[interop][SwiftToCxxToSwift] hide reverse interop module namespaces from forward interop

Author: hyp

lib/ClangImporter/ImportDecl.cpp

@@ -1089,6 +1089,9 @@ namespace {
 
     Decl *VisitNamespaceDecl(const clang::NamespaceDecl *decl) {
       DeclContext *dc = nullptr;
+      // Do not import namespace declarations marked as 'swift_private'.
+      if (decl->hasAttr<clang::SwiftPrivateAttr>())
+        return nullptr;
       // If this is a top-level namespace, don't put it in the module we're
       // importing, put it in the "__ObjC" module that is implicitly imported.
       if (!decl->getParent()->isNamespace())

lib/PrintAsClang/ClangSyntaxPrinter.cpp

@@ -50,13 +50,13 @@ bool ClangSyntaxPrinter::isClangKeyword(Identifier name) {
   return ClangSyntaxPrinter::isClangKeyword(name.str());
 }
 
-void ClangSyntaxPrinter::printIdentifier(StringRef name) {
+void ClangSyntaxPrinter::printIdentifier(StringRef name) const {
   os << name;
   if (ClangSyntaxPrinter::isClangKeyword(name))
     os << '_';
 }
 
-void ClangSyntaxPrinter::printBaseName(const ValueDecl *decl) {
+void ClangSyntaxPrinter::printBaseName(const ValueDecl *decl) const {
   assert(decl->getName().isSimpleName());
   printIdentifier(cxx_translation::getNameForCxx(decl));
 }
@@ -136,12 +136,23 @@ void ClangSyntaxPrinter::printNominalTypeQualifier(
   os << "::";
 }
 
+void ClangSyntaxPrinter::printModuleNamespaceStart(
+    const ModuleDecl &moduleContext) const {
+  os << "namespace ";
+  printBaseName(&moduleContext);
+  os << " __attribute__((swift_private))";
+  os << " {\n";
+}
+
 /// Print a C++ namespace declaration with the give name and body.
 void ClangSyntaxPrinter::printNamespace(
     llvm::function_ref<void(raw_ostream &OS)> namePrinter,
-    llvm::function_ref<void(raw_ostream &OS)> bodyPrinter) const {
+    llvm::function_ref<void(raw_ostream &OS)> bodyPrinter,
+    NamespaceTrivia trivia) const {
   os << "namespace ";
   namePrinter(os);
+  if (trivia == NamespaceTrivia::AttributeSwiftPrivate)
+    os << " __attribute__((swift_private))";
   os << " {\n\n";
   bodyPrinter(os);
   os << "\n} // namespace ";
@@ -150,9 +161,9 @@ void ClangSyntaxPrinter::printNamespace(
 }
 
 void ClangSyntaxPrinter::printNamespace(
-    StringRef name,
-    llvm::function_ref<void(raw_ostream &OS)> bodyPrinter) const {
-  printNamespace([&](raw_ostream &os) { os << name; }, bodyPrinter);
+    StringRef name, llvm::function_ref<void(raw_ostream &OS)> bodyPrinter,
+    NamespaceTrivia trivia) const {
+  printNamespace([&](raw_ostream &os) { os << name; }, bodyPrinter, trivia);
 }
 
 void ClangSyntaxPrinter::printExternC(

lib/PrintAsClang/ClangSyntaxPrinter.h

@@ -50,10 +50,10 @@ class ClangSyntaxPrinter {
 
   /// Print a given identifier. If the identifer conflicts with a keyword, add a
   /// trailing underscore.
-  void printIdentifier(StringRef name);
+  void printIdentifier(StringRef name) const;
 
   /// Print the base name of the given declaration.
-  void printBaseName(const ValueDecl *decl);
+  void printBaseName(const ValueDecl *decl) const;
 
   /// Print the C-style prefix for the given module name, that's used for
   /// C type names inside the module.
@@ -118,14 +118,18 @@ class ClangSyntaxPrinter {
   void printNominalTypeQualifier(const NominalTypeDecl *typeDecl,
                                  const ModuleDecl *moduleContext);
 
