diff --git a/pkg/front_end/test/incremental_suite.dart b/pkg/front_end/test/incremental_suite.dart
index b801d37adb7..2479d56a2bc 100644
--- a/pkg/front_end/test/incremental_suite.dart
+++ b/pkg/front_end/test/incremental_suite.dart
@@ -1585,7 +1585,10 @@ class NewWorldTest {
             compiler.getFilteredInvalidatedImportUrisForTesting(invalidated);
         if (world.invalidate != null) {
           Expect.equals(
-              world.invalidate!.length, filteredInvalidated?.length ?? 0);
+              world.invalidate!.length,
+              filteredInvalidated?.length ?? 0,
+              "Unexpected invalidated files: ${filteredInvalidated}, "
+              "actual: ${world.invalidate}.");
           if (world.expectedInvalidatedUri != null) {
             Expect.setEquals(
                 world.expectedInvalidatedUri!.map((s) => base.resolve(s)),
diff --git a/pkg/front_end/testcases/incremental/flutter_widget_factory.yaml b/pkg/front_end/testcases/incremental/flutter_widget_factory.yaml
new file mode 100644
index 00000000000..c5a72f92bba
--- /dev/null
+++ b/pkg/front_end/testcases/incremental/flutter_widget_factory.yaml
@@ -0,0 +1,144 @@
+# 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.md file.
+
+type: newworld
+target: dartdevc
+trackWidgetCreation: true
+worlds:
+  - entry: main.dart
+    sources:
+      main.dart: |
+        import 'foo.dart';
+        Foo newFoo = new Foo();
+        var newFooFunction = Foo.new;
+        var newFooFunctionCall = newFooFunction();
+        Foo extensionFoo = null.foo();
+        var extensionFooFunction = null.foo;
+        var extensionFooFunctionCall = extensionFooFunction();
+        Foo extensionBar = null.bar();
+        Foo extensionBaz = null.baz();
+        Foo extensionBoz = null.boz();
+        Foo extensionConstFoo = null.constFoo();
+        Foo extensionGetterFoo = null.getterFoo;
+        var extensionSetterFoo = () => null.setterFoo = null;
+        Foo extensionOperatorFoo = -null;
+        Foo extensionStaticFoo = FooExtension.staticFoo();
+      foo.dart: |
+        import 'package:flutter/src/widgets/framework.dart';
+
+        const alias = widgetFactory;
+        const nullableAlias = false ? widgetFactory : null;
+        const nonNullableAlias = false ? widgetFactory : alias;
+
+        class Foo extends Widget {
+          factory Foo() => const Foo._();
+
+          const Foo._();
+        }
+
+        extension FooExtension on Object? {
+          @widgetFactory
+          Foo foo() => Foo._();
+
+          @alias
+          Foo bar() => Foo._();
+
+          @nullableAlias
+          Foo baz() => Foo._();
+
+          @nonNullableAlias
+          Foo boz() => Foo._();
+
+          @widgetFactory
+          Foo constFoo() => const Foo._();
+
+          @widgetFactory
+          Foo get getterFoo => new Foo._();
+
+          @widgetFactory
+          void set setterFoo(_) => new Foo._();
+
+          @widgetFactory
+          Foo operator -() => new Foo._();
+
+          @widgetFactory
+          static Foo staticFoo() => new Foo._();
+        }
+      flutter/lib/src/widgets/framework.dart: |
+        export 'widget_inspector.dart' show widgetFactory;
+
+        abstract class Bar {
+          const Bar();
+        }
+        abstract class Widget extends Bar {
+          const Widget();
+        }
+      flutter/lib/src/widgets/widget_inspector.dart: |
+        abstract class _HasCreationLocation {
+          _Location get _location;
+        }
+        /// A tuple with file, line, and column number, for displaying human-readable
+        /// file locations.
+        class _Location {
+          const _Location({
+            required this.file,
+            required this.line,
+            required this.column,
+            required this.name,
+            required this.parameterLocations,
+          });
+          /// File path of the location.
+          final String file;
+          /// 1-based line number.
+          final int line;
+          /// 1-based column number.
+          final int column;
+          /// Optional name of the parameter or function at this location.
+          final String name;
+          /// Optional locations of the parameters of the member at this location.
+          final List<_Location> parameterLocations;
+        }
+
+        class _WidgetFactory {
+          const _WidgetFactory();
+        }
+
+        const widgetFactory = _WidgetFactory();
+      .dart_tool/package_config.json: |
+        {
+          "configVersion": 2,
+          "packages": [
+            {
+              "name": "flutter",
+              "rootUri": "../flutter",
+              "packageUri": "lib/"
+            }
+          ]
+        }
+    expectedLibraryCount: 4
+
+  - entry: main.dart
+    worldType: updated
+    invalidate:
+      - main.dart
+    expectInitializeFromDill: false
+    sources:
+      main.dart: |
+        import 'foo.dart';
+        Foo extensionConstFoo = null.constFoo();
+        Foo newFoo = new Foo();
+        var newFooFunction = Foo.new;
+        var newFooFunctionCall = newFooFunction();
+        Foo extensionFoo = null.foo();
+        var extensionFooFunction = null.foo;
+        var extensionFooFunctionCall = extensionFooFunction();
+        Foo extensionBar = null.bar();
+        Foo extensionBaz = null.baz();
+        Foo extensionBoz = null.boz();
+        Foo extensionGetterFoo = null.getterFoo;
+        var extensionSetterFoo = () => null.setterFoo = null;
+        Foo extensionOperatorFoo = -null;
+        Foo extensionStaticFoo = FooExtension.staticFoo();
+    expectedLibraryCount: 4
+    advancedInvalidation: bodiesOnly
diff --git a/pkg/front_end/testcases/incremental/flutter_widget_factory.yaml.world.1.expect b/pkg/front_end/testcases/incremental/flutter_widget_factory.yaml.world.1.expect
new file mode 100644
index 00000000000..0f30faab532
--- /dev/null
+++ b/pkg/front_end/testcases/incremental/flutter_widget_factory.yaml.world.1.expect
@@ -0,0 +1,215 @@
+main = <No Member>;
+library from "package:flutter/src/widgets/framework.dart" as fra {
+additionalExports = (wid::widgetFactory)
+
+  export "package:flutter/src/widgets/widget_inspector.dart" show widgetFactory;
+
+  abstract class Bar extends dart.core::Object /*hasConstConstructor*/  {
+    const constructor •() → fra::Bar
+      : super dart.core::Object::•()
+      ;
+  }
+  abstract class Widget extends fra::Bar implements wid::_HasCreationLocation /*hasConstConstructor*/  {
+    final field wid::_Location? _location /*isLegacy*/;
+    const constructor •({wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → fra::Widget
+      : super fra::Bar::•(), fra::Widget::_location = $creationLocationd_0dea112b090073317d4
+      ;
+  }
+}
+library from "package:flutter/src/widgets/widget_inspector.dart" as wid {
+
+  abstract class _HasCreationLocation extends dart.core::Object {
+    synthetic constructor •() → wid::_HasCreationLocation
+      : super dart.core::Object::•()
+      ;
+    abstract get _location() → wid::_Location;
+  }
+  class _Location extends dart.core::Object /*hasConstConstructor*/  {
+    final field dart.core::String file;
+    final field dart.core::int line;
+    final field dart.core::int column;
+    final field dart.core::String name;
+    final field dart.core::List<wid::_Location> parameterLocations;
+    const constructor •({required dart.core::String file = #C1, required dart.core::int line = #C1, required dart.core::int column = #C1, required dart.core::String name = #C1, required dart.core::List<wid::_Location> parameterLocations = #C1}) → wid::_Location
+      : wid::_Location::file = file, wid::_Location::line = line, wid::_Location::column = column, wid::_Location::name = name, wid::_Location::parameterLocations = parameterLocations, super dart.core::Object::•()
+      ;
+    static method _#new#tearOff({required dart.core::String file = #C1, required dart.core::int line = #C1, required dart.core::int column = #C1, required dart.core::String name = #C1, required dart.core::List<wid::_Location> parameterLocations = #C1}) → wid::_Location
+      return new wid::_Location::•(file: file, line: line, column: column, name: name, parameterLocations: parameterLocations);
+  }
+  class _WidgetFactory extends dart.core::Object /*hasConstConstructor*/  {
+    const constructor •() → wid::_WidgetFactory
+      : super dart.core::Object::•()
+      ;
+    static method _#new#tearOff() → wid::_WidgetFactory
+      return new wid::_WidgetFactory::•();
+  }
+  static const field wid::_WidgetFactory widgetFactory = #C2;
+}
+library from "org-dartlang-test:///foo.dart" as foo {
+
+  import "package:flutter/src/widgets/framework.dart";
+
+  class Foo extends fra::Widget /*hasConstConstructor*/  {
+    const constructor _({wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+      : super fra::Widget::•($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4)
+      ;
+    static factory •({wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+      return #C8;
+    static method _#new#tearOff() → foo::Foo
+      return foo::Foo::•($creationLocationd_0dea112b090073317d4: #C10);
+    static method _#_#tearOff() → foo::Foo
+      return new foo::Foo::_($creationLocationd_0dea112b090073317d4: #C13);
+  }
+  extension FooExtension on dart.core::Object? {
+    method foo = foo::FooExtension|foo;
+    tearoff foo = foo::FooExtension|get#foo;
+    method bar = foo::FooExtension|bar;
+    tearoff bar = foo::FooExtension|get#bar;
+    method baz = foo::FooExtension|baz;
+    tearoff baz = foo::FooExtension|get#baz;
+    method boz = foo::FooExtension|boz;
+    tearoff boz = foo::FooExtension|get#boz;
+    method constFoo = foo::FooExtension|constFoo;
+    tearoff constFoo = foo::FooExtension|get#constFoo;
+    get getterFoo = foo::FooExtension|get#getterFoo;
+    operator unary- = foo::FooExtension|unary-;
+    static method staticFoo = foo::FooExtension|staticFoo;
+    set setterFoo = foo::FooExtension|set#setterFoo;
+  }
+  static const field wid::_WidgetFactory alias = #C2;
+  static const field wid::_WidgetFactory? nullableAlias = #C1;
+  static const field wid::_WidgetFactory nonNullableAlias = #C2;
+  @#C2
+  static method FooExtension|foo(lowered final dart.core::Object? #this, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#foo(lowered final dart.core::Object? #this) → () → foo::Foo
+    return () → foo::Foo => foo::FooExtension|foo(#this, $creationLocationd_0dea112b090073317d4: #C17);
+  @#C2
+  static method FooExtension|bar(lowered final dart.core::Object? #this, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#bar(lowered final dart.core::Object? #this) → () → foo::Foo
+    return () → foo::Foo => foo::FooExtension|bar(#this, $creationLocationd_0dea112b090073317d4: #C20);
+  @#C1
+  static method FooExtension|baz(lowered final dart.core::Object? #this) → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: #C23);
+  static method FooExtension|get#baz(lowered final dart.core::Object? #this) → () → foo::Foo
