[interop][SwiftToCxx] emit copy constructor that calls value witness initWithCopy function for Swift structs

Author: hyp

lib/PrintAsClang/PrintClangValueType.cpp

@@ -126,7 +126,15 @@ void ClangValueTypePrinter::printStructDecl(const StructDecl *SD) {
   printer.printBaseName(SD);
   os << "(const ";
   printer.printBaseName(SD);
-  os << " &) = default;\n";
+  os << " &other) {\n";
+  os << "    auto metadata = " << cxx_synthesis::getCxxImplNamespaceName()
+     << "::" << typeMetadataFuncName << "(0);\n";
+  os << "    auto *vwTable = "
+        "*(reinterpret_cast<swift::_impl::ValueWitnessTable **>(metadata._0) - "
+        "1);\n";
+  os << "    vwTable->initializeWithCopy(_getOpaquePointer(), const_cast<char "
+        "*>(other._getOpaquePointer()), metadata._0);\n";
+  os << "  }\n";
 
   // FIXME: the move constructor should be hidden somehow.
   os << "  inline ";

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

@@ -20,7 +20,29 @@ int main() {
   {
     StructWithRefcountedMember value = returnNewStructWithRefcountedMember();
   }
+  printBreak(1);
 // CHECK:      create RefCountedClass
 // CHECK-NEXT: destroy RefCountedClass
+// CHECK-NEXT: breakpoint 1
+
+  {
+    StructWithRefcountedMember value = returnNewStructWithRefcountedMember();
+    StructWithRefcountedMember copyValue(value);
+  }
+  printBreak(2);
+// CHECK-NEXT: create RefCountedClass
+// CHECK-NEXT: destroy RefCountedClass
+// CHECK-NEXT: breakpoint 2
+
+  {
+    StructWithRefcountedMember value = returnNewStructWithRefcountedMember();
+    StructWithRefcountedMember value2(returnNewStructWithRefcountedMember());
+  }
+  printBreak(3);
+// CHECK-NEXT: create RefCountedClass
+// CHECK-NEXT: create RefCountedClass
+// CHECK-NEXT: destroy RefCountedClass
+// CHECK-NEXT: destroy RefCountedClass
+// CHECK-NEXT: breakpoint 3
   return 0;
 }

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

@@ -21,13 +21,21 @@ public func returnNewStructWithRefcountedMember() -> StructWithRefcountedMember
     return StructWithRefcountedMember(x: RefCountedClass())
 }
 
+public func printBreak(_ x: Int) {
+    print("breakpoint \(x)")
+}
+
 // CHECK:      class StructWithRefcountedMember final {
 // CHECK-NEXT: public:
 // CHECK-NEXT:   inline ~StructWithRefcountedMember() {
 // CHECK-NEXT:     auto metadata = _impl::$s7Structs26StructWithRefcountedMemberVMa(0);
 // CHECK-NEXT:     auto *vwTable = *(reinterpret_cast<swift::_impl::ValueWitnessTable **>(metadata._0) - 1);
 // CHECK-NEXT:     vwTable->destroy(_getOpaquePointer(), metadata._0);
 // CHECK-NEXT:   }
-// CHECK-NEXT:   inline StructWithRefcountedMember(const StructWithRefcountedMember &) = default;
+// CHECK-NEXT:   inline StructWithRefcountedMember(const StructWithRefcountedMember &other) {
+// CHECK-NEXT:     auto metadata = _impl::$s7Structs26StructWithRefcountedMemberVMa(0);
+// CHECK-NEXT:     auto *vwTable = *(reinterpret_cast<swift::_impl::ValueWitnessTable **>(metadata._0) - 1);
+// CHECK-NEXT:     vwTable->initializeWithCopy(_getOpaquePointer(), const_cast<char *>(other._getOpaquePointer()), metadata._0);
+// CHECK-NEXT:   }
 // CHECK-NEXT:   inline StructWithRefcountedMember(StructWithRefcountedMember &&) = default;
 // CHECK-NEXT: private:

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

@@ -22,7 +22,9 @@
 // CHECK:      class StructWithIntField final {
 // CHECK-NEXT: public:
 // CHECK-NEXT:   inline ~StructWithIntField() {
-// CHECK:        inline StructWithIntField(const StructWithIntField &) = default;
+// CHECK:        }
+// CHECK-NEXT:   inline StructWithIntField(const StructWithIntField &other) {
+// CHECK:        }
 // CHECK-NEXT:   inline StructWithIntField(StructWithIntField &&) = default;
 // CHECK-NEXT: private:
 // CHECK-NEXT:   inline StructWithIntField() {}