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ProtocolConformance.cpp
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ProtocolConformance.cpp
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//===--- ProtocolConformance.cpp - AST Protocol Conformance ---------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2020 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 the protocol conformance data structures.
//
//===----------------------------------------------------------------------===//
#include "swift/AST/ProtocolConformance.h"
#include "ConformanceLookupTable.h"
#include "swift/AST/ASTContext.h"
#include "swift/AST/Availability.h"
#include "swift/AST/Decl.h"
#include "swift/AST/FileUnit.h"
#include "swift/AST/GenericEnvironment.h"
#include "swift/AST/LazyResolver.h"
#include "swift/AST/Module.h"
#include "swift/AST/TypeCheckRequests.h"
#include "swift/AST/TypeWalker.h"
#include "swift/AST/Types.h"
#include "swift/AST/TypeCheckRequests.h"
#include "swift/Basic/Statistic.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/TinyPtrVector.h"
#include "llvm/Support/PrettyStackTrace.h"
#include "llvm/Support/SaveAndRestore.h"
#define DEBUG_TYPE "AST"
STATISTIC(NumConformanceLookupTables, "# of conformance lookup tables built");
using namespace swift;
Witness::Witness(ValueDecl *decl, SubstitutionMap substitutions,
GenericEnvironment *syntheticEnv,
SubstitutionMap reqToSynthesizedEnvSubs) {
if (!syntheticEnv && substitutions.empty() &&
reqToSynthesizedEnvSubs.empty()) {
storage = decl;
return;
}
auto &ctx = decl->getASTContext();
auto declRef = ConcreteDeclRef(decl, substitutions);
auto storedMem = ctx.Allocate(sizeof(StoredWitness), alignof(StoredWitness));
auto stored = new (storedMem) StoredWitness{declRef, syntheticEnv,
reqToSynthesizedEnvSubs};
storage = stored;
}
void Witness::dump() const { dump(llvm::errs()); }
void Witness::dump(llvm::raw_ostream &out) const {
// FIXME: Implement!
}
ProtocolConformanceRef::ProtocolConformanceRef(ProtocolDecl *protocol,
ProtocolConformance *conf) {
assert(protocol != nullptr &&
"cannot construct ProtocolConformanceRef with null protocol");
if (conf) {
assert(protocol == conf->getProtocol() && "protocol conformance mismatch");
Union = conf;
} else {
Union = protocol;
}
}
ProtocolDecl *ProtocolConformanceRef::getRequirement() const {
assert(!isInvalid());
if (isConcrete()) {
return getConcrete()->getProtocol();
} else {
return getAbstract();
}
}
ProtocolConformanceRef
ProtocolConformanceRef::subst(Type origType,
SubstitutionMap subMap,
SubstOptions options) const {
return subst(origType,
QuerySubstitutionMap{subMap},
LookUpConformanceInSubstitutionMap(subMap),
options);
}
ProtocolConformanceRef
ProtocolConformanceRef::subst(Type origType,
TypeSubstitutionFn subs,
LookupConformanceFn conformances,
SubstOptions options) const {
if (isInvalid())
return *this;
// If we have a concrete conformance, we need to substitute the
// conformance to apply to the new type.
if (isConcrete())
return ProtocolConformanceRef(getConcrete()->subst(subs, conformances,
options));
// If the type is an opaque archetype, the conformance will remain abstract,
// unless we're specifically substituting opaque types.
if (auto origArchetype = origType->getAs<ArchetypeType>()) {
if (!options.contains(SubstFlags::SubstituteOpaqueArchetypes)
&& isa<OpaqueTypeArchetypeType>(origArchetype->getRoot())) {
return *this;
}
}
// Otherwise, compute the substituted type.
auto substType = origType.subst(subs, conformances, options);
auto *proto = getRequirement();
// If the type is an existential, it must be self-conforming.
if (substType->isExistentialType()) {
auto optConformance =
proto->getModuleContext()->lookupExistentialConformance(substType,
proto);
if (optConformance)
return optConformance;
return ProtocolConformanceRef::forInvalid();
}
// Check the conformance map.
return conformances(origType->getCanonicalType(), substType, proto);
}
ProtocolConformanceRef ProtocolConformanceRef::mapConformanceOutOfContext() const {
if (!isConcrete())
return *this;
auto *concrete = getConcrete()->subst(
[](SubstitutableType *type) -> Type {
if (auto *archetypeType = type->getAs<ArchetypeType>())
return archetypeType->getInterfaceType();
return type;
},
MakeAbstractConformanceForGenericType());
return ProtocolConformanceRef(concrete);
}
Type
ProtocolConformanceRef::getTypeWitnessByName(Type type, Identifier name) const {
assert(!isInvalid());
// Find the named requirement.
