From dd7e0d7d2b41bf5a177e20ec084245034ee4133c Mon Sep 17 00:00:00 2001
From: Puneet Dixit <236133619+puneetdixit200@users.noreply.github.com>
Date: Thu, 21 May 2026 20:38:01 +0530
Subject: [PATCH] Preserve container feature function spacing

Signed-off-by: Puneet Dixit <236133619+puneetdixit200@users.noreply.github.com>
---
 packages/less/lib/less/parser/parser.js       | 23 +++++++--
 .../tests-unit/container/container.css        | 40 ++++++++++++++++
 .../tests-unit/container/container.less       | 48 +++++++++++++++++++
 3 files changed, 107 insertions(+), 4 deletions(-)

diff --git a/packages/less/lib/less/parser/parser.js b/packages/less/lib/less/parser/parser.js
index 6a439fb89..1bd114192 100644
--- a/packages/less/lib/less/parser/parser.js
+++ b/packages/less/lib/less/parser/parser.js
@@ -1878,7 +1878,7 @@ const Parser = function Parser(context, imports, fileInfo, currentIndex) {
                 parserInput.save();
                 do {
                     parserInput.save();
-                    if (parserInput.$re(/^[0-9a-z-]*\s+\(/)) {
+                    if (parserInput.$re(/^(?:--|-?(?:[_a-zA-Z0-9]|[^\0-\x7F]|\\[0-9a-fA-F]{1,6}\s?|\\[^\n\r\f0-9a-fA-F]))(?:[-_a-zA-Z0-9]|[^\0-\x7F]|\\[0-9a-fA-F]{1,6}\s?|\\[^\n\r\f0-9a-fA-F])*\s+\(/)) {
                         spacing = true;
                     }
                     parserInput.restore();
@@ -1920,7 +1920,11 @@ const Parser = function Parser(context, imports, fileInfo, currentIndex) {
                         }
                         if (closed) {
                             if (p && !e) {
-                                nodes.push(new (tree.Paren)(new (tree.QueryInParens)(p.op, p.lvalue, p.rvalue, rangeP ? rangeP.op : null, rangeP ? rangeP.rvalue : null, p._index)));
+                                const paren = new (tree.Paren)(new (tree.QueryInParens)(p.op, p.lvalue, p.rvalue, rangeP ? rangeP.op : null, rangeP ? rangeP.rvalue : null, p._index));
+                                if (!spacing) {
+                                    paren.noSpacing = true;
+                                }
+                                nodes.push(paren);
                                 e = p;
                             } else if (p && e) {
                                 nodes.push(new (tree.Paren)(new (tree.Declaration)(p, e, null, null, parserInput.i + currentIndex, fileInfo, true)));
@@ -1929,7 +1933,11 @@ const Parser = function Parser(context, imports, fileInfo, currentIndex) {
                                 }
                                 spacing = false;
                             } else if (e) {
-                                nodes.push(new(tree.Paren)(e));
+                                const paren = new(tree.Paren)(e);
+                                if (!spacing) {
+                                    paren.noSpacing = true;
+                                }
+                                nodes.push(paren);
                                 spacing = false;
                             } else {
                                 error('badly formed media feature definition');
@@ -1942,7 +1950,14 @@ const Parser = function Parser(context, imports, fileInfo, currentIndex) {
 
                 parserInput.forget();
                 if (nodes.length > 0) {
-                    return new(tree.Expression)(nodes);
+                    const expression = new(tree.Expression)(nodes);
+                    if (nodes.length === 2
+                        && (nodes[0].type === 'Keyword' || nodes[0].type === 'Variable')
+                        && nodes[1].type === 'Paren'
+                        && nodes[1].noSpacing) {
+                        expression.noSpacing = true;
+                    }
+                    return expression;
                 }
             },
 
diff --git a/packages/test-data/tests-unit/container/container.css b/packages/test-data/tests-unit/container/container.css
index dd9673c7e..70fb096f8 100644
--- a/packages/test-data/tests-unit/container/container.css
+++ b/packages/test-data/tests-unit/container/container.css
@@ -130,6 +130,41 @@
     margin: 0.5em 0 0 0;
   }
 }
+@container card (width > 400px), style(--responsive: true), scroll-state(stuck: top) {
+  h2 {
+    font-size: 1.5em;
+  }
+}
+@container style(--theme) {
+  .style-query {
+    color: red;
+  }
+}
+@container style((--theme: one) or (--theme: two)) {
+  .style-query-list {
+    color: blue;
+  }
+}
+@container contactBody (min-width: 1300px) {
+  .named-container {
+    width: 25%;
+  }
+}
+@container _body (min-width: 1300px) {
+  .underscored-container {
+    width: 25%;
+  }
+}
+@container --body (min-width: 1300px) {
+  .custom-ident-container {
+    width: 25%;
+  }
+}
+@container contact\.body (min-width: 1300px) {
+  .escaped-container {
+    width: 25%;
+  }
+}
 @container (width < 500px) or (height < 500px) and (orientation: portrait) {
   .card-content p {
     padding: 0;
@@ -268,6 +303,11 @@
     font-size: 75%;
   }
 }
+@container sidebar (min-width: 400px), scroll-state(stuck: top) {
+  #sticky-child {
+    font-size: 80%;
+  }
+}
 @container foo (min-width: 400px) {
   #sticky-child {
     font-size: 75%;
diff --git a/packages/test-data/tests-unit/container/container.less b/packages/test-data/tests-unit/container/container.less
index 013a9e243..9d1dcd714 100644
--- a/packages/test-data/tests-unit/container/container.less
+++ b/packages/test-data/tests-unit/container/container.less
@@ -159,6 +159,48 @@
     }
 }
 
+@container card (width > 400px), style(--responsive: true), scroll-state(stuck: top) {
+    h2 {
+        font-size: 1.5em;
+    }
+}
+
+@container style(--theme) {
+    .style-query {
+        color: red;
+    }
+}
+
+@container style((--theme: one) or (--theme: two)) {
+    .style-query-list {
+        color: blue;
+    }
+}
+
+@container contactBody (min-width: 1300px) {
+    .named-container {
+        width: 25%;
+    }
+}
+
+@container _body (min-width: 1300px) {
+    .underscored-container {
+        width: 25%;
+    }
+}
+
+@container --body (min-width: 1300px) {
+    .custom-ident-container {
+        width: 25%;
+    }
+}
+
+@container contact\.body (min-width: 1300px) {
+    .escaped-container {
+        width: 25%;
+    }
+}
+
 @container ( width < 500px ) or (height<500px) and (orientation: portrait) {
     .card-content p {
         padding: 0;
@@ -319,6 +361,12 @@
     }
 }
 
+@container sidebar (min-width: 400px), scroll-state(stuck: top) {
+    #sticky-child {
+      font-size: 80%;
+    }
+}
+
 @varfoo: foo;
 @threshold: 400px;
 @container @varfoo (min-width: @threshold) {