Index error with SQL language plugin

plinnegan · July 3, 2024, 9:34am

I’ve been troubleshooting an issue where inserting a right parenthesis in the editor causes an error:

ReferenceError: _i is not defined

Which tracing it was coming from here in the @lezer/lr package:

github.com

lezer-parser/lr/blob/main/src/stack.ts#L288


      
          
          let nextStates = this.p.parser.nextStates(this.state)
          if (nextStates.length > Recover.MaxNext << 1 || this.stack.length >= Recover.DampenInsertStackDepth) {
            let best = []
            for (let i = 0, s; i < nextStates.length; i += 2) {
              if ((s = nextStates[i + 1]) != this.state && this.p.parser.hasAction(s, next))
                best.push(nextStates[i], s)
            }
            if (this.stack.length < Recover.DampenInsertStackDepth)
              for (let i = 0; best.length < Recover.MaxNext << 1 && i < nextStates.length; i += 2) {
                let s = nextStates[i + 1]
                if (!best.some((v, i) => (i & 1) && v == s)) best.push(nextStates[i], s)
              }
            nextStates = best
          }
          let result: Stack[] = []
          for (let i = 0; i < nextStates.length && result.length < Recover.MaxNext; i += 2) {
            let s = nextStates[i + 1]
            if (s == this.state) continue
            let stack = this.split()
            stack.pushState(s, this.pos)

Seriously scratching my head over this, as when I created the same setup with the same package versions in code sandbox there was no error.

Just because I had run out of ideas, I tried changing the variable in the for loop from i to j and this resolved the issue. Because I can’t reproduce I’m not raising it as a bug on Github, but would be interested to hear if people have any thoughts on why this might be happening?

I’ve generated a patch for the change in our project, so it’s not a blocking issue for us, but of course I would ideally like to not have to rely on a patch.

marijn · July 3, 2024, 9:48am

Seeing how the variable is not called _i in the source (or in the bundled code in the package’s dist dir), I suspect some tool you’re running on this on your side might be transforming the code in a broken way.

plinnegan · July 3, 2024, 10:19am

Sounds like a likely culprit. Yes looking at the minified code, it seems to have been incorrectly minified, thanks for the guidance.

if (t.length > 8 || this.stack.length >= 120) {
    for (var n, r = [], o = 0; o < t.length; o += 2)
        (n = t[o + 1]) != this.state && this.p.parser.hasAction(n, e) && r.push(t[o], n);
    if (this.stack.length < 120)
        for (var a = function() {
            var e = t[_i + 1];
            r.some((function(t, n) {
                return 1 & n && t == e
            }
            )) || r.push(t[_i], e)
        }, i = 0; r.length < 8 && i < t.length; i += 2)
            a();
    t = r
}