Issue 88543: TextField labelText doesn't get hintTextStyle when labelTextStyle is non-null Fixed (flutter#89386)

labelText now gets hintTextStyle when no labelStyle, per the docs

Author: varunkamanibosc

packages/flutter/lib/src/material/input_decorator.dart

@@ -2231,12 +2231,14 @@ class _InputDecoratorState extends State<InputDecorator> with TickerProviderStat
       isHovering: isHovering,
     );
 
+    final TextStyle? inlineLabelStyle = decoration!.label != null ? decoration!.labelStyle : decoration!.hintStyle;
+
     // Temporary opt-in fix for https://github.com/flutter/flutter/issues/54028
     // Setting TextStyle.height to 1 ensures that the label's height will equal
     // its font size.
-    final TextStyle inlineLabelStyle = themeData.fixTextFieldOutlineLabel
-      ? inlineStyle.merge(decoration!.labelStyle).copyWith(height: 1)
-      : inlineStyle.merge(decoration!.labelStyle);
+    final TextStyle effectiveInlineLabelStyle = themeData.fixTextFieldOutlineLabel
+      ? inlineStyle.merge(inlineLabelStyle).copyWith(height: 1)
+      : inlineStyle.merge(inlineLabelStyle);
     final Widget? label = decoration!.labelText == null && decoration!.label == null ? null : _Shaker(
       animation: _shakingLabelController.view,
       child: AnimatedOpacity(
@@ -2248,7 +2250,7 @@ class _InputDecoratorState extends State<InputDecorator> with TickerProviderStat
           curve: _kTransitionCurve,
           style: widget._labelShouldWithdraw
             ? _getFloatingLabelStyle(themeData)
-            : inlineLabelStyle,
+            : effectiveInlineLabelStyle,
           child: decoration!.label ?? Text(
             decoration!.labelText!,
             overflow: TextOverflow.ellipsis,
@@ -2371,7 +2373,7 @@ class _InputDecoratorState extends State<InputDecorator> with TickerProviderStat
       contentPadding = decorationContentPadding ?? EdgeInsets.zero;
     } else if (!border.isOutline) {
       // 4.0: the vertical gap between the inline elements and the floating label.
-      floatingLabelHeight = (4.0 + 0.75 * inlineLabelStyle.fontSize!) * MediaQuery.textScaleFactorOf(context);
+      floatingLabelHeight = (4.0 + 0.75 * effectiveInlineLabelStyle.fontSize!) * MediaQuery.textScaleFactorOf(context);
       if (decoration!.filled == true) { // filled == null same as filled == false
         contentPadding = decorationContentPadding ?? (decorationIsDense
           ? const EdgeInsets.fromLTRB(12.0, 8.0, 12.0, 8.0)

packages/flutter/test/material/input_decorator_test.dart

@@ -3422,7 +3422,7 @@ void main() {
     expect(tester.widget<Text>(find.text('suffix')).style!.color, suffixStyle.color);
     expect(tester.widget<Text>(find.text('helper')).style!.color, helperStyle.color);
     expect(tester.widget<Text>(find.text('counter')).style!.color, counterStyle.color);
-    expect(getLabelStyle(tester).color, labelStyle.color);
+    expect(getLabelStyle(tester).color, hintStyle.color);
   });
 
   testWidgets('InputDecorationTheme style overrides (focused)', (WidgetTester tester) async {
@@ -5244,4 +5244,66 @@ void main() {
     // Verify that the styles were passed along
     expect(getLabelStyle(tester).color, labelStyle.color);
   });
+
+  testWidgets('hintStyle is used for labelText when labelText is on top of the input field and labelStyle is used for labelText when labelText moves above widget', (WidgetTester tester) async {
+    const TextStyle style16 = TextStyle(fontFamily: 'Ahem', fontSize: 16.0);
+    final TextStyle labelStyle = style16.merge(const TextStyle(color: Colors.purple));
+    final TextStyle hintStyle = style16.merge(const TextStyle(color: Colors.red));
+
+    await tester.pumpWidget(
+      buildInputDecorator(
+        isEmpty: true,
+        isFocused: false, // Label appears inline, on top of the input field.
+        decoration: InputDecoration(
+          labelText: 'label',
+          labelStyle: labelStyle,
+          hintStyle: hintStyle,
+        ),
+      ),
+    );
+
+    // Overall height for this InputDecorator is 56dps:
+    //   12 - top padding
+    //   12 - floating label (ahem font size 16dps * 0.75 = 12)
+    //    4 - floating label / input text gap
+    //   16 - input text (ahem font size 16dps)
+    //   12 - bottom padding
+    expect(tester.getSize(find.byType(InputDecorator)), const Size(800.0, 56.0));
+    expect(tester.getTopLeft(find.text('label')).dy, 20.0);
+    expect(tester.getBottomLeft(find.text('label')).dy, 36.0);
+    expect(getBorderBottom(tester), 56.0);
+    expect(getBorderWeight(tester), 1.0);
+
+    // Verify that the hintStyle was used
+    expect(getLabelStyle(tester).color, hintStyle.color);
+
+    await tester.pumpWidget(
+      buildInputDecorator(
+        isEmpty: true,
+        isFocused: true, // Label moves above (i.e., vertically adjacent to) the input field
+        decoration: InputDecoration(
+          labelText: 'label',
+          labelStyle: labelStyle,
+          hintStyle: hintStyle,
+        ),
+      ),
+    );
+
+    await tester.pumpAndSettle();
+
+    // Overall height for this InputDecorator is 56dps:
+    //   12 - top padding
+    //   12 - floating label (ahem font size 16dps * 0.75 = 12)
+    //    4 - floating label / input text gap
+    //   16 - input text (ahem font size 16dps)
+    //   12 - bottom padding
+    expect(tester.getSize(find.byType(InputDecorator)), const Size(800.0, 56.0));
+    expect(tester.getTopLeft(find.text('label')).dy, 12.0);
+    expect(tester.getBottomLeft(find.text('label')).dy, 24.0);
+    expect(getBorderBottom(tester), 56.0);
+    expect(getBorderWeight(tester), 2.0);
+
+    // Verify that the labelStyle was used
+    expect(getLabelStyle(tester).color, labelStyle.color);
+  });
 }