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737174fe9f016e35e72facbf44a90e3b3fd6af40
swift-mirror/lib/Sema/ConstraintSystem.cpp
Slava Pestov 737174fe9f AST: Add a DeclContext field to ComponentIdentTypeRepr 
Plumb this through and set it appropriately, but don't use it
for anything yet.
2017-07-18 22:10:33 -07:00

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//===--- ConstraintSystem.cpp - Constraint-based Type Checking ------------===//
//
// 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 the constraint-based type checker, anchored by the
// \c ConstraintSystem class, which provides type checking and type
// inference for expressions.
//
//===----------------------------------------------------------------------===//
#include "ConstraintSystem.h"
#include "ConstraintGraph.h"
#include "swift/AST/GenericEnvironment.h"
#include "swift/Basic/Statistic.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Format.h"
using namespace swift;
using namespace constraints;
#define DEBUG_TYPE "ConstraintSystem"
ExpressionTimer::~ExpressionTimer() {
auto elapsed = getElapsedProcessTimeInFractionalSeconds();
unsigned elapsedMS = static_cast<unsigned>(elapsed * 1000);
if (ShouldDump) {
// Round up to the nearest 100th of a millisecond.
llvm::errs() << llvm::format("%0.2f", ceil(elapsed * 100000) / 100)
<< "ms\t";
E->getLoc().print(llvm::errs(), Context.SourceMgr);
llvm::errs() << "\n";
}
if (WarnLimit != 0 && elapsedMS >= WarnLimit && E->getLoc().isValid())
Context.Diags.diagnose(E->getLoc(), diag::debug_long_expression,
elapsedMS, WarnLimit)
.highlight(E->getSourceRange());
}
ConstraintSystem::ConstraintSystem(TypeChecker &tc, DeclContext *dc,
ConstraintSystemOptions options)
: TC(tc), DC(dc), Options(options),
Arena(tc.Context, Allocator),
CG(*new ConstraintGraph(*this))
{
assert(DC && "context required");
}
ConstraintSystem::~ConstraintSystem() {
delete &CG;
}
void ConstraintSystem::incrementScopeCounter() {
SWIFT_FUNC_STAT;
CountScopes++;
// FIXME: (transitional) increment the redundant "always-on" counter.
if (TC.Context.Stats)
TC.Context.Stats->getFrontendCounters().NumConstraintScopes++;
}
bool ConstraintSystem::hasFreeTypeVariables() {
// Look for any free type variables.
for (auto tv : TypeVariables) {
if (!tv->getImpl().hasRepresentativeOrFixed()) {
return true;
}
}
return false;
}
void ConstraintSystem::addTypeVariable(TypeVariableType *typeVar) {
TypeVariables.push_back(typeVar);
// Notify the constraint graph.
(void)CG[typeVar];
}
void ConstraintSystem::mergeEquivalenceClasses(TypeVariableType *typeVar1,
TypeVariableType *typeVar2,
bool updateWorkList) {
assert(typeVar1 == getRepresentative(typeVar1) &&
"typeVar1 is not the representative");
assert(typeVar2 == getRepresentative(typeVar2) &&
"typeVar2 is not the representative");
assert(typeVar1 != typeVar2 && "cannot merge type with itself");
typeVar1->getImpl().mergeEquivalenceClasses(typeVar2, getSavedBindings());
// Merge nodes in the constraint graph.
CG.mergeNodes(typeVar1, typeVar2);
if (updateWorkList) {
addTypeVariableConstraintsToWorkList(typeVar1);
}
}
/// Determine whether the given type variables occurs in the given type.
bool ConstraintSystem::typeVarOccursInType(TypeVariableType *typeVar,
Type type,
bool *involvesOtherTypeVariables) {
SmallVector<TypeVariableType *, 4> typeVars;
type->getTypeVariables(typeVars);
bool result = false;
for (auto referencedTypeVar : typeVars) {
if (referencedTypeVar == typeVar) {
result = true;
if (!involvesOtherTypeVariables || *involvesOtherTypeVariables)
break;
continue;
}
if (involvesOtherTypeVariables)
*involvesOtherTypeVariables = true;
}
return result;
}
void ConstraintSystem::assignFixedType(TypeVariableType *typeVar, Type type,
bool updateState) {
assert(!type->hasError() &&
"Should not be assigning a type involving ErrorType!");
typeVar->getImpl().assignFixedType(type, getSavedBindings());
if (!updateState)
return;
if (!type->isTypeVariableOrMember()) {
// If this type variable represents a literal, check whether we picked the
// default literal type. First, find the corresponding protocol.
