Treeshaking of arguments leads to SyntaxError

[manucorporat]

• Rollup Version: 1.14.4
• Operating System (or Browser): osx and browser
• Node Version: 12.0.0

How Do We Reproduce?

https://rollupjs.org/repl?version=1.14.4&shareable=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

Expected Behavior

It should generate valid JS:

Actual Behavior

It does generate JS with syntax errors:

function writeGeometry(geometry, opt_options) {
  return writePointGeometry((geometry);
}

^ notice the missing closing ) after geometry).

Real world

This issue was first reported by an user of stencil when trying to use the ol (open layers) https://www.npmjs.com/package/ol package.

ionic-team/stencil#1607

Specifically this piece of the code:

function writePointGeometry(geometry, opt_options) {
  return {
    type: 'Point',
    coordinates: geometry.getCoordinates()
  };
}
function writeGeometry(geometry, opt_options) {
  geometry = /** @type {import("../geom/Geometry.js").default} */ (transformWithOptions(geometry, true, opt_options));
  var type = geometry.getType();

  /** @type {GeoJSONGeometry} */
  var geoJSON;
  switch (type) {
    case GeometryType.POINT: {
      geoJSON = writePointGeometry(/** @type {Point} */ (geometry), opt_options);
      break;
    }
 }
}

      geoJSON = writePointGeometry(/** @type {Point} */ (geometry), opt_options);

[manucorporat]

Error seems related with acornjs/acorn#136

[manucorporat]

The argument's start/end does not include the surrounding parentheses, looking into a solution...

[manucorporat]

Looks like this could be a problem for any expression surrounded by parentheses:

This seems like a odd behaviour from acorn

[manucorporat]

I think the solution could be to set preserveParens: true in the acorn's settings, but that would require to fix a lot of parts of rollup

[lukastaegert]

I was thinking about that, but I agree it would shake many things up and it would create a non-standard syntax tree. Meanwhile I found a simpler solution, which is to just find the next "," after the argument :) PR upcoming

[lukastaegert]

Fix at #2910

[manucorporat]

@lukastaegert damn! pushed a PR 30 seconds ago
#2911

[manucorporat]

same fix!!! haha