MSRV for procfs

[eminence]

The procfs crate currently has a MSRV of 1.48, and this is verified via CI checks. However, it is increasingly difficult to actually test on 1.48 because more and more of the rust ecosystem will arbitrary change their MSRV (even in patch versions).

Our CI script is full of cargo pins to keep certain dependencies on older versions.

I am now strongly considering changing the MSRV of rust to be something way less conservative. I'm not sure exactly what it should be If anyone has any thoughts, please let me know

[eminence]

My current thinking du jour: the latest version of procfs will only be tested against the latest stable rust compiler.

But if someone needs to use procfs on an older compiler, we'll publish a table that lists what version of procfs they should use (for example, procfs v0.14 supports rust 1.48). If they need a specific bugfix backported to an older release of procfs, they can ask for that. And if they're willing to do the work, I think they can backport new features to older releases too.

[tatref]

This might be of interest: https://github.com/foresterre/cargo-msrv

[tyilo]

If you don't want to guarantee a specific MSRV, I think the rust-version field should be removed from Cargo.toml.