Improve error message for type mismatch in Navigator.pop and maybePop.#186571
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This pull request introduces a debug-time type check for Navigator results by adding the _debugCheckCanConsumeResult method to the Route class and integrating it into pop and maybePop. This change aims to provide clearer error messages when a route is popped with a mismatched result type. Feedback suggests using _lastRouteEntryWhereOrNull instead of lastWhere in the pop method to prevent a potential StateError if the navigation history is empty and to ensure consistency with the maybePop implementation.
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justinmc
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May 15, 2026
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LGTM minus a comment from Gemini. Thanks for making Flutter's error messages better!
navaronbracke
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May 15, 2026
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Addressed the review comments:
@justinmc @navaronbracke could you please take another look? |
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justinmc
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May 18, 2026
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LGTM 👍 assuming the analyzer failure is fixed and tests pass.
navaronbracke
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May 18, 2026
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LGTM, modulo some typo fixes and something worth looking at in relation to the assert example
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Linux analyze is failing on formatting The Mac_x64 tool_tests_commands hit a crash that looks unrelated to your change, though (maybe rebase after fixing formatting?) Windows framework_tests_misc seems to have been terminated on the bot? |
victorsanni
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May 18, 2026
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navaronbracke
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May 19, 2026
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autosubmit label was removed for flutter/flutter/186571, because - The status or check suite Google testing has failed. Please fix the issues identified (or deflake) before re-applying this label. |
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autosubmit label was removed for flutter/flutter/186571, because - The status or check suite Mac_x64 tool_tests_commands has failed. Please fix the issues identified (or deflake) before re-applying this label. |
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autosubmit label was removed for flutter/flutter/186571, because - The status or check suite Linux firebase_release_smoke_test has failed. Please fix the issues identified (or deflake) before re-applying this label. |
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…11832) Manual roll requested by tarrinneal@google.com flutter/flutter@701665b...2ba5420 2026-06-03 engine-flutter-autoroll@skia.org Roll Packages from 818b310 to b11504f (8 revisions) (flutter/flutter#187511) 2026-06-03 mdebbar@google.com Add new file patterns for team-web labeler (flutter/flutter#187397) 2026-06-03 engine-flutter-autoroll@skia.org Roll Skia from 279b17fe9fc1 to d625048c853a (12 revisions) (flutter/flutter#187483) 2026-06-03 chris@bracken.jp [SwiftPM] Fix prefer_initializing_formals lint (flutter/flutter#187502) 2026-06-03 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from q27k7_um1GvVrySZS... to ap7MhLX4TdpWRrLS_... (flutter/flutter#187478) 2026-06-03 bkonyi@google.com [SwiftPM] Fix concurrent directory/file/symlink creation crashes (flutter/flutter#186953) 2026-06-03 flar@google.com [Impeller] Fix positioning of text shadow masks (flutter/flutter#187460) 2026-06-02 burak.karahan@mail.ru Remove Material imports from painting tests (flutter/flutter#186937) 2026-06-02 awolff@google.com Add android_hardware_smoke_test integration tests (flutter/flutter#187130) 2026-06-02 137456488+flutter-pub-roller-bot@users.noreply.github.com Roll pub packages (flutter/flutter#187471) 2026-06-02 pq@users.noreply.github.com [flutter tool] propagate analytics env to sub-tools (flutter/flutter#186780) 2026-06-02 30870216+gaaclarke@users.noreply.github.com Adds macro for fragment shaders to support flutter <= 3.44 (flutter/flutter#187316) 2026-06-02 116356835+AbdeMohlbi@users.noreply.github.com Small clean-up in different java files under `engine/src/flutter/shell/platform/android/io/flutter/embedding/engine/` (flutter/flutter#186631) 2026-06-02 1961493+harryterkelsen@users.noreply.github.com refactor(web): Unify ui.Path code for CanvasKit and Skwasm (flutter/flutter#187331) 2026-06-02 engine-flutter-autoroll@skia.org Roll Packages from f5d50ca to 818b310 (2 revisions) (flutter/flutter#187441) 2026-06-02 faheemabbas766@gmail.com Allow selecting multi-digit device options (flutter/flutter#186184) 2026-06-02 puneetkukreja98@gmail.com Improve error message for type mismatch in Navigator.pop and maybePop. (flutter/flutter#186571) 2026-06-02 sanaullah.383@hotmail.com Remove semantics_tester import from material_button_test.dart (flutter/flutter#184807) 2026-06-02 bkonyi@google.com [flutter_tools] Refactor hostPlatform to use Abi.current() (flutter/flutter#185369) 2026-06-02 mvincentong@gmail.com Clean up avoid_type_to_string suppressions (flutter/flutter#186869) 2026-06-02 202459002+Lukes-Lair@users.noreply.github.com Update Flutter documentation links in flutter_console.bat (flutter/flutter#187354) 2026-06-02 154381524+flutteractionsbot@users.noreply.github.com Revert "[Impeller] Allow attaching specific texture mip levels and slices" (flutter/flutter#187445) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC stuartmorgan@google.com,tarrinneal@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
