postcss: Fix import error handling

Note that we will now fail if `inlineImports` is enabled and we cannot resolve an import.

You can work around this by either:

* Use url imports or imports with media queries.
* Set `skipInlineImportsNotFound=true` in the options

Also get the argument order in the different NewFileError* funcs in line.

Fixes #9895

3 files changed, 84 insertions, 15 deletions

diff --git a/resources/resource_transformers/postcss/integration_test.go b/resources/resource_transformers/postcss/integration_test.go
index 4101818be..69f0964d0 100644
--- a/resources/resource_transformers/postcss/integration_test.go
+++ b/resources/resource_transformers/postcss/integration_test.go
@@ -48,7 +48,7 @@ class-in-b {
 @tailwind base;
 @tailwind components;
 @tailwind utilities;
-@import "components/all.css";
+  @import "components/all.css";
 h1 {
 	@apply text-2xl font-bold;
 }
@@ -140,3 +140,49 @@ func TestTransformPostCSSError(t *testing.T) {
 	c.Assert(err.Error(), qt.Contains, "a.css:4:2")
 
 }
+
+// #9895
+func TestTransformPostCSSImportError(t *testing.T) {
+	if !htesting.IsCI() {
+		t.Skip("Skip long running test when running locally")
+	}
+
+	c := qt.New(t)
+
+	s, err := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:               c,
+			NeedsOsFS:       true,
+			NeedsNpmInstall: true,
+			LogLevel:        jww.LevelInfo,
+			TxtarString:     strings.ReplaceAll(postCSSIntegrationTestFiles, `@import "components/all.css";`, `@import "components/doesnotexist.css";`),
+		}).BuildE()
+
+	s.AssertIsFileError(err)
+	c.Assert(err.Error(), qt.Contains, "styles.css:4:3")
+	c.Assert(err.Error(), qt.Contains, filepath.FromSlash(`failed to resolve CSS @import "css/components/doesnotexist.css"`))
+
+}
+
+func TestTransformPostCSSImporSkipInlineImportsNotFound(t *testing.T) {
+	if !htesting.IsCI() {
+		t.Skip("Skip long running test when running locally")
+	}
+
+	c := qt.New(t)
+
+	files := strings.ReplaceAll(postCSSIntegrationTestFiles, `@import "components/all.css";`, `@import "components/doesnotexist.css";`)
+	files = strings.ReplaceAll(files, `{{ $options := dict "inlineImports" true }}`, `{{ $options := dict "inlineImports" true "skipInlineImportsNotFound" true }}`)
+
+	s := hugolib.NewIntegrationTestBuilder(
+		hugolib.IntegrationTestConfig{
+			T:               c,
+			NeedsOsFS:       true,
+			NeedsNpmInstall: true,
+			LogLevel:        jww.LevelInfo,
+			TxtarString:     files,
+		}).Build()
+
+	s.AssertFileContent("public/css/styles.css", filepath.FromSlash(`@import "components/doesnotexist.css";`))
+
+}
diff --git a/resources/resource_transformers/postcss/postcss.go b/resources/resource_transformers/postcss/postcss.go
index a5c86df6f..325dc1ec2 100644
--- a/resources/resource_transformers/postcss/postcss.go
+++ b/resources/resource_transformers/postcss/postcss.go
@@ -28,6 +28,7 @@ import (
 
 	"github.com/gohugoio/hugo/common/collections"
 	"github.com/gohugoio/hugo/common/hexec"
+	"github.com/gohugoio/hugo/common/text"
 	"github.com/gohugoio/hugo/hugofs"
 
 	"github.com/gohugoio/hugo/common/hugo"
@@ -49,9 +50,10 @@ import (
 
 const importIdentifier = "@import"
 
-var cssSyntaxErrorRe = regexp.MustCompile(`> (\d+) \|`)
-
-var shouldImportRe = regexp.MustCompile(`^@import ["'].*["'];?\s*(/\*.*\*/)?$`)
+var (
+	cssSyntaxErrorRe = regexp.MustCompile(`> (\d+) \|`)
+	shouldImportRe   = regexp.MustCompile(`^@import ["'].*["'];?\s*(/\*.*\*/)?$`)
+)
 
 // New creates a new Client with the given specification.
 func New(rs *resources.Spec) *Client {
@@ -100,6 +102,12 @@ type Options struct {
 	// so you can have @import anywhere in the file.
 	InlineImports bool
 
+	// When InlineImports is enabled, we fail the build if an import cannot be resolved.
+	// You can enable this to allow the build to continue and leave the import statement in place.
+	// Note that the inline importer does not process url location or imports with media queries,
+	// so those will be left as-is even without enabling this option.
+	SkipInlineImportsNotFound bool
+
 	// Options for when not using a config file
 	Use         string // List of postcss plugins to use
 	Parser      string //  Custom postcss parser
@@ -204,6 +212,7 @@ func (t *postcssTransformation) Transform(ctx *resources.ResourceTransformationC
 	imp := newImportResolver(
 		ctx.From,
 		ctx.InPath,
+		t.options,
 		t.rs.Assets.Fs, t.rs.Logger,
 	)
 
