 100644
--- a/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.strong.expect
+++ b/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.strong.expect
@@ -24,12 +24,12 @@ class Class extends core::Object {
   @#C1
   static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact({core::bool defaultValue = #C3}) → test::Class
     return new test::Class::_internal(defaultValue: defaultValue);
-  static method _#fact#tearOff({core::bool defaultValue = #C3}) → test::Class
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#fact#tearOff({core::bool defaultValue = #C3}) → test::Class
     return test::Class::fact(defaultValue: defaultValue);
   @#C1
   static factory /* from org-dartlang-testcase:///patch_lib.dart */ constFact({core::bool defaultValue = #C3}) → test::Class
     return throw "unsupported";
-  static method _#constFact#tearOff({core::bool defaultValue = #C3}) → test::Class
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#constFact#tearOff({core::bool defaultValue = #C3}) → test::Class
     return test::Class::constFact(defaultValue: defaultValue);
   static method /* from org-dartlang-testcase:///patch_lib.dart */ _#_internal#tearOff({core::bool defaultValue = #C2}) → test::Class
     return new test::Class::_internal(defaultValue: defaultValue);
diff --git a/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.strong.transformed.expect b/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.strong.transformed.expect
index 3eaf93271eb8..af740373d134 100644
--- a/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.strong.transformed.expect
@@ -24,12 +24,12 @@ class Class extends core::Object {
   @#C1
   static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact({core::bool defaultValue = #C3}) → test::Class
     return new test::Class::_internal(defaultValue: defaultValue);
-  static method _#fact#tearOff({core::bool defaultValue = #C3}) → test::Class
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#fact#tearOff({core::bool defaultValue = #C3}) → test::Class
     return test::Class::fact(defaultValue: defaultValue);
   @#C1
   static factory /* from org-dartlang-testcase:///patch_lib.dart */ constFact({core::bool defaultValue = #C3}) → test::Class
     return throw "unsupported";
-  static method _#constFact#tearOff({core::bool defaultValue = #C3}) → test::Class
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#constFact#tearOff({core::bool defaultValue = #C3}) → test::Class
     return test::Class::constFact(defaultValue: defaultValue);
   static method /* from org-dartlang-testcase:///patch_lib.dart */ _#_internal#tearOff({core::bool defaultValue = #C2}) → test::Class
     return new test::Class::_internal(defaultValue: defaultValue);
diff --git a/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.weak.expect b/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.weak.expect
index 3eaf93271eb8..af740373d134 100644
--- a/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.weak.expect
+++ b/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.weak.expect
@@ -24,12 +24,12 @@ class Class extends core::Object {
   @#C1
   static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact({core::bool defaultValue = #C3}) → test::Class
     return new test::Class::_internal(defaultValue: defaultValue);
-  static method _#fact#tearOff({core::bool defaultValue = #C3}) → test::Class
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#fact#tearOff({core::bool defaultValue = #C3}) → test::Class
     return test::Class::fact(defaultValue: defaultValue);
   @#C1
   static factory /* from org-dartlang-testcase:///patch_lib.dart */ constFact({core::bool defaultValue = #C3}) → test::Class
     return throw "unsupported";
-  static method _#constFact#tearOff({core::bool defaultValue = #C3}) → test::Class
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#constFact#tearOff({core::bool defaultValue = #C3}) → test::Class
     return test::Class::constFact(defaultValue: defaultValue);
   static method /* from org-dartlang-testcase:///patch_lib.dart */ _#_internal#tearOff({core::bool defaultValue = #C2}) → test::Class
     return new test::Class::_internal(defaultValue: defaultValue);
diff --git a/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.weak.modular.expect b/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.weak.modular.expect
index 3eaf93271eb8..af740373d134 100644
--- a/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.weak.modular.expect
+++ b/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.weak.modular.expect
@@ -24,12 +24,12 @@ class Class extends core::Object {
   @#C1
   static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact({core::bool defaultValue = #C3}) → test::Class
     return new test::Class::_internal(defaultValue: defaultValue);
-  static method _#fact#tearOff({core::bool defaultValue = #C3}) → test::Class
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#fact#tearOff({core::bool defaultValue = #C3}) → test::Class
     return test::Class::fact(defaultValue: defaultValue);
   @#C1
   static factory /* from org-dartlang-testcase:///patch_lib.dart */ constFact({core::bool defaultValue = #C3}) → test::Class