ProtocolDecl *proto = getRequirement();
auto *assocType = proto->getAssociatedType(name);
// FIXME: Shouldn't this be a hard error?
if (!assocType)
return ErrorType::get(proto->getASTContext());
return assocType->getDeclaredInterfaceType().subst(
SubstitutionMap::getProtocolSubstitutions(proto, type, *this));
}
ConcreteDeclRef
ProtocolConformanceRef::getWitnessByName(Type type, DeclName name) const {
// Find the named requirement.
auto *proto = getRequirement();
auto *requirement = proto->getSingleRequirement(name);
if (requirement == nullptr)
return ConcreteDeclRef();
// For a type with dependent conformance, just return the requirement from
// the protocol. There are no protocol conformance tables.
if (!isConcrete()) {
auto subs = SubstitutionMap::getProtocolSubstitutions(proto, type, *this);
return ConcreteDeclRef(requirement, subs);
}
return getConcrete()->getWitnessDeclRef(requirement);
}
#define CONFORMANCE_SUBCLASS_DISPATCH(Method, Args) \
switch (getKind()) { \
case ProtocolConformanceKind::Normal: \
return cast<NormalProtocolConformance>(this)->Method Args; \
case ProtocolConformanceKind::Self: \
return cast<SelfProtocolConformance>(this)->Method Args; \
case ProtocolConformanceKind::Specialized: \
return cast<SpecializedProtocolConformance>(this)->Method Args; \
case ProtocolConformanceKind::Inherited: \
return cast<InheritedProtocolConformance>(this)->Method Args; \
case ProtocolConformanceKind::Builtin: \
static_assert(&ProtocolConformance::Method != \
&BuiltinProtocolConformance::Method, \
"Must override BuiltinProtocolConformance::" #Method); \
return cast<BuiltinProtocolConformance>(this)->Method Args; \
} \
llvm_unreachable("bad ProtocolConformanceKind");
#define ROOT_CONFORMANCE_SUBCLASS_DISPATCH(Method, Args) \
switch (getKind()) { \
case ProtocolConformanceKind::Normal: \
return cast<NormalProtocolConformance>(this)->Method Args; \
case ProtocolConformanceKind::Self: \
return cast<SelfProtocolConformance>(this)->Method Args; \
case ProtocolConformanceKind::Specialized: \
case ProtocolConformanceKind::Inherited: \
case ProtocolConformanceKind::Builtin: \
llvm_unreachable("not a root conformance"); \
} \
llvm_unreachable("bad ProtocolConformanceKind");
/// Get the protocol being conformed to.
ProtocolDecl *ProtocolConformance::getProtocol() const {
CONFORMANCE_SUBCLASS_DISPATCH(getProtocol, ())
}
DeclContext *ProtocolConformance::getDeclContext() const {
CONFORMANCE_SUBCLASS_DISPATCH(getDeclContext, ())
}
/// Retrieve the state of this conformance.
