<p dir="auto">This issue seems to occur only when using a computed property in generator/async function and running in loose mode:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="function *foo() {
  return {
    ['x']: null
  };
}"><pre class="notranslate"><code class="notranslate">function *foo() {
  return {
    ['x']: null
  };
}
</code></pre></div>
<p dir="auto">Compiles to:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="var marked0$0 = [foo].map(regeneratorRuntime.mark);
function foo() {
  return regeneratorRuntime.wrap(function foo$(context$1$0) {
    while (1) switch (context$1$0.prev = context$1$0.next) {
      case 0:
        return context$1$0.abrupt('return', (_ref = {}, _ref.x = null, _ref));

      case 1:
      case 'end':
        return context$1$0.stop();
    }
  }, marked0$0[0], this);
}"><pre class="notranslate"><code class="notranslate">var marked0$0 = [foo].map(regeneratorRuntime.mark);
function foo() {
  return regeneratorRuntime.wrap(function foo$(context$1$0) {
    while (1) switch (context$1$0.prev = context$1$0.next) {
      case 0:
        return context$1$0.abrupt('return', (_ref = {}, _ref.x = null, _ref));

      case 1:
      case 'end':
        return context$1$0.stop();
    }
  }, marked0$0[0], this);
}
</code></pre></div>
<p dir="auto">Note that <code class="notranslate">_ref</code> is used but never declared. With a regular function, this compiles correctly to:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="function foo() {
  var _ref;

  return (_ref = {}, _ref.x = null, _ref);
}"><pre class="notranslate"><code class="notranslate">function foo() {
  var _ref;

  return (_ref = {}, _ref.x = null, _ref);
}
</code></pre></div>
<p dir="auto">PS I couldn't figure out how to add this as a test case. Adding to <code class="notranslate">fixtures/esnext/es6-computed-properties</code> seems like the right thing, but how do I get this to compile in loose mode?</p>
<p dir="auto">Some guideline in <code class="notranslate">CONTRIBUTING.md</code> would help.</p>
<p dir="auto">Also, can't <code class="notranslate">make test</code> figure out all the dependencies (that it needs to build <code class="notranslate">lib/acorn</code>)?</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="function *x() {
    [].concat(...[])
}"><pre class="notranslate"><code class="notranslate">function *x() {
    [].concat(...[])
}
</code></pre></div>
<p dir="auto">--&gt;</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="function x() {
    return regeneratorRuntime.wrap(function x$(context$1$0) {
        while (1) switch (context$1$0.prev = context$1$0.next) {
            case 0:
                (_ref = []).concat.apply(_ref, []);

            case 1:
            case &quot;end&quot;:
                return context$1$0.stop();
        }
    }, marked0$0[0], this);
}"><pre class="notranslate"><code class="notranslate">function x() {
    return regeneratorRuntime.wrap(function x$(context$1$0) {
        while (1) switch (context$1$0.prev = context$1$0.next) {
            case 0:
                (_ref = []).concat.apply(_ref, []);

            case 1:
            case "end":
                return context$1$0.stop();
        }
    }, marked0$0[0], this);
}
</code></pre></div>
<p dir="auto">note the undeclared <code class="notranslate">_ref</code>.</p>
<p dir="auto">Previously: <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="53909538" data-permission-text="Title is private" data-url="https://github.com/babel/babel/issues/438" data-hovercard-type="issue" data-hovercard-url="/babel/babel/issues/438/hovercard" href="https://github.com/babel/babel/issues/438">#438</a>, <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="57874621" data-permission-text="Title is private" data-url="https://github.com/babel/babel/issues/803" data-hovercard-type="issue" data-hovercard-url="/babel/babel/issues/803/hovercard" href="https://github.com/babel/babel/issues/803">#803</a></p>