Merge pull request swiftlang#60381 from hyp/eng/i/class-members-docs

[interop][SwiftToCxx] add support for members in class types

Author: hyp

docs/CppInteroperability/CppInteroperabilityStatus.md

@@ -154,17 +154,25 @@ This status table describes which of the following Swift language features have
 | Copy and destroy semantics     | Yes                                                      |
 | Initializers                   | Partially, as static `init` methods. No failable support |
 
+**Class types**
+
+| **Swift Language Feature**     | **Implemented Experimental Support For Using It In C++** |
+|--------------------------------|----------------------------------------------------------|
+| Class reference values         | Yes                                                      |
+| ARC semantics                  | Yes (C++ copy constructor,assignment operator, destructor perform ARC operations)  |
+| Initializers                   | No |
+
 **Methods**
 
 | **Swift Language Feature**     | **Implemented Experimental Support For Using It In C++** |
 |--------------------------------|----------------------------------------------------------|
-| Instance methods               | Yes, for structs only                                    |
+| Instance methods               | Yes, for structs and classes only                                    |
 | Static methods                 | No                                                       |
 
 **Properties**
 
 | **Swift Language Feature**     | **Implemented Experimental Support For Using It In C++** |
 |--------------------------------|----------------------------------------------------------|
-| Getter accessors               | Yes, via `get<name>`. Boolean properties that start with `is` or `has` are remapped directly to a getter method using their original name. For structs only                   |
-| Setter accessors               | Yes, via `set<name>`. For structs only                   |
+| Getter accessors               | Yes, via `get<name>`. Boolean properties that start with `is` or `has` are remapped directly to a getter method using their original name. For structs and classes only                   |
+| Setter accessors               | Yes, via `set<name>`. For structs and classes only                   |
 | Mutation accessors             | No                                                       |

docs/CppInteroperability/UserGuide-CallingSwiftFromC++.md

@@ -7,7 +7,7 @@ A Swift library author might want to expose their interface to C++, to allow a C
 **NOTE:** This document does not go over the following Swift language features yet:
 
 * Closures
-* inheritance
+* overriden methods/properties in classes
 * Existential types (any P)
 * Nested types
 * Operators
@@ -626,6 +626,46 @@ The Swift `Person` class instance that C++ variable `p` referenced gets dealloca
 at the end of `createAndUsePerson` as the two C++ values that referenced it
 inside of `createAndUsePerson` were destroyed.
 
+### Class inheritance
+
+A Swift class that inherits from another class is bridged to C++ with that inheritance
+relationship preserved in the C++ class hierarchy generated for these Swift classes. For example, given the following two Swift classes:
+
+```swift
+// Swift module 'Transport'
+public class Vehicle {
+}
+public final class Bicycle: Vehicle {
+}
+```
+
+Get a corresponding C++ class hierachy in C++:
+
+```c++
+class Vehicle { ... };
+class Bicycle final : public Vehicle {};
+```
+
+This allows C++ code to implicitly cast derived class instances to base class reference values, like in the example below:
+
+```c++
+#include "Transport-Swift.h"
+
+using namespace Transport;
+
+void doSomethingWithVehicle(Transport::Vehicle vehicle) {
+  ...
+}
+
+void useBicycle() {
+  auto bike = Bicycle::init();
+  doSomethingWithVehicle(bike);
+}
+```
+
+Swift classes that are marked as `final` are also marked `final` in C++.
+Swift classes that are not marked as `final` should not be derived from in C++.
+
 ## Accessing Properties In C++
 
 Swift allows structures and classes to define stored and computed properties. Stored properties store constant and variable values as part of an instance, whereas computed properties calculate (rather than store) a value. The stored and the computed properties from Swift types are bridged over as getter `get...` and setter `set...` methods in C++. Setter methods are not marked as `const` and should only be invoked on non `const` instances of the bridged types.

