From b89ef78ce5be633981f7935ab3e728a578cb5120 Mon Sep 17 00:00:00 2001
From: Joe Groff <jgroff@apple.com>
Date: Thu, 28 May 2020 14:10:39 -0700
Subject: [PATCH 1/3] Adding `final` to public API is API-stable.

Client code can't override or subclass a `public` declaration already, so although the ABI differs, the API is the same
whether something is `final` or not.
---
 include/swift/AST/Attr.def         | 2 +-
 test/api-digester/Outputs/Cake.txt | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/swift/AST/Attr.def b/include/swift/AST/Attr.def
index 8054500c3b772..95504c3477426 100644
--- a/include/swift/AST/Attr.def
+++ b/include/swift/AST/Attr.def
@@ -126,7 +126,7 @@ DECL_ATTR(available, Available,
 CONTEXTUAL_SIMPLE_DECL_ATTR(final, Final,
   OnClass | OnFunc | OnAccessor | OnVar | OnSubscript |
   DeclModifier |
-  ABIBreakingToAdd | ABIBreakingToRemove | APIBreakingToAdd | APIStableToRemove,
+  ABIBreakingToAdd | ABIBreakingToRemove | APIStableToAdd | APIStableToRemove,
   2)
 DECL_ATTR(objc, ObjC,
   OnAbstractFunction | OnClass | OnProtocol | OnExtension | OnVar |
diff --git a/test/api-digester/Outputs/Cake.txt b/test/api-digester/Outputs/Cake.txt
index 2ca2dc6739d81..a794079a71f9e 100644
--- a/test/api-digester/Outputs/Cake.txt
+++ b/test/api-digester/Outputs/Cake.txt
@@ -40,7 +40,6 @@ cake: TypeAlias TChangesFromIntToString.T has underlying type change from Swift.
 /* Decl Attribute changes */
 cake: Enum IceKind is now without @frozen
 cake: Func C1.foo1() is now not static
-cake: Func FinalFuncContainer.NewFinalFunc() is now with final
 cake: Func HasMutatingMethodClone.foo() has self access kind changing from Mutating to NonMutating
 cake: Func S1.foo1() has self access kind changing from NonMutating to Mutating
 cake: Func S1.foo3() is now static

From be8674ea73551cfa1e91ab3a3e3f52f712c3428b Mon Sep 17 00:00:00 2001
From: Joe Groff <jgroff@apple.com>
Date: Thu, 28 May 2020 18:19:03 -0700
Subject: [PATCH 2/3] Make an internal KeyPath helper final.

And remove an unnecessary override, so that further work will allow this method not to need a
vtable entry.
---
 stdlib/public/core/KeyPath.swift | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/stdlib/public/core/KeyPath.swift b/stdlib/public/core/KeyPath.swift
index dcedf5aa4c79d..53930842b2981 100644
--- a/stdlib/public/core/KeyPath.swift
+++ b/stdlib/public/core/KeyPath.swift
@@ -134,6 +134,7 @@ public class AnyKeyPath: Hashable, _AppendKeyPath {
   
   // Prevent normal initialization. We use tail allocation via
   // allocWithTailElems().
+  @available(*, unavailable)
   internal init() {
     _internalInvariantFailure("use _create(...)")
   }
@@ -158,7 +159,7 @@ public class AnyKeyPath: Hashable, _AppendKeyPath {
     return result
   }
   
-  internal func withBuffer<T>(_ f: (KeyPathBuffer) throws -> T) rethrows -> T {
+  final internal func withBuffer<T>(_ f: (KeyPathBuffer) throws -> T) rethrows -> T {
     defer { _fixLifetime(self) }
     
     let base = UnsafeRawPointer(Builtin.projectTailElems(self, Int32.self))
@@ -348,14 +349,6 @@ public class ReferenceWritableKeyPath<
 
   internal final override class var kind: Kind { return .reference }
   
-  internal final override func _projectMutableAddress(
-    from base: UnsafePointer<Root>
-  ) -> (pointer: UnsafeMutablePointer<Value>, owner: AnyObject?) {
-    // Since we're a ReferenceWritableKeyPath, we know we don't mutate the base
-    // in practice.
-    return _projectMutableAddress(from: base.pointee)
-  }
-  
   @usableFromInline
   internal final func _projectMutableAddress(from origBase: Root)
       -> (pointer: UnsafeMutablePointer<Value>, owner: AnyObject?) {

From 24336465c0e7f8a1f885de97fbff95b5640a925c Mon Sep 17 00:00:00 2001
From: Joe Groff <jgroff@apple.com>
Date: Fri, 29 May 2020 14:30:02 -0700
Subject: [PATCH 3/3] Add debug output for vtable layout

---
 lib/IRGen/GenMeta.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/lib/IRGen/GenMeta.cpp b/lib/IRGen/GenMeta.cpp
index 7eca86628b80c..22effa95297e3 100644
--- a/lib/IRGen/GenMeta.cpp
+++ b/lib/IRGen/GenMeta.cpp
@@ -14,6 +14,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#define DEBUG_TYPE "type-metadata-layout"
+
 #include "swift/ABI/MetadataValues.h"
 #include "swift/ABI/TypeIdentity.h"
 #include "swift/AST/ASTContext.h"
@@ -1520,6 +1522,15 @@ namespace {
     void addVTable() {
       if (VTableEntries.empty())
         return;
+      
+      LLVM_DEBUG(
+        llvm::dbgs() << "VTable entries for " << getType()->getName() << ":\n";
+        for (auto entry : VTableEntries) {
+          llvm::dbgs() << "  ";
+          entry.print(llvm::dbgs());
+          llvm::dbgs() << '\n';
+        }
+      );
 
       // Only emit a method lookup function if the class is resilient
       // and has a non-empty vtable.