+    return () → foo::Foo => foo::FooExtension|baz(#this);
+  @#C2
+  static method FooExtension|boz(lowered final dart.core::Object? #this, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#boz(lowered final dart.core::Object? #this) → () → foo::Foo
+    return () → foo::Foo => foo::FooExtension|boz(#this, $creationLocationd_0dea112b090073317d4: #C26);
+  @#C2
+  static method FooExtension|constFoo(lowered final dart.core::Object? #this, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+    return #C29;
+  static method FooExtension|get#constFoo(lowered final dart.core::Object? #this) → () → foo::Foo
+    return () → foo::Foo => foo::FooExtension|constFoo(#this, $creationLocationd_0dea112b090073317d4: #C31);
+  @#C2
+  static method FooExtension|get#getterFoo(lowered final dart.core::Object? #this, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  @#C2
+  static method FooExtension|set#setterFoo(lowered final dart.core::Object? #this, dynamic _, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → void
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  @#C2
+  static method FooExtension|unary-(lowered final dart.core::Object? #this, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  @#C2
+  static method FooExtension|staticFoo() → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: #C34);
+}
+library from "org-dartlang-test:///main.dart" as main {
+
+  import "org-dartlang-test:///foo.dart";
+
+  static field foo::Foo newFoo = foo::Foo::•($creationLocationd_0dea112b090073317d4: #C37);
+  static field () → foo::Foo newFooFunction = #C38;
+  static field foo::Foo newFooFunctionCall = main::newFooFunction(){() → foo::Foo};
+  static field foo::Foo extensionFoo = foo::FooExtension|foo(null, $creationLocationd_0dea112b090073317d4: #C41);
+  static field () → foo::Foo extensionFooFunction = foo::FooExtension|get#foo(null);
+  static field foo::Foo extensionFooFunctionCall = main::extensionFooFunction(){() → foo::Foo};
+  static field foo::Foo extensionBar = foo::FooExtension|bar(null, $creationLocationd_0dea112b090073317d4: #C42);
+  static field foo::Foo extensionBaz = foo::FooExtension|baz(null);
+  static field foo::Foo extensionBoz = foo::FooExtension|boz(null, $creationLocationd_0dea112b090073317d4: #C43);
+  static field foo::Foo extensionConstFoo = foo::FooExtension|constFoo(null, $creationLocationd_0dea112b090073317d4: #C45);
+  static field foo::Foo extensionGetterFoo = foo::FooExtension|get#getterFoo(null, $creationLocationd_0dea112b090073317d4: #C49);
+  static field () → Null extensionSetterFoo = () → Null => let final has-declared-initializer Null #t1 = null in let final void #t2 = foo::FooExtension|set#setterFoo(null, #t1, $creationLocationd_0dea112b090073317d4: #C53) in #t1;
+  static field foo::Foo extensionOperatorFoo = foo::FooExtension|unary-(null, $creationLocationd_0dea112b090073317d4: #C57);
+  static field foo::Foo extensionStaticFoo = foo::FooExtension|staticFoo();
+}
+constants  {
+  #C1 = null
+  #C2 = wid::_WidgetFactory {}
+  #C3 = "org-dartlang-test:///foo.dart"
+  #C4 = 8.0
+  #C5 = 26.0
+  #C6 = "Foo"
+  #C7 = wid::_Location {file:#C3, line:#C4, column:#C5, name:#C6, parameterLocations:#C1}
+  #C8 = foo::Foo {_location:#C7}
+  #C9 = 11.0
+  #C10 = wid::_Location {file:#C3, line:#C4, column:#C9, name:#C6, parameterLocations:#C1}
+  #C11 = 10.0
+  #C12 = 9.0
+  #C13 = wid::_Location {file:#C3, line:#C11, column:#C12, name:#C6, parameterLocations:#C1}
+  #C14 = 15.0
+  #C15 = 7.0
+  #C16 = "FooExtension|foo"
+  #C17 = wid::_Location {file:#C3, line:#C14, column:#C15, name:#C16, parameterLocations:#C1}
+  #C18 = 18.0
+  #C19 = "FooExtension|bar"
+  #C20 = wid::_Location {file:#C3, line:#C18, column:#C15, name:#C19, parameterLocations:#C1}
+  #C21 = 21.0
+  #C22 = 20.0
+  #C23 = wid::_Location {file:#C3, line:#C21, column:#C22, name:#C6, parameterLocations:#C1}
+  #C24 = 24.0
+  #C25 = "FooExtension|boz"
+  #C26 = wid::_Location {file:#C3, line:#C24, column:#C15, name:#C25, parameterLocations:#C1}
+  #C27 = 27.0
+  #C28 = wid::_Location {file:#C3, line:#C27, column:#C27, name:#C6, parameterLocations:#C1}
+  #C29 = foo::Foo {_location:#C28}
+  #C30 = "FooExtension|constFoo"
+  #C31 = wid::_Location {file:#C3, line:#C27, column:#C15, name:#C30, parameterLocations:#C1}
+  #C32 = 39.0
+  #C33 = 33.0
+  #C34 = wid::_Location {file:#C3, line:#C32, column:#C33, name:#C6, parameterLocations:#C1}
+  #C35 = "org-dartlang-test:///main.dart"
+  #C36 = 2.0
+  #C37 = wid::_Location {file:#C35, line:#C36, column:#C18, name:#C6, parameterLocations:#C1}
+  #C38 = static-tearoff foo::Foo::_#new#tearOff
+  #C39 = 5.0
+  #C40 = 25.0
+  #C41 = wid::_Location {file:#C35, line:#C39, column:#C40, name:#C16, parameterLocations:#C1}
+  #C42 = wid::_Location {file:#C35, line:#C4, column:#C40, name:#C19, parameterLocations:#C1}
+  #C43 = wid::_Location {file:#C35, line:#C11, column:#C40, name:#C25, parameterLocations:#C1}
+  #C44 = 30.0
+  #C45 = wid::_Location {file:#C35, line:#C9, column:#C44, name:#C30, parameterLocations:#C1}
+  #C46 = 12.0
+  #C47 = 31.0
+  #C48 = "FooExtension|get#getterFoo"
+  #C49 = wid::_Location {file:#C35, line:#C46, column:#C47, name:#C48, parameterLocations:#C1}
+  #C50 = 13.0
+  #C51 = 37.0
+  #C52 = "FooExtension|set#setterFoo"
+  #C53 = wid::_Location {file:#C35, line:#C50, column:#C51, name:#C52, parameterLocations:#C1}
+  #C54 = 14.0
+  #C55 = 28.0
+  #C56 = "FooExtension|unary-"
+  #C57 = wid::_Location {file:#C35, line:#C54, column:#C55, name:#C56, parameterLocations:#C1}
+}
+
+
+Constructor coverage from constants:
+org-dartlang-test:///main.dart:
+- _Location. (from org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:7:9)
+- Object. (from org-dartlang-sdk:///lib/core/object.dart)
+
+org-dartlang-test:///foo.dart:
+- _Location. (from org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:7:9)
+- Object. (from org-dartlang-sdk:///lib/core/object.dart)
+- Foo._ (from org-dartlang-test:///foo.dart:10:9)
+- Widget. (from org-dartlang-test:///flutter/lib/src/widgets/framework.dart:7:9)
+- Bar. (from org-dartlang-test:///flutter/lib/src/widgets/framework.dart:4:9)
+
+org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:
+- _WidgetFactory. (from org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:27:9)
+- Object. (from org-dartlang-sdk:///lib/core/object.dart)
+
diff --git a/pkg/front_end/testcases/incremental/flutter_widget_factory.yaml.world.2.expect b/pkg/front_end/testcases/incremental/flutter_widget_factory.yaml.world.2.expect
new file mode 100644
index 00000000000..77e8b035636
--- /dev/null
+++ b/pkg/front_end/testcases/incremental/flutter_widget_factory.yaml.world.2.expect
@@ -0,0 +1,216 @@
+main = <No Member>;
+library from "package:flutter/src/widgets/framework.dart" as fra {
+additionalExports = (wid::widgetFactory)
+
+  export "package:flutter/src/widgets/widget_inspector.dart" show widgetFactory;
+
+  abstract class Bar extends dart.core::Object /*hasConstConstructor*/  {
+    const constructor •() → fra::Bar
+      : super dart.core::Object::•()
+      ;
+  }
+  abstract class Widget extends fra::Bar implements wid::_HasCreationLocation /*hasConstConstructor*/  {
+    final field wid::_Location? _location /*isLegacy*/;
+    const constructor •({wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → fra::Widget
+      : super fra::Bar::•(), fra::Widget::_location = $creationLocationd_0dea112b090073317d4
+      ;
+  }
+}
+library from "package:flutter/src/widgets/widget_inspector.dart" as wid {
+
+  abstract class _HasCreationLocation extends dart.core::Object {
+    synthetic constructor •() → wid::_HasCreationLocation
+      : super dart.core::Object::•()
+      ;
+    abstract get _location() → wid::_Location;
+  }
+  class _Location extends dart.core::Object /*hasConstConstructor*/  {
+    final field dart.core::String file;
+    final field dart.core::int line;
+    final field dart.core::int column;
+    final field dart.core::String name;
+    final field dart.core::List<wid::_Location> parameterLocations;
+    const constructor •({required dart.core::String file = #C1, required dart.core::int line = #C1, required dart.core::int column = #C1, required dart.core::String name = #C1, required dart.core::List<wid::_Location> parameterLocations = #C1}) → wid::_Location
+      : wid::_Location::file = file, wid::_Location::line = line, wid::_Location::column = column, wid::_Location::name = name, wid::_Location::parameterLocations = parameterLocations, super dart.core::Object::•()
+      ;
+    static method _#new#tearOff({required dart.core::String file = #C1, required dart.core::int line = #C1, required dart.core::int column = #C1, required dart.core::String name = #C1, required dart.core::List<wid::_Location> parameterLocations = #C1}) → wid::_Location
+      return new wid::_Location::•(file: file, line: line, column: column, name: name, parameterLocations: parameterLocations);
+  }
+  class _WidgetFactory extends dart.core::Object /*hasConstConstructor*/  {
+    const constructor •() → wid::_WidgetFactory
+      : super dart.core::Object::•()
+      ;
+    static method _#new#tearOff() → wid::_WidgetFactory
+      return new wid::_WidgetFactory::•();
+  }
+  static const field wid::_WidgetFactory widgetFactory = #C2;
+}
+library from "org-dartlang-test:///foo.dart" as foo {
+
+  import "package:flutter/src/widgets/framework.dart";
+
+  class Foo extends fra::Widget /*hasConstConstructor*/  {
+    const constructor _({wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+      : super fra::Widget::•($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4)
+      ;
+    static factory •({wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+      return #C8;
+    static method _#new#tearOff() → foo::Foo
+      return foo::Foo::•($creationLocationd_0dea112b090073317d4: #C10);
+    static method _#_#tearOff() → foo::Foo
+      return new foo::Foo::_($creationLocationd_0dea112b090073317d4: #C13);
+  }
+  extension FooExtension on dart.core::Object? {
+    method foo = foo::FooExtension|foo;
+    tearoff foo = foo::FooExtension|get#foo;
+    method bar = foo::FooExtension|bar;
+    tearoff bar = foo::FooExtension|get#bar;
+    method baz = foo::FooExtension|baz;
+    tearoff baz = foo::FooExtension|get#baz;
+    method boz = foo::FooExtension|boz;
+    tearoff boz = foo::FooExtension|get#boz;
+    method constFoo = foo::FooExtension|constFoo;
+    tearoff constFoo = foo::FooExtension|get#constFoo;
+    get getterFoo = foo::FooExtension|get#getterFoo;
+    operator unary- = foo::FooExtension|unary-;
+    static method staticFoo = foo::FooExtension|staticFoo;
+    set setterFoo = foo::FooExtension|set#setterFoo;
+  }
+  static const field wid::_WidgetFactory alias = #C2;
+  static const field wid::_WidgetFactory? nullableAlias = #C1;
+  static const field wid::_WidgetFactory nonNullableAlias = #C2;
+  @#C2
