There are more and more issues about managing lints in Clippy popping up. Lints
are hard to implement with a guarantee of no/few false positives (FPs). One way
to address this might be to introduce more lint groups to give users the ability
to better manage lints, or improve the process of classifying lints, so that
disabling lints due to FPs becomes rare. It is important to note, that Clippy
lints are less conservative than rustc lints, which won't change in the
future.

• Add an easy way to run clippy with high FPR / trivial lints disabled #5537 (production lints)
• Missing lint categories? #6366 (suspicious group)
• Idea: Make it possible to define custom groups (in configuration file)

Steps to completion:

• Add suspicious lint group
• Start discussion about subdividing allow-by-default groups
• Better define our expectations for lint groups (regarding FPs and strictness)
• Make it possible to dump a statistics file when running Clippy (allowed lints, ...?)
• CFP: Ask people to send us their Clippy statistic files, to help evaluate lints
• Implement expect attribute (Tracking issue for RFC 2383, "Lint Reasons RFC" rust#54503)
• Go over all lints and reassign lint groups