Solutions : expected struct TryFromIntError, found struct anyhow::Error

[DaviRain-Su]

error[E0271]: type mismatch resolving <u64 as TryFrom<usize>>::Error == anyhow::Error
--> /Users/davirain/.cargo/git/checkouts/ics23-fbd6714e79a75cb1/5a0206f/rust/src/ops.rs:71:28
|
71 | let size: u64 = length.try_into()?;
| ^^^^^^^^ expected struct TryFromIntError, found struct anyhow::Error

Compiling getrandom v0.2.3
For more information about this error, try rustc --explain E0271.
error: could not compile ics23 due to previous error
warning: build failed, waiting for other jobs to finish...
error: build failed

When I added ics23 to substrate for testing to see if the error reported by no_std was well supported.

[hu55a1n1]

Thanks for the PR @DaviRain-Su and thanks for this awesome library @ethanfrey! 🙏
It would be great if we could merge this because the ics23 crate fails to build in no_std mode currently and this PR fixes it. We're using this in our ibc-rs project and this issue is blocking our release.

Here's some context on the underlying cause of this issue ->

Since the ?-based error conversions would normally rely on the std::error::Error trait which is only available through std, no_std mode will require an explicit .map_err(Error::msg) when working with a non-Anyhow error type inside a function that returns Anyhow’s error type.

https://docs.rs/anyhow/1.0.44/anyhow/#no-std-support

[ethanfrey]

@hu55a1n1 Thanks for bumping this issue and explaining why it was needed. It seems like follow up from #41

Note the pr review and my request for proper testing and cleanup of the no_std work in #42

If you want to take over getting no_std work merged, I would be happy. I would ask.

1. rebase this pr.
2. write at least one test to show the old code breaks, the new code works. If it is urgent, I can merge without tests, but prefer not to.
3. Commit to taking over No-std cleanup #42 and possibly the trait prost::Message is not implemented for ics23::ProofSpec #46 so the no_std work is properly tested and doesn't turn into urgent requests under someone else's release timeline.

I know little about no_std but happy to merge if things are properly tested and covered by ci.

[ethanfrey]

Replaced by #54 (same code rebased)