duplicates:

• SR-5869 trailing closure not parsed correctly in if-statement conditional

Issue Description:

This is legal:

let ok = arr.map{$0*2}.first == 4

This is not:

 
if arr.map {$0*2}.first == 4 {
    print("yup")
}

First of all, I think it should be legal. Second, if it isn't legal, we should get better diagnostics. Right now we get

• Anonymous closure argument not contained in a closure

• Consecutive statements on a line must be separated by ';'

• Ambiguous reference to member 'map'

• Type 'Int' has no member 'first'

• Closure expression is unused

None of which is very useful.