Pre-RFC: Generalizing the `backtrace` fn on `std::error::Error`

[tcsc]

@yaahc

Another benefit is that it may make the error trait easier to move out of std into either alloc or core in the future. I'm told that backtrace already supports no_std so this is a nonissue

Being able to make progress on Consider moving std::error::Error to `alloc` · Issue #62502 · rust-lang/rust · GitHub (disclaimer: I filed this issue) is a substantial benefit to people who develop crates that support no_std. Per that issue's reason for closure (requiring an RFC to figure out a way forward), I think you're a bit hasty in assuming that it's a non-issue, but maybe I'm mistaken.