Cannot use another parser with transformer eslint v4

[bradzacher]

Describe the bug When selecting the ESLint v4 transformer, it automatically switches to the babel-eslint parser.

If you switch the parser to @typescript-eslint/parser after this, it doesn't change the parser used in the transform.

To Reproduce Example: https://astexplorer.net/#/gist/a6c718c40c7797b1e7d071e2180c35ad/a56db076715dc493620243af71bf20cb7ed2e497

Repro steps:

1. parse javascript with @typescript-eslint/parser
2. turn on transform to ESLint v4
   • observe the parser switch to babel-eslint
3. create example and transformer as in the above example
4. switch parser back to to @typescript-eslint/parser
   • observe the AST output pane shows the correct AST.

Expected behavior Transform output should start with:

// "TS" TypeAlias (at 1:1)

Actual behavior Transform output instead starts with:

// "Babel" TypeAlias (at 1:1)

Browser (please complete the following information):

• OS: macos 10.14.6
• Browser: chrome
• 80.0.3973.0 (Official Build) canary (64-bit)

astexplorer settings:

• Selected parser: @typescript-eslint/parser
• Selected transformer (if applicable): ESLint v4
• Contents of the local storage key explorerSettingsV1 (code can be removed if you don't want it to be public)

{
    "showTransformPanel": false,
    "parserSettings": {},
    "parserPerCategory": {},
    "workbench": {
        "parser": "acorn",
        "code": "/**\n * Paste or drop some JavaScript here and explore\n * the syntax tree created by chosen parser.\n * You can use all the cool new features from ES6\n * and even more. Enjoy!\n */\n\nlet tips = [\n  \"Click on any AST node with a '+' to expand it\",\n\n  \"Hovering over a node highlights the \\\n   corresponding part in the source code\",\n\n  \"Shift click on an AST node expands the whole substree\"\n];\n\nfunction printTips() {\n  tips.forEach((tip, i) => console.log(`Tip ${i}:` + tip));\n}\n",
        "keyMap": "default",
        "transform": {
            "code": "",
            "transformer": null
        }
    }
}

Additional context Add any other context about the problem here.

[fkling]

Unfortunately this works "as designed". The selected parser isn't connected to the selected transformer at all. I have plans to change this though.