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TypeCheckStorage.cpp
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//===--- TypeCheckStorage.cpp - Checking Properties and Subscripts -------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for properties, subscripts as well
// as their accessors.
//
//===----------------------------------------------------------------------===//
#include "CodeSynthesis.h"
#include "TypeChecker.h"
#include "TypeCheckAvailability.h"
#include "TypeCheckConcurrency.h"
#include "TypeCheckDecl.h"
#include "TypeCheckType.h"
#include "swift/AST/ASTContext.h"
#include "swift/AST/ASTWalker.h"
#include "swift/AST/DiagnosticsParse.h"
#include "swift/AST/DiagnosticsSema.h"
#include "swift/AST/Expr.h"
#include "swift/AST/GenericEnvironment.h"
#include "swift/AST/Initializer.h"
#include "swift/AST/ParameterList.h"
#include "swift/AST/Pattern.h"
#include "swift/AST/PropertyWrappers.h"
#include "swift/AST/ProtocolConformance.h"
#include "swift/AST/SourceFile.h"
#include "swift/AST/TypeCheckRequests.h"
#include "swift/AST/Types.h"
using namespace swift;
/// Set each bound variable in the pattern to have an error type.
void swift::setBoundVarsTypeError(Pattern *pattern, ASTContext &ctx) {
pattern->forEachVariable([&](VarDecl *var) {
// Don't change the type of a variable that we've been able to
// compute a type for.
if (var->hasInterfaceType())
return;
var->setInvalid();
});
}
/// Build a default initializer for the given type.
Expr *TypeChecker::buildDefaultInitializer(Type type) {
auto &Context = type->getASTContext();
// Default-initialize optional types and weak values to 'nil'.
if (type->getReferenceStorageReferent()->getOptionalObjectType())
return new (Context) NilLiteralExpr(SourceLoc(), /*Implicit=*/true);
// Build tuple literals for tuple types.
if (auto tupleType = type->getAs<TupleType>()) {
SmallVector<Expr *, 2> inits;
for (const auto &elt : tupleType->getElements()) {
if (elt.isVararg())
return nullptr;
auto eltInit = TypeChecker::buildDefaultInitializer(elt.getType());
if (!eltInit)
return nullptr;
inits.push_back(eltInit);
}
return TupleExpr::createImplicit(Context, inits, { });
}
// We don't default-initialize anything else.
return nullptr;
}
/// Does the context allow pattern bindings that don't bind any variables?
static bool contextAllowsPatternBindingWithoutVariables(DeclContext *dc) {
// Property decls in type context must bind variables.
if (dc->isTypeContext())
return false;
// Global variable decls must bind variables, except in scripts.
if (dc->isModuleScopeContext()) {
if (dc->getParentSourceFile()
&& dc->getParentSourceFile()->isScriptMode())
return true;
return false;
}
return true;
}
static bool hasStoredProperties(NominalTypeDecl *decl) {
bool isForeignReferenceTy =
isa<ClassDecl>(decl) && cast<ClassDecl>(decl)->isForeignReferenceType();
return (isa<StructDecl>(decl) ||
(isa<ClassDecl>(decl) &&
(!decl->hasClangNode() || isForeignReferenceTy)));
}
static void computeLoweredStoredProperties(NominalTypeDecl *decl) {
// Just walk over the members of the type, forcing backing storage
// for lazy properties and property wrappers to be synthesized.
for (auto *member : decl->getMembers()) {
auto *var = dyn_cast<VarDecl>(member);
if (!var || var->isStatic())
continue;
if (var->getAttrs().hasAttribute<LazyAttr>())
(void) var->getLazyStorageProperty();
if (var->hasAttachedPropertyWrapper()) {
(void) var->getPropertyWrapperAuxiliaryVariables();
(void) var->getPropertyWrapperInitializerInfo();
}
}
// If this is an actor, check conformance to the Actor protocol to
// ensure that the actor storage will get created (if needed).
if (auto classDecl = dyn_cast<ClassDecl>(decl)) {
// If this is an actor class, check conformance to the Actor protocol to
// ensure that the actor storage will get created (if needed).
if (classDecl->isActor()) {
ASTContext &ctx = decl->getASTContext();
if (auto actorProto = ctx.getProtocol(KnownProtocolKind::Actor)) {
SmallVector<ProtocolConformance *, 1> conformances;
classDecl->lookupConformance(actorProto, conformances);
for (auto conformance : conformances)
TypeChecker::checkConformance(conformance->getRootNormalConformance());
}
// If this is a distributed actor, synthesize its special stored properties.
