feat: add bound attribute

[vic1707]

fixes #1043

Tired my best to create meaningful tests, if you have better ideas please tell me!

[knoellle]

Thank you for your contribution!
I like the feature and the implementation looks good to me. Once the CI is happy, I'm inclined to merge this.

• The CI / ui check that failed should already be fixed in Pin trybuild to 1.0.89  #1049
• The lint check just needs a cargo format
• The last one needs a good sprinkle of #[allow(dead_code)] just like many of the other types in that test file. Or if you're feeling fancy you can actually instantiate the types and print them 😉.

[vic1707]

Hi,
Just rebased on latest main, applied fmt/lint, and edited the changelog.
I believe the failling CI isn't related to this PR as trybuild also fails on untouched ui tests 🤔

[knoellle]

The main CI breakage should be fixed with

• #1052

Please rebase and try again. Enable merge when ready when you're happy with it.
You will have to regenerate the stderr for your new tests with Rust 1.83 since #1052 changes the Rust version used for those tests.

[jonathanpallant]

Could we get this added to the defmt book, to explain how what the underlying issue is, and how to use this to fix it?

[vic1707]

Hi, the rebase is done, CI is passing, and I’ve added the reference 👍

Is the book request addressed to me? I have to admit I’m not sure where in the book this should go nor how best to explain it 😓

[knoellle]

Yes @vic1707, if you could add some documentation, that would be lovely.
I think adding a section in book/src/format.md should be sufficient, similar to the section about uncompressed adapters.
Having a minimal example showing usage and a few sentences about when/why its useful would be great.