For the following header:

    typedef int MyInt;

    extern const int x;
    extern const MyInt x;

Extracting results in errors like:

    java.lang.RuntimeException: In memory compilation failed: warning: using incubating module(s): jdk.incubator.foreign
    org/jextract/test_h.java:29: error: method x$LAYOUT() is already defined in class test_h
        public static MemoryLayout x$LAYOUT() {
                                                     ^

Note that if chaning MyInt to int for the second declaration makes it work.