[flutter_tools] Intercept prohibited hot reloads in widget preview and trigger hot restart - #193447

…eview and trigger hot restart (flutter#193968)

Reverts: [[flutter_tools] Intercept prohibited hot reloads in widget
preview and trigger hot
restart](flutter#193447)

Initiated by: @bkonyi

Reason for reverting: conflicting changes with
flutter#192831 are causing failures due
to concurrent merge

Original PR Author: @bkonyi

Reviewed By: @srawlins

The original PR description is provided below:

When hot reload fails due to unsupported changes (such as class
hierarchy modifications, global initializer changes, or file
additions/deletions) in `flutter widget-preview`, automatically fall
back to a hot restart instead of leaving the previewer in a failed
reload state.

### Changes
- **`ResidentWebRunner`**: Attach `updateFSReport` to the failed
`OperationResult` when `_updateDevFS` fails so callers can inspect
`UpdateFSReport.hotReloadRejected`.
- **`WidgetPreviewStartCommand`**: Introduce `handleReload()` (invoked
inside `_triggerReload` for `.hotReload` requests so the fallback
remains serialized with other reload and restart requests, and add a
`@visibleForTesting` `widgetPreviewApp` setter), which checks if
`restart()` returned an `OperationResult` with
`UpdateFSReport(hotReloadRejected: true)`. When rejected, log a status
message (`kHotReloadRejectedMessage`) and invoke `restart(fullRestart:
true)`.

Fixes flutter#192697

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [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].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

<!-- Links -->
[Contributor Guide]:
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[Tree Hygiene]:
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[test-exempt]:
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[Flutter Style Guide]:
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[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/
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
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[Data Driven Fixes]:
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…d trigger hot restart (flutter#193447)

When hot reload fails due to unsupported changes (such as class
hierarchy modifications, global initializer changes, or file
additions/deletions) in `flutter widget-preview`, automatically fall
back to a hot restart instead of leaving the previewer in a failed
reload state.

### Changes
- **`ResidentWebRunner`**: Attach `updateFSReport` to the failed
`OperationResult` when `_updateDevFS` fails so callers can inspect
`UpdateFSReport.hotReloadRejected`.
- **`WidgetPreviewStartCommand`**: Introduce `handleReload()` (invoked
inside `_triggerReload` for `.hotReload` requests so the fallback
remains serialized with other reload and restart requests, and add a
`@visibleForTesting` `widgetPreviewApp` setter), which checks if
`restart()` returned an `OperationResult` with
`UpdateFSReport(hotReloadRejected: true)`. When rejected, log a status
message (`kHotReloadRejectedMessage`) and invoke `restart(fullRestart:
true)`.

Fixes flutter#192697

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [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].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[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/
[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

…eview and trigger hot restart (flutter#193968)

Reverts: [[flutter_tools] Intercept prohibited hot reloads in widget
preview and trigger hot
restart](flutter#193447)

Initiated by: @bkonyi

Reason for reverting: conflicting changes with
flutter#192831 are causing failures due
to concurrent merge

Original PR Author: @bkonyi

Reviewed By: @srawlins

The original PR description is provided below:

When hot reload fails due to unsupported changes (such as class
hierarchy modifications, global initializer changes, or file
additions/deletions) in `flutter widget-preview`, automatically fall
back to a hot restart instead of leaving the previewer in a failed
reload state.

### Changes
- **`ResidentWebRunner`**: Attach `updateFSReport` to the failed
`OperationResult` when `_updateDevFS` fails so callers can inspect
`UpdateFSReport.hotReloadRejected`.
- **`WidgetPreviewStartCommand`**: Introduce `handleReload()` (invoked
inside `_triggerReload` for `.hotReload` requests so the fallback
remains serialized with other reload and restart requests, and add a
`@visibleForTesting` `widgetPreviewApp` setter), which checks if
`restart()` returned an `OperationResult` with
`UpdateFSReport(hotReloadRejected: true)`. When rejected, log a status
message (`kHotReloadRejectedMessage`) and invoke `restart(fullRestart:
true)`.

