[cxx-interop] Support nested structs

lib/AST/SwiftNameTranslation.cpp

@@ -244,8 +244,8 @@ swift::cxx_translation::getDeclRepresentation(const ValueDecl *VD) {
         return {Unsupported, UnrepresentableGeneric};
       genericSignature = typeDecl->getGenericSignature();
     }
-    // Nested types are not yet supported.
-    if (!typeDecl->hasClangNode() &&
+    // Nested classes are not yet supported.
+    if (isa<ClassDecl>(VD) && !typeDecl->hasClangNode() &&
         isa_and_nonnull<NominalTypeDecl>(
             typeDecl->getDeclContext()->getAsDecl()))
       return {Unsupported, UnrepresentableNested};

lib/PrintAsClang/ClangSyntaxPrinter.cpp

@@ -20,8 +20,10 @@
 #include "swift/AST/TypeCheckRequests.h"
 #include "swift/Basic/Assertions.h"
 #include "clang/AST/ASTContext.h"
+#include "clang/AST/Decl.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/NestedNameSpecifier.h"
+#include "llvm/Support/Casting.h"
 
 using namespace swift;
 using namespace cxx_synthesis;
@@ -79,7 +81,6 @@ void ClangSyntaxPrinter::printModuleNamespaceQualifiersIfNeeded(
 
 bool ClangSyntaxPrinter::printNominalTypeOutsideMemberDeclTemplateSpecifiers(
     const NominalTypeDecl *typeDecl) {
-  // FIXME: Full qualifiers for nested types?
   if (!typeDecl->isGeneric())
     return true;
   printGenericSignature(
@@ -126,6 +127,26 @@ void ClangSyntaxPrinter::printClangTypeReference(const clang::Decl *typeDecl) {
   }
 }
 
+bool ClangSyntaxPrinter::printNestedTypeNamespaceQualifiers(
+    const ValueDecl *D) const {
+  bool first = true;
+  while (auto parent = dyn_cast_or_null<NominalTypeDecl>(
+             D->getDeclContext()->getAsDecl())) {
+    // C++ namespaces are imported as enums.
+    if (parent->hasClangNode() &&
+        isa<clang::NamespaceDecl>(parent->getClangNode().getAsDecl()))
+      break;
+    if (!first)
+      os << "::";
+    first = false;
+    os << "__";
+    printBaseName(parent);
+    os << "Nested";
+    D = parent;
+  }
+  return first;
+}
+
 void ClangSyntaxPrinter::printNominalTypeReference(
     const NominalTypeDecl *typeDecl, const ModuleDecl *moduleContext) {
   if (typeDecl->hasClangNode()) {
@@ -134,7 +155,8 @@ void ClangSyntaxPrinter::printNominalTypeReference(
   }
   printModuleNamespaceQualifiersIfNeeded(typeDecl->getModuleContext(),
                                          moduleContext);
-  // FIXME: Full qualifiers for nested types?
+  if (!printNestedTypeNamespaceQualifiers(typeDecl))
+    os << "::";
   ClangSyntaxPrinter(os).printBaseName(typeDecl);
   if (typeDecl->isGeneric())
     printGenericSignatureParams(
@@ -180,6 +202,18 @@ void ClangSyntaxPrinter::printNamespace(
   printNamespace([&](raw_ostream &os) { os << name; }, bodyPrinter, trivia);
 }
 
+void ClangSyntaxPrinter::printParentNamespaceForNestedTypes(
+    const ValueDecl *D, llvm::function_ref<void(raw_ostream &OS)> bodyPrinter,
+    NamespaceTrivia trivia) const {
+  if (!isa_and_nonnull<NominalTypeDecl>(D->getDeclContext()->getAsDecl())) {
+    bodyPrinter(os);
+    return;
+  }
+  printNamespace(
+      [=](raw_ostream &os) { printNestedTypeNamespaceQualifiers(D); },
+      bodyPrinter, trivia);
+}
+
 void ClangSyntaxPrinter::printExternC(
     llvm::function_ref<void(raw_ostream &OS)> bodyPrinter) const {
   os << "#ifdef __cplusplus\n";
@@ -383,7 +417,8 @@ void ClangSyntaxPrinter::printPrimaryCxxTypeName(
     const NominalTypeDecl *type, const ModuleDecl *moduleContext) {
   printModuleNamespaceQualifiersIfNeeded(type->getModuleContext(),
                                          moduleContext);
-  // FIXME: Print class qualifiers for nested class references.
+  if (!printNestedTypeNamespaceQualifiers(type))
+    os << "::";
   printBaseName(type);
 }
 

lib/PrintAsClang/ClangSyntaxPrinter.h

@@ -94,6 +94,9 @@ class ClangSyntaxPrinter {
   bool printNominalTypeOutsideMemberDeclInnerStaticAssert(
       const NominalTypeDecl *typeDecl);
 
