Bogus invariant_booleans analyzer warning

[apwilson]

This code has an analyzer warning that's bogus imo.

enum _Foo { x, y, z }

///
class Baz {
  final double _a;
  final double _b;

  ///
  Baz(this._a, this._b);
  bool get _isHorizontal => _a == _b;

  ///
  bool doSomething(_Foo foo) {
    switch (foo) {
      case _Foo.x:
        if (_isHorizontal) {
          return false;
        }
        break;
      case _Foo.y:
        if (_isHorizontal) {
          return false;
        }
        break;
      case _Foo.z:
      default:
        break;
    }
    return true;
  }
}

[srawlins]

I can recreate this. I'll even show where the error is:

$ dart bin/linter.dart --rules invariant_booleans 29407.dart 
/Users/srawlins/code/dart-linter/29407.dart 21:13 [lint] Conditions should not unconditionally evaluate to `true` or to `false`. verify: _isHorizontal.
        if (_isHorizontal) {
            ^^^^^^^^^^^^^

1 file analyzed, 1 issue found, in 1427 ms.

No idea why the lint rule would complain about the second if (_isHorizontal) but not the first...

[jamesderlin]

This looks rather similar to #57601 (multiple switch cases with a repeated condition).

[srawlins]

We've deprecated invariant_booleans and will not be fixing correctness bugs going forward.