lib/PrintAsClang/DeclAndTypePrinter.cpp

@@ -300,9 +300,10 @@ class DeclAndTypePrinter::Implementation
     if (outputLang == OutputLanguageMode::Cxx) {
       // FIXME: Non objc class.
       // FIXME: Print availability.
-      ClangClassTypePrinter(os).printClassTypeDecl(CD, []() {
-        // FIXME: print class body.
-      });
+      ClangClassTypePrinter(os).printClassTypeDecl(
+          CD, [&]() { printMembers(CD->getMembers()); });
+      os << outOfLineDefinitions;
+      outOfLineDefinitions.clear();
       return;
     }
 

lib/PrintAsClang/PrintClangClassType.cpp

@@ -59,7 +59,7 @@ void ClangClassTypePrinter::printClassTypeDecl(
 
   os << "  using " << baseClassName << "::" << baseClassName << ";\n";
   os << "  using " << baseClassName << "::operator=;\n";
-
+  bodyPrinter();
   os << "protected:\n";
   os << "  inline ";
   printer.printBaseName(typeDecl);

lib/PrintAsClang/PrintClangFunction.cpp

@@ -78,9 +78,9 @@ bool isKnownCType(Type t, PrimitiveTypeMapping &typeMapping) {
 }
 
 struct CFunctionSignatureTypePrinterModifierDelegate {
-  /// Prefix the indirect value type param being printed in C mode.
+  /// Prefix the indirect value type / class type param being printed in C mode.
   Optional<llvm::function_ref<void(raw_ostream &)>>
-      prefixIndirectParamValueTypeInC = None;
+      prefixIndirectlyPassedParamTypeInC = None;
 };
 
 // Prints types in the C function signature that corresponds to the
@@ -152,6 +152,8 @@ class CFunctionSignatureTypePrinter
                       bool isInOutParam) {
     // FIXME: handle optionalKind.
     if (languageMode != OutputLanguageMode::Cxx) {
+      if (modifiersDelegate.prefixIndirectlyPassedParamTypeInC)
+        (*modifiersDelegate.prefixIndirectlyPassedParamTypeInC)(os);
       os << "void * _Nonnull";
       if (isInOutParam)
         os << " * _Nonnull";
@@ -188,8 +190,8 @@ class CFunctionSignatureTypePrinter
       if (languageMode != OutputLanguageMode::Cxx &&
           (decl->isResilient() ||
            interopContext.getIrABIDetails().shouldPassIndirectly(NT))) {
-        if (modifiersDelegate.prefixIndirectParamValueTypeInC)
-          (*modifiersDelegate.prefixIndirectParamValueTypeInC)(os);
+        if (modifiersDelegate.prefixIndirectlyPassedParamTypeInC)
+          (*modifiersDelegate.prefixIndirectlyPassedParamTypeInC)(os);
         // FIXME: it would be nice to print out the C struct type here.
         if (isInOutParam) {
           os << "void * _Nonnull";
@@ -407,13 +409,13 @@ void DeclAndTypeClangFunctionPrinter::printFunctionSignature(
     interleaveComma(additionalParams, os, [&](const AdditionalParam &param) {
       if (param.role == AdditionalParam::Role::Self) {
         CFunctionSignatureTypePrinterModifierDelegate delegate;
-        delegate.prefixIndirectParamValueTypeInC = [](raw_ostream &os) {
+        delegate.prefixIndirectlyPassedParamTypeInC = [](raw_ostream &os) {
           os << "SWIFT_CONTEXT ";
         };
         if (FD->hasThrows())
           os << "SWIFT_CONTEXT ";
         if (param.isIndirect) {
-          (*delegate.prefixIndirectParamValueTypeInC)(os);
+          (*delegate.prefixIndirectlyPassedParamTypeInC)(os);
           os << "void * _Nonnull _self";
         } else {
           print(param.type, OptionalTypeKind::OTK_None, "_self",
@@ -649,7 +651,8 @@ void DeclAndTypeClangFunctionPrinter::printCxxMethod(
   modifiers.isInline = true;
   bool isMutating =
       isa<FuncDecl>(FD) ? cast<FuncDecl>(FD)->isMutating() : false;
-  modifiers.isConst = !isMutating && !isConstructor;
+  modifiers.isConst =
+      !isa<ClassDecl>(typeDeclContext) && !isMutating && !isConstructor;
   printFunctionSignature(
       FD, isConstructor ? "init" : FD->getName().getBaseIdentifier().get(),
       resultTy, FunctionSignatureKind::CxxInlineThunk, {}, modifiers);
@@ -710,7 +713,7 @@ void DeclAndTypeClangFunctionPrinter::printCxxPropertyAccessorMethod(
   if (isDefinition)
     modifiers.qualifierContext = typeDeclContext;
   modifiers.isInline = true;
-  modifiers.isConst = accessor->isGetter();
+  modifiers.isConst = accessor->isGetter() && !isa<ClassDecl>(typeDeclContext);
   printFunctionSignature(accessor, remapPropertyName(accessor, resultTy),
                          resultTy, FunctionSignatureKind::CxxInlineThunk, {},
                          modifiers);