+  static method FooExtension|foo(lowered final dart.core::Object? #this, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#foo(lowered final dart.core::Object? #this) → () → foo::Foo
+    return () → foo::Foo => foo::FooExtension|foo(#this, $creationLocationd_0dea112b090073317d4: #C17);
+  @#C2
+  static method FooExtension|bar(lowered final dart.core::Object? #this, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#bar(lowered final dart.core::Object? #this) → () → foo::Foo
+    return () → foo::Foo => foo::FooExtension|bar(#this, $creationLocationd_0dea112b090073317d4: #C20);
+  @#C1
+  static method FooExtension|baz(lowered final dart.core::Object? #this) → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: #C23);
+  static method FooExtension|get#baz(lowered final dart.core::Object? #this) → () → foo::Foo
+    return () → foo::Foo => foo::FooExtension|baz(#this);
+  @#C2
+  static method FooExtension|boz(lowered final dart.core::Object? #this, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#boz(lowered final dart.core::Object? #this) → () → foo::Foo
+    return () → foo::Foo => foo::FooExtension|boz(#this, $creationLocationd_0dea112b090073317d4: #C26);
+  @#C2
+  static method FooExtension|constFoo(lowered final dart.core::Object? #this, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+    return #C29;
+  static method FooExtension|get#constFoo(lowered final dart.core::Object? #this) → () → foo::Foo
+    return () → foo::Foo => foo::FooExtension|constFoo(#this, $creationLocationd_0dea112b090073317d4: #C31);
+  @#C2
+  static method FooExtension|get#getterFoo(lowered final dart.core::Object? #this, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  @#C2
+  static method FooExtension|set#setterFoo(lowered final dart.core::Object? #this, dynamic _, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → void
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  @#C2
+  static method FooExtension|unary-(lowered final dart.core::Object? #this, {wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  @#C2
+  static method FooExtension|staticFoo() → foo::Foo
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: #C34);
+}
+library from "org-dartlang-test:///main.dart" as main {
+
+  import "org-dartlang-test:///foo.dart";
+
+  static field foo::Foo extensionConstFoo = foo::FooExtension|constFoo(null, $creationLocationd_0dea112b090073317d4: #C38);
+  static field foo::Foo newFoo = foo::Foo::•($creationLocationd_0dea112b090073317d4: #C40);
+  static field () → foo::Foo newFooFunction = #C41;
+  static field foo::Foo newFooFunctionCall = main::newFooFunction(){() → foo::Foo};
+  static field foo::Foo extensionFoo = foo::FooExtension|foo(null, $creationLocationd_0dea112b090073317d4: #C44);
+  static field ({$creationLocationd_0dea112b090073317d4: wid::_Location?}) → foo::Foo extensionFooFunction = foo::FooExtension|get#foo(null);
+  static field foo::Foo extensionFooFunctionCall = main::extensionFooFunction(){({$creationLocationd_0dea112b090073317d4: wid::_Location?}) → foo::Foo};
+  static field foo::Foo extensionBar = foo::FooExtension|bar(null, $creationLocationd_0dea112b090073317d4: #C45);
+  static field foo::Foo extensionBaz = foo::FooExtension|baz(null);
+  static field foo::Foo extensionBoz = foo::FooExtension|boz(null, $creationLocationd_0dea112b090073317d4: #C46);
+  static field foo::Foo extensionGetterFoo = foo::FooExtension|get#getterFoo(null, $creationLocationd_0dea112b090073317d4: #C50);
+  static field () → Null extensionSetterFoo = () → Null => let final has-declared-initializer Null #t1 = null in let final void #t2 = foo::FooExtension|set#setterFoo(null, #t1, $creationLocationd_0dea112b090073317d4: #C54) in #t1;
+  static field foo::Foo extensionOperatorFoo = foo::FooExtension|unary-(null, $creationLocationd_0dea112b090073317d4: #C58);
+  static field foo::Foo extensionStaticFoo = foo::FooExtension|staticFoo();
+}
+constants  {
+  #C1 = null
+  #C2 = wid::_WidgetFactory {}
+  #C3 = "org-dartlang-test:///foo.dart"
+  #C4 = 8.0
+  #C5 = 26.0
+  #C6 = "Foo"
+  #C7 = wid::_Location {file:#C3, line:#C4, column:#C5, name:#C6, parameterLocations:#C1}
+  #C8 = foo::Foo {_location:#C7}
+  #C9 = 11.0
+  #C10 = wid::_Location {file:#C3, line:#C4, column:#C9, name:#C6, parameterLocations:#C1}
+  #C11 = 10.0
+  #C12 = 9.0
+  #C13 = wid::_Location {file:#C3, line:#C11, column:#C12, name:#C6, parameterLocations:#C1}
+  #C14 = 15.0
+  #C15 = 7.0
+  #C16 = "FooExtension|foo"
+  #C17 = wid::_Location {file:#C3, line:#C14, column:#C15, name:#C16, parameterLocations:#C1}
+  #C18 = 18.0
+  #C19 = "FooExtension|bar"
+  #C20 = wid::_Location {file:#C3, line:#C18, column:#C15, name:#C19, parameterLocations:#C1}
+  #C21 = 21.0
+  #C22 = 20.0
+  #C23 = wid::_Location {file:#C3, line:#C21, column:#C22, name:#C6, parameterLocations:#C1}
+  #C24 = 24.0
+  #C25 = "FooExtension|boz"
+  #C26 = wid::_Location {file:#C3, line:#C24, column:#C15, name:#C25, parameterLocations:#C1}
+  #C27 = 27.0
+  #C28 = wid::_Location {file:#C3, line:#C27, column:#C27, name:#C6, parameterLocations:#C1}
+  #C29 = foo::Foo {_location:#C28}
+  #C30 = "FooExtension|constFoo"
+  #C31 = wid::_Location {file:#C3, line:#C27, column:#C15, name:#C30, parameterLocations:#C1}
+  #C32 = 39.0
+  #C33 = 33.0
+  #C34 = wid::_Location {file:#C3, line:#C32, column:#C33, name:#C6, parameterLocations:#C1}
+  #C35 = "org-dartlang-test:///main.dart"
+  #C36 = 2.0
+  #C37 = 30.0
+  #C38 = wid::_Location {file:#C35, line:#C36, column:#C37, name:#C30, parameterLocations:#C1}
+  #C39 = 3.0
+  #C40 = wid::_Location {file:#C35, line:#C39, column:#C18, name:#C6, parameterLocations:#C1}
+  #C41 = static-tearoff foo::Foo::_#new#tearOff
+  #C42 = 6.0
+  #C43 = 25.0
+  #C44 = wid::_Location {file:#C35, line:#C42, column:#C43, name:#C16, parameterLocations:#C1}
+  #C45 = wid::_Location {file:#C35, line:#C12, column:#C43, name:#C19, parameterLocations:#C1}
+  #C46 = wid::_Location {file:#C35, line:#C9, column:#C43, name:#C25, parameterLocations:#C1}
+  #C47 = 12.0
+  #C48 = 31.0
+  #C49 = "FooExtension|get#getterFoo"
+  #C50 = wid::_Location {file:#C35, line:#C47, column:#C48, name:#C49, parameterLocations:#C1}
+  #C51 = 13.0
+  #C52 = 37.0
+  #C53 = "FooExtension|set#setterFoo"
+  #C54 = wid::_Location {file:#C35, line:#C51, column:#C52, name:#C53, parameterLocations:#C1}
+  #C55 = 14.0
+  #C56 = 28.0
+  #C57 = "FooExtension|unary-"
+  #C58 = wid::_Location {file:#C35, line:#C55, column:#C56, name:#C57, parameterLocations:#C1}
+}
+
+
+Constructor coverage from constants:
+org-dartlang-test:///foo.dart:
+- _Location. (from org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:7:9)
+- Object. (from org-dartlang-sdk:///lib/core/object.dart)
+- Foo._ (from org-dartlang-test:///foo.dart:10:9)
+- Widget. (from org-dartlang-test:///flutter/lib/src/widgets/framework.dart:7:9)
+- Bar. (from org-dartlang-test:///flutter/lib/src/widgets/framework.dart:4:9)
+
+org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:
+- _WidgetFactory. (from org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:27:9)
+- Object. (from org-dartlang-sdk:///lib/core/object.dart)
+
+org-dartlang-test:///main.dart:
+- _Location. (from org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:7:9)
+- Object. (from org-dartlang-sdk:///lib/core/object.dart)
+
diff --git a/pkg/front_end/testcases/incremental/flutter_widget_factory_legacy.yaml b/pkg/front_end/testcases/incremental/flutter_widget_factory_legacy.yaml
new file mode 100644
index 00000000000..1f79d1d707c
--- /dev/null
+++ b/pkg/front_end/testcases/incremental/flutter_widget_factory_legacy.yaml
@@ -0,0 +1,125 @@
+# 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.md file.
+
+type: newworld
+target: dartdevc
+trackWidgetCreation: true
+worlds:
+  - entry: main.dart
+    sources:
+      main.dart: |
+        import 'foo.dart';
+        Foo newFoo = new Foo();
+        var newFooFunction = Foo.new;
+        var newFooFunctionCall = newFooFunction();
+        Foo extensionFoo = null.foo();
+        var extensionFooFunction = null.foo;
+        var extensionFooFunctionCall = extensionFooFunction();
+        Foo extensionBar = null.bar();
+        Foo extensionBaz = null.baz();
+        Foo extensionBoz = null.boz();
+        Foo extensionConstFoo = null.constFoo();
+      foo.dart: |
+        // @dart=2.9
+        import 'package:flutter/src/widgets/framework.dart';
+
+        const alias = widgetFactory;
+        const nullableAlias = false ? widgetFactory : null;
+        const nonNullableAlias = false ? widgetFactory : alias;
+
+        class Foo extends Widget {
+          factory Foo() => const Foo._();
+
+          const Foo._();
+        }
+
+        extension FooExtension on Object {
+          @widgetFactory
+          Foo foo() => Foo._();
+
+          @alias
+          Foo bar() => Foo._();
+
+          @nullableAlias
+          Foo baz() => Foo._();
+
+          @nonNullableAlias
+          Foo boz() => Foo._();
+
+          @widgetFactory
+          Foo constFoo() => const Foo._();
+        }
+      flutter/lib/src/widgets/framework.dart: |
+        export 'widget_inspector.dart' show widgetFactory;
+
+        abstract class Bar {
+          const Bar();
+        }
+        abstract class Widget extends Bar {
+          const Widget();
+        }
+      flutter/lib/src/widgets/widget_inspector.dart: |
+        abstract class _HasCreationLocation {
+          _Location get _location;
+        }
+        /// A tuple with file, line, and column number, for displaying human-readable
+        /// file locations.
+        class _Location {
+          const _Location({
+            required this.file,
+            required this.line,
+            required this.column,
+            required this.name,
+            required this.parameterLocations,
+          });
+          /// File path of the location.
+          final String file;
+          /// 1-based line number.
+          final int line;
+          /// 1-based column number.
+          final int column;
+          /// Optional name of the parameter or function at this location.
+          final String name;
+          /// Optional locations of the parameters of the member at this location.
+          final List<_Location> parameterLocations;
+        }
+
+        class _WidgetFactory {
+          const _WidgetFactory();
+        }
+
+        const widgetFactory = _WidgetFactory();
+      .dart_tool/package_config.json: |
+        {
+          "configVersion": 2,
+          "packages": [
+            {
+              "name": "flutter",
+              "rootUri": "../flutter",
+              "packageUri": "lib/"
+            }
+          ]
+        }
+    expectedLibraryCount: 4
+
+  - entry: main.dart
+    worldType: updated
+    invalidate:
+      - main.dart
+    expectInitializeFromDill: false
+    sources:
+      main.dart: |
+        import 'foo.dart';
+        Foo extensionConstFoo = null.constFoo();
+        Foo newFoo = new Foo();
+        var newFooFunction = Foo.new;
+        var newFooFunctionCall = newFooFunction();
