Open Radar

 
I have a Result<T> type that supports monadic flow control methods.  The methods are overloaded in two versions:

* One overload takes a function that returns the monadic type: () -> Result<()>

* Other overload takes a function that returns Void: () -> ()

In Swift 1.1, this code compiled and ran correctly.  In Swift 1.2 it fails to compile.  The error message reports an ambiguous overload.

Steps to Reproduce:
1. Create Swift project in Xcode.
2. Implement Result<T> type and monadic flow control methods in Swift.
3. Implement test of Result<T> type and monadic flow control.

Expected Results:
Xcode compiles the Swift code and tests succeed. 

Actual Results:
Xcode 6.3b1 fails to compile the attached file.

The error message in Xcode 6.3b1:

/Users/jay/Coding/Swift/TrySwift/TryThenWhile/TryThenWhile.swift:137:19: error: ambiguous use of 'thenWhile'
        let rs4 = Result(s1)
                  ^
/Users/jay/Coding/Swift/TrySwift/TryThenWhile/TryThenWhile.swift:80:17: note: found this candidate
    public func thenWhile(@autoclosure test:  () -> Bool, body: () -> Result<()>) -> Result<()> {
                ^
/Users/jay/Coding/Swift/TrySwift/TryThenWhile/TryThenWhile.swift:98:17: note: found this candidate
    public func thenWhile(@autoclosure test:  () -> Bool, body: () -> ()) -> Result<()> {
                ^
/Users/jay/Coding/Swift/TrySwift/TryThenWhile/TryThenWhile.swift:156:15: error: enum case pattern cannot match values of the non-enum type '<<error type>>'
        case .Success(let res): XCTAssertEqual(res.unbox, 10, "Test 4 should have succeeded")
              ^
/Users/jay/Coding/Swift/TrySwift/TryThenWhile/TryThenWhile.swift:157:15: error: enum case pattern cannot match values of the non-enum type '<<error type>>'
        case .Failure(_): XCTFail("Test 4 failed")