Bug with whitespace

[acrazing]

Bug Report

• TSLint version: 4.5.1
• TypeScript version: 2.2.1
• Running TSLint via: CLI

TypeScript code being linted

// code snippet
for (let i = 0; i < 1;) {
  console.log(i++)
}

with tslint.json configuration:

{
  "rules": {
    "whitespace": [
      true,
      "check-branch",
      "check-decl",
      "check-operator",
      "check-module",
      "check-separator",
      "check-type"
    ]
  }
}

Actual behavior

Emit error:

src/__test__/tslint.ts[12, 23]: missing whitespace

Expected behavior

No error.

[MarkPieszak]

This bug is actually creating crazy issues in VSCode where you have to basically disable the whitepsace check, otherwise it throws random errors for lines all in the incorrect locations etc.

[sbj42]

I haven't seen this rule throw "random errors", but a related case I have seen is when using for (;;) to make an infinite loop (without triggering strict-boolean-expressions). TSLint warns about this code:

for (;;) {
    const c = peek();
    if (typeof c === 'undefined') {
        break;
    }
    handle(c);
}

And it is only appeased by:

for (; ; ) {

Which seems unnecessary to me. My recommendation is to make an exception for the "check-separator" case when the following element is empty/absent. That should cover both cases. It would also allow something like const [a,, b] = ignoreMiddleReturn() - I'm not sure if that's problematic.

[ajafff]

Fixed by #3132