casting - Swift compiler error contradicts warning when declaring lazy property -

var rawdata: nsdictionary! lazy var nativedata: nativedata? = {     return nativedata(jsondictionary: self.rawdata [nsobject : anyobject]) }() 

results in error:

'nsdictionary!' not convertible '[nsobject : anyobject]'; did mean use 'as!' force downcast?

ok then...

lazy var nativedata: nativedata? = {     return nativedata(jsondictionary: self.rawdata as! [nsobject : anyobject]) }() 

which gives warning:

forced cast 'nsdictionary!' '[nsobject : anyobject]' succeeds; did mean use 'as'?

interestingly if remove lazy , declare nativedata regular optional, can as cast fine:

obj.nativedata = nativedata(jsondictionary: obj.rawdata [nsobject : anyobject]) 

is bug in compiler? (xcode 7.3 (7d175))

update

it gets stranger. here's contained case.

// //  a.swift // import foundation  class nativedata {     init(jsondictionary: [nsobject : anyobject]) {     } }  func == (lhs: a, rhs: a) -> bool {     return lhs.id == rhs.id }  class {     var id: int64 = 0     var rawdata: nsdictionary!     lazy var nativedata: nativedata? = {         return nativedata(jsondictionary: self.rawdata [nsobject : anyobject])     }() } 

if remove func == operator definition, compiler error goes away. (in actual code, a conforms equatable.) note error doesn't occur if put code in playground.