+  enum class NamespaceTrivia { None, AttributeSwiftPrivate };
+
+  void printModuleNamespaceStart(const ModuleDecl &moduleContext) const;
+
   /// Print a C++ namespace declaration with the give name and body.
-  void
-  printNamespace(llvm::function_ref<void(raw_ostream &OS)> namePrinter,
-                 llvm::function_ref<void(raw_ostream &OS)> bodyPrinter) const;
+  void printNamespace(llvm::function_ref<void(raw_ostream &OS)> namePrinter,
+                      llvm::function_ref<void(raw_ostream &OS)> bodyPrinter,
+                      NamespaceTrivia trivia = NamespaceTrivia::None) const;
 
-  void
-  printNamespace(StringRef name,
-                 llvm::function_ref<void(raw_ostream &OS)> bodyPrinter) const;
+  void printNamespace(StringRef name,
+                      llvm::function_ref<void(raw_ostream &OS)> bodyPrinter,
+                      NamespaceTrivia trivia = NamespaceTrivia::None) const;
 
   /// Print an extern C block with given body.
   void

lib/PrintAsClang/ModuleContentsWriter.cpp

@@ -783,6 +783,7 @@ EmittedClangHeaderDependencyInfo swift::printModuleContentsAsCxx(
     os << "#ifdef __cplusplus\n";
     os << "namespace ";
     M.ValueDecl::getName().print(os);
+    os << " __attribute__((swift_private))";
     os << " {\n";
     os << "namespace " << cxx_synthesis::getCxxImplNamespaceName() << " {\n";
     os << "extern \"C\" {\n";
@@ -800,6 +801,7 @@ EmittedClangHeaderDependencyInfo swift::printModuleContentsAsCxx(
   // Construct a C++ namespace for the module.
   ClangSyntaxPrinter(os).printNamespace(
       [&](raw_ostream &os) { M.ValueDecl::getName().print(os); },
-      [&](raw_ostream &os) { os << moduleOS.str(); });
+      [&](raw_ostream &os) { os << moduleOS.str(); },
+      ClangSyntaxPrinter::NamespaceTrivia::AttributeSwiftPrivate);
   return info;
 }

lib/PrintAsClang/PrintClangValueType.cpp

@@ -496,9 +496,8 @@ void ClangValueTypePrinter::printTypePrecedingGenericTraits(
   }
   os << "#pragma clang diagnostic pop\n";
   os << "} // namespace swift\n";
-  os << "\nnamespace ";
-  printer.printBaseName(moduleContext);
-  os << " {\n";
+  os << "\n";
+  printer.printModuleNamespaceStart(*moduleContext);
 }
 
 void ClangValueTypePrinter::printTypeGenericTraits(
@@ -592,7 +591,6 @@ void ClangValueTypePrinter::printTypeGenericTraits(
   os << "} // namespace\n";
   os << "#pragma clang diagnostic pop\n";
   os << "} // namespace swift\n";
-  os << "\nnamespace ";
-  printer.printBaseName(moduleContext);
-  os << " {\n";
+  os << "\n";
+  printer.printModuleNamespaceStart(*moduleContext);
 }

test/Interop/SwiftToCxx/class/swift-actor-in-cxx.swift

@@ -30,7 +30,7 @@ public final actor ActorWithField {
   }
 }
 
-// CHECK: namespace Actor {
+// CHECK: namespace Actor __attribute__((swift_private)) {
 // CHECK: SWIFT_EXTERN void * _Nonnull $s5Actor0A9WithFieldCACycfC(SWIFT_CONTEXT void * _Nonnull _self) SWIFT_NOEXCEPT SWIFT_CALL; // init()
 // CHECK: SWIFT_EXTERN void $s5Actor0A9WithFieldC6methodyyF(SWIFT_CONTEXT void * _Nonnull _self) SWIFT_NOEXCEPT SWIFT_CALL; // method()
 

test/Interop/SwiftToCxx/class/swift-class-in-cxx.swift

@@ -21,14 +21,14 @@ public final class ClassWithIntField {
   }
 }
 
-// CHECK: namespace Class {
+// CHECK: namespace Class __attribute__((swift_private)) {
 