+        Foo extensionFoo = null.foo();
+        var extensionFooFunction = null.foo;
+        var extensionFooFunctionCall = extensionFooFunction();
+        Foo extensionBar = null.bar();
+        Foo extensionBaz = null.baz();
+        Foo extensionBoz = null.boz();
+    expectedLibraryCount: 4
+    advancedInvalidation: bodiesOnly
diff --git a/pkg/front_end/testcases/incremental/flutter_widget_factory_legacy.yaml.world.1.expect b/pkg/front_end/testcases/incremental/flutter_widget_factory_legacy.yaml.world.1.expect
new file mode 100644
index 00000000000..b99d086bc15
--- /dev/null
+++ b/pkg/front_end/testcases/incremental/flutter_widget_factory_legacy.yaml.world.1.expect
@@ -0,0 +1,187 @@
+main = <No Member>;
+library from "package:flutter/src/widgets/framework.dart" as fra {
+additionalExports = (wid::widgetFactory)
+
+  export "package:flutter/src/widgets/widget_inspector.dart" show widgetFactory;
+
+  abstract class Bar extends dart.core::Object /*hasConstConstructor*/  {
+    const constructor •() → fra::Bar
+      : super dart.core::Object::•()
+      ;
+  }
+  abstract class Widget extends fra::Bar implements wid::_HasCreationLocation /*hasConstConstructor*/  {
+    final field wid::_Location? _location /*isLegacy*/;
+    const constructor •({wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → fra::Widget
+      : super fra::Bar::•(), fra::Widget::_location = $creationLocationd_0dea112b090073317d4
+      ;
+  }
+}
+library from "package:flutter/src/widgets/widget_inspector.dart" as wid {
+
+  abstract class _HasCreationLocation extends dart.core::Object {
+    synthetic constructor •() → wid::_HasCreationLocation
+      : super dart.core::Object::•()
+      ;
+    abstract get _location() → wid::_Location;
+  }
+  class _Location extends dart.core::Object /*hasConstConstructor*/  {
+    final field dart.core::String file;
+    final field dart.core::int line;
+    final field dart.core::int column;
+    final field dart.core::String name;
+    final field dart.core::List<wid::_Location> parameterLocations;
+    const constructor •({required dart.core::String file = #C1, required dart.core::int line = #C1, required dart.core::int column = #C1, required dart.core::String name = #C1, required dart.core::List<wid::_Location> parameterLocations = #C1}) → wid::_Location
+      : wid::_Location::file = file, wid::_Location::line = line, wid::_Location::column = column, wid::_Location::name = name, wid::_Location::parameterLocations = parameterLocations, super dart.core::Object::•()
+      ;
+    static method _#new#tearOff({required dart.core::String file = #C1, required dart.core::int line = #C1, required dart.core::int column = #C1, required dart.core::String name = #C1, required dart.core::List<wid::_Location> parameterLocations = #C1}) → wid::_Location
+      return new wid::_Location::•(file: file, line: line, column: column, name: name, parameterLocations: parameterLocations);
+  }
+  class _WidgetFactory extends dart.core::Object /*hasConstConstructor*/  {
+    const constructor •() → wid::_WidgetFactory
+      : super dart.core::Object::•()
+      ;
+    static method _#new#tearOff() → wid::_WidgetFactory
+      return new wid::_WidgetFactory::•();
+  }
+  static const field wid::_WidgetFactory widgetFactory = #C2;
+}
+library from "org-dartlang-test:///foo.dart" as foo {
+
+  import "package:flutter/src/widgets/framework.dart";
+
+  class Foo extends fra::Widget /*hasConstConstructor*/  {
+    const constructor _({wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+      : super fra::Widget::•($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4)
+      ;
+    static factory •({wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+      return #C8;
+    static method _#new#tearOff() → foo::Foo*
+      return foo::Foo::•($creationLocationd_0dea112b090073317d4: #C10);
+    static method _#_#tearOff() → foo::Foo*
+      return new foo::Foo::_($creationLocationd_0dea112b090073317d4: #C11);
+    abstract member-signature method noSuchMethod(dart.core::Invocation* invocation) → dynamic; -> dart.core::Object::noSuchMethod
+    abstract member-signature operator ==(dynamic other) → dart.core::bool*; -> dart.core::Object::==
+    abstract member-signature get hashCode() → dart.core::int*; -> dart.core::Object::hashCode
+    abstract member-signature method toString() → dart.core::String*; -> dart.core::Object::toString
+    abstract member-signature get runtimeType() → dart.core::Type*; -> dart.core::Object::runtimeType
+  }
+  extension FooExtension on dart.core::Object* {
+    method foo = foo::FooExtension|foo;
+    tearoff foo = foo::FooExtension|get#foo;
+    method bar = foo::FooExtension|bar;
+    tearoff bar = foo::FooExtension|get#bar;
+    method baz = foo::FooExtension|baz;
+    tearoff baz = foo::FooExtension|get#baz;
+    method boz = foo::FooExtension|boz;
+    tearoff boz = foo::FooExtension|get#boz;
+    method constFoo = foo::FooExtension|constFoo;
+    tearoff constFoo = foo::FooExtension|get#constFoo;
+  }
+  static const field wid::_WidgetFactory* alias = #C2;
+  static const field wid::_WidgetFactory* nullableAlias = #C1;
+  static const field wid::_WidgetFactory* nonNullableAlias = #C2;
+  @#C2
+  static method FooExtension|foo(lowered final dart.core::Object* #this, {wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#foo(lowered final dart.core::Object* #this) → () →* foo::Foo*
+    return () → foo::Foo* => foo::FooExtension|foo(#this, $creationLocationd_0dea112b090073317d4: #C15);
+  @#C2
+  static method FooExtension|bar(lowered final dart.core::Object* #this, {wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#bar(lowered final dart.core::Object* #this) → () →* foo::Foo*
+    return () → foo::Foo* => foo::FooExtension|bar(#this, $creationLocationd_0dea112b090073317d4: #C18);
+  @#C1
+  static method FooExtension|baz(lowered final dart.core::Object* #this, {wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#baz(lowered final dart.core::Object* #this) → () →* foo::Foo*
+    return () → foo::Foo* => foo::FooExtension|baz(#this, $creationLocationd_0dea112b090073317d4: #C21);
+  @#C2
+  static method FooExtension|boz(lowered final dart.core::Object* #this, {wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#boz(lowered final dart.core::Object* #this) → () →* foo::Foo*
+    return () → foo::Foo* => foo::FooExtension|boz(#this, $creationLocationd_0dea112b090073317d4: #C24);
+  @#C2
+  static method FooExtension|constFoo(lowered final dart.core::Object* #this, {wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+    return #C28;
+  static method FooExtension|get#constFoo(lowered final dart.core::Object* #this) → () →* foo::Foo*
+    return () → foo::Foo* => foo::FooExtension|constFoo(#this, $creationLocationd_0dea112b090073317d4: #C30);
+}
+library from "org-dartlang-test:///main.dart" as main {
+
+  import "org-dartlang-test:///foo.dart";
+
+  static field foo::Foo newFoo = foo::Foo::•($creationLocationd_0dea112b090073317d4: #C34);
+  static field () → foo::Foo newFooFunction = #C35;
+  static field foo::Foo newFooFunctionCall = main::newFooFunction(){() → foo::Foo};
+  static field foo::Foo extensionFoo = foo::FooExtension|foo(null, $creationLocationd_0dea112b090073317d4: #C37);
+  static field () → foo::Foo extensionFooFunction = foo::FooExtension|get#foo(null);
+  static field foo::Foo extensionFooFunctionCall = main::extensionFooFunction(){() → foo::Foo};
+  static field foo::Foo extensionBar = foo::FooExtension|bar(null, $creationLocationd_0dea112b090073317d4: #C39);
+  static field foo::Foo extensionBaz = foo::FooExtension|baz(null, $creationLocationd_0dea112b090073317d4: #C40);
+  static field foo::Foo extensionBoz = foo::FooExtension|boz(null, $creationLocationd_0dea112b090073317d4: #C42);
+  static field foo::Foo extensionConstFoo = foo::FooExtension|constFoo(null, $creationLocationd_0dea112b090073317d4: #C44);
+}
+constants  {
+  #C1 = null
+  #C2 = wid::_WidgetFactory {}
+  #C3 = "org-dartlang-test:///foo.dart"
+  #C4 = 9.0
+  #C5 = 26.0
+  #C6 = "Foo"
+  #C7 = wid::_Location {file:#C3, line:#C4, column:#C5, name:#C6, parameterLocations:#C1}
+  #C8 = foo::Foo {_location:#C7}
+  #C9 = 11.0
+  #C10 = wid::_Location {file:#C3, line:#C4, column:#C9, name:#C6, parameterLocations:#C1}
+  #C11 = wid::_Location {file:#C3, line:#C9, column:#C4, name:#C6, parameterLocations:#C1}
+  #C12 = 16.0
+  #C13 = 7.0
+  #C14 = "FooExtension|foo"
+  #C15 = wid::_Location {file:#C3, line:#C12, column:#C13, name:#C14, parameterLocations:#C1}
+  #C16 = 19.0
+  #C17 = "FooExtension|bar"
+  #C18 = wid::_Location {file:#C3, line:#C16, column:#C13, name:#C17, parameterLocations:#C1}
+  #C19 = 22.0
+  #C20 = "FooExtension|baz"
+  #C21 = wid::_Location {file:#C3, line:#C19, column:#C13, name:#C20, parameterLocations:#C1}
+  #C22 = 25.0
+  #C23 = "FooExtension|boz"
+  #C24 = wid::_Location {file:#C3, line:#C22, column:#C13, name:#C23, parameterLocations:#C1}
+  #C25 = 28.0
+  #C26 = 27.0
+  #C27 = wid::_Location {file:#C3, line:#C25, column:#C26, name:#C6, parameterLocations:#C1}
+  #C28 = foo::Foo {_location:#C27}
+  #C29 = "FooExtension|constFoo"
+  #C30 = wid::_Location {file:#C3, line:#C25, column:#C13, name:#C29, parameterLocations:#C1}
+  #C31 = "org-dartlang-test:///main.dart"
+  #C32 = 2.0
+  #C33 = 18.0
+  #C34 = wid::_Location {file:#C31, line:#C32, column:#C33, name:#C6, parameterLocations:#C1}
+  #C35 = static-tearoff foo::Foo::_#new#tearOff
+  #C36 = 5.0
+  #C37 = wid::_Location {file:#C31, line:#C36, column:#C22, name:#C14, parameterLocations:#C1}
+  #C38 = 8.0
+  #C39 = wid::_Location {file:#C31, line:#C38, column:#C22, name:#C17, parameterLocations:#C1}
+  #C40 = wid::_Location {file:#C31, line:#C4, column:#C22, name:#C20, parameterLocations:#C1}
+  #C41 = 10.0
+  #C42 = wid::_Location {file:#C31, line:#C41, column:#C22, name:#C23, parameterLocations:#C1}
+  #C43 = 30.0
+  #C44 = wid::_Location {file:#C31, line:#C9, column:#C43, name:#C29, parameterLocations:#C1}
+}
+
+
+Constructor coverage from constants:
+org-dartlang-test:///main.dart:
+- _Location. (from org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:7:9)
+- Object. (from org-dartlang-sdk:///lib/core/object.dart)
+
+org-dartlang-test:///foo.dart:
+- _Location. (from org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:7:9)
+- Object. (from org-dartlang-sdk:///lib/core/object.dart)
+- Foo._ (from org-dartlang-test:///foo.dart:11:9)
+- Widget. (from org-dartlang-test:///flutter/lib/src/widgets/framework.dart:7:9)
+- Bar. (from org-dartlang-test:///flutter/lib/src/widgets/framework.dart:4:9)
+
+org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:
+- _WidgetFactory. (from org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:27:9)
+- Object. (from org-dartlang-sdk:///lib/core/object.dart)
+
diff --git a/pkg/front_end/testcases/incremental/flutter_widget_factory_legacy.yaml.world.2.expect b/pkg/front_end/testcases/incremental/flutter_widget_factory_legacy.yaml.world.2.expect