     return throw "unsupported";
-  static method _#constFact#tearOff({core::bool defaultValue = #C3}) → test::Class
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#constFact#tearOff({core::bool defaultValue = #C3}) → test::Class
     return test::Class::constFact(defaultValue: defaultValue);
   static method /* from org-dartlang-testcase:///patch_lib.dart */ _#_internal#tearOff({core::bool defaultValue = #C2}) → test::Class
     return new test::Class::_internal(defaultValue: defaultValue);
diff --git a/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.weak.transformed.expect b/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.weak.transformed.expect
index 3eaf93271eb8..af740373d134 100644
--- a/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/dartdevc/factory_patch/main.dart.weak.transformed.expect
@@ -24,12 +24,12 @@ class Class extends core::Object {
   @#C1
   static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact({core::bool defaultValue = #C3}) → test::Class
     return new test::Class::_internal(defaultValue: defaultValue);
-  static method _#fact#tearOff({core::bool defaultValue = #C3}) → test::Class
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#fact#tearOff({core::bool defaultValue = #C3}) → test::Class
     return test::Class::fact(defaultValue: defaultValue);
   @#C1
   static factory /* from org-dartlang-testcase:///patch_lib.dart */ constFact({core::bool defaultValue = #C3}) → test::Class
     return throw "unsupported";
-  static method _#constFact#tearOff({core::bool defaultValue = #C3}) → test::Class
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#constFact#tearOff({core::bool defaultValue = #C3}) → test::Class
     return test::Class::constFact(defaultValue: defaultValue);
   static method /* from org-dartlang-testcase:///patch_lib.dart */ _#_internal#tearOff({core::bool defaultValue = #C2}) → test::Class
     return new test::Class::_internal(defaultValue: defaultValue);
diff --git a/pkg/front_end/testcases/general/tear_off_patch/libraries.json b/pkg/front_end/testcases/general/tear_off_patch/libraries.json
new file mode 100644
index 000000000000..154c73c30b2b
--- /dev/null
+++ b/pkg/front_end/testcases/general/tear_off_patch/libraries.json
@@ -0,0 +1,12 @@
+{
+  "none": {
+    "libraries": {
+      "test": {
+        "patches": [
+          "patch_lib.dart"
+        ],
+        "uri": "origin_lib.dart"
+      }
+    }
+  }
+}
diff --git a/pkg/front_end/testcases/general/tear_off_patch/main.dart b/pkg/front_end/testcases/general/tear_off_patch/main.dart
new file mode 100644
index 000000000000..676f68ab0f39
--- /dev/null
+++ b/pkg/front_end/testcases/general/tear_off_patch/main.dart
@@ -0,0 +1,20 @@
+// Copyright (c) 2022, 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.
+
+import 'dart:test';
+
+main() {
+  Class.new;
+  Class.fact;
+  Class.redirect;
+  Class.redirect2;
+  ClassImpl.new;
+  ClassImpl.patched;
+  Alias.new;
+  Alias.fact;
+  Alias.redirect;
+  Alias.redirect2;
+  AliasImpl.new;
+  AliasImpl.patched;
+}
diff --git a/pkg/front_end/testcases/general/tear_off_patch/main.dart.strong.expect b/pkg/front_end/testcases/general/tear_off_patch/main.dart.strong.expect
new file mode 100644
index 000000000000..3ba9f8689061
--- /dev/null
+++ b/pkg/front_end/testcases/general/tear_off_patch/main.dart.strong.expect
@@ -0,0 +1,104 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  #C1;
+  #C2;
+  #C3;
+  #C4;
+  #C5;
+  #C6;
+  #C7;
+  #C8;
+  #C9;
+  #C10;
+  #C11;
+  #C12;
+}
+
+library /*isNonNullableByDefault*/;
+import self as test;
+import "dart:core" as core;
+import "dart:_js_helper" as _js;
+
+import "dart:_js_helper";
+
+typedef Alias<T extends core::num> = test::Class<T>;
+typedef AliasImpl<T extends core::num> = test::ClassImpl<T>;
+@#C13
+class Class<T extends core::Object? = dynamic> extends core::Object {
+  static final field dynamic _redirecting# = <dynamic>[#C14, #C15]/*isLegacy*/;
+  @#C13
+  constructor •({core::bool defaultValue = #C16, required test::Class::T% value = #C17}) → test::Class<test::Class::T%>
+    : super core::Object::•() {
+    core::print("patch Class");
+  }
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#new#tearOff::T% value = #C17}) → test::Class<test::Class::_#new#tearOff::T%>
+    return new test::Class::•<test::Class::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::fact::T% value = #C17}) → test::Class<test::Class::fact::T%>
+    return new test::ClassImpl::•<test::Class::fact::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#fact#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#fact#tearOff::T% value = #C17}) → test::Class<test::Class::_#fact#tearOff::T%>
+    return test::Class::fact<test::Class::_#fact#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect::T% value = #C17}) → test::Class<test::Class::redirect::T%>
+    return new test::ClassImpl::•<test::Class::redirect::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect#tearOff::T%>
+    return new test::ClassImpl::•<test::Class::_#redirect#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect2<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect2::T% value = #C17}) → test::Class<test::Class::redirect2::T%>
