swiftlang/swift
[SR-5819] Suggest `as? AnyHashable` when `as? Equatable` or `as? Hashable` is attempted
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#48,389 opened on 2017/09/01
bugcompilerdiagnostics qualitygood first issue
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説明
| Previous ID | SR-5819 |
| Radar | None |
| Original Reporter | @jckarter |
| Type | Bug |
| Votes | 0 |
| Component/s | Compiler |
| Labels | Bug, DiagnosticsQoI, StarterBug |
| Assignee | None |
| Priority | Medium |
md5: 5e4ffb6d40f711123adf86651f9a3a8f
Issue Description:
If you have two values of type Any or otherwise opaque type and you want to test whether they're equal, it's natural to try to write something like:
if let a = a as? Equatable, b = b as? Equatable {
return a == b
}
Maybe someday that will work, but in the meantime dynamically casting to AnyHashable can get the desired effect. It'd be nice QoI to have a diagnostic telling people they can do this when they try similar things that don't.