new file mode 100644
index 00000000000..b722a36a32b
--- /dev/null
+++ b/pkg/front_end/testcases/incremental/flutter_widget_factory_legacy.yaml.world.2.expect
@@ -0,0 +1,187 @@
+main = <No Member>;
+library from "package:flutter/src/widgets/framework.dart" as fra {
+additionalExports = (wid::widgetFactory)
+
+  export "package:flutter/src/widgets/widget_inspector.dart" show widgetFactory;
+
+  abstract class Bar extends dart.core::Object /*hasConstConstructor*/  {
+    const constructor •() → fra::Bar
+      : super dart.core::Object::•()
+      ;
+  }
+  abstract class Widget extends fra::Bar implements wid::_HasCreationLocation /*hasConstConstructor*/  {
+    final field wid::_Location? _location /*isLegacy*/;
+    const constructor •({wid::_Location? $creationLocationd_0dea112b090073317d4 = #C1}) → fra::Widget
+      : super fra::Bar::•(), fra::Widget::_location = $creationLocationd_0dea112b090073317d4
+      ;
+  }
+}
+library from "package:flutter/src/widgets/widget_inspector.dart" as wid {
+
+  abstract class _HasCreationLocation extends dart.core::Object {
+    synthetic constructor •() → wid::_HasCreationLocation
+      : super dart.core::Object::•()
+      ;
+    abstract get _location() → wid::_Location;
+  }
+  class _Location extends dart.core::Object /*hasConstConstructor*/  {
+    final field dart.core::String file;
+    final field dart.core::int line;
+    final field dart.core::int column;
+    final field dart.core::String name;
+    final field dart.core::List<wid::_Location> parameterLocations;
+    const constructor •({required dart.core::String file = #C1, required dart.core::int line = #C1, required dart.core::int column = #C1, required dart.core::String name = #C1, required dart.core::List<wid::_Location> parameterLocations = #C1}) → wid::_Location
+      : wid::_Location::file = file, wid::_Location::line = line, wid::_Location::column = column, wid::_Location::name = name, wid::_Location::parameterLocations = parameterLocations, super dart.core::Object::•()
+      ;
+    static method _#new#tearOff({required dart.core::String file = #C1, required dart.core::int line = #C1, required dart.core::int column = #C1, required dart.core::String name = #C1, required dart.core::List<wid::_Location> parameterLocations = #C1}) → wid::_Location
+      return new wid::_Location::•(file: file, line: line, column: column, name: name, parameterLocations: parameterLocations);
+  }
+  class _WidgetFactory extends dart.core::Object /*hasConstConstructor*/  {
+    const constructor •() → wid::_WidgetFactory
+      : super dart.core::Object::•()
+      ;
+    static method _#new#tearOff() → wid::_WidgetFactory
+      return new wid::_WidgetFactory::•();
+  }
+  static const field wid::_WidgetFactory widgetFactory = #C2;
+}
+library from "org-dartlang-test:///foo.dart" as foo {
+
+  import "package:flutter/src/widgets/framework.dart";
+
+  class Foo extends fra::Widget /*hasConstConstructor*/  {
+    const constructor _({wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+      : super fra::Widget::•($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4)
+      ;
+    static factory •({wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+      return #C8;
+    static method _#new#tearOff() → foo::Foo*
+      return foo::Foo::•($creationLocationd_0dea112b090073317d4: #C10);
+    static method _#_#tearOff() → foo::Foo*
+      return new foo::Foo::_($creationLocationd_0dea112b090073317d4: #C11);
+    abstract member-signature method noSuchMethod(dart.core::Invocation* invocation) → dynamic; -> dart.core::Object::noSuchMethod
+    abstract member-signature operator ==(dynamic other) → dart.core::bool*; -> dart.core::Object::==
+    abstract member-signature get hashCode() → dart.core::int*; -> dart.core::Object::hashCode
+    abstract member-signature method toString() → dart.core::String*; -> dart.core::Object::toString
+    abstract member-signature get runtimeType() → dart.core::Type*; -> dart.core::Object::runtimeType
+  }
+  extension FooExtension on dart.core::Object* {
+    method foo = foo::FooExtension|foo;
+    tearoff foo = foo::FooExtension|get#foo;
+    method bar = foo::FooExtension|bar;
+    tearoff bar = foo::FooExtension|get#bar;
+    method baz = foo::FooExtension|baz;
+    tearoff baz = foo::FooExtension|get#baz;
+    method boz = foo::FooExtension|boz;
+    tearoff boz = foo::FooExtension|get#boz;
+    method constFoo = foo::FooExtension|constFoo;
+    tearoff constFoo = foo::FooExtension|get#constFoo;
+  }
+  static const field wid::_WidgetFactory* alias = #C2;
+  static const field wid::_WidgetFactory* nullableAlias = #C1;
+  static const field wid::_WidgetFactory* nonNullableAlias = #C2;
+  @#C2
+  static method FooExtension|foo(lowered final dart.core::Object* #this, {wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#foo(lowered final dart.core::Object* #this) → () →* foo::Foo*
+    return () → foo::Foo* => foo::FooExtension|foo(#this, $creationLocationd_0dea112b090073317d4: #C15);
+  @#C2
+  static method FooExtension|bar(lowered final dart.core::Object* #this, {wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#bar(lowered final dart.core::Object* #this) → () →* foo::Foo*
+    return () → foo::Foo* => foo::FooExtension|bar(#this, $creationLocationd_0dea112b090073317d4: #C18);
+  @#C1
+  static method FooExtension|baz(lowered final dart.core::Object* #this, {wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#baz(lowered final dart.core::Object* #this) → () →* foo::Foo*
+    return () → foo::Foo* => foo::FooExtension|baz(#this, $creationLocationd_0dea112b090073317d4: #C21);
+  @#C2
+  static method FooExtension|boz(lowered final dart.core::Object* #this, {wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+    return new foo::Foo::_($creationLocationd_0dea112b090073317d4: $creationLocationd_0dea112b090073317d4);
+  static method FooExtension|get#boz(lowered final dart.core::Object* #this) → () →* foo::Foo*
+    return () → foo::Foo* => foo::FooExtension|boz(#this, $creationLocationd_0dea112b090073317d4: #C24);
+  @#C2
+  static method FooExtension|constFoo(lowered final dart.core::Object* #this, {wid::_Location* $creationLocationd_0dea112b090073317d4 = #C1}) → foo::Foo*
+    return #C28;
+  static method FooExtension|get#constFoo(lowered final dart.core::Object* #this) → () →* foo::Foo*
+    return () → foo::Foo* => foo::FooExtension|constFoo(#this, $creationLocationd_0dea112b090073317d4: #C30);
+}
+library from "org-dartlang-test:///main.dart" as main {
+
+  import "org-dartlang-test:///foo.dart";
+
+  static field foo::Foo extensionConstFoo = foo::FooExtension|constFoo(null, $creationLocationd_0dea112b090073317d4: #C34);
+  static field foo::Foo newFoo = foo::Foo::•($creationLocationd_0dea112b090073317d4: #C37);
+  static field () → foo::Foo newFooFunction = #C38;
+  static field foo::Foo newFooFunctionCall = main::newFooFunction(){() → foo::Foo};
+  static field foo::Foo extensionFoo = foo::FooExtension|foo(null, $creationLocationd_0dea112b090073317d4: #C40);
+  static field ({$creationLocationd_0dea112b090073317d4: wid::_Location}) → foo::Foo extensionFooFunction = foo::FooExtension|get#foo(null);
+  static field foo::Foo extensionFooFunctionCall = main::extensionFooFunction(){({$creationLocationd_0dea112b090073317d4: wid::_Location}) → foo::Foo};
+  static field foo::Foo extensionBar = foo::FooExtension|bar(null, $creationLocationd_0dea112b090073317d4: #C41);
+  static field foo::Foo extensionBaz = foo::FooExtension|baz(null, $creationLocationd_0dea112b090073317d4: #C43);
+  static field foo::Foo extensionBoz = foo::FooExtension|boz(null, $creationLocationd_0dea112b090073317d4: #C44);
+}
+constants  {
+  #C1 = null
+  #C2 = wid::_WidgetFactory {}
+  #C3 = "org-dartlang-test:///foo.dart"
+  #C4 = 9.0
+  #C5 = 26.0
+  #C6 = "Foo"
+  #C7 = wid::_Location {file:#C3, line:#C4, column:#C5, name:#C6, parameterLocations:#C1}
+  #C8 = foo::Foo {_location:#C7}
+  #C9 = 11.0
+  #C10 = wid::_Location {file:#C3, line:#C4, column:#C9, name:#C6, parameterLocations:#C1}
+  #C11 = wid::_Location {file:#C3, line:#C9, column:#C4, name:#C6, parameterLocations:#C1}
+  #C12 = 16.0
+  #C13 = 7.0
+  #C14 = "FooExtension|foo"
+  #C15 = wid::_Location {file:#C3, line:#C12, column:#C13, name:#C14, parameterLocations:#C1}
+  #C16 = 19.0
+  #C17 = "FooExtension|bar"
+  #C18 = wid::_Location {file:#C3, line:#C16, column:#C13, name:#C17, parameterLocations:#C1}
+  #C19 = 22.0
+  #C20 = "FooExtension|baz"
+  #C21 = wid::_Location {file:#C3, line:#C19, column:#C13, name:#C20, parameterLocations:#C1}
+  #C22 = 25.0
+  #C23 = "FooExtension|boz"
+  #C24 = wid::_Location {file:#C3, line:#C22, column:#C13, name:#C23, parameterLocations:#C1}
+  #C25 = 28.0
+  #C26 = 27.0
+  #C27 = wid::_Location {file:#C3, line:#C25, column:#C26, name:#C6, parameterLocations:#C1}
+  #C28 = foo::Foo {_location:#C27}
+  #C29 = "FooExtension|constFoo"
+  #C30 = wid::_Location {file:#C3, line:#C25, column:#C13, name:#C29, parameterLocations:#C1}
+  #C31 = "org-dartlang-test:///main.dart"
+  #C32 = 2.0
+  #C33 = 30.0
+  #C34 = wid::_Location {file:#C31, line:#C32, column:#C33, name:#C29, parameterLocations:#C1}
+  #C35 = 3.0
+  #C36 = 18.0
+  #C37 = wid::_Location {file:#C31, line:#C35, column:#C36, name:#C6, parameterLocations:#C1}
+  #C38 = static-tearoff foo::Foo::_#new#tearOff
+  #C39 = 6.0
+  #C40 = wid::_Location {file:#C31, line:#C39, column:#C22, name:#C14, parameterLocations:#C1}
+  #C41 = wid::_Location {file:#C31, line:#C4, column:#C22, name:#C17, parameterLocations:#C1}
+  #C42 = 10.0
+  #C43 = wid::_Location {file:#C31, line:#C42, column:#C22, name:#C20, parameterLocations:#C1}
+  #C44 = wid::_Location {file:#C31, line:#C9, column:#C22, name:#C23, parameterLocations:#C1}
+}
+
+
+Constructor coverage from constants:
+org-dartlang-test:///foo.dart:
+- _Location. (from org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:7:9)
+- Object. (from org-dartlang-sdk:///lib/core/object.dart)
+- Foo._ (from org-dartlang-test:///foo.dart:11:9)
+- Widget. (from org-dartlang-test:///flutter/lib/src/widgets/framework.dart:7:9)
+- Bar. (from org-dartlang-test:///flutter/lib/src/widgets/framework.dart:4:9)
+
+org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:
+- _WidgetFactory. (from org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:27:9)
+- Object. (from org-dartlang-sdk:///lib/core/object.dart)
+
+org-dartlang-test:///main.dart:
+- _Location. (from org-dartlang-test:///flutter/lib/src/widgets/widget_inspector.dart:7:9)
+- Object. (from org-dartlang-sdk:///lib/core/object.dart)
+
diff --git a/pkg/kernel/lib/transformations/track_widget_constructor_locations.dart b/pkg/kernel/lib/transformations/track_widget_constructor_locations.dart
index 736060b81f6..ab65caf3538 100644
--- a/pkg/kernel/lib/transformations/track_widget_constructor_locations.dart
+++ b/pkg/kernel/lib/transformations/track_widget_constructor_locations.dart
@@ -103,22 +103,37 @@ bool _maybeAddNamedParameter(
   return true;
 }
 