if (classDecl->isDistributedActor()) {
if (auto actorProto = ctx.getProtocol(KnownProtocolKind::DistributedActor)) {
SmallVector<ProtocolConformance *, 1> conformances;
classDecl->lookupConformance(actorProto, conformances);
for (auto conformance : conformances)
TypeChecker::checkConformance(conformance->getRootNormalConformance());
}
}
}
}
}
/// Enumerate both the stored properties and missing members,
/// in a deterministic order.
static void enumerateStoredPropertiesAndMissing(
NominalTypeDecl *decl,
llvm::function_ref<void(VarDecl *)> addStoredProperty,
llvm::function_ref<void(MissingMemberDecl *)> addMissing) {
// If we have a distributed actor, find the id and actorSystem
// properties. We always want them first, and in a specific
// order.
VarDecl *distributedActorId = nullptr;
VarDecl *distributedActorSystem = nullptr;
if (decl->isDistributedActor()) {
ASTContext &ctx = decl->getASTContext();
for (auto *member : decl->getMembers()) {
if (auto *var = dyn_cast<VarDecl>(member)) {
if (!var->isStatic() && var->hasStorage()) {
if (var->getName() == ctx.Id_id) {
distributedActorId = var;
} else if (var->getName() == ctx.Id_actorSystem) {
distributedActorSystem = var;
}
}
if (distributedActorId && distributedActorSystem)
break;
}
}
if (distributedActorId)
addStoredProperty(distributedActorId);
if (distributedActorSystem)
addStoredProperty(distributedActorSystem);
}
for (auto *member : decl->getMembers()) {
if (auto *var = dyn_cast<VarDecl>(member)) {
if (!var->isStatic() && var->hasStorage()) {
// Skip any properties that we already emitted explicitly
if (var == distributedActorId)
continue;
if (var == distributedActorSystem)
continue;
addStoredProperty(var);
}
}
if (auto missing = dyn_cast<MissingMemberDecl>(member))
if (missing->getNumberOfFieldOffsetVectorEntries() > 0)
addMissing(missing);
}
}
ArrayRef<VarDecl *>
StoredPropertiesRequest::evaluate(Evaluator &evaluator,
NominalTypeDecl *decl) const {
if (!hasStoredProperties(decl))
return ArrayRef<VarDecl *>();
SmallVector<VarDecl *, 4> results;
// Unless we're in a source file we don't have to do anything
// special to lower lazy properties and property wrappers.
if (isa<SourceFile>(decl->getModuleScopeContext()))
computeLoweredStoredProperties(decl);
enumerateStoredPropertiesAndMissing(decl,
[&](VarDecl *var) {
results.push_back(var);
},
[](MissingMemberDecl *missing) { });
return decl->getASTContext().AllocateCopy(results);
}
ArrayRef<Decl *>
StoredPropertiesAndMissingMembersRequest::evaluate(Evaluator &evaluator,
NominalTypeDecl *decl) const {
if (!hasStoredProperties(decl))
return ArrayRef<Decl *>();
SmallVector<Decl *, 4> results;
// Unless we're in a source file we don't have to do anything
// special to lower lazy properties and property wrappers.
if (isa<SourceFile>(decl->getModuleScopeContext()))
computeLoweredStoredProperties(decl);
enumerateStoredPropertiesAndMissing(decl,
[&](VarDecl *var) {
results.push_back(var);
},
[&](MissingMemberDecl *missing) {
results.push_back(missing);
});
return decl->getASTContext().AllocateCopy(results);
}
/// Validate the \c entryNumber'th entry in \c binding.
const PatternBindingEntry *PatternBindingEntryRequest::evaluate(
Evaluator &eval, PatternBindingDecl *binding, unsigned entryNumber,
bool LeaveClosureBodiesUnchecked) const {
const auto &pbe = binding->getPatternList()[entryNumber];
auto &Context = binding->getASTContext();
// Resolve the pattern.
auto *pattern = TypeChecker::resolvePattern(binding->getPattern(entryNumber),
binding->getDeclContext(),
/*isStmtCondition*/ true);
if (!pattern) {
binding->setInvalid();
binding->getPattern(entryNumber)->setType(ErrorType::get(Context));
return &pbe;
}
binding->setPattern(entryNumber, pattern,
binding->getInitContext(entryNumber));
// Validate 'static'/'class' on properties in nominal type decls.
