Improve SASS errors

Fixes #9897

commands/server.go

@@ -482,6 +482,7 @@ func removeErrorPrefixFromLog(content string) string {
 var logReplacer = strings.NewReplacer(
 	"can't", "can’t", // Chroma lexer does'nt do well with "can't"
 	"*hugolib.pageState", "page.Page", // Page is the public interface.
+	"Rebuild failed:", "",
 )
 
 func cleanErrorLog(content string) string {

common/herrors/error_locator.go

@@ -52,6 +52,16 @@ var NopLineMatcher = func(m LineMatcher) int {
 	return 1
 }
 
+// OffsetMatcher is a line matcher that matches by offset.
+var OffsetMatcher = func(m LineMatcher) int {
+	if m.Offset+len(m.Line) >= m.Position.Offset {
+		// We found the line, but return 0 to signal that we want to determine
+		// the column from the error.
+		return 0
+	}
+	return -1
+}
+
 // ErrorContext contains contextual information about an error. This will
 // typically be the lines surrounding some problem in a file.
 type ErrorContext struct {

common/herrors/file_error.go

@@ -19,6 +19,8 @@ import (
 	"io"
 	"path/filepath"
 
+	"github.com/bep/godartsass"
+	"github.com/bep/golibsass/libsass/libsasserrors"
 	"github.com/gohugoio/hugo/common/paths"
 	"github.com/gohugoio/hugo/common/text"
 	"github.com/pelletier/go-toml/v2"
@@ -132,7 +134,22 @@ func (e fileError) Position() text.Position {
 }
 
 func (e *fileError) Error() string {
-	return fmt.Sprintf("%s: %s", e.position, e.cause)
+	return fmt.Sprintf("%s: %s", e.position, e.causeString())
+}
+
+func (e *fileError) causeString() string {
+	if e.cause == nil {
+		return ""
+	}
+	switch v := e.cause.(type) {
+	// Avoid repeating the file info in the error message.
+	case godartsass.SassError:
+		return v.Message
+	case libsasserrors.Error:
+		return v.Message
+	default:
+		return v.Error()
+	}
 }
 
 func (e *fileError) Unwrap() error {
@@ -140,9 +157,17 @@ func (e *fileError) Unwrap() error {
 }
 
 // NewFileError creates a new FileError that wraps err.
+// It will try to extract the filename and line number from err.
+func NewFileError(err error) FileError {
+	// Filetype is used to determine the Chroma lexer to use.
+	fileType, pos := extractFileTypePos(err)
+	return &fileError{cause: err, fileType: fileType, position: pos}
+}
+
+// NewFileErrorFromName creates a new FileError that wraps err.
 // The value for name should identify the file, the best
 // being the full filename to the file on disk.
-func NewFileError(err error, name string) FileError {
+func NewFileErrorFromName(err error, name string) FileError {
 	// Filetype is used to determine the Chroma lexer to use.
 	fileType, pos := extractFileTypePos(err)
 	pos.Filename = name
@@ -165,6 +190,23 @@ func NewFileErrorFromPos(err error, pos text.Position) FileError {
 
 }
 
+func NewFileErrorFromFileInErr(err error, fs afero.Fs, linematcher LineMatcherFn) FileError {
+	fe := NewFileError(err)
+	pos := fe.Position()
+	if pos.Filename == "" {
+		return fe
+	}
+
+	f, realFilename, err2 := openFile(pos.Filename, fs)
+	if err2 != nil {
+		return fe
+	}
+
+	pos.Filename = realFilename
+	defer f.Close()
+	return fe.UpdateContent(f, linematcher)
+}
+
 func NewFileErrorFromFileInPos(err error, pos text.Position, fs afero.Fs, linematcher LineMatcherFn) FileError {
 	if err == nil {
 		panic("err is nil")
@@ -185,10 +227,10 @@ func NewFileErrorFromFile(err error, filename string, fs afero.Fs, linematcher L
 	}
 	f, realFilename, err2 := openFile(filename, fs)
 	if err2 != nil {
-		return NewFileError(err, realFilename)
+		return NewFileErrorFromName(err, realFilename)
 	}
 	defer f.Close()
-	return NewFileError(err, realFilename).UpdateContent(f, linematcher)
+	return NewFileErrorFromName(err, realFilename).UpdateContent(f, linematcher)
 }
 
