Merge pull request #77878 from swiftlang/gaborh/import-rval-ref

[cxx-interop] Import rvalue references as consuming parameters

Author: Xazax-hun

lib/ClangImporter/ImportName.cpp

@@ -1478,10 +1478,14 @@ static bool suppressFactoryMethodAsInit(const clang::ObjCMethodDecl *method,
 }
 
 static void
-addEmptyArgNamesForClangFunction(const clang::FunctionDecl *funcDecl,
-                                 SmallVectorImpl<StringRef> &argumentNames) {
-  for (size_t i = 0; i < funcDecl->param_size(); ++i)
-    argumentNames.push_back(StringRef());
+addDefaultArgNamesForClangFunction(const clang::FunctionDecl *funcDecl,
+                                   SmallVectorImpl<StringRef> &argumentNames) {
+  for (size_t i = 0; i < funcDecl->param_size(); ++i) {
+    if (funcDecl->getParamDecl(i)->getType()->isRValueReferenceType())
+      argumentNames.push_back("consuming");
+    else
+      argumentNames.push_back(StringRef());
+  }
   if (funcDecl->isVariadic())
     argumentNames.push_back(StringRef());
 }
@@ -1863,7 +1867,7 @@ ImportedName NameImporter::importNameImpl(const clang::NamedDecl *D,
     // If we couldn't find a constructor decl, bail.
     if (!ctor)
       return ImportedName();
-    addEmptyArgNamesForClangFunction(ctor, argumentNames);
+    addDefaultArgNamesForClangFunction(ctor, argumentNames);
     break;
   }
 
@@ -1876,7 +1880,7 @@ ImportedName NameImporter::importNameImpl(const clang::NamedDecl *D,
     if (toType->isBooleanType()) {
       isFunction = true;
       baseName = "__convertToBool";
-      addEmptyArgNamesForClangFunction(conversionDecl, argumentNames);
+      addDefaultArgNamesForClangFunction(conversionDecl, argumentNames);
       break;
     }
     return ImportedName();
@@ -1928,7 +1932,7 @@ ImportedName NameImporter::importNameImpl(const clang::NamedDecl *D,
                               : clang::getOperatorSpelling(op);
       baseName = swiftCtx.getIdentifier(operatorName).str();
       isFunction = true;
-      addEmptyArgNamesForClangFunction(functionDecl, argumentNames);
+      addDefaultArgNamesForClangFunction(functionDecl, argumentNames);
       if (auto cxxMethod = dyn_cast<clang::CXXMethodDecl>(functionDecl)) {
         if (op == clang::OverloadedOperatorKind::OO_Star &&
             cxxMethod->param_empty()) {
@@ -1947,7 +1951,7 @@ ImportedName NameImporter::importNameImpl(const clang::NamedDecl *D,
     case clang::OverloadedOperatorKind::OO_Call:
       baseName = "callAsFunction";
       isFunction = true;
-      addEmptyArgNamesForClangFunction(functionDecl, argumentNames);
+      addDefaultArgNamesForClangFunction(functionDecl, argumentNames);
       break;
     case clang::OverloadedOperatorKind::OO_Subscript: {
       auto returnType = functionDecl->getReturnType();
@@ -1965,7 +1969,7 @@ ImportedName NameImporter::importNameImpl(const clang::NamedDecl *D,
         result.info.accessorKind = ImportedAccessorKind::SubscriptSetter;
       }
       isFunction = true;
-      addEmptyArgNamesForClangFunction(functionDecl, argumentNames);
+      addDefaultArgNamesForClangFunction(functionDecl, argumentNames);
       break;
     }
     default:
@@ -1996,7 +2000,7 @@ ImportedName NameImporter::importNameImpl(const clang::NamedDecl *D,
 
     if (auto function = dyn_cast<clang::FunctionDecl>(D)) {
       isFunction = true;
-      addEmptyArgNamesForClangFunction(function, argumentNames);
+      addDefaultArgNamesForClangFunction(function, argumentNames);
     }
     break;
 

lib/ClangImporter/ImportType.cpp

@@ -2415,6 +2415,7 @@ ClangImporter::Implementation::importParameterType(
   auto attrs = getImportTypeAttrs(param, /*isParam=*/true);
   Type swiftParamTy;
   bool isInOut = false;
+  bool isConsuming = false;
   bool isParamTypeImplicitlyUnwrapped = false;
 