auto StaticSpelling = binding->getStaticSpelling();
if (StaticSpelling != StaticSpellingKind::None &&
isa<ExtensionDecl>(binding->getDeclContext())) {
if (auto *NTD = binding->getDeclContext()->getSelfNominalTypeDecl()) {
if (!isa<ClassDecl>(NTD)) {
if (StaticSpelling == StaticSpellingKind::KeywordClass) {
binding->diagnose(diag::class_var_not_in_class, false)
.fixItReplace(binding->getStaticLoc(), "static");
NTD->diagnose(diag::extended_type_declared_here);
}
}
}
}
// Reject "class" methods on actors.
if (StaticSpelling == StaticSpellingKind::KeywordClass &&
binding->getDeclContext()->getSelfClassDecl() &&
binding->getDeclContext()->getSelfClassDecl()->isActor()) {
binding->diagnose(diag::class_var_not_in_class, false)
.fixItReplace(binding->getStaticLoc(), "static");
}
// Check the pattern.
auto contextualPattern =
ContextualPattern::forPatternBindingDecl(binding, entryNumber);
Type patternType = TypeChecker::typeCheckPattern(contextualPattern);
if (patternType->hasError()) {
swift::setBoundVarsTypeError(pattern, Context);
binding->setInvalid();
pattern->setType(ErrorType::get(Context));
return &pbe;
}
llvm::SmallVector<VarDecl *, 2> vars;
binding->getPattern(entryNumber)->collectVariables(vars);
bool isReq = false;
bool shouldRequireStatic = false;
if (auto *d = binding->getDeclContext()->getAsDecl()) {
isReq = isa<ProtocolDecl>(d);
shouldRequireStatic = isa<NominalTypeDecl>(d);
}
for (auto *sv: vars) {
bool hasConst = sv->getAttrs().getAttribute<CompileTimeConstAttr>();
if (!hasConst)
continue;
bool hasStatic = StaticSpelling != StaticSpellingKind::None;
// only static _const let/var is supported
if (shouldRequireStatic && !hasStatic) {
binding->diagnose(diag::require_static_for_const);
continue;
}
if (isReq) {
continue;
}
auto varSourceFile = binding->getDeclContext()->getParentSourceFile();
auto isVarInInterfaceFile =
varSourceFile && varSourceFile->Kind == SourceFileKind::Interface;
// Don't diagnose too strictly for textual interfaces.
if (isVarInInterfaceFile) {
continue;
}
// var is only allowed in a protocol.
if (!sv->isLet()) {
binding->diagnose(diag::require_let_for_const);
}
// Diagnose when an init isn't given and it's not a compile-time constant
if (auto *init = binding->getInit(entryNumber)) {
if (!init->isSemanticallyConstExpr()) {
binding->diagnose(diag::require_const_initializer_for_const);
}
} else {
binding->diagnose(diag::require_const_initializer_for_const);
}
}
// If we have a type but no initializer, check whether the type is
// default-initializable. If so, do it.
if (!pbe.isInitialized() &&
binding->isDefaultInitializable(entryNumber) &&
pattern->hasStorage()) {
if (auto defaultInit = TypeChecker::buildDefaultInitializer(patternType)) {
// If we got a default initializer, install it and re-type-check it
// to make sure it is properly coerced to the pattern type.
binding->setInit(entryNumber, defaultInit);
}
}
// If the pattern contains some form of unresolved type, we'll need to
// check the initializer.
if (patternType->hasUnresolvedType() ||
patternType->hasPlaceholder() ||
patternType->hasUnboundGenericType()) {
TypeCheckExprOptions options;
if (LeaveClosureBodiesUnchecked) {
options |= TypeCheckExprFlags::LeaveClosureBodyUnchecked;
}
if (TypeChecker::typeCheckPatternBinding(binding, entryNumber, patternType,
options)) {
binding->setInvalid();
return &pbe;
}
// A pattern binding at top level is not allowed to pick up another decl's
// opaque result type as its type by type inference.
if (!binding->getDeclContext()->isLocalContext() &&
binding->getInit(entryNumber)->getType()->hasOpaqueArchetype()) {
// TODO: Check whether the type is the pattern binding's own opaque type.
binding->diagnose(diag::inferred_opaque_type,
binding->getInit(entryNumber)->getType());
}
} else {
// Coerce the pattern to the computed type.
