Lower MSRV to 1.65

[DaniPopes]

Synopsis

The MSRV bump in #300 is unnecessary. The 1.72 minimum is only needed for tests, but the actual implementation depends on 1.65.

Solution

Lower MSRV from 1.72 to 1.65. Only build instead of test in MSRV CI job.

Checklist

• Documentation is updated (if required)
• Tests are added/updated (if required)
• CHANGELOG entry is added (if required)

[tyranron]

@DaniPopes thanks for taking care of the details!

@JelteF please, update the required CI jobs in project settings, and merge.

[tyranron]

ping @JelteF

[JelteF]

I think it might be nice to have a bit higher MSRV than strictly necessary, because we'll likely keep it the same for the next few years. So I'm not sure we should merge this PR

[tyranron]

@JelteF treating MSRV via SemVer of the crate seems to be quite uncomfortable: either we change the major version when don't really break API, or we are committed to not use newer Rust features until the real API break happens.

Considering that MSRV is not that much of the demand for end users (people tend to use newer versions of Rust), we could clearly state (in README) and separate this in the following manner:

• Changing MSRV is treated as a minor version in terms of SemVer.
• So, If you're not concerned about MSRV in your projects, you just use the default caret requirement: derive_more = "1", or derive_more = "1.0", or derive_more = "^1.0".
• However, if you're concerned about MSRV in your projects, then just use the tilde requirement to omit breaks: derive_more = "~1.0", or derive_more = "~1.0.0"

[tyranron]

@JelteF ping

[tyranron]

@JelteF ping

[JelteF]

I think your proposal sounds good, but we should update the readme accordingly

[tyranron]

@JelteF I've added "MSRV policy" section to README.

I've also returned running cargo test in msrv CI job, because it's vital to check macro expansion too for MSRV. Anything that doesn't fit MSRV from user-side in tests, I've hidden under the #[cfg(not(msrv))].

I'll merge this tomorrow, so you can have a look if you want to.