[TypeChecker] Diagnose key paths with contextual type but no leading dot #30867
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This is going to be useful to detect whether contextual root is really expected during key path resolution in Sema.
If a Swift key path has root type inferred but does not have a leading dot,
then diagnose it, because it's not valid.
For example:
```swift
struct Foo {
let property: [Int] = []
let kp: KeyPath<Foo, Int> = \property.count // error
}
```
Resolves SR-12290
Resolves rdar://problem/59874355
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@theblixguy @dan-zheng This is a modified version of #30164 which got reverted because Tensorflow relied on implicit type expressions. I think this problem should be addressed now because |
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@swift-ci please smoke test |
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Thank you again for reimplementing #30164!
Just for reference: tensorflow branch may remove KeyPathIterable.allKeyPaths derived conformances in favor of a runtime metadata based implementation. That could re-enable #30164 in case this parsing-based approach is less desirable.
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I think we’d want to keep information about the leading dot just to avoid mismatches in the future. |
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@swift-ci please test source compatibility |
If a Swift key path has root type inferred but does not have a leading dot, then diagnose it, because it's not valid. For example:
Resolves SR-12290
Resolves rdar://problem/59874355