:global having only 1 selector is a BREAKING change

[snird]

Describe the bug

this: 8c3fb92

this breaks usable and known behavior.

Reproduction

every :global(.class1 .class2) or similar is now broken.

Logs

No response

System Info

npx: installed 1 in 0.816s

  System:
    OS: Linux 5.4 Ubuntu 20.04 LTS (Focal Fossa)
    CPU: (16) x64 AMD Ryzen 7 5800X 8-Core Processor
    Memory: 8.41 GB / 15.61 GB
    Container: Yes
    Shell: 5.0.16 - /bin/bash
  Binaries:
    Node: 14.17.0 - ~/.nvm/versions/node/v14.17.0/bin/node
    npm: 6.14.13 - ~/.nvm/versions/node/v14.17.0/bin/npm
  npmPackages:
    svelte: ^3.38.3 => 3.38.3

Severity

blocking all usage of svelte

[snird]

@ignatiusmb letting you know

[Conduitry]

For background: This was originally disallowed because #5907 was opened asking for different behavior in this situation that we didn't want to allow, and so we decided to make it a compiler error rather than have confusing behavior in that situation.

[ignatiusmb]

Thanks for letting me know. That commit is still unreleased, and your example :global(.class1 .class2) would still work, it will only throw a compile error on grouping selectors, which is only on selector list. Any other selector combinations should not be affected.

I see you're using the latest version, if what you meant is v3.38.3, then #6428 is the corresponding PR which is opened to close the issue linked above. I don't think it is necessarily "blocking all usage of svelte", and I think it's a good decision to disallow it as it doesn't really match what we expect as described in the issue. Although, I do agree that it might better released as v3.39.0 as it breaks most v3.38.x apps.

[jacobmischka]

In true semantic versioning it should have been a v4 change, but yes at least certainly a minor version if the major version is tied to marketing.

[snird]

It broke my usage of it, which isn't multiple selectors but refining a selector.
e.g .content .title.

I'm not even sure this PR intended to error on this kind of usage

[dummdidumm]

Please provide a reproducible code snippet with a complete CSS selector, not just parts of it. Both your given snippets don't give an error for me, so there must be more to it.

[jacobmischka]

I can confirm child selectors like above still work for me on the latest version as well.

[infuzz]

I confirm that this change throw an error when using MULTIPLE selectors in a list comma separated like this:
:global( div, p)
https://svelte.dev/repl/2eacdbae6cdc4a9f906516a9dbe7936d?version=3.38.3

Until 3.38.2 (https://svelte.dev/repl/2eacdbae6cdc4a9f906516a9dbe7936d?version=3.38.2) it was working well. This is breaking change for me since I use this in many components )-; and the doc does not specify this limitation.

[dummdidumm]

Your given code snippet is indeed something that would have worked correctly before and gave correct output. So I think we should - for semver reasons - revert the change for this specific case where the css selectors consists of a single :global only. @tanhauhau @Conduitry thoughts?

[Conduitry]

The specific case where :global() is the only thing in its selector is again allowed to contain multiple selectors in 3.39.0.