swift234

SILGen: Handle abstraction differences involving single-element labeled tuples.

In a case like:

protocol LabeledRequirement {
  func method(x: Loadable)
}

struct UnlabeledWitness : LabeledRequirement {
  func method(_: Loadable) {}
}

The original requirement type is represented as a labeled single-element TupleType, and the witness is represented as a scalar, but we want to disregard the label and consider the scalars in parallel. Do a pre-pass to strip single-element labels first before trying to destructure or indirect tuples.

Swift SVN r11580