I'm quite fond of error-chain (https://github.com/rust-lang-nursery/error-chain), which helps mitigate it somewhat. You can do things like:

    use error::{Error, ErrorKind, Result, ResultExt};
    
    fn some_func(v: &str) -> Result<u32> {
        v.parse::<u32>().chain_err(|| ErrorKind::ParseIntError)
    }

The purpose of `chain_err` here is to add on top of the previous error, to explain what you were trying to do, instead of passing up the previous error (in this case, `std::num::ParseIntError`).

If you don't like that, you can do something like this:

    use std::boxed::Box;
    use std::error::Error;

    fn some_func(v: &str) -> Result<u32, Box<Error>> {
        v.parse::<u32>().map_err(|e| Box::new(e))
    }

But then you'd have to box every error.