if (auto newPattern = TypeChecker::coercePatternToType(
contextualPattern, patternType,
TypeResolverContext::PatternBindingDecl)) {
pattern = newPattern;
} else {
binding->setInvalid();
pattern->setType(ErrorType::get(Context));
return &pbe;
}
}
// If the pattern binding appears in a type or library file context, then
// it must bind at least one variable.
if (!contextAllowsPatternBindingWithoutVariables(binding->getDeclContext())) {
if (vars.empty()) {
// Selector for error message.
enum : unsigned {
Property,
GlobalVariable,
};
Context.Diags.diagnose(binding->getPattern(entryNumber)->getLoc(),
diag::pattern_binds_no_variables,
binding->getDeclContext()->isTypeContext()
? Property
: GlobalVariable);
}
}
return &pbe;
}
bool
IsGetterMutatingRequest::evaluate(Evaluator &evaluator,
AbstractStorageDecl *storage) const {
auto storageDC = storage->getDeclContext();
bool result = (!storage->isStatic() && storageDC->isTypeContext() &&
storageDC->hasValueSemantics());
// 'lazy' overrides the normal accessor-based rules and heavily
// restricts what accessors can be used. The getter is considered
// mutating if this is instance storage on a value type.
if (storage->getAttrs().hasAttribute<LazyAttr>()) {
return result;
}
// If we have an attached property wrapper, the getter's mutating-ness
// depends on the composition of the wrappers.
if (auto var = dyn_cast<VarDecl>(storage)) {
if (auto mut = var->getPropertyWrapperMutability()) {
return mut->Getter == PropertyWrapperMutability::Mutating
&& result;
}
}
auto checkMutability = [&](AccessorKind kind) -> bool {
auto *accessor = storage->getParsedAccessor(kind);
if (!accessor)
return false;
return accessor->isMutating();
};
// Protocol requirements are always written as '{ get }' or '{ get set }';
// the @_borrowed attribute determines if getReadImpl() becomes Get or Read.
if (isa<ProtocolDecl>(storageDC))
return checkMutability(AccessorKind::Get);
switch (storage->getReadImpl()) {
case ReadImplKind::Stored:
case ReadImplKind::Inherited:
return false;
case ReadImplKind::Get:
return checkMutability(AccessorKind::Get);
case ReadImplKind::Address:
return checkMutability(AccessorKind::Address);
case ReadImplKind::Read:
return checkMutability(AccessorKind::Read);
}
llvm_unreachable("bad impl kind");
}
bool
IsSetterMutatingRequest::evaluate(Evaluator &evaluator,
AbstractStorageDecl *storage) const {
// By default, the setter is mutating if we have an instance member of a
// value type, but this can be overridden below.
auto storageDC = storage->getDeclContext();
bool result = (!storage->isStatic() && storageDC->isTypeContext() &&
storageDC->hasValueSemantics());
// If we have an attached property wrapper, the setter is mutating
// or not based on the composition of the wrappers.
if (auto var = dyn_cast<VarDecl>(storage)) {
if (auto mut = var->getPropertyWrapperMutability()) {
bool isMutating = mut->Setter == PropertyWrapperMutability::Mutating;
if (auto *didSet = var->getParsedAccessor(AccessorKind::DidSet)) {
// If there's a didSet, we call the getter for the 'oldValue', and so
// should consider the getter's mutatingness as well
isMutating |= (mut->Getter == PropertyWrapperMutability::Mutating);
isMutating |= didSet->getAttrs().hasAttribute<MutatingAttr>();
}
if (auto *willSet = var->getParsedAccessor(AccessorKind::WillSet))
isMutating |= willSet->getAttrs().hasAttribute<MutatingAttr>();
return isMutating && result;
}
}
auto impl = storage->getImplInfo();
switch (impl.getWriteImpl()) {
case WriteImplKind::Immutable:
case WriteImplKind::Stored:
// Instance member setters are mutating; static property setters and
// top-level setters are not.
// It's important that we use this logic for "immutable" storage
// in order to handle initialization of let-properties.
return result;
case WriteImplKind::StoredWithObservers:
case WriteImplKind::InheritedWithObservers:
case WriteImplKind::Set: {
auto *setter = storage->getParsedAccessor(AccessorKind::Set);
if (setter)
result = setter->isMutating();
// As a special extra check, if the user also gave us a modify
// coroutine, check that it has the same mutatingness as the setter.
