Switch to SWC minifier by default

[devongovett]

This replaces Terser with the SWC minifier by default. In testing large real-world apps, we see a significant performance improvement of 15-20% with slightly smaller output as well. Since SWC supports the same configuration options as terser, it is a drop in replacement. Next.js recently enabled it by default as well, so it seems stable at this point.

Aside from switching the default config over, this also fixes a few tests that now have slightly different output, and converts errors to Parcel diagnostics.

[danieltroger]

FYI I had to switch back since my .terserrc is not supported:

{
  "mangle": {
    "eval": true,
    "properties": {
      "regex": "^(?!__core-js_shared__).*_$"
    }
  },
  "compress": {
    "unsafe": true,
    "arguments": true,
    "ecma": "2020",
    "passes": 4,
    "unsafe_arrows": true
  },
  "format": {
    "ecma": 2020
  }
}

[mischnic]

@danieltroger Please open a new issue with the actual error message about which property isn't supported. Ideally in the swc repo
swc already made some changes to support all terserrcs in the past: #9174, #9041

[danieltroger]

-> swc-project/swc#7754

[jboler]

When building my app with parcel 2.10.2 vs 2.8, my bundle is ~15% larger. I inspected the minified bundle and found that no comments were being removed at all.

I added this to a .terserrc and it removed most of the comments except some copyright comments:

{
  "format": {
    "comments": "some"
  }
}

Whereas parcel 2.8 would leave only the copyright/license comments by default. Is the intention to default to leaving comments in the minified bundle in parcel 2.10?

[devongovett]

Looks like there was a regression in SWC minifier recently. But appears to be fixed in the latest nightly version of @swc/core (in swc-project/swc#8257).