DougGregor

#if canImport(Darwin)
import Darwin
#elseif canImport(Glibc)
import Glibc
#endif

actor class Counter {
  private var value = 0
  private let scratchBuffer: UnsafeMutableBufferPointer<Int>

DougGregor

diff --git a/stdlib/public/runtime/MetadataLookup.cpp b/stdlib/public/runtime/MetadataLookup.cpp
index 49ff72a487a..472dcbe0afd 100644
--- a/stdlib/public/runtime/MetadataLookup.cpp
+++ b/stdlib/public/runtime/MetadataLookup.cpp
@@ -237,7 +237,8 @@ struct TypeMetadataPrivateState {
   llvm::DenseMap<llvm::StringRef,
                  llvm::TinyPtrVector<const ContextDescriptor *>>
     ContextDescriptorCache;
-  size_t ContextDescriptorLastSectionScanned = 0;
+  size_t ConformanceDescriptorLastSectionScanned = 0;

DougGregor

Implementing Recursive Protocol Constraints

Recursive protocol constraints are a small-looking feature (really, eliminating a limitation that feels arbitrary to users) that can also greatly improve the standard library. However, their implementation will require a number of changes throughout the Swift compiler. This document attempts to catalogue the kinds of changes required in the compiler to implement this feature, to provide some scoping and direction for the work.

ArchetypeBuilder

The ArchetypeBuilder is responsible for processing the requirements in a protocol, generic function, generic type, or extension of a generic type to determine whether they are consistent. It also plays a central role in producing and canonicalizing generic signatures, as well as producing archetypes for a generic signature in a given generic environment. It is where recursive protocol constraints are detected and diagnosed, and the primary place where we will need to deal with recursion.

Lazily expand nested t

DougGregor

protocol Fooable {
  associatedtype Foo
}

protocol Barrable {
  associatedtype Bar: Fooable
}

struct X {}
struct Y: Fooable {

DougGregor

protocol P { }

protocol Q {
	associatedtype A: P
}

protocol R: Q {
	associatedtype A: P
}

DougGregor

  protocol P {
      associatedtype PType
  }

  public protocol Q {
      associatedtype QType: R
  }

  public protocol R {
      associatedtype RType

DougGregor

protocol P { }

protocol Q {
  associatedtype Assoc
  func assoc() -> Assoc
}

protocol R : Q {
  associatedtype Assoc: P
}