add lint infallible_try_from

[ComputerDruid]

Looks for TryFrom implementations with uninhabited error types and suggests to implement From instead.

Fixes #2144

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changelog: Add [infallible_try_from] lint

[rustbot]

r? @blyxyas

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[ComputerDruid]

r? @llogiq

Written at the workshop during RustWeek

[llogiq]

This is a good start. The code is still failing dogfood, where clippy lints itself. Looking at the suggestions, you should change the "default lint description" in the lint definition block, and use a sym instead of comparing idents with strs in line 55. Apart from that, I have only a very small nit. Once that's dealt with, I'll start the Final Comment Period for adding this lint.

[ComputerDruid]

Should be ready to go now

[llogiq]

Thank you! I've just started the final comment period. In the meantime, can you please squash your commits?

[ComputerDruid]

Thanks! Squashed

[llogiq]

Small heads-up: Your lint is well received. There is some discussion about the lint group though. It may end up in style or sus, depending on the outcome of my poll. Don't change anything just yet, I'll keep you updated.

[llogiq]

And another update: Looks like it should go into the sus group. The FCP should end in three days, until then you have time to change the group.