Workiva · btr-rmconsole-1 · Sep 21, 2026 · Aug 6, 2026 · Aug 6, 2026 · Aug 6, 2026
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -20,11 +20,16 @@ jobs:
   # Run as a separate job outside the Dart SDK matrix below,
   # since we can only emit a single SBOM.
   build:
-    uses: Workiva/gha-dart-oss/.github/workflows/build.yaml@v0.1.11
+    uses: Workiva/gha-dart-oss/.github/workflows/build.yaml@v0.1.15
+    with:
+      sdk: stable
 
   checks:
-    uses: Workiva/gha-dart-oss/.github/workflows/checks.yaml@v0.1.11
+    uses: Workiva/gha-dart-oss/.github/workflows/checks.yaml@v0.1.15
     with:
+      sdk: stable
+      # TODO re-enable this with updated formatting after this PR merges
+      format-check: false
       additional-checks: |
         no_entrypoint_imports
 
@@ -33,7 +38,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        sdk: [ 2.19.6, stable ]
+        sdk: [ 3.9.0, stable ]
     steps:
       - uses: actions/checkout@v4
       - id: setup-dart
@@ -48,15 +53,6 @@ jobs:
         name: Install dependencies
         run: dart pub get
 
-      - name: Delete Dart-2-only files and update tests when running on Dart 3
-        run: |
-          DART_VERSION="${{ steps.setup-dart.outputs.dart-version }}"
-          if [[ "$DART_VERSION" =~ ^3 ]]; then
-            ./tool/delete_dart_2_only_files.sh
-            # Stage these changes so they don't show up in the generated file `git diff` check below
-            git add .
-          fi
-
       # Analyze before generated files are created to verify that component boilerplate analysis is "clean" without the need for building
       - name: Analyze example source (pre-build)
         run: |
@@ -86,13 +82,7 @@ jobs:
       - name: Run tests (VM)
         # Can't use build_runner (which dart_dev uses if you depend on it) to run VM tests, since we get the error:
         #    Unable to spawn isolate: /…/build_runner_testRU6M77/.packages: Error: Problem in packages configuration file: Unexpected character
-        run: |
-          DART_VERSION="${{ steps.setup-dart.outputs.dart-version }}"
-          TEST_ARGS=""
-          if [[ "$DART_VERSION" =~ ^3 ]]; then
-            TEST_ARGS="--preset=no-dart-2"
-          fi
-          dart test --preset vm $TEST_ARGS
+        run: dart test --preset vm
         if: always() && steps.install.outcome == 'success' && steps.build.outcome == 'success'
 
       - name: Run tests (DDC)
@@ -112,15 +102,12 @@ jobs:
       matrix:
         sdk: [ stable ]
         analyzer:
+          - ^5.13.0 # This should match the lower bound
           - ^6.0.0
           - ^7.0.0
           - ^8.0.0
           - ^9.0.0
           - ^10.0.0
-        # Analyzer 6+ does not resolve in Dart 2.
-        include:
-          - sdk: 2.19.6
-            analyzer: ^5.13.0 # This should match the lower bound
 
     steps:
       - uses: actions/checkout@v4
@@ -140,27 +127,14 @@ jobs:
           git diff pubspec.yaml
           dart pub get
 
-      - name: Delete Dart-2-only files and update tests when running on Dart 3
-        run: |
-          DART_VERSION="${{ steps.setup-dart.outputs.dart-version }}"
-          if [[ "$DART_VERSION" =~ ^3 ]]; then
-            ./tool/delete_dart_2_only_files.sh
-          fi
-
       - name: Analyze package source
         run: dart analyze .
 
       - name: Verify builder runs without errors
         run: dart run build_runner build --build-filter='**.dart' --delete-conflicting-outputs
 
       - name: Run builder tests
-        run: |
-          DART_VERSION="${{ steps.setup-dart.outputs.dart-version }}"
-          TEST_ARGS=""
-          if [[ "$DART_VERSION" =~ ^3 ]]; then
-            TEST_ARGS="--preset=no-dart-2"
-          fi
-          dart test --preset vm $TEST_ARGS -- test/vm_tests/builder
+        run: dart test --preset vm -- test/vm_tests/builder
 
   analyzer_plugin:
     runs-on: ubuntu-latest
@@ -170,7 +144,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        sdk: [ 2.19.6, stable ]
+        sdk: [ stable ]
     steps:
       - uses: actions/checkout@v4
       - id: setup-dart
@@ -188,14 +162,6 @@ jobs:
       - id: install
         name: Install dependencies
         run: dart pub get
-        if: always() && steps.link.outcome == 'success'
-
-      - name: Delete Dart-2-only files and update tests when running on Dart 3
-        run: |
-          DART_VERSION="${{ steps.setup-dart.outputs.dart-version }}"
-          if [[ "$DART_VERSION" =~ ^3 ]]; then
-            (cd ../.. && ./tool/delete_dart_2_only_files.sh)
-          fi
 
