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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 ProtocolConformance class hierarchy.
//
//===----------------------------------------------------------------------===//
#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/DistributedDecl.h"
#include "swift/AST/FileUnit.h"
#include "swift/AST/GenericEnvironment.h"
#include "swift/AST/InFlightSubstitution.h"
#include "swift/AST/LazyResolver.h"
#include "swift/AST/Module.h"
#include "swift/AST/NameLookup.h"
#include "swift/AST/PackConformance.h"
#include "swift/AST/TypeCheckRequests.h"
#include "swift/AST/Types.h"
#include "swift/Basic/Statistic.h"
#include "llvm/ADT/Statistic.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,
GenericSignature witnessThunkSig,
SubstitutionMap reqToWitnessThunkSigSubs,
GenericSignature derivativeGenSig,
std::optional<ActorIsolation> enterIsolation) {
if (!witnessThunkSig && substitutions.empty() &&
reqToWitnessThunkSigSubs.empty() && !enterIsolation) {
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, witnessThunkSig,
reqToWitnessThunkSigSubs,
derivativeGenSig, enterIsolation};
storage = stored;
}
Witness Witness::withEnterIsolation(ActorIsolation enterIsolation) const {
return Witness(getDecl(), getSubstitutions(), getWitnessThunkSignature(),
getRequirementToWitnessThunkSubs(),
getDerivativeGenericSignature(), enterIsolation);
}
void Witness::dump() const { dump(llvm::errs()); }
void Witness::dump(llvm::raw_ostream &out) const {
out << "Witness: ";
if (auto decl = this->getDecl()) {
decl->dumpRef(out);
out << "\n";
} else {
out << "<no decl>\n";
}
}
#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: \
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::Builtin: \
return cast<BuiltinProtocolConformance>(this)->Method Args; \
case ProtocolConformanceKind::Specialized: \
case ProtocolConformanceKind::Inherited: \
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))
}
bool ProtocolConformance::isRetroactive() const {
auto extensionModule = getDeclContext()->getParentModule();
auto protocolModule = getProtocol()->getParentModule();
if (extensionModule->isSameModuleLookingThroughOverlays(protocolModule)) {
return false;
}
auto conformingTypeDecl =
ConformingType->getNominalOrBoundGenericNominal();
if (conformingTypeDecl) {
auto conformingTypeModule = conformingTypeDecl->getParentModule();
if (extensionModule->
isSameModuleLookingThroughOverlays(conformingTypeModule)) {
return false;
}
}
return true;
}
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::getSubstitutionMap() const {
CONFORMANCE_SUBCLASS_DISPATCH(getSubstitutionMap, ())
}
SubstitutionMap RootProtocolConformance::getSubstitutionMap() const {
if (auto genericSig = getGenericSignature())
return genericSig->getIdentitySubstitutionMap();
return SubstitutionMap();
}
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 RootProtocolConformance::isSynthesized() const {
if (auto normal = dyn_cast<NormalProtocolConformance>(this))
return normal->isSynthesizedNonUnique() || normal->isConformanceOfProtocol();
return false;
}
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 {
// Check if the conformance was synthesized by the ClangImporter.
if (auto *file = dyn_cast<FileUnit>(getDeclContext()->getModuleScopeContext()))
return file->getKind() == FileUnitKind::ClangModule;
return false;
}
bool NormalProtocolConformance::isConformanceOfProtocol() const {
return getDeclContext()->getSelfProtocolDecl() != nullptr;
}
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 (!getDeclContext()->getSelfNominalTypeDecl()->isResilient())
return false;
return getDeclContext()->getParentModule()->isResilient();
}
std::optional<ArrayRef<Requirement>>
ProtocolConformance::getConditionalRequirementsIfAvailable() const {
CONFORMANCE_SUBCLASS_DISPATCH(getConditionalRequirementsIfAvailable, ());
}
ArrayRef<Requirement> ProtocolConformance::getConditionalRequirements() const {
CONFORMANCE_SUBCLASS_DISPATCH(getConditionalRequirements, ());
}
std::optional<ArrayRef<Requirement>>
NormalProtocolConformance::getConditionalRequirementsIfAvailable() const {
const auto &eval = getDeclContext()->getASTContext().evaluator;
if (eval.hasActiveRequest(ConditionalRequirementsRequest{
const_cast<NormalProtocolConformance *>(this)})) {
return std::nullopt;
}
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::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.
