[SE-0095] [Runtime], [Demangler], & AST printer updated to new composition syntax

- All parts of the compiler now use ‘P1 & P2’ syntax
- The demangler and AST printer wrap the composition in parens if it is
in a metatype lookup
- IRGen mangles compositions differently
    - “protocol<>” is now “swift.Any”
    - “protocol<_TP1P,_TP1Q>” is now “_TP1P&_TP1Q”
- Tests cases are updated and added to test the new syntax and mangling

Author: joewillsher

include/swift/AST/Types.h

@@ -3476,7 +3476,7 @@ END_CAN_TYPE_WRAPPER(ProtocolType, NominalType)
 /// \code
 /// protocol P { /* ... */ }
 /// protocol Q { /* ... */ }
-/// var x : protocol<P, Q>
+/// var x : P & Q
 /// \endcode
 ///
 /// Here, the type of x is a composition of the protocols 'P' and 'Q'.

lib/AST/ASTPrinter.cpp

@@ -3294,6 +3294,12 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
       return !arch->isOpenedExistential();
     }
 
+    case TypeKind::ProtocolComposition: {
+      // 'Any' and single protocol compositions are simple
+      auto composition = type->getAs<ProtocolCompositionType>();
+      return composition->getProtocols().size() <= 1;
+    }
+
     default:
       return true;
     }
@@ -4043,16 +4049,18 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
   }
 
   void visitProtocolCompositionType(ProtocolCompositionType *T) {
-    Printer << tok::kw_protocol << "<";
-    bool First = true;
-    for (auto Proto : T->getProtocols()) {
-      if (First)
-        First = false;
-      else
-        Printer << ", ";
-      visit(Proto);
+    if (T->getProtocols().empty()) {
+      Printer << "Any";
+    } else {
+      bool First = true;
+      for (auto Proto : T->getProtocols()) {
+        if (First)
+          First = false;
+        else
+          Printer << " & ";
+        visit(Proto);
+      }
     }
-    Printer << ">";
   }
 
   void visitLValueType(LValueType *T) {

lib/AST/ArchetypeBuilder.cpp

@@ -826,23 +826,17 @@ void ArchetypeBuilder::PotentialArchetype::dump(llvm::raw_ostream &Out,
   if (!ConformsTo.empty()) {
     Out << " : ";
 
-    if (ConformsTo.size() != 1)
-      Out << "protocol<";
-
     bool First = true;
     for (const auto &ProtoAndSource : ConformsTo) {
       if (First)
         First = false;
       else
-        Out << ", ";
+        Out << " & ";
 
       Out << ProtoAndSource.first->getName().str() << " [";
       ProtoAndSource.second.dump(Out, SrcMgr);
       Out << "]";
     }
-
-    if (ConformsTo.size() != 1)
-      Out << ">";
   }
 
   if (Representative != this) {

lib/AST/TypeRepr.cpp

@@ -434,16 +434,18 @@ ProtocolCompositionTypeRepr::create(ASTContext &C,
 
 void ProtocolCompositionTypeRepr::printImpl(ASTPrinter &Printer,
                                             const PrintOptions &Opts) const {
-  Printer << "protocol<";
-  bool First = true;
-  for (auto Proto : Protocols) {
-    if (First)
-      First = false;
-    else
-      Printer << ", ";
-    printTypeRepr(Proto, Printer, Opts);
+  if (Protocols.empty()) {
+    Printer << "Any";
+  } else {
+    bool First = true;
+    for (auto Proto : Protocols) {
+      if (First)
+        First = false;
+      else
+        Printer << " & ";
+      printTypeRepr(Proto, Printer, Opts);
+    }
   }
-  Printer << ">";
 }
 
 void MetatypeTypeRepr::printImpl(ASTPrinter &Printer,

lib/Basic/Demangle.cpp

@@ -3465,12 +3465,10 @@ void NodePrinter::print(NodePointer pointer, bool asContext, bool suppressType)
     NodePointer type_list = pointer->getChild(0);
     if (!type_list)
       return;
-    bool needs_proto_marker = (type_list->getNumChildren() != 1);
-    if (needs_proto_marker)
-      Printer << "protocol<";
-    printChildren(type_list, ", ");
-    if (needs_proto_marker)
-      Printer << ">";
+    if (type_list->getNumChildren() == 0)
+      Printer << "Any";
+    else
+      printChildren(type_list, " & ");
     return;
   }
   case Node::Kind::Archetype: {

