Basic Nix support

[soywod]

This PR brings Nix (Flakes) support for development shells. Basically, any Nix user that would like to contribute to the project just needs to nix-shell (or nix develop with flake support) in order to spawn a shell with the Rust environment ready to use.

Later steps could be to add apps and packages to build or test the lib. Ideally from the CI, to benefit from the reproducible build environment Nix proposes.

Useful links

• Nix/Nixpkgs/NixOS website
• Nix/Nixpkgs/NixOS GitHub repo
• Use direnv to automatically spawn Nix shells
• Nix Flakes Wiki
• Nice blog about Nix and Nix Flakes

[duesee]

Grr... bad luck. First time the CI broke like this. Will look into it. rust-lang/rustup#3709

[duesee]

Thank you very much, Clement!

I'm a bit torn. On one side, I really want Nix users to feel at home. On the other side, I'm not a (seasoned) Nix user myself and cannot really assess your work. (I have a bit Nix experience but, for example, cannot tell instantly if the flake.lock should be commited, what the compat does, etc.)

Can you say a sentence about each added file? Also, I hope you will help me out when something needs to be reviewed? :-)

Few more questions inline.

[soywod]

I'm a bit torn. On one side, I really want Nix users to feel at home. On the other side, I'm not a (seasoned) Nix user myself and cannot really assess your work. (I have a bit Nix experience but, for example, cannot tell instantly if the flake.lock should be commited, what the compat does, etc.)

I totally understand. I experienced the same feeling when someone sent me a PR for supporting Nix in Himalaya for the first time. Somehow it boosted me to learn about, and finally adopt it, but not everyone is willing to do so.

I propose to give you as much information as I can, they you guys decide to accept or not the PR?

Can you say a sentence about each added file? Also, I hope you will help me out when something needs to be reviewed? :-)

Sure, let me do this right now.

[coveralls]

Pull Request Test Coverage Report for Build 9018216518

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 64.616%

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Totals
Change from base Build 9018208028:	0.1%
Covered Lines:	893
Relevant Lines:	1382

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💛 - Coveralls

[soywod]

@duesee any idea on this mysterious CI error https://github.com/duesee/imap-flow/actions/runs/9001307954/job/24727273648?pr=173?

[duesee]

@duesee any idea on this mysterious CI error https://github.com/duesee/imap-flow/actions/runs/9001307954/job/24727273648?pr=173?

Looks like a bug in cargo-deny? I'm on the CI right now. Will merge the just stuff, then come back to this :-)

[duesee]

Thank you very much, Clement! Also for your patience and great explanations. I did a bit of research myself and start feeling more confident.

Very happy to merge this :-)

I also filed #180.