Improve S2189 (no-infinite-loop) by reporting only on local vars

[saberduck]

We use ESLint's no-unmodified-loop-condition for this rule. It seems to be a bit noisy, because we are not able to detect cross-procedural modifications of the loop variables. We could significantly lower the number of FPs by not reporting on variables which are not defined locally in the function.

Another minor improvement - we should only report once per symbol, maybe with secondary location for other occurrences of the symbol within the loop condition

[saberduck]

There are multiple FP patterns for the no-unmodified-loop rule we are using, I think we should consider rewriting the rule completely. Some of the FP patterns are documented below

// control flow statements like break or return
let attempts = 3;
while(expected) {
  if (--attempts < 0) {
    break;
  }
}

// variable is part of more complex condition
function foo(cursor, skipWhitespace) {
    var token = this.getToken(cursor),
        next = token,
        doc = this.editor.document;
    do {
        if (next.end > cursor.ch) {
            cursor.ch = next.end;
        } else if (next.end < doc.getLine(cursor.line).length) {
            cursor.ch = next.end + 1;
        } else if (doc.getLine(cursor.line + 1)) {
            cursor.ch = 0;
            cursor.line++;
        } else {
            next = null;
            break;
        }
        next = this.getToken(cursor);
    } while (skipWhitespace && !/\S/.test(next.string)); // FP on skipWhitespace
}

When the rule is improved we can consider enabling it for TypeScript.

[ericmorand-sonarsource]

Here is an additional false positive that is most probably triggered by this issue:

https://community.sonarsource.com/t/rule-javascript-s2189-false-positive-in-loop-exit-condition/109778