avoid-unused-generics
Warns when a function or method declares unused generic types.
Unused generics are usually a sign of a bug or can appear after code refactoring.
⚙️ Config
Set ignore-overridden (default is false) to ignore methods that have the @override annotation (example).
analysis_options.yaml
dart_code_metrics:
rules:
- avoid-unused-generics:
ignore-overridden: false
Example
❌ Bad:
class SomeClass {
// LINT: This generic type is not used. Try removing it or referencing it in code.
String unused<T extends num>() {
// ...
}
// LINT: This generic type is not used. Try removing it or referencing it in code.
String multiple<T, U>(U param) {
// ...
}
}
// LINT: This generic type is not used. Try removing it or referencing it in code.
void function<T>() {
return;
}
✅ Good:
class SomeClass {
String used<T extends num>() { // Correct, 'T' is used
return (value as T).toString();
}
T multiple<T, U>(U param) { // Correct, both generics are used
// ...
}
}
void function() {
return;
}
Example with "ignore-overridden"
Config
analysis_options.yaml
dart_code_metrics:
rules:
- avoid-unused-generics:
ignore-overridden: true
✅ Good:
abstract class Abstract {
void fn<T>();
}
class Child extends Abstract {
void fn<T>() { // Correct, overridden declaration
return;
}
}