[epic] False Positive tracking / triaging / categorization

This follows this discussion on Zulip

The aim of this issue is to track effort to reduce False Positive rate, and potentially categorize things into common patterns.

Obviously there are many more, and I will keep adding them as I go.

• while_let_loop
  • while_let_loop false positive #1693
  • while_let_loop should not be reported for empty match statements #10037
• get_unwrap | False positive?: get_unwrap #1725
• useless_if_let_seq| useless_if_let_seq should not warn for composite ifs #1089
• op_ref | op_ref false positive #2042
• match_same_arms
  • match_same_arms: FP if arms have different comments #12044
  • Another false positive: match_same_arms vs. &Any #1218
• while_immutable_condition | while_immutable_condition false positive with mut pointers #3548
• boxed_local
  • False positive for boxed local with wasm_bindgen #4351
  • boxed_local false positive for ?Sized #4740

Could be closed(?)

• lint against using a binding whose name is prefixed with an underscore #488 (@blyxyas)
• False positive in derive_hash_xor_eq with multiple Eq implementations #2025 (@Jarcho)
• clippy::new_without_default_derive triggers and shouldn't #3697 (@flip1995)
• Clippy reports map with identity function on functions that perform implicit conversion #12043 (already fixed through [map_identity]: respect match ergonomics #11792)

Have PR

• float_cmp | float_cmp false positive: catching underflow #2834 | float_cmp changes #11948 (@Jarcho)

Macros

This category is concerned with FPs that involve macros, and their expansions.

• iter_without_into_iter | iter_without_into_iter fires on code generated by macros from other crates #12037
• struct_field_names | Consider silencing struct_field_names for structs with derive(Serialize/Deserialize) #12035
• redundant_closure_call
  • redundant_closure_call triggered when closure is a macro parameter #11274 | (duplicate of redundant_closure_call false positive in macros #1553 ?).
  • redundant_closure_call false positive in macros #1553
  • PR: Fixed FP in redundant_closure_call when closures are passed to macros #12082
• unnecessary_mut_passed | False positives selecting system allocator #2373
• zero_ptr | False positives selecting system allocator #2373
• no_effect_underscore_binding | no_effect_underscore_binding: FP on field inside derive macros #12045

May need discussion

• eq_op | lint against using a binding whose name is prefixed with an underscore #488

Meta

@flip1995 wanted to automate issue tracking / impl issue finder for lint names in #5049. Perhaps it's needed because it's a lot of manual effort :D

@rustbot label +C-tracking-issue

The boxed_local ones need a minor change on their lint message and are good to go.

[felix91gr]

@PartiallyUntyped the useless_if_let_seq issue has been closed by now. I'm pinging you so that you know you can mark that one checkbox as ☑ c:

[blyxyas]

Done! ☑ =^w^=