ProtocolConformanceState ProtocolConformance::getState() const {
CONFORMANCE_SUBCLASS_DISPATCH(getState, ())
}
ConformanceEntryKind ProtocolConformance::getSourceKind() const {
CONFORMANCE_SUBCLASS_DISPATCH(getSourceKind, ())
}
NormalProtocolConformance *ProtocolConformance::getImplyingConformance() const {
CONFORMANCE_SUBCLASS_DISPATCH(getImplyingConformance, ())
}
bool
ProtocolConformance::hasTypeWitness(AssociatedTypeDecl *assocType) const {
CONFORMANCE_SUBCLASS_DISPATCH(hasTypeWitness, (assocType));
}
TypeWitnessAndDecl
ProtocolConformance::getTypeWitnessAndDecl(AssociatedTypeDecl *assocType,
SubstOptions options) const {
CONFORMANCE_SUBCLASS_DISPATCH(getTypeWitnessAndDecl,
(assocType, options))
}
Type ProtocolConformance::getTypeWitness(AssociatedTypeDecl *assocType,
SubstOptions options) const {
return getTypeWitnessAndDecl(assocType, options).getWitnessType();
}
ConcreteDeclRef
ProtocolConformance::getWitnessDeclRef(ValueDecl *requirement) const {
CONFORMANCE_SUBCLASS_DISPATCH(getWitnessDeclRef, (requirement))
}
ValueDecl *ProtocolConformance::getWitnessDecl(ValueDecl *requirement) const {
switch (getKind()) {
case ProtocolConformanceKind::Normal:
return cast<NormalProtocolConformance>(this)->getWitness(requirement)
.getDecl();
case ProtocolConformanceKind::Self:
return cast<SelfProtocolConformance>(this)->getWitness(requirement)
.getDecl();
case ProtocolConformanceKind::Inherited:
return cast<InheritedProtocolConformance>(this)
->getInheritedConformance()->getWitnessDecl(requirement);
case ProtocolConformanceKind::Specialized:
return cast<SpecializedProtocolConformance>(this)
->getGenericConformance()->getWitnessDecl(requirement);
case ProtocolConformanceKind::Builtin:
return requirement;
}
llvm_unreachable("unhandled kind");
}
/// Determine whether the witness for the given requirement
/// is either the default definition or was otherwise deduced.
bool ProtocolConformance::
usesDefaultDefinition(AssociatedTypeDecl *requirement) const {
CONFORMANCE_SUBCLASS_DISPATCH(usesDefaultDefinition, (requirement))
}
GenericEnvironment *ProtocolConformance::getGenericEnvironment() const {
switch (getKind()) {
case ProtocolConformanceKind::Inherited:
case ProtocolConformanceKind::Normal:
case ProtocolConformanceKind::Self:
// If we have a normal or inherited protocol conformance, look for its
// generic parameters.
return getDeclContext()->getGenericEnvironmentOfContext();
case ProtocolConformanceKind::Specialized:
case ProtocolConformanceKind::Builtin:
// If we have a specialized protocol conformance, since we do not support
// currently partial specialization, we know that it cannot have any open
// type variables.
//
// FIXME: We could return a meaningful GenericEnvironment here
return nullptr;
}
llvm_unreachable("Unhandled ProtocolConformanceKind in switch.");
}
GenericSignature ProtocolConformance::getGenericSignature() const {
switch (getKind()) {
case ProtocolConformanceKind::Inherited:
case ProtocolConformanceKind::Normal:
case ProtocolConformanceKind::Self:
// If we have a normal or inherited protocol conformance, look for its
// generic signature.
return getDeclContext()->getGenericSignatureOfContext();
case ProtocolConformanceKind::Builtin:
return cast<BuiltinProtocolConformance>(this)->getGenericSignature();
case ProtocolConformanceKind::Specialized:
// If we have a specialized protocol conformance, since we do not support
// currently partial specialization, we know that it cannot have any open
// type variables.
return nullptr;
}
llvm_unreachable("Unhandled ProtocolConformanceKind in switch.");
}
SubstitutionMap ProtocolConformance::getSubstitutions(ModuleDecl *M) const {
// Walk down to the base NormalProtocolConformance.
SubstitutionMap subMap;
const ProtocolConformance *parent = this;
while (!isa<RootProtocolConformance>(parent)) {
switch (parent->getKind()) {
case ProtocolConformanceKind::Normal:
case ProtocolConformanceKind::Self:
case ProtocolConformanceKind::Builtin:
llvm_unreachable("should have exited the loop?!");
case ProtocolConformanceKind::Inherited:
parent =
cast<InheritedProtocolConformance>(parent)->getInheritedConformance();
break;
case ProtocolConformanceKind::Specialized: {
auto SC = cast<SpecializedProtocolConformance>(parent);
parent = SC->getGenericConformance();
assert(subMap.empty() && "multiple conformance specializations?!");
subMap = SC->getSubstitutionMap();
break;
}
}
}
// Found something; we're done!
if (!subMap.empty())
return subMap;
// If the normal conformance is for a generic type, and we didn't hit a
// specialized conformance, collect the substitutions from the generic type.