       - name: Validate dependencies
         run: dart run dependency_validator

diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
@@ -12,4 +12,6 @@ permissions:
 
 jobs:
   publish:
-    uses: Workiva/gha-dart-oss/.github/workflows/publish.yaml@v0.1.11
+    uses: Workiva/gha-dart-oss/.github/workflows/publish.yaml@v0.1.14
+    with:
+      sdk: stable
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,19 @@
 # OverReact Changelog
 
+## Unreleased
+- Drop Dart 2 support; minimum SDK is now 3.0.0
+- Fix Dart language level 3.0 errors and downstream compile errors by switching internal classes to `mixin` declarations
+  - `GeneratedClass` - switched to `mixin`
+  - `PropsMapViewMixin`, `StateMapViewMixin`, `MapViewMixin` - switched to `mixin`, also moved `implements` to `on`
+  - Hand-authored mixin "generated" classes: 
+    - Core: `$AriaPropsMixin`, `$ConnectFluxPropsMixin`, `$CssClassPropsMixin`, `$DomPropsMixin`, `$ReactPropsMixin`, `$SvgPropsMixin`, `$UbiquitousDomPropsMixin`
+    - Components: `$ErrorBoundaryPropsMixin`, `$ErrorBoundaryStateMixin`, `$ResizeSensorPropsMixin`, `$TransitionPropsMixin`
+  - While some of these are technically a breaking changes, there's very little chance of them impacting consumers, so we're releasing it as a minor.
+
+    These classes have no known usages outside of over_react or its generated code, and are for internal use only. 
+
+    Additionally, the `*MapViewMixin` ones never should have been exported in the first place, and have been deprecated accordingly.
+
 ## 5.7.0
 - Remove `dart:mirrors` usage in builder to fix AOT compilation used in newer build_runner versions
 - Remove `dart_style` and `pub_semver` dependencies, remove generated code formatter step

diff --git a/analysis_options.yaml b/analysis_options.yaml
@@ -1,8 +1,8 @@
 include: package:workiva_analysis_options/v2.recommended.yaml
 
 analyzer:
-  strong-mode:
-    implicit-casts: false
+  language:
+    strict-casts: true
   exclude:
     - _site/**
     - test_fixtures/**

diff --git a/dart_test.yaml b/dart_test.yaml
@@ -13,14 +13,10 @@ presets:
     paths:
       - test/vm_tests/
 
-  no-dart-2:
-    exclude_tags: dart-2-only
-
   dartdevc:
     exclude_tags: no-ddc
     paths:
       - test/over_react_component_declaration_test.dart
-      - test/over_react_component_declaration_non_null_safe_test.dart
       - test/over_react_component_test.dart
       - test/over_react_dom_test.dart
       - test/over_react_prod_test.dart
@@ -31,7 +27,6 @@ presets:
     exclude_tags: ddc
     paths:
       - test/over_react_component_declaration_test.dart
-      - test/over_react_component_declaration_non_null_safe_test.dart
       - test/over_react_component_test.dart
       - test/over_react_dom_test.dart
       - test/over_react_prod_test.dart
@@ -52,5 +47,3 @@ tags:
   # Tests that represent a case of undesirable JS interop behavior that's
   # either unavoidable or exists as a tradeoff for improved behavior in other cases.
   js-interop-tradeoff: {}
-  # Tests for behavior that's only valid in Dart 2, and does not apply to Dart 3.
-  dart-2-only: {}
diff --git a/lib/component_base.dart b/lib/component_base.dart
@@ -14,4 +14,17 @@
 
 library over_react.component_base;
 
-export 'src/component_declaration/component_base.dart';
+import 'src/component_declaration/component_base.dart' as cb;
+
+export 'src/component_declaration/component_base.dart' hide PropsMapViewMixin, StateMapViewMixin, MapViewMixin;
+
+// Typedefs instead of deprecating the export to work around message not showing: https://github.com/dart-lang/sdk/issues/52163
+
+@Deprecated('Not for public use. Will be removed in a future major release.')
+typedef PropsMapViewMixin = cb.PropsMapViewMixin;
+
+@Deprecated('Not for public use. Will be removed in a future major release.')
+typedef StateMapViewMixin = cb.StateMapViewMixin;
+
+@Deprecated('Not for public use. Will be removed in a future major release.')
+typedef MapViewMixin = cb.MapViewMixin;
diff --git a/lib/src/builder/codegen.dart b/lib/src/builder/codegen.dart
@@ -57,8 +57,6 @@ class ImplGenerator {
       case DeclarationType.stateMixinDeclaration:
         _generateStateMixin(declaration as StateMixinDeclaration);
         break;
-      default:
-        throw ArgumentError('Unhandled declaration type: $declaration');
     }
   }
 

diff --git a/lib/src/builder/parsing/members/props_and_state_util.dart b/lib/src/builder/parsing/members/props_and_state_util.dart
@@ -23,7 +23,7 @@ extension on String {
 