+    return new test::ClassImpl::patched<test::Class::redirect2::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect2#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect2#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect2#tearOff::T%>
+    return new test::ClassImpl::patched<test::Class::_#redirect2#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+@#C13
+class ClassImpl<T extends core::Object? = dynamic> extends core::Object implements test::Class<test::ClassImpl::T%> {
+  constructor •({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•()
+    ;
+  @#C13
+  constructor patched({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•() {
+    core::print("patch ClassImpl");
+  }
+  static method _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#new#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#new#tearOff::T%>
+    return new test::ClassImpl::•<test::ClassImpl::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#patched#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#patched#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#patched#tearOff::T%>
+    return new test::ClassImpl::patched<test::ClassImpl::_#patched#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+static method _#Alias#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#new#tearOff::T value = #C17}) → test::Class<test::_#Alias#new#tearOff::T>
+  return new test::Class::•<test::_#Alias#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#fact#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#fact#tearOff::T value = #C17}) → test::Class<test::_#Alias#fact#tearOff::T>
+  return test::Class::fact<test::_#Alias#fact#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect#tearOff::T>
+  return test::Class::_#redirect#tearOff<test::_#Alias#redirect#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect2#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect2#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect2#tearOff::T>
+  return test::Class::_#redirect2#tearOff<test::_#Alias#redirect2#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#new#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#new#tearOff::T>
+  return new test::ClassImpl::•<test::_#AliasImpl#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#patched#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#patched#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#patched#tearOff::T>
+  return new test::ClassImpl::patched<test::_#AliasImpl#patched#tearOff::T>(defaultValue: defaultValue, value: value);
+
+constants  {
+  #C1 = static-tearoff test::Class::_#new#tearOff
+  #C2 = static-tearoff test::Class::_#fact#tearOff
+  #C3 = static-tearoff test::Class::_#redirect#tearOff
+  #C4 = static-tearoff test::Class::_#redirect2#tearOff
+  #C5 = static-tearoff test::ClassImpl::_#new#tearOff
+  #C6 = static-tearoff test::ClassImpl::_#patched#tearOff
+  #C7 = static-tearoff test::_#Alias#new#tearOff
+  #C8 = static-tearoff test::_#Alias#fact#tearOff
+  #C9 = static-tearoff test::_#Alias#redirect#tearOff
+  #C10 = static-tearoff test::_#Alias#redirect2#tearOff
+  #C11 = static-tearoff test::_#AliasImpl#new#tearOff
+  #C12 = static-tearoff test::_#AliasImpl#patched#tearOff
+  #C13 = _js::_Patch {}
+  #C14 = constructor-tearoff test::Class::redirect
+  #C15 = constructor-tearoff test::Class::redirect2
+  #C16 = true
+  #C17 = null
+}
diff --git a/pkg/front_end/testcases/general/tear_off_patch/main.dart.strong.transformed.expect b/pkg/front_end/testcases/general/tear_off_patch/main.dart.strong.transformed.expect
new file mode 100644
index 000000000000..3ba9f8689061
--- /dev/null
+++ b/pkg/front_end/testcases/general/tear_off_patch/main.dart.strong.transformed.expect
@@ -0,0 +1,104 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  #C1;
+  #C2;
+  #C3;
+  #C4;
+  #C5;
+  #C6;
+  #C7;
+  #C8;
+  #C9;
+  #C10;
+  #C11;
+  #C12;
+}
+
+library /*isNonNullableByDefault*/;
+import self as test;
+import "dart:core" as core;
+import "dart:_js_helper" as _js;
+
+import "dart:_js_helper";
+
+typedef Alias<T extends core::num> = test::Class<T>;
+typedef AliasImpl<T extends core::num> = test::ClassImpl<T>;
+@#C13
+class Class<T extends core::Object? = dynamic> extends core::Object {
+  static final field dynamic _redirecting# = <dynamic>[#C14, #C15]/*isLegacy*/;
+  @#C13
+  constructor •({core::bool defaultValue = #C16, required test::Class::T% value = #C17}) → test::Class<test::Class::T%>
+    : super core::Object::•() {
+    core::print("patch Class");
+  }
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#new#tearOff::T% value = #C17}) → test::Class<test::Class::_#new#tearOff::T%>
+    return new test::Class::•<test::Class::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::fact::T% value = #C17}) → test::Class<test::Class::fact::T%>
+    return new test::ClassImpl::•<test::Class::fact::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#fact#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#fact#tearOff::T% value = #C17}) → test::Class<test::Class::_#fact#tearOff::T%>