// TODO: arguably this should require the spelling to match even when
// it's the implied value.
auto modifyAccessor = storage->getParsedAccessor(AccessorKind::Modify);
if (impl.getReadWriteImpl() == ReadWriteImplKind::Modify &&
modifyAccessor != nullptr) {
auto modifyResult = modifyAccessor->isMutating();
if ((result || storage->isGetterMutating()) != modifyResult) {
modifyAccessor->diagnose(
diag::modify_mutatingness_differs_from_setter,
modifyResult ? SelfAccessKind::Mutating
: SelfAccessKind::NonMutating,
modifyResult ? SelfAccessKind::NonMutating
: SelfAccessKind::Mutating);
if (setter)
setter->diagnose(diag::previous_accessor, "setter", 0);
modifyAccessor->setInvalid();
}
}
return result;
}
case WriteImplKind::MutableAddress:
return storage->getParsedAccessor(AccessorKind::MutableAddress)
->isMutating();
case WriteImplKind::Modify:
return storage->getParsedAccessor(AccessorKind::Modify)
->isMutating();
}
llvm_unreachable("bad storage kind");
}
OpaqueReadOwnership
OpaqueReadOwnershipRequest::evaluate(Evaluator &evaluator,
AbstractStorageDecl *storage) const {
return (storage->getAttrs().hasAttribute<BorrowedAttr>()
? OpaqueReadOwnership::Borrowed
: OpaqueReadOwnership::Owned);
}
/// Insert the specified decl into the DeclContext's member list. If the hint
/// decl is specified, the new decl is inserted next to the hint.
static void addMemberToContextIfNeeded(Decl *D, DeclContext *DC,
Decl *Hint = nullptr) {
if (auto *ntd = dyn_cast<NominalTypeDecl>(DC)) {
ntd->addMember(D, Hint);
} else if (auto *ed = dyn_cast<ExtensionDecl>(DC)) {
ed->addMember(D, Hint);
} else {
assert((DC->isLocalContext() || isa<FileUnit>(DC)) &&
"Unknown declcontext");
}
}
/// Build a parameter list which can forward the formal index parameters of a
/// declaration.
///
/// \param prefix optional arguments to be prefixed onto the index
/// forwarding pattern.
static ParameterList *
buildIndexForwardingParamList(AbstractStorageDecl *storage,
ArrayRef<ParamDecl*> prefix,
ASTContext &context) {
auto subscript = dyn_cast<SubscriptDecl>(storage);
// Fast path: if this isn't a subscript, just use whatever we have.
if (!subscript)
return ParameterList::create(context, prefix);
// Clone the parameter list over for a new decl, so we get new ParamDecls.
auto indices = subscript->getIndices()->clone(context,
ParameterList::Implicit);
// Give all of the parameters meaningless names so that we can forward
// them properly. If it's declared anonymously, SILGen will think
// it's unused.
// TODO: use some special DeclBaseName for this?
for (auto param : indices->getArray()) {
if (!param->hasName())
param->setName(context.getIdentifier("anonymous"));
assert(param->hasName());
}
if (prefix.empty())
return indices;
// Otherwise, we need to build up a new parameter list.
SmallVector<ParamDecl*, 4> elements;
// Start with the fields we were given, if there are any.
elements.append(prefix.begin(), prefix.end());
elements.append(indices->begin(), indices->end());
return ParameterList::create(context, elements);
}
/// Create the generic parameters needed for the given accessor, if any.
static GenericParamList *createAccessorGenericParams(
AbstractStorageDecl *storage) {
// Accessors of generic subscripts get a copy of the subscript's
// generic parameter list, because they're not nested inside the
// subscript.
if (auto *subscript = dyn_cast<SubscriptDecl>(storage)) {
if (auto genericParams = subscript->getGenericParams())
return genericParams->clone(subscript->getDeclContext());
}
return nullptr;
}
static bool doesAccessorHaveBody(AccessorDecl *accessor) {
// Protocol requirements don't have bodies.
