[ci] Add initial LUCI legacy analysis (#4428)

Adds new legacy analysis targets to LUCI in bringup mode.

Also updates the repo tooling to use a Flutter->Dart version mapping instead of having to separately maintain a Dart version, now that we already have such a map in the tool anyway.

Part of https://github.com/flutter/flutter/issues/114373

.ci.yaml

@@ -228,6 +228,24 @@ targets:
       channel: stable
       version_file: flutter_stable.version
 
+  # Analyze with the previous stable (N-1) and the stable before that (N-2). The
+  # versions in `channel` should be updated after a new major stable release.
+  - name: Linux analyze_legacy N-1
+    bringup: true # New target
+    recipe: packages/packages
+    timeout: 30
+    properties:
+      target_file: analyze_legacy.yaml
+      channel: "3.7.12"
+
+  - name: Linux analyze_legacy N-2
+    bringup: true # New target
+    recipe: packages/packages
+    timeout: 30
+    properties:
+      target_file: analyze_legacy.yaml
+      channel: "3.3.10"
+
   - name: Linux_android custom_package_tests master
     recipe: packages/packages
     timeout: 30

.ci/scripts/analyze_legacy.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+set -e
+
+# Allow analyzing packages that use a dev dependency with a higher minimum
+# Flutter/Dart version than the package itself. Non-client code doesn't need to
+# work in legacy versions.
+#
+# This requires the --lib-only flag below.
+./script/tool_runner.sh remove-dev-dependencies
+
+# This uses --run-on-dirty-packages rather than --packages-for-branch
+# since only the packages changed by 'make-deps-path-based' need to be
+# re-checked.
+./script/tool_runner.sh analyze --lib-only \
+    --skip-if-not-supporting-flutter-version="$CHANNEL" \
+    --custom-analysis=script/configs/custom_analysis.yaml
+
+# Restore the tree to a clean state, to avoid accidental issues if
+# other script steps are added to the enclosing task.
+git checkout .

.ci/targets/analyze.yaml

@@ -12,4 +12,4 @@ tasks:
     # the changes won't break analysis of other packages in the respository
     # that depend on it.
   - name: analyze - pathified
-    script: .ci/scripts/pathified_analyze.sh
+    script: .ci/scripts/analyze_pathified.sh

.ci/targets/analyze_legacy.yaml

@@ -0,0 +1,11 @@
+tasks:
+  - name: prepare tool
+    script: .ci/scripts/prepare_tool.sh
+  # Does a sanity check that packages at least pass analysis on the N-1 and N-2
+  # versions of Flutter stable if the package claims to support that version.
+  # This is to minimize accidentally making changes that break old versions
+  # (which we don't commit to supporting, but don't want to actively break)
+  # without updating the constraints.
+  # See https://github.com/flutter/flutter/wiki/Contributing-to-Plugins-and-Packages#supported-flutter-versions
+  - name: analyze - legacy
+    script: .ci/scripts/analyze_legacy.sh

.ci/targets/repo_checks.yaml

@@ -10,7 +10,7 @@ tasks:
     args: ["license-check"]
     always: true
     # The major and minor version here should match the lowest version analyzed
-    # in legacy version analysis (currently .cirrus.yaml legacy_version_analyze).
+    # in legacy version analysis (.ci.yaml analyze_legacy).
   - name: pubspec validation
     script: script/tool_runner.sh
     args:

.cirrus.yml

@@ -96,10 +96,8 @@ task:
         # Change the arguments to pubspec-check when changing these values.
         env:
           CHANNEL: "3.7.12"
-          DART_VERSION: "2.17.6"
         env:
           CHANNEL: "3.3.10"
-          DART_VERSION: "2.18.6"
       package_prep_script:
         # Allow analyzing packages that use a dev dependency with a higher
         # minimum Flutter/Dart version than the package itself.
@@ -107,7 +105,7 @@ task:
       analyze_script:
         # Only analyze lib/; non-client code doesn't need to work on
         # all supported legacy version.
-        - ./script/tool_runner.sh analyze --lib-only --skip-if-not-supporting-flutter-version="$CHANNEL" --skip-if-not-supporting-dart-version="$DART_VERSION" --custom-analysis=script/configs/custom_analysis.yaml
+        - ./script/tool_runner.sh analyze --lib-only --skip-if-not-supporting-flutter-version="$CHANNEL" --custom-analysis=script/configs/custom_analysis.yaml
     - name: readme_excerpts
       env:
         CIRRUS_CLONE_SUBMODULES: true

