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Summary:
In some cases it would be useful to extend a generic type under some conditions for the generic argument. 

For example one could declare a protocol JSONEncodable to which all JSON types conform (e.g. Int, String, Bool, …). Each array of these types is JSON encodable as well and should also conform to JSONEncodable if it only contains elements that conform to JSONEncodable. However, writing an extension of Array like the following gives the error: Extension of type 'Array' with constraints cannot have an inheritance clause

extension Array: JSONDecodable where Element: JSONDecodable

Steps to Reproduce:
Open the sample project and try to compile it

Expected Results:
The code should compile and the array should conform to JSONEncodable if and only if its elements are JSONEncodable

Actual Results:
The code does not compile

Version:
Xcode 7.1 (7B91b)

Notes:


Configuration:


Attachments:
'SampleProject.zip' was successfully uploaded.
Sample project contains the following code:

protocol JSONEncodable {}

extension Int: JSONEncodable {}
extension String: JSONEncodable {}

extension Array: JSONEncodable where Element: JSONEncodable {
}