//
// FIXME: Revisit this if we ever get 'real' default implementations.
if (isa<ProtocolDecl>(accessor->getDeclContext()))
return false;
auto *storage = accessor->getStorage();
// NSManaged getters and setters don't have bodies.
if (storage->getAttrs().hasAttribute<NSManagedAttr>())
if (accessor->isGetterOrSetter())
return false;
return true;
}
/// Build an argument list referencing the subscript parameters for this
/// subscript accessor.
static ArgumentList *buildSubscriptArgumentList(ASTContext &ctx,
AccessorDecl *accessor) {
// Pull out the body parameters, which we should have cloned
// previously to be forwardable. Drop the initial buffer/value
// parameter in accessors that have one.
auto params = accessor->getParameters()->getArray();
auto accessorKind = accessor->getAccessorKind();
// Ignore the value parameter of a setter.
if (accessorKind == AccessorKind::Set) {
params = params.slice(1);
}
// Okay, everything else should be forwarded, build the argument list.
return buildForwardingArgumentList(params, ctx);
}
namespace {
enum class TargetImpl {
/// We're doing an ordinary storage reference.
Ordinary,
/// We're referencing the physical storage created for the storage.
Storage,
/// We're referencing this specific implementation of the storage, not
/// an override of it.
Implementation,
/// We're referencing the superclass's implementation of the storage.
Super,
/// We're referencing the backing property for a property with a wrapper
/// through the 'value' property.
Wrapper,
/// We're referencing the backing property for a property with a wrapper
/// through the 'projectedValue' property.
WrapperStorage,
};
} // end anonymous namespace
namespace {
/// Describes the information needed to perform property wrapper access via
/// the enclosing self.
struct EnclosingSelfPropertyWrapperAccess {
/// The (generic) subscript that will be used to perform the access.
SubscriptDecl *subscript;
/// The property being accessed.
VarDecl *accessedProperty;
};
}
/// Determine whether the given property should be accessed via the enclosing-self access pattern.
static Optional<EnclosingSelfPropertyWrapperAccess>
getEnclosingSelfPropertyWrapperAccess(VarDecl *property, bool forProjected) {
// The enclosing-self pattern only applies to instance properties of
// classes.
if (!property->isInstanceMember())
return None;
auto classDecl = property->getDeclContext()->getSelfClassDecl();
if (!classDecl)
return None;
// The pattern currently only works with the outermost property wrapper.
Type outermostWrapperType = property->getPropertyWrapperBackingPropertyType();
if (!outermostWrapperType)
return None;
NominalTypeDecl *wrapperTypeDecl = outermostWrapperType->getAnyNominal();
if (!wrapperTypeDecl)
return None;
// Look for a generic subscript that fits the general form we need.
auto wrapperInfo = wrapperTypeDecl->getPropertyWrapperTypeInfo();
auto subscript =
forProjected ? wrapperInfo.enclosingInstanceProjectedSubscript
: wrapperInfo.enclosingInstanceWrappedSubscript;
if (!subscript)
return None;
EnclosingSelfPropertyWrapperAccess result;
result.subscript = subscript;
if (forProjected) {
result.accessedProperty =
property->getPropertyWrapperAuxiliaryVariables().projectionVar;
} else {
result.accessedProperty = property;
}
return result;
}
static Optional<PropertyWrapperLValueness>
getPropertyWrapperLValueness(VarDecl *var) {
auto &ctx = var->getASTContext();
return evaluateOrDefault(
ctx.evaluator,
PropertyWrapperLValuenessRequest{var},
None);
}
/// Build a reference to the storage of a declaration. Returns nullptr if there
/// was an error. This should only occur if an invalid declaration was type
/// checked; another diagnostic should have been emitted already.
///
/// The resulting reference is used in synthesized property accessors and is of
/// one of the following forms:
/// 1. Without property wrappers:
/// - Stored: \c self.member
/// 2. With property wrappers:
/// - Wrapped: \c self._member.wrappedValue
/// - Composition: \c self._member.wrappedValue.wrappedValue….wrappedValue
/// - Projected: \c self._member.projectedValue
/// - Enclosed instance: \c Wrapper[_enclosedInstance: self, …]
static Expr *buildStorageReference(AccessorDecl *accessor,
AbstractStorageDecl *storage,
TargetImpl target,
bool isUsedForGetAccess,
bool isUsedForSetAccess,
ASTContext &ctx) {
// Whether the last component of the expression should be an l-value
bool isLValue = isUsedForSetAccess;
// Local function to "finish" the expression, creating a member reference
// to the given sequence of underlying variables.
