Merge pull request swiftlang#83065 from Xazax-hun/guard-more-objc-on-6.2

[6.2][cxx-interop] Types exposed from ObjC modules should be behind a macro

Author: Xazax-hun

include/swift/AST/SwiftNameTranslation.h

@@ -13,6 +13,7 @@
 #ifndef SWIFT_NAME_TRANSLATION_H
 #define SWIFT_NAME_TRANSLATION_H
 
+#include "swift/AST/ASTContext.h"
 #include "swift/AST/AttrKind.h"
 #include "swift/AST/Decl.h"
 #include "swift/AST/DiagnosticEngine.h"
@@ -112,6 +113,9 @@ inline bool isExposableToCxx(
   return !getDeclRepresentation(VD, isZeroSized).isUnsupported();
 }
 
+bool isObjCxxOnly(const ValueDecl *VD);
+bool isObjCxxOnly(const clang::Decl *D, const ASTContext &ctx);
+
 /// Returns true if the given value decl D is visible to C++ of its
 /// own accord (i.e. without considering its context)
 bool isVisibleToCxx(const ValueDecl *VD, AccessLevel minRequiredAccess,

include/swift/Basic/LangOptions.h

@@ -632,6 +632,10 @@ namespace swift {
     /// All block list configuration files to be honored in this compilation.
     std::vector<std::string> BlocklistConfigFilePaths;
 
+    /// List of top level modules to be considered as if they had require ObjC
+    /// in their module map.
+    llvm::SmallVector<StringRef> ModulesRequiringObjC;
+
     /// Whether to ignore checks that a module is resilient during
     /// type-checking, SIL verification, and IR emission,
     bool BypassResilienceChecks = false;

lib/AST/SwiftNameTranslation.cpp

@@ -28,6 +28,8 @@
 #include "swift/Basic/StringExtras.h"
 
 #include "clang/AST/DeclObjC.h"
+#include "clang/Basic/Module.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
 #include <optional>
 
@@ -238,6 +240,51 @@ swift::cxx_translation::getNameForCxx(const ValueDecl *VD,
   return VD->getBaseIdentifier().str();
 }
 
+namespace {
+struct ObjCTypeWalker : TypeWalker {
+  bool hadObjCType = false;
+  const ASTContext &ctx;
+  ObjCTypeWalker(const ASTContext &ctx) : ctx(ctx) {}
+  Action walkToTypePre(Type ty) override {
+    if (auto *nominal = ty->getNominalOrBoundGenericNominal()) {
+      if (auto clangDecl = nominal->getClangDecl()) {
+        if (cxx_translation::isObjCxxOnly(clangDecl, ctx)) {
+          hadObjCType = true;
+          return Action::Stop;
+        }
+      }
+    }
+    return Action::Continue;
+  }
+};
+} // namespace
+
+bool swift::cxx_translation::isObjCxxOnly(const ValueDecl *VD) {
+  ObjCTypeWalker walker{VD->getASTContext()};
+  VD->getInterfaceType().walk(walker);
+  return walker.hadObjCType;
+}
+
+bool swift::cxx_translation::isObjCxxOnly(const clang::Decl *D,
+                                          const ASTContext &ctx) {
+  // By default, we import all modules in Obj-C++ mode, so there is no robust
+  // way to tell if something is coming from an Obj-C module. Use the
+  // requirements and the language options to check if we should actually
+  // consider the module to have ObjC constructs.
+  const auto &langOpts = D->getASTContext().getLangOpts();
+  auto clangModule = D->getOwningModule()->getTopLevelModule();
+  bool requiresObjC = false;
+  for (auto req : clangModule->Requirements)
+    if (req.RequiredState && req.FeatureName == "objc")
+      requiresObjC = true;
+  return langOpts.ObjC &&
+         (requiresObjC ||
+          llvm::any_of(ctx.LangOpts.ModulesRequiringObjC,
+                       [clangModule](StringRef moduleName) {
+                         return clangModule->getFullModuleName() == moduleName;
+                       }));
+}
+
 swift::cxx_translation::DeclRepresentation
 swift::cxx_translation::getDeclRepresentation(
     const ValueDecl *VD,
@@ -324,6 +371,9 @@ swift::cxx_translation::getDeclRepresentation(
     return {Unsupported, UnrepresentableGenericRequirements};
   }
 
+  if (isObjCxxOnly(VD))
+    return {ObjCxxOnly, std::nullopt};
+
   return {Representable, std::nullopt};
 }
 

lib/Frontend/CompilerInvocation.cpp

@@ -847,7 +847,8 @@ static bool ParseEnabledFeatureArgs(LangOptions &Opts, ArgList &Args,
     // Collect some special case pseudo-features which should be processed
     // separately.
     if (argValue.starts_with("StrictConcurrency") ||
-        argValue.starts_with("AvailabilityMacro=")) {
+        argValue.starts_with("AvailabilityMacro=") ||
+        argValue.starts_with("RequiresObjC=")) {
       if (isEnableFeatureFlag)
         psuedoFeatures.push_back(argValue);
       continue;
@@ -974,6 +975,11 @@ static bool ParseEnabledFeatureArgs(LangOptions &Opts, ArgList &Args,
       Opts.AvailabilityMacros.push_back(availability.str());
       continue;
     }
+
+    if (featureName->starts_with("RequiresObjC")) {
+      auto modules = featureName->split("=").second;
+      modules.split(Opts.ModulesRequiringObjC, ",");
+    }
   }
 