+  // Returns true when no qualifiers were printed.
+  bool printNestedTypeNamespaceQualifiers(const ValueDecl *D) const;
+
   /// Print out the C++ class access qualifier for the given Swift  type
   /// declaration.
   ///
@@ -135,6 +138,13 @@ class ClangSyntaxPrinter {
                       llvm::function_ref<void(raw_ostream &OS)> bodyPrinter,
                       NamespaceTrivia trivia = NamespaceTrivia::None) const;
 
+  /// Prints the C++ namespaces of the outer types for a nested type.
+  /// E.g., for struct Foo { struct Bar {...} } it will print
+  /// namespace __FooNested { ..body.. } // namespace __FooNested
+  void printParentNamespaceForNestedTypes(
+      const ValueDecl *D, llvm::function_ref<void(raw_ostream &OS)> bodyPrinter,
+      NamespaceTrivia trivia = NamespaceTrivia::None) const;
+
   /// Print an extern C block with given body.
   void
   printExternC(llvm::function_ref<void(raw_ostream &OS)> bodyPrinter) const;

lib/PrintAsClang/DeclAndTypePrinter.cpp

@@ -12,6 +12,7 @@
 
 #include "DeclAndTypePrinter.h"
 #include "ClangSyntaxPrinter.h"
+#include "OutputLanguageMode.h"
 #include "PrimitiveTypeMapping.h"
 #include "PrintClangClassType.h"
 #include "PrintClangFunction.h"
@@ -46,6 +47,7 @@
 #include "clang/AST/DeclObjC.h"
 #include "clang/Basic/CharInfo.h"
 #include "clang/Basic/SourceManager.h"
+#include "llvm/Support/Casting.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace swift;
@@ -234,14 +236,33 @@ class DeclAndTypePrinter::Implementation
     os << ">";
   }
 
+  void printUsingForNestedType(const NominalTypeDecl *TD,
+                               const ModuleDecl *moduleContext) {
+    if (TD->isImplicit() || TD->isSynthesized())
+      return;
+    os << "  using ";
+    ClangSyntaxPrinter(os).printBaseName(TD);
+    os << "=";
+    ClangSyntaxPrinter(os).printNominalTypeReference(TD, moduleContext);
+    os << ";\n";
+  }
+
   /// Prints the members of a class, extension, or protocol.
   template <bool AllowDelayed = false, typename R>
   void printMembers(R &&members) {
     CxxEmissionScopeRAII cxxScopeRAII(owningPrinter);
-    // FIXME: Actually track emitted members in nested
-    // lexical scopes.
-    // FIXME: Emit unavailable C++ decls for not emitted
-    // nested members.
+    // Using statements for nested types.
+    if (outputLang == OutputLanguageMode::Cxx) {
+      for (const Decl *member : members) {
+        if (member->getModuleContext()->isStdlibModule())
+          break;
+        // TODO: support nested classes.
+        if (isa<ClassDecl>(member))
+          continue;
+        if (const auto *TD = dyn_cast<NominalTypeDecl>(member))
+          printUsingForNestedType(TD, TD->getModuleContext());
+      }
+    }
     bool protocolMembersOptional = false;
     for (const Decl *member : members) {
       auto VD = dyn_cast<ValueDecl>(member);
@@ -2796,14 +2817,16 @@ static bool isAsyncAlternativeOfOtherDecl(const ValueDecl *VD) {
   return false;
 }
 
-static bool isStringNestedType(const ValueDecl *VD, StringRef Typename) {
+namespace swift {
+bool isStringNestedType(const ValueDecl *VD, StringRef Typename) {
   auto ctx = VD->getDeclContext();
   return VD->hasName() && VD->getName().isSimpleName() &&
          VD->getBaseIdentifier().str() == Typename &&
          isa<ExtensionDecl>(ctx->getAsDecl()) &&
          cast<ExtensionDecl>(ctx->getAsDecl())->getExtendedNominal() ==
              VD->getASTContext().getStringDecl();
 }
+} // namespace swift
 
 static bool hasExposeAttr(const ValueDecl *VD) {
   if (isa<NominalTypeDecl>(VD) && VD->getModuleContext()->isStdlibModule()) {

lib/PrintAsClang/DeclAndTypePrinter.h

@@ -148,6 +148,8 @@ class DeclAndTypePrinter {
   getObjectTypeAndOptionality(const ValueDecl *D, Type ty);
 };
 