@@ -239,6 +248,7 @@ type fileOffset struct {
 type importResolver struct {
 	r      io.Reader
 	inPath string
+	opts   Options
 
 	contentSeen map[string]bool
 	linemap     map[int]fileOffset
@@ -246,12 +256,13 @@ type importResolver struct {
 	logger      loggers.Logger
 }
 
-func newImportResolver(r io.Reader, inPath string, fs afero.Fs, logger loggers.Logger) *importResolver {
+func newImportResolver(r io.Reader, inPath string, opts Options, fs afero.Fs, logger loggers.Logger) *importResolver {
 	return &importResolver{
 		r:      r,
 		inPath: inPath,
 		fs:     fs, logger: logger,
 		linemap: make(map[int]fileOffset), contentSeen: make(map[string]bool),
+		opts: opts,
 	}
 }
 
@@ -282,21 +293,32 @@ func (imp *importResolver) importRecursive(
 	i := 0
 	for offset, line := range lines {
 		i++
-		line = strings.TrimSpace(line)
+		lineTrimmed := strings.TrimSpace(line)
+		column := strings.Index(line, lineTrimmed)
+		line = lineTrimmed
 
 		if !imp.shouldImport(line) {
 			trackLine(i, offset, line)
 		} else {
-			i--
 			path := strings.Trim(strings.TrimPrefix(line, importIdentifier), " \"';")
 			filename := filepath.Join(basePath, path)
 			importContent, hash := imp.contentHash(filename)
+
 			if importContent == nil {
-				trackLine(i, offset, "ERROR")
-				imp.logger.Warnf("postcss: Failed to resolve CSS @import in %q for path %q", inPath, filename)
-				continue
+				if imp.opts.SkipInlineImportsNotFound {
+					trackLine(i, offset, line)
+					continue
+				}
+				pos := text.Position{
+					Filename:     inPath,
+					LineNumber:   offset + 1,
+					ColumnNumber: column + 1,
+				}
+				return 0, "", herrors.NewFileErrorFromFileInPos(fmt.Errorf("failed to resolve CSS @import %q", filename), pos, imp.fs, nil)
 			}
 
+			i--
+
 			if imp.contentSeen[hash] {
 				i++
 				// Just replace the line with an empty string.
@@ -399,7 +421,7 @@ func (imp *importResolver) toFileError(output string) error {
 	}
 	defer f.Close()
 
-	ferr := herrors.NewFileError(realFilename, inErr)
+	ferr := herrors.NewFileError(inErr, realFilename)
 	pos := ferr.Position()
 	pos.LineNumber = file.Offset + 1
 	return ferr.UpdatePosition(pos).UpdateContent(f, nil)
diff --git a/resources/resource_transformers/postcss/postcss_test.go b/resources/resource_transformers/postcss/postcss_test.go
index 4548bca98..f5d49300a 100644
--- a/resources/resource_transformers/postcss/postcss_test.go
+++ b/resources/resource_transformers/postcss/postcss_test.go
@@ -60,6 +60,7 @@ func TestShouldImport(t *testing.T) {
 		{input: `@import 'navigation.css';`, expect: true},
 		{input: `@import url("navigation.css");`, expect: false},
 		{input: `@import url('https://fonts.googleapis.com/css?family=Open+Sans:400,400i,800,800i&display=swap');`, expect: false},
+		{input: `@import "printstyle.css" print;`, expect: false},
 	} {
 		c.Assert(imp.shouldImport(test.input), qt.Equals, test.expect)
 	}
@@ -88,12 +89,12 @@ A_STYLE2
 @import "b.css";
 LOCAL_STYLE
 @import "c.css";
-@import "e.css";
-@import "missing.css";`)
+@import "e.css";`)
 
 	imp := newImportResolver(
 		mainStyles,
 		"styles.css",
+		Options{},
 		fs, loggers.NewErrorLogger(),
 	)
 
@@ -108,8 +109,7 @@ C_STYLE
 A_STYLE1
 A_STYLE2
 LOCAL_STYLE
-E_STYLE
-@import "missing.css";`)
+E_STYLE`)
 
 	dline := imp.linemap[3]
 	c.Assert(dline, qt.DeepEquals, fileOffset{
@@ -151,6 +151,7 @@ LOCAL_STYLE
 		imp := newImportResolver(
 			strings.NewReader(mainStyles),
 			"styles.css",
+			Options{},
 			fs, logger,
 		)