[interop] Prohibit use of C++ APIs in public interfaces that opt-in i…

include/swift/AST/DiagnosticsSema.def

@@ -3187,7 +3187,8 @@ ERROR(decl_from_hidden_module,none,
       "it is an SPI imported from %3|"
       "it is SPI|"
       "%3 was imported for SPI only|"
-      "%3 was not imported by this file}4",
+      "%3 was not imported by this file|"
+      "C++ types from imported module %3 do not support library evolution}4",
       (DescriptiveDeclKind, DeclName, unsigned, Identifier, unsigned))
 WARNING(decl_from_hidden_module_warn,none,
       "cannot use %0 %1 %select{here|as property wrapper here|"
@@ -3208,7 +3209,8 @@ ERROR(typealias_desugars_to_type_from_hidden_module,none,
       "it is an SPI imported from %4|"
       "<<ERROR>>|"
       "%4 was imported for SPI only|"
-      "%4 was not imported by this file}5",
+      "%4 was not imported by this file|"
+      "C++ types from imported module %4 do not support library evolution}5",
       (DeclName, StringRef, StringRef, unsigned, Identifier, unsigned))
 ERROR(conformance_from_implementation_only_module,none,
       "cannot use conformance of %0 to %1 %select{here|as property wrapper here|"
@@ -3219,7 +3221,8 @@ ERROR(conformance_from_implementation_only_module,none,
       "the conformance is declared as SPI in %3|"
       "the conformance is declared as SPI|"
       "%3 was imported for SPI only|"
-      "%3 was not imported by this file}4",
+      "%3 was not imported by this file|"
+      "C++ types from imported module %3 do not support library evolution}4",
       (Type, Identifier, unsigned, Identifier, unsigned))
 NOTE(assoc_conformance_from_implementation_only_module,none,
      "in associated type %0 (inferred as %1)", (Type, Type))
@@ -6290,7 +6293,8 @@ ERROR(inlinable_decl_ref_from_hidden_module,
       "it is an SPI imported from %3|"
       "it is SPI|"
       "%3 was imported for SPI only|"
-      "%3 was not imported by this file}4",
+      "%3 was not imported by this file|"
+      "C++ APIs from imported module %3 do not support library evolution}4",
       (DescriptiveDeclKind, DeclName, unsigned, Identifier, unsigned))
 
 WARNING(inlinable_decl_ref_from_hidden_module_warn,
@@ -6306,7 +6310,8 @@ ERROR(inlinable_typealias_desugars_to_type_from_hidden_module,
       "it is an SPI imported from %4|"
       "<<ERROR>>|"
       "%4 was imported for SPI only|"
-      "%4 was not imported by this file}5",
+      "%4 was not imported by this file|"
+      "C++ types from imported module %4 do not support library evolution}5",
       (DeclName, StringRef, StringRef, unsigned, Identifier, unsigned))
 
 NOTE(missing_import_inserted,

lib/Sema/TypeCheckAccess.cpp

@@ -26,6 +26,7 @@
 #include "swift/AST/Pattern.h"
 #include "swift/AST/ParameterList.h"
 #include "swift/AST/TypeCheckRequests.h"
+#include "clang/AST/DeclObjC.h"
 
 using namespace swift;
 