 func openFile(filename string, fs afero.Fs) (afero.File, string, error) {
@@ -223,8 +265,15 @@ func Cause(err error) error {
 
 func extractFileTypePos(err error) (string, text.Position) {
 	err = Cause(err)
+
 	var fileType string
 
+	// LibSass, DartSass
+	if pos := extractPosition(err); pos.LineNumber > 0 || pos.Offset > 0 {
+		_, fileType = paths.FileAndExtNoDelimiter(pos.Filename)
+		return fileType, pos
+	}
+
 	// Default to line 1 col 1 if we don't find any better.
 	pos := text.Position{
 		Offset:       -1,
@@ -259,6 +308,10 @@ func extractFileTypePos(err error) (string, text.Position) {
 		}
 	}
 
+	if fileType == "" && pos.Filename != "" {
+		_, fileType = paths.FileAndExtNoDelimiter(pos.Filename)
+	}
+
 	return fileType, pos
 }
 
@@ -322,3 +375,20 @@ func exctractLineNumberAndColumnNumber(e error) (int, int) {
 
 	return -1, -1
 }
+
+func extractPosition(e error) (pos text.Position) {
+	switch v := e.(type) {
+	case godartsass.SassError:
+		span := v.Span
+		start := span.Start
+		filename, _ := paths.UrlToFilename(span.Url)
+		pos.Filename = filename
+		pos.Offset = start.Offset
+		pos.ColumnNumber = start.Column
+	case libsasserrors.Error:
+		pos.Filename = v.File
+		pos.LineNumber = v.Line
+		pos.ColumnNumber = v.Column
+	}
+	return
+}

common/herrors/file_error_test.go

@@ -30,7 +30,7 @@ func TestNewFileError(t *testing.T) {
 
 	c := qt.New(t)
 
-	fe := NewFileError(errors.New("bar"), "foo.html")
+	fe := NewFileErrorFromName(errors.New("bar"), "foo.html")
 	c.Assert(fe.Error(), qt.Equals, `"foo.html:1:1": bar`)
 
 	lines := ""
@@ -70,7 +70,7 @@ func TestNewFileErrorExtractFromMessage(t *testing.T) {
 		{errors.New(`execute of template failed: template: index.html:2:5: executing "index.html" at <partial "foo.html" .>: error calling partial: "/layouts/partials/foo.html:3:6": execute of template failed: template: partials/foo.html:3:6: executing "partials/foo.html" at <.ThisDoesNotExist>: can't evaluate field ThisDoesNotExist in type *hugolib.pageStat`), 0, 2, 5},
 	} {
 
-		got := NewFileError(test.in, "test.txt")
+		got := NewFileErrorFromName(test.in, "test.txt")
 
 		errMsg := qt.Commentf("[%d][%T]", i, got)
 

common/paths/url.go

@@ -17,6 +17,7 @@ import (
 	"fmt"
 	"net/url"
 	"path"
+	"path/filepath"
 	"strings"
 )
 
@@ -152,3 +153,29 @@ func Uglify(in string) string {
 	// /section/name.html -> /section/name.html
 	return path.Clean(in)
 }
+
+// UrlToFilename converts the URL s to a filename.
+// If ParseRequestURI fails, the input is just converted to OS specific slashes and returned.
+func UrlToFilename(s string) (string, bool) {
+	u, err := url.ParseRequestURI(s)
+
+	if err != nil {
+		return filepath.FromSlash(s), false
+	}
+
+	p := u.Path
+
+	if p == "" {
+		p, _ = url.QueryUnescape(u.Opaque)
+		return filepath.FromSlash(p), true
+	}
+
+	p = filepath.FromSlash(p)
+
+	if u.Host != "" {
+		// C:\data\file.txt
+		p = strings.ToUpper(u.Host) + ":" + p
+	}
+
+	return p, true
+}