+    return test::Class::fact<test::Class::_#fact#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect::T% value = #C17}) → test::Class<test::Class::redirect::T%>
+    return new test::ClassImpl::•<test::Class::redirect::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect#tearOff::T%>
+    return new test::ClassImpl::•<test::Class::_#redirect#tearOff::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect2<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect2::T% value = #C17}) → test::Class<test::Class::redirect2::T%>
+    return new test::ClassImpl::patched<test::Class::redirect2::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#redirect2#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::_#redirect2#tearOff::T% value = #C17}) → test::Class<test::Class::_#redirect2#tearOff::T%>
+    return new test::ClassImpl::patched<test::Class::_#redirect2#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+@#C13
+class ClassImpl<T extends core::Object? = dynamic> extends core::Object implements test::Class<test::ClassImpl::T%> {
+  constructor •({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•()
+    ;
+  @#C13
+  constructor patched({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•() {
+    core::print("patch ClassImpl");
+  }
+  static method _#new#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#new#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#new#tearOff::T%>
+    return new test::ClassImpl::•<test::ClassImpl::_#new#tearOff::T%>(defaultValue: defaultValue, value: value);
+  static method /* from org-dartlang-testcase:///patch_lib.dart */ _#patched#tearOff<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::ClassImpl::_#patched#tearOff::T% value = #C17}) → test::ClassImpl<test::ClassImpl::_#patched#tearOff::T%>
+    return new test::ClassImpl::patched<test::ClassImpl::_#patched#tearOff::T%>(defaultValue: defaultValue, value: value);
+}
+static method _#Alias#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#new#tearOff::T value = #C17}) → test::Class<test::_#Alias#new#tearOff::T>
+  return new test::Class::•<test::_#Alias#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#fact#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#fact#tearOff::T value = #C17}) → test::Class<test::_#Alias#fact#tearOff::T>
+  return test::Class::fact<test::_#Alias#fact#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect#tearOff::T>
+  return test::Class::_#redirect#tearOff<test::_#Alias#redirect#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect2#tearOff<T extends core::num>({core::bool defaultValue = #C17, required test::_#Alias#redirect2#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect2#tearOff::T>
+  return test::Class::_#redirect2#tearOff<test::_#Alias#redirect2#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#new#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#new#tearOff::T>
+  return new test::ClassImpl::•<test::_#AliasImpl#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#patched#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#patched#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#patched#tearOff::T>
+  return new test::ClassImpl::patched<test::_#AliasImpl#patched#tearOff::T>(defaultValue: defaultValue, value: value);
+
+constants  {
+  #C1 = static-tearoff test::Class::_#new#tearOff
+  #C2 = static-tearoff test::Class::_#fact#tearOff
+  #C3 = static-tearoff test::Class::_#redirect#tearOff
+  #C4 = static-tearoff test::Class::_#redirect2#tearOff
+  #C5 = static-tearoff test::ClassImpl::_#new#tearOff
+  #C6 = static-tearoff test::ClassImpl::_#patched#tearOff
+  #C7 = static-tearoff test::_#Alias#new#tearOff
+  #C8 = static-tearoff test::_#Alias#fact#tearOff
+  #C9 = static-tearoff test::_#Alias#redirect#tearOff
+  #C10 = static-tearoff test::_#Alias#redirect2#tearOff
+  #C11 = static-tearoff test::_#AliasImpl#new#tearOff
+  #C12 = static-tearoff test::_#AliasImpl#patched#tearOff
+  #C13 = _js::_Patch {}
+  #C14 = constructor-tearoff test::Class::redirect
+  #C15 = constructor-tearoff test::Class::redirect2
+  #C16 = true
+  #C17 = null
+}
diff --git a/pkg/front_end/testcases/general/tear_off_patch/main.dart.textual_outline.expect b/pkg/front_end/testcases/general/tear_off_patch/main.dart.textual_outline.expect
new file mode 100644
index 000000000000..3c9c90e9437e
--- /dev/null
+++ b/pkg/front_end/testcases/general/tear_off_patch/main.dart.textual_outline.expect
@@ -0,0 +1,3 @@
+import 'dart:test';
+
+main() {}
diff --git a/pkg/front_end/testcases/general/tear_off_patch/main.dart.textual_outline_modelled.expect b/pkg/front_end/testcases/general/tear_off_patch/main.dart.textual_outline_modelled.expect
new file mode 100644
index 000000000000..3c9c90e9437e
--- /dev/null
+++ b/pkg/front_end/testcases/general/tear_off_patch/main.dart.textual_outline_modelled.expect
@@ -0,0 +1,3 @@
+import 'dart:test';
+
+main() {}
diff --git a/pkg/front_end/testcases/general/tear_off_patch/main.dart.weak.expect b/pkg/front_end/testcases/general/tear_off_patch/main.dart.weak.expect
new file mode 100644
index 000000000000..7663f6b06ab6
--- /dev/null
+++ b/pkg/front_end/testcases/general/tear_off_patch/main.dart.weak.expect
@@ -0,0 +1,92 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  #C1;
