Since canary version 15.2.1-canary.1 swc transpiller is wrong

[joacub]

Link to the code that reproduces this issue

not needed

To Reproduce

This issue has been occurring in the latest Canary release since 15.2.1-canary.1. The changes to the SWC compiler are breaking certain minification processes, causing crypto-js minification to fail. This happens because some variables are becoming undefined instead of being objects when attempting to assign values.

this code is tranpiling wrong:

 (function () {
    // Shortcuts
    var C = CryptoJS;
    var C_lib = C.lib;
    var WordArray = C_lib.WordArray;
    var C_algo = C.algo;
    var SHA256 = C_algo.SHA256;

    /**
     * SHA-224 hash algorithm.
     */
    var SHA224 = C_algo.SHA224 = SHA256.extend({
        _doReset: function () {
            this._hash = new WordArray.init([
                0xc1059ed8, 0x367cd507, 0x3070dd17, 0xf70e5939,
                0xffc00b31, 0x68581511, 0x64f98fa7, 0xbefa4fa4
            ]);
        },

        _doFinalize: function () {
            var hash = SHA256._doFinalize.call(this);

            hash.sigBytes -= 4;

            return hash;
        }
    });

    /**
     * Shortcut function to the hasher's object interface.
     *
     * @param {WordArray|string} message The message to hash.
     *
     * @return {WordArray} The hash.
     *
     * @static
     *
     * @example
     *
     *     var hash = CryptoJS.SHA224('message');
     *     var hash = CryptoJS.SHA224(wordArray);
     */
    C.SHA224 = SHA256._createHelper(SHA224);

is being transpiling to this:

(function () {
    // Shortcuts
    var a,b,c,d;

    var a = CryptoJS;
    var b = a.lib;
    var WordArray = C_lib.WordArray;
    var c = C.algo;
    var SHA256 = c.SHA256;
    /**
     * SHA-224 hash algorithm.
     */
    var SHA224 = b.SHA224 = SHA256.extend({
        _doReset: function () {
            this._hash = new WordArray.init([
                0xc1059ed8, 0x367cd507, 0x3070dd17, 0xf70e5939,
                0xffc00b31, 0x68581511, 0x64f98fa7, 0xbefa4fa4
            ]);
        },

        _doFinalize: function () {
            var hash = SHA256._doFinalize.call(this);

            hash.sigBytes -= 4;

            return hash;
        }
    });

    /**
     * Shortcut function to the hasher's object interface.
     *
     * @param {WordArray|string} message The message to hash.
     *
     * @return {WordArray} The hash.
     *
     * @static
     *
     * @example
     *
     *     var hash = CryptoJS.SHA224('message');
     *     var hash = CryptoJS.SHA224(wordArray);
     */
    d.SHA224 = SHA256._createHelper(SHA224);

where d is totally undefined or not initialized at all as an object

this is happening only in production

Current vs. Expected behavior

--

Provide environment information

Operating System:
  Platform: linux
  Arch: arm64
  Version: #60 SMP Tue Feb 18 19:55:47 UTC 2025
  Available memory (MB): 62236
  Available CPU cores: 16
Binaries:
  Node: 23.8.0
  npm: 11.1.0
  Yarn: N/A
  pnpm: 9.15.6
Relevant Packages:
  next: 15.2.1-canary.0 // There is a newer canary version (15.2.1-canary.4) available, please upgrade! 
  eslint-config-next: N/A
  react: 19.0.0
  react-dom: 19.0.0
  typescript: 5.8.2
Next.js Config:
  output: standalone
 ⚠ There is a newer canary version (15.2.1-canary.4) available, please upgrade! 
   Please try the latest canary version (`npm install next@canary`) to confirm the issue still exists before creating a new issue.
   Read more - https://nextjs.org/docs/messages/opening-an-issue

Which area(s) are affected? (Select all that apply)

Not sure

Which stage(s) are affected? (Select all that apply)

next build (local)

Additional context

No response

[github-actions]

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• How to Contribute to Open Source (Next.js)
• How to create a Minimal, Complete, and Verifiable example
• Reporting a Next.js bug
• Next.js Triaging issues