// FIXME: The AST should do this for us.
const NormalProtocolConformance *normalC =
dyn_cast<NormalProtocolConformance>(parent);
if (!normalC)
return SubstitutionMap();
if (!normalC->getType()->isSpecialized())
return SubstitutionMap();
auto *DC = normalC->getDeclContext();
return normalC->getType()->getContextSubstitutionMap(M, DC);
}
bool RootProtocolConformance::isInvalid() const {
ROOT_CONFORMANCE_SUBCLASS_DISPATCH(isInvalid, ())
}
SourceLoc RootProtocolConformance::getLoc() const {
ROOT_CONFORMANCE_SUBCLASS_DISPATCH(getLoc, ())
}
bool
RootProtocolConformance::isWeakImported(ModuleDecl *fromModule) const {
auto *dc = getDeclContext();
if (dc->getParentModule() == fromModule)
return false;
// If the protocol is weak imported, so are any conformances to it.
if (getProtocol()->isWeakImported(fromModule))
return true;
// If the conforming type is weak imported, so are any of its conformances.
if (auto *nominal = getType()->getAnyNominal())
if (nominal->isWeakImported(fromModule))
return true;
// If the conformance is declared in an extension with the @_weakLinked
// attribute, it is weak imported.
if (auto *ext = dyn_cast<ExtensionDecl>(dc))
if (ext->isWeakImported(fromModule))
return true;
return false;
}
bool RootProtocolConformance::hasWitness(ValueDecl *requirement) const {
ROOT_CONFORMANCE_SUBCLASS_DISPATCH(hasWitness, (requirement))
}
bool NormalProtocolConformance::isRetroactive() const {
auto module = getDeclContext()->getParentModule();
// If the conformance occurs in the same module as the protocol definition,
// this is not a retroactive conformance.
auto protocolModule = getProtocol()->getDeclContext()->getParentModule();
if (module == protocolModule)
return false;
// If the conformance occurs in the same module as the conforming type
// definition, this is not a retroactive conformance.
if (auto nominal = getType()->getAnyNominal()) {
auto nominalModule = nominal->getParentModule();
// Consider the overlay module to be the "home" of a nominal type
// defined in a Clang module.
if (auto nominalLoadedModule =
dyn_cast<LoadedFile>(nominal->getModuleScopeContext())) {
if (auto overlayModule = nominalLoadedModule->getOverlayModule())
nominalModule = overlayModule;
}
if (module == nominalModule)
return false;
}
// Everything else is retroactive.
return true;
}
bool NormalProtocolConformance::isSynthesizedNonUnique() const {
if (auto *file = dyn_cast<FileUnit>(getDeclContext()->getModuleScopeContext()))
return file->getKind() == FileUnitKind::ClangModule;
return false;
}
bool NormalProtocolConformance::isResilient() const {
// If the type is non-resilient or the module we're in is non-resilient, the
// conformance is non-resilient.
// FIXME: Looking at the type is not the right long-term solution. We need an
// explicit mechanism for declaring conformances as 'fragile', or even
// individual witnesses.
if (!getType()->getAnyNominal()->isResilient())
return false;
return getDeclContext()->getParentModule()->isResilient();
}
Optional<ArrayRef<Requirement>>
ProtocolConformance::getConditionalRequirementsIfAvailable() const {
CONFORMANCE_SUBCLASS_DISPATCH(getConditionalRequirementsIfAvailable, ());
}
ArrayRef<Requirement> ProtocolConformance::getConditionalRequirements() const {
CONFORMANCE_SUBCLASS_DISPATCH(getConditionalRequirements, ());
}
Optional<ArrayRef<Requirement>>
ProtocolConformanceRef::getConditionalRequirementsIfAvailable() const {
if (isConcrete())
return getConcrete()->getConditionalRequirementsIfAvailable();
else
// An abstract conformance is never conditional: any conditionality in the
// concrete types that will eventually pass through this at runtime is
// completely pre-checked and packaged up.
return ArrayRef<Requirement>();
}
ArrayRef<Requirement>
ProtocolConformanceRef::getConditionalRequirements() const {
if (isConcrete())
return getConcrete()->getConditionalRequirements();
else
// An abstract conformance is never conditional, as above.