+  #C2;
+  #C3;
+  #C4;
+  #C5;
+  #C6;
+  #C7;
+  #C8;
+  #C9;
+  #C10;
+  #C11;
+  #C12;
+}
+
+library /*isNonNullableByDefault*/;
+import self as test;
+import "dart:core" as core;
+import "dart:_internal" as _in;
+
+import "dart:_internal";
+
+typedef Alias<T extends core::num> = test::Class<T>;
+typedef AliasImpl<T extends core::num> = test::ClassImpl<T>;
+@#C13
+class Class<T extends core::Object? = dynamic> extends core::Object {
+  static final field dynamic _redirecting# = <dynamic>[#C14, #C15]/*isLegacy*/;
+  @#C13
+  constructor •({core::bool defaultValue = #C16, required test::Class::T% value = #C17}) → test::Class<test::Class::T%>
+    : super core::Object::•() {
+    core::print("patch Class");
+  }
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::fact::T% value = #C17}) → test::Class<test::Class::fact::T%>
+    return new test::ClassImpl::•<test::Class::fact::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect::T% value = #C17}) → test::Class<test::Class::redirect::T%>
+    return new test::ClassImpl::•<test::Class::redirect::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect2<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect2::T% value = #C17}) → test::Class<test::Class::redirect2::T%>
+    return new test::ClassImpl::patched<test::Class::redirect2::T%>(defaultValue: defaultValue, value: value);
+}
+@#C13
+class ClassImpl<T extends core::Object? = dynamic> extends core::Object implements test::Class<test::ClassImpl::T%> {
+  constructor •({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•()
+    ;
+  @#C13
+  constructor patched({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•() {
+    core::print("patch ClassImpl");
+  }
+}
+static method _#Alias#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#new#tearOff::T value = #C17}) → test::Class<test::_#Alias#new#tearOff::T>
+  return new test::Class::•<test::_#Alias#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#fact#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#fact#tearOff::T value = #C17}) → test::Class<test::_#Alias#fact#tearOff::T>
+  return test::Class::fact<test::_#Alias#fact#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#redirect#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect#tearOff::T>
+  return test::Class::redirect<test::_#Alias#redirect#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect2#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#redirect2#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect2#tearOff::T>
+  return test::Class::redirect2<test::_#Alias#redirect2#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#new#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#new#tearOff::T>
+  return new test::ClassImpl::•<test::_#AliasImpl#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#patched#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#patched#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#patched#tearOff::T>
+  return new test::ClassImpl::patched<test::_#AliasImpl#patched#tearOff::T>(defaultValue: defaultValue, value: value);
+
+constants  {
+  #C1 = constructor-tearoff test::Class::•
+  #C2 = constructor-tearoff test::Class::fact
+  #C3 = redirecting-factory-tearoff test::Class::redirect
+  #C4 = redirecting-factory-tearoff test::Class::redirect2
+  #C5 = constructor-tearoff test::ClassImpl::•
+  #C6 = constructor-tearoff test::ClassImpl::patched
+  #C7 = static-tearoff test::_#Alias#new#tearOff
+  #C8 = static-tearoff test::_#Alias#fact#tearOff
+  #C9 = static-tearoff test::_#Alias#redirect#tearOff
+  #C10 = static-tearoff test::_#Alias#redirect2#tearOff
+  #C11 = static-tearoff test::_#AliasImpl#new#tearOff
+  #C12 = static-tearoff test::_#AliasImpl#patched#tearOff
+  #C13 = _in::_Patch {}
+  #C14 = constructor-tearoff test::Class::redirect
+  #C15 = constructor-tearoff test::Class::redirect2
+  #C16 = true
+  #C17 = null
+}
diff --git a/pkg/front_end/testcases/general/tear_off_patch/main.dart.weak.modular.expect b/pkg/front_end/testcases/general/tear_off_patch/main.dart.weak.modular.expect
new file mode 100644
index 000000000000..7663f6b06ab6
--- /dev/null
+++ b/pkg/front_end/testcases/general/tear_off_patch/main.dart.weak.modular.expect
@@ -0,0 +1,92 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  #C1;
+  #C2;
+  #C3;
+  #C4;
+  #C5;
+  #C6;
+  #C7;
+  #C8;
+  #C9;
+  #C10;
+  #C11;
+  #C12;
+}
+
+library /*isNonNullableByDefault*/;
+import self as test;
+import "dart:core" as core;
+import "dart:_internal" as _in;
+
+import "dart:_internal";
+
+typedef Alias<T extends core::num> = test::Class<T>;
+typedef AliasImpl<T extends core::num> = test::ClassImpl<T>;
+@#C13
+class Class<T extends core::Object? = dynamic> extends core::Object {
+  static final field dynamic _redirecting# = <dynamic>[#C14, #C15]/*isLegacy*/;
+  @#C13
+  constructor •({core::bool defaultValue = #C16, required test::Class::T% value = #C17}) → test::Class<test::Class::T%>
+    : super core::Object::•() {
+    core::print("patch Class");
+  }
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::fact::T% value = #C17}) → test::Class<test::Class::fact::T%>
