René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[compiler] `IfExpression`s and `AssignmentExpression`s in loop bodies","articleBody":"## Problem\r\n`lightscript@0.5.9`:\r\n[Lscdiag](https://wcjohnson.github.io/lscdiag/?v=1\u0026s=eMOafVDDkU7DgzAMw7wVK0_CoMKVKV0pwrAOUMK_woAfYBMKwqnDm8KFwqVpSRzChMKow7rDrzjCg8KHPsONL8OnO8KfwqzCsyfDkcKab8KKHsKDwqgmw7HDlsKrMWFdw7dIwqpRwqQSw5Mfw7c_ZcOuw7JOchXDpsKuw5zDksODw6ZTwocoKsOyEcOnw6zCkmMSYcKIXmPDqmzDkMKiEsOtw5U1w5w8w68dQDt4wrBIYMOgCcOkwo7DoRHDssKEwqtVwpXDhgBfw4rDssOIwrTCoMKPwqhPw7_DolnDnsKwXizDuV_CjzbDoMOSVsKww612w4nDt05ww55oUhxSw698w7XCq8OMw6QhEwEtasOCw6ZlaDjCq8KLw5bCpsK7BsOXwprDrsO8woPCoR_CjUXDj8O5wq3DqcKOFMK0NyPDlXJdwq7Ct2LCnsOZa00gw552w6EXwod5w74FwqnDhW3Dsg#)\r\n```js\r\nf() -\u003e\r\n  for let i = 0; i \u003c 10; i++:\r\n    val = if check:\r\n      val2 = 3\r\n      val2\r\n    else:\r\n      val3 = 4\r\n      val3\r\n```\r\ncompiles to\r\n```js\r\nfunction f() {\r\n  for (let i = 0; i \u003c 10; i++) {\r\n    const val = check ? function () {\r\n      var _ret;\r\n\r\n      const val2 = 3;\r\n      _ret = val2;\r\n      return _ret;\r\n    }() : function () {\r\n      const val3 = 4;\r\n      return _ret = val3;\r\n    }();\r\n  }\r\n}\r\n```\r\n\r\nThe generated `_ret` var is not in scope in the second `function` block, so this code will crash with a no-undef error if `check` is false. However, it's a mystery to me why that `_ret` var is being generated at all.\r\n\r\nIf the enclosing `for` loop is removed, the problem goes away: [lscdiag](https://wcjohnson.github.io/lscdiag/?v=1\u0026s=eMOafU_DkU7DgzAMw7zClcOITyDClcKpWynCsErCoH7DgX7CgE0owqRuZ3DDky5xEMKiw4rCv8KTw6zCpW_Ds8KLw69OJ8O7bsKBwp5-JTjDtMOQLMOwMcOqOcOvwrYdUXTCp0VnZsK-wp7Dv8Oqwq3DnQ5lwprCisKew6rCvcK8w6wuw4YHaMOEBcKMw4Utw4cCfgrDjmBGw6wNNMOQw5_DncKrwofCt8KjVcOqR8KzelXDlCtzRsOzw51kw6kqw67CklrCrSwjZMKPwqvCoUrChsOHwpUdLcKkEMKBw7IPw5HCn8Kpw4p7WcKUwqcCPDIaw4HDrjB1KcKADcOMOcOsZHsawq7DhcKmcSZGwpdCMQ1nw7HDhsORLG3CucKpN3vCiDF5wpnCvMKkazcKwp5iw7wHwp_Dr2TCkQ)\r\n","author":{"url":"https://github.com/wcjohnson","@type":"Person","name":"wcjohnson"},"datePublished":"2017-09-24T21:02:44.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/47/lightscript/issues/47"}