Fix a layout discrepancy when an associated type had @objc protocol constraints, in which case WitnessTableLayout would reserve a slot for the witness table, but WitnessTableBuilder would never emit it. Also add assertions to WitnessTableBuilder that check that the witness table we're building follows the claimed WitnessTableLayout. Fixes rdar://problem/20418117.
Swift SVN r26953
Make WitnessVisitor not freak out when it sees an init requirement, allowing 'init' requirements to be used in non-@objc protocols. Fixes <rdar://problem/13695680>.
Swift SVN r14744
Previously, TypeAliasDecl was used for typealiases, generic
parameters, and assocaited types, which is hideous and the source of
much confusion. Factor the latter two out into their own decl nodes,
with a common abstract base for "type parameters", and push these
nodes throughout the frontend.
No real functionality change, but this is a step toward uniquing
polymorphic types, among other things.
Swift SVN r7345
Reserve slots in protocol witness table layout to drop in associated type metadata and witnesses. To actually populate these, we'll need to move the ABI to lazy conformance-instantiation functions.
Swift SVN r6702
The value witnesses are always available through type metadata (through an extra indirection). Saving that indirection costs 16 words (and growing!) in every witness table, and when we start instantiating conformances for generic instances, would require us to instantiate practically every generic witness table. Removing the value witnesses from the protocol witness table means we will only need to instantiate witness tables when associated types are dependent on the conforming type's type variables.
This is an ABI break, but should have no user-visible functional change.
Swift SVN r6651
This is kindof a pain in a few places where the type system
doesn't propagate canonicality. Also, member initializations
are always direct-initializations and so are allowed to use
explicit constructors, which is a hole in our canonicality
tracking. But overall I like the idea of always working
with canonical types.
Swift SVN r2893
