diff --git a/.gitignore b/.gitignore
index 6f6b8c23..52681010 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,6 +10,7 @@
 *.DS_Store
 
 _temp/
+*.log
 
 # Test binary, built with `go test -c`
 *.test
diff --git a/clang/clang.go b/clang/clang.go
index 674017ff..e10e6c2f 100644
--- a/clang/clang.go
+++ b/clang/clang.go
@@ -31,7 +31,9 @@ type stringer interface {
 
 // String returns the Go string of a value whose String() returns a clang String.
 func String[T stringer](v T) string {
-	return clang.GoString(v.String())
+	str := v.String()
+	defer str.Dispose()
+	return c.GoString(str.CStr())
 }
 
 // -----------------------------------------------------------------------------
@@ -112,6 +114,11 @@ func (u TranslationUnit) Cursor() Cursor {
 	return u.impl.Cursor()
 }
 
+// Underlying returns the underlying clang TranslationUnit.
+func (u TranslationUnit) Underlying() *clang.TranslationUnit {
+	return u.impl
+}
+
 // -----------------------------------------------------------------------------
 
 /**
@@ -134,6 +141,21 @@ func (u TranslationUnit) Cursor() Cursor {
  */
 type Cursor = clang.Cursor
 
+/**
+ * Identifies a specific source location within a translation
+ * unit.
+ *
+ * Use clang_getExpansionLocation() or clang_getSpellingLocation()
+ * to map a source location to a particular file, line, and column.
+ */
+type SourceLocation = clang.SourceLocation
+
+// PresumedFile returns the presumed file name for the given source location.
+func PresumedFile(loc SourceLocation) (filename clang.String) {
+	loc.PresumedLocation(&filename, nil, nil)
+	return
+}
+
 /**
  * Describes how the traversal of the children of a particular
  * cursor should proceed after visiting a particular child cursor.
diff --git a/cmd/llcppdump/cppdump.go b/cmd/llcppdump/cppdump.go
index 4ee725b1..6aed0aa1 100644
--- a/cmd/llcppdump/cppdump.go
+++ b/cmd/llcppdump/cppdump.go
@@ -22,18 +22,33 @@ import (
 	"os"
 	"strings"
 
+	"github.com/goplus/lib/c"
 	"github.com/goplus/llcppg/clang"
 	lc "github.com/goplus/llcppg/lib/clang"
 )
 
-func dump(c clang.Cursor, ns string) {
-	clang.VisitChildren(c, func(cur, parent clang.Cursor) clang.ChildVisitResult {
+func dump(node clang.Cursor, ns string, presumedFile *c.Char) {
+	clang.VisitChildren(node, func(cur, parent clang.Cursor) clang.ChildVisitResult {
+		if presumedFile != nil {
+			loc := cur.Location()
+			at := clang.PresumedFile(loc)
+			cmpf := c.Strcmp(at.CStr(), presumedFile)
+			at.Dispose()
+			if cmpf != 0 {
+				return clang.Continue
+			}
+		}
+		kind := cur.Kind
+		if kind == lc.CursorCXXAccessSpecifier {
+			log.Println("==>", kind, "CXXAccessSpecifier", cur.CXXAccessSpecifier())
+			return clang.Continue
+		}
 		name := ns + clang.String(cur)
-		log.Println("==>", cur.Kind, clang.String(cur.Kind), name)
-		switch cur.Kind {
+		log.Println("==>", kind, clang.String(kind), name)
+		switch kind {
 		case lc.CursorFunctionDecl, lc.CursorCXXMethod, lc.CursorConstructor, lc.CursorDestructor:
-		case lc.CursorNamespace:
-			dump(cur, name+"::")
+		case lc.CursorClassDecl, lc.CursorNamespace:
+			dump(cur, name+"::", presumedFile)
 		}
 		return clang.Continue
 	})
@@ -57,5 +72,17 @@ func main() {
 	u := idx.ParseTranslationUnit(0, filename, "-x", lang)
 	defer u.Dispose()
 
