Jextract parses macros using javac support for constant folding. While this is an effective approach, it has limitations in terms of which macros can be supported. For instance, such an approach cannot scale to constants such as these:

#define PTR (void*)0;

Because javac doesn't know what "void*" is.

On top of that, the javac-based approach has raised some questions related to performances, as some tests seem to spend a lot of time in macro evaluation.