go.mod

@@ -11,7 +11,7 @@ require (
 	github.com/bep/gitmap v1.1.2
 	github.com/bep/goat v0.5.0
 	github.com/bep/godartsass v0.14.0
-	github.com/bep/golibsass v1.0.0
+	github.com/bep/golibsass v1.1.0
 	github.com/bep/gowebp v0.1.0
 	github.com/bep/overlayfs v0.6.0
 	github.com/bep/tmc v0.5.1

go.sum

@@ -175,6 +175,8 @@ github.com/bep/godartsass v0.14.0 h1:pPb6XkpyDEppS+wK0veh7OXDQc4xzOJI9Qcjb743UeQ
 github.com/bep/godartsass v0.14.0/go.mod h1:6LvK9RftsXMxGfsA0LDV12AGc4Jylnu6NgHL+Q5/pE8=
 github.com/bep/golibsass v1.0.0 h1:gNguBMSDi5yZEZzVZP70YpuFQE3qogJIGUlrVILTmOw=
 github.com/bep/golibsass v1.0.0/go.mod h1:DL87K8Un/+pWUS75ggYv41bliGiolxzDKWJAq3eJ1MA=
+github.com/bep/golibsass v1.1.0 h1:pjtXr00IJZZaOdfryNa9wARTB3Q0BmxC3/V1KNcgyTw=
+github.com/bep/golibsass v1.1.0/go.mod h1:DL87K8Un/+pWUS75ggYv41bliGiolxzDKWJAq3eJ1MA=
 github.com/bep/gowebp v0.1.0 h1:4/iQpfnxHyXs3x/aTxMMdOpLEQQhFmF6G7EieWPTQyo=
 github.com/bep/gowebp v0.1.0/go.mod h1:ZhFodwdiFp8ehGJpF4LdPl6unxZm9lLFjxD3z2h2AgI=
 github.com/bep/overlayfs v0.6.0 h1:sgLcq/qtIzbaQNl2TldGXOkHvqeZB025sPvHOQL+DYo=

hugolib/integrationtest_builder.go

@@ -168,8 +168,9 @@ func (s *IntegrationTestBuilder) destinationExists(filename string) bool {
 	return b
 }
 
-func (s *IntegrationTestBuilder) AssertIsFileError(err error) {
+func (s *IntegrationTestBuilder) AssertIsFileError(err error) herrors.FileError {
 	s.Assert(err, qt.ErrorAs, new(herrors.FileError))
+	return herrors.UnwrapFileError(err)
 }
 
 func (s *IntegrationTestBuilder) AssertRenderCountContent(count int) {

hugolib/page.go

@@ -788,7 +788,7 @@ func (p *pageState) outputFormat() (f output.Format) {
 
 func (p *pageState) parseError(err error, input []byte, offset int) error {
 	pos := p.posFromInput(input, offset)
-	return herrors.NewFileError(err, p.File().Filename()).UpdatePosition(pos)
+	return herrors.NewFileErrorFromName(err, p.File().Filename()).UpdatePosition(pos)
 }
 
 func (p *pageState) pathOrTitle() string {

hugolib/shortcode.go

@@ -298,7 +298,7 @@ func renderShortcode(
 			var err error
 			tmpl, err = s.TextTmpl().Parse(templName, templStr)
 			if err != nil {
-				fe := herrors.NewFileError(err, p.File().Filename())
+				fe := herrors.NewFileErrorFromName(err, p.File().Filename())
 				pos := fe.Position()
 				pos.LineNumber += p.posOffset(sc.pos).LineNumber
 				fe = fe.UpdatePosition(pos)
@@ -391,7 +391,7 @@ func renderShortcode(
 	result, err := renderShortcodeWithPage(s.Tmpl(), tmpl, data)
 
 	if err != nil && sc.isInline {
-		fe := herrors.NewFileError(err, p.File().Filename())
+		fe := herrors.NewFileErrorFromName(err, p.File().Filename())
 		pos := fe.Position()
 		pos.LineNumber += p.posOffset(sc.pos).LineNumber
 		fe = fe.UpdatePosition(pos)

langs/i18n/translationProvider.go

@@ -138,6 +138,6 @@ func errWithFileContext(inerr error, r source.File) error {
 	}
 	defer f.Close()
 
