Enhancing Flexibility in Method Overrides

Dart's strict method signature matching for overrides limits subclasses from using meaningful parameter names. This impacts methods clarity and usability, leading to unnecessary boilerplate.

```dart
// Bass class
class Pair {
final T first;
final U second;

Pair(this.first, this.second);

Pair copyWith({T? first, U? second}) => Pair(
first ?? this.first,
second ?? this.second,
);
}

//Subclass
class Range extends Pair {
Range({T? lower, T? upper}) : super(lower, upper);

T? get lower => first;
T? get upper => second;

// Overriding copyWith without signature mismatch, but losing clarity.
@override
Range copyWith({T? first, T? second}) => Range(
lower: first ?? this.lower,
upper: second ?? this.upper,
);

// A separate copyWithRange method that is redundant and inefficient
Range copyWithRange({T? lower, T? upper}) => Range(
lower: lower ?? this.lower,
upper: upper ?? this.upper,
);

// Ideal, but causes signature mismatch error
@override
Range copyWith({T? lower, T? upper}) => Range(
lower: lower ?? this.lower,
upper: upper ?? this.upper,
);
}
```

In this example, the subclass `Range` ideally wants to use parameters like `lower` and `upper` to represent the bounds of the range, but is forced to stick with `first` and `second` to avoid signature mismatches. Introducing another method like `copyWithRange` becomes redundant and inefficient.

### Solution Proposal:
Dart should allow parameter renaming in method overrides, maintaining type compatibility with the base class. This would enhance clarity without breaking contracts.

**Possible Syntax:**
```dart
Range copyWith({
T? lower as first,
T? upper as second
}) => Range(
lower: lower ?? this.lower,
upper: upper ?? this.upper,
);
```
In this solution, the `lower` and `upper` parameters are mapped to the base class's `first` and `second`, allowing more meaningful parameter names in the subclass without breaking the base class contract.

Start with the Pair and Range example in the issue and review Dart's existing method-override rules for named parameters. Compare the proposed `lower as first` and `upper as second` syntax against type compatibility and base-class callers; done means the language-design tradeoffs and required behavior are documented or decided.

Written by the indexing model from the issue text.