Fixes flutter#192697

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [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].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[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/
[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

…sts that run the real pub

The hermetic commands shard had left out nine files and the permeable
half entirely: their tests resolve a project of their own with the real
pub (the widget_preview tests' scaffold, `flutter create`'s projects,
`flutter pub get` on plugins), and pub wants a Flutter SDK -- not just the
Dart SDK and engine stamps the general shard's facsimile under bin/cache
already had. This lays the rest of pub's view of an SDK in the runfiles
tree, and a pub cache of what the projects reach, so no test downloads a
package:

* `pub_cache(name, roots, dev_roots, without)` (dart/pub.bzl): the hosted
  packages of a closure, laid as a pub cache
  (`hosted/pub.dev/<name>-<version>/` plus the `hosted-hashes` sha256 pub
  checks) from the pinned sources `@pub` already fetches. dart_test's new
  `pub_cache` attribute symlinks it under the runfiles `.pub-cache` and the
  launcher exports PUB_CACHE. pub still asks pub.dev which versions exist
  unless it runs `--offline` (the tests do not), so such a shard has the
  network; it downloads nothing it finds in the cache (one package --
  webview_flutter_web, outside the workspace's lock -- it does fetch).
* `bin/cache/flutter.version.json` (bin/internal: `flutter_version_json`):
  pub's Flutter SDK source reads `flutterVersion` from it and checks it
  against the packages' `flutter:` constraints (leak_tracker_flutter_testing
  wants >=3.18); the tool parses `frameworkVersion` as a git tag. Fixed
  words again: 999.0.0-0.0.pre, the version every constraint allows.
* The SDK packages under FLUTTER_ROOT/packages (flutter, flutter_test,
  flutter_localizations, flutter_driver, integration_test,
  fuchsia_remote_debug_protocol and a new BUILD for flutter_web_plugins),
  the workspace's pubspec.yaml and pubspec.lock (`flutter create` reads
  the SDK's lock), and the engine's sky_engine package under
  `bin/cache/pkg/sky_engine` (the analyzer resolves dart:ui from it):
  `assembled_directory(contents, prefix)` in local_engine.bzl is the
  `install`/`local_engine` assembly as a rule of its own, and
  `//engine/src/flutter/sky/packages/sky_engine:package` (a converter
  appendix) lays dart_pkg's directory and the copied libraries as GN's
  `gen/dart-pkg/sky_engine`.
* `<dart-sdk>/version` in the SDK overlay's `dart` filegroup: the analyzer
  (`AnalysisContextCollection` with `sdkPath`) reads it; six widget_preview
  tests needed only this.
* `@gradle_wrapper` (flutter_sdk_cache.bzl, from bin/internal's pin):
  `flutter create` copies `bin/cache/artifacts/gradle_wrapper` into an
  Android project.
* `dart_tests(large = [...])`, as flutter_tests has it: preview_detector_test,
  preview_detector_workspace_test and preview_code_generator_test take
  minutes on a loaded machine (the first timed out at 300 s).
* //bin:BUILD.bazel exports the Windows entrypoint scripts as text
  (script_test reads them for what they must not do); the Unix ones stay
  out on purpose -- a test that finds bin/flutter spawns it, and the script
  bootstraps the tool from the network. integration_test's `sources` gain
  its Android embedding: the package is a plugin, and the tool reads the
  main class when a project that depends on it resolves.

`//packages/flutter_tools:commands_shard_hermetic` is now the whole
directory (67 files, up from 58); `commands_shard_permeable` is new (8 of
11: create_test analyzes, resolves and tests the projects it creates with
bin/cache/flutter_tools.snapshot and icon_tree_shaker_test spawns
bin/flutter -- the built tool, which a later change can lay in the
facsimile from Bazel's own compile; widget_preview_test does not compile
at this checkout, flutter#192831 and flutter#193447 crossed and upstream reverted the
latter in flutter#193968). Both are in `//:tool_tests`. The README's tests
section describes the facsimile.

Measured:
  bazel test //packages/flutter_tools:commands_shard_hermetic \
             //packages/flutter_tools:commands_shard_permeable
    75 of 75 targets pass; 1,140 cases passed, 6 skipped
  dart test (FLUTTER_ROOT set, -j 4) over the same 75 files: 1,140 + 6
  bazel test //:tool_tests //:dart_tests: 406 of 406 targets pass
  gn_to_bazel --check clean; converter tests 231, bazel_tools tests 43.