[linter] Super initialization with optional parameter leads to unused_element

[srujzs]

Dart version: Dart SDK version: 3.5.0-edge.eea3bb5c4fbd09b5f1ba662a5ce19f032b6dba15 (main) (Wed May 8 08:13:44 2024 -0700) on "macos_arm64"

Consider the following Dart code:

class _A {
  final String? f;

  _A([this.f]);
}

class _B extends _A {
  _B();
}

class _C extends _A {
  _C(super.f);
}

void main() {
  _B();
  _C('');
}

The above results in an unused_element diagnostic around this.f, even though _C uses it to provide a value for f.

If we replace _C with:

class _C extends _A {
  _C(String f2) : super(f2);
}

The lint goes away. Should the lint not trigger in the super initialization syntax, or is there some better syntax I should be using?

[bwilkerson]

The warning should not be produced in this case.