[swift-users] Overload Resolution of Binary Operators

[Rien]

I seem to remember that while it is possible to define, the compiler will yield an error if you try to use the functions (“cannot resolve”).

Regards,
Rien

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> On 14 Nov 2016, at 23:05, Toni Suter via swift-users <swift-users at swift.org> wrote:
> 
> Hi,
> 
> I would have expected that the following code reports an error, because
> of ambiguous function overloads:
> 
> infix operator ***: MultiplicationPrecedence
> infix operator +++: AdditionPrecedence
> 
> func ***(x: Int, y: Int) -> String {
> 	print("f1")
> 	return ""
> }
> 
> func ***(x: Int, y: Int) -> Int {
> 	print("f2")
> 	return 0
> }
> 
> func +++(x: String, y: Int) -> Int {
> 	print("f3")
> 	return 0
> }
> 
> func +++(x: Int, y: Int) -> Int {
> 	print("f4")
> 	return 0
> }
> 
> let result = 0 *** 4 +++ 0		// prints f2 and f4
> 
> 
> As far as I can tell, there are two possible overload resolutions: f1 + f3 or f2 + f4.
> I thought that these two solutions get an "equivalent score" and therefore there would
> be a compile error. However, that's not the case. Instead, the type checker picks
> f2 and f4.
> 
> So, I guess my question is, whether there is some rule, that prefers
> operators, which have the same argument types and the same return type
> or whether this is simply a bug.
> 
> Thanks and best regards,
> Toni
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