看起来你现在需要在你的覆盖中指定sizeWithOverflow：https://api.flutter.dev/flutter/material/SliderComponentShape/paint.html我不熟悉这个字段，但在Github代码中似乎有对该参数的描述：
https://github.com/flutter/flutter/blob/2ae34518b8/packages/flutter/lib/src/material/slider_theme.dart#L1006
因此，您需要将上述内容更改为：

@override
void paint(
    PaintingContext context,
    Offset center, {
    Animation<double> activationAnimation,
    Animation<double> enableAnimation,
    bool isDiscrete,
    TextPainter labelPainter,
    RenderBox parentBox,
    Size sizeWithOverflow, /*The missing link*/
    double textScaleFactor, /*And the missing link I missed*/
    SliderThemeData sliderTheme,
    TextDirection textDirection,
    double value,
  }) {

希望能帮上忙。
P.S.我建议将来使用文本比较工具来更容易地解决这类问题。我喜欢使用BeyondCompare，但这就是我。

如果你的课碰巧是这样的，

class YourClass extends SliderTrackShape
with BaseSliderTrackShape

你遇到这个错误，你最喜欢的一个参数是

Offset? secondaryOffset

整个结构应该是这样的

@override
  void paint(
    PaintingContext context,
    Offset offset, {
    @required RenderBox? parentBox,
    @required SliderThemeData? sliderTheme,
    @required Animation<double>? enableAnimation,
    @required TextDirection? textDirection,
    @required Offset? thumbCenter,
    bool isDiscrete = false,
    bool isEnabled = false,
    double additionalActiveTrackHeight = 2,
    Offset? secondaryOffset,
  })