fix(issue#4354): unkown at-rule expression commas

packages/less/src/less/parser/parser.js

@@ -2217,7 +2217,7 @@ const Parser = function Parser(context, imports, fileInfo, currentIndex) {
                     parserInput.forget();
                     return new(tree.AtRule)(name, value, rules, index + currentIndex, fileInfo,
                         context.dumpLineNumbers ? getDebugInfo(index) : null,
-                        isRooted
+                        isRooted, undefined, hasUnknown
                     );
                 }
 

packages/less/src/less/tree/atrule.js

@@ -12,7 +12,8 @@ const AtRule = function(
     currentFileInfo,
     debugInfo,
     isRooted,
-    visibilityInfo
+    visibilityInfo,
+    hasUnknown
 ) {
     let i;
     var selectors = (new Selector([], null, null, this._index, this._fileInfo)).createEmptySelectors();
@@ -62,6 +63,7 @@ const AtRule = function(
     this.isRooted = isRooted || false;
     this.copyVisibilityInfo(visibilityInfo);
     this.allowRoot = true;
+    this.hasUnknown = hasUnknown;
 }
 
 AtRule.prototype = Object.assign(new Node(), {
@@ -135,7 +137,7 @@ AtRule.prototype = Object.assign(new Node(), {
 
         if (value) {
             value = value.eval(context);
-            if (value.value && this.keywordList(value.value)) {
+            if (!this.hasUnknown && value.value && this.keywordList(value.value)) {
                 value = new Anonymous(value.value.map(keyword => keyword.value).join(', '), this.getIndex(), this.fileInfo());
             }
         }

packages/test-data/css/_main/tailwind.css

@@ -0,0 +1,3 @@
+.box {
+  @apply h-64 w-64;
+}

packages/test-data/less/_main/tailwind.less

@@ -0,0 +1,3 @@
+.box {
+  @apply h-64 w-64;
+}