Removes comma in first object literal of a function with line comment in arguments

[AngusFu]

Weird bug. The following screenshot describes better than words.

BTW, I got the function from Vue dist file vue.esm.js at line 4384.

function createComponentInstanceForVnode (
  vnode, // we know it's MountedComponentVNode but flow doesn't
  parent // activeInstance in lifecycle state
) {
  var options = {
    _isComponent: true,
    _parentVnode: vnode,
    parent: parent
  };
  // check inline-template render functions
  var inlineTemplate = vnode.data.inlineTemplate;
  if (isDef(inlineTemplate)) {
    options.render = inlineTemplate.render;
    options.staticRenderFns = inlineTemplate.staticRenderFns;
  }
  return new vnode.componentOptions.Ctor(options)
}

[iamareebjamal]

This prevents me from using buble in a vue project

Removing the comment from the line of last argument makes it transform correctly

[AngusFu]

@iamareebjamal As a solution for now, just exclude vue in buble plugin/loader options, since all files in vue/dist are pre-transpiled.

[chris-morgan]

Two minimised test cases:

function x(a//
){return{b:1,c:2}}

(a//
)=>({b:1,c:2})

In each case it improperly strips the comma after b:1, leaving b:1c:2. Looks to affect the first object literal with more than one element in the function, if the function has at least one argument and a line comment immediately before its arguments’ closing paren.

[anttikissa]

Bumped into a similar (same?) bug in https://github.com/rollup/rollup-plugin-buble/issues/13, from where I condensed another test case:

['x'].forEach(function () { } // this comment causes the bug
);

['x', 'y', 'z'].forEach(console.log)

If the comment "this comment causes the bug" is present, the result is ['x' 'y', 'z'].forEach(console.log). If the comment of stripped, it works. Bublé version 0.19.6.

It looks like this bug breaks not only Vue, but also the latest version of ReactDOM (https://unpkg.com/react-dom@16/umd/react-dom.development.js).

[anttikissa]

And like I mentioned in the other issue, my workaround for this for now: strip comments before running code through buble (in my case, using the rollup plugin rollup-plugin-cleanup).

[adrianheine]

Thanks for the report! I'm pretty sure this is an issue in my src/utils/removeTrailingComma.js.