//
// FIXME: This is unsound, because we may not have diagnosed anything but
// still end up with an ErrorType in the AST.
if (getDeclContext()->getASTContext().evaluator.hasActiveRequest(
ResolveTypeWitnessesRequest{
const_cast<NormalProtocolConformance *>(this)})) {
return { Type(), nullptr };
}
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);
}
ProtocolConformanceRef
ProtocolConformance::getAssociatedConformance(Type assocType,
ProtocolDecl *protocol) const {
CONFORMANCE_SUBCLASS_DISPATCH(getAssociatedConformance,
(assocType, protocol))
}
ProtocolConformanceRef
NormalProtocolConformance::getAssociatedConformance(Type assocType,
ProtocolDecl *protocol) const {
if (Loader)
resolveLazyInfo();
assert(assocType->isTypeParameter() &&
"associated type must be a type parameter");
std::optional<ProtocolConformanceRef> result;
auto &ctx = getDeclContext()->getASTContext();
forEachAssociatedConformance(
[&](Type t, ProtocolDecl *p, unsigned index) {
if (t->isEqual(assocType) && p == protocol) {
// Not strictly necessary, but avoids a bit of request evaluator
// overhead in the happy case.
if (hasComputedAssociatedConformances()) {
result = AssociatedConformances[index];
if (result)
return true;
}
result = evaluateOrDefault(ctx.evaluator,
AssociatedConformanceRequest{
const_cast<NormalProtocolConformance *>(this),
t->getCanonicalType(), p, index
}, ProtocolConformanceRef::forInvalid());
return true;
}
return false;
});
assert(result && "Subject type must be exactly equal to left-hand side of a"
"conformance requirement in protocol requirement signature");
return *result;
}
/// Allocate the backing array if needed, computing its size from the
///protocol's requirement signature.
void NormalProtocolConformance::createAssociatedConformanceArray() {
if (hasComputedAssociatedConformances())
return;
setHasComputedAssociatedConformances();
auto *proto = getProtocol();
unsigned count = 0;
for (auto req : proto->getRequirementSignature().getRequirements()) {
if (req.getKind() == RequirementKind::Conformance)
++count;
}
auto &ctx = proto->getASTContext();
AssociatedConformances =
ctx.Allocate<std::optional<ProtocolConformanceRef>>(count);
}
std::optional<ProtocolConformanceRef>
NormalProtocolConformance::getAssociatedConformance(unsigned index) const {
if (!hasComputedAssociatedConformances())
return std::nullopt;
return AssociatedConformances[index];
}
void NormalProtocolConformance::setAssociatedConformance(
unsigned index, ProtocolConformanceRef assocConf) {
createAssociatedConformanceArray();
assert(!AssociatedConformances[index]);
AssociatedConformances[index] = assocConf;
}
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(),
GenericSignature(), std::nullopt);
}
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 witness thunk signature.
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 witness thunk signature.
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() ||
// TODO(distributed): properly handle isComplete() for distributed
// funcs; there seems to be a problem that we mark completed, but
// afterwards will record the thunk witness;
(dyn_cast<FuncDecl>(requirement)
? (dyn_cast<FuncDecl>(requirement)->isDistributed() ||
dyn_cast<FuncDecl>(requirement)->isDistributedThunk())
: false) ||
requirement->getAttrs().hasAttribute<OptionalAttr>() ||
requirement->getAttrs().isUnavailable(
requirement->getASTContext())) &&
"Conformance already complete?");
Mapping[requirement] = witness;
}
void NormalProtocolConformance::overrideWitness(ValueDecl *requirement,
Witness witness) {
assert(Mapping.count(requirement) == 1 && "Witness not known");
Mapping[requirement] = witness;
}
void NormalProtocolConformance::resolveValueWitnesses() const {
auto mutableThis = const_cast<NormalProtocolConformance *>(this);
evaluateOrDefault(getProtocol()->getASTContext().evaluator,
ResolveValueWitnessesRequest{mutableThis},
evaluator::SideEffect());
}
SpecializedProtocolConformance::SpecializedProtocolConformance(
Type conformingType,
NormalProtocolConformance *genericConformance,
SubstitutionMap substitutions)
: ProtocolConformance(ProtocolConformanceKind::Specialized, conformingType),
GenericConformance(genericConformance),
GenericSubstitutions(substitutions) {}
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) {
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 computed this type witness, return it.
