Custom properties are not replaced with their values when preserve: false

[ZauberNerd]

Bug description

Since postcss-custom-properties 12.1.9 custom properties are not correctly replaced in some cases, while still removing their declaration when setting preserve: false.

This leads to generated CSS that contains a reference to a custom property, but not the custom property itself, thus causing it not to be applied.

This bug seems to be introduced by: #620, which was caused by: #619

Source CSS

:root {
  --some-value: red;
}

body {
  color: red; /* fallback for browsers that do not support custom properties */
  color: var(--some-value);
}

Expected CSS

body {
  color: red;
}

/* or maybe even repeating the color declaration, like postcss-custom-properties@12.1.8 did */
body {
  color: red;
  color: red;
}

Actual CSS

body {
  color: red; /* fallback for browsers that do not support custom properties */
  color: var(--some-value);
}

Does it happen with npx @csstools/csstools-cli <plugin-name> minimal-example.css?

Yes

Debug output

No response

Extra config

npx @csstools/csstools-cli postcss-custom-properties minimal-example.css -p '{"preserve":false}'

What plugin are you experiencing this issue on?

PostCSS Custom Properties

Plugin version

12.1.9

What OS are you experiencing this on?

Linux

Node Version

18.11.0

Validations

• Follow our Code of Conduct
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

Would you like to open a PR for this bug?

• I'm willing to open a PR

[romainmenke]

Hi @ZauberNerd thank you for reaching out!

We indeed overlooked this pattern in 12.1.9.
A fix has been prepared and we will try to make available shortly : #662

[romainmenke]

@ZauberNerd The fix was just released : https://github.com/csstools/postcss-plugins/blob/99a0d34b0694daf59d7d9f7f1c8e517109d267db/plugins/postcss-custom-properties/CHANGELOG.md#12110-october-20-2022

Can you let us know if this fully resolves your issue?

[ZauberNerd]

Wow, this was really fast. I'm on my way into the weekend, so I'll check on Monday morning

[ZauberNerd]

@romainmenke thanks for fixing this. It works again!

[romainmenke]

@ZauberNerd Thank you for verifying 🎉