test/Interop/SwiftToCxx/methods/method-in-cxx-execution.cpp

@@ -31,5 +31,37 @@ int main() {
   auto largeStructAdded = largeStructDoubled.added(largeStruct);
   largeStructAdded.dump();
 // CHECK-NEXT: -3, 6, -300, 126, 201, -30303
+
+  {
+    auto classValue = createClassWithMethods(42);
+    classValue.dump();
+// CHECK-NEXT: ClassWithMethods 42;
+    auto classValueRef = classValue.sameRet();
+    auto classValueOther = classValue.deepCopy(2);
+    classValue.mutate();
+    classValue.dump();
+    classValueRef.dump();
+    classValueOther.dump();
+  }
+// CHECK-NEXT: ClassWithMethods -42;
+// CHECK-NEXT: ClassWithMethods -42;
+// CHECK-NEXT: ClassWithMethods 44;
+// CHECK-NEXT: ClassWithMethods 44 deinit
+// CHECK-NEXT: ClassWithMethods -42 deinit
+
+  auto classWithStruct = createPassStructInClassMethod();
+  {
+    auto largeStruct = classWithStruct.retStruct(-11);
+    largeStruct.dump();
+// CHECK-NEXT: PassStructInClassMethod.retStruct -11;
+// CHECK-NEXT: 1, 2, 3, 4, 5, 6
+  }
+  classWithStruct.updateStruct(-578, largeStruct);
+  {
+    auto largeStruct = classWithStruct.retStruct(2);
+    largeStruct.dump();
+// CHECK-NEXT: PassStructInClassMethod.retStruct 2;
+// CHECK-NEXT: -578, 2, -100, 42, 67, -10101
+  }
   return 0;
 }