 /// A mixin containing getters that can be used to facilitate runtime [String] checks
 /// for a props and state class.
-abstract class PropsStateStringHelpers {
+mixin PropsStateStringHelpers {
   bool get isProps;
   String get propsOrStateString => isProps ? 'props' : 'state';
   String get propsOrStateStringCapitalized => propsOrStateString.capitalize();
@@ -39,15 +39,15 @@ abstract class PropsStateStringHelpers {
   RegExp get propsOrStateMixinNamePattern =>
       isProps ? propsMixinNamePattern : stateMixinNamePattern;
 
-  factory PropsStateStringHelpers.props() => _PropsStateStringHelpersImpl(isProps: true);
-  factory PropsStateStringHelpers.state() => _PropsStateStringHelpersImpl(isProps: false);
+  static PropsStateStringHelpers props() => const _PropsStateStringHelpersImpl(isProps: true);
+  static PropsStateStringHelpers state() => const _PropsStateStringHelpersImpl(isProps: false);
 }
 
 class _PropsStateStringHelpersImpl extends Object with PropsStateStringHelpers {
   @override
   final bool isProps;
 
-  _PropsStateStringHelpersImpl({required this.isProps});
+  const _PropsStateStringHelpersImpl({required this.isProps});
 }
 
 /// Uses [InstantiatedMeta] to analyze [node] and determine the proper annotation.

diff --git a/lib/src/component/_deprecated/abstract_transition_props.dart b/lib/src/component/_deprecated/abstract_transition_props.dart
@@ -28,7 +28,7 @@ part 'abstract_transition_props.over_react.g.dart';
 ///     <https://github.com/Workiva/over_react_codemod/blob/71e5713ec6c256ddaf7c616ff9d6d26d77bb8f25/README.md#dart-1-to-dart-2-codemod>
 /// 2. to provide forwards-compatibility and allow this to be mixed into mixin-based component props
 @Deprecated('Use the `AbstractTransitionProps` mixin exported from `package:over_react/components.dart` instead. Will be removed in the 4.0.0 release.')
-abstract class $TransitionPropsMixin {
+mixin $TransitionPropsMixin {
   static const PropsMeta meta = _$metaForTransitionPropsMixin;
 }
 

diff --git a/lib/src/component/_deprecated/error_boundary_mixins.dart b/lib/src/component/_deprecated/error_boundary_mixins.dart
@@ -45,7 +45,7 @@ mixin LegacyErrorBoundaryApi<T extends ErrorBoundaryPropsMixin, S extends ErrorB
 /// 1. to allow for consumers which have used the --backwards-compat flag with over_react_codemod to statically analyze:
 ///     <https://github.com/Workiva/over_react_codemod/blob/71e5713ec6c256ddaf7c616ff9d6d26d77bb8f25/README.md#dart-1-to-dart-2-codemod>
 /// 2. to provide forwards-compatibility and allow this to be mixed into mixin-based component props
-abstract class $ErrorBoundaryPropsMixin {
+mixin $ErrorBoundaryPropsMixin {
   static const PropsMeta meta = _$metaForErrorBoundaryPropsMixin;
 }
 
@@ -152,7 +152,7 @@ abstract class _$ErrorBoundaryPropsMixin implements UiProps {
 /// 1. to allow for consumers which have used the --backwards-compat flag with over_react_codemod to statically analyze:
 ///     <https://github.com/Workiva/over_react_codemod/blob/71e5713ec6c256ddaf7c616ff9d6d26d77bb8f25/README.md#dart-1-to-dart-2-codemod>
 /// 2. to provide forwards-compatibility and allow this to be mixed into mixin-based component props
-abstract class $ErrorBoundaryStateMixin {
+mixin $ErrorBoundaryStateMixin {
   static const StateMeta meta = _$metaForErrorBoundaryStateMixin;
 }
 