return {};
}
Optional<ArrayRef<Requirement>>
NormalProtocolConformance::getConditionalRequirementsIfAvailable() const {
const auto &eval = getDeclContext()->getASTContext().evaluator;
if (eval.hasActiveRequest(ConditionalRequirementsRequest{
const_cast<NormalProtocolConformance *>(this)})) {
return None;
}
return getConditionalRequirements();
}
llvm::ArrayRef<Requirement>
NormalProtocolConformance::getConditionalRequirements() const {
const auto ext = dyn_cast<ExtensionDecl>(getDeclContext());
if (ext && ext->isComputingGenericSignature()) {
return {};
}
return evaluateOrDefault(getProtocol()->getASTContext().evaluator,
ConditionalRequirementsRequest{
const_cast<NormalProtocolConformance *>(this)},
{});
}
llvm::ArrayRef<Requirement>
ConditionalRequirementsRequest::evaluate(Evaluator &evaluator,
NormalProtocolConformance *NPC) const {
// A non-extension conformance won't have conditional requirements.
const auto ext = dyn_cast<ExtensionDecl>(NPC->getDeclContext());
if (!ext) {
return {};
}
// If the extension is invalid, it won't ever get a signature, so we
// "succeed" with an empty result instead.
if (ext->isInvalid()) {
return {};
}
// A non-generic type won't have conditional requirements.
const auto typeSig = ext->getExtendedNominal()->getGenericSignature();
if (!typeSig) {
return {};
}
const auto extensionSig = ext->getGenericSignature();
// The extension signature should be a superset of the type signature, meaning
// every thing in the type signature either is included too or is implied by
// something else. The most important bit is having the same type
// parameters. (NB. if/when Swift gets parameterized extensions, this needs to
// change.)
assert(typeSig.getCanonicalSignature().getGenericParams() ==
extensionSig.getCanonicalSignature().getGenericParams());
// Find the requirements in the extension that aren't proved by the original
// type, these are the ones that make the conformance conditional.
const auto unsatReqs = extensionSig->requirementsNotSatisfiedBy(typeSig);
if (unsatReqs.empty())
return {};
return NPC->getProtocol()->getASTContext().AllocateCopy(unsatReqs);
}
void NormalProtocolConformance::setSignatureConformances(
ArrayRef<ProtocolConformanceRef> conformances) {
if (conformances.empty()) {
SignatureConformances = { };
return;
}
auto &ctx = getProtocol()->getASTContext();
SignatureConformances = ctx.AllocateCopy(conformances);
#if !NDEBUG
unsigned idx = 0;
for (const auto &req : getProtocol()->getRequirementSignature()) {
if (req.getKind() == RequirementKind::Conformance) {
assert(!conformances[idx].isConcrete() ||
!conformances[idx].getConcrete()->getType()->hasArchetype() &&
"Should have interface types here");
assert(idx < conformances.size());
assert(conformances[idx].isInvalid() ||
conformances[idx].getRequirement() == req.getProtocolDecl());
++idx;
}
}
assert(idx == conformances.size() && "Too many conformances");
#endif
}
void NormalProtocolConformance::resolveLazyInfo() const {
assert(Loader);
auto *loader = Loader;
auto *mutableThis = const_cast<NormalProtocolConformance *>(this);
mutableThis->Loader = nullptr;
loader->finishNormalConformance(mutableThis, LoaderContextData);
}
void NormalProtocolConformance::setLazyLoader(LazyConformanceLoader *loader,
uint64_t contextData) {
assert(!Loader && "already has a loader");
Loader = loader;
LoaderContextData = contextData;
}
namespace {
class PrettyStackTraceRequirement : public llvm::PrettyStackTraceEntry {
const char *Action;
const ProtocolConformance *Conformance;
ValueDecl *Requirement;
public:
PrettyStackTraceRequirement(const char *action,
const ProtocolConformance *conformance,
ValueDecl *requirement)
: Action(action), Conformance(conformance), Requirement(requirement) { }
void print(llvm::raw_ostream &out) const override {
out << "While " << Action << " requirement ";
Requirement->dumpRef(out);
out << " in conformance ";
Conformance->printName(out);
out << "\n";
}
};
} // end anonymous namespace
bool NormalProtocolConformance::hasTypeWitness(
AssociatedTypeDecl *assocType) const {
if (Loader)
resolveLazyInfo();
auto found = TypeWitnesses.find(assocType);
if (found != TypeWitnesses.end()) {
return !found->getSecond().getWitnessType().isNull();
}
return false;
}
TypeWitnessAndDecl
NormalProtocolConformance::getTypeWitnessAndDecl(AssociatedTypeDecl *assocType,
SubstOptions options) const {
if (Loader)
resolveLazyInfo();
// Check whether we already have a type witness.
