src/jdk.jextract/share/classes/com/sun/tools/jextract/JextractTool.java

@@ -57,10 +57,11 @@
     public Writer processHeaders() {
         Map<HeaderFile, List<Tree>> headerMap = parser.parse(sources, clangArgs).stream()
                 .map(symbolFilter)
                 .map(new TypedefHandler())
                 .map(new EmptyNameHandler())
+                .map(new DuplicateDeclarationHandler())
                 .flatMap(h -> h.declarations().stream())
                 .distinct()
                 .collect(Collectors.groupingBy(this::headerFromDecl));
 
         //generate classes