lib/IDE/TypeReconstruction.cpp

@@ -1890,7 +1890,7 @@ static void VisitNodeProtocolList(
     nodes.push_back(cur_node->getFirstChild());
     VisitNode(ast, nodes, protocol_types_result, generic_context);
     if (protocol_types_result._error
-            .empty() /* cannot check for empty type list as protocol<> is allowed */) {
+            .empty() /* cannot check for empty type list as Any is allowed */) {
       if (ast) {
         result._types.push_back(
             ProtocolCompositionType::get(*ast, protocol_types_result._types));

lib/IRGen/GenExistential.cpp

@@ -258,7 +258,8 @@ class ExistentialTypeInfoBase : public Base,
 
 /// A TypeInfo implementation for existential types, i.e., types like:
 ///   Printable
-///   protocol<Printable, Serializable>
+///   Printable & Serializable
+///   Any
 /// with the semantic translation:
 ///   \exists t : Printable . t
 /// t here is an ArchetypeType.

lib/IRGen/GenType.cpp

@@ -1657,16 +1657,18 @@ llvm::StructType *IRGenModule::createNominalType(CanType type) {
 llvm::StructType *
 IRGenModule::createNominalType(ProtocolCompositionType *type) {
   llvm::SmallString<32> typeName;
-
+  
   SmallVector<ProtocolDecl *, 4> protocols;
   type->getAnyExistentialTypeProtocols(protocols);
-
-  typeName.append("protocol<");
-  for (unsigned i = 0, e = protocols.size(); i != e; ++i) {
-    if (i) typeName.push_back(',');
-    LinkEntity::forNonFunction(protocols[i]).mangle(typeName);
+  
+  if (protocols.empty()) {
+    typeName.append("swift.Any");
+  } else {
+    for (unsigned i = 0, e = protocols.size(); i != e; ++i) {
+      if (i) typeName.push_back('&');
+      LinkEntity::forNonFunction(protocols[i]).mangle(typeName);
+    }
   }
-  typeName.push_back('>');
   return llvm::StructType::create(getLLVMContext(), typeName.str());
 }
 

stdlib/public/runtime/Casting.cpp

@@ -123,34 +123,33 @@ static const char *_getProtocolName(const ProtocolDescriptor *protocol) {
 }
 
 static void _buildExistentialTypeName(const ProtocolDescriptorList *protocols,
+                                      TypeSyntaxLevel level,
                                       bool qualified,
                                       std::string &result) {
   auto options = Demangle::DemangleOptions();
   options.QualifyEntities = qualified;
   options.DisplayDebuggerGeneratedModule = false;
-
+  
   // If there's only one protocol, the existential type name is the protocol
-  // name.
+  // name. If there are 0 protocols it is 'Any'
   auto descriptors = protocols->getProtocols();
+  auto numProtocols = protocols->NumProtocols;
 
-  if (protocols->NumProtocols == 1) {
-    auto name = _getProtocolName(descriptors[0]);
-    result += Demangle::demangleTypeAsString(name,
-                                             strlen(name),
-                                             options);
-    return;
-  }
-  
-  result += "protocol<";
-  for (unsigned i = 0, e = protocols->NumProtocols; i < e; ++i) {
-    if (i > 0)
-      result += ", ";
-    auto name = _getProtocolName(descriptors[i]);
-    result += Demangle::demangleTypeAsString(name,
-                                             strlen(name),
-                                             options);
+  if (numProtocols == 0) {
+    result += "Any";
+  } else {
+    // compositions of more than 1 protocol need parens in .Type contexts
+    bool needsParens = level >= TypeSyntaxLevel::TypeSimple && numProtocols != 1;
+    if (needsParens) result += "(";
+    for (unsigned i = 0, e = numProtocols; i < e; ++i) {
+      if (i) result += " & ";
+      auto name = _getProtocolName(descriptors[i]);
+      result += Demangle::demangleTypeAsString(name,
+                                               strlen(name),
+                                               options);
+    }
+    if (needsParens) result += ")";
   }
-  result += ">";
 }
 
 static void _buildFunctionTypeName(const FunctionTypeMetadata *func,
@@ -233,7 +232,7 @@ static void _buildNameForMetadata(const Metadata *type,
   }
   case MetadataKind::Existential: {
     auto exis = static_cast<const ExistentialTypeMetadata *>(type);
-    _buildExistentialTypeName(&exis->Protocols, qualified, result);
+    _buildExistentialTypeName(&exis->Protocols, level, qualified, result);
     return;
   }
   case MetadataKind::ExistentialMetatype: {

stdlib/public/runtime/Reflection.mm

@@ -47,7 +47,7 @@ - (id)debugQuickLookObject;
 
 namespace {
 
-/// The layout of protocol<>.
+/// The layout of Any.
 using Any = OpaqueExistentialContainer;
 
 // Swift assumes Any is returned in memory.