Error when using automock for variadic functions

[Enes1313]

Hello,
I'm encountering an error when using automock for variadic functions in the Mockall. The relevant code snippet is as follows:

How can I resolve this error?

[asomers]

lol, the popup error is covering up the function that you're trying to mock. Better just to write your question in plaintext rather than use an image.

But the answer is that you can't. Mockall can't mock variadic functions because Rust doesn't have variadic functions. The best that you can do will probably be to manually write a variadic macro that turns its arguments into a Vec and then passes them to a automock'd function.

[Enes1313]

Thank you for your response.

I sent the image because I believed the area covered by the popup error was insignificant, and I thought it was a simple matter. I will try to write in plain text next time :) I'm sorry.

I thought that maybe there could be a solution if some changes were made to Mockall using the features described in this RFC: https://rust-lang.github.io/rfcs/2137-variadic.html.

And there was such a link. That's why I thought there could be a solution.

https://www.subarctic.org/interfacing_c_variadic_functions_in_rust.html

[asomers]

Yeah, I've seen that RFC too. Mockall could be extended to deal with it, but the feature would necessarily be unstable and gated on the nightly feature. I haven't had a need for it, nor heard much demand for it, so I haven't implemented it.

[Enes1313]

Thank you for the answer. My main goal is a hierarchy and order to prepare unit and integration tests in Rust language for C projects. That's why bindgen and mockall projects are very important for me :). I wonder if this feature can be added even if it is a nightly feature? I can try to implement it too, if you're going to enable such a property. Apart from that, if you anticipate that there will be other big problems in my goal, I can listen to them as well from you.

Edit: I'll try to do your first solution suggestion first.

[asomers]

Yes, it would be nice to have, gated by nightly of course. Would you be willing to try implementing it?

[Enes1313]

I edited the top comment before your new message :).

First of all, I will try to do your first suggestion. If I can't, I will try implement the nightly feature.

[asomers]

PR #508 shows an example of using variadic functions. However, the variadic arguments aren't currently available to the matcher and returner functions. That feature could be added. However, it probably won't be possible to use a .with() matcher. Only .withf() matchers will be possible, due to lifetime problems, similar to how #[concretize] works. I'm going to close this issue now, and defer this enhancement to the future.

Please open a new issue if anybody needs that feature.