Add Dart Sass support

But note that the Dart Sass Embedded Protocol is still in beta (beta 5), a main release scheduled for Q1 2021.

Fixes gohugoio#7380

.travis.yml

@@ -46,13 +46,25 @@ cache:
     - $HOME/AppData/Local/go-build
 
 before_install:
+  - mkdir -p $HOME/bin
+  - export PATH="$HOME/bin":"$PATH";
+  - echo "Home is $HOME";
   - df -h
-    # https://travis-ci.community/t/go-cant-find-gcc-with-go1-11-1-on-windows/293/5
   - if [ "$TRAVIS_OS_NAME" = "windows" ]; then
         choco install mingw -y;
         choco install -y --force nodejs;
+        curl -LJO https://github.com/sass/dart-sass-embedded/releases/download/1.0.0-beta.5/sass_embedded-1.0.0-beta.5-windows-x64.zip;
+        unzip sass_embedded-1.0.0-beta.5-windows-x64.zip -d $HOME/bin;
         export PATH=/c/tools/mingw64/bin:"$PATH";
     fi
+  - if [ "$TRAVIS_OS_NAME" = "osx" ]; then
+        curl -LJO https://github.com/sass/dart-sass-embedded/releases/download/1.0.0-beta.5/sass_embedded-1.0.0-beta.5-macos-x64.tar.gz;
+        tar -xvf sass_embedded-1.0.0-beta.5-macos-x64.tar.gz -C $HOME/bin;
+    fi
+  - if [ "$TRAVIS_OS_NAME" = "linux" ]; then
+        curl -LJO https://github.com/sass/dart-sass-embedded/releases/download/1.0.0-beta.5/sass_embedded-1.0.0-beta.5-linux-x64.tar.gz;
+        tar -xvf sass_embedded-1.0.0-beta.5-linux-x64.tar.gz -C $HOME/bin;
+    fi
   - gem install asciidoctor
   - type asciidoctor
 

common/herrors/error_locator.go

@@ -70,7 +70,7 @@ func (e ErrorContext) Position() text.Position {
 
 var _ causer = (*ErrorWithFileContext)(nil)
 
-// ErrorWithFileContext is an error with some additional file context related
+// ErrorWithFileCoxntext is an error with some additional file context related
 // to that error.
 type ErrorWithFileContext struct {
 	cause error

deps/deps.go

@@ -94,6 +94,9 @@ type Deps struct {
 	// BuildStartListeners will be notified before a build starts.
 	BuildStartListeners *Listeners
 
+	// Resources that gets closed when the build is done or the server shuts down.
+	BuildClosers *Closers
+
 	// Atomic values set during a build.
 	// This is common/global for all sites.
 	BuildState *BuildState
@@ -284,6 +287,7 @@ func New(cfg DepsCfg) (*Deps, error) {
 		Site:                    cfg.Site,
 		FileCaches:              fileCaches,
 		BuildStartListeners:     &Listeners{},
+		BuildClosers:            &Closers{},
 		BuildState:              buildState,
 		Running:                 cfg.Running,
 		Timeout:                 time.Duration(timeoutms) * time.Millisecond,
@@ -297,6 +301,10 @@ func New(cfg DepsCfg) (*Deps, error) {
 	return d, nil
 }
 
+func (d *Deps) Close() error {
+	return d.BuildClosers.Close()
+}
+
 // ForLanguage creates a copy of the Deps with the language dependent
 // parts switched out.
 func (d Deps) ForLanguage(cfg DepsCfg, onCreated func(d *Deps) error) (*Deps, error) {
@@ -399,3 +407,28 @@ func (b *BuildState) Incr() int {
 func NewBuildState() BuildState {
 	return BuildState{}
 }
+
+type Closer interface {
+	Close() error
+}
+
+type Closers struct {
+	mu sync.Mutex
+	cs []Closer
+}
+
+func (cs *Closers) Add(c Closer) {
+	cs.mu.Lock()
+	defer cs.mu.Unlock()
+	cs.cs = append(cs.cs, c)
+}
+
+func (cs *Closers) Close() error {
+	cs.mu.Lock()
+	defer cs.mu.Unlock()
+	for _, c := range cs.cs {
+		c.Close()
+	}
+
+	return nil
+}

