Usage with proc macros

[torsteingrindvik]

Hi, great lib, thanks for making it!

I've just started using it so I'm not sure about the possibilities/limitations yet.
Couldn't find this question anywhere:

Is it possible to use when writing proc macros in a neat way?

I saw the panic_hook example which I think I could possibly use to

• Write proc macros as usual
• Call unwrap() on fallible function calls in the proc macro impl
• It might work?

Not sure how the proc macro span stuff will integrate with this (if it works).

I will experiment a bit with this, but perhaps you have some pointers for how to best do this.

[yaahc]

Hi, great lib, thanks for making it!

😳

Is it possible to use when writing proc macros in a neat way?

Sounds doable, depending what you have in mind, however I don't see how this ties in with eyre in specific. Happy to help either way, but I expect you'll want to write your own panic hook and just use that directly to format messages provided via panic! from the proc-macro.

The main issue I foresee you running into is that panic! discards most information about the type used to create the error when one is turned into a panic. The hook only ends up getting a &str or a String most of the time. Right now there are ways around this, for example if you panic directly with panic!(expr) it will type erase the payload as a dyn Any instead of stringifying it, which you can then downcast back to the correct type, which would potentially help you get rich error reports.

I will experiment a bit with this, but perhaps you have some pointers for how to best do this.

I look forward to hearing how it goes! I'd potentially be interested in adding this to spandoc and displaydoc.