Cannot infer literal types in a container

[Atry]

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@ repl.compiler.settings.YliteralTypes.value = true   
@ def someLiteral[SString <: String with Singleton](some: Some[SString]) = "OK" 
defined function someLiteral
@ someLiteral(Some("foo")) 
cmd5.sc:1: inferred type arguments [String] do not conform to method someLiteral's type parameter bounds [SString <: String with Singleton]
val res5 = someLiteral(Some("foo"))
           ^
cmd5.sc:1: type mismatch;
 found   : Some[String]
 required: Some[SString]
val res5 = someLiteral(Some("foo"))
                           ^
Compilation Failed

[Atry]

@milessabin Is there any way to infer it to Some["foo"] except explicit "foo".narrow?

[soronpo]

FYI, It's the same in dotty:

error: type mismatch:
 found   : Some[String]
 required: Some[String & Singleton]
someLiteral(Some("foo"))

[soronpo]

@Atry, if you want to hold on to the narrowed type, you might want to checkout TwoFace, as described here.

[milessabin]

I think this is essentially the same issue as #145 ... closing for now. We can revisit later if need be.