Fix declaration-property-value-no-unknown false positives for attr() and if() (#8853)

jeddy3 · web-flow · commit 119097ea694c · 2025-11-27T17:45:25.000Z
diff --git a/.changeset/eight-garlics-complain.md b/.changeset/eight-garlics-complain.md
@@ -0,0 +1,5 @@
+---
+"stylelint": patch
+---
+
+Fixed: `declaration-property-value-no-unknown` false positives for `attr()`, `if()` and custom functions
diff --git a/lib/rules/declaration-property-value-no-unknown/__tests__/index.mjs b/lib/rules/declaration-property-value-no-unknown/__tests__/index.mjs
@@ -93,6 +93,14 @@ testRule({
 			code: '@font-face { font-weight: bolder; }',
 			description: 'ignore descriptors with unknown values',
 		},
+		{
+			code: 'a { color: if(media(all): red;); }',
+			description: 'ignore csstree parse errors for `if()` function',
+		},
+		{
+			code: 'a { content: attr(data-foo type(<string>)) }',
+			description: 'ignore csstree parse errors for `attr()` function',
+		},
 		{
 			code: stripIndent`
 				a { font-weight: bolder; }
diff --git a/lib/rules/declaration-property-value-no-unknown/index.cjs b/lib/rules/declaration-property-value-no-unknown/index.cjs
diff --git a/lib/rules/declaration-property-value-no-unknown/index.mjs b/lib/rules/declaration-property-value-no-unknown/index.mjs
@@ -156,6 +156,10 @@ const rule = (primary, secondaryOptions) => {
 
 				if (containsUnsupportedFunction(cssTreeValueNode)) return;
 			} catch {
+				// Ignore parse errors for `attr()`, `if()` and custom functions
+				// See: https://github.com/stylelint/stylelint/issues/8779
+				if (/(?:^|[^\w-])(?:attr|if|--[\w-]+)\(/i.test(value)) return;
+
 				const index = declarationValueIndex(decl);
 				const endIndex = index + value.length;
 

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +"stylelint": patch
 +---
++
 +Fixed: `declaration-property-value-no-unknown` false positives for `attr()`, `if()` and custom functions