I was discussing the designing of APIs for a UI framework, and the issue came up that error messages can be very opaque. As the API designers, we have more information than the compiler, and we could use this information to modify the error messages to be more useful to the downstream user. So the question is: could
rustc expose some way of modifying errors before reporting them, similar to how proc macros work on source code.
This is definitely a raw idea rather than a developed proposal. I'm just interested if the same idea has come up before?