   // Sometimes we import unavailable typedefs as enums. If that's the case,
@@ -2448,7 +2449,7 @@ ClangImporter::Implementation::importParameterType(
       return std::nullopt;
   } else if (isa<clang::ReferenceType>(paramTy) &&
              isa<clang::TemplateTypeParmType>(paramTy->getPointeeType())) {
-    // We don't support rvalue reference / universal perfect ref, bail.
+    // We don't support universal reference, bail.
     if (paramTy->isRValueReferenceType()) {
       addImportDiagnosticFn(Diagnostic(diag::rvalue_ref_params_not_imported));
       return std::nullopt;
@@ -2469,26 +2470,25 @@ ClangImporter::Implementation::importParameterType(
   if (!swiftParamTy) {
     // C++ reference types are brought in as direct
     // types most commonly.
-    auto refPointeeType =
-        importer::getCxxReferencePointeeTypeOrNone(paramTy.getTypePtr());
-    if (refPointeeType) {
+    if (auto refPointeeType =
+            getCxxReferencePointeeTypeOrNone(paramTy.getTypePtr())) {
       // We don't support reference type to a dependent type, just bail.
       if ((*refPointeeType)->isDependentType()) {
         return std::nullopt;
       }
 
-      // We don't support rvalue reference types, just bail.
-      if (paramTy->isRValueReferenceType()) {
-        addImportDiagnosticFn(Diagnostic(diag::rvalue_ref_params_not_imported));
-        return std::nullopt;
-      }
-
+      bool isRvalueRef = paramTy->isRValueReferenceType();
       // A C++ parameter of type `const <type> &` or `<type> &` becomes `<type>`
-      // or `inout <type>` in Swift. Note that SILGen will use the indirect
-      // parameter convention for such a type.
+      // or `inout <type>`. Moreover, `const <type> &&` or `<type> &&`
+      // becomes `<type>` or `consuming <type>`. Note that SILGen will use the
+      // indirect parameter convention for such a type.
       paramTy = *refPointeeType;
-      if (!paramTy.isConstQualified())
-        isInOut = true;
+      if (!paramTy.isConstQualified()) {
+        if (isRvalueRef)
+          isConsuming = true;
+        else
+          isInOut = true;
+      }
     }
   }
 
@@ -2552,7 +2552,7 @@ ClangImporter::Implementation::importParameterType(
   if (isInOut && isDirectUseOfForeignReferenceType(paramTy, swiftParamTy))
     isInOut = false;
 
-  return ImportParameterTypeResult{swiftParamTy, isInOut,
+  return ImportParameterTypeResult{swiftParamTy, isInOut, isConsuming,
                                    isParamTypeImplicitlyUnwrapped};
 }
 
@@ -2606,7 +2606,7 @@ static ParamDecl *getParameterInfo(ClangImporter::Implementation *impl,
                                    const clang::ParmVarDecl *param,
                                    const Identifier &name,
                                    const swift::Type &swiftParamTy,
-                                   const bool isInOut,
+                                   const bool isInOut, const bool isConsuming,
                                    const bool isParamTypeImplicitlyUnwrapped) {
   // Figure out the name for this parameter.
   Identifier bodyName = impl->importFullName(param, impl->CurrentVersion)
@@ -2632,10 +2632,12 @@ static ParamDecl *getParameterInfo(ClangImporter::Implementation *impl,
 
   // Foreign references are already references so they don't need to be passed
   // as inout.
-  paramInfo->setSpecifier(isInOut ? ParamSpecifier::InOut
-                                  : (param->getAttr<clang::LifetimeBoundAttr>()
-                                         ? ParamSpecifier::Borrowing
-                                         : ParamSpecifier::Default));
+  paramInfo->setSpecifier(
+      isConsuming ? ParamSpecifier::Consuming
+                  : (isInOut ? ParamSpecifier::InOut
+                             : (param->getAttr<clang::LifetimeBoundAttr>()
+                                    ? ParamSpecifier::Borrowing
+                                    : ParamSpecifier::Default)));
   paramInfo->setInterfaceType(swiftParamTy);
   impl->recordImplicitUnwrapForDecl(paramInfo, isParamTypeImplicitlyUnwrapped);
 
@@ -2702,6 +2704,7 @@ ParameterList *ClangImporter::Implementation::importFunctionParameterList(
     }
     auto swiftParamTy = swiftParamTyOpt->swiftTy;
     bool isInOut = swiftParamTyOpt->isInOut;
+    bool isConsuming = swiftParamTyOpt->isConsuming;
     bool isParamTypeImplicitlyUnwrapped =
         swiftParamTyOpt->isParamTypeImplicitlyUnwrapped;
 
@@ -2710,8 +2713,9 @@ ParameterList *ClangImporter::Implementation::importFunctionParameterList(
     if (index < argNames.size())
       name = argNames[index];
 
-    auto paramInfo = getParameterInfo(this, param, name, swiftParamTy, isInOut,
-                                      isParamTypeImplicitlyUnwrapped);
+    auto paramInfo =
+        getParameterInfo(this, param, name, swiftParamTy, isInOut, isConsuming,
+                         isParamTypeImplicitlyUnwrapped);
     parameters.push_back(paramInfo);
     ++index;
   }
@@ -3296,6 +3300,7 @@ ImportedType ClangImporter::Implementation::importMethodParamsAndReturnType(
     }
     auto swiftParamTy = swiftParamTyOpt->swiftTy;
     bool isInOut = swiftParamTyOpt->isInOut;
+    bool isConsuming = swiftParamTyOpt->isConsuming;
     bool isParamTypeImplicitlyUnwrapped =
         swiftParamTyOpt->isParamTypeImplicitlyUnwrapped;
 
@@ -3345,8 +3350,9 @@ ImportedType ClangImporter::Implementation::importMethodParamsAndReturnType(
     ++nameIndex;
 
     // Set up the parameter info
-    auto paramInfo = getParameterInfo(this, param, name, swiftParamTy, isInOut,
-                                      isParamTypeImplicitlyUnwrapped);
+    auto paramInfo =
+        getParameterInfo(this, param, name, swiftParamTy, isInOut, isConsuming,
+                         isParamTypeImplicitlyUnwrapped);
 
     // Determine whether we have a default argument.
     if (kind == SpecialMethodKind::Regular ||

lib/ClangImporter/ImporterImpl.h

@@ -1445,6 +1445,8 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
     swift::Type swiftTy;
     /// If the parameter is or not inout.
     bool isInOut;
+    /// If the parameter should be imported as consuming.
+    bool isConsuming;
     /// If the parameter is implicitly unwrapped or not.
     bool isParamTypeImplicitlyUnwrapped;
   };

lib/SILOptimizer/Mandatory/MoveOnlyAddressCheckerUtils.cpp

@@ -3347,6 +3347,9 @@ void MoveOnlyAddressCheckerPImpl::rewriteUses(
     bool isFinalConsume = consumes.claimConsume(destroyPair.first, bits);
 
     // Remove destroys that are not the final consuming use.
+    // TODO: for C++ types we do not want to remove destroys as the caller is
+    //       still responsible for invoking the dtor for the moved-from object.
+    //       See GH Issue #77894.
     if (!isFinalConsume) {
       destroyPair.first->eraseFromParent();
       continue;

test/Interop/Cxx/class/inheritance/using-base-members-module-interface.swift

@@ -21,6 +21,7 @@
 // CHECK-NEXT: }
 
 // CHECK: struct UsingBaseConstructorWithParam {
+// CHECK-NEXT:   init(consuming _: consuming IntBox)
 // CHECK-NEXT:   init(_: IntBox)
 // CHECK-NEXT:   init(_: UInt32)
 // CHECK-NEXT:   init(_: Int32)
@@ -29,6 +30,7 @@
 
 // CHECK: struct UsingBaseConstructorEmpty {
 // CHECK-NEXT:   init()
+// CHECK-NEXT:   init(consuming _: consuming Empty)
 // CHECK-NEXT:   init(_: Empty)
 // CHECK-NEXT:   var value: Int32
 // CHECK-NEXT: }

test/Interop/Cxx/operators/member-inline-typechecker.swift

@@ -34,13 +34,13 @@ writeOnlyIntArray[2] = 654
 let writeOnlyValue = writeOnlyIntArray[2]
 
 var readOnlyRvalueParam = ReadOnlyRvalueParam()
-let readOnlyRvalueVal = readOnlyRvalueParam[1] // expected-error {{value of type 'ReadOnlyRvalueParam' has no subscripts}}
+let readOnlyRvalueVal = readOnlyRvalueParam[consuming: 1]
 
 var readWriteRvalueParam = ReadWriteRvalueParam()
-let readWriteRvalueVal = readWriteRvalueParam[1] // expected-error {{value of type 'ReadWriteRvalueParam' has no subscripts}}
+let readWriteRvalueVal = readWriteRvalueParam[consuming: 1]
 
 var readWriteRvalueGetterParam = ReadWriteRvalueGetterParam()
-let readWriteRvalueGetterVal = readWriteRvalueGetterParam[1]
+let readWriteRvalueGetterVal = readWriteRvalueGetterParam[consuming: 1]
 
 var diffTypesArray = DifferentTypesArray()
 let diffTypesResultInt: Int32 = diffTypesArray[0]

test/Interop/Cxx/reference/reference-cannot-import-diagnostic.swift

@@ -22,9 +22,7 @@ import Test
 
 public func test() {
   var x: CInt = 2
-  acceptRValueRef(x) // expected-error {{cannot find 'acceptRValueRef' in scope}}
-  // CHECK: note: function 'acceptRValueRef' unavailable (cannot import)
-  // CHECK: note: C++ functions with rvalue reference parameters are unavailable in Swift
+  acceptRValueRef(consuming: x)
 
   notStdMove(x) // expected-error {{cannot find 'notStdMove' in scope}}
   // CHECK: note: function 'notStdMove' unavailable (cannot import)