-/// Transformer that modifies all calls to Widget constructors to include
-/// a [DebugLocation] parameter specifying the location where the constructor
-/// call was made.
+/// Transformer that modifies all calls to Widget constructors and "Widget
+/// factories" to include a _Location parameter specifying the location where
+/// the constructor or widget factory call was made.
 ///
-/// This transformer requires that all Widget constructors have already been
-/// transformed to have a named parameter with the name specified by
-/// `_locationParameterName`.
+/// This transformer requires that all Widget constructors and Widget factories
+/// have already been transformed to have a named parameter with the name
+/// specified by `_locationParameterName`.
+///
+/// A "Widget factory" is an extension instance method annotated with the
+/// `@widgetFactory` annotations. A _Location parameter is added to such methods
+/// and this is used as the location value for all Widget constructor
+/// invocations within the method.
 class _WidgetCallSiteTransformer extends Transformer {
   /// The [Widget] class defined in the `package:flutter` library.
   ///
-  /// Used to perform instanceof checks to determine whether Dart constructor
-  /// calls are creating [Widget] objects.
-  Class _widgetClass;
+  /// Used to perform is-tests to determine whether Dart constructor calls are
+  /// creating [Widget] objects.
+  final Class _widgetClass;
 
-  /// The [DebugLocation] class defined in the `package:flutter` library.
-  Class _locationClass;
+  /// The _Location class defined in the `package:flutter` library.
+  final Class _locationClass;
+
+  final WidgetCreatorTracker _tracker;
+
+  /// The creation location parameter of the extension factory method enclosing
+  /// the node that is currently being transformed.
+  ///
+  /// Used to flow the creation location parameter to the call sites of widget
+  /// constructors and extension factory methods within an enclosing extension
+  /// factory method.
+  Expression? _currentExtensionFactoryLocationParameter;
 
