Switch script/tools over to the new analysis options (#3777)

Removes the legacy analysis options override and fixes all resulting issues. This is a combination of dart fix and manual changes (mostly mechanical, but some small restructuring to address warnings more cleanly, such as creating typed structs from args when they are used repeatedly to avoid repeated casting, or making things that were unnecessarily public private).

One small opportunistic extra cleanup is that the handling of null-safety prerelease versions is removed, as any new plugin would be written null-safe from the start, so we no longer need to allow those versions.

Part of flutter/flutter#76229

script/tool/lib/src/version_check_command.dart

@@ -15,47 +15,32 @@ import 'common.dart';
 
 const String _kBaseSha = 'base-sha';
 
+/// Categories of version change types.
 enum NextVersionType {
+  /// A breaking change.
   BREAKING_MAJOR,
-  MAJOR_NULLSAFETY_PRE_RELEASE,
-  MINOR_NULLSAFETY_PRE_RELEASE,
+
+  /// A minor change (e.g., added feature).
   MINOR,
+
+  /// A bugfix change.
   PATCH,
+
+  /// The release of an existing prerelease version.
   RELEASE,
 }
 
-Version getNextNullSafetyPreRelease(Version current, Version next) {
-  String nextNullsafetyPrerelease = 'nullsafety';
-  if (current.isPreRelease &&
-      current.preRelease.first is String &&
-      current.preRelease.first == 'nullsafety') {
-    if (current.preRelease.length == 1) {
-      nextNullsafetyPrerelease = 'nullsafety.1';
-    } else if (current.preRelease.length == 2 &&
-        current.preRelease.last is int) {
-      nextNullsafetyPrerelease = 'nullsafety.${current.preRelease.last + 1}';
-    }
-  }
-  return Version(
-    next.major,
-    next.minor,
-    next.patch,
-    pre: nextNullsafetyPrerelease,
-  );
-}
-
+/// Returns the set of allowed next versions, with their change type, for
+/// [masterVersion].
+///
+/// [headVerison] is used to check whether this is a pre-1.0 version bump, as
+/// those have different semver rules.
 @visibleForTesting
 Map<Version, NextVersionType> getAllowedNextVersions(
     Version masterVersion, Version headVersion) {
-  final Version nextNullSafetyMajor =
-      getNextNullSafetyPreRelease(masterVersion, masterVersion.nextMajor);
-  final Version nextNullSafetyMinor =
-      getNextNullSafetyPreRelease(masterVersion, masterVersion.nextMinor);
   final Map<Version, NextVersionType> allowedNextVersions =
       <Version, NextVersionType>{
     masterVersion.nextMajor: NextVersionType.BREAKING_MAJOR,
-    nextNullSafetyMajor: NextVersionType.MAJOR_NULLSAFETY_PRE_RELEASE,
-    nextNullSafetyMinor: NextVersionType.MINOR_NULLSAFETY_PRE_RELEASE,
     masterVersion.nextMinor: NextVersionType.MINOR,
     masterVersion.nextPatch: NextVersionType.PATCH,
   };
@@ -65,7 +50,7 @@ Map<Version, NextVersionType> getAllowedNextVersions(
     if (masterVersion.build.isEmpty) {
       nextBuildNumber = 1;
     } else {
-      final int currentBuildNumber = masterVersion.build.first;
+      final int currentBuildNumber = masterVersion.build.first as int;
       nextBuildNumber = currentBuildNumber + 1;
     }
     final Version preReleaseVersion = Version(
@@ -80,21 +65,13 @@ Map<Version, NextVersionType> getAllowedNextVersions(
         NextVersionType.BREAKING_MAJOR;
     allowedNextVersions[masterVersion.nextPatch] = NextVersionType.MINOR;
     allowedNextVersions[preReleaseVersion] = NextVersionType.PATCH;
-
-    final Version nextNullSafetyMajor =
-        getNextNullSafetyPreRelease(masterVersion, masterVersion.nextMinor);
-    final Version nextNullSafetyMinor =
-        getNextNullSafetyPreRelease(masterVersion, masterVersion.nextPatch);
-
-    allowedNextVersions[nextNullSafetyMajor] =
-        NextVersionType.MAJOR_NULLSAFETY_PRE_RELEASE;
-    allowedNextVersions[nextNullSafetyMinor] =
-        NextVersionType.MINOR_NULLSAFETY_PRE_RELEASE;
   }
   return allowedNextVersions;
 }
 
