Inline comment after func params is printed inside the params

Original

I’ve migrated a large codebase which used this function definition style:

function func(a, b)  // `a` is the first arg
{
 return 'done'
}

Reprinted

prettier reprinted all comments following function params like this:

function func(
  a,
  b // `a` is the first arg
) {
  return "done";
}

This is extra confusing as the comment is on the same line as a parameter it does not refer to. We have many of these cases as you might imagine.

Proposal

The comment must be moved since an inline comment can’t appear between the closing paren and opening curly: ) {. Since the original comment was not inside the parentheses, IMHO, it should not be moved inside when reprinted.

I would think most humans would rewrite the original function with the comment on the line above the function:

// `a` is the first arg
function func(a, b) {
  return "done";
}

---

Would love to hear feedback on this.

https://prettier.io/playground/#{“content”%3A"function func(a%2C b) %2F%2F `a` is the first arg\n{\n return ‘done’\n}“%2C"options”%3A{“printWidth”%3A80%2C"tabWidth"%3A2%2C"singleQuote"%3Afalse%2C"trailingComma"%3A"es5"%2C"bracketSpacing"%3Atrue%2C"jsxBracketSameLine"%3Afalse%2C"parser"%3A"babylon"%2C"semi"%3Atrue%2C"useTabs"%3Afalse%2C"doc"%3Afalse%2C"ast"%3Afalse}}

[levithomason]

Hm, thinking this through. I’m not sure what the impact might be to code that must appear directly above a function like decorators, docblocks, etc.

A less desirable alternative might be to print the inline comment on the first line of the func body. Will leave it at that for now.

[levithomason]

Agreed, closing for the sake of progress.