auto known = TypeWitnesses.find(assocType);
if (known != TypeWitnesses.end())
return known->second;
// If there is a tentative-type-witness function, use it.
if (options.getTentativeTypeWitness) {
if (Type witnessType =
Type(options.getTentativeTypeWitness(this, assocType)))
return { witnessType, nullptr };
}
// If this conformance is in a state where it is inferring type witnesses but
// we didn't find anything, fail.
if (getState() == ProtocolConformanceState::CheckingTypeWitnesses) {
return { Type(), nullptr };
}
// If the conditional requirements aren't known, we can't properly run
// inference.
if (!getConditionalRequirementsIfAvailable()) {
return TypeWitnessAndDecl();
}
return evaluateOrDefault(
assocType->getASTContext().evaluator,
TypeWitnessRequest{const_cast<NormalProtocolConformance *>(this),
assocType},
TypeWitnessAndDecl());
}
TypeWitnessAndDecl NormalProtocolConformance::getTypeWitnessUncached(
AssociatedTypeDecl *requirement) const {
auto entry = TypeWitnesses.find(requirement);
if (entry == TypeWitnesses.end()) {
return TypeWitnessAndDecl();
}
return entry->second;
}
void NormalProtocolConformance::setTypeWitness(AssociatedTypeDecl *assocType,
Type type,
TypeDecl *typeDecl) const {
assert(getProtocol() == cast<ProtocolDecl>(assocType->getDeclContext()) &&
"associated type in wrong protocol");
assert((TypeWitnesses.count(assocType) == 0 ||
TypeWitnesses[assocType].getWitnessType().isNull()) &&
"Type witness already known");
assert((!isComplete() || isInvalid()) && "Conformance already complete?");
assert(!type->hasArchetype() && "type witnesses must be interface types");
TypeWitnesses[assocType] = {type, typeDecl};
}
Type ProtocolConformance::getAssociatedType(Type assocType) const {
assert(assocType->isTypeParameter() &&
"associated type must be a type parameter");
ProtocolConformanceRef ref(const_cast<ProtocolConformance*>(this));
return ref.getAssociatedType(getType(), assocType);
}
Type ProtocolConformanceRef::getAssociatedType(Type conformingType,
Type assocType) const {
assert(!isConcrete() || getConcrete()->getType()->isEqual(conformingType));
auto type = assocType->getCanonicalType();
auto proto = getRequirement();
// Fast path for generic parameters.
if (isa<GenericTypeParamType>(type)) {
assert(type->isEqual(proto->getSelfInterfaceType()) &&
"type parameter in protocol was not Self");
return conformingType;
}
// Fast path for dependent member types on 'Self' of our associated types.
auto memberType = cast<DependentMemberType>(type);
if (memberType.getBase()->isEqual(proto->getSelfInterfaceType()) &&
memberType->getAssocType()->getProtocol() == proto &&
isConcrete())
return getConcrete()->getTypeWitness(memberType->getAssocType());
// General case: consult the substitution map.
auto substMap =
SubstitutionMap::getProtocolSubstitutions(proto, conformingType, *this);
return type.subst(substMap);
}
ProtocolConformanceRef
ProtocolConformanceRef::getAssociatedConformance(Type conformingType,
Type assocType,
ProtocolDecl *protocol) const {
// If this is a concrete conformance, look up the associated conformance.
if (isConcrete()) {
auto conformance = getConcrete();
assert(conformance->getType()->isEqual(conformingType));
return conformance->getAssociatedConformance(assocType, protocol);
}
// Otherwise, apply the substitution {self -> conformingType}
// to the abstract conformance requirement laid upon the dependent type
// by the protocol.
auto subMap =
SubstitutionMap::getProtocolSubstitutions(getRequirement(),
conformingType, *this);
auto abstractConf = ProtocolConformanceRef(protocol);
return abstractConf.subst(assocType, subMap);
}
ProtocolConformanceRef
ProtocolConformance::getAssociatedConformance(Type assocType,
ProtocolDecl *protocol) const {
CONFORMANCE_SUBCLASS_DISPATCH(getAssociatedConformance,
(assocType, protocol))
}
ProtocolConformanceRef
NormalProtocolConformance::getAssociatedConformance(Type assocType,
ProtocolDecl *protocol) const {
assert(assocType->isTypeParameter() &&
"associated type must be a type parameter");
// Fill in the signature conformances, if we haven't done so yet.
