add custom derives callback

[ericseppanen]

This callback allows us to specify arbitrary derive attributes for each named struct. This is useful for adding things that can't easily be implemented separately, such as serde::Deserialize or zerocopy::FromBytes.

This addresses the easiest cases of #1089.

There aren't any tests yet-- I'm not sure what the best way would be to test this, since it can't be reduced to a command line.

[emilio]

Thanks, this looks good but needs a test. You can add one to e.g. bindgen-integration perhaps?

[ericseppanen]

I added a test to bindgen-integration, and verified that the test fails if the add_derives callback isn't working.

[emilio]

Thank you!

[ericseppanen]

Is there anything I can do to help drive this change forward?

[emilio]

No, sorry, I've been just on vacation most of June, will merge+release asap :)

[ericseppanen]

I'm happy to hear that. If there is any follow-up work needed, I'm happy to help contribute.

[a-cristi]

Is there a way of adding a custom derive when using the CLI tool?

[ericseppanen]

@a-cristi Unfortunately, no. I couldn't imagine how the CLI would work, and I wasn't sure whether it would be useful, so I didn't even try.

My opinion doesn't matter much (I'm not a regular contributor to this crate), so feel free to open a new issue to discuss the benefits of adding CLI support.

[a-cristi]

@a-cristi Unfortunately, no. I couldn't imagine how the CLI would work, and I wasn't sure whether it would be useful, so I didn't even try.

My opinion doesn't matter much (I'm not a regular contributor to this crate), so feel free to open a new issue to discuss the benefits of adding CLI support.

I was thinking that it could work like --with-derive-default for example, by simply deriving something for all types. Something like --with-custom-derives=Foo,Bar will just end up adding a #[derive(Foo, Bar)] for every type.