invariant_booleans false positive when using assignment operator (like +=)

[ghost]

@jfphilbin commented on Dec 17, 2018, 9:54 AM UTC:

In Dart SDK Version2.2.0-dev.1.1 on Windows 10, the following code:

void main() {
  foo('****', 0, 5);
}

int foo(int start, int end, [int x = 0]) {
  var s = 0, index = start;
  if ((index += 2) < end) {
    if ((index += 2) < end) {  // Info here
      if (x == null) s = 1;
    }
 }
 return s;
}

Generates the following Analyzer Info:

info: Conditions should not unconditionally evaluate to `true` or to `false`. verify: (index += 2) < end. 
    (invariant_booleans at [core] bin\bug.dart:15)

Which I think is incorrect.

This issue was moved by stereotype441 from dart-lang/sdk#35429.

[stereotype441]

@pq FYI

[srawlins]

Another invariant_booleans false positive. This time the issue is +=.

[srawlins]

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