Optional<EnclosingSelfPropertyWrapperAccess> enclosingSelfAccess;
// Contains the underlying wrappedValue declaration in a property wrapper
// along with whether or not the reference to this field needs to be an lvalue
llvm::SmallVector<std::pair<VarDecl *, bool>, 1> underlyingVars;
auto finish = [&](Expr *result) -> Expr * {
for (auto underlyingVarPair : underlyingVars) {
auto underlyingVar = underlyingVarPair.first;
auto isWrapperRefLValue = underlyingVarPair.second;
auto subs = result->getType()
->getWithoutSpecifierType()
->getContextSubstitutionMap(
accessor->getParentModule(),
underlyingVar->getDeclContext());
ConcreteDeclRef memberRef(underlyingVar, subs);
auto *memberRefExpr = new (ctx) MemberRefExpr(
result, SourceLoc(), memberRef, DeclNameLoc(), /*Implicit=*/true);
auto type = underlyingVar->getValueInterfaceType().subst(subs);
if (isWrapperRefLValue)
type = LValueType::get(type);
memberRefExpr->setType(type);
result = memberRefExpr;
}
return result;
};
VarDecl *selfDecl = accessor->getImplicitSelfDecl();
AccessSemantics semantics;
SelfAccessorKind selfAccessKind;
Type selfTypeForAccess = (selfDecl ? selfDecl->getType() : Type());
bool isMemberLValue = isLValue;
auto *genericEnv = accessor->getGenericEnvironment();
SubstitutionMap subs;
if (genericEnv)
subs = genericEnv->getForwardingSubstitutionMap();
switch (target) {
case TargetImpl::Ordinary:
semantics = AccessSemantics::Ordinary;
selfAccessKind = SelfAccessorKind::Peer;
break;
case TargetImpl::Storage:
semantics = AccessSemantics::DirectToStorage;
selfAccessKind = SelfAccessorKind::Peer;
break;
case TargetImpl::Implementation:
semantics = AccessSemantics::DirectToImplementation;
selfAccessKind = SelfAccessorKind::Peer;
break;
case TargetImpl::Super:
// If this really is an override, use a super-access.
if (auto override = storage->getOverriddenDecl()) {
semantics = AccessSemantics::Ordinary;
selfAccessKind = SelfAccessorKind::Super;
auto isMetatype = false;
if (auto *metaTy = selfTypeForAccess->getAs<MetatypeType>()) {
isMetatype = true;
selfTypeForAccess = metaTy->getInstanceType();
}
// Adjust the self type of the access to refer to the relevant superclass.
auto *baseClass = override->getDeclContext()->getSelfClassDecl();
selfTypeForAccess = selfTypeForAccess->getSuperclassForDecl(baseClass);
// Error recovery path. We get an ErrorType here if getSuperclassForDecl()
// fails (because, for instance, a generic parameter of a generic nominal
// type cannot be resolved).
if (!selfTypeForAccess->is<ErrorType>()) {
subs =
selfTypeForAccess->getContextSubstitutionMap(
accessor->getParentModule(),
baseClass);
}
storage = override;
if (isMetatype)
selfTypeForAccess = MetatypeType::get(selfTypeForAccess);
// Otherwise do a self-reference, which is dynamically bogus but
// should be statically valid. This should only happen in invalid cases.
} else {
semantics = AccessSemantics::Ordinary;
selfAccessKind = SelfAccessorKind::Peer;
}
break;
case TargetImpl::Wrapper: {
auto var = cast<VarDecl>(accessor->getStorage());
auto *backing = var->getPropertyWrapperBackingProperty();
// Error recovery.
if (!backing || backing->isInvalid())
return nullptr;
storage = backing;
// If the outermost property wrapper uses the enclosing self pattern,
// record that.
unsigned lastWrapperIdx = var->getAttachedPropertyWrappers().size();
unsigned firstWrapperIdx = 0;
enclosingSelfAccess =
getEnclosingSelfPropertyWrapperAccess(var, /*forProjected=*/false);
if (enclosingSelfAccess)
firstWrapperIdx = 1;
// Perform accesses to the wrappedValues along the composition chain.