test/Interop/SwiftToCxx/methods/method-in-cxx.swift

@@ -24,10 +24,78 @@ public struct LargeStruct {
     }
 }
 
+public final class ClassWithMethods {
+    var field: Int
+
+    init(_ x: Int) {
+      field = x
+    }
+
+    deinit {
+        print("ClassWithMethods \(field) deinit")
+    }
+
+    public func dump() {
+        print("ClassWithMethods \(field);")
+    }
+
+    public func sameRet() -> ClassWithMethods {
+        return self
+    }
+
+    public func mutate() {
+        field = -field
+    }
+
+    public func deepCopy(_ x: Int) -> ClassWithMethods {
+        return ClassWithMethods(field + x)
+    }
+}
+
+public final class PassStructInClassMethod {
+    var largeStruct: LargeStruct
+    init() { largeStruct = LargeStruct(x1: 1, x2: 2, x3: 3, x4: 4, x5: 5, x6: 6) }
+
+    public func retStruct(_ x: Int) -> LargeStruct {
+        print("PassStructInClassMethod.retStruct \(x);")
+        return largeStruct
+    }
+    public func updateStruct(_ x: Int, _ y: LargeStruct) {
+        largeStruct = LargeStruct(x1: x, x2: y.x2, x3: y.x3, x4: y.x4, x5: y.x5, x6: y.x6)
+    }
+}
+
+// CHECK: SWIFT_EXTERN void $s7Methods09ClassWithA0C4dumpyyF(SWIFT_CONTEXT void * _Nonnull _self) SWIFT_NOEXCEPT SWIFT_CALL; // dump()
+// CHECK: SWIFT_EXTERN void * _Nonnull $s7Methods09ClassWithA0C7sameRetACyF(SWIFT_CONTEXT void * _Nonnull _self) SWIFT_NOEXCEPT SWIFT_CALL; // sameRet()
+// CHECK: SWIFT_EXTERN void $s7Methods09ClassWithA0C6mutateyyF(SWIFT_CONTEXT void * _Nonnull _self) SWIFT_NOEXCEPT SWIFT_CALL; // mutate()
+// CHECK: SWIFT_EXTERN void * _Nonnull $s7Methods09ClassWithA0C8deepCopyyACSiF(ptrdiff_t x, SWIFT_CONTEXT void * _Nonnull _self) SWIFT_NOEXCEPT SWIFT_CALL; // deepCopy(_:)
 // CHECK: SWIFT_EXTERN void $s7Methods11LargeStructV7doubledACyF(SWIFT_INDIRECT_RESULT void * _Nonnull, SWIFT_CONTEXT const void * _Nonnull _self) SWIFT_NOEXCEPT SWIFT_CALL; // doubled()
 // CHECK:  SWIFT_EXTERN void $s7Methods11LargeStructV4dumpyyF(SWIFT_CONTEXT const void * _Nonnull _self) SWIFT_NOEXCEPT SWIFT_CALL; // dump()
 // CHECK:  SWIFT_EXTERN void $s7Methods11LargeStructV6scaledyACSi_SitF(SWIFT_INDIRECT_RESULT void * _Nonnull, ptrdiff_t x, ptrdiff_t y, SWIFT_CONTEXT const void * _Nonnull _self) SWIFT_NOEXCEPT SWIFT_CALL; // scaled(_:_:)
 // CHECK:  SWIFT_EXTERN void $s7Methods11LargeStructV5addedyA2CF(SWIFT_INDIRECT_RESULT void * _Nonnull, const void * _Nonnull x, SWIFT_CONTEXT const void * _Nonnull _self) SWIFT_NOEXCEPT SWIFT_CALL; // added(_:)
+// CHECK: SWIFT_EXTERN void $s7Methods23PassStructInClassMethodC03retC0yAA05LargeC0VSiF(SWIFT_INDIRECT_RESULT void * _Nonnull, ptrdiff_t x, SWIFT_CONTEXT void * _Nonnull _self) SWIFT_NOEXCEPT SWIFT_CALL; // retStruct(_:)
+// CHECK: SWIFT_EXTERN void $s7Methods23PassStructInClassMethodC06updateC0yySi_AA05LargeC0VtF(ptrdiff_t x, const void * _Nonnull y, SWIFT_CONTEXT void * _Nonnull _self) SWIFT_NOEXCEPT SWIFT_CALL; // updateStruct(_:_:)
+
+// CHECK: class ClassWithMethods final : public swift::_impl::RefCountedClass {
+// CHECK:   using RefCountedClass::RefCountedClass;
+// CHECK-NEXT:   using RefCountedClass::operator=;
+// CHECK-NEXT:   inline void dump();
+// CHECK-NEXT:   inline ClassWithMethods sameRet();
+// CHECK-NEXT:   inline void mutate();
+// CHECK-NEXT:   inline ClassWithMethods deepCopy(swift::Int x);
+
+// CHECK: inline void ClassWithMethods::dump() {
+// CHECK-NEXT: return _impl::$s7Methods09ClassWithA0C4dumpyyF(::swift::_impl::_impl_RefCountedClass::getOpaquePointer(*this));
+// CHECK-NEXT: }
+// CHECK-NEXT: inline ClassWithMethods ClassWithMethods::sameRet() {
+// CHECK-NEXT: return _impl::_impl_ClassWithMethods::makeRetained(_impl::$s7Methods09ClassWithA0C7sameRetACyF(::swift::_impl::_impl_RefCountedClass::getOpaquePointer(*this)));
+// CHECK-NEXT: }
+// CHECK-NEXT: inline void ClassWithMethods::mutate() {
+// CHECK-NEXT: return _impl::$s7Methods09ClassWithA0C6mutateyyF(::swift::_impl::_impl_RefCountedClass::getOpaquePointer(*this));
+// CHECK-NEXT: }
+// CHECK-NEXT: inline ClassWithMethods ClassWithMethods::deepCopy(swift::Int x) {
+// CHECK-NEXT: return _impl::_impl_ClassWithMethods::makeRetained(_impl::$s7Methods09ClassWithA0C8deepCopyyACSiF(x, ::swift::_impl::_impl_RefCountedClass::getOpaquePointer(*this)));
+// CHECK-NEXT: }
 
 // CHECK: class LargeStruct final {
 // CHECK: inline LargeStruct(LargeStruct &&) = default;
@@ -56,6 +124,23 @@ public struct LargeStruct {
 // CHECK-NEXT: });
 // CHECK-NEXT: }
 
+// CHECK: inline LargeStruct PassStructInClassMethod::retStruct(swift::Int x) {
+// CHECK-NEXT: return _impl::_impl_LargeStruct::returnNewValue([&](void * _Nonnull result) {
+// CHECK-NEXT:   _impl::$s7Methods23PassStructInClassMethodC03retC0yAA05LargeC0VSiF(result, x, ::swift::_impl::_impl_RefCountedClass::getOpaquePointer(*this));
+// CHECK-NEXT: });
+// CHECK-NEXT: }
+// CHECK-NEXT: inline void PassStructInClassMethod::updateStruct(swift::Int x, const LargeStruct& y) {
+// CHECK-NEXT: return _impl::$s7Methods23PassStructInClassMethodC06updateC0yySi_AA05LargeC0VtF(x, _impl::_impl_LargeStruct::getOpaquePointer(y), ::swift::_impl::_impl_RefCountedClass::getOpaquePointer(*this));
+// CHECK-NEXT: }
+
+public func createClassWithMethods(_ x: Int) -> ClassWithMethods {
+    return ClassWithMethods(x)
+}
+
 public func createLargeStruct() -> LargeStruct {
     return LargeStruct(x1: -1, x2: 2, x3: -100, x4: 42, x5: 67, x6: -10101)
 }
+
+public func createPassStructInClassMethod() -> PassStructInClassMethod {
+    return PassStructInClassMethod()
+}

