SWC not throwing "SyntaxError: Identifier <x> has already been declared" when expected

[edwincoronado]

Hello everyone!

I have the following script:

export const superLongNameSoItMinimizes = () => {
  var superLongNameSoItMinimizes1 = "hello";
  console.log(superLongNameSoItMinimizes1);
};

export const superLongNameSoItMinimizes = () => {
  var superLongNameSoItMinimizes1 = "hello";
  console.log(superLongNameSoItMinimizes1);
};

export function superLongNameSoItMinimizes() {
  var superLongNameSoItMinimizes1 = "hello";
  console.log(superLongNameSoItMinimizes1);
}

With the following .swcrc file:

{
  "jsc": {
    "externalHelpers": true,
    "target": "es5",
    "loose": true,
    "parser": {
      "syntax": "ecmascript"
    }
  },
  "module": {
    "type": "commonjs",
    "strict": true,
    "strictMode": true
  },
  "sourceMaps": false
}

When I run SWC on the file I get the following output:

"use strict";
exports.superLongNameSoItMinimizes = superLongNameSoItMinimizes;
exports.superLongNameSoItMinimizes = void 0;
var superLongNameSoItMinimizes = function() {
    var superLongNameSoItMinimizes1 = "hello";
    console.log(superLongNameSoItMinimizes1);
};
exports.superLongNameSoItMinimizes = superLongNameSoItMinimizes;
var superLongNameSoItMinimizes = function() {
    var superLongNameSoItMinimizes1 = "hello";
    console.log(superLongNameSoItMinimizes1);
};
exports.superLongNameSoItMinimizes = superLongNameSoItMinimizes;
function superLongNameSoItMinimizes() {
    var superLongNameSoItMinimizes1 = "hello";
    console.log(superLongNameSoItMinimizes1);
}

I would expect a SyntaxError: Identifier superLongNameSoItMinimizes has already been declared error just as Babel/Node do. Is there a way to enforce these type of rules through a specific configuration? I'm using @swc/cli 0.1.52 and @swc/core 1.2.118.

Any help would be appreciated. Thanks!

[kwonoj]

I thought we are doing this check but seems not? This sounds like worth a filed bug to me.

[edwincoronado]

Thanks! Opened #2991