guess_assess() can’t return false for second return value

[Mr0grog]

Apologies if I am missing something obvious here, but I was doing a bunch of testing with chardetng and noticed that the second return value from EncodingDetector.guess_assess() (the boolean indicating whether the guess was any good) never seems to be false. Looking at the source, it actually seems like it’s not possible:

• The max variable that tracks the best score starts at 0:

  chardetng/src/lib.rs

  Line 3003 in 143dadd

  let mut max = 0i64;

• It only ever gets updated with scores that are greater than the current value (so: always >= 0):

  chardetng/src/lib.rs

  Lines 3043 to 3048 in 143dadd

  	for (i, candidate) in self.candidates.iter().enumerate().skip(Self::FIRST_NORMAL) {
  	if let Some(score) = candidate.score(i, tld_type, expectation_is_valid) {
  	if score > max {
  	max = score;
  	encoding = candidate.encoding();
  	}

• The final boolean is just whether max is >= 0, which it always is, per the above points:

  chardetng/src/lib.rs

  Line 3062 in 143dadd

  (encoding, max >= 0)

  I think this should probably be max > 0, which would mean you’d get a false if there were no better guesses than the default encoding for the TLD (or if the only good guess is ISO-8859-8? That’s a bit odd…). I’m not familiar enough with the internals here to know for sure what the right thing would be.

It looks like max used to start with a negative value, so maybe that’s how this issue came to be? (That said, it changed in 0d26e7e, which was before guess_assess() existed. 🤷)

chardetng/src/lib.rs

Line 1734 in f15d0f8

let mut max = i64::min_value() + 1;

Again, apologies if I’ve missed something obvious here and this isn’t a real issue — I don’t have a lot of experience with Rust. But this does seem to match up with what I’ve seen so far throwing lots of different data at chardetng and never seeing a false result.