use collapse_vars causes compiled code logic changes

[runyuweng]

Bug report or feature request?
use collapse_vars causes compiled code logic changes

Uglify version (uglifyjs -V)
3.6.5

JavaScript input

var api = {
  getDataV1: function() {},
  getDataV2: function() {},
}
var fn;
var data;
if (typeId === 1) {
  fn = api.getDataV1;
  data = {id: 1};
} else {
  fn = api.getDataV2;
  data = {id: 2};
}
fn(data);

The uglifyjs CLI command executed or minify() options used.

  {
    mangle: true,
    compress: {}
  }

JavaScript output or error produced.

var fn,
  data,
  api = { getDataV1: function() {}, getDataV2: function() {} };
fn(
  (data =
    1 === typeId
      ? ((fn = api.getDataV1), { id: 1 })
      : ((fn = api.getDataV2), { id: 2 }))
);

JavaScript output when set collapse_vars fasle.

var fn,
  data,
  api = { getDataV1: function() {}, getDataV2: function() {} };
(data =
  1 === typeId
    ? ((fn = api.getDataV1), { id: 1 })
    : ((fn = api.getDataV2), { id: 2 })),
  fn(data);

demo url
https://github.com/runyuweng/uglify-js-compile-case

[alexlamsl]

Thanks for the detailed report - will investigate.

[alexlamsl]

Fix released in uglify-js@3.6.7