ProtocolDecl *literalProtocol = nullptr;
// If we have the constraint graph, we can check all type variables in
// the equivalence class. This is the More Correct path.
// FIXME: Eliminate the less-correct path.
auto typeVarRep = getRepresentative(typeVar);
for (auto tv : CG[typeVarRep].getEquivalenceClass()) {
auto locator = tv->getImpl().getLocator();
if (!locator || !locator->getPath().empty())
continue;
auto anchor = locator->getAnchor();
if (!anchor)
continue;
literalProtocol = TC.getLiteralProtocol(anchor);
if (literalProtocol)
break;
}
// If the protocol has a default type, check it.
if (literalProtocol) {
if (auto defaultType = TC.getDefaultType(literalProtocol, DC)) {
// Check whether the nominal types match. This makes sure that we
// properly handle Array vs. Array<T>.
if (defaultType->getAnyNominal() != type->getAnyNominal())
increaseScore(SK_NonDefaultLiteral);
}
}
}
// Notify the constraint graph.
CG.bindTypeVariable(typeVar, type);
addTypeVariableConstraintsToWorkList(typeVar);
}
void ConstraintSystem::setMustBeMaterializableRecursive(Type type)
{
assert(type->isMaterializable() &&
"argument to setMustBeMaterializableRecursive may not be inherently "
"non-materializable");
type = getFixedTypeRecursive(type, /*wantRValue=*/false);
type = type->lookThroughAllAnyOptionalTypes();
if (auto typeVar = type->getAs<TypeVariableType>()) {
typeVar->getImpl().setMustBeMaterializable(getSavedBindings());
} else if (auto *tupleTy = type->getAs<TupleType>()) {
for (auto elt : tupleTy->getElementTypes()) {
setMustBeMaterializableRecursive(elt);
}
}
}
void ConstraintSystem::addTypeVariableConstraintsToWorkList(
TypeVariableType *typeVar) {
// Gather the constraints affected by a change to this type variable.
SmallVector<Constraint *, 8> constraints;
CG.gatherConstraints(typeVar, constraints,
ConstraintGraph::GatheringKind::AllMentions);
// Add any constraints that aren't already active to the worklist.
for (auto constraint : constraints) {
if (!constraint->isActive()) {
ActiveConstraints.splice(ActiveConstraints.end(),
InactiveConstraints, constraint);
constraint->setActive(true);
}
}
}
/// Retrieve a dynamic result signature for the given declaration.
static std::tuple<char, ObjCSelector, CanType>
getDynamicResultSignature(ValueDecl *decl) {
if (auto func = dyn_cast<AbstractFunctionDecl>(decl)) {
// Handle functions.
auto type = func->getMethodInterfaceType();
return std::make_tuple(func->isStatic(), func->getObjCSelector(),
type->getCanonicalType());
}
if (auto asd = dyn_cast<AbstractStorageDecl>(decl)) {
// Handle properties and subscripts, anchored by the getter's selector.
return std::make_tuple(asd->isStatic(), asd->getObjCGetterSelector(),
asd->getInterfaceType()->getCanonicalType());
}
llvm_unreachable("Not a valid @objc member");
}
LookupResult &ConstraintSystem::lookupMember(Type base, DeclName name) {
// Check whether we've already performed this lookup.
auto knownMember = MemberLookups.find({base, name});
if (knownMember != MemberLookups.end())
return *knownMember->second;
// Lookup the member.