@@ -1788,6 +1789,66 @@ class UsableFromInlineChecker : public AccessControlCheckerBase,
     }
   }
 };
+
+bool isFragileClangType(clang::QualType type) {
+  if (type.isNull())
+    return true;
+  auto underlyingTypePtr = type->getUnqualifiedDesugaredType();
+  // Objective-C types are compatible with library
+  // evolution.
+  if (underlyingTypePtr->isObjCObjectPointerType())
+    return false;
+  // Builtin clang types are compatible with library evolution.
+  if (underlyingTypePtr->isBuiltinType())
+    return false;
+  // Pointers to non-fragile types are non-fragile.
+  if (underlyingTypePtr->isPointerType())
+    return isFragileClangType(underlyingTypePtr->getPointeeType());
+  return true;
+}
+
+bool isFragileClangNode(const ClangNode &node) {
+  auto *decl = node.getAsDecl();
+  if (!decl)
+    return false;
+  // Namespaces by themselves don't impact ABI.
+  if (isa<clang::NamespaceDecl>(decl))
+    return false;
+  // Objective-C type declarations are compatible with library evolution.
+  if (isa<clang::ObjCContainerDecl>(decl))
+    return false;
+  if (auto *fd = dyn_cast<clang::FunctionDecl>(decl)) {
+    if (!isa<clang::CXXMethodDecl>(decl) &&
+        !isFragileClangType(fd->getDeclaredReturnType())) {
+      for (const auto *param : fd->parameters()) {
+        if (isFragileClangType(param->getType()))
+          return true;
+      }
+      // A global function whose return and parameter types are compatible with
+      // library evolution is compatible with library evolution.
+      return false;
+    }
+  }
+  if (auto *md = dyn_cast<clang::ObjCMethodDecl>(decl)) {
+    if (!isFragileClangType(md->getReturnType())) {
+      for (const auto *param : md->parameters()) {
+        if (isFragileClangType(param->getType()))
+          return true;
+      }
+      // An Objective-C method whose return and parameter types are compatible
+      // with library evolution is compatible with library evolution.
+      return false;
+    }
+  }
+  // An Objective-C property whose can be compatible
+  // with library evolution if its type is compatible.
+  if (auto *pd = dyn_cast<clang::ObjCPropertyDecl>(decl))
+    return isFragileClangType(pd->getType());
+  if (auto *typedefDecl = dyn_cast<clang::TypedefNameDecl>(decl))
+    return isFragileClangType(typedefDecl->getUnderlyingType());
+  return true;
+}
+
 } // end anonymous namespace
 
 /// Returns the kind of origin, implementation-only import or SPI declaration,
@@ -1894,6 +1955,14 @@ swift::getDisallowedOriginKind(const Decl *decl,
       DisallowedOriginKind::SPIImported;
   }
 
+  // C++ APIs do not support library evolution.
+  if (SF->getASTContext().LangOpts.EnableCXXInterop && where.getDeclContext() &&
+      where.getDeclContext()->getAsDecl() &&
+      where.getDeclContext()->getAsDecl()->getModuleContext()->isResilient() &&
+      decl->hasClangNode() && !decl->getModuleContext()->isSwiftShimsModule() &&
+      isFragileClangNode(decl->getClangNode()))
+    return DisallowedOriginKind::FragileCxxAPI;
+
   return DisallowedOriginKind::None;
 }
 

lib/Sema/TypeCheckAccess.h

@@ -46,6 +46,7 @@ enum class DisallowedOriginKind : uint8_t {
   SPILocal,
   SPIOnly,
   MissingImport,
+  FragileCxxAPI,
   None
 };
 

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -643,6 +643,7 @@ endfunction()
 #     [IS_STDLIB]
 #     [IS_STDLIB_CORE]
 #     [IS_SDK_OVERLAY]
+#     [IS_FRAGILE]
 #     INSTALL_IN_COMPONENT comp
 #     MACCATALYST_BUILD_FLAVOR flavor
 #     source1 [source2 source3 ...])
@@ -709,6 +710,11 @@ endfunction()
 #
 # MACCATALYST_BUILD_FLAVOR
 #   Possible values are 'ios-like', 'macos-like', 'zippered', 'unzippered-twin'
+
+# IS_FRAGILE
+#   Disable library evolution even
+#   if this library is part of the SDK.
+
 #
 # source1 ...
 #   Sources to add into this library
@@ -723,7 +729,8 @@ function(add_swift_target_library_single target name)
         SHARED
         STATIC
         NO_LINK_NAME
-        INSTALL_WITH_SHARED)
+        INSTALL_WITH_SHARED
+        IS_FRAGILE)
   set(SWIFTLIB_SINGLE_single_parameter_options
         ARCHITECTURE
         DEPLOYMENT_VERSION_IOS
@@ -932,6 +939,7 @@ function(add_swift_target_library_single target name)
       ${SWIFTLIB_SINGLE_IS_STDLIB_keyword}
       ${SWIFTLIB_SINGLE_IS_STDLIB_CORE_keyword}
       ${SWIFTLIB_SINGLE_IS_SDK_OVERLAY_keyword}
+      ${SWIFTLIB_SINGLE_IS_FRAGILE_keyword}
       ${embed_bitcode_arg}
       ${SWIFTLIB_SINGLE_STATIC_keyword}
       ${SWIFTLIB_SINGLE_NO_LINK_NAME_keyword}