+    return new test::ClassImpl::•<test::Class::fact::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect::T% value = #C17}) → test::Class<test::Class::redirect::T%>
+    return new test::ClassImpl::•<test::Class::redirect::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect2<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect2::T% value = #C17}) → test::Class<test::Class::redirect2::T%>
+    return new test::ClassImpl::patched<test::Class::redirect2::T%>(defaultValue: defaultValue, value: value);
+}
+@#C13
+class ClassImpl<T extends core::Object? = dynamic> extends core::Object implements test::Class<test::ClassImpl::T%> {
+  constructor •({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•()
+    ;
+  @#C13
+  constructor patched({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•() {
+    core::print("patch ClassImpl");
+  }
+}
+static method _#Alias#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#new#tearOff::T value = #C17}) → test::Class<test::_#Alias#new#tearOff::T>
+  return new test::Class::•<test::_#Alias#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#fact#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#fact#tearOff::T value = #C17}) → test::Class<test::_#Alias#fact#tearOff::T>
+  return test::Class::fact<test::_#Alias#fact#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#redirect#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect#tearOff::T>
+  return test::Class::redirect<test::_#Alias#redirect#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect2#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#redirect2#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect2#tearOff::T>
+  return test::Class::redirect2<test::_#Alias#redirect2#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#new#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#new#tearOff::T>
+  return new test::ClassImpl::•<test::_#AliasImpl#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#patched#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#patched#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#patched#tearOff::T>
+  return new test::ClassImpl::patched<test::_#AliasImpl#patched#tearOff::T>(defaultValue: defaultValue, value: value);
+
+constants  {
+  #C1 = constructor-tearoff test::Class::•
+  #C2 = constructor-tearoff test::Class::fact
+  #C3 = redirecting-factory-tearoff test::Class::redirect
+  #C4 = redirecting-factory-tearoff test::Class::redirect2
+  #C5 = constructor-tearoff test::ClassImpl::•
+  #C6 = constructor-tearoff test::ClassImpl::patched
+  #C7 = static-tearoff test::_#Alias#new#tearOff
+  #C8 = static-tearoff test::_#Alias#fact#tearOff
+  #C9 = static-tearoff test::_#Alias#redirect#tearOff
+  #C10 = static-tearoff test::_#Alias#redirect2#tearOff
+  #C11 = static-tearoff test::_#AliasImpl#new#tearOff
+  #C12 = static-tearoff test::_#AliasImpl#patched#tearOff
+  #C13 = _in::_Patch {}
+  #C14 = constructor-tearoff test::Class::redirect
+  #C15 = constructor-tearoff test::Class::redirect2
+  #C16 = true
+  #C17 = null
+}
diff --git a/pkg/front_end/testcases/general/tear_off_patch/main.dart.weak.outline.expect b/pkg/front_end/testcases/general/tear_off_patch/main.dart.weak.outline.expect
new file mode 100644
index 000000000000..40d29d32f89f
--- /dev/null
+++ b/pkg/front_end/testcases/general/tear_off_patch/main.dart.weak.outline.expect
@@ -0,0 +1,65 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+import "dart:test";
+
+static method main() → dynamic
+  ;
+
+library /*isNonNullableByDefault*/;
+import self as self2;
+import "dart:core" as core;
+import "dart:_internal" as _in;
+
+import "dart:_internal";
+
+typedef Alias<T extends core::num> = self2::Class<T>;
+typedef AliasImpl<T extends core::num> = self2::ClassImpl<T>;
+@_in::patch
+class Class<T extends core::Object? = dynamic> extends core::Object {
+  static final field dynamic _redirecting# = <dynamic>[self2::Class::redirect, self2::Class::redirect2]/*isLegacy*/;
+  @_in::patch
+  external constructor •({core::bool defaultValue = true, required self2::Class::T% value = null}) → self2::Class<self2::Class::T%>
+    ;
+  @_in::patch
+  external static factory fact<T extends core::Object? = dynamic>({has-declared-initializer core::bool defaultValue, required self2::Class::fact::T% value}) → self2::Class<self2::Class::fact::T%>;
+  @_in::patch
+  external static factory redirect<T extends core::Object? = dynamic>({core::bool defaultValue, required self2::Class::redirect::T% value}) → self2::Class<self2::Class::redirect::T%>
+    return new self2::ClassImpl::•<self2::Class::redirect::T%>(defaultValue: defaultValue, value: value);
+  @_in::patch
+  external static factory redirect2<T extends core::Object? = dynamic>({core::bool defaultValue, required self2::Class::redirect2::T% value}) → self2::Class<self2::Class::redirect2::T%>
+    return new self2::ClassImpl::patched<self2::Class::redirect2::T%>(defaultValue: defaultValue, value: value);
+}
+@_in::patch
+class ClassImpl<T extends core::Object? = dynamic> extends core::Object implements self2::Class<self2::ClassImpl::T%> {
+  constructor •({core::bool defaultValue = true, required self2::ClassImpl::T% value = null}) → self2::ClassImpl<self2::ClassImpl::T%>
