Parse error in `for` statement when identifier `of` is divided

[quiqueg]

Similar to https://github.com/guybedford/es-module-lexer/issues/173 and https://github.com/guybedford/es-module-lexer/issues/177.

Steps to reproduce

1. for statement which contains:
   • of as an identifier on the left side of a binary expression, whose operator is /

Minimal source code

for (i = of / 2;;) break

for (; of / 2;) break

for (;; of / 2) break

Also affects for..of and for..in statements

However, these are both pathological examples: while they are valid JavaScript, of / 2 would have to produce an iterable for these to execute without error.

for (i of of / 2) break

for (i in of / 2) break

Full repro

import { init, parse } from 'es-module-lexer';
(async () => {
  await init;
  parse('for (i = of / 2;;) {}');
})();

Error: Parse error @:1:22
    at parse (file:///app/node_modules/.pnpm/[email protected]/node_modules/es-module-lexer/dist/lexer.js:2:682)
    at file:///app/index.mjs:4:3 {
  idx: 21
}

Affected versions

Reproducible in versions 1.5.1 through 1.7.0.

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Like https://github.com/guybedford/es-module-lexer/issues/177, we unfortunately have this code in our minified Vite output and so our CI/CD broke. I somehow managed to find it in our 8MB minified JS file 🫠

[guybedford]

Thanks for clearing the clear reproduction on this one. This edge case gets to the heart of the projects assumptions, and fixing it is a heuristic exercise unfortunately. The question is then just how well we can patch these edge cases.

I've put together a fix for this in https://github.com/guybedford/es-module-lexer/pull/195, but before releasing that I'd really value some more eyes on it to determine if there are more edge cases I'm missing here.