-	return herrors.NewFileError(inerr, realFilename).UpdateContent(f, nil)
+	return herrors.NewFileErrorFromName(inerr, realFilename).UpdateContent(f, nil)
 
 }

parser/metadecoders/decoder.go

@@ -260,7 +260,7 @@ func (d Decoder) unmarshalORG(data []byte, v any) error {
 }
 
 func toFileError(f Format, data []byte, err error) error {
-	return herrors.NewFileError(err, fmt.Sprintf("_stream.%s", f)).UpdateContent(bytes.NewReader(data), nil)
+	return herrors.NewFileErrorFromName(err, fmt.Sprintf("_stream.%s", f)).UpdateContent(bytes.NewReader(data), nil)
 }
 
 // stringifyMapKeys recurses into in and changes all instances of

resources/resource_transformers/js/build.go

@@ -165,7 +165,7 @@ func (t *buildTransformation) Transform(ctx *resources.ResourceTransformationCtx
 
 			if err == nil {
 				fe := herrors.
-					NewFileError(errors.New(errorMessage), path).
+					NewFileErrorFromName(errors.New(errorMessage), path).
 					UpdatePosition(text.Position{Offset: -1, LineNumber: loc.Line, ColumnNumber: loc.Column}).
 					UpdateContent(f, nil)
 

resources/resource_transformers/postcss/integration_test.go

@@ -183,6 +183,6 @@ func TestTransformPostCSSImporSkipInlineImportsNotFound(t *testing.T) {
 			TxtarString:     files,
 		}).Build()
 
-	s.AssertFileContent("public/css/styles.css", filepath.FromSlash(`@import "components/doesnotexist.css";`))
+	s.AssertFileContent("public/css/styles.css", `@import "components/doesnotexist.css";`)
 
 }

resources/resource_transformers/postcss/postcss.go

@@ -314,7 +314,7 @@ func (imp *importResolver) importRecursive(
 					LineNumber:   offset + 1,
 					ColumnNumber: column + 1,
 				}
-				return 0, "", herrors.NewFileErrorFromFileInPos(fmt.Errorf("failed to resolve CSS @import %q", filename), pos, imp.fs, nil)
+				return 0, "", herrors.NewFileErrorFromFileInPos(fmt.Errorf("failed to resolve CSS @import \"%s\"", filename), pos, imp.fs, nil)
 			}
 
 			i--
@@ -421,7 +421,7 @@ func (imp *importResolver) toFileError(output string) error {
 	}
 	defer f.Close()
 
-	ferr := herrors.NewFileError(inErr, realFilename)
+	ferr := herrors.NewFileErrorFromName(inErr, realFilename)
 	pos := ferr.Position()
 	pos.LineNumber = file.Offset + 1
 	return ferr.UpdatePosition(pos).UpdateContent(f, nil)

resources/resource_transformers/tocss/dartsass/client.go

@@ -20,7 +20,9 @@ import (
 	"io"
 	"strings"
 
+	"github.com/gohugoio/hugo/common/herrors"
 	"github.com/gohugoio/hugo/helpers"
+	"github.com/gohugoio/hugo/hugofs"
 	"github.com/gohugoio/hugo/hugolib/filesystems"
 	"github.com/gohugoio/hugo/resources"
 	"github.com/gohugoio/hugo/resources/resource"
@@ -33,6 +35,10 @@ import (
 // used as part of the cache key.
 const transformationName = "tocss-dart"
 
