Only one CSS-wide keywords can exist in the property value

[yisibl]

Invalid value

Should throw an error, but it doesn't now.

.Invalid {
	animation-name: default, two;
	animation-name: one, initial;
	animation-name: one, inherit;
	animation-name: one, unset;
	animation-name: revert, three;
	animation-name: revert-layer, four;
	animation-name: "foo", unset;
	animation-name: unset, "foo";
}

Valid value

.Valid {
	animation-name: none, none;
	animation-name: one, none;
	animation-name: "foo", none;
	animation-name: none, "foo";
}

csstree output

 syntax: [ none | <keyframes-name> ]#
  animation-name: "foo",unset
  ----------------------^

Theoretically, any property that supports multiple values, except for the animation-name property, needs to be handled this way. For details, see: web-platform-tests/wpt@4f82d32

[devongovett]

Anything that uses the CustomIdent::parse function should already exclude default. animation-name seemed to be an outlier. I updated it in the above commit.

Currently, if an error is thrown during parsing of a property value, it falls back to being stored as raw tokens, so the error won't be shown to the user. Eventually, we might have a strict mode for this. But added a test to show AnimationName::parse failing on this.

[yisibl]

Please reopen this issue, it looks like it only supports animation-name: <string> for now. The core point of this issue is to throw errors for CSS-wide keywords.

[devongovett]

As I tried to explain, that's because when an error occurs it falls back to storing the tokens. A strict mode where errors are emitted instead is not specific to animation name.

[devongovett]

See here: https://github.com/parcel-bundler/lightningcss/blob/master/src/properties/mod.rs#L564

This is mainly so that if new syntax is added that we don't support yet, we don't fail the build but pass it through unmodified.