Regex support for format.comments of minifier

[DynamiteAndy]

Describe the feature

The current implementation of the minimizers format.comments does not allow regex to be used like https://webpack.js.org/plugins/terser-webpack-plugin/#preserve-comments

new TerserPlugin({
        terserOptions: {
          format: {
            comments: /@.* [\w|\d].*|==\/?UserScript==/i
          }
        }
      })

it instead requires either comments?: false | 'some' | 'all';, would like to propose supporting a regex so that certain comments will be left untouched

Babel plugin or link to the feature description

https://webpack.js.org/plugins/terser-webpack-plugin/#preserve-comments

Additional context

I raised this originally in the rspack repo but was told it can be sent here as well.

[lukpsaxo]

I've been tracking down why our bundle size increased by 10kb and the issue is we have a babel plugin that adds pure comments and then because of this: #9255

all of those comments now stay in the minified file.

I would love at least to be able to configure annotations to not be kept.

[kdy1]

@lukpsaxo It's supported. https://swc.rs/docs/configuration/minification#jscminifyformat
The unsupported thing is regex or function

[lukpsaxo]

@kdy1 I want to keep license comments and not keep pure annotations... I think that is not covered - at least the docs say only "some" and the code-change introducing the keeping of pure annotations didn't look like it was behind its own option (https://github.com/swc-project/swc/pull/9449/files#diff-1955969d1960346434767b5a39f0310edcab0f857933079e6048a50e67b65e38)

[abettadapur]

+1 to this
We have a very large project, and are blocked on upgrading SWC past 1.7.12 because the PURE comments adds multiple hundreds of KBs to our bundles

I don't need full regex support, but it would be great to preserve license comments and strip the PURE comments in the minifier, as they provide no value at runtime

[kdy1]

@lukpsaxo @abettadapur #9775 will add preserve_annotations to support removing PURE comments without stripping license comments

[DynamiteAndy]

Will this prevent the userscript headers from being removed?

Reason why I requested the regex is because that regex is what stops terser removing the userscript header