+    ;
+  @_in::patch
+  external constructor patched({core::bool defaultValue = true, required self2::ClassImpl::T% value = null}) → self2::ClassImpl<self2::ClassImpl::T%>
+    ;
+}
+static method _#Alias#new#tearOff<T extends core::num>({has-declared-initializer core::bool defaultValue, required self2::_#Alias#new#tearOff::T value}) → self2::Class<self2::_#Alias#new#tearOff::T>
+  return new self2::Class::•<self2::_#Alias#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#fact#tearOff<T extends core::num>({has-declared-initializer core::bool defaultValue, required self2::_#Alias#fact#tearOff::T value}) → self2::Class<self2::_#Alias#fact#tearOff::T>
+  return self2::Class::fact<self2::_#Alias#fact#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect#tearOff<T extends core::num>({core::bool defaultValue, required self2::_#Alias#redirect#tearOff::T value}) → self2::Class<self2::_#Alias#redirect#tearOff::T>
+  return self2::Class::redirect<self2::_#Alias#redirect#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect2#tearOff<T extends core::num>({core::bool defaultValue, required self2::_#Alias#redirect2#tearOff::T value}) → self2::Class<self2::_#Alias#redirect2#tearOff::T>
+  return self2::Class::redirect2<self2::_#Alias#redirect2#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#new#tearOff<T extends core::num>({has-declared-initializer core::bool defaultValue, required self2::_#AliasImpl#new#tearOff::T value}) → self2::ClassImpl<self2::_#AliasImpl#new#tearOff::T>
+  return new self2::ClassImpl::•<self2::_#AliasImpl#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#patched#tearOff<T extends core::num>({has-declared-initializer core::bool defaultValue, required self2::_#AliasImpl#patched#tearOff::T value}) → self2::ClassImpl<self2::_#AliasImpl#patched#tearOff::T>
+  return new self2::ClassImpl::patched<self2::_#AliasImpl#patched#tearOff::T>(defaultValue: defaultValue, value: value);
+
+
+Extra constant evaluation status:
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:6:46 -> InstanceConstant(const _Patch{})
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:7:9 -> InstanceConstant(const _Patch{})
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:8:28 -> InstanceConstant(const _Patch{})
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:12:21 -> InstanceConstant(const _Patch{})
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:15:11 -> InstanceConstant(const _Patch{})
+Evaluated: ConstructorTearOff @ org-dartlang-testcase:///origin_lib.dart:5:7 -> ConstructorTearOffConstant(Class.redirect)
+Evaluated: ConstructorTearOff @ org-dartlang-testcase:///origin_lib.dart:5:7 -> ConstructorTearOffConstant(Class.redirect2)
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:18:38 -> InstanceConstant(const _Patch{})
+Evaluated: StaticGet @ org-dartlang-testcase:///origin_lib.dart:19:47 -> InstanceConstant(const _Patch{})
+Extra constant evaluation: evaluated: 34, effectively constant: 9
diff --git a/pkg/front_end/testcases/general/tear_off_patch/main.dart.weak.transformed.expect b/pkg/front_end/testcases/general/tear_off_patch/main.dart.weak.transformed.expect
new file mode 100644
index 000000000000..7663f6b06ab6
--- /dev/null
+++ b/pkg/front_end/testcases/general/tear_off_patch/main.dart.weak.transformed.expect
@@ -0,0 +1,92 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:test" as test;
+
+import "dart:test";
+
+static method main() → dynamic {
+  #C1;
+  #C2;
+  #C3;
+  #C4;
+  #C5;
+  #C6;
+  #C7;
+  #C8;
+  #C9;
+  #C10;
+  #C11;
+  #C12;
+}
+
+library /*isNonNullableByDefault*/;
+import self as test;
+import "dart:core" as core;
+import "dart:_internal" as _in;
+
+import "dart:_internal";
+
+typedef Alias<T extends core::num> = test::Class<T>;
+typedef AliasImpl<T extends core::num> = test::ClassImpl<T>;
+@#C13
+class Class<T extends core::Object? = dynamic> extends core::Object {
+  static final field dynamic _redirecting# = <dynamic>[#C14, #C15]/*isLegacy*/;
+  @#C13
+  constructor •({core::bool defaultValue = #C16, required test::Class::T% value = #C17}) → test::Class<test::Class::T%>
+    : super core::Object::•() {
+    core::print("patch Class");
+  }
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ fact<T extends core::Object? = dynamic>({core::bool defaultValue = #C16, required test::Class::fact::T% value = #C17}) → test::Class<test::Class::fact::T%>
+    return new test::ClassImpl::•<test::Class::fact::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect::T% value = #C17}) → test::Class<test::Class::redirect::T%>
+    return new test::ClassImpl::•<test::Class::redirect::T%>(defaultValue: defaultValue, value: value);
+  @#C13
+  static factory /* from org-dartlang-testcase:///patch_lib.dart */ redirect2<T extends core::Object? = dynamic>({core::bool defaultValue = #C17, required test::Class::redirect2::T% value = #C17}) → test::Class<test::Class::redirect2::T%>
+    return new test::ClassImpl::patched<test::Class::redirect2::T%>(defaultValue: defaultValue, value: value);
+}
+@#C13
+class ClassImpl<T extends core::Object? = dynamic> extends core::Object implements test::Class<test::ClassImpl::T%> {