-	dump(u.Cursor(), "")
+	usys := u.Underlying()
+	spelling := usys.Spelling()
+	defer spelling.Dispose()
+	log.Println("==> TranslationUnit", c.GoString(spelling.CStr()))
+
+	file := usys.File(spelling.CStr())
+	loc := usys.GetLocationForOffset(file, 2)
+	presumedFile := clang.PresumedFile(loc)
+	defer presumedFile.Dispose()
+	log.Println("==> PresumedFile", c.GoString(presumedFile.CStr()))
+
+	root := u.Cursor()
+	dump(root, "", presumedFile.CStr())
 }
diff --git a/lib/clang/basic.go b/lib/clang/basic.go
index 0ddee092..272104cb 100644
--- a/lib/clang/basic.go
+++ b/lib/clang/basic.go
@@ -57,13 +57,3 @@ type StringSet struct {
  */
 // llgo:link (*StringSet).Dispose C.clang_disposeStringSet
 func (*StringSet) Dispose() {}
-
-// GoString returns the Go string representation of clangStr and disposes it.
-func GoString(clangStr String) (str string) {
-	defer clangStr.Dispose()
-	cstr := clangStr.CStr()
-	if cstr != nil {
-		str = c.GoString(cstr)
-	}
-	return
-}
diff --git a/lib/clang/clang.go b/lib/clang/clang.go
index d33a1707..50715d50 100644
--- a/lib/clang/clang.go
+++ b/lib/clang/clang.go
@@ -1284,7 +1284,7 @@ type TranslationUnit struct {
  * Destroy the specified CXTranslationUnit object.
  */
 // llgo:link (*TranslationUnit).Dispose C.clang_disposeTranslationUnit
-func (*TranslationUnit) Dispose() {}
+func (t *TranslationUnit) Dispose() {}
 
 /**
  * Retrieve the cursor that represents the given translation unit.
@@ -1297,6 +1297,16 @@ func (t *TranslationUnit) Cursor() (ret Cursor) {
 	return
 }
 
+// llgo:link (*TranslationUnit).File C.clang_getFile
+func (t *TranslationUnit) File(filename *c.Char) (ret File) {
+	return
+}
+
+// llgo:link (*TranslationUnit).Spelling C.clang_getTranslationUnitSpelling
+func (t *TranslationUnit) Spelling() (ret String) {
+	return
+}
+
 /**
  * Describes the kind of entity that a cursor refers to.
  */
@@ -1507,6 +1517,9 @@ type Type struct {
  */
 type File uintptr
 
+//llgo:link File.FileName C.clang_getFileName
+func (File) FileName() (ret String) { return }
+
 /**
  * Identifies a specific source location within a translation
  * unit.
@@ -2487,7 +2500,7 @@ func (c Token) Kind() (ret TokenKind) {
  * the text of an identifier or keyword.
  */
 // llgo:link (*TranslationUnit).Token C.clang_getTokenSpelling
-func (c *TranslationUnit) Token(token Token) (ret String) {
+func (t *TranslationUnit) Token(token Token) (ret String) {
 	return
 }
 
@@ -2634,26 +2647,6 @@ func (l SourceLocation) IsInSystemHeader() (ret c.Uint) {
 func (l SourceLocation) SpellingLocation(file *File, line, column, offset *c.Uint) {
 }
 
-func (l SourceLocation) File() (ret File) {
-	l.SpellingLocation(&ret, nil, nil, nil)
-	return
-}
-
-func (l SourceLocation) Line() (ret c.Uint) {
-	l.SpellingLocation(nil, &ret, nil, nil)
-	return
-}
-
-func (l SourceLocation) Column() (ret c.Uint) {
-	l.SpellingLocation(nil, nil, &ret, nil)
-	return
-}
-
-func (l SourceLocation) Offset() (ret c.Uint) {
-	l.SpellingLocation(nil, nil, nil, &ret)
-	return
-}
-
 /**
  * Retrieve the file, line and column represented by the given source
  * location, as specified in a # line directive.
@@ -2715,6 +2708,3 @@ func (r SourceRange) RangeStart() (loc SourceLocation) {
 func (r SourceRange) RangeEnd() (loc SourceLocation) {
 	return
 }
-
-//llgo:link File.FileName C.clang_getFileName
-func (File) FileName() (ret String) { return }