Hi Remy, We have fixed a related issue here: https://github.com/openjdk/jextract/pull/101 Hopefully this addresses your problem. Cheers Maurizio On 30/01/2023 16:39, Maurizio Cimadamore wrote:

Hey Remi, while jextract does not support bitfields, it should also not crash when seeing them :-)

I have tried extracting a simple header containing the struct in your email using the jextract binary at [1].

I could successfully extract it, and obtain a |my_struct| Java wrapper, with this layout:

|static final GroupLayout $struct$LAYOUT = MemoryLayout.structLayout( MemoryLayout.structLayout( MemoryLayout.paddingLayout(1).withName("foo"), MemoryLayout.paddingLayout(31) ) ).withName("my_struct"); |

As expected, the contents of the struct are just padding.

That said, I’m beginnin to suspect that you are seeing this issue with a more recent version of jextract, perhaps the one for the “panama” branch? We have made recent changes to how padding layouts are defined - e.g. so that their size/alignment must be a multiple of 8. This would cause the issue you are seeing.

Maurizio

On 30/01/2023 13:25, Rémy Maucherat wrote:

...

Hi,

When processing certain bit-fields, jextract produces an error: "Invalid bitSize: 1" In addition to not being really helpful (it took me some time to find out what the problem was since no reference to a location is given, nor that this is about a bit-field).

A typical example causing the error is something like: struct my_struct { unsigned int foo : 1; };

Obviously we don't have these sort of memory saving "smart" fancy tricks in Java (which is probably good since they can cause serious problems when misused ...).

Is support for this planned eventually, or should bit-fields be avoided for Panama compatibility ?

Thanks !

Rémy ​