swift234

Type-check generic function signatures before building archetypes.

Type-check the parameter patterns and result type of a generic
function before assigning archetypes, which potentially produces a
dependent function type. Then, assign archetypes to the generic
parameters, revert all of the dependent types, and validate the types
again (now with archetypes), so the rest of the frontend can
(temporarily) continue to traffic in archetypes.

The type-check, revert, type-check behavior is a bit odd. We want to
re-process the TypeReprs because they have all of the source-location
information necessary to produce proper diagnostics, but from this
processing we will eventually need to produce two types: the type for
the signature (as viewed from the outside), which will involve generic
parameters, and the type for the definition, which will involve
archetypes.



Swift SVN r7504