[flutter_tool] Don't crash on failed stamp file update (#49080)

packages/flutter_tools/lib/src/cache.dart

@@ -511,7 +511,16 @@ abstract class CachedArtifact extends ArtifactSet {
       }
     }
     await updateInner();
-    cache.setStampFor(stampName, version);
+    try {
+      cache.setStampFor(stampName, version);
+    } on FileSystemException catch (err) {
+      globals.printError(
+        'The new artifact "$name" was downloaded, but Flutter failed to update '
+        'its stamp file, receiving the error "$err". '
+        'Flutter can continue, but the artifact may be re-downloaded on '
+        'subsequent invocations until the problem is resolved.',
+      );
+    }
     _removeDownloadedFiles();
   }
 

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

@@ -115,6 +115,23 @@ void main() {
       ProcessManager: () => FakeProcessManager.any(),
     });
 
+    testUsingContext('Continues on failed stamp file update', () async {
+      final Directory artifactDir = globals.fs.systemTempDirectory.createTempSync('flutter_cache_test_artifact.');
+      final Directory downloadDir = globals.fs.systemTempDirectory.createTempSync('flutter_cache_test_download.');
+      when(mockCache.getArtifactDirectory(any)).thenReturn(artifactDir);
+      when(mockCache.getDownloadDir()).thenReturn(downloadDir);
+      when(mockCache.setStampFor(any, any)).thenAnswer((_) {
+        throw const FileSystemException('stamp write failed');
+      });
+      final FakeSimpleArtifact artifact = FakeSimpleArtifact(mockCache);
+      await artifact.update();
+      expect(testLogger.errorText, contains('stamp write failed'));
+    }, overrides: <Type, Generator>{
+      Cache: () => mockCache,
+      FileSystem: () => memoryFileSystem,
+      ProcessManager: () => FakeProcessManager.any(),
+    });
+
     testUsingContext('Gradle wrapper should not be up to date, if some cached artifact is not available', () {
       final GradleWrapper gradleWrapper = GradleWrapper(mockCache);
       final Directory directory = globals.fs.directory('/Applications/flutter/bin/cache');
@@ -455,6 +472,19 @@ class FakeCachedArtifact extends EngineCachedArtifact {
   List<String> getPackageDirs() => packageDirs;
 }
 
+class FakeSimpleArtifact extends CachedArtifact {
+  FakeSimpleArtifact(Cache cache) : super(
+    'fake',
+    cache,
+    DevelopmentArtifact.universal,
+  );
+
+  @override
+  Future<void> updateInner() async {
+    // nop.
+  }
+}
+
 class FakeDownloadedArtifact extends CachedArtifact {
   FakeDownloadedArtifact(this.downloadedFile, Cache cache) : super(
     'fake',