   /// Current factory constructor that node being transformed is inside.
   ///
@@ -126,23 +141,21 @@ class _WidgetCallSiteTransformer extends Transformer {
   /// actual constructor call within the factory.
   Procedure? _currentFactory;
 
-  WidgetCreatorTracker _tracker;
-
   /// Library that contains the transformed call sites.
   ///
   /// The transformation of the call sites is affected by the NNBD opt-in status
   /// of the library.
   Library? _currentLibrary;
 
-  _WidgetCallSiteTransformer(
-      {required Class widgetClass,
-      required Class locationClass,
-      required WidgetCreatorTracker tracker})
-      : _widgetClass = widgetClass,
+  _WidgetCallSiteTransformer({
+    required Class widgetClass,
+    required Class locationClass,
+    required WidgetCreatorTracker tracker,
+  })  : _widgetClass = widgetClass,
         _locationClass = locationClass,
         _tracker = tracker;
 
-  /// Builds a call to the const constructor of the [DebugLocation]
+  /// Builds a call to the const constructor of the _Location
   /// object specifying the location where a constructor call was made and
   /// optionally the locations for all parameters passed in.
   ///
@@ -172,6 +185,17 @@ class _WidgetCallSiteTransformer extends Transformer {
 
   @override
   Procedure visitProcedure(Procedure node) {
+    if (_isWidgetFactory(node)) {
+      final VariableDeclaration locationParameter =
+          node.function.namedParameters.firstWhere(
+        (parameter) => parameter.name == _creationLocationParameterName,
+      );
+      _currentExtensionFactoryLocationParameter =
+          VariableGet(locationParameter);
+      node.transformChildren(this);
+      _currentExtensionFactoryLocationParameter = null;
+      return node;
+    }
     if (node.isFactory) {
       _currentFactory = node;
       node.transformChildren(this);
@@ -186,30 +210,55 @@ class _WidgetCallSiteTransformer extends Transformer {
     return _tracker._isSubclassOf(clazz, _widgetClass);
   }
 