 // CHECK: SWIFT_EXTERN void * _Nonnull $s5Class011passThroughA12WithIntFieldyAA0adeF0CADF(void * _Nonnull x) SWIFT_NOEXCEPT SWIFT_CALL; // passThroughClassWithIntField(_:)
 // CHECK-NEXT: SWIFT_EXTERN void * _Nonnull $s5Class06returnA12WithIntFieldAA0acdE0CyF(void) SWIFT_NOEXCEPT SWIFT_CALL; // returnClassWithIntField()
 // CHECK-NEXT: SWIFT_EXTERN void $s5Class04takeA12WithIntFieldyyAA0acdE0CF(void * _Nonnull x) SWIFT_NOEXCEPT SWIFT_CALL; // takeClassWithIntField(_:)
 // CHECK-NEXT: SWIFT_EXTERN void $s5Class04takeA17WithIntFieldInoutyyAA0acdE0CzF(void * _Nonnull * _Nonnull x) SWIFT_NOEXCEPT SWIFT_CALL; // takeClassWithIntFieldInout(_:)
 
-// CHECK: namespace Class {
+// CHECK: namespace Class __attribute__((swift_private)) {
 
 // CHECK: class ClassWithIntField;
 // CHECK-NEXT: } // end namespace
@@ -43,7 +43,7 @@ public final class ClassWithIntField {
 // CHECK-NEXT: } // namespace swift
 
 // CHECK: namespace
-// CHECK-SAME: Class {
+// CHECK-SAME: Class __attribute__((swift_private)) {
 
 // CHECK: namespace
 // CHECK-SAME: _impl {
@@ -92,7 +92,7 @@ public final class ClassWithIntField {
 // CHECK-NEXT: #pragma clang diagnostic pop
 // CHECK-NEXT: } // namespace swift
 // CHECK-EMPTY:
-// CHECK-NEXT: namespace Class {
+// CHECK-NEXT: namespace Class __attribute__((swift_private)) {
 
 // CHECK: inline ClassWithIntField passThroughClassWithIntField(const ClassWithIntField& x) noexcept SWIFT_WARN_UNUSED_RESULT {
 // CHECK-NEXT:  return _impl::_impl_ClassWithIntField::makeRetained(_impl::$s5Class011passThroughA12WithIntFieldyAA0adeF0CADF(::swift::_impl::_impl_RefCountedClass::getOpaquePointer(x)));

test/Interop/SwiftToCxx/core/gen-header-for-module.swift

@@ -22,5 +22,5 @@ public func reprintedInImportedModule() -> Int {
     return 42
 }
 
-// CHECK: namespace Core {
+// CHECK: namespace Core __attribute__((swift_private)) {
 // CHECK: swift::Int reprintedInImportedModule() noexcept SWIFT_WARN_UNUSED_RESULT {

test/Interop/SwiftToCxx/enums/swift-enum-implementation.swift

@@ -166,7 +166,7 @@ public struct S {
 // CHECK-NEXT: #endif
 // CHECK-NEXT:     vwTable->initializeWithTake(destStorage, srcStorage, metadata._0);
 // CHECK-NEXT:   }
-// CHECK:      namespace Enums {
+// CHECK:      namespace Enums __attribute__((swift_private)) {
 // CHECK:        inline E E::_impl_x::operator()(double val) const {
 // CHECK-NEXT:     auto result = E::_make();
 // CHECK-NEXT:     memcpy(result._getOpaquePointer(), &val, sizeof(val));

test/Interop/SwiftToCxx/enums/zero-sized-enum-in-cxx.swift

@@ -5,7 +5,7 @@
 public enum EmptyEnum {}
 public enum SingleCaseEnum { case first }
 
-// CHECK: namespace Enums {
+// CHECK: namespace Enums __attribute__((swift_private)) {
 // CHECK-NOT: class EmptyEnum final {
 // CHECK-NOT: class SingleCaseEnum final {
 // CHECK: } // namespace Enums

test/Interop/SwiftToCxx/functions/cdecl.swift

@@ -4,7 +4,7 @@
 
 // RUN: %check-interop-cxx-header-in-clang(%t/cdecl.h)
 
-// CHECK-LABEL: namespace CdeclFunctions {
+// CHECK-LABEL: namespace CdeclFunctions __attribute__((swift_private)) {
 
