Incorrect missing operator warning if []= is defined but not []

[DartBot]

This issue was originally filed by jbrose...@google.com

---

Consider the following code:

main() {
  Fred fred = new Fred();
  int x = 7, y = 23;
  String result = (fred[x] = y);
  print("Got result $result");
}

class Fred {
  String operator []=(int x, int y) {
    print("Inside []= operator code, x = $x, y = $y");
    return "${x} + ${y} = ${x + y}";
  }
}

When I run this on dartboard, it shows a warning: "Fred has no method named 'operator[]'".
It then appears to successfully execute the code and invoke the operator code.

So it appears to be warning incorrectly, but otherwise ignoring the issue. If I add the operator [] to Fred, the warning goes away.

Jason

[DartBot]

This comment was originally written by jbrose...@google.com

---

I should note, that running this code on the stand-alone vm does not produce this warning.

[DartBot]

This comment was originally written by drfibonacci@google.com

---

Removed Area-Language label.
Added Area-Dartboard, Triaged labels.

[dgrove]

At some point, we would like to create a next-generation Dartboard. In the meantime, dartboard has been deprecated.

---

Added WontFix label.