From 7d539043bae8a7f342cd4ba6694df58a4d31f925 Mon Sep 17 00:00:00 2001
From: LongCatIsLooong <31859944+LongCatIsLooong@users.noreply.github.com>
Date: Mon, 2 Nov 2020 13:43:02 -0800
Subject: [PATCH] dont mess with user supplied list (#69594)

---
 .../flutter/lib/src/cupertino/text_field.dart    |  8 ++++----
 .../flutter/lib/src/material/text_field.dart     |  7 ++++---
 .../flutter/test/cupertino/text_field_test.dart  | 12 ++++++++++++
 .../flutter/test/material/text_field_test.dart   | 16 ++++++++++++++++
 4 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/packages/flutter/lib/src/cupertino/text_field.dart b/packages/flutter/lib/src/cupertino/text_field.dart
index f69a235ccf4..3473130fce5 100644
--- a/packages/flutter/lib/src/cupertino/text_field.dart
+++ b/packages/flutter/lib/src/cupertino/text_field.dart
@@ -878,13 +878,13 @@ class _CupertinoTextFieldState extends State<CupertinoTextField> with Restoratio
     super.build(context); // See AutomaticKeepAliveClientMixin.
     assert(debugCheckHasDirectionality(context));
     final TextEditingController controller = _effectiveController;
-    final List<TextInputFormatter> formatters = widget.inputFormatters ?? <TextInputFormatter>[];
     final TextSelectionControls textSelectionControls = widget.selectionControls ?? cupertinoTextSelectionControls;
     final bool enabled = widget.enabled ?? true;
     final Offset cursorOffset = Offset(_iOSHorizontalCursorOffsetPixels / MediaQuery.of(context).devicePixelRatio, 0);
-    if (widget.maxLength != null && widget.maxLengthEnforced) {
-      formatters.add(LengthLimitingTextInputFormatter(widget.maxLength));
-    }
+    final List<TextInputFormatter> formatters = <TextInputFormatter>[
+      ...?widget.inputFormatters,
+      if (widget.maxLength != null && widget.maxLengthEnforced) LengthLimitingTextInputFormatter(widget.maxLength)
+    ];
     final CupertinoThemeData themeData = CupertinoTheme.of(context);
 
     final TextStyle? resolvedStyle = widget.style?.copyWith(
diff --git a/packages/flutter/lib/src/material/text_field.dart b/packages/flutter/lib/src/material/text_field.dart
index 729634bff21..3b4a00aaedd 100644
--- a/packages/flutter/lib/src/material/text_field.dart
+++ b/packages/flutter/lib/src/material/text_field.dart
@@ -1261,9 +1261,10 @@ class _TextFieldState extends State<TextField> with RestorationMixin implements
     final Brightness keyboardAppearance = widget.keyboardAppearance ?? theme.primaryColorBrightness;
     final TextEditingController controller = _effectiveController;
     final FocusNode focusNode = _effectiveFocusNode;
-    final List<TextInputFormatter> formatters = widget.inputFormatters ?? <TextInputFormatter>[];
-    if (widget.maxLength != null && widget.maxLengthEnforced)
-      formatters.add(LengthLimitingTextInputFormatter(widget.maxLength));
+    final List<TextInputFormatter> formatters = <TextInputFormatter>[
+      ...?widget.inputFormatters,
+      if (widget.maxLength != null && widget.maxLengthEnforced) LengthLimitingTextInputFormatter(widget.maxLength)
+    ];
 
     TextSelectionControls? textSelectionControls = widget.selectionControls;
     final bool paintCursorAboveText;
diff --git a/packages/flutter/test/cupertino/text_field_test.dart b/packages/flutter/test/cupertino/text_field_test.dart
index 452408a2c33..6564044a250 100644
--- a/packages/flutter/test/cupertino/text_field_test.dart
+++ b/packages/flutter/test/cupertino/text_field_test.dart
@@ -4289,4 +4289,16 @@ void main() {
     final EditableText widget = tester.widget(find.byType(EditableText));
     expect(widget.selectionControls, equals(selectionControl));
   });
+
+  testWidgets('Do not add LengthLimiting formatter to the user supplied list', (WidgetTester tester) async {
+    final List<TextInputFormatter> formatters = <TextInputFormatter>[];
+
+    await tester.pumpWidget(
+      CupertinoApp(
+        home: CupertinoTextField(maxLength: 5, inputFormatters: formatters),
+      )
+    );
+
+    expect(formatters.isEmpty, isTrue);
+  });
 }
diff --git a/packages/flutter/test/material/text_field_test.dart b/packages/flutter/test/material/text_field_test.dart
index f7f50a41b34..fce098fb330 100644
--- a/packages/flutter/test/material/text_field_test.dart
+++ b/packages/flutter/test/material/text_field_test.dart
@@ -3344,6 +3344,22 @@ void main() {
     expect(textController.text, '145623');
   });
 
+  testWidgets('Do not add LengthLimiting formatter to the user supplied list', (WidgetTester tester) async {
+    final List<TextInputFormatter> formatters = <TextInputFormatter>[];
+
+    await tester.pumpWidget(
+      overlay(
+        child: TextField(
+          decoration: null,
+          maxLength: 5,
+          inputFormatters: formatters,
+        ),
+      ),
+    );
+
+    expect(formatters.isEmpty, isTrue);
+  });
+
   testWidgets('Text field scrolls the caret into view', (WidgetTester tester) async {
     final TextEditingController controller = TextEditingController();