 // CHECK: namespace _impl {
 // CHECK: SWIFT_EXTERN int cfuncPassTwo(int x, int y) SWIFT_NOEXCEPT;

test/Interop/SwiftToCxx/functions/function-availability.swift

@@ -4,7 +4,7 @@
 
 // RUN: %check-interop-cxx-header-in-clang(%t/functions.h)
 
-// CHECK-LABEL: namespace Functions {
+// CHECK-LABEL: namespace Functions __attribute__((swift_private)) {
 
 // CHECK-LABEL: namespace _impl {
 

test/Interop/SwiftToCxx/functions/swift-functions-errors.swift

@@ -4,7 +4,7 @@
 
 // RUN: %check-interop-cxx-header-in-clang(%t/functions.h)
 
-// CHECK-LABEL: namespace Functions {
+// CHECK-LABEL: namespace Functions __attribute__((swift_private)) {
 
 // CHECK-LABEL: namespace _impl {
 

test/Interop/SwiftToCxx/functions/swift-functions.swift

@@ -4,7 +4,7 @@
 
 // RUN: %check-interop-cxx-header-in-clang(%t/functions.h)
 
-// CHECK-LABEL: namespace Functions {
+// CHECK-LABEL: namespace Functions __attribute__((swift_private)) {
 
 // CHECK-LABEL: namespace _impl {
 

test/Interop/SwiftToCxx/functions/swift-no-expose-unsupported-alwaysEmitInClient-func.swift

@@ -6,7 +6,7 @@
 
 // CHECK-NOT: SWIFT_EXTERN bool $s9Functions24alwaysEmitIntoClientFuncyS2bF(bool x) SWIFT_NOEXCEPT SWIFT_CALL; // alwaysEmitIntoClientFunc(_:)
 
-// CHECK:       namespace Functions {
+// CHECK:       namespace Functions __attribute__((swift_private)) {
 // CHECK-EMPTY:
 // CHECK-EMPTY:
 // CHECK-EMPTY:

test/Interop/SwiftToCxx/functions/swift-no-expose-unsupported-async-func.swift

@@ -6,7 +6,7 @@
 
 // CHECK-NOT: SWIFT_EXTERN double $s9Functions9asyncFuncyS2dYaF(double x) SWIFT_NOEXCEPT SWIFT_CALL; // asyncFunc(_:)
 
-// CHECK:       namespace Functions {
+// CHECK:       namespace Functions __attribute__((swift_private)) {
 // CHECK-EMPTY:
 // CHECK-EMPTY:
 // CHECK-NEXT:  } // namespace Functions

test/Interop/SwiftToCxx/generics/generic-type-traits-fwd.swift

@@ -39,7 +39,7 @@ public struct LaterGeneric<T> {
 // CHECK: class ComesFirstEnum final {
 // CHECK: LaterGeneric<ComesFirstEnum> returnsLaterOpt() const;
 
-// CHECK: namespace Generics {
+// CHECK: namespace Generics __attribute__((swift_private)) {
 // CHECK-EMPTY:
 // CHECK-NEXT:  namespace _impl {
 // CHECK-EMPTY:

test/Interop/SwiftToCxx/module/module-to-namespace.swift

@@ -4,5 +4,5 @@
 
 // RUN: %check-interop-cxx-header-in-clang(%t/empty.h)
 
-// CHECK-LABEL: namespace Test {
+// CHECK-LABEL: namespace Test __attribute__((swift_private)) {
 // CHECK:       } // namespace Test

test/Interop/SwiftToCxx/stdlib/stdlib-dep-inline-in-cxx.swift

@@ -14,5 +14,5 @@ public func test() -> String {
     return ""
 }
 
-// CHECK: namespace Swift {
+// CHECK: namespace Swift __attribute__((swift_private)) {
 // CHECK: class String final {

test/Interop/SwiftToCxx/stdlib/swift-stdlib-in-cxx.swift

@@ -6,7 +6,7 @@
 
 // FIXME: remove need for -Wno-shadow
 
-// CHECK: namespace Swift {
+// CHECK: namespace Swift __attribute__((swift_private)) {
 