   // Map historical flags over to experimental features. We do this for all

lib/PrintAsClang/PrintClangFunction.cpp

@@ -812,7 +812,8 @@ ClangRepresentation DeclAndTypeClangFunctionPrinter::printFunctionSignature(
     ClangSyntaxPrinter(FD->getASTContext(), functionSignatureOS).printInlineForThunk();
 
   ClangRepresentation resultingRepresentation =
-      ClangRepresentation::representable;
+      cxx_translation::isObjCxxOnly(FD) ? ClangRepresentation::objcxxonly
+                                        : ClangRepresentation::representable;
 
   // Print out the return type.
   if (FD->hasThrows() && outputLang == OutputLanguageMode::Cxx)

lib/PrintAsClang/PrintClangValueType.cpp

@@ -16,12 +16,14 @@
 #include "OutputLanguageMode.h"
 #include "PrimitiveTypeMapping.h"
 #include "SwiftToClangInteropContext.h"
+#include "swift/AST/ASTContext.h"
 #include "swift/AST/Decl.h"
 #include "swift/AST/SwiftNameTranslation.h"
 #include "swift/AST/Type.h"
 #include "swift/ClangImporter/ClangImporter.h"
 #include "swift/IRGen/IRABIDetailsProvider.h"
 #include "swift/IRGen/Linking.h"
+#include "clang/Basic/Module.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/raw_ostream.h"
 
@@ -642,20 +644,28 @@ void ClangValueTypePrinter::printTypeGenericTraits(
     });
   }
 
+  bool objCxxOnly = false;
+  if (const auto *clangDecl = typeDecl->getClangDecl()) {
+    if (cxx_translation::isObjCxxOnly(clangDecl, typeDecl->getASTContext()))
+      objCxxOnly = true;
+  }
+
   // FIXME: avoid popping out of the module's namespace here.
   os << "} // end namespace \n\n";
   os << "namespace swift SWIFT_PRIVATE_ATTR {\n";
   auto classDecl = dyn_cast<ClassDecl>(typeDecl);
   bool addPointer =
       typeDecl->isObjC() || (classDecl && classDecl->isForeignReferenceType());
 
+  if (objCxxOnly)
+    os << "#if defined(__OBJC__)\n";
   os << "#pragma clang diagnostic push\n";
   os << "#pragma clang diagnostic ignored \"-Wc++17-extensions\"\n";
-  if (typeDecl->hasClangNode()) {
+  if (const auto *clangDecl = typeDecl->getClangDecl()) {
     // FIXME: share the code.
     os << "template<>\n";
     os << "inline const constexpr bool isUsableInGenericContext<";
-    printer.printClangTypeReference(typeDecl->getClangDecl());
+    printer.printClangTypeReference(clangDecl);
     if (addPointer)
       os << "*";
     os << "> = true;\n";
@@ -665,8 +675,8 @@ void ClangValueTypePrinter::printTypeGenericTraits(
   os << "struct";
   declAndTypePrinter.printAvailability(os, typeDecl);
   os << " TypeMetadataTrait<";
-  if (typeDecl->hasClangNode()) {
-    printer.printClangTypeReference(typeDecl->getClangDecl());
+  if (const auto *clangDecl = typeDecl->getClangDecl()) {
+    printer.printClangTypeReference(clangDecl);
     if (addPointer)
       os << "*";
   } else {
@@ -746,6 +756,8 @@ void ClangValueTypePrinter::printTypeGenericTraits(
   }
   os << "} // namespace\n";
   os << "#pragma clang diagnostic pop\n";
+  if (objCxxOnly)
+    os << "#endif // #if defined(__OBJC__)\n";
   os << "} // namespace swift\n";
   os << "\n";
   printer.printModuleNamespaceStart(*moduleContext);

test/Interop/SwiftToCxx/stdlib/foundation-type-not-exposed-by-default-to-cxx.swift

@@ -1,8 +1,10 @@
 // RUN: %empty-directory(%t)
 
-// RUN: %target-swift-frontend %s -module-name UseFoundation -enable-experimental-cxx-interop -typecheck -verify -emit-clang-header-path %t/UseFoundation.h
+// RUN: %target-swift-frontend %s -module-name UseFoundation -enable-experimental-cxx-interop -typecheck -verify -emit-clang-header-path %t/UseFoundation.h -enable-experimental-feature RequiresObjC=CoreGraphics,Foundation
 // RUN: %FileCheck %s < %t/UseFoundation.h
 
+// RUN: %check-interop-cxx-header-in-clang(%t/UseFoundation.h -DSWIFT_CXX_INTEROP_HIDE_STL_OVERLAY)
+
 // REQUIRES: objc_interop
 
 import Foundation
@@ -12,4 +14,8 @@ public enum UseFoundationEnum {
     case B
 }
 
+public func f() -> Decimal {
+    Decimal()
+}
+
 // CHECK: class UseFoundationEnum { } SWIFT_UNAVAILABLE_MSG("Swift enum 'UseFoundationEnum' cannot be represented in C++");

test/Misc/verify-swift-feature-testing.test-sh

@@ -21,6 +21,8 @@ EXCEPTIONAL_FILES = [
     pathlib.Path("test/ModuleInterface/swift-export-as.swift"),
     # Uses the pseudo-feature AvailabilityMacro=
     pathlib.Path("test/Availability/availability_define.swift"),
+    # Uses the pseudo-feature RequiresObjC=
+    pathlib.Path("test/Interop/SwiftToCxx/stdlib/foundation-type-not-exposed-by-default-to-cxx.swift"),
     # Tests behavior when you try to use a feature without enabling it
     pathlib.Path("test/attr/feature_requirement.swift"),
     # Tests completion with features both enabled and disabled