[cxx-interop] Allow virtual methods to be renamed with SWIFT_NAME

lib/ClangImporter/ImportName.cpp

@@ -1531,6 +1531,11 @@ ImportedName NameImporter::importNameImpl(const clang::NamedDecl *D,
   if (isa<clang::ObjCCategoryDecl>(D))
     return ImportedName();
 
+  // C++ interop was not available in Swift 2
+  if (!swift3OrLaterName && isa<clang::CXXMethodDecl>(D)) {
+    return ImportedName();
+  }
+
   // Dig out the definition, if there is one.
   if (auto def = getDefinitionForClangTypeDecl(D)) {
     if (*def)

lib/ClangImporter/SwiftDeclSynthesizer.cpp

@@ -2105,6 +2105,8 @@ clang::CXXMethodDecl *SwiftDeclSynthesizer::synthesizeCXXForwardingMethod(
     // convention.
     newMethod->addAttr(clang::CFReturnsRetainedAttr::CreateImplicit(clangCtx));
   }
+  if (auto swiftNameAttr = method->getAttr<clang::SwiftNameAttr>())
+    newMethod->addAttr(swiftNameAttr->clone(clangCtx));
 
   llvm::SmallVector<clang::ParmVarDecl *, 4> params;
   for (size_t i = 0; i < method->getNumParams(); ++i) {

test/Interop/Cxx/class/inheritance/Inputs/virtual-methods.h

@@ -6,6 +6,8 @@ inline void testFunctionCollected() {
 
 struct Base {
   virtual void foo() = 0;
+  virtual void virtualRename() const
+      __attribute__((swift_name("swiftVirtualRename()")));
 };
 
 struct Base2 { virtual int f() = 0; };
@@ -83,6 +85,8 @@ struct IMMORTAL_FRT DerivedFromImmortal : public Immortal {
 struct IMMORTAL_FRT Immortal2 {
 public:
   virtual void virtualMethod(HasDestructor) = 0;
+  virtual void virtualRename() const
+      __attribute__((swift_name("swiftVirtualRename()")));
 };
 
 inline const ImmortalBase *_Nonnull castToImmortalBase(

test/Interop/Cxx/class/inheritance/functions-module-interface.swift

@@ -28,8 +28,6 @@
 // CHECK-NEXT:   public static func staticInBase() -> UnsafePointer<CChar>!
 // CHECK-NEXT:   @discardableResult
 // CHECK-NEXT:   public mutating func swiftRenamed(input i: Int32) -> Int32
-// CHECK-NEXT:   @available(swift, obsoleted: 3, renamed: "swiftRenamed(input:)")
-// CHECK-NEXT:   public mutating func renamed(_ i: Int32) -> Int32
 // CHECK-NEXT:   @discardableResult
 // CHECK-NEXT:   @_effects(readonly) public func pure() -> Int32
 // CHECK-NEXT:   @discardableResult
@@ -64,8 +62,6 @@
 // CHECK-NEXT:   public func returnsNonTrivialInBase() -> NonTrivial
 // CHECK-NEXT:   @discardableResult
 // CHECK-NEXT:   public mutating func swiftRenamed(input i: Int32) -> Int32
-// CHECK-NEXT:   @available(swift, obsoleted: 3, renamed: "swiftRenamed(input:)")
-// CHECK-NEXT:   public mutating func renamed(_ i: Int32) -> Int32
 // CHECK-NEXT:   @discardableResult
 // CHECK-NEXT:   @_effects(readonly) public func pure() -> Int32
 // CHECK-NEXT:   @discardableResult
@@ -96,8 +92,6 @@
 // CHECK-NEXT:   public func returnsNonTrivialInBase() -> NonTrivial
 // CHECK-NEXT:   @discardableResult
 // CHECK-NEXT:   public mutating func swiftRenamed(input i: Int32) -> Int32
-// CHECK-NEXT:   @available(swift, obsoleted: 3, renamed: "swiftRenamed(input:)")
-// CHECK-NEXT:   public mutating func renamed(_ i: Int32) -> Int32
 // CHECK-NEXT:   @discardableResult
 // CHECK-NEXT:   @_effects(readonly) public func pure() -> Int32
 // CHECK-NEXT:   @discardableResult

test/Interop/Cxx/class/inheritance/virtual-methods-module-interface.swift

@@ -7,6 +7,7 @@
 // CHECK-NEXT:   init()
 // CHECK-NEXT:   @available(*, unavailable, message: "virtual function is not available in Swift because it is pure")
 // CHECK-NEXT:   mutating func foo()
+// CHECK-NEXT:   func swiftVirtualRename()
 // CHECK: }
 
 // CHECK: struct Base3 {
@@ -34,3 +35,8 @@
 // CHECK:  func getOverridden42() -> Int32
 // CHECK:  func get42() -> Int32
 // CHECK: }
+
+// CHECK: class Immortal2 {
+// CHECK-NEXT: final func virtualMethod(_: HasDestructor)
+// CHECK-NEXT: final func swiftVirtualRename()
+// CHECK: }

test/Interop/Cxx/class/inheritance/virtual-methods-typechecker.swift

@@ -37,3 +37,14 @@ func takesDerivedFromImmortal(_ i: DerivedFromImmortal) {
   let _ = i.getIntValue()
   i.setIntValue(1)
 }
+
+func callVirtualRenamedMethod(_ b: Base) {
+  b.virtualRename()  // expected-error {{value of type 'Base' has no member 'virtualRename'}}
+  b.swiftVirtualRename()
+}
+
+@available(SwiftStdlib 5.8, *)
+func callsRenamedVirtualMethodsInFRT(_ i: Immortal2) {
+  i.virtualRename()  // expected-error {{value of type 'Immortal2' has no member 'virtualRename'}}
+  i.swiftVirtualRename()
+}

test/Interop/Cxx/class/inheritance/virtual-methods.swift

@@ -64,4 +64,12 @@ VirtualMethodsTestSuite.test("C++ virtual method with complex parameter") {
 }
 #endif
 
+if #available(SwiftStdlib 5.8, *) {
+  VirtualMethodsTestSuite.test("renamed C++ virtual method") {
+    func f(immortalClass: Immortal2) {
+      immortalClass.swiftVirtualRename()
+    }
+  } 
+}
+
 runAllTests()