+  bool _isWidgetFactory(Procedure node) {
+    return node.isExtensionMember &&
+        _hasNamedParameter(node.function, _creationLocationParameterName);
+  }
+
   @override
   StaticInvocation visitStaticInvocation(StaticInvocation node) {
     node.transformChildren(this);
     final Procedure target = node.target;
-    if (!target.isFactory) {
-      return node;
-    }
-    final Class constructedClass = target.enclosingClass!;
-    if (!_isSubclassOfWidget(constructedClass)) {
-      return node;
-    }
+    if (target.isFactory) {
+      final Class constructedClass = target.enclosingClass!;
+      if (!_isSubclassOfWidget(constructedClass)) {
+        return node;
+      }
 
-    _addLocationArgument(node, target.function, constructedClass,
-        isConst: node.isConst);
+      _addLocationArgument(
+        node,
+        target.function,
+        constructedClass: constructedClass,
+        isConst: node.isConst,
+      );
+      return node;
+    }
+    if (_isWidgetFactory(target)) {
+      _addLocationArgument(node, target.function);
+      return node;
+    }
     return node;
   }
 
   void _addLocationArgument(
-      InvocationExpression node, FunctionNode function, Class constructedClass,
-      {bool isConst = false}) {
+    InvocationExpression node,
+    FunctionNode function, {
+    Class? constructedClass,
+    bool isConst = false,
+  }) {
+    Expression? location = _currentExtensionFactoryLocationParameter;
+    if (location == null ||
+        // We cannot pass the location parameter of the enclosing extension
+        // factory method to a const constructor call, so we fallback to
+        // passing the location of the constructor call.
+        isConst) {
+      location =
+          _computeLocation(node, function, constructedClass, isConst: isConst);
+    }
     _maybeAddCreationLocationArgument(
       node.arguments,
       function,
-      _computeLocation(node, function, constructedClass, isConst: isConst),
+      location,
       _locationClass,
     );
   }
@@ -224,20 +273,27 @@ class _WidgetCallSiteTransformer extends Transformer {
       return node;
     }
 
-    _addLocationArgument(node, constructor.function, constructedClass,
-        isConst: node.isConst);
+    _addLocationArgument(
+      node,
+      constructor.function,
+      constructedClass: constructedClass,
+      isConst: node.isConst,
+    );
     return node;
   }
 
   Expression _computeLocation(
     InvocationExpression node,
     FunctionNode function,
-    Class constructedClass, {
+    Class? constructedClass, {
     bool isConst = false,
   }) {
+    assert(constructedClass != null || !isConst);
+
     // For factory constructors we need to use the location specified as an
     // argument to the factory constructor rather than the location
-    if (_currentFactory != null &&
+    if (constructedClass != null &&
+        _currentFactory != null &&
         _tracker._isSubclassOf(
             constructedClass, _currentFactory!.enclosingClass!) &&
         // If the constructor invocation is constant we cannot refer to the
@@ -255,7 +311,9 @@ class _WidgetCallSiteTransformer extends Transformer {
 
     return _constructLocation(
       node.location!,
-      name: constructedClass.name,
+      name: constructedClass?.name ??
+          // For extension factory methods we use the name of the method.
+          (function.parent! as Procedure).name.text,
     );
   }
 
@@ -274,12 +332,18 @@ class _WidgetCallSiteTransformer extends Transformer {
   }
 }
 
-/// Rewrites all widget constructors and constructor invocations to add a
-/// parameter specifying the location the constructor was called from.
+/// Rewrites all Widget constructors, constructor invocations,
+/// "Widget factories", and Widget factory invocations to add a
+/// parameter specifying the location the constructor/factory was called from.
 ///
 /// The creation location is stored as a private field named `_location`
-/// on the base widget class and flowed through the constructors using a named
+/// on the base Widget class and flowed through the constructors using a named
 /// parameter.
+///
+/// A "Widget factory" is an extension instance method annotated with the
+/// `@widgetFactory` annotations. A _Location parameter is added to such methods
+/// and this is used as the location value for all Widget constructor
+/// invocations within the method.
 class WidgetCreatorTracker {
   bool _foundClasses = false;
   late Class _widgetClass;
@@ -289,6 +353,13 @@ class WidgetCreatorTracker {
   /// available.
   late Class _hasCreationLocationClass;
 
+  /// Annotation class used to mark an extension method as a "Widget factory".
+  ///
+  /// Widgets created within the body of an extension factory method will have
+  /// their creation location set to the call site of the extension factory
+  /// method.
+  Class? _widgetFactoryClass;
+
   void _resolveFlutterClasses(Iterable<Library> libraries) {
     // If the Widget or Debug location classes have been updated we need to get
     // the latest version
@@ -315,12 +386,16 @@ class WidgetCreatorTracker {
               } else if (class_.name == '_Location') {
                 _locationClass = class_;
                 foundLocationClass = true;
+              } else if (class_.name == '_WidgetFactory') {
+                _widgetFactoryClass = class_;
               }
             }
           }
         }
       }
     }
+    // TODO(johnniwinther): Require the [_widgetFactoryClass] once the
+    //  `widgetFactory` is stably in flutter.
     _foundClasses =
         foundWidgetClass && foundHasCreationLocationClass && foundLocationClass;
   }
@@ -427,7 +502,8 @@ class WidgetCreatorTracker {
   /// Transform the given [libraries].
   ///
   /// The libraries from [module] is searched for the Widget class,
-  /// the _Location class and the _HasCreationLocation class.
+  /// the _Location class, the _HasCreationLocation class and the
+  /// _WidgetFactory class.
   /// If the component does not contain them, the ones from a previous run is
   /// used (if any), otherwise no transformation is performed.
   ///
@@ -450,6 +526,7 @@ class WidgetCreatorTracker {
     }
 
     final Set<Class> transformedClasses = new Set<Class>.identity();
+    final Set<Extension> transformedExtensions = new Set<Extension>.identity();
     final Set<Library> librariesToTransform = new Set<Library>.identity()
       ..addAll(libraries);
 
@@ -462,14 +539,24 @@ class WidgetCreatorTracker {
           changedStructureNotifier,
         );
       }
+      if (_widgetFactoryClass != null) {
+        for (Extension extension in library.extensions) {
+          _transformWidgetFactories(
+            librariesToTransform,
+            transformedExtensions,
+            extension,
+          );
+        }
+      }
     }
 
     // Transform call sites to pass the location parameter.
     final _WidgetCallSiteTransformer callsiteTransformer =
         new _WidgetCallSiteTransformer(
-            widgetClass: _widgetClass,
-            locationClass: _locationClass,
-            tracker: this);
+      widgetClass: _widgetClass,
+      locationClass: _locationClass,
+      tracker: this,
+    );
 
     for (Library library in libraries) {
       callsiteTransformer.enterLibrary(library);
@@ -491,6 +578,32 @@ class WidgetCreatorTracker {
     return false;
   }
 
+  bool _hasWidgetFactoryAnnotation(Procedure node) =>
+      _isAnnotatedWithNamedValueOfType(node, _widgetFactoryClass!);
+
+  bool _isAnnotatedWithNamedValueOfType(
+    Annotatable node,
+    Class annotationClass,
+  ) {
+    return node.annotations.any((annotation) {
+      if (annotation is! StaticGet) {
+        return false;
+      }
+      final Member target = annotation.target;
+      if (target is! Field) {
+        return false;
+      }
+      final DartType type = target.type;
+      if (type is! InterfaceType) {
+        return false;
+      }
+      if (type.nullability == Nullability.nullable) {
+        return false;
+      }
+      return type.classNode == _widgetFactoryClass;
+    });
+  }
+
   void _transformWidgetConstructors(
       Set<Library> librariesToBeTransformed,
       Set<Class> transformedClasses,
@@ -583,4 +696,41 @@ class WidgetCreatorTracker {
 
     clazz.constructors.forEach(handleConstructor);
   }
+
+  void _transformWidgetFactories(
+    Set<Library> librariesToBeTransformed,
+    Set<Extension> transformedExtensions,
+    Extension extension,
+  ) {
+    // TODO(johnniwinther): We should have a lint for unsupported use of
+    // `@widgetFactory`.
+    assert(_widgetFactoryClass != null);
+
+    if (!librariesToBeTransformed.contains(extension.enclosingLibrary) ||
+        !transformedExtensions.add(extension)) {
+      return;
+    }
+
+    for (ExtensionMemberDescriptor member in extension.members) {
+      if (member.isStatic) {
+        // We could support static extension methods but it is not clear that
+        // there is a use case for this.
+        continue;
+      }
+      final Procedure method = member.member.asProcedure;
+      if (_hasWidgetFactoryAnnotation(method)) {
+        _maybeAddNamedParameter(
+          method.function,
+          new VariableDeclaration(
+            _creationLocationParameterName,
+            type: new InterfaceType(
+              _locationClass,
+              extension.enclosingLibrary.nullable,
+            ),
+            initializer: new NullLiteral(),
+          ),
+        );
+      }
+    }
+  }
 }