[mediaqueries-4] Need to describe how to serialize <general-enclosed> in mediaqueries.

[dbaron]

The syntax in mediaqueries-4 allows <general-enclosed> productions within mediaqueries.

The general serialization rules for mediaqueries are in cssom-1, but they cover mediaqueries-3.

I don't see anything in either that says how to serialize a mediaquery that contains a part parsed as <general-enclosed>. It looks like the Chromium implementation just serializes "as written" (probably with some tokenization normalization?), but it seems like this should be specified somewhere.

(This does have some interesting side effects; for example ((width)and (height)) is normalized in serialization to add the space before and, but ((width)and (height) or (color)) is not, because it's <general-enclosed>.)

It also seems like perhaps mediaqueries-4 should move the serialization rules out of cssom-1 and make the appropriate edits to them.

cc @andruud

[andruud]

What are the options?

• Serialize the tokens? (Although I'm not sure if specs define how that should happen in all aspects).
• Do the custom properties thing? ("Remember the exact original input string").
• Something else?

[cdoublev]

I repeat my point in #8735 (now closed) on serializing exactly as specified by the author.

Preserving a trailing comment before the ending token of a simple block, eg. @supports (width: 1px /* comment */), is also incompatible with the current tokenization algo, because it can only be part of the representation of the ending token ()): the algo repeatedly consume a token by consuming any comments before consuming following code point(s).

One solution I see would be to consume a run of comments or whitespaces before and after consuming a token, except after opening/ending tokens.

But this is not my preferred solution to serialize <declaration> and <any-value> (<general-enclosed>) because I think it is only required to not serialize --id: 1e0-foobar as --id: 1-foobar, ie. for custom property <declaration-value> (related: #6484).

Now there seems to be some beginning of cross-browser compat, to serialize exactly as specified, so I do not know.