[IRGen] Look through opaque types for protocol witness table lazy access function.

When determining the linkage of protocol witness table lazy access
functions and their cache variables, look through opaque types to find
the underlying decls.

rdar://96194366

Author: nate-chandler

lib/IRGen/Linking.cpp

@@ -765,7 +765,13 @@ SILLinkage LinkEntity::getLinkage(ForDefinition_t forDefinition) const {
 
   case Kind::ProtocolWitnessTableLazyAccessFunction:
   case Kind::ProtocolWitnessTableLazyCacheVariable: {
-    auto *nominal = getType().getAnyNominal();
+    auto ty = getType();
+    ValueDecl *nominal = nullptr;
+    if (auto *otat = ty->getAs<OpaqueTypeArchetypeType>()) {
+      nominal = otat->getDecl();
+    } else {
+      nominal = ty->getAnyNominal();
+    }
     assert(nominal);
     if (getDeclLinkage(nominal) == FormalLinkage::Private ||
         getLinkageAsConformance() == SILLinkage::Private) {

validation-test/compiler_crashers_fixed/rdar96194366.swift

@@ -0,0 +1,16 @@
+// RUN: %target-swift-frontend -target %target-cpu-apple-macosx10.15 -swift-version 5 -c %s
+// REQUIRES: objc_interop
+// REQUIRES: OS=macosx
+
+import SwiftUI
+
+struct DropDestinationCoordinatorView: NSViewRepresentable {
+	func makeNSView(context: Context) -> some NSView {
+    return NSView()
+	}
+	
+	func updateNSView(_ nsView: NSViewType, context: Context) {
+		print("for view:  \(nsView)")
+	}
+}
+