+  constructor •({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•()
+    ;
+  @#C13
+  constructor patched({core::bool defaultValue = #C16, required test::ClassImpl::T% value = #C17}) → test::ClassImpl<test::ClassImpl::T%>
+    : super core::Object::•() {
+    core::print("patch ClassImpl");
+  }
+}
+static method _#Alias#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#new#tearOff::T value = #C17}) → test::Class<test::_#Alias#new#tearOff::T>
+  return new test::Class::•<test::_#Alias#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#fact#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#fact#tearOff::T value = #C17}) → test::Class<test::_#Alias#fact#tearOff::T>
+  return test::Class::fact<test::_#Alias#fact#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#redirect#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect#tearOff::T>
+  return test::Class::redirect<test::_#Alias#redirect#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#Alias#redirect2#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#Alias#redirect2#tearOff::T value = #C17}) → test::Class<test::_#Alias#redirect2#tearOff::T>
+  return test::Class::redirect2<test::_#Alias#redirect2#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#new#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#new#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#new#tearOff::T>
+  return new test::ClassImpl::•<test::_#AliasImpl#new#tearOff::T>(defaultValue: defaultValue, value: value);
+static method _#AliasImpl#patched#tearOff<T extends core::num>({core::bool defaultValue = #C16, required test::_#AliasImpl#patched#tearOff::T value = #C17}) → test::ClassImpl<test::_#AliasImpl#patched#tearOff::T>
+  return new test::ClassImpl::patched<test::_#AliasImpl#patched#tearOff::T>(defaultValue: defaultValue, value: value);
+
+constants  {
+  #C1 = constructor-tearoff test::Class::•
+  #C2 = constructor-tearoff test::Class::fact
+  #C3 = redirecting-factory-tearoff test::Class::redirect
+  #C4 = redirecting-factory-tearoff test::Class::redirect2
+  #C5 = constructor-tearoff test::ClassImpl::•
+  #C6 = constructor-tearoff test::ClassImpl::patched
+  #C7 = static-tearoff test::_#Alias#new#tearOff
+  #C8 = static-tearoff test::_#Alias#fact#tearOff
+  #C9 = static-tearoff test::_#Alias#redirect#tearOff
+  #C10 = static-tearoff test::_#Alias#redirect2#tearOff
+  #C11 = static-tearoff test::_#AliasImpl#new#tearOff
+  #C12 = static-tearoff test::_#AliasImpl#patched#tearOff
+  #C13 = _in::_Patch {}
+  #C14 = constructor-tearoff test::Class::redirect
+  #C15 = constructor-tearoff test::Class::redirect2
+  #C16 = true
+  #C17 = null
+}
diff --git a/pkg/front_end/testcases/general/tear_off_patch/origin_lib.dart b/pkg/front_end/testcases/general/tear_off_patch/origin_lib.dart
new file mode 100644
index 000000000000..c29cf6f2e642
--- /dev/null
+++ b/pkg/front_end/testcases/general/tear_off_patch/origin_lib.dart
@@ -0,0 +1,19 @@
+// Copyright (c) 2022, 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.
+
+class Class<T> {
+  external Class({bool defaultValue: true, required T value});
+  external factory Class.fact({bool defaultValue: true, required T value});
+  external factory Class.redirect({bool defaultValue, required T value});
+  external factory Class.redirect2({bool defaultValue, required T value});
+}
+
+class ClassImpl<T> implements Class<T> {
+  ClassImpl({bool defaultValue: true, required T value});
+
+  external ClassImpl.patched({bool defaultValue: true, required T value});
+}
+
+typedef Alias<T extends num> = Class<T>;
+typedef AliasImpl<T extends num> = ClassImpl<T>;
diff --git a/pkg/front_end/testcases/general/tear_off_patch/patch_lib.dart b/pkg/front_end/testcases/general/tear_off_patch/patch_lib.dart
new file mode 100644
index 000000000000..7265272d4452
--- /dev/null
+++ b/pkg/front_end/testcases/general/tear_off_patch/patch_lib.dart
@@ -0,0 +1,33 @@
+// Copyright (c) 2022, 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.
+
+// ignore: import_internal_library
+import 'dart:_internal';
+
+@patch
+class Class<T> {
+  @patch
+  Class({bool defaultValue: true, required T value}) {
+    print('patch Class');
+  }
+
+  @patch
+  factory Class.fact({bool defaultValue: true, required T value}) =>
+      new ClassImpl<T>(defaultValue: defaultValue, value: value);
+
+  @patch
+  factory Class.redirect({bool defaultValue, required T value}) = ClassImpl<T>;
+
+  @patch
+  factory Class.redirect2({bool defaultValue, required T value}) =
+      ClassImpl<T>.patched;
+}
+
+@patch
+class ClassImpl<T> implements Class<T> {
+  @patch
+  ClassImpl.patched({bool defaultValue: true, required T value}) {
+    print('patch ClassImpl');
+  }
+}
diff --git a/tests/language/constructor/patch_tear_off_test.dart b/tests/language/constructor/patch_tear_off_test.dart
new file mode 100644
index 000000000000..632a208bd4ba
--- /dev/null
+++ b/tests/language/constructor/patch_tear_off_test.dart
@@ -0,0 +1,10 @@
+// Copyright (c) 2022, 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.
+
+// Regression test for https://github.com/dart-lang/sdk/issues/48776
+
+main() {
+  /// BigInt.from is a patched constructor.
+  BigInt.from;
+}