Fix #2538: Preserve original filename when using --front-matter

cmd/evaluate_all_command.go

@@ -101,12 +101,15 @@ func evaluateAll(cmd *cobra.Command, args []string) (cmdError error) {
 	}
 
 	if frontMatter != "" {
+		originalFilename := args[0]
 		frontMatterHandler := yqlib.NewFrontMatterHandler(args[0])
 		err = frontMatterHandler.Split()
 		if err != nil {
 			return err
 		}
 		args[0] = frontMatterHandler.GetYamlFrontMatterFilename()
+		yqlib.SetFilenameAlias(args[0], originalFilename)
+		defer yqlib.ClearFilenameAliases()
 
 		if frontMatter == "process" {
 			reader := frontMatterHandler.GetContentReader()

cmd/evaluate_sequence_command.go

@@ -122,12 +122,15 @@ func evaluateSequence(cmd *cobra.Command, args []string) (cmdError error) {
 
 	if frontMatter != "" {
 		yqlib.GetLogger().Debug("using front matter handler")
+		originalFilename := args[0]
 		frontMatterHandler := yqlib.NewFrontMatterHandler(args[0])
 		err = frontMatterHandler.Split()
 		if err != nil {
 			return err
 		}
 		args[0] = frontMatterHandler.GetYamlFrontMatterFilename()
+		yqlib.SetFilenameAlias(args[0], originalFilename)
+		defer yqlib.ClearFilenameAliases()
 
 		if frontMatter == "process" {
 			reader := frontMatterHandler.GetContentReader()

pkg/yqlib/front_matter_test.go

@@ -108,6 +108,55 @@ yaml: doc
 	fmHandler.CleanUp()
 }
 
+func TestFrontMatterFilenamePreserved(t *testing.T) {
+	// Regression test for https://github.com/mikefarah/yq/issues/2538
+	// When using --front-matter, the filename operator should return
+	// the original filename, not the path to the temporary file.
+	file := createTestFile(`---
+name: john
+---
+Some content
+`)
+	originalFilename := "/path/to/original/file.md"
+
+	fmHandler := NewFrontMatterHandler(file)
+	err := fmHandler.Split()
+	if err != nil {
+		panic(err)
+	}
+
+	tempFilename := fmHandler.GetYamlFrontMatterFilename()
+
+	// Register the alias (as the command code does)
+	SetFilenameAlias(tempFilename, originalFilename)
+	defer ClearFilenameAliases()
+
+	// Verify resolveFilename returns the original name
+	resolved := resolveFilename(tempFilename)
+	test.AssertResult(t, originalFilename, resolved)
+
+	// Read documents using the temp file, verify they get the original filename
+	reader, err := readStream(tempFilename)
+	if err != nil {
+		panic(err)
+	}
+	decoder := NewYamlDecoder(ConfiguredYamlPreferences)
+	docs, err := readDocuments(reader, tempFilename, 0, decoder)
+	if err != nil {
+		panic(err)
+	}
+
+	if docs.Len() == 0 {
+		t.Fatal("expected at least one document")
+	}
+
+	firstDoc := docs.Front().Value.(*CandidateNode)
+	test.AssertResult(t, originalFilename, firstDoc.filename)
+
+	tryRemoveTempFile(file)
+	fmHandler.CleanUp()
+}
+
 func TestFrontMatterSplitWithArray(t *testing.T) {
 	file := createTestFile(`[1,2,3]
 ---

pkg/yqlib/stream_evaluator.go

@@ -76,6 +76,7 @@ func (s *streamEvaluator) EvaluateFiles(expression string, filenames []string, p
 }
 
 func (s *streamEvaluator) Evaluate(filename string, reader io.Reader, node *ExpressionNode, printer Printer, decoder Decoder) (uint, error) {
+	filename = resolveFilename(filename)
 
 	var currentIndex uint
 	err := decoder.Init(reader)

pkg/yqlib/utils.go

@@ -9,6 +9,29 @@ import (
 	"os"
 )
 
+// filenameAliases maps real file paths to display names.
+// Used by front matter handling to preserve original filenames
+// when the actual content is read from temporary files.
+var filenameAliases = map[string]string{}
+
+// SetFilenameAlias registers a display name for a file path so that
+// the filename operator returns the original name instead of a temp path.
+func SetFilenameAlias(realPath string, displayName string) {
+	filenameAliases[realPath] = displayName
+}
+
+// ClearFilenameAliases removes all filename aliases.
+func ClearFilenameAliases() {
+	filenameAliases = map[string]string{}
+}
+
+func resolveFilename(filename string) string {
+	if alias, ok := filenameAliases[filename]; ok {
+		return alias
+	}
+	return filename
+}
+
 func readStream(filename string) (io.Reader, error) {
 	var reader *bufio.Reader
 	if filename == "-" {
@@ -36,6 +59,7 @@ func ReadDocuments(reader io.Reader, decoder Decoder) (*list.List, error) {
 }
 
 func readDocuments(reader io.Reader, filename string, fileIndex int, decoder Decoder) (*list.List, error) {
+	filename = resolveFilename(filename)
 	err := decoder.Init(reader)
 	if err != nil {
 		return nil, err