test/Interop/SwiftToCxx/properties/getter-in-cxx-execution.cpp

@@ -53,5 +53,11 @@ int main() {
 // CHECK-NEXT: create RefCountedClass 1
 // CHECK-NEXT: destroy RefCountedClass 1
 // CHECK-NEXT: destroy RefCountedClass 0
+
+  auto propsInClass = createPropsInClass(-1234);
+  assert(propsInClass.getStoredInt() == -1234);
+  assert(propsInClass.getComputedInt() == -1235);
+  auto smallStructFromClass = propsInClass.getSmallStruct();
+  assert(smallStructFromClass.getX() == 1234);
   return 0;
 }

test/Interop/SwiftToCxx/properties/getter-in-cxx.swift

@@ -72,6 +72,44 @@ public struct LargeStruct {
 // CHECK-NEXT: });
 // CHECK-NEXT: }
 
+public final class PropertiesInClass {
+    public let storedInt: Int32
+
+    init(_ x: Int32) {
+        storedInt = x
+    }
+
+    public var computedInt: Int {
+        return Int(storedInt) - 1
+    }
+
+    public var smallStruct: FirstSmallStruct {
+        return FirstSmallStruct(x: UInt32(-storedInt));
+    }
+}
+
+// CHECK: class PropertiesInClass final : public swift::_impl::RefCountedClass {
+// CHECK: using RefCountedClass::operator=;
+// CHECK-NEXT: inline int32_t getStoredInt();
+// CHECK-NEXT: inline swift::Int getComputedInt();
+// CHECK-NEXT: inline FirstSmallStruct getSmallStruct();
+
+// CHECK: inline int32_t PropertiesInClass::getStoredInt() {
+// CHECK-NEXT: return _impl::$s10Properties0A7InClassC9storedInts5Int32Vvg(::swift::_impl::_impl_RefCountedClass::getOpaquePointer(*this));
+// CHECK-NEXT: }
+// CHECK-NEXT: inline swift::Int PropertiesInClass::getComputedInt() {
+// CHECK-NEXT: return _impl::$s10Properties0A7InClassC11computedIntSivg(::swift::_impl::_impl_RefCountedClass::getOpaquePointer(*this));
+// CHECK-NEXT: }
+// CHECK-NEXT: inline FirstSmallStruct PropertiesInClass::getSmallStruct() {
+// CHECK-NEXT: return _impl::_impl_FirstSmallStruct::returnNewValue([&](char * _Nonnull result) {
+// CHECK-NEXT:   _impl::swift_interop_returnDirect_Properties_FirstSmallStruct(result, _impl::$s10Properties0A7InClassC11smallStructAA010FirstSmallE0Vvg(::swift::_impl::_impl_RefCountedClass::getOpaquePointer(*this)));
+// CHECK-NEXT: });
+// CHECK-NEXT: }
+
+public func createPropsInClass(_ x: Int32) -> PropertiesInClass {
+    return PropertiesInClass(x)
+}
+
 public struct SmallStructWithGetters {
     public let storedInt: UInt32
     public var computedInt: Int {

test/Interop/SwiftToCxx/properties/setter-in-cxx-execution.cpp

@@ -47,5 +47,13 @@ int main() {
 
   smallStructWithProps.setLargeStructWithProps(largeStructWithProps);
 // CHECK-NEXT: SET: LargeStruct(x1: 0, x2: 2, x3: -72, x4: 3, x5: 4, x6: 5), FirstSmallStruct(x: 999)
+
+  auto propsInClass = createPropsInClass(-1234);
+  assert(propsInClass.getStoredInt() == -1234);
+  propsInClass.setStoredInt(45);
+  assert(propsInClass.getStoredInt() == 45);
+  propsInClass.setComputedInt(-11);
+  assert(propsInClass.getComputedInt() == -11);
+  assert(propsInClass.getStoredInt() == -13);
   return 0;
 }