From 9937a5dcaa16e50b8c84b13baf63267c30774261 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Bj=C3=B8rn=20Erik=20Pedersen?=
 <bjorn.erik.pedersen@gmail.com>
Date: Tue, 16 Dec 2025 22:31:13 +0100
Subject: [PATCH] tpl/css: Deprecate libsass in favor of dartsass (note)

The upstream library is now EOL and the repo is archived. Also, it's time for us to move away from the extended CGO build and for Hugo users not already done that, move to https://gohugo.io/functions/css/sass/#dart-sass

https://github.com/sass/libsass

Closes #14261
---
 .../tocss/scss/scss_integration_test.go       | 23 +++++++++++++++++++
 tpl/css/css.go                                |  8 +++++--
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/resources/resource_transformers/tocss/scss/scss_integration_test.go b/resources/resource_transformers/tocss/scss/scss_integration_test.go
index 77c3ed37b..3955bcda5 100644
--- a/resources/resource_transformers/tocss/scss/scss_integration_test.go
+++ b/resources/resource_transformers/tocss/scss/scss_integration_test.go
@@ -462,3 +462,26 @@ target = "assets/sass"
 
 	b.AssertFileContent("public/index.html", ".foo1{color:red}.bar1{color:blue}.foo2{color:red}.bar2{color:blue}")
 }
+
+func TestLibsassDeprecatedIssue14261(t *testing.T) {
+	// This cannot be run in parallel because of global state in log deprecation handling.
+	if !scss.Supports() {
+		t.Skip()
+	}
+
+	files := `
+-- assets/scss/main.scss --
+body {
+	background-color: #fff;
+}
+-- hugo.toml --
+-- layouts/home.html --
+{{ $cssOpts := (dict  "transpiler" "libsass") }}
+{{ $r := resources.Get "scss/main.scss" |  toCSS $cssOpts  }}
+{{ $r.RelPermalink }}
+	`
+
+	b := hugolib.Test(t, files, hugolib.TestOptOsFs(), hugolib.TestOptInfo())
+
+	b.AssertLogContains("deprecated: css.Sass: libsass was deprecated in Hugo v0.153.0")
+}
diff --git a/tpl/css/css.go b/tpl/css/css.go
index ba21c8997..6ac37d6d8 100644
--- a/tpl/css/css.go
+++ b/tpl/css/css.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"sync"
 
+	"github.com/gohugoio/hugo/common/hugo"
 	"github.com/gohugoio/hugo/common/maps"
 	"github.com/gohugoio/hugo/common/paths"
 	"github.com/gohugoio/hugo/common/types/css"
@@ -91,7 +92,7 @@ func (ns *Namespace) Sass(args ...any) (resource.Resource, error) {
 		targetPath string
 		err        error
 		ok         bool
-		transpiler = sass.TranspilerLibSass
+		transpiler = sass.TranspilerLibSass // Deprecated default. Will be dartsass in future versions. See below.
 	)
 
 	r, targetPath, ok = resourcehelpers.ResolveIfFirstArgIsString(args)
@@ -106,7 +107,10 @@ func (ns *Namespace) Sass(args ...any) (resource.Resource, error) {
 	if m != nil {
 		if t, _, found := maps.LookupEqualFold(m, "transpiler"); found {
 			switch t {
-			case sass.TranspilerDart, sass.TranspilerLibSass:
+			case sass.TranspilerDart:
+				transpiler = cast.ToString(t)
+			case sass.TranspilerLibSass:
+				hugo.Deprecate("css.Sass: libsass", "Use dartsass instead. See https://gohugo.io/functions/css/sass/#dart-sass", "v0.153.0")
 				transpiler = cast.ToString(t)
 			default:
 				return nil, fmt.Errorf("unsupported transpiler %q; valid values are %q or %q", t, sass.TranspilerLibSass, sass.TranspilerDart)
-- 
2.39.5