[SR-11588] Warn about derived Hashable implementation if there's a custom Equatable
#53.993 aberto em 8 de out. de 2019
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Description
| Previous ID | SR-11588 |
| Radar | rdar://problem/55792988 |
| Original Reporter | @beccadax |
| Type | Improvement |
| Status | In Progress |
| Resolution |
| Votes | 0 |
| Component/s | Compiler |
| Labels | Improvement, DerivedConformance, StarterBug |
| Assignee | @JGiola |
| Priority | Medium |
md5: 023a941f08cf5b893763b728c33c0c83
relates to:
- SR-14665 Synthesised Equatable may be incorrect for manually implemented Comparable
Issue Description:
Types that have a custom == almost surely also require a custom Hashable conformance (i.e. the synthesized one will be wrong). Ideally, we wouldn’t synthesize if there’s a custom equatable, but that’s not source-stable. The compiler should emit a warning if it synthesizes a Hashable conformance for a type whose ==(Self, Self) -> Bool implementation is not also synthesized.
This should be relatively simple to do: in the "full Hashable derivation" part of DerivedConformanceEquatableHashable.cpp, after we have decided that we are definitely going to derive an implementation, find the == operator in the type's Equatable conformance and see if it isImplicit(). If it is, emit a warning.