Open Radar

 
Summary:
Swift fails to link projects which declare Hashable & Equatable conformance for the same type in two separate files.


Steps to Reproduce:
1. Declare a new type.
2. In separate files, explicitly conform it to Hashable & Equatable respectively using extensions, implementing the requirements for those protocols.
3. Build.


Expected Results:
I expected it to build & run just fine; the explicit conformance to Equatable is redundant, but not unreasonable as documentation.


Actual Results:
Instead, it fails with linker errors.


Regression:
This works fine if both extensions are in the same file.


Notes:
Code listing as follows:

File A:
struct Thing {
    let value: Int
}

File B:
extension Thing : Hashable {
    var hashValue: Int { return value }
}

File C:
extension Thing : Equatable {}
func == (a: Thing, b: Thing) { return a.value == b.value }