minify: inlined variable declaration missing

[kryops]

Describe the bug

Hi there,

I noticed a regression in the swc minifier between version 1.3.105 and 1.3.106 when minifying the source of monaco-editor.

Maybe caused by #8542 ?

Unfortunately, I could not really make a very small minimal reproduction, as the problem goes away if I delete too much code. I created a gist containing the smallest reproduction I could manage.

Input code

// NOTE: Not really minimal reproduction,
// see https://gist.github.com/kryops/7869c6cc91483e346b4f362a9048a9a2

export function createTypeChecker() {
  function getFlowTypeOfReference(
    reference,
    declaredType,
    initialType = declaredType,
    flowContainer,
    flowNode = (_a2 => (_a2 = tryCast(reference, canHaveFlowNode)) == null ? void 0 : _a2.flowNode)()
  ) {
    // ...     
  }

  getFlowTypeOfReference()
}

Config

{
  "jsc": {
    "parser": {
      "syntax": "ecmascript",
      "jsx": false
    },
    "target": "es2020",
    "loose": true,
    "minify": {
      "compress": {
        "arguments": false,
        "arrows": true,
        "booleans": true,
        "booleans_as_integers": false,
        "collapse_vars": true,
        "comparisons": true,
        "computed_props": true,
        "conditionals": true,
        "dead_code": true,
        "directives": true,
        "drop_console": false,
        "drop_debugger": true,
        "evaluate": true,
        "expression": false,
        "hoist_funs": false,
        "hoist_props": true,
        "hoist_vars": false,
        "if_return": true,
        "join_vars": true,
        "keep_classnames": false,
        "keep_fargs": true,
        "keep_fnames": false,
        "keep_infinity": false,
        "loops": true,
        "negate_iife": true,
        "properties": true,
        "reduce_funcs": false,
        "reduce_vars": false,
        "side_effects": true,
        "switches": true,
        "typeofs": true,
        "unsafe": false,
        "unsafe_arrows": false,
        "unsafe_comps": false,
        "unsafe_Function": false,
        "unsafe_math": false,
        "unsafe_symbols": false,
        "unsafe_methods": false,
        "unsafe_proto": false,
        "unsafe_regexp": false,
        "unsafe_undefined": false,
        "unused": true,
        "const_to_let": true,
        "pristine_globals": true
      },
      "mangle": false
    }
  },
  "module": {
    "type": "es6"
  },
  "minify": false,
  "isModule": true
}

Playground link (or link to the minimal reproduction)

https://play.swc.rs/?version=1.3.106&code=H4sIAAAAAAAAA3VQsW6DMBTc%2FRVvBCnCKUE0INEOqFGnRKqyV455gBVjI%2FNIi6r8e02SKkuz2L7zvTufOYftbv%2BWw9YSOBRaT9ApozqhPeydrUZJypoF4xwGRGiJ%2BiHnvFEDRY2idjxE0nb86CbbD%2Fx5nWYylTJ7StYrXCXpIalXaSyyZbIWmYgZw%2B%2FeOoJ6NBdjkD6VcD%2F1WLYoj%2BiCEH4Y3AUN0kbbr1mxqz%2BwRodGYuAl4J94g4sLrFBq4bCatVfGVyEl9ExA8c997Z1La0gog%2B5ObW0164NPEUPxctuB3FSKgYJ7Kkhh3sUJN7eZMISiADNqDa9wsqqCJeTgp6M%2F1zAIfcq1IoD%2F1CiK5hN4fGZ%2BeVA3ZGf2Cw7%2BC%2FutAQAA&config=H4sIAAAAAAAAA32UO5LbMAyG%2Bz2FR3WKnS1S5ADpcgYOLYIyHZLQEKDXmh3fPRAlP7KG3En48AMkAOLrbbfrjtR3v3Zf8ik%2Foy0E5fYvFpoy27NYOuiTpb6EkbsfV3qkGXkbCZrpspCObRmAm4o%2B3j%2FeV0UXEQmuitWWQg5%2BeszZYxoLED3YxCoha4LM9L9%2BZQU%2FZ8ClPtr3iBFsfkGMJRMywwBFC9xjjHYkMCdblCjzSW0JhFqKGVYGZ8aCo8qzCxwwS85n6sA606MDBYUCPYcTaDLJJbJMcj3lPg072NdhaH3%2BpoaTjdWykhPOrSVyWiXqAQOx8TVrJVzgRg0WuBb3uzJ4U4Bryc%2B6I4a80ZO%2FAFKBaImyTaDFbR5e5mlL7V8qQ%2FYysjwpXOZbu2WGQYpqQvBKZefKQOGgdbOAqz3Mle2146x4o3wUHBjwXmZFCU2fgfuDlpSnEdArQPprvTZVCzC3V7jB5wfxAv%2BWW7I%2BYKtHsnzYpjSlPcYXCRLwAd0LB2kF4zYusiXO4zav2YGMBjjVpVIDz0tAHgCjiW1fPs2GPA%2BJaIaI%2B%2FuaWB0utz2cbB7u731ZxW%2BrQ5fQ1QbXJT%2F3d1nNP7u703UL3w7eBfpzVbakl3%2F06T5bMAYAAA%3D%3D

SWC Info output

No response

Expected behavior

The code executes without error.

Actual behavior

Runtime exception:

2963.js:1 Uncaught (in promise) ReferenceError: _a2 is not defined
    at getFlowTypeOfReference (ts.worker.js:250:846376)
    at checkIdentifier (ts.worker.js:250:874614)
    at checkExpressionWorker (ts.worker.js:250:1053957)
    ...

Version

1.3.106

Additional context

At the very top, swc@1.3.105 creates a var _a2 statement, which is missing from 1.3.106 on, causing the above exception.

Thanks for looking into it!

[kdy1]

I'm investigating, and #8523 seems to be the cause

[swc-bot]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.