+// See https://github.com/sass/dart-sass-embedded/issues/24
+// Note: This prefix must be all lower case.
+const dartSassStdinPrefix = "hugostdin:"
+
 func New(fs *filesystems.SourceFilesystem, rs *resources.Spec) (*Client, error) {
 	if !Supports() {
 		return &Client{dartSassNotAvailable: true}, nil
@@ -44,7 +50,7 @@ func New(fs *filesystems.SourceFilesystem, rs *resources.Spec) (*Client, error)
 
 	transpiler, err := godartsass.Start(godartsass.Options{
 		LogEventHandler: func(event godartsass.LogEvent) {
-			message := strings.ReplaceAll(event.Message, stdinPrefix, "")
+			message := strings.ReplaceAll(event.Message, dartSassStdinPrefix, "")
 			switch event.Type {
 			case godartsass.LogEventTypeDebug:
 				// Log as Info for now, we may adjust this if it gets too chatty.
@@ -94,7 +100,7 @@ func (c *Client) toCSS(args godartsass.Args, src io.Reader) (godartsass.Result,
 		if err.Error() == "unexpected EOF" {
 			return res, fmt.Errorf("got unexpected EOF when executing %q. The user running hugo must have read and execute permissions on this program. With execute permissions only, this error is thrown.", dartSassEmbeddedBinaryName)
 		}
-		return res, err
+		return res, herrors.NewFileErrorFromFileInErr(err, hugofs.Os, herrors.OffsetMatcher)
 	}
 
 	return res, err

resources/resource_transformers/tocss/dartsass/integration_test.go

@@ -14,8 +14,10 @@
 package dartsass_test
 
 import (
+	"strings"
 	"testing"
 
+	qt "github.com/frankban/quicktest"
 	"github.com/gohugoio/hugo/hugolib"
 	"github.com/gohugoio/hugo/resources/resource_transformers/tocss/dartsass"
 	jww "github.com/spf13/jwalterweatherman"
@@ -196,3 +198,76 @@ T1: {{ $r.Content }}
 	b.AssertLogMatches(`INFO.*Dart Sass: .*assets.*main.scss:1:0: bar`)
 
 }
+
+func TestTransformErrors(t *testing.T) {
+	if !dartsass.Supports() {
+		t.Skip()
+	}
+
+	c := qt.New(t)
+
+	const filesTemplate = `
+-- config.toml --
+-- assets/scss/components/_foo.scss --
+/* comment line 1 */
+$foocolor: #ccc;
+
+foo {
+	color: $foocolor;
+}
+-- assets/scss/main.scss --
+/* comment line 1 */
+/* comment line 2 */
+@import "components/foo";
+/* comment line 4 */
+
+  $maincolor: #eee;
+
+body {
+	color: $maincolor;
+}
+
+-- layouts/index.html --
+{{ $cssOpts := dict "transpiler" "dartsass" }}
+{{ $r := resources.Get "scss/main.scss" |  toCSS $cssOpts  | minify  }}
+T1: {{ $r.Content }}
+
+	`
+
+	c.Run("error in main", func(c *qt.C) {
+		b, err := hugolib.NewIntegrationTestBuilder(
+			hugolib.IntegrationTestConfig{
+				T:           c,
+				TxtarString: strings.Replace(filesTemplate, "$maincolor: #eee;", "$maincolor #eee;", 1),
+				NeedsOsFS:   true,
+			}).BuildE()
+
+		b.Assert(err, qt.IsNotNil)
+		b.Assert(err.Error(), qt.Contains, `main.scss:8:13":`)
+		b.Assert(err.Error(), qt.Contains, `: expected ":".`)
+		fe := b.AssertIsFileError(err)
+		b.Assert(fe.ErrorContext(), qt.IsNotNil)
+		b.Assert(fe.ErrorContext().Lines, qt.DeepEquals, []string{"  $maincolor #eee;", "", "body {", "\tcolor: $maincolor;", "}"})
+		b.Assert(fe.ErrorContext().ChromaLexer, qt.Equals, "scss")
+
+	})
+
+	c.Run("error in import", func(c *qt.C) {
+		b, err := hugolib.NewIntegrationTestBuilder(
+			hugolib.IntegrationTestConfig{
+				T:           c,
+				TxtarString: strings.Replace(filesTemplate, "$foocolor: #ccc;", "$foocolor #ccc;", 1),
+				NeedsOsFS:   true,
+			}).BuildE()
+
+		b.Assert(err, qt.IsNotNil)
+		b.Assert(err.Error(), qt.Contains, `_foo.scss:2:10":`)
+		b.Assert(err.Error(), qt.Contains, `: expected ":".`)
+		fe := b.AssertIsFileError(err)
+		b.Assert(fe.ErrorContext(), qt.IsNotNil)
+		b.Assert(fe.ErrorContext().Lines, qt.DeepEquals, []string{"/* comment line 1 */", "$foocolor #ccc;", "", "foo {"})
+		b.Assert(fe.ErrorContext().ChromaLexer, qt.Equals, "scss")
+
+	})
+
+}