+/// A command to validate version changes to packages.
 class VersionCheckCommand extends PluginCommand {
+  /// Creates an instance of the version check command.
   VersionCheckCommand(
     Directory packagesDir,
     FileSystem fileSystem, {
@@ -113,14 +90,13 @@ class VersionCheckCommand extends PluginCommand {
       'This command requires "pub" and "flutter" to be in your path.';
 
   @override
-  Future<Null> run() async {
-    checkSharding();
+  Future<void> run() async {
     final GitVersionFinder gitVersionFinder = await retrieveVersionFinder();
 
     final List<String> changedPubspecs =
         await gitVersionFinder.getChangedPubSpecs();
 
-    final String baseSha = argResults[_kBaseSha];
+    final String baseSha = argResults[_kBaseSha] as String;
     for (final String pubspecPath in changedPubspecs) {
       try {
         final File pubspecFile = fileSystem.file(pubspecPath);
@@ -150,7 +126,8 @@ class VersionCheckCommand extends PluginCommand {
           printErrorAndExit(errorMessage: error);
         }
 
-        bool isPlatformInterface = pubspec.name.endsWith("_platform_interface");
+        final bool isPlatformInterface =
+            pubspec.name.endsWith('_platform_interface');
         if (isPlatformInterface &&
             allowedNextVersions[headVersion] ==
                 NextVersionType.BREAKING_MAJOR) {
@@ -164,7 +141,7 @@ class VersionCheckCommand extends PluginCommand {
       }
     }
 
-    await for (Directory plugin in getPlugins()) {
+    await for (final Directory plugin in getPlugins()) {
       await _checkVersionsMatch(plugin);
     }
 
@@ -180,7 +157,7 @@ class VersionCheckCommand extends PluginCommand {
 
     final Pubspec pubspec = _tryParsePubspec(plugin);
     if (pubspec == null) {
-      final String error = 'Cannot parse version from pubspec.yaml';
+      const String error = 'Cannot parse version from pubspec.yaml';
       printErrorAndExit(errorMessage: error);
     }
     final Version fromPubspec = pubspec.version;
@@ -189,16 +166,16 @@ class VersionCheckCommand extends PluginCommand {
     final File changelog = plugin.childFile('CHANGELOG.md');
     final List<String> lines = changelog.readAsLinesSync();
     String firstLineWithText;
-    final Iterator iterator = lines.iterator;
+    final Iterator<String> iterator = lines.iterator;
     while (iterator.moveNext()) {
-      if ((iterator.current as String).trim().isNotEmpty) {
+      if (iterator.current.trim().isNotEmpty) {
         firstLineWithText = iterator.current;
         break;
       }
     }
     // Remove all leading mark down syntax from the version line.
     final String versionString = firstLineWithText.split(' ').last;
-    Version fromChangeLog = Version.parse(versionString);
+    final Version fromChangeLog = Version.parse(versionString);
     if (fromChangeLog == null) {
       final String error =
           'Cannot find version on the first line of ${plugin.path}/CHANGELOG.md';
@@ -213,14 +190,14 @@ The first version listed in CHANGELOG.md is $fromChangeLog.
 ''';
       printErrorAndExit(errorMessage: error);
     }
-    print('${packageName} passed version check');
+    print('$packageName passed version check');
   }
 
   Pubspec _tryParsePubspec(Directory package) {
     final File pubspecFile = package.childFile('pubspec.yaml');
 
     try {
-      Pubspec pubspec = Pubspec.parse(pubspecFile.readAsStringSync());
+      final Pubspec pubspec = Pubspec.parse(pubspecFile.readAsStringSync());
       if (pubspec == null) {
         final String error =
             'Failed to parse `pubspec.yaml` at ${pubspecFile.path}';