+bool isStringNestedType(const ValueDecl *VD, StringRef Typename);
+
 } // end namespace swift
 
 #endif

lib/PrintAsClang/ModuleContentsWriter.cpp

@@ -31,6 +31,7 @@
 #include "swift/Basic/Assertions.h"
 #include "swift/Basic/SourceManager.h"
 #include "swift/ClangImporter/ClangImporter.h"
+#include "swift/SIL/SILInstruction.h"
 #include "swift/Strings.h"
 
 #include "clang/AST/Decl.h"
@@ -218,7 +219,10 @@ class ModuleWriter {
     return state.first == EmissionState::Defined;
   }
 
-  bool require(const TypeDecl *D) {
+  bool require(const TypeDecl *D) { return requireTypes(D, declsToWrite); }
+
+  template <typename T>
+  bool requireTypes(const TypeDecl *D, T &types) {
     if (addImport(D)) {
       seenTypes[D] = { EmissionState::Defined, true };
       return true;
@@ -229,7 +233,7 @@ class ModuleWriter {
     case EmissionState::NotYetDefined:
     case EmissionState::DefinitionRequested:
       state.first = EmissionState::DefinitionRequested;
-      declsToWrite.push_back(D);
+      types.push_back(D);
       return false;
     case EmissionState::Defined:
       return true;
@@ -364,23 +368,31 @@ class ModuleWriter {
     }
 
     bool hadAnyDelayedMembers = false;
-    SmallVector<ValueDecl *, 4> nestedTypes;
+    SmallVector<const ValueDecl *, 4> nestedTypes;
     for (auto member : members) {
       PrettyStackTraceDecl loopEntry("printing for member", member);
       auto VD = dyn_cast<ValueDecl>(member);
       if (!VD || !printer.shouldInclude(VD))
         continue;
 
       // Catch nested types and emit their definitions /after/ this class.
-      if (isa<TypeDecl>(VD)) {
-        // Don't emit nested types that are just implicitly @objc.
-        // You should have to opt into this, since they are even less
-        // namespaced than usual.
-        if (std::any_of(VD->getAttrs().begin(), VD->getAttrs().end(),
-                        [](const DeclAttribute *attr) {
-                          return isa<ObjCAttr>(attr) && !attr->isImplicit();
-                        })) {
-          nestedTypes.push_back(VD);
+      if (const auto *TD = dyn_cast<TypeDecl>(VD)) {
+        if (outputLangMode == OutputLanguageMode::Cxx) {
+          if (!isa<TypeAliasDecl>(TD) && !isStringNestedType(VD, "UTF8View") &&
+              !isStringNestedType(VD, "Index")) {
+            forwardDeclareType(TD);
+            requireTypes(TD, nestedTypes);
+          }
+        } else {
+          // Don't emit nested types that are just implicitly @objc.
+          // You should have to opt into this, since they are even less
+          // namespaced than usual.
+          if (std::any_of(VD->getAttrs().begin(), VD->getAttrs().end(),
+                          [](const DeclAttribute *attr) {
+                            return isa<ObjCAttr>(attr) && !attr->isImplicit();
+                          })) {
+            nestedTypes.push_back(VD);
+          }
         }
         continue;
       }
@@ -1060,11 +1072,14 @@ EmittedClangHeaderDependencyInfo swift::printModuleContentsAsCxx(
     os << "}\n";
   }
 
+  os << "#pragma clang diagnostic push\n";
+  os << "#pragma clang diagnostic ignored \"-Wreserved-identifier\"\n";
   // Construct a C++ namespace for the module.
   ClangSyntaxPrinter(os).printNamespace(
       [&](raw_ostream &os) { ClangSyntaxPrinter(os).printBaseName(&M); },
       [&](raw_ostream &os) { os << moduleOS.str(); },
       ClangSyntaxPrinter::NamespaceTrivia::AttributeSwiftPrivate, &M);
+  os << "#pragma clang diagnostic pop\n";
 
   if (M.isStdlibModule()) {
     os << "#pragma clang diagnostic pop\n";