Incorrect prefer_is_empty warning

[spkersten]

Consider:

class Foo {
  const Foo(List<int> numbers)
      : assert(numbers.length > 0),
        assert(numbers.isNotEmpty);
}

The first assert results in a warning say:

info: Use isNotEmpty instead of length (prefer_is_empty at [...] ...)

But following that suggestion (the second assert) is an error:

error: Invalid constant value. (invalid_constant at [...] ...)

Dart 2.7.0

[srawlins]

Thanks for opening!

[bruno-garcia]

This came up in #57805
I believe it was fixed through dart-archive/linter#2122 and landed in master June 2nd and is on the release notes of 0.1.117

~I'm on Dart version 2.9.0 (build 2.9.0-21.10.beta) and still affected by this issue. ~

Not sure how the linter release gets through into Dart to check versions

Actually my VS Code integration wasn't on 2.9.0 but 2.8.0 instead which didn't have the fix.

I can confirm it's fixed with Dart 2.9.0 and this issue can be closed.