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"Block-scoped variable used before its declaration" not detected inside closures #9273

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@kourge

Description

@kourge

This is similar to #7477 and #8976, but occurs inside closures.

TypeScript Version:

1.9.0-dev.20160620-1.0

Code

const y = (() => x)();
const x = 3;

Expected behavior:

The compilation error "Block-scoped variable x used before its declaration".

Actual behavior:

The code is compiled to:

var y = (function () { return x; })();
var x = 3;

This sets y to undefined.

Additional variants:

This also occurs when the access to the binding x is in default argument value position:

const y = ((i: number = x) => i)();
const x = 3;

Comparison against spec behavior:
All of the following result in a ReferenceError being thrown on Node 5.1:

(function() {
  'use strict';
  var y = (() => x)();
  const x = 3;
  return y;
})();

(function() {
  'use strict';
  const y = (() => x)();
  const x = 3;
  return y;
})();

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