[css-mixins-1] Check default values against the parameter type (#12243)

andruud · Anders Hartvoll Ruud · web-flow · commit 35b2c3cb5a19 · 2025-06-06T15:37:57.000-07:00
Co-authored-by: Anders Hartvoll Ruud &lt;andruud@google.com&gt;
diff --git a/css-mixins-1/Overview.bs b/css-mixins-1/Overview.bs
@@ -201,11 +201,17 @@ and optionally a <dfn>default value</dfn>.
 	<<declaration-rule-list>>
 }
 
-<dfn><<function-parameter>></dfn> = <<custom-property-name>> <<css-type>>? [ : <<declaration-value>> ]?
+<dfn><<function-parameter>></dfn> = <<custom-property-name>> <<css-type>>? [ : <<default-value>> ]?
 <dfn><<css-type>></dfn> = <<syntax-component>> | <<type()>>
+<dfn><<default-value>></dfn> = <<declaration-value>>
 <dfn function lt="type()" for="@function">&lt;type()></dfn> = type( <<syntax>> )
 </pre>
 
+If a [=default value=] and a [=parameter type=] are both provided,
+then the [=default value=] must [=CSS/parse=] successfully
+according to that [=parameter type=]'s syntax.
+Otherwise, the ''@function'' rule is invalid.
+
 <h4 id=function-preamble>
 The Function Preamble</h4>
 

-Original file line number
+Diff line change
 	<>
+}
 -<> = <> <>? [ : <<declaration-value>> ]?
 +<> = <> <>? [ : <<default-value>> ]?
 <> = <> | <>
 +<> = <>
 <type()> = type( <> )
 +If a [=default value=] and a [=parameter type=] are both provided,
 +then the [=default value=] must [=CSS/parse=] successfully
 +according to that [=parameter type=]'s syntax.
 +Otherwise, the ''@function'' rule is invalid.
++
 The Function Preamble