resources/resource_transformers/tocss/dartsass/transform.go

@@ -16,13 +16,12 @@ package dartsass
 import (
 	"fmt"
 	"io"
-	"net/url"
 	"path"
 	"path/filepath"
 	"strings"
 
-	"github.com/gohugoio/hugo/common/herrors"
 	"github.com/gohugoio/hugo/common/hexec"
+	"github.com/gohugoio/hugo/common/paths"
 	"github.com/gohugoio/hugo/htesting"
 	"github.com/gohugoio/hugo/media"
 
@@ -38,9 +37,6 @@ import (
 )
 
 const (
-	// See https://github.com/sass/dart-sass-embedded/issues/24
-	// Note: This prefix must be all lower case.
-	stdinPrefix                = "hugostdin:"
 	dartSassEmbeddedBinaryName = "dart-sass-embedded"
 )
 
@@ -76,7 +72,7 @@ func (t *transform) Transform(ctx *resources.ResourceTransformationCtx) error {
 	}
 
 	baseDir := path.Dir(ctx.SourcePath)
-	filename := stdinPrefix
+	filename := dartSassStdinPrefix
 
 	if ctx.SourcePath != "" {
 		filename += t.c.sfs.RealFilename(ctx.SourcePath)
@@ -108,26 +104,6 @@ func (t *transform) Transform(ctx *resources.ResourceTransformationCtx) error {
 
 	res, err := t.c.toCSS(args, ctx.From)
 	if err != nil {
-		if sassErr, ok := err.(godartsass.SassError); ok {
-			start := sassErr.Span.Start
-			context := strings.TrimSpace(sassErr.Span.Context)
-			filename, _ := urlToFilename(sassErr.Span.Url)
-			if strings.HasPrefix(filename, stdinPrefix) {
-				filename = filename[len(stdinPrefix):]
-			}
-
-			offsetMatcher := func(m herrors.LineMatcher) int {
-				if m.Offset+len(m.Line) >= start.Offset && strings.Contains(m.Line, context) {
-					// We found the line, but return 0 to signal that we want to determine
-					// the column from the error.
-					return 0
-				}
-				return -1
-			}
-
-			return herrors.NewFileErrorFromFile(sassErr, filename, hugofs.Os, offsetMatcher)
-
-		}
 		return err
 	}
 
