Print errors in all build modes (#69046)

dev/bots/test.dart

@@ -776,9 +776,12 @@ Future<void> _runWebUnitTests() async {
 }
 
 Future<void> _runWebIntegrationTests() async {
-  await _runWebStackTraceTest('profile');
-  await _runWebStackTraceTest('release');
+  await _runWebStackTraceTest('profile', 'lib/stack_trace.dart');
+  await _runWebStackTraceTest('release', 'lib/stack_trace.dart');
+  await _runWebStackTraceTest('profile', 'lib/framework_stack_trace.dart');
+  await _runWebStackTraceTest('release', 'lib/framework_stack_trace.dart');
   await _runWebDebugTest('lib/stack_trace.dart');
+  await _runWebDebugTest('lib/framework_stack_trace.dart');
   await _runWebDebugTest('lib/web_directory_loading.dart');
   await _runWebDebugTest('test/test.dart');
   await _runWebDebugTest('lib/null_assert_main.dart', enableNullSafety: true);
@@ -807,7 +810,7 @@ Future<void> _runWebIntegrationTests() async {
   ]);
 }
 
-Future<void> _runWebStackTraceTest(String buildMode) async {
+Future<void> _runWebStackTraceTest(String buildMode, String entrypoint) async {
   final String testAppDirectory = path.join(flutterRoot, 'dev', 'integration_tests', 'web');
   final String appBuildDirectory = path.join(testAppDirectory, 'build', 'web');
 
@@ -824,7 +827,7 @@ Future<void> _runWebStackTraceTest(String buildMode) async {
       'web',
       '--$buildMode',
       '-t',
-      'lib/stack_trace.dart',
+      entrypoint,
     ],
     workingDirectory: testAppDirectory,
     environment: <String, String>{

dev/integration_tests/web/lib/framework_stack_trace.dart

@@ -0,0 +1,96 @@
+// Copyright 2014 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.
+
+import 'dart:html' as html;
+
+import 'package:meta/dart2js.dart';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/widgets.dart';
+
+// Tests that the framework prints stack traces in all build modes.
+//
+// Regression test for https://github.com/flutter/flutter/issues/68616.
+//
+// See also `dev/integration_tests/web/lib/stack_trace.dart` that tests the
+// framework's ability to parse stack traces in all build modes.
+void main() async {
+  final StringBuffer errorMessage = StringBuffer();
+  debugPrint = (String message, { int wrapWidth }) {
+    errorMessage.writeln(message);
+  };
+
+  runApp(ThrowingWidget());
+
+  // Let the framework flush error messages.
+  await Future<void>.delayed(Duration.zero);
+
+  final StringBuffer output = StringBuffer();
+  if (_errorMessageFormattedCorrectly(errorMessage.toString())) {
+    output.writeln('--- TEST SUCCEEDED ---');
+  } else  {
+    output.writeln('--- UNEXPECTED ERROR MESSAGE FORMAT ---');
+    output.writeln(errorMessage);
+    output.writeln('--- TEST FAILED ---');
+  }
+
+  print(output);
+  html.HttpRequest.request(
+    '/test-result',
+    method: 'POST',
+    sendData: '$output',
+  );
+}
+
+bool _errorMessageFormattedCorrectly(String errorMessage) {
+  if (!errorMessage.contains('Test error message')) {
+    return false;
+  }
+
+  // In release mode symbols are minified. No sense testing the contents of the stack trace.
+  if (kReleaseMode) {
+    return true;
+  }
+
+  const List<String> expectedFunctions = <String>[
+    'topLevelFunction',
+    'secondLevelFunction',
+    'thirdLevelFunction',
+  ];
+
+  return expectedFunctions.every(errorMessage.contains);
+}
+
+class ThrowingWidget extends StatefulWidget {
+  @override
+  _ThrowingWidgetState createState() => _ThrowingWidgetState();
+}
+
+class _ThrowingWidgetState extends State<ThrowingWidget> {
+  @override
+  void initState() {
+    super.initState();
+    topLevelFunction();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Container();
+  }
+}
+
+@noInline
+void topLevelFunction() {
+  secondLevelFunction();
+}
+
+@noInline
+void secondLevelFunction() {
+  thirdLevelFunction();
+}
+
+@noInline
+void thirdLevelFunction() {
+  throw Exception('Test error message');
+}

packages/flutter/lib/src/foundation/assertions.dart

@@ -944,22 +944,32 @@ class FlutterError extends Error with DiagnosticableTreeMixin implements Asserti
   static void dumpErrorToConsole(FlutterErrorDetails details, { bool forceReport = false }) {
     assert(details != null);
     assert(details.exception != null);
-    bool reportError = details.silent != true; // could be null
+    bool isInDebugMode = false;
     assert(() {
       // In checked mode, we ignore the "silent" flag.
-      reportError = true;
+      isInDebugMode = true;
       return true;
     }());
+    final bool reportError = isInDebugMode || details.silent != true; // could be null
     if (!reportError && !forceReport)
       return;
     if (_errorCount == 0 || forceReport) {
-      debugPrint(
-        TextTreeRenderer(
-          wrapWidth: wrapWidth,
-          wrapWidthProperties: wrapWidth,
-          maxDescendentsTruncatableNode: 5,
-        ).render(details.toDiagnosticsNode(style: DiagnosticsTreeStyle.error)).trimRight(),
-      );
+      // Diagnostics is only available in debug mode. In profile and release modes fallback to plain print.
+      if (isInDebugMode) {
+        debugPrint(
+          TextTreeRenderer(
+            wrapWidth: wrapWidth,
+            wrapWidthProperties: wrapWidth,
+            maxDescendentsTruncatableNode: 5,
+          ).render(details.toDiagnosticsNode(style: DiagnosticsTreeStyle.error)).trimRight(),
+        );
+      } else {
+        debugPrintStack(
+          stackTrace: details.stack,
+          label: details.exception.toString(),
+          maxFrames: 100,
+        );
+      }
     } else {
       debugPrint('Another exception was thrown: ${details.summary}');
     }