if (getSignatureConformances().empty()) {
const_cast<NormalProtocolConformance *>(this)->finishSignatureConformances();
}
assert(!getSignatureConformances().empty() &&
"signature conformances not yet computed");
unsigned conformanceIndex = 0;
for (const auto &reqt : getProtocol()->getRequirementSignature()) {
if (reqt.getKind() == RequirementKind::Conformance) {
// Is this the conformance we're looking for?
if (reqt.getFirstType()->isEqual(assocType) &&
reqt.getProtocolDecl() == protocol)
return getSignatureConformances()[conformanceIndex];
++conformanceIndex;
}
}
llvm_unreachable(
"requested conformance was not a direct requirement of the protocol");
}
/// A stripped-down version of Type::subst that only works on the protocol
/// Self type wrapped in zero or more DependentMemberTypes.
static Type
recursivelySubstituteBaseType(ModuleDecl *module,
NormalProtocolConformance *conformance,
DependentMemberType *depMemTy) {
Type origBase = depMemTy->getBase();
// Recursive case.
if (auto *depBase = origBase->getAs<DependentMemberType>()) {
Type substBase = recursivelySubstituteBaseType(
module, conformance, depBase);
return depMemTy->substBaseType(module, substBase);
}
// Base case. The associated type's protocol should be either the
// conformance protocol or an inherited protocol.
auto *reqProto = depMemTy->getAssocType()->getProtocol();
assert(origBase->isEqual(reqProto->getSelfInterfaceType()));
ProtocolConformance *reqConformance = conformance;
// If we have an inherited protocol just look up the conformance.
if (reqProto != conformance->getProtocol()) {
reqConformance = module->lookupConformance(conformance->getType(), reqProto)
.getConcrete();
}
return reqConformance->getTypeWitness(depMemTy->getAssocType());
}
/// Collect conformances for the requirement signature.
void NormalProtocolConformance::finishSignatureConformances() {
if (!SignatureConformances.empty())
return;
auto *proto = getProtocol();
auto reqSig = proto->getRequirementSignature();
if (reqSig.empty())
return;
SmallVector<ProtocolConformanceRef, 4> reqConformances;
for (const auto &req : reqSig) {
if (req.getKind() != RequirementKind::Conformance)
continue;
ModuleDecl *module = getDeclContext()->getParentModule();
Type substTy;
auto origTy = req.getFirstType();
if (origTy->isEqual(proto->getSelfInterfaceType())) {
substTy = getType();
} else {
auto *depMemTy = origTy->castTo<DependentMemberType>();
substTy = recursivelySubstituteBaseType(module, this, depMemTy);
}
auto reqProto = req.getProtocolDecl();
// Looking up a conformance for a contextual type and mapping the
// conformance context produces a more accurate result than looking
// up a conformance from an interface type.
//
// This can happen if the conformance has an associated conformance
// depending on an associated type that is made concrete in a
// refining protocol.
//
// That is, the conformance of an interface type G<T> : P really
// depends on the generic signature of the current context, because
// performing the lookup in a "more" constrained extension than the
// one where the conformance was defined must produce concrete
// conformances.
//
// FIXME: Eliminate this, perhaps by adding a variant of
// lookupConformance() taking a generic signature.
if (substTy->hasTypeParameter())
substTy = getDeclContext()->mapTypeIntoContext(substTy);
reqConformances.push_back(module->lookupConformance(substTy, reqProto)
.mapConformanceOutOfContext());
}
setSignatureConformances(reqConformances);
}
Witness RootProtocolConformance::getWitness(ValueDecl *requirement) const {
ROOT_CONFORMANCE_SUBCLASS_DISPATCH(getWitness, (requirement))
}
/// Retrieve the value witness corresponding to the given requirement.