auto known = TypeWitnesses.find(assocType);
if (known != TypeWitnesses.end()) {
return known->second;
}
// Otherwise, perform substitutions to compute this witness.
auto genericWitnessAndDecl
= GenericConformance->getTypeWitnessAndDecl(assocType, options);
auto genericWitness = genericWitnessAndDecl.getWitnessType();
if (!genericWitness)
return { Type(), nullptr };
auto *typeDecl = genericWitnessAndDecl.getWitnessDecl();
auto substitutionMap = getSubstitutionMap();
auto specializedType = genericWitness.subst(substitutionMap, options);
if (specializedType->hasError()) {
if (options.getTentativeTypeWitness)
return { Type(), nullptr };
specializedType = ErrorType::get(genericWitness);
}
// Cache the result.
auto specializedWitnessAndDecl = TypeWitnessAndDecl{specializedType, typeDecl};
if (!options.getTentativeTypeWitness && !specializedType->hasError())
TypeWitnesses[assocType] = specializedWitnessAndDecl;
return specializedWitnessAndDecl;
}
ProtocolConformanceRef
SpecializedProtocolConformance::getAssociatedConformance(Type assocType,
ProtocolDecl *protocol) const {
ProtocolConformanceRef conformance =
GenericConformance->getAssociatedConformance(assocType, protocol);
auto subMap = getSubstitutionMap();
Type origType =
(conformance.isConcrete()
? conformance.getConcrete()->getType()
: GenericConformance->getAssociatedType(assocType));
return conformance.subst(origType, subMap);
}
ConcreteDeclRef
SpecializedProtocolConformance::getWitnessDeclRef(
ValueDecl *requirement) const {
auto baseWitness = GenericConformance->getWitnessDeclRef(requirement);
if (!baseWitness || !baseWitness.isSpecialized())
return baseWitness;
auto specializationMap = getSubstitutionMap();
auto witnessDecl = baseWitness.getDecl();
auto witnessMap = baseWitness.getSubstitutions();
auto combinedMap = witnessMap.subst(specializationMap);
return ConcreteDeclRef(witnessDecl, combinedMap);
}
ProtocolConformanceRef
InheritedProtocolConformance::getAssociatedConformance(Type assocType,
ProtocolDecl *protocol) const {
auto underlying =
InheritedConformance->getAssociatedConformance(assocType, protocol);
// If the conformance is for Self, return an inherited conformance.
if (underlying.isConcrete() &&
assocType->isEqual(getProtocol()->getSelfInterfaceType())) {
auto subclassType = getType();
ASTContext &ctx = subclassType->getASTContext();
return ProtocolConformanceRef(
ctx.getInheritedConformance(subclassType,
underlying.getConcrete()));
}
return underlying;
}
ConcreteDeclRef
InheritedProtocolConformance::getWitnessDeclRef(ValueDecl *requirement) const {
// FIXME: substitutions?
return InheritedConformance->getWitnessDeclRef(requirement);
}
const NormalProtocolConformance *
ProtocolConformance::getRootNormalConformance() const {
// This is an unsafe cast; remove this entire method.
return cast<NormalProtocolConformance>(getRootConformance());
}
const RootProtocolConformance *
ProtocolConformance::getRootConformance() const {
const ProtocolConformance *C = this;
if (auto *inheritedC = dyn_cast<InheritedProtocolConformance>(C))
C = inheritedC->getInheritedConformance();
if (auto *specializedC = dyn_cast<SpecializedProtocolConformance>(C))
return specializedC->getGenericConformance();
return cast<RootProtocolConformance>(C);
}
bool ProtocolConformance::isVisibleFrom(const DeclContext *dc) const {
// FIXME: Implement me!
