swift234

[Constraint solver] Point at specific parameter or function in diagnostic.

When we're diagnosing an error during the initialization of a
parameter from an argument, point at the actual parameter (if we can
find it) or at least the function (if we can't) where the call
failed. Baby steps:

t2.swift:3:4: error: '(x : Int, y : Int)' is not a subtype of 'Int'
f3(f3b)
   ^
t2.swift:1:9: note: in initialization of parameter 'x'
func f3(x : (x : Int, y : Int) -> ()) {}
        ^



Swift SVN r6924