fixed cupertinoTextField placeholder textAlign (#33739)

packages/flutter/lib/src/cupertino/text_field.dart

@@ -744,13 +744,17 @@ class _CupertinoTextFieldState extends State<CupertinoTextField> with AutomaticK
         // if needed.
         if (widget.placeholder != null && text.text.isEmpty) {
           stackChildren.add(
-            Padding(
-              padding: widget.padding,
-              child: Text(
-                widget.placeholder,
-                maxLines: 1,
-                overflow: TextOverflow.ellipsis,
-                style: placeholderStyle
+            SizedBox(
+              width: double.infinity,
+              child: Padding(
+                padding: widget.padding,
+                child: Text(
+                  widget.placeholder,
+                  maxLines: widget.maxLines,
+                  overflow: TextOverflow.ellipsis,
+                  style: placeholderStyle,
+                  textAlign: widget.textAlign,
+                ),
               ),
             ),
           );

packages/flutter/test/cupertino/text_field_test.dart

@@ -544,6 +544,31 @@ void main() {
     },
   );
 
+  testWidgets(
+    'placeholder respects textAlign',
+    (WidgetTester tester) async {
+      await tester.pumpWidget(
+        const CupertinoApp(
+          home: Center(
+            child: CupertinoTextField(
+              placeholder: 'placeholder',
+              textAlign: TextAlign.right,
+            ),
+          ),
+        ),
+      );
+
+      final Text placeholder = tester.widget(find.text('placeholder'));
+      expect(placeholder.textAlign, TextAlign.right);
+
+      await tester.enterText(find.byType(CupertinoTextField), 'input');
+      await tester.pump();
+
+      final EditableText inputText = tester.widget(find.text('input'));
+      expect(placeholder.textAlign, inputText.textAlign);
+    },
+  );
+
   testWidgets(
     'placeholders are lightly colored and disappears once typing starts',
     (WidgetTester tester) async {