Witness NormalProtocolConformance::getWitness(ValueDecl *requirement) const {
assert(!isa<AssociatedTypeDecl>(requirement) && "Request type witness");
assert(requirement->isProtocolRequirement() && "Not a requirement");
if (Loader)
resolveLazyInfo();
return evaluateOrDefault(
requirement->getASTContext().evaluator,
ValueWitnessRequest{const_cast<NormalProtocolConformance *>(this),
requirement},
Witness());
}
Witness
NormalProtocolConformance::getWitnessUncached(ValueDecl *requirement) const {
auto entry = Mapping.find(requirement);
if (entry == Mapping.end()) {
return Witness();
}
return entry->second;
}
Witness SelfProtocolConformance::getWitness(ValueDecl *requirement) const {
return Witness(requirement, SubstitutionMap(), nullptr, SubstitutionMap());
}
ConcreteDeclRef
RootProtocolConformance::getWitnessDeclRef(ValueDecl *requirement) const {
if (auto witness = getWitness(requirement)) {
auto *witnessDecl = witness.getDecl();
// If the witness is generic, you have to call getWitness() and build
// your own substitutions in terms of the synthetic environment.
if (auto *witnessDC = dyn_cast<DeclContext>(witnessDecl))
assert(!witnessDC->isInnermostContextGeneric());
// If the witness is not generic, use type substitutions from the
// witness's parent. Don't use witness.getSubstitutions(), which
// are written in terms of the synthetic environment.
auto subs =
getType()->getContextSubstitutionMap(getDeclContext()->getParentModule(),
witnessDecl->getDeclContext());
return ConcreteDeclRef(witness.getDecl(), subs);
}
return ConcreteDeclRef();
}
void NormalProtocolConformance::setWitness(ValueDecl *requirement,
Witness witness) const {
assert(!isa<AssociatedTypeDecl>(requirement) && "Request type witness");
assert(getProtocol() == cast<ProtocolDecl>(requirement->getDeclContext()) &&
"requirement in wrong protocol");
assert(Mapping.count(requirement) == 0 && "Witness already known");
assert((!isComplete() || isInvalid() ||
requirement->getAttrs().hasAttribute<OptionalAttr>() ||
requirement->getAttrs().isUnavailable(
requirement->getASTContext())) &&
"Conformance already complete?");
Mapping[requirement] = witness;
}
SpecializedProtocolConformance::SpecializedProtocolConformance(
Type conformingType,
ProtocolConformance *genericConformance,
SubstitutionMap substitutions)
: ProtocolConformance(ProtocolConformanceKind::Specialized, conformingType),
GenericConformance(genericConformance),
GenericSubstitutions(substitutions)
{
assert(genericConformance->getKind() != ProtocolConformanceKind::Specialized);
}
void SpecializedProtocolConformance::computeConditionalRequirements() const {
// already computed?
if (ConditionalRequirements)
return;
auto parentCondReqs =
GenericConformance->getConditionalRequirementsIfAvailable();
if (!parentCondReqs)
return;
if (!parentCondReqs->empty()) {
// Substitute the conditional requirements so that they're phrased in
// terms of the specialized types, not the conformance-declaring decl's
// types.
ModuleDecl *module;
SubstitutionMap subMap;
if (auto nominal = GenericConformance->getType()->getAnyNominal()) {
module = nominal->getModuleContext();
subMap = getType()->getContextSubstitutionMap(module, nominal);
} else {
module = getProtocol()->getModuleContext();
subMap = getSubstitutionMap();
}
SmallVector<Requirement, 4> newReqs;
for (auto oldReq : *parentCondReqs) {
if (auto newReq = oldReq.subst(QuerySubstitutionMap{subMap},
LookUpConformanceInModule(module)))
newReqs.push_back(*newReq);
}
auto &ctxt = getProtocol()->getASTContext();
ConditionalRequirements = ctxt.AllocateCopy(newReqs);
} else {
ConditionalRequirements = ArrayRef<Requirement>();
}
}
bool SpecializedProtocolConformance::hasTypeWitness(
AssociatedTypeDecl *assocType) const {
return TypeWitnesses.find(assocType) != TypeWitnesses.end() ||
GenericConformance->hasTypeWitness(assocType);
}
TypeWitnessAndDecl
SpecializedProtocolConformance::getTypeWitnessAndDecl(
AssociatedTypeDecl *assocType,
SubstOptions options) const {
assert(getProtocol() == cast<ProtocolDecl>(assocType->getDeclContext()) &&
"associated type in wrong protocol");
// If we've already created this type witness, return it.
auto known = TypeWitnesses.find(assocType);
if (known != TypeWitnesses.end()) {
return known->second;
}