docs/content/en/hugo-pipes/scss-sass.md

@@ -24,14 +24,19 @@ Any SASS or SCSS file can be transformed into a CSS file using `resources.ToCSS`
 ```
 
 ### Options
+
+transpiler [string] {{< new-in "0.80.0" >}}
+
+: The `transpiler` to use, valid values are `libsass` (default) and `dartsass`. Note that the Embedded Dart Sass project is still in beta (beta 5 at the time of writing). The release is scheduled for Q1 2021. We will try to improve the installation process by then, but if you want to use Hugo with Dart Sass you need to download a release binary from [Embedded Dart Sass](https://github.com/sass/dart-sass-embedded/releases) and make sure it's in your PC's `$PATH` (or `%PATH%` on Windows).
+
 targetPath [string]
 : If not set, the resource's target path will be the asset file original path with its extension replaced by `.css`.
 
 outputStyle [string]
 : Default is `nested`. Other available output styles are `expanded`, `compact` and `compressed`.
 
 precision [int]
-: Precision of floating point math.
+: Precision of floating point math. **Note:** This option is not supported by Dart Sass.
 
 enableSourceMap [bool]
 : When enabled, a source map will be generated.

go.mod

@@ -11,6 +11,7 @@ require (
 	github.com/aws/aws-sdk-go v1.35.0
 	github.com/bep/debounce v1.2.0
 	github.com/bep/gitmap v1.1.2
+	github.com/bep/godartsass v0.8.0
 	github.com/bep/golibsass v0.7.0
 	github.com/bep/tmc v0.5.1
 	github.com/cli/safeexec v1.0.0

go.sum

@@ -134,6 +134,8 @@ github.com/bep/debounce v1.2.0 h1:wXds8Kq8qRfwAOpAxHrJDbCXgC5aHSzgQb/0gKsHQqo=
 github.com/bep/debounce v1.2.0/go.mod h1:H8yggRPQKLUhUoqrJC1bO2xNya7vanpDl7xR3ISbCJ0=
 github.com/bep/gitmap v1.1.2 h1:zk04w1qc1COTZPPYWDQHvns3y1afOsdRfraFQ3qI840=
 github.com/bep/gitmap v1.1.2/go.mod h1:g9VRETxFUXNWzMiuxOwcudo6DfZkW9jOsOW0Ft4kYaY=
+github.com/bep/godartsass v0.8.0 h1:zPQlC+yfX5wZIPZbvEcN6+4XWfr4BH6EvFRXnOC0Wic=
+github.com/bep/godartsass v0.8.0/go.mod h1:nXQlHHk4H1ghUk6n/JkYKG5RD43yJfcfp5aHRqT/pc4=
 github.com/bep/golibsass v0.7.0 h1:/ocxgtPZ5rgp7FA+mktzyent+fAg82tJq4iMsTMBAtA=
 github.com/bep/golibsass v0.7.0/go.mod h1:DL87K8Un/+pWUS75ggYv41bliGiolxzDKWJAq3eJ1MA=
 github.com/bep/tmc v0.5.1 h1:CsQnSC6MsomH64gw0cT5f+EwQDcvZz4AazKunFwTpuI=
@@ -262,6 +264,7 @@ github.com/google/go-cmp v0.3.1 h1:Xye71clBPdm5HgqGwUkwhbynsUJZhDbS20FvLhQ2izg=
 github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/go-cmp v0.4.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.4.1/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.2 h1:X2ev0eStA3AbceY54o37/0PQ/UWqKEiiO2dKL5OPaFM=
 github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.3 h1:x95R7cp+rSeeqAMI2knLtQ0DKlaBhv2NrtrOvafPHRo=
@@ -839,6 +842,8 @@ google.golang.org/protobuf v1.23.0/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2
 google.golang.org/protobuf v1.23.1-0.20200526195155-81db48ad09cc/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2l/sGQquU=
 google.golang.org/protobuf v1.24.0 h1:UhZDfRO8JRQru4/+LlLE0BRKGF8L+PICnvYZmx/fEGA=
 google.golang.org/protobuf v1.24.0/go.mod h1:r/3tXBNzIEhYS9I1OUVjXDlt8tc493IdKGjtUeSXeh4=
+google.golang.org/protobuf v1.25.0 h1:Ejskq+SyPohKW+1uil0JJMtmHCgJPJ/qWTxr8qp+R4c=
+google.golang.org/protobuf v1.25.0/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlbajtzgsN7c=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=

hugolib/hugo_sites_build.go

@@ -48,6 +48,11 @@ func (h *HugoSites) Build(config BuildCfg, events ...fsnotify.Event) error {
 		// Make sure we don't trigger rebuilds in parallel.
 		h.runningMu.Lock()
 		defer h.runningMu.Unlock()
+	} else {
+		defer func() {
+			// TODO1 server close
+			h.Deps.BuildClosers.Close()
+		}()
 	}
 
 	ctx, task := trace.NewTask(context.Background(), "Build")