stdlib/cmake/modules/SwiftSource.cmake

@@ -49,7 +49,7 @@ function(handle_swift_sources
     dependency_sibgen_target_out_var_name
     sourcesvar externalvar name)
   cmake_parse_arguments(SWIFTSOURCES
-      "IS_MAIN;IS_STDLIB;IS_STDLIB_CORE;IS_SDK_OVERLAY;EMBED_BITCODE;STATIC;NO_LINK_NAME"
+      "IS_MAIN;IS_STDLIB;IS_STDLIB_CORE;IS_SDK_OVERLAY;EMBED_BITCODE;STATIC;NO_LINK_NAME;IS_FRAGILE"
       "SDK;ARCHITECTURE;INSTALL_IN_COMPONENT;MACCATALYST_BUILD_FLAVOR;BOOTSTRAPPING"
       "DEPENDS;COMPILE_FLAGS;MODULE_NAME;ENABLE_LTO"
       ${ARGN})
@@ -64,6 +64,7 @@ function(handle_swift_sources
   translate_flag(${SWIFTSOURCES_STATIC} "STATIC"
                  STATIC_arg)
   translate_flag(${SWIFTSOURCES_NO_LINK_NAME} "NO_LINK_NAME" NO_LINK_NAME_arg)
+  translate_flag(${SWIFTSOURCES_IS_FRAGILE} "IS_FRAGILE" IS_FRAGILE_arg)
   if(DEFINED SWIFTSOURCES_BOOTSTRAPPING)
     set(BOOTSTRAPPING_arg "BOOTSTRAPPING" ${SWIFTSOURCES_BOOTSTRAPPING})
   endif()
@@ -152,6 +153,7 @@ function(handle_swift_sources
         ${EMBED_BITCODE_arg}
         ${STATIC_arg}
         ${BOOTSTRAPPING_arg}
+        ${IS_FRAGILE_arg}
         INSTALL_IN_COMPONENT "${SWIFTSOURCES_INSTALL_IN_COMPONENT}"
         MACCATALYST_BUILD_FLAVOR "${SWIFTSOURCES_MACCATALYST_BUILD_FLAVOR}")
     set("${dependency_target_out_var_name}" "${dependency_target}" PARENT_SCOPE)
@@ -376,7 +378,7 @@ function(_compile_swift_files
     dependency_sib_target_out_var_name dependency_sibopt_target_out_var_name
     dependency_sibgen_target_out_var_name)
   cmake_parse_arguments(SWIFTFILE
-    "IS_MAIN;IS_STDLIB;IS_STDLIB_CORE;IS_SDK_OVERLAY;EMBED_BITCODE;STATIC"
+    "IS_MAIN;IS_STDLIB;IS_STDLIB_CORE;IS_SDK_OVERLAY;EMBED_BITCODE;STATIC;IS_FRAGILE"
     "OUTPUT;MODULE_NAME;INSTALL_IN_COMPONENT;MACCATALYST_BUILD_FLAVOR;BOOTSTRAPPING"
     "SOURCES;FLAGS;DEPENDS;SDK;ARCHITECTURE;OPT_FLAGS;MODULE_DIR"
     ${ARGN})
@@ -487,7 +489,7 @@ function(_compile_swift_files
   endif()
 
