Fix less :extend format (#7984)

* Fix less `:extend` format

* Add changelog

* Add longer test

* Add issue link

* Style

* Fix changelog

changelog_unreleased/less/pr-7984.md

@@ -0,0 +1,30 @@
+#### Fix `:extend` format ([#7984](https://github.com/prettier/prettier/pull/7984) by [@fisker](https://github.com/fisker))
+
+<!-- prettier-ignore -->
+```less
+// Input
+.class {
+  &:extend(.some-class .some-other-class .some-very-loooooooooooooong-class all);
+}
+
+// Prettier stable
+.class {
+  &:extend(
+    .some-class .some-other-class .some-very-loooooooooooooong-class all
+  );
+}
+
+// Prettier stable (Second format)
+.class {
+  &: extend(
+    .some-class .some-other-class .some-very-loooooooooooooong-class all
+  );
+}
+
+// Prettier master
+.class {
+  &:extend(
+    .some-class .some-other-class .some-very-loooooooooooooong-class all
+  );
+}
+```

src/language-css/parser-postcss.js

@@ -375,6 +375,16 @@ function parseNestedCSS(node, options) {
       node.value = parseValue(value);
     }
 
+    // extend is missing
+    if (
+      isLessParser(options) &&
+      node.type === "css-decl" &&
+      !node.extend &&
+      value.startsWith("extend(")
+    ) {
+      node.extend = node.raws.between === ":";
+    }
+
     if (node.type === "css-atrule") {
       if (isLessParser(options)) {
         // mixin

tests/css_less/__snapshots__/jsfmt.spec.js.snap

@@ -1766,6 +1766,19 @@ label {
 // should not parse as custom-selector
 @custom-selector     :--icon #id;
 
+// extend #7977
+.class {
+  &:extend(.some-class .some-other-class .some-very-loooooooooooooong-class all);
+}
+.class {
+  &:extend(
+    .some-class .some-other-class .some-very-loooooooooooooong-class all
+  );
+}
+.class {
+  &:extend(.some-class .some-other-class .some-very-loooooooooooooong-class .some-very-loooooooooooooong-class all);
+}
+
 =====================================output=====================================
 @nice-blue: #5b83ad;
 @light-blue: @nice-blue + #111;
@@ -3378,6 +3391,24 @@ label {
 // should not parse as custom-selector
 @custom-selector: --icon #id;
 
+// extend #7977
+.class {
+  &:extend(
+    .some-class .some-other-class .some-very-loooooooooooooong-class all
+  );
+}
+.class {
+  &:extend(
+    .some-class .some-other-class .some-very-loooooooooooooong-class all
+  );
+}
+.class {
+  &:extend(
+    .some-class .some-other-class .some-very-loooooooooooooong-class
+      .some-very-loooooooooooooong-class all
+  );
+}
+
 ================================================================================
 `;
 

tests/css_less/less.less

@@ -1674,3 +1674,16 @@ label {
 
 // should not parse as custom-selector
 @custom-selector     :--icon #id;
+
+// extend #7977
+.class {
+  &:extend(.some-class .some-other-class .some-very-loooooooooooooong-class all);
+}
+.class {
+  &:extend(
+    .some-class .some-other-class .some-very-loooooooooooooong-class all
+  );
+}
+.class {
+  &:extend(.some-class .some-other-class .some-very-loooooooooooooong-class .some-very-loooooooooooooong-class all);
+}