[5.9] Two @objcImpl protocol fixes

lib/IRGen/GenClass.cpp

@@ -1228,7 +1228,7 @@ namespace {
         const ClassLayout &fieldLayout)
         : IGM(IGM), TheEntity(theUnion), TheExtension(nullptr),
           FieldLayout(&fieldLayout) {
-      visitConformances(getClass()->getImplementationContext());
+      visitConformances(getClass());
 
       if (getClass()->isRootDefaultActor()) {
         Ivars.push_back(Field::DefaultActorStorage);
@@ -1249,7 +1249,7 @@ namespace {
           FieldLayout(nullptr) {
       buildCategoryName(CategoryName);
 
-      visitConformances(theExtension->getImplementationContext());
+      visitConformances(theExtension);
 
       for (Decl *member : TheExtension->getImplementationContext()->getMembers())
         visit(member);
@@ -1295,6 +1295,15 @@ namespace {
     /// Gather protocol records for all of the explicitly-specified Objective-C
     /// protocol conformances.
     void visitConformances(const IterableDeclContext *idc) {
+      auto dc = idc->getAsGenericContext();
+      if (dc->getImplementedObjCContext() != dc) {
+        // We want to use the conformance list imported from the ObjC header.
+        auto importedIDC = cast<IterableDeclContext>(
+                                 dc->getImplementedObjCContext()->getAsDecl());
+        visitConformances(importedIDC);
+        return;
+      }
+
       llvm::SmallSetVector<ProtocolDecl *, 2> protocols;
       for (auto conformance : idc->getLocalConformances(
                                 ConformanceLookupKind::OnlyExplicit)) {

lib/Sema/TypeCheckDeclObjC.cpp

@@ -28,6 +28,9 @@
 #include "swift/AST/SourceFile.h"
 #include "swift/AST/TypeCheckRequests.h"
 #include "swift/Basic/StringExtras.h"
+
+#include "clang/AST/DeclObjC.h"
+
 using namespace swift;
 
 #pragma mark Determine whether an entity is representable in Objective-C.
@@ -3326,9 +3329,25 @@ class ObjCImplementationChecker {
     return Identifier();
   }
 
+  /// Is this member an `@optional` ObjC protocol requirement?
+  static bool isOptionalObjCProtocolRequirement(ValueDecl *vd) {
+    if (auto clangDecl = vd->getClangDecl()) {
+      if (auto method = dyn_cast<clang::ObjCMethodDecl>(clangDecl))
+        return method->isOptional();
+      if (auto property = dyn_cast<clang::ObjCPropertyDecl>(clangDecl))
+        return property->isOptional();
+    }
+
+    return false;
+  }
+
 public:
   void diagnoseUnmatchedRequirements() {
     for (auto req : unmatchedRequirements) {
+      // Ignore `@optional` protocol requirements.
+      if (isOptionalObjCProtocolRequirement(req))
+        continue;
+
       auto ext = cast<IterableDeclContext>(req->getDeclContext()->getAsDecl())
                         ->getImplementationContext();
 

test/IRGen/Inputs/objc_implementation.h

@@ -1,6 +1,6 @@
 #import <Foundation/Foundation.h>
 
-@interface ImplClass: NSObject
+@interface ImplClass: NSObject <NSCopying>
 
 - (nonnull instancetype)init;