diff --git a/lib/src/component/_deprecated/resize_sensor.dart b/lib/src/component/_deprecated/resize_sensor.dart
@@ -86,7 +86,7 @@ UiFactory<ResizeSensorProps> ResizeSensor = _$ResizeSensor;
 ///     <https://github.com/Workiva/over_react_codemod/blob/71e5713ec6c256ddaf7c616ff9d6d26d77bb8f25/README.md#dart-1-to-dart-2-codemod>
 /// 2. to provide forwards-compatibility and allow this to be mixed into mixin-based component props
 @Deprecated('Use the `ResizeSensorProps` mixin exported from `package:over_react/components.dart` instead. Will be removed in the 4.0.0 release of over_react.')
-abstract class $ResizeSensorPropsMixin {
+mixin $ResizeSensorPropsMixin {
   static const PropsMeta meta = _$metaForResizeSensorPropsMixin;
 }
 

diff --git a/lib/src/component/aria_mixin.dart b/lib/src/component/aria_mixin.dart
@@ -28,7 +28,7 @@ part 'aria_mixin.over_react.g.dart';
 /// 1. to allow for consumers which have used the --backwards-compat flag with over_react_codemod to statically analyze:
 ///     <https://github.com/Workiva/over_react_codemod/blob/71e5713ec6c256ddaf7c616ff9d6d26d77bb8f25/README.md#dart-1-to-dart-2-codemod>
 /// 2. to provide forwards-compatibility and allow this to be mixed into mixin-based component props
-abstract class $AriaPropsMixin {
+mixin $AriaPropsMixin {
   @Deprecated('This API is for use only within generated code.'
       ' Do not reference it in your code, as it may change at any time.')
   static const PropsMeta meta = _$metaForAriaPropsMixin;

diff --git a/lib/src/component/prop_mixins.dart b/lib/src/component/prop_mixins.dart
@@ -33,7 +33,7 @@ part 'prop_mixins.over_react.g.dart';
 /// 1. to allow for consumers which have used the --backwards-compat flag with over_react_codemod to statically analyze:
 ///     <https://github.com/Workiva/over_react_codemod/blob/71e5713ec6c256ddaf7c616ff9d6d26d77bb8f25/README.md#dart-1-to-dart-2-codemod>
 /// 2. to provide forwards-compatibility and allow this to be mixed into mixin-based component props
-abstract class $ReactPropsMixin {
+mixin $ReactPropsMixin {
   @Deprecated('This API is for use only within generated code.'
       ' Do not reference it in your code, as it may change at any time.')
   static const PropsMeta meta = _$metaForReactPropsMixin;
@@ -98,7 +98,7 @@ abstract class _$ReactPropsMixin {
 /// 1. to allow for consumers which have used the --backwards-compat flag with over_react_codemod to statically analyze:
 ///     <https://github.com/Workiva/over_react_codemod/blob/71e5713ec6c256ddaf7c616ff9d6d26d77bb8f25/README.md#dart-1-to-dart-2-codemod>
 /// 2. to provide forwards-compatibility and allow this to be mixed into mixin-based component props
-abstract class $DomPropsMixin {
+mixin $DomPropsMixin {
   @Deprecated('This API is for use only within generated code.'
       ' Do not reference it in your code, as it may change at any time.')
   static const PropsMeta meta = _$metaForDomPropsMixin;
@@ -209,7 +209,7 @@ abstract class _$DomPropsMixin {
 /// 1. to allow for consumers which have used the --backwards-compat flag with over_react_codemod to statically analyze:
 ///     <https://github.com/Workiva/over_react_codemod/blob/71e5713ec6c256ddaf7c616ff9d6d26d77bb8f25/README.md#dart-1-to-dart-2-codemod>
 /// 2. to provide forwards-compatibility and allow this to be mixed into mixin-based component props
-abstract class $SvgPropsMixin {
+mixin $SvgPropsMixin {
   @Deprecated('This API is for use only within generated code.'
       ' Do not reference it in your code, as it may change at any time.')
   static const PropsMeta meta = _$metaForSvgPropsMixin;
@@ -256,7 +256,7 @@ abstract class _$SvgPropsMixin {
 /// 1. to allow for consumers which have used the --backwards-compat flag with over_react_codemod to statically analyze:
 ///     <https://github.com/Workiva/over_react_codemod/blob/71e5713ec6c256ddaf7c616ff9d6d26d77bb8f25/README.md#dart-1-to-dart-2-codemod>
 /// 2. to provide forwards-compatibility and allow this to be mixed into mixin-based component props
-abstract class $UbiquitousDomPropsMixin {
+mixin $UbiquitousDomPropsMixin {
   @Deprecated('This API is for use only within generated code.'
       ' Do not reference it in your code, as it may change at any time.')
   static const PropsMeta meta = _$metaForUbiquitousDomPropsMixin;

diff --git a/lib/src/component/resize_sensor.dart b/lib/src/component/resize_sensor.dart
@@ -393,7 +393,7 @@ class ResizeSensorEvent {
 }
 
