supertype_expands_to_type_parameter
A type alias that expands to a type parameter can't be implemented.
A type alias that expands to a type parameter can't be mixed in.
A type alias that expands to a type parameter can't be used as a superclass constraint.
A type alias that expands to a type parameter can't be used as a superclass.
Description
#The analyzer produces this diagnostic when a type alias that expands to a
type parameter is used in an extends, implements, with, or on
clause.
Example
#The following code produces this diagnostic because the type alias T,
which expands to the type parameter S, is used in the extends clause of
the class C:
dart
typedef T<S> = S;
class C extends T<Object> {}Common fixes
#Use the value of the type argument directly:
dart
typedef T<S> = S;
class C extends Object {}除非另有说明，文档之所提及适用于 Dart 3.7.3 版本，本页面最后更新时间: 2025-05-08。 查看文档源码 或者 报告页面问题。