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…lutter#11832) Manual roll requested by tarrinneal@google.com flutter/flutter@701665b...2ba5420 2026-06-03 engine-flutter-autoroll@skia.org Roll Packages from 818b310 to b11504f (8 revisions) (flutter/flutter#187511) 2026-06-03 mdebbar@google.com Add new file patterns for team-web labeler (flutter/flutter#187397) 2026-06-03 engine-flutter-autoroll@skia.org Roll Skia from 279b17fe9fc1 to d625048c853a (12 revisions) (flutter/flutter#187483) 2026-06-03 chris@bracken.jp [SwiftPM] Fix prefer_initializing_formals lint (flutter/flutter#187502) 2026-06-03 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from q27k7_um1GvVrySZS... to ap7MhLX4TdpWRrLS_... (flutter/flutter#187478) 2026-06-03 bkonyi@google.com [SwiftPM] Fix concurrent directory/file/symlink creation crashes (flutter/flutter#186953) 2026-06-03 flar@google.com [Impeller] Fix positioning of text shadow masks (flutter/flutter#187460) 2026-06-02 burak.karahan@mail.ru Remove Material imports from painting tests (flutter/flutter#186937) 2026-06-02 awolff@google.com Add android_hardware_smoke_test integration tests (flutter/flutter#187130) 2026-06-02 137456488+flutter-pub-roller-bot@users.noreply.github.com Roll pub packages (flutter/flutter#187471) 2026-06-02 pq@users.noreply.github.com [flutter tool] propagate analytics env to sub-tools (flutter/flutter#186780) 2026-06-02 30870216+gaaclarke@users.noreply.github.com Adds macro for fragment shaders to support flutter <= 3.44 (flutter/flutter#187316) 2026-06-02 116356835+AbdeMohlbi@users.noreply.github.com Small clean-up in different java files under `engine/src/flutter/shell/platform/android/io/flutter/embedding/engine/` (flutter/flutter#186631) 2026-06-02 1961493+harryterkelsen@users.noreply.github.com refactor(web): Unify ui.Path code for CanvasKit and Skwasm (flutter/flutter#187331) 2026-06-02 engine-flutter-autoroll@skia.org Roll Packages from f5d50ca to 818b310 (2 revisions) (flutter/flutter#187441) 2026-06-02 faheemabbas766@gmail.com Allow selecting multi-digit device options (flutter/flutter#186184) 2026-06-02 puneetkukreja98@gmail.com Improve error message for type mismatch in Navigator.pop and maybePop. (flutter/flutter#186571) 2026-06-02 sanaullah.383@hotmail.com Remove semantics_tester import from material_button_test.dart (flutter/flutter#184807) 2026-06-02 bkonyi@google.com [flutter_tools] Refactor hostPlatform to use Abi.current() (flutter/flutter#185369) 2026-06-02 mvincentong@gmail.com Clean up avoid_type_to_string suppressions (flutter/flutter#186869) 2026-06-02 202459002+Lukes-Lair@users.noreply.github.com Update Flutter documentation links in flutter_console.bat (flutter/flutter#187354) 2026-06-02 154381524+flutteractionsbot@users.noreply.github.com Revert "[Impeller] Allow attaching specific texture mip levels and slices" (flutter/flutter#187445) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC stuartmorgan@google.com,tarrinneal@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
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flutter#186571) <!-- Thanks for filing a pull request! Reviewers are typically assigned within a week of filing a request. To learn more about code review, see our documentation on Tree Hygiene: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md --> **Context** Currently, if a developer opens a strongly-typed route (such as `showDialog<Null>`) but accidentally pops it with an incompatible value (like `Navigator.pop(context, "CANCEL")`). Because the generic types do not match, the Dart runtime instantly throws a cryptic native `TypeError` (e.g., `type 'String' is not a subtype of type 'Null'`) without any context about which route or widget caused it. **Changes** * Added a `_debugCheckCanConsumeResult` helper to `Route<T>` that proactively validates `result is T?`. * Intercepts `Navigator.pop`, `Navigator.maybePop`, before they modify the stack or lock the Navigator. * If a type mismatch occurs, it now throws a highly descriptive `FlutterError` that pinpoints the exact expected type, the provided type, and the specific `Route` object involved. * Added comprehensive tests to `navigator_test.dart` to verify this behavior for `pop` and `maybePop` using a real-world `showDialog` scenario. Fixes flutter#16987 ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [AI contribution guidelines] and understand my responsibilities, or I am not using AI tools. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [ ] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord]. If this change needs to override an active code freeze, provide a comment explaining why. The code freeze workflow can be overridden by code reviewers. See pinned issues for any active code freezes with guidance. **Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed. <!-- Links --> [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [AI contribution guidelines]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#ai-contribution-guidelines [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md --------- Co-authored-by: chunhtai <47866232+chunhtai@users.noreply.github.com> Co-authored-by: Victor Sanni <victorsanniay@gmail.com>
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Context
Currently, if a developer opens a strongly-typed route (such as
showDialog<Null>) but accidentally pops it with an incompatible value (likeNavigator.pop(context, "CANCEL")). Because the generic types do not match, the Dart runtime instantly throws a cryptic nativeTypeError(e.g.,type 'String' is not a subtype of type 'Null') without any context about which route or widget caused it.Changes
_debugCheckCanConsumeResulthelper toRoute<T>that proactively validatesresult is T?.Navigator.pop,Navigator.maybePop, before they modify the stack or lock the Navigator.FlutterErrorthat pinpoints the exact expected type, the provided type, and the specificRouteobject involved.navigator_test.dartto verify this behavior forpopandmaybePopusing a real-worldshowDialogscenario.Fixes #16987
Pre-launch Checklist
///).If you need help, consider asking for advice on the #hackers-new channel on Discord.
If this change needs to override an active code freeze, provide a comment explaining why. The code freeze workflow can be overridden by code reviewers. See pinned issues for any active code freezes with guidance.
Note: The Flutter team is currently trialing the use of Gemini Code Assist for GitHub. Comments from the
gemini-code-assistbot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed.