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Jul 25, 2023
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[cxx-interop] Import mutating dereference operators #67375

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86 changes: 53 additions & 33 deletions lib/ClangImporter/ImportDecl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2186,17 +2186,6 @@ namespace {
// The name of every member.
llvm::DenseSet<StringRef> allMemberNames;

bool hasConstOperatorStar = false;
for (auto member : decl->decls()) {
if (auto method = dyn_cast<clang::CXXMethodDecl>(member)) {
if (method->getOverloadedOperator() ==
clang::OverloadedOperatorKind::OO_Star &&
method->param_empty() && method->isConst())
hasConstOperatorStar = true;
}
}
bool hasSynthesizedPointeeProperty = false;

// FIXME: Import anonymous union fields and support field access when
// it is nested in a struct.
for (auto m : decl->decls()) {
Expand Down Expand Up @@ -2275,26 +2264,11 @@ namespace {

if (auto MD = dyn_cast<FuncDecl>(member)) {
if (auto cxxMethod = dyn_cast<clang::CXXMethodDecl>(m)) {
ImportedName methodImportedName =
Impl.importFullName(cxxMethod, getActiveSwiftVersion());
auto cxxOperatorKind = cxxMethod->getOverloadedOperator();

if (cxxOperatorKind == clang::OO_Star && cxxMethod->param_empty()) {
// This is a dereference operator. We synthesize a computed
// property called `pointee` for it.

// If this record has multiple overloads of `operator*`, prefer
// the const overload if it exists.
if ((cxxMethod->isConst() || !hasConstOperatorStar) &&
!hasSynthesizedPointeeProperty) {
VarDecl *pointeeProperty =
synthesizer.makeDereferencedPointeeProperty(MD);
result->addMember(pointeeProperty);
hasSynthesizedPointeeProperty = true;
}

Impl.markUnavailable(MD, "use .pointee property");
MD->overwriteAccess(AccessLevel::Private);
} else if (cxxOperatorKind ==
clang::OverloadedOperatorKind::OO_PlusPlus) {
if (cxxOperatorKind == clang::OverloadedOperatorKind::OO_PlusPlus) {
// Make sure the type is not a foreign reference type.
// We cannot handle `operator++` for those types, since the
// current implementation creates a new instance of the type.
Expand All @@ -2319,8 +2293,8 @@ namespace {
clang::OverloadedOperatorKind::OO_PlusPlus &&
cxxOperatorKind !=
clang::OverloadedOperatorKind::OO_Call &&
cxxOperatorKind !=
clang::OverloadedOperatorKind::OO_Subscript) {
!methodImportedName.isSubscriptAccessor() &&
!methodImportedName.isDereferenceAccessor()) {

auto opFuncDecl = synthesizer.makeOperator(MD, cxxMethod);

Expand Down Expand Up @@ -2551,6 +2525,18 @@ namespace {
auto *subscriptImpl = getterAndSetter.first ? getterAndSetter.first : getterAndSetter.second;
Impl.addAlternateDecl(subscriptImpl, subscript);
}

if (Impl.cxxDereferenceOperators.find(result) !=
Impl.cxxDereferenceOperators.end()) {
// If this type has a dereference operator, synthesize a computed
// property called `pointee` for it.
auto getterAndSetter = Impl.cxxDereferenceOperators[result];

VarDecl *pointeeProperty =
synthesizer.makeDereferencedPointeeProperty(
getterAndSetter.first, getterAndSetter.second);
result->addMember(pointeeProperty);
}
}

result->setMemberLoader(&Impl, 0);
Expand Down Expand Up @@ -3191,6 +3177,8 @@ namespace {
case ImportedAccessorKind::None:
case ImportedAccessorKind::SubscriptGetter:
case ImportedAccessorKind::SubscriptSetter:
case ImportedAccessorKind::DereferenceGetter:
case ImportedAccessorKind::DereferenceSetter:
break;

case ImportedAccessorKind::PropertyGetter: {
Expand Down Expand Up @@ -3531,6 +3519,8 @@ namespace {
}
}

bool makePrivate = false;

if (importedName.isSubscriptAccessor() && !importFuncWithoutSignature) {
assert(func->getParameters()->size() == 1);
auto typeDecl = dc->getSelfNominalTypeDecl();
Expand Down Expand Up @@ -3558,8 +3548,32 @@ namespace {

Impl.markUnavailable(func, "use subscript");
}
// Someday, maybe this will need to be 'open' for C++ virtual methods.
func->setAccess(AccessLevel::Public);

if (importedName.isDereferenceAccessor() &&
!importFuncWithoutSignature) {
auto typeDecl = dc->getSelfNominalTypeDecl();
auto &getterAndSetter = Impl.cxxDereferenceOperators[typeDecl];

switch (importedName.getAccessorKind()) {
case ImportedAccessorKind::DereferenceGetter:
getterAndSetter.first = func;
break;
case ImportedAccessorKind::DereferenceSetter:
getterAndSetter.second = func;
break;
default:
llvm_unreachable("invalid dereference operator kind");
}

Impl.markUnavailable(func, "use .pointee property");
makePrivate = true;
}

if (makePrivate)
func->setAccess(AccessLevel::Private);
else
// Someday, maybe this will need to be 'open' for C++ virtual methods.
func->setAccess(AccessLevel::Public);
}

result->setIsObjC(false);
Expand Down Expand Up @@ -3983,6 +3997,10 @@ namespace {
case ImportedAccessorKind::SubscriptSetter:
case ImportedAccessorKind::None:
return importObjCMethodDecl(decl, dc, llvm::None);

case ImportedAccessorKind::DereferenceGetter:
case ImportedAccessorKind::DereferenceSetter:
llvm_unreachable("dereference operators only exist in C++");
}
}

Expand Down Expand Up @@ -6045,6 +6063,8 @@ SwiftDeclConverter::getImplicitProperty(ImportedName importedName,
case ImportedAccessorKind::None:
case ImportedAccessorKind::SubscriptGetter:
case ImportedAccessorKind::SubscriptSetter:
case ImportedAccessorKind::DereferenceGetter:
case ImportedAccessorKind::DereferenceSetter:
llvm_unreachable("Not a property accessor");

case ImportedAccessorKind::PropertyGetter:
Expand Down
11 changes: 11 additions & 0 deletions lib/ClangImporter/ImportName.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -334,6 +334,8 @@ void ClangImporter::Implementation::printSwiftName(ImportedName name,
bool isSetter = false;
switch (name.getAccessorKind()) {
case ImportedAccessorKind::None:
case ImportedAccessorKind::DereferenceGetter:
case ImportedAccessorKind::DereferenceSetter:
break;

case ImportedAccessorKind::PropertyGetter:
Expand Down Expand Up @@ -1916,6 +1918,15 @@ ImportedName NameImporter::importNameImpl(const clang::NamedDecl *D,
baseName = swiftCtx.getIdentifier(operatorName).str();
isFunction = true;
addEmptyArgNamesForClangFunction(functionDecl, argumentNames);
if (auto cxxMethod = dyn_cast<clang::CXXMethodDecl>(functionDecl)) {
if (op == clang::OverloadedOperatorKind::OO_Star &&
cxxMethod->param_empty()) {
if (cxxMethod->isConst())
result.info.accessorKind = ImportedAccessorKind::DereferenceGetter;
else
result.info.accessorKind = ImportedAccessorKind::DereferenceSetter;
}
}
break;
}
case clang::OverloadedOperatorKind::OO_Call:
Expand Down
23 changes: 23 additions & 0 deletions lib/ClangImporter/ImportName.h
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,8 @@ enum class ImportedAccessorKind : unsigned {
PropertySetter,
SubscriptGetter,
SubscriptSetter,
DereferenceGetter,
DereferenceSetter,
};
enum { NumImportedAccessorKindBits = 3 };

Expand Down Expand Up @@ -324,6 +326,8 @@ class ImportedName {
case ImportedAccessorKind::None:
case ImportedAccessorKind::SubscriptGetter:
case ImportedAccessorKind::SubscriptSetter:
case ImportedAccessorKind::DereferenceGetter:
case ImportedAccessorKind::DereferenceSetter:
return false;

case ImportedAccessorKind::PropertyGetter:
Expand All @@ -338,6 +342,8 @@ class ImportedName {
case ImportedAccessorKind::None:
case ImportedAccessorKind::PropertyGetter:
case ImportedAccessorKind::PropertySetter:
case ImportedAccessorKind::DereferenceGetter:
case ImportedAccessorKind::DereferenceSetter:
return false;

case ImportedAccessorKind::SubscriptGetter:
Expand All @@ -347,6 +353,23 @@ class ImportedName {

llvm_unreachable("Invalid ImportedAccessorKind.");
}

bool isDereferenceAccessor() const {
switch (getAccessorKind()) {
case ImportedAccessorKind::None:
case ImportedAccessorKind::PropertyGetter:
case ImportedAccessorKind::PropertySetter:
case ImportedAccessorKind::SubscriptGetter:
case ImportedAccessorKind::SubscriptSetter:
return false;

case ImportedAccessorKind::DereferenceGetter:
case ImportedAccessorKind::DereferenceSetter:
return true;
}

llvm_unreachable("Invalid ImportedAccessorKind.");
}
};

/// Strips a trailing "Notification", if present. Returns {} if name doesn't end
Expand Down
3 changes: 3 additions & 0 deletions lib/ClangImporter/ImporterImpl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -642,6 +642,9 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
llvm::MapVector<std::pair<NominalTypeDecl *, Type>,
std::pair<FuncDecl *, FuncDecl *>> cxxSubscripts;

llvm::MapVector<NominalTypeDecl *, std::pair<FuncDecl *, FuncDecl *>>
cxxDereferenceOperators;

llvm::SmallPtrSet<const clang::Decl *, 1> synthesizedAndAlwaysVisibleDecls;

private:
Expand Down
68 changes: 54 additions & 14 deletions lib/ClangImporter/SwiftDeclSynthesizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1538,17 +1538,22 @@ synthesizeUnwrappingGetterBody(AbstractFunctionDecl *afd, void *context) {
return {body, /*isTypeChecked*/ true};
}

/// Synthesizer callback for a subscript setter.
/// Synthesizer callback for a subscript setter or a setter for a dereference
/// property (`var pointee`).
static std::pair<BraceStmt *, bool>
synthesizeSubscriptSetterBody(AbstractFunctionDecl *afd, void *context) {
synthesizeUnwrappingSetterBody(AbstractFunctionDecl *afd, void *context) {
auto setterDecl = cast<AccessorDecl>(afd);
auto setterImpl = static_cast<FuncDecl *>(context);

ASTContext &ctx = setterDecl->getASTContext();

auto selfArg = createSelfArg(setterDecl);
DeclRefExpr *valueParamRefExpr = createParamRefExpr(setterDecl, 0);
DeclRefExpr *keyParamRefExpr = createParamRefExpr(setterDecl, 1);
// For a subscript this decl will have two parameters, for a pointee property
// it will only have one.
DeclRefExpr *keyParamRefExpr = setterDecl->getParameters()->size() == 1
? nullptr
: createParamRefExpr(setterDecl, 1);

Type elementTy = valueParamRefExpr->getDecl()->getInterfaceType();

Expand Down Expand Up @@ -1644,7 +1649,7 @@ SubscriptDecl *SwiftDeclSynthesizer::makeSubscript(FuncDecl *getter,
setterDecl->setImplicit();
setterDecl->setIsDynamic(false);
setterDecl->setIsTransparent(true);
setterDecl->setBodySynthesizer(synthesizeSubscriptSetterBody, setterImpl);
setterDecl->setBodySynthesizer(synthesizeUnwrappingSetterBody, setterImpl);

if (setterImpl->isMutating()) {
setterDecl->setSelfAccessKind(SelfAccessKind::Mutating);
Expand All @@ -1663,28 +1668,34 @@ SubscriptDecl *SwiftDeclSynthesizer::makeSubscript(FuncDecl *getter,

// MARK: C++ dereference operator

VarDecl *SwiftDeclSynthesizer::makeDereferencedPointeeProperty(
FuncDecl *dereferenceFunc) {
VarDecl *
SwiftDeclSynthesizer::makeDereferencedPointeeProperty(FuncDecl *getter,
FuncDecl *setter) {
assert((getter || setter) &&
"getter or setter required to generate a pointee property");

auto &ctx = ImporterImpl.SwiftContext;
auto dc = dereferenceFunc->getDeclContext();
FuncDecl *getterImpl = getter ? getter : setter;
FuncDecl *setterImpl = setter;
auto dc = getterImpl->getDeclContext();

