[interop][SwiftToCxx] support copy-assignment operation for Swift value types and prohibit move assignment explicitly

Fixes #66324

Note: move semantics for Swift value types are not yet supported in C++

Author: hyp

lib/PrintAsClang/PrintClangValueType.cpp

@@ -288,6 +288,7 @@ void ClangValueTypePrinter::printValueTypeDecl(
   os << "    vwTable->destroy(_getOpaquePointer(), metadata._0);\n";
   os << "  }\n";
 
+  // copy constructor.
   os << "  ";
   printer.printInlineForThunk();
   printer.printBaseName(typeDecl);
@@ -306,6 +307,28 @@ void ClangValueTypePrinter::printValueTypeDecl(
         "*>(other._getOpaquePointer()), metadata._0);\n";
   os << "  }\n";
 
+  // copy assignment.
+  os << "  ";
+  printer.printInlineForThunk();
+  printer.printBaseName(typeDecl);
+  os << " &operator =(const ";
+  printer.printBaseName(typeDecl);
+  os << " &other) noexcept {\n";
+  ClangValueTypePrinter::printValueWitnessTableAccessAsVariable(
+      os, typeMetadataFuncName, typeMetadataFuncGenericParams);
+  os << "    vwTable->assignWithCopy(_getOpaquePointer(), const_cast<char "
+        "*>(other._getOpaquePointer()), metadata._0);\n";
+  os << "  return *this;\n";
+  os << "  }\n";
+
+  // FIXME: implement the move assignment.
+  os << "  ";
+  printer.printInlineForThunk();
+  printer.printBaseName(typeDecl);
+  os << " &operator =(";
+  printer.printBaseName(typeDecl);
+  os << " &&other) = delete;\n";
+
   // FIXME: implement the move constructor.
   os << "  [[noreturn]] ";
   // NOTE: Do not apply attribute((used))

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

@@ -72,6 +72,9 @@
 // CHECK:  }
 // CHECK-NEXT:  SWIFT_INLINE_THUNK String(const String &other) noexcept {
 // CHECK:  }
+// CHECK-NEXT:  SWIFT_INLINE_THUNK String &operator =(const String &other) noexcept {
+// CHECK:  }
+// CHECK-NEXT:  SWIFT_INLINE_THUNK String &operator =(String &&other) = delete;
 // CHECK-NEXT:  SWIFT_INLINE_PRIVATE_HELPER String(String &&) noexcept {
 // CHECK: }
 // CHECK-NEXT:  static SWIFT_INLINE_THUNK String init() SWIFT_SYMBOL({{.*}});

test/Interop/SwiftToCxx/structs/struct-move-semantics-in-cxx.cpp

@@ -9,6 +9,10 @@
 
 // LINK: fatalError_Cxx_move_of_Swift_value_type_not_supported_yet
 
+// Compile should fail by default when move assignment is attempted in C++:
+
+// RUN: not %target-interop-build-clangxx -c %s -I %t -o %t/swift-structs-execution.o -DMOVE_ASSIGN 2>&1 | %FileCheck --check-prefix=MOVEASSIGN %s
+
 // Fallback to abort at runtime:
 
 // RUN: %target-interop-build-clangxx -c %s -I %t -o %t/swift-structs-execution.o -DLINKS
@@ -34,7 +38,13 @@ int main() {
   using namespace Structs;
 
   auto x = returnNewStructSeveralI64(42);
+#ifdef MOVE_ASSIGN
+  auto y = returnNewStructSeveralI64(24);
+  x = std::move(y);
+// MOVEASSIGN: deleted operator '='
+#else
   StructSeveralI64 x2 = std::move(x);
+#endif
   return 0;
 }
 

test/Interop/SwiftToCxx/structs/struct-with-refcounted-member-execution.cpp

@@ -44,5 +44,19 @@ int main() {
 // CHECK-NEXT: destroy RefCountedClass
 // CHECK-NEXT: destroy RefCountedClass
 // CHECK-NEXT: breakpoint 3
+
+  {
+    StructWithRefcountedMember value = returnNewStructWithRefcountedMember();
+    StructWithRefcountedMember value2 = returnNewStructWithRefcountedMember();
+    value = value2;
+    printBreak(4);
+  }
+  printBreak(5);
+// CHECK-NEXT: create RefCountedClass
+// CHECK-NEXT: create RefCountedClass
+// CHECK-NEXT: destroy RefCountedClass
+// CHECK-NEXT: breakpoint 4
+// CHECK-NEXT: destroy RefCountedClass
+// CHECK-NEXT: breakpoint 5
   return 0;
 }