   # The standard library and overlays are built resiliently when SWIFT_STDLIB_STABLE_ABI=On.
-  if(SWIFTFILE_IS_STDLIB AND SWIFT_STDLIB_STABLE_ABI)
+  if(SWIFTFILE_IS_STDLIB AND NOT SWIFTFILE_IS_FRAGILE AND SWIFT_STDLIB_STABLE_ABI)
     list(APPEND swift_flags "-enable-library-evolution")
     list(APPEND swift_flags "-library-level" "api")
     list(APPEND swift_flags "-Xfrontend" "-require-explicit-availability=ignore")

stdlib/public/Cxx/std/CMakeLists.txt

@@ -127,7 +127,9 @@ add_dependencies(sdk-overlay libstdcxx-modulemap)
 #
 # C++ Standard Library Overlay.
 #
-add_swift_target_library(swiftCxxStdlib STATIC NO_LINK_NAME IS_STDLIB IS_SWIFT_ONLY
+# The overlay is fragile (i.e. it does not use library evolution)
+# as it's not ABI stable.
+add_swift_target_library(swiftCxxStdlib STATIC NO_LINK_NAME IS_STDLIB IS_SWIFT_ONLY IS_FRAGILE
     std.swift
     String.swift
 

test/Interop/Cxx/library-evolution/allow-objc-in-cxx-mode-in-evolving-libraries.swift

@@ -0,0 +1,90 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+// RUN: %target-swift-frontend %t/test.swift -I %t/Inputs -typecheck -enable-library-evolution -enable-experimental-cxx-interop -verify
+
+// REQUIRES: objc_interop
+
+//--- Inputs/module.modulemap
+module ObjCxxModule {
+    header "header.h"
+    requires cplusplus
+}
+
+//--- Inputs/header.h
+
+#import <Foundation/Foundation.h>
+
+class CxxStruct {
+public:
+    int x; int y;
+
+    void method() const;
+};
+
+@interface ObjCClass: NSObject
+
+- (void)myTestMethod;
+- (int *)returnsIntPtr;
+
+- (CxxStruct)testMethodReturnsCxxStruct;
+- (void)testMethodTakesCxxStructPtr: (CxxStruct * _Nullable) ptr;
++ (ObjCClass * _Nonnull)getInstance;
+
+@property int intProp;
+@property(copy) ObjCClass * _Nonnull objcClassProp;
+@property CxxStruct * structPtrProp;
+
+@end
+
+using ObjCClassTypealias = ObjCClass * _Nonnull;
+
+@protocol ObjCProto
+
+- (void)testProto;
+
+@end
+
+using QualIDTypeAlias = id<ObjCProto>;
+
+using BuiltinIntTypealis = int;
+
+//--- test.swift
+
+import ObjCxxModule
+
+// ok
+public func usesObjCClass() -> ObjCClass {
+    return ObjCClass.getInstance()
+}
+
+public func usesObjCClassTypealias(_ x: ObjCClassTypealias) {
+}
+
+public func usesObjCProto(_ x: ObjCProto) {
+}
+
+public func usesQualIDTypeAlias(_ x: QualIDTypeAlias) {
+}
+
+public func usesBuiltinIntTypealis() -> BuiltinIntTypealis {
+    return 21
+}
+
+@inlinable
+public func publicFuncPublicBody() {
+    let i = ObjCClass.getInstance()
+    i.myTestMethod()
+    i.returnsIntPtr()
+    let _ = i.intProp
+    let _ = i.objcClassProp
+    // expected-error@+1 {{instance method 'testMethodReturnsCxxStruct()' cannot be used in an '@inlinable' function because C++ APIs from imported module 'ObjCxxModule' do not support library evolution}}
+    i.testMethodReturnsCxxStruct()
+    // expected-error@+1 {{instance method 'testMethodTakesCxxStructPtr' cannot be used in an '@inlinable' function because C++ APIs from imported module 'ObjCxxModule' do not support library evolution}}
+    i.testMethodTakesCxxStructPtr(nil)
+    // expected-error@+1 {{property 'structPtrProp' cannot be used in an '@inlinable' function because C++ APIs from imported module 'ObjCxxModule' do not support library evolution}}
+    let _ = i.structPtrProp
+}
+
+// expected-error@+1 {{cannot use struct 'CxxStruct' here; C++ types from imported module 'ObjCxxModule' do not support library evolution}}
+public func usesCxxStruct(_ x: CxxStruct) {
+}