 /// A mixin that makes it easier to manage animation frames within a React component lifecycle.
-class SafeAnimationFrameMixin {
+mixin SafeAnimationFrameMixin {
   /// The ids of the pending animation frames.
   final _animationFrameIds = <int>[];
 

diff --git a/lib/src/component_declaration/builder_helpers.dart b/lib/src/component_declaration/builder_helpers.dart
@@ -31,7 +31,7 @@ export './ui_props_self_typed_extension.dart';
 //   to-be-generated members.
 // ----------------------------------------------------------------------
 
-class GeneratedClass {
+mixin GeneratedClass {
   /// Whether this class has been generated.
   ///
   /// Used to allow certain behavior (e.g., instantiation) on generated implementation classes,

diff --git a/lib/src/component_declaration/component_base.dart b/lib/src/component_declaration/component_base.dart
@@ -723,7 +723,7 @@ abstract class _OverReactMapViewBase<K, V> {
 /// functionality to [UiProps] subclasses.
 ///
 /// > Related: [StateMapViewMixin]
-abstract class PropsMapViewMixin implements _OverReactMapViewBase {
+mixin PropsMapViewMixin on _OverReactMapViewBase {
   /// The props maintained by this builder and used passed into the component when built.
   /// In this case, it's the current MapView object.
   Map get props;
@@ -739,7 +739,7 @@ abstract class PropsMapViewMixin implements _OverReactMapViewBase {
 /// functionality to [UiState] subclasses.
 ///
 /// > Related: [PropsMapViewMixin]
-abstract class StateMapViewMixin implements _OverReactMapViewBase {
+mixin StateMapViewMixin on _OverReactMapViewBase {
   Map get state;
 
   @override
@@ -756,7 +756,7 @@ abstract class StateMapViewMixin implements _OverReactMapViewBase {
 ///
 /// For use by concrete [UiProps] and [UiState] implementations (either generated or manual),
 /// and thus must remain public.
-abstract class MapViewMixin<K, V> implements _OverReactMapViewBase<K, V>, Map<K, V> {
+mixin MapViewMixin<K, V> implements _OverReactMapViewBase<K, V>, Map<K, V> {
   @override Map<K2, V2> map<K2, V2>(MapEntry<K2, V2> Function(K key, V value) f) => _map.map<K2, V2>(f);
   @override Iterable<MapEntry<K, V>> get entries => _map.entries;
   @override void addEntries(Iterable<MapEntry<K, V>> newEntries) => _map.addEntries(newEntries);

diff --git a/lib/src/over_react_redux/over_react_flux.dart b/lib/src/over_react_redux/over_react_flux.dart
@@ -32,7 +32,7 @@ part 'over_react_flux.over_react.g.dart';
 /// 1. to allow for consumers which have used the --backwards-compat flag with over_react_codemod to statically analyze:
 ///     <https://github.com/Workiva/over_react_codemod/blob/71e5713ec6c256ddaf7c616ff9d6d26d77bb8f25/README.md#dart-1-to-dart-2-codemod>
 /// 2. to provide forwards-compatibility and allow this to be mixed into mixin-based component props
-abstract class $ConnectFluxPropsMixin {
+mixin $ConnectFluxPropsMixin {
   @Deprecated('This API is for use only within generated code.'
       ' Do not reference it in your code, as it may change at any time.')
   static const PropsMeta meta = _$metaForConnectFluxPropsMixin;

diff --git a/lib/src/over_react_redux/over_react_redux.dart b/lib/src/over_react_redux/over_react_redux.dart
@@ -39,7 +39,7 @@ part 'over_react_redux.over_react.g.dart';
 /// 1. to allow for consumers which have used the --backwards-compat flag with over_react_codemod to statically analyze:
 ///     <https://github.com/Workiva/over_react_codemod/blob/71e5713ec6c256ddaf7c616ff9d6d26d77bb8f25/README.md#dart-1-to-dart-2-codemod>
 /// 2. to provide forwards-compatibility and allow this to be mixed into mixin-based component props
-abstract class $ConnectPropsMixin {
+mixin $ConnectPropsMixin {
   @Deprecated('This API is for use only within generated code.'
       ' Do not reference it in your code, as it may change at any time.')
   static const PropsMeta meta = _$metaForConnectPropsMixin;