lang: allow cfg_attr for the ix data structs

[skrrb]

allow to conditionally include attributes in the autogenerated instruction data structures

related to #2339

[vercel]

@skrrb is attempting to deploy a commit to the coral-xyz Team on Vercel.

A member of the Team first needs to authorize it.

[Aursen]

@acheroncrypto do I close my PR about it?

[acheroncrypto]

#2339 is about cfg while this PR is about cfg_attr, so I don't think you need to close it.

The reason why this PR is not merged yet is because we're trying to support invalid Rust code by using conditional derives with functions. We then have to remove this attribute from the function (because it wouldn't compile) by mutating the user's program module. Although this mutation seems fine, I'm not a fan of the nature of this code.

It would be great if we could find a better way to achieve this.

[jamie-osec]

We're cleaning up the repo and closing old PRs that may no longer be relevant. If you'd like to push this forward please open an issue with the feature request