[NoncopyableGenerics] misc fixes and improvements

Author: kavon

include/swift/AST/TypeRepr.h

@@ -1325,7 +1325,7 @@ class ExistentialTypeRepr: public TypeRepr {
   friend class TypeRepr;
 };
 
-/// A type repr represeting the inverse of some constraint. For example,
+/// A type repr representing the inverse of some constraint. For example,
 ///    ~Copyable
 /// where `Copyable` is the constraint type.
 class InverseTypeRepr : public TypeRepr {

lib/AST/Type.cpp

@@ -523,7 +523,7 @@ bool TypeBase::isDistributedActor() {
 }
 
 llvm::Optional<KnownProtocolKind> TypeBase::getKnownProtocol() {
-  if (auto protoTy = this->castTo<ProtocolType>())
+  if (auto protoTy = this->getAs<ProtocolType>())
     if (auto protoDecl = protoTy->getDecl())
       return protoDecl->getKnownProtocolKind();
 

lib/Sema/TypeCheckInvertible.cpp

@@ -254,6 +254,7 @@ bool StorageVisitor::visit(NominalTypeDecl *nominal, DeclContext *dc) {
     return false;
   }
 
+  assert(!isa<ProtocolDecl>(nominal) || !isa<BuiltinTupleDecl>(nominal));
   return false;
 }