From 4f1c4d9eb85fe6afb925cc0d57de7f28e786cabe Mon Sep 17 00:00:00 2001
From: Konv Suu <2583695112@qq.com>
Date: Fri, 26 Dec 2025 16:24:35 +0800
Subject: [PATCH] Prevent SCSS math expressions in group treated as map item
 (#18530)

---
 changelog_unreleased/scss/18530.md            | 18 ++++
 src/language-css/utilities/index.js           |  5 +
 tests/format/scss/math/7419.scss              | 15 +++
 .../math/__snapshots__/format.test.js.snap    | 94 +++++++++++++++++++
 4 files changed, 132 insertions(+)
 create mode 100644 changelog_unreleased/scss/18530.md
 create mode 100644 tests/format/scss/math/7419.scss

diff --git a/changelog_unreleased/scss/18530.md b/changelog_unreleased/scss/18530.md
new file mode 100644
index 000000000..55bd402d1
--- /dev/null
+++ b/changelog_unreleased/scss/18530.md
@@ -0,0 +1,18 @@
+#### Prevent adding trailing comma in math expression within function arguments (#18530 by @kovsu)
+
+<!-- prettier-ignore -->
+```scss
+// Input
+@include container($foo: 2 * ($bar + $baz));
+
+// Prettier stable
+@include container(
+  $foo: 2 *
+    (
+      $bar + $baz,
+    )
+);
+
+// Prettier main
+@include container($foo: 2 * ($bar + $baz));
+```
diff --git a/src/language-css/utilities/index.js b/src/language-css/utilities/index.js
index 1d71d087d..b8595300f 100644
--- a/src/language-css/utilities/index.js
+++ b/src/language-css/utilities/index.js
@@ -292,6 +292,11 @@ function isSCSSMapItemNode(path, options) {
 
   // List as value of key inside SCSS map (i.e. `$map: (key: (value other-value other-other-value))`)
   if (isKeyValuePairInParenGroupNode(parentParentNode)) {
+    // If there is any operator in the value, it is not a map item
+    if (parentNode.groups.some((node) => isMathOperatorNode(node))) {
+      return false;
+    }
+
     return true;
   }
 
diff --git a/tests/format/scss/math/7419.scss b/tests/format/scss/math/7419.scss
new file mode 100644
index 000000000..308e98725
--- /dev/null
+++ b/tests/format/scss/math/7419.scss
@@ -0,0 +1,15 @@
+@include container($foo: 2);
+@include container($foo: 2 * ($bar));
+@include container($foo: 2 * ($bar + $baz));
+
+@include container($foo: 1, $bar: 2);
+
+@include container($foo: (
+  $bar,
+  $baz
+));
+
+@include container($foo: (
+  $bar + $baz,
+  $qux * 2
+));
diff --git a/tests/format/scss/math/__snapshots__/format.test.js.snap b/tests/format/scss/math/__snapshots__/format.test.js.snap
index 44f1f6726..36601328b 100644
--- a/tests/format/scss/math/__snapshots__/format.test.js.snap
+++ b/tests/format/scss/math/__snapshots__/format.test.js.snap
@@ -523,3 +523,97 @@ $colors: (
 
 ================================================================================
 `;
+
+exports[`7419.scss - {"trailingComma":"es5"} format 1`] = `
+====================================options=====================================
+parsers: ["scss"]
+printWidth: 80
+trailingComma: "es5"
+                                                                                | printWidth
+=====================================input======================================
+@include container($foo: 2);
+@include container($foo: 2 * ($bar));
+@include container($foo: 2 * ($bar + $baz));
+
+@include container($foo: 1, $bar: 2);
+
+@include container($foo: (
+  $bar,
+  $baz
+));
+
+@include container($foo: (
+  $bar + $baz,
+  $qux * 2
+));
+
+=====================================output=====================================
+@include container($foo: 2);
+@include container($foo: 2 * ($bar));
+@include container($foo: 2 * ($bar + $baz));
+
+@include container($foo: 1, $bar: 2);
+
+@include container(
+  $foo: (
+    $bar,
+    $baz,
+  )
+);
+
+@include container(
+  $foo: (
+    $bar + $baz,
+    $qux * 2,
+  )
+);
+
+================================================================================
+`;
+
+exports[`7419.scss - {"trailingComma":"none"} format 1`] = `
+====================================options=====================================
+parsers: ["scss"]
+printWidth: 80
+trailingComma: "none"
+                                                                                | printWidth
+=====================================input======================================
+@include container($foo: 2);
+@include container($foo: 2 * ($bar));
+@include container($foo: 2 * ($bar + $baz));
+
+@include container($foo: 1, $bar: 2);
+
+@include container($foo: (
+  $bar,
+  $baz
+));
+
+@include container($foo: (
+  $bar + $baz,
+  $qux * 2
+));
+
+=====================================output=====================================
+@include container($foo: 2);
+@include container($foo: 2 * ($bar));
+@include container($foo: 2 * ($bar + $baz));
+
+@include container($foo: 1, $bar: 2);
+
+@include container(
+  $foo: (
+    $bar,
+    $baz
+  )
+);
+
+@include container(
+  $foo: (
+    $bar + $baz,
+    $qux * 2
+  )
+);
+
+================================================================================
+`;