invariant_booleans false positive

[pq]

From @DanTup on August 17, 2018 17:54

This may be a dupe of #28262, #29431 or #28967 but it looks different to me so I thought it worth raising.

var hasAnError = false;
void danny() {
  if (hasAnError) {
    return;
  }
  setError();
  if (hasAnError) { // Conditions should not unconditionally evaluate to `true` or to `false`.
    return;
  }
  print('Running');
}

void setError() {
  hasAnError = true;
}

I wouldn't expect it to look through all called code to see if the variable is set, but possibly it's a bit too keen to report here.

Copied from original issue: #34173

[pq]

From @DanTup on August 19, 2018 11:53

This one is even simpler:

void test(int a, int b) {
  if (a < b) {
    print('a < b');
  } else if (b < a) {
    print('b < a');
  }
}

The lint fires for the else if condition, but it's not unconditionally true or false? Strangely, if I make it b <= a (which I think would make it always true, since it's effectively an else) the lint disappears.

[pq]

From @zoechi on August 19, 2018 17:45

Also similar #57535, #57601

[pq]

FWIW: this may be a dup; we should verify.

[jakemac53]

@grouma hit this today also (similar to the first case here), it probably shouldn't try to lint about anything other than local variables? Anything else seems like it would be to difficult to properly track down.

[srawlins]

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