// Get the return type wrapped in `Unsafe(Mutable)Pointer<T>`.
const auto rawElementTy = dereferenceFunc->getResultInterfaceType();
const auto rawElementTy = getterImpl->getResultInterfaceType();
// Unwrap `T`. Use rawElementTy for return by value.
const auto elementTy = rawElementTy->getAnyPointerElementType()
? rawElementTy->getAnyPointerElementType()
: rawElementTy;

auto result = new (ctx)
VarDecl(/*isStatic*/ false, VarDecl::Introducer::Var,
dereferenceFunc->getStartLoc(), ctx.getIdentifier("pointee"), dc);
getterImpl->getStartLoc(), ctx.getIdentifier("pointee"), dc);
result->setInterfaceType(elementTy);
result->setAccess(AccessLevel::Public);
result->setImplInfo(StorageImplInfo::getImmutableComputed());

AccessorDecl *getterDecl = AccessorDecl::create(
ctx, dereferenceFunc->getLoc(), dereferenceFunc->getLoc(),
AccessorKind::Get, result, SourceLoc(), StaticSpellingKind::None,
ctx, getterImpl->getLoc(), getterImpl->getLoc(), AccessorKind::Get,
result, SourceLoc(), StaticSpellingKind::None,
/*async*/ false, SourceLoc(),
/*throws*/ false, SourceLoc(), ParameterList::createEmpty(ctx), elementTy,
dc);
Expand All @@ -1693,14 +1704,43 @@ VarDecl *SwiftDeclSynthesizer::makeDereferencedPointeeProperty(
getterDecl->setIsDynamic(false);
getterDecl->setIsTransparent(true);
getterDecl->setBodySynthesizer(synthesizeUnwrappingGetterBody,
dereferenceFunc);
getterImpl);

if (dereferenceFunc->isMutating()) {
if (getterImpl->isMutating()) {
getterDecl->setSelfAccessKind(SelfAccessKind::Mutating);
result->setIsGetterMutating(true);
}

ImporterImpl.makeComputed(result, getterDecl, /*setter*/ nullptr);
AccessorDecl *setterDecl = nullptr;
if (setterImpl) {
auto paramVarDecl =
new (ctx) ParamDecl(SourceLoc(), SourceLoc(), Identifier(), SourceLoc(),
ctx.getIdentifier("newValue"), dc);
paramVarDecl->setSpecifier(ParamSpecifier::Default);
paramVarDecl->setInterfaceType(elementTy);

auto setterParamList =
ParameterList::create(ctx, {paramVarDecl});

setterDecl = AccessorDecl::create(
ctx, setterImpl->getLoc(), setterImpl->getLoc(), AccessorKind::Set,
result, SourceLoc(), StaticSpellingKind::None,
/*async*/ false, SourceLoc(),
/*throws*/ false, SourceLoc(), setterParamList,
TupleType::getEmpty(ctx), dc);
setterDecl->setAccess(AccessLevel::Public);
setterDecl->setImplicit();
setterDecl->setIsDynamic(false);
setterDecl->setIsTransparent(true);
setterDecl->setBodySynthesizer(synthesizeUnwrappingSetterBody, setterImpl);

if (setterImpl->isMutating()) {
setterDecl->setSelfAccessKind(SelfAccessKind::Mutating);
result->setIsSetterMutating(true);
}
}

ImporterImpl.makeComputed(result, getterDecl, setterDecl);
return result;
}

Expand Down
5 changes: 3 additions & 2 deletions lib/ClangImporter/SwiftDeclSynthesizer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -275,9 +275,10 @@ class SwiftDeclSynthesizer {
/// Given an imported C++ dereference operator (`operator*()`), create a
/// `pointee` computed property.
///
/// \param dereferenceFunc function returning `Unsafe(Mutable)?Pointer<T>`
/// \param getter function returning `UnsafePointer<T>`
/// \param setter function returning `UnsafeMutablePointer<T>`
/// \return computed property declaration
VarDecl *makeDereferencedPointeeProperty(FuncDecl *dereferenceFunc);
VarDecl *makeDereferencedPointeeProperty(FuncDecl *getter, FuncDecl *setter);

/// Given a C++ pre-increment operator (`operator++()`). create a non-mutating
/// function `successor() -> Self`.
Expand Down
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