[Feature Request] offsetof

[procedural]

Tell me why offsetof is not possible to implement, or so hard that it's not worth it.

(feel free to move this issue to other repo if, say, it's more GLSL related than glslang related.)

[arcady-lunarg]

Historically I think there was never any need for something like this in GLSL because all data was accessed in a structured way and there wasn't anything like pointers. Also in GLSL you have much more ability to lay out structures in memory manually using layout qualifiers so you can know the exact offset of a structure member much more easily. What kind of use case are you envisioning for this?

[procedural]

Same use cases as people having here: microsoft/hlsl-specs#257

But when hlsl microsoft people ignore this issue for 7 years now, I thought you guys are more capable in this regard.

[arcady-lunarg]

The concerns in the linked issues mostly have to do with the fact that HLSL doesn't support something like the buffer_reference qualifier that allows access through a pointer in a structured way. In GLSL you can have your structure definition with a buffer_reference qualifier and then cast your pointer to that type and access whatever member directly without having to get its offset explicitly. On the other hand, I am sure there might be some cases where you really do need an explicit offset of a struct member. I suppose when you're doing structs within structs and want to go from the inner to the outer struct for example. Adding this would require writing an extension specification (it would probably be pretty straightforward though) and for that you should probably open an issue in the GLSL repository.