CI appears to be failing on all branches on rust v1.51

[DeWarner]

CI appears to be failing on all branches when using rust version 1.51
example: https://github.com/tomaka/rouille/runs/6828755515?check_suite_focus=true
this is the issue rust-lang/rust#81110
it is fixed in 1.52, however
1.52 requires cargo-features = ["edition2021"]
and this feature is not stabilised until 1.56.
One solution is to drop support for 1.51 and make 1.56 the minimum supported version. #260
However this needs to be considered for the impact it will have on projects utilising the framework.
Since its failing to compile time I don't think there is anything else that can be done.

[bradfier]

Time has a frustrating MSRV policy summarised as "the last six months", given Rust's release cadence basically means the last 4 point releases.

We can consider pinning time but you might be right and moving to 1.56 could be easier.

[DeWarner]

Time seems to be running away from us...
I think that since this will continue to break regularly we should pin time within a range so that it no longer breaks the builds, and then have a recurring task to routinely update time + msrv (perhaps something like dependabot could help with this?).
I might be wrong about this but if we dont pin time and just continue to increment MSRV would that have the effect that older projects using rouille would not be able to compile their projects that could previously compile, without first having to update the rust version that their project is using?

[bradfier]

Yeah that's my concern with continually updating it like this.

We can probably pin the version without any ill effect if we don't export the type but I'd have to go and check if we leak it anywhere.

[bradfier]

Closing as we dropped the mandatory test on old Rust versions and will just deal with issues as they arise.