Silver: Visibility of operators on Generic Types

Elements Elements Bugs
1

IDE: Fire
Version: 9.0.97.2071, 9.1.100.2076 (was originally discovered in 8.4 beta 2 month ago)
Target: Java
Description:

For the Coordinate defined as:

public struct Coordinate<T: Comparable> {
	
	/*! primarily designated to store longitude in degrees */
	public var x: T
	/*! primarily designated to store latitude in degrees */
	public var y: T
	
	public init(x: T, y: T){
		self.x = x
		self.y = y
	}
	
	public static func <(lhs: Coordinate<T>, rhs: Coordinate<T>) -> Bool{
		
		//this compiles
		return Comparable.op_LessThan(lhs.x, rhs.x) && Comparable.op_LessThan(lhs.y, rhs.y)
		
		//this doesn't
		//return lhs.x < rhs.x && lhs.y < rhs.y
	}
}

both lhs and rhs are generic types with Comparable constraint. When trying to use operators on T itself, compilation will fail with: error E64: Type mismatch, cannot find operator to evaluate "T" < "T", however when actually calling the operator’s Java underlying method, it works as charm. It feels like that compiler is unaware of operator static method that are implemented on type T that implements comparable.

2

Thanks, logged as bugs://76949

3

This is an unfortunate limitation of java. On Java T isn’t retained at runtime, so there’s no way to do this with a static method. You could however use an instance method if you want to solve this problem.

4

bugs://76949 got closed with status notfixable.