 // CHECK: template<class T_0_0>
 // CHECK-NEXT: #ifdef __cpp_concepts

test/Interop/SwiftToCxx/structs/resilient-struct-in-cxx.swift

@@ -92,7 +92,7 @@ public struct FirstSmallStruct {
 // CHECK-NEXT: #pragma clang diagnostic pop
 // CHECK-NEXT: } // namespace swift
 // CHECK-EMPTY:
-// CHECK-NEXT: namespace Structs {
+// CHECK-NEXT: namespace Structs __attribute__((swift_private)) {
 
 @frozen public struct FrozenStruct {
     private let storedInt: Int32

test/Interop/SwiftToCxx/structs/swift-struct-in-cxx.swift

@@ -4,10 +4,10 @@
 
 // RUN: %check-interop-cxx-header-in-clang(%t/structs.h -Wno-unused-private-field -Wno-unused-function)
 
-// CHECK: namespace Structs {
+// CHECK: namespace Structs __attribute__((swift_private)) {
 // CHECK: namespace _impl {
 
-// CHECK: namespace Structs {
+// CHECK: namespace Structs __attribute__((swift_private)) {
 
 // CHECK: class StructWithIntField;
 // CHECK-NEXT: } // end namespace
@@ -20,7 +20,7 @@
 // CHECK-NEXT: #pragma clang diagnostic pop
 // CHECK-NEXT: } // namespace swift
 
-// CHECK: namespace Structs {
+// CHECK: namespace Structs __attribute__((swift_private)) {
 
 // CHECK:      namespace _impl {
 // CHECK-EMPTY:
@@ -95,7 +95,7 @@
 // CHECK-NEXT: #pragma clang diagnostic pop
 // CHECK-NEXT: } // namespace swift
 // CHECK-EMPTY:
-// CHECK-NEXT: namespace Structs {
+// CHECK-NEXT: namespace Structs __attribute__((swift_private)) {
 
 public struct StructWithIntField {
   let field: Int64

test/Interop/SwiftToCxx/structs/zero-sized-struct-in-cxx.swift

@@ -2,7 +2,7 @@
 // RUN: %target-swift-frontend %s -typecheck -module-name Structs -clang-header-expose-decls=all-public -emit-clang-header-path %t/structs.h
 // RUN: %FileCheck %s < %t/structs.h
 
-// CHECK: namespace Structs {
+// CHECK: namespace Structs __attribute__((swift_private)) {
 
 // CHECK-NOT: class ZeroSizedStruct final {
 

test/Interop/SwiftToCxxToSwift/hide-swift-module-namespace-in-swift.swift

@@ -0,0 +1,34 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+// RUN: touch %t/swiftMod.h
+// RUN: %target-swift-frontend -typecheck %t/swiftMod.swift -typecheck -module-name SwiftMod -emit-clang-header-path %t/swiftMod.h -I %t -enable-experimental-cxx-interop
+
+// RUN: %FileCheck %s < %t/swiftMod.h
+
+// RUN: %target-swift-frontend -typecheck %t/swiftMod.swift -typecheck -module-name SwiftMod -emit-clang-header-path %t/swiftMod2.h -I %t -enable-experimental-cxx-interop
+
+// RUN: %check-interop-cxx-header-in-clang(%t/swiftMod2.h -Wno-error)
+
+//--- header.h
+#include "swiftMod.h"
+
+//--- module.modulemap
+module SwiftToCxxTest {
+    header "header.h"
+    requires cplusplus
+}
+
+//--- swiftMod.swift
+import SwiftToCxxTest
+
+@_expose(Cxx)
+public func testFunction() -> String {
+    let arr = Swift.Array<Int>()
+    let rng = Swift.SystemRandomNumberGenerator()
+    return ""
+}
+
+// CHECK: namespace Swift __attribute__((swift_private)) {
+// CHECK: namespace SwiftMod __attribute__((swift_private)) {
+// CHECK-NOT: namespace Swift {

test/PrintAsCxx/empty.swift

@@ -103,7 +103,7 @@
 // CHECK:       } // namespace swift
 // CHECK-EMPTY:
 // CHECK-NEXT:  #endif
-// CHECK:       namespace empty {
+// CHECK:       namespace empty __attribute__((swift_private)) {
 // CHECK:       } // namespace empty
 // CHECK:       #endif