If a header file contains _Atomic types, for example, given the following,

typedef unsigned long ulong_t;
struct SomeTypes {
    _Atomic ulong_t aul;
    volatile unsigned int vui;
};

The _Atomic type will cause StackOverflowError as following stack trace.

The cause is that _Atomic types are unexposed in libclang, and the canonicalType give back the same type, thus cause an infinite recursion.

Exception in thread "main" java.lang.StackOverflowError
at java.base/java.nio.ByteBuffer.limit(ByteBuffer.java:1313)
at java.base/java.nio.MappedByteBuffer.limit(MappedByteBuffer.java:235)
at java.base/java.nio.MappedByteBuffer.limit(MappedByteBuffer.java:67)
at java.base/java.nio.Buffer.<init>(Buffer.java:223)
at java.base/java.nio.ByteBuffer.<init>(ByteBuffer.java:284)
at java.base/java.nio.ByteBuffer.<init>(ByteBuffer.java:292)
at java.base/java.nio.MappedByteBuffer.<init>(MappedByteBuffer.java:90)
at java.base/java.nio.DirectByteBuffer.<init>(DirectByteBuffer.java:115)
at java.base/java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:320)
at jdk.internal.clang/jdk.internal.clang.StructType.<init>(StructType.java:37)
at jdk.internal.clang/jdk.internal.clang.StructType.<init>(StructType.java:32)
at jdk.internal.clang/jdk.internal.clang.Type.<init>(Type.java:30)
at jdk.internal.clang/jdk.internal.clang.Type.canonicalType(Native Method)
at jdk.jextract/com.sun.tools.jextract.TypeDictionary.getInternal(TypeDictionary.java:146)
at jdk.jextract/com.sun.tools.jextract.TypeDictionary.getInternal(TypeDictionary.java:146)
at jdk.jextract/com.sun.tools.jextract.TypeDictionary.getInternal(TypeDictionary.java:146)
at jdk.jextract/com.sun.tools.jextract.TypeDictionary.getInternal(TypeDictionary.java:146)