script/tool/lib/src/common/core.dart

@@ -44,7 +44,9 @@ final Map<Version, Version> _dartSdkForFlutterSdk = <Version, Version>{
   Version(3, 0, 0): Version(2, 17, 0),
   Version(3, 0, 5): Version(2, 17, 6),
   Version(3, 3, 0): Version(2, 18, 0),
+  Version(3, 3, 10): Version(2, 18, 6),
   Version(3, 7, 0): Version(2, 19, 0),
+  Version(3, 7, 12): Version(2, 19, 6),
   Version(3, 10, 0): Version(3, 0, 0),
 };
 

script/tool/lib/src/common/package_looping_command.dart

@@ -90,19 +90,13 @@ abstract class PackageLoopingCommand extends PackageCommand {
     argParser.addOption(
       _skipByFlutterVersionArg,
       help: 'Skip any packages that require a Flutter version newer than '
-          'the provided version.',
-    );
-    argParser.addOption(
-      _skipByDartVersionArg,
-      help: 'Skip any packages that require a Dart version newer than '
-          'the provided version.',
+          'the provided version, or a Dart version newer than the '
+          'corresponding Dart version.',
     );
   }
 
   static const String _skipByFlutterVersionArg =
       'skip-if-not-supporting-flutter-version';
-  static const String _skipByDartVersionArg =
-      'skip-if-not-supporting-dart-version';
 
   /// Packages that had at least one [logWarning] call.
   final Set<PackageEnumerationEntry> _packagesWithWarnings =
@@ -267,9 +261,9 @@ abstract class PackageLoopingCommand extends PackageCommand {
     final Version? minFlutterVersion = minFlutterVersionArg.isEmpty
         ? null
         : Version.parse(minFlutterVersionArg);
-    final String minDartVersionArg = getStringArg(_skipByDartVersionArg);
-    final Version? minDartVersion =
-        minDartVersionArg.isEmpty ? null : Version.parse(minDartVersionArg);
+    final Version? minDartVersion = minFlutterVersion == null
+        ? null
+        : getDartSdkForFlutterSdk(minFlutterVersion);
 
     final DateTime runStart = DateTime.now();
 

script/tool/test/common/package_looping_command_test.dart

@@ -373,15 +373,16 @@ void main() {
     test('skips unsupported Dart versions when requested', () async {
       final RepositoryPackage excluded = createFakePackage(
           'excluded_package', packagesDir,
-          dartConstraint: '>=2.17.0 <4.0.0');
+          dartConstraint: '>=2.18.0 <4.0.0');
       final RepositoryPackage included =
           createFakePackage('a_package', packagesDir);
 
       final TestPackageLoopingCommand command = createTestCommand(
           packageLoopingType: PackageLoopingType.includeAllSubpackages,
           hasLongOutput: false);
-      final List<String> output = await runCommand(command,
-          arguments: <String>['--skip-if-not-supporting-dart-version=2.14.0']);
+      final List<String> output = await runCommand(command, arguments: <String>[
+        '--skip-if-not-supporting-flutter-version=3.0.0' // Flutter 3.0.0 -> Dart 2.17.0
+      ]);
 
       expect(
           command.checkedPackages,
@@ -396,7 +397,7 @@ void main() {
           containsAllInOrder(<String>[
             '${_startHeadingColor}Running for a_package...$_endColor',
             '${_startHeadingColor}Running for excluded_package...$_endColor',
-            '$_startSkipColor  SKIPPING: Does not support Dart 2.14.0$_endColor',
+            '$_startSkipColor  SKIPPING: Does not support Dart 2.17.0$_endColor',
           ]));
     });
   });