return true;
}
ProtocolConformanceRef
ProtocolConformance::subst(SubstitutionMap subMap,
SubstOptions options) const {
InFlightSubstitutionViaSubMap IFS(subMap, options);
return subst(IFS);
}
ProtocolConformanceRef
ProtocolConformance::subst(TypeSubstitutionFn subs,
LookupConformanceFn conformances,
SubstOptions options) const {
InFlightSubstitution IFS(subs, conformances, options);
return subst(IFS);
}
/// Check if the replacement is a one-element pack with a scalar type.
static bool isVanishingTupleConformance(
NormalProtocolConformance *generic,
SubstitutionMap substitutions) {
if (!isa<BuiltinTupleDecl>(generic->getDeclContext()->getSelfNominalTypeDecl()))
return false;
auto replacementTypes = substitutions.getReplacementTypes();
assert(replacementTypes.size() == 1);
auto packType = replacementTypes[0]->castTo<PackType>();
return (packType->getNumElements() == 1 &&
!packType->getElementTypes()[0]->is<PackExpansionType>());
}
/// Don't form a tuple conformance if the substituted type is unwrapped
/// from a one-element tuple.
///
/// That is, [(repeat each T): P] ⊗ {each T := Pack{U};
/// [each T: P]: Pack{ [U: P] }}
/// => [U: P]
static ProtocolConformanceRef unwrapVanishingTupleConformance(
SubstitutionMap substitutions) {
auto conformances = substitutions.getConformances();
assert(conformances.size() == 1);
assert(conformances[0].isPack());
auto packConformance = conformances[0].getPack();
assert(packConformance->getPatternConformances().size() == 1);
return packConformance->getPatternConformances()[0];
}
ProtocolConformanceRef
ProtocolConformance::subst(InFlightSubstitution &IFS) const {
auto *mutableThis = const_cast<ProtocolConformance *>(this);
switch (getKind()) {
case ProtocolConformanceKind::Normal: {
auto origType = getType();
if (!origType->hasTypeParameter() &&
!origType->hasArchetype())
return ProtocolConformanceRef(mutableThis);
auto substType = origType.subst(IFS);
if (substType->isEqual(origType))
return ProtocolConformanceRef(mutableThis);
auto *generic = cast<NormalProtocolConformance>(mutableThis);
auto subMap = SubstitutionMap::get(getGenericSignature(), IFS);
if (isVanishingTupleConformance(generic, subMap))
return unwrapVanishingTupleConformance(subMap);
auto &ctx = substType->getASTContext();
auto *concrete = ctx.getSpecializedConformance(substType, generic, subMap);
return ProtocolConformanceRef(concrete);
}
case ProtocolConformanceKind::Builtin: {
auto origType = getType();
if (!origType->hasTypeParameter() &&
!origType->hasArchetype())
return ProtocolConformanceRef(mutableThis);
auto substType = origType.subst(IFS);
// We do an exact pointer equality check because subst() can
// change sugar.
if (substType.getPointer() == origType.getPointer())
return ProtocolConformanceRef(mutableThis);
auto kind = cast<BuiltinProtocolConformance>(this)
->getBuiltinConformanceKind();
auto *concrete = substType->getASTContext()
.getBuiltinConformance(substType, getProtocol(), kind);
return ProtocolConformanceRef(concrete);
}
case ProtocolConformanceKind::Self:
return ProtocolConformanceRef(mutableThis);
case ProtocolConformanceKind::Inherited: {
// Substitute the base.
auto inheritedConformance
= cast<InheritedProtocolConformance>(this)->getInheritedConformance();
auto origType = getType();
if (!origType->hasTypeParameter() &&
!origType->hasArchetype()) {
return ProtocolConformanceRef(mutableThis);
}
auto origBaseType = inheritedConformance->getType();
if (origBaseType->hasTypeParameter() ||
origBaseType->hasArchetype()) {
// Substitute into the superclass.
auto substConformance = inheritedConformance->subst(IFS);