test/Interop/SwiftToCxx/structs/struct-with-refcounted-member.swift

@@ -47,6 +47,18 @@ public func printBreak(_ x: Int) {
 // CHECK-NEXT: #endif
 // CHECK-NEXT:     vwTable->initializeWithCopy(_getOpaquePointer(), const_cast<char *>(other._getOpaquePointer()), metadata._0);
 // CHECK-NEXT:   }
+// CHECK-NEXT:   SWIFT_INLINE_THUNK StructWithRefcountedMember &operator =(const StructWithRefcountedMember &other) noexcept {
+// CHECK-NEXT:     auto metadata = _impl::$s7Structs26StructWithRefcountedMemberVMa(0);
+// CHECK-NEXT:     auto *vwTableAddr = reinterpret_cast<swift::_impl::ValueWitnessTable **>(metadata._0) - 1;
+// CHECK-NEXT:   #ifdef __arm64e__
+// CHECK-NEXT:     auto *vwTable = reinterpret_cast<swift::_impl::ValueWitnessTable *>(ptrauth_auth_data(reinterpret_cast<void *>(*vwTableAddr), ptrauth_key_process_independent_data, ptrauth_blend_discriminator(vwTableAddr, 11839)));
+// CHECK-NEXT:   #else
+// CHECK-NEXT:     auto *vwTable = *vwTableAddr;
+// CHECK-NEXT:   #endif
+// CHECK-NEXT:     vwTable->assignWithCopy(_getOpaquePointer(), const_cast<char *>(other._getOpaquePointer()), metadata._0);
+// CHECK-NEXT:   return *this;
+// CHECK-NEXT:   }
+// CHECK-NEXT:   SWIFT_INLINE_THUNK StructWithRefcountedMember &operator =(StructWithRefcountedMember &&other) = delete;
 // CHECK-NEXT:   SWIFT_INLINE_PRIVATE_HELPER StructWithRefcountedMember(StructWithRefcountedMember &&) noexcept {
 // CHECK-NEXT:  swift::_impl::_fatalError_Cxx_move_of_Swift_value_type_not_supported_yet();
 // CHECK-NEXT:  swift::_impl::_swift_stdlib_reportFatalError("swift", 5, "C++ does not support moving a Swift value yet", 45, 0);

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

@@ -38,6 +38,18 @@
 // CHECK:        }
 // CHECK-NEXT:   SWIFT_INLINE_THUNK StructWithIntField(const StructWithIntField &other) noexcept {
 // CHECK:        }
+// CHECK:        SWIFT_INLINE_THUNK StructWithIntField &operator =(const StructWithIntField &other) noexcept {
+// CHECK-NEXT:     auto metadata = _impl::$s7Structs18StructWithIntFieldVMa(0);
+// CHECK-NEXT:     auto *vwTableAddr = reinterpret_cast<swift::_impl::ValueWitnessTable **>(metadata._0) - 1;
+// CHECK-NEXT:   #ifdef __arm64e__
+// CHECK-NEXT:     auto *vwTable = reinterpret_cast<swift::_impl::ValueWitnessTable *>(ptrauth_auth_data(reinterpret_cast<void *>(*vwTableAddr), ptrauth_key_process_independent_data, ptrauth_blend_discriminator(vwTableAddr, 11839)));
+// CHECK-NEXT:   #else
+// CHECK-NEXT:     auto *vwTable = *vwTableAddr;
+// CHECK-NEXT:   #endif
+// CHECK-NEXT:     vwTable->assignWithCopy(_getOpaquePointer(), const_cast<char *>(other._getOpaquePointer()), metadata._0);
+// CHECK-NEXT:   return *this;
+// CHECK-NEXT:  }
+// CHECK-NEXT:   SWIFT_INLINE_THUNK StructWithIntField &operator =(StructWithIntField &&other) = delete;
 // CHECK-NEXT:   noreturn]] SWIFT_INLINE_PRIVATE_HELPER StructWithIntField(StructWithIntField &&) noexcept {
 // CHECK-NEXT:   swift::_impl::_fatalError_Cxx_move_of_Swift_value_type_not_supported_yet();
 // CHECK-NEXT:   swift::_impl::_swift_stdlib_reportFatalError("swift", 5, "C++ does not support moving a Swift value yet", 45, 0);