Warning emitted for rule that contains a seq with a single argument

[sogaiu]

Since commit tree-sitter/tree-sitter@252e2a4 of the tree-sitter cli, the generate subcommand gives a warning for our grammar (at least at f4236d4):

Warning: rule char_lit is just a `seq` or `choice` rule with a single element. This is unnecessary.

It takes a bit of digging, but the culprit is here [1]:

const OCTAL_CHAR =
      seq("o",
          choice(seq(DIGIT, DIGIT, DIGIT),
                 seq(DIGIT, DIGIT),
                 seq(DIGIT)));

The last seq is seq(DIGIT), which does indeed have a single argument.

I don't know if this is a serious issue, but perhaps it makes sense to remove the seq there.

---

[1] Thanks to clason and amaanq for getting to the bottom of this. Some more background can be found here.

[sogaiu]

As a bit of a follow-up, I came across this text:

(char_lit) being marked as having an unnecessary seq is part of a token construct, and so the warning isn't necessary in this case.

here.

Not sure if that means the grammar is fine in its current state.

The seq in question does seem spurious to me though.

[sogaiu]

Apparently, the change to tree-sitter was reverted.

Might still be worth making the change at some point, but it doesn't seem like an urgent matter.

[sogaiu]

For reference, this change has been tested as part of investigations and explorations related to this issue.