@@ -154,7 +130,7 @@ type importResolver struct {
 }
 
 func (t importResolver) CanonicalizeURL(url string) (string, error) {
-	filePath, isURL := urlToFilename(url)
+	filePath, isURL := paths.UrlToFilename(url)
 	var prevDir string
 	var pathDir string
 	if isURL {
@@ -200,23 +176,7 @@ func (t importResolver) CanonicalizeURL(url string) (string, error) {
 }
 
 func (t importResolver) Load(url string) (string, error) {
-	filename, _ := urlToFilename(url)
+	filename, _ := paths.UrlToFilename(url)
 	b, err := afero.ReadFile(hugofs.Os, filename)
 	return string(b), err
 }
-
-// TODO(bep) add tests
-func urlToFilename(urls string) (string, bool) {
-	u, err := url.ParseRequestURI(urls)
-	if err != nil {
-		return filepath.FromSlash(urls), false
-	}
-	p := filepath.FromSlash(u.Path)
-
-	if u.Host != "" {
-		// C:\data\file.txt
-		p = strings.ToUpper(u.Host) + ":" + p
-	}
-
-	return p, true
-}

resources/resource_transformers/tocss/scss/client_extended.go

@@ -47,6 +47,7 @@ func (c *Client) ToCSS(res resources.ResourceTransformer, opts Options) (resourc
 	}
 
 	return res.Transform(&toCSSTransformation{c: c, options: internalOptions})
+
 }
 
 type toCSSTransformation struct {

resources/resource_transformers/tocss/scss/integration_test.go

@@ -14,6 +14,8 @@
 package scss_test
 
 import (
+	"path/filepath"
+	"strings"
 	"testing"
 
 	qt "github.com/frankban/quicktest"
@@ -133,7 +135,7 @@ moo {
 -- config.toml --
 theme = 'mytheme'
 -- layouts/index.html --
-{{ $cssOpts := (dict "includePaths" (slice "node_modules/foo" ) "transpiler" "dartsass" ) }}
+{{ $cssOpts := (dict "includePaths" (slice "node_modules/foo" ) ) }}
 {{ $r := resources.Get "scss/main.scss" |  toCSS $cssOpts  | minify  }}
 T1: {{ $r.Content }}
 -- themes/mytheme/assets/scss/components/_boo.scss --
@@ -171,3 +173,75 @@ zoo {
 
 	b.AssertFileContent("public/index.html", `T1: moo{color:#ccc}boo{color:green}zoo{color:pink}`)
 }
+
+func TestTransformErrors(t *testing.T) {
+	if !scss.Supports() {
+		t.Skip()
+	}
+
+	c := qt.New(t)
+
+	const filesTemplate = `
+-- config.toml --
+theme = 'mytheme'
+-- assets/scss/components/_foo.scss --
+/* comment line 1 */
+$foocolor: #ccc;
+
+foo {
+	color: $foocolor;
+}
+-- themes/mytheme/assets/scss/main.scss --
+/* comment line 1 */
+/* comment line 2 */
+@import "components/foo";
+/* comment line 4 */
+
+$maincolor: #eee;
+
+body {
+	color: $maincolor;
+}
+
+-- layouts/index.html --
+{{ $cssOpts := dict }}
+{{ $r := resources.Get "scss/main.scss" |  toCSS $cssOpts  | minify  }}
+T1: {{ $r.Content }}
+
+	`
+
+	c.Run("error in main", func(c *qt.C) {
+		b, err := hugolib.NewIntegrationTestBuilder(
+			hugolib.IntegrationTestConfig{
+				T:           c,
+				TxtarString: strings.Replace(filesTemplate, "$maincolor: #eee;", "$maincolor #eee;", 1),
+				NeedsOsFS:   true,
+			}).BuildE()
+
+		b.Assert(err, qt.IsNotNil)
+		b.Assert(err.Error(), qt.Contains, filepath.FromSlash(`themes/mytheme/assets/scss/main.scss:6:1": expected ':' after $maincolor in assignment statement`))
+		fe := b.AssertIsFileError(err)
+		b.Assert(fe.ErrorContext(), qt.IsNotNil)
+		b.Assert(fe.ErrorContext().Lines, qt.DeepEquals, []string{"/* comment line 4 */", "", "$maincolor #eee;", "", "body {"})
+		b.Assert(fe.ErrorContext().ChromaLexer, qt.Equals, "scss")
+
+	})
+
+	c.Run("error in import", func(c *qt.C) {
+		b, err := hugolib.NewIntegrationTestBuilder(
+			hugolib.IntegrationTestConfig{
+				T:           c,
+				TxtarString: strings.Replace(filesTemplate, "$foocolor: #ccc;", "$foocolor #ccc;", 1),
+				NeedsOsFS:   true,
+			}).BuildE()
+
+		b.Assert(err, qt.IsNotNil)
+		b.Assert(err.Error(), qt.Contains, filepath.FromSlash(`assets/scss/components/_foo.scss:2:1": expected ':' after $foocolor in assignment statement`))
+		fe := b.AssertIsFileError(err)
+		b.Assert(fe.ErrorContext(), qt.IsNotNil)
+		b.Assert(fe.ErrorContext().Lines, qt.DeepEquals, []string{"/* comment line 1 */", "$foocolor #ccc;", "", "foo {"})
+		b.Assert(fe.ErrorContext().ChromaLexer, qt.Equals, "scss")
+
+	})
+
+}

