Change min Dart SDK constraint to track actual version (#88743)

packages/flutter_tools/lib/src/cache.dart

@@ -371,6 +371,22 @@ class Cache {
   }
   String? _dartSdkVersion;
 
+  /// The current version of Dart used to build Flutter and run the tool.
+  String get dartSdkBuild {
+    if (_dartSdkBuild == null) {
+      // Make the version string more customer-friendly.
+      // Changes '2.1.0-dev.8.0.flutter-4312ae32' to '2.1.0 (build 2.1.0-dev.8.0 4312ae32)'
+      final String justVersion = _platform.version.split(' ')[0];
+      _dartSdkBuild = justVersion.replaceFirstMapped(RegExp(r'(\d+\.\d+\.\d+)(.+)'), (Match match) {
+        final String noFlutter = match[2]!.replaceAll('.flutter-', ' ');
+        return '${match[1]}$noFlutter';
+      });
+    }
+    return _dartSdkBuild!;
+  }
+  String? _dartSdkBuild;
+
+
   /// The current version of the Flutter engine the flutter tool will download.
   String get engineRevision {
     _engineRevision ??= getVersionFor('engine');

packages/flutter_tools/lib/src/commands/create.dart

@@ -230,6 +230,8 @@ class CreateCommand extends CreateBase {
       );
     }
 
+    final String dartSdk = globals.cache.dartSdkBuild;
+
     final Map<String, Object> templateContext = createTemplateContext(
       organization: organization,
       projectName: projectName,
@@ -246,7 +248,7 @@ class CreateCommand extends CreateBase {
       windows: featureFlags.isWindowsEnabled && platforms.contains('windows'),
       windowsUwp: featureFlags.isWindowsUwpEnabled && platforms.contains('winuwp'),
       // Enable null safety everywhere.
-      dartSdkVersionBounds: '">=2.12.0 <3.0.0"',
+      dartSdkVersionBounds: '">=$dartSdk <3.0.0"',
       implementationTests: boolArg('implementation-tests'),
     );
 

packages/flutter_tools/test/general.shard/cache_test.dart

@@ -16,6 +16,7 @@ import 'package:flutter_tools/src/base/platform.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/dart/pub.dart';
 import 'package:flutter_tools/src/flutter_cache.dart';
+import 'package:flutter_tools/src/globals_null_migrated.dart' as globals;
 import 'package:meta/meta.dart';
 import 'package:test/fake.dart';
 
@@ -864,6 +865,15 @@ void main() {
     expect(pub.calledGet, 1);
   });
 
+  // Check that the build number matches the format documented here:
+  // https://dart.dev/get-dart#release-channels
+  testUsingContext('Check current Dart SDK build number', () async {
+    final String currentDartSdkVersion = globals.cache.dartSdkBuild;
+    final RegExp dartSdkVersionFormat = RegExp(r'\d+\.\d+\.\d+(?:-\S+)?');
+
+    expect(dartSdkVersionFormat.allMatches(currentDartSdkVersion).length, 1,);
+  });
+
   group('AndroidMavenArtifacts', () {
     MemoryFileSystem memoryFileSystem;
     Cache cache;