if (firstWrapperIdx < lastWrapperIdx) {
auto lvalueness = *getPropertyWrapperLValueness(var);
// Figure out if the outermost wrapper instance should be an l-value
bool isLValueForGet = lvalueness.isLValueForGetAccess[firstWrapperIdx];
bool isLValueForSet = lvalueness.isLValueForSetAccess[firstWrapperIdx];
isMemberLValue = (isLValueForGet && isUsedForGetAccess) ||
(isLValueForSet && isUsedForSetAccess);
for (unsigned i : range(firstWrapperIdx, lastWrapperIdx)) {
auto wrapperInfo = var->getAttachedPropertyWrapperTypeInfo(i);
auto wrappedValue = wrapperInfo.valueVar;
// Figure out if the wrappedValue accesses should be l-values
bool isWrapperRefLValue = isLValue;
if (i < lastWrapperIdx - 1) {
bool isLValueForGet = lvalueness.isLValueForGetAccess[i+1];
bool isLValueForSet = lvalueness.isLValueForSetAccess[i+1];
isWrapperRefLValue = (isLValueForGet && isUsedForGetAccess) ||
(isLValueForSet && isUsedForSetAccess);
}
// Check for availability of wrappedValue.
if (accessor->getAccessorKind() == AccessorKind::Get ||
accessor->getAccessorKind() == AccessorKind::Read) {
if (wrappedValue->getAttrs().getUnavailable(ctx)) {
ExportContext where = ExportContext::forDeclSignature(var);
diagnoseExplicitUnavailability(
wrappedValue,
var->getAttachedPropertyWrappers()[i]->getRangeWithAt(),
where, nullptr);
}
}
underlyingVars.push_back({ wrappedValue, isWrapperRefLValue });
}
}
semantics = AccessSemantics::DirectToStorage;
selfAccessKind = SelfAccessorKind::Peer;
break;
}
case TargetImpl::WrapperStorage: {
auto var =
cast<VarDecl>(accessor->getStorage())->getOriginalWrappedProperty();
auto *backing = var->getPropertyWrapperBackingProperty();
// Error recovery.
if (!backing || backing->isInvalid())
return nullptr;
storage = backing;
enclosingSelfAccess =
getEnclosingSelfPropertyWrapperAccess(var, /*forProjected=*/true);
if (!enclosingSelfAccess) {
auto projectionVar = cast<VarDecl>(accessor->getStorage());
if (auto lvalueness = getPropertyWrapperLValueness(projectionVar)) {
isMemberLValue =
(lvalueness->isLValueForGetAccess[0] && isUsedForGetAccess) ||
(lvalueness->isLValueForSetAccess[0] && isUsedForSetAccess);
}
underlyingVars.push_back(
{ var->getAttachedPropertyWrapperTypeInfo(0).projectedValueVar,
isLValue });
}
semantics = AccessSemantics::DirectToStorage;
selfAccessKind = SelfAccessorKind::Peer;
break;
}
}
// If the base is not 'self', default get access to nonmutating and set access to mutating.
bool getterMutatesBase = selfDecl && storage->isGetterMutating();
bool setterMutatesBase = !selfDecl || storage->isSetterMutating();
// If we're not accessing via a property wrapper, we don't need to adjust
// the mutability.
if (target == TargetImpl::Wrapper || target == TargetImpl::WrapperStorage) {
auto var = cast<VarDecl>(accessor->getStorage());
auto mutability = var->getPropertyWrapperMutability();
// Only adjust mutability if it's possible to mutate the base.
if (mutability && !var->isStatic() &&
!(selfDecl && selfTypeForAccess->hasReferenceSemantics())) {
getterMutatesBase = (mutability->Getter == PropertyWrapperMutability::Mutating);
setterMutatesBase = (mutability->Setter == PropertyWrapperMutability::Mutating);
}
}
// If the accessor is mutating, then the base should be referred as an l-value
bool isBaseLValue = (getterMutatesBase && isUsedForGetAccess) ||
(setterMutatesBase && isUsedForSetAccess);
if (!selfDecl) {
assert(target != TargetImpl::Super);
auto *storageDRE = new (ctx) DeclRefExpr(storage, DeclNameLoc(),
/*IsImplicit=*/true, semantics);
auto type = storage->getValueInterfaceType().subst(subs);
if (isBaseLValue)
type = LValueType::get(type);
storageDRE->setType(type);
return finish(storageDRE);
}
// Build self
Expr *selfDRE = buildSelfReference(selfDecl, selfAccessKind, isBaseLValue,
/*convertTy*/ selfTypeForAccess);
if (isBaseLValue)
selfTypeForAccess = LValueType::get(selfTypeForAccess);
if (!selfDRE->getType()->isEqual(selfTypeForAccess)) {
assert(selfAccessKind == SelfAccessorKind::Super);
selfDRE = new (ctx) DerivedToBaseExpr(selfDRE, selfTypeForAccess);
}
// Build self.member or equivalent
Expr *lookupExpr;