resources/resource_transformers/tocss/scss/tocss.go

@@ -20,10 +20,13 @@ import (
 	"fmt"
 	"io"
 	"path"
+
 	"path/filepath"
 	"strings"
 
 	"github.com/bep/golibsass/libsass"
+	"github.com/bep/golibsass/libsass/libsasserrors"
+	"github.com/gohugoio/hugo/common/herrors"
 	"github.com/gohugoio/hugo/helpers"
 	"github.com/gohugoio/hugo/hugofs"
 	"github.com/gohugoio/hugo/media"
@@ -136,7 +139,14 @@ func (t *toCSSTransformation) Transform(ctx *resources.ResourceTransformationCtx
 
 	res, err := t.c.toCSS(options.to, ctx.To, ctx.From)
 	if err != nil {
-		return err
+		if sasserr, ok := err.(libsasserrors.Error); ok {
+			if sasserr.File == "stdin" && ctx.SourcePath != "" {
+				sasserr.File = t.c.sfs.RealFilename(ctx.SourcePath)
+				err = sasserr
+			}
+		}
+		return herrors.NewFileErrorFromFileInErr(err, hugofs.Os, nil)
+
 	}
 
 	if options.from.EnableSourceMap && res.SourceMapContent != "" {
@@ -180,7 +190,7 @@ func (c *Client) toCSS(options libsass.Options, dst io.Writer, src io.Reader) (l
 
 	res, err = transpiler.Execute(in)
 	if err != nil {
-		return res, fmt.Errorf("SCSS processing failed: %w", err)
+		return res, err
 	}
 
 	out := res.CSS

tpl/tplimpl/template.go

@@ -554,7 +554,7 @@ func (t *templateHandler) addFileContext(templ tpl.Template, inerr error) error
 		}
 		defer f.Close()
 
-		fe := herrors.NewFileError(inErr, info.realFilename)
+		fe := herrors.NewFileErrorFromName(inErr, info.realFilename)
 		fe.UpdateContent(f, lineMatcher)
 
 		if !fe.ErrorContext().Position.IsValid() {

tpl/tplimpl/template_errors.go

@@ -53,7 +53,7 @@ func (t templateInfo) resolveType() templateType {
 
 func (info templateInfo) errWithFileContext(what string, err error) error {
 	err = fmt.Errorf(what+": %w", err)
-	fe := herrors.NewFileError(err, info.realFilename)
+	fe := herrors.NewFileErrorFromName(err, info.realFilename)
 	f, err := info.fs.Open(info.filename)
 	if err != nil {
 		return err

transform/chain.go

@@ -115,7 +115,7 @@ func (c *Chain) Apply(to io.Writer, from io.Reader) error {
 				_, _ = io.Copy(tempfile, fb.from)
 				return herrors.NewFileErrorFromFile(err, filename, hugofs.Os, nil)
 			}
-			return herrors.NewFileError(err, filename).UpdateContent(fb.from, nil)
+			return herrors.NewFileErrorFromName(err, filename).UpdateContent(fb.from, nil)
 
 		}
 	}