NameLookupOptions lookupOptions = defaultMemberLookupOptions;
if (isa<AbstractFunctionDecl>(DC))
lookupOptions |= NameLookupFlags::KnownPrivate;
MemberLookups[{base, name}] = None;
auto lookup = TC.lookupMember(DC, base, name, lookupOptions);
auto &result = MemberLookups[{base, name}];
result = std::move(lookup);
// If we aren't performing dynamic lookup, we're done.
if (!*result || !base->isAnyObject())
return *result;
// We are performing dynamic lookup. Filter out redundant results early.
llvm::DenseSet<std::tuple<char, ObjCSelector, CanType>> known;
result->filter([&](LookupResultEntry entry) -> bool {
auto *decl = entry.getValueDecl();
if (decl->isInvalid())
return false;
return known.insert(getDynamicResultSignature(decl)).second;
});
return *result;
}
ArrayRef<Type> ConstraintSystem::
getAlternativeLiteralTypes(KnownProtocolKind kind) {
unsigned index;
switch (kind) {
#define PROTOCOL_WITH_NAME(Id, Name) \
case KnownProtocolKind::Id: llvm_unreachable("Not a literal protocol");
#define EXPRESSIBLE_BY_LITERAL_PROTOCOL_WITH_NAME(Id, Name)
#include "swift/AST/KnownProtocols.def"
case KnownProtocolKind::ExpressibleByArrayLiteral: index = 0; break;
case KnownProtocolKind::ExpressibleByDictionaryLiteral:index = 1; break;
case KnownProtocolKind::ExpressibleByExtendedGraphemeClusterLiteral: index = 2;
break;
case KnownProtocolKind::ExpressibleByFloatLiteral: index = 3; break;
case KnownProtocolKind::ExpressibleByIntegerLiteral: index = 4; break;
case KnownProtocolKind::ExpressibleByStringInterpolation: index = 5; break;
case KnownProtocolKind::ExpressibleByStringLiteral: index = 6; break;
case KnownProtocolKind::ExpressibleByNilLiteral: index = 7; break;
case KnownProtocolKind::ExpressibleByBooleanLiteral: index = 8; break;
case KnownProtocolKind::ExpressibleByUnicodeScalarLiteral: index = 9; break;
case KnownProtocolKind::ExpressibleByColorLiteral: index = 10; break;
case KnownProtocolKind::ExpressibleByImageLiteral: index = 11; break;
case KnownProtocolKind::ExpressibleByFileReferenceLiteral: index = 12; break;
}
static_assert(NumAlternativeLiteralTypes == 13, "Wrong # of literal types");
// If we already looked for alternative literal types, return those results.
if (AlternativeLiteralTypes[index])
return *AlternativeLiteralTypes[index];
SmallVector<Type, 4> types;
// Some literal kinds are related.
switch (kind) {
#define PROTOCOL_WITH_NAME(Id, Name) \
case KnownProtocolKind::Id: llvm_unreachable("Not a literal protocol");
#define EXPRESSIBLE_BY_LITERAL_PROTOCOL_WITH_NAME(Id, Name)
#include "swift/AST/KnownProtocols.def"
case KnownProtocolKind::ExpressibleByArrayLiteral:
case KnownProtocolKind::ExpressibleByDictionaryLiteral:
break;
case KnownProtocolKind::ExpressibleByExtendedGraphemeClusterLiteral:
case KnownProtocolKind::ExpressibleByStringInterpolation:
case KnownProtocolKind::ExpressibleByStringLiteral:
case KnownProtocolKind::ExpressibleByUnicodeScalarLiteral:
break;
case KnownProtocolKind::ExpressibleByIntegerLiteral:
// Integer literals can be treated as floating point literals.
if (auto floatProto = TC.Context.getProtocol(
KnownProtocolKind::ExpressibleByFloatLiteral)) {
if (auto defaultType = TC.getDefaultType(floatProto, DC)) {
types.push_back(defaultType);
}
}
break;
case KnownProtocolKind::ExpressibleByFloatLiteral:
break;
case KnownProtocolKind::ExpressibleByNilLiteral:
case KnownProtocolKind::ExpressibleByBooleanLiteral:
break;
case KnownProtocolKind::ExpressibleByColorLiteral:
case KnownProtocolKind::ExpressibleByImageLiteral:
case KnownProtocolKind::ExpressibleByFileReferenceLiteral:
break;
}
AlternativeLiteralTypes[index] = allocateCopy(types);
return *AlternativeLiteralTypes[index];
}
ConstraintLocator *ConstraintSystem::getConstraintLocator(
Expr *anchor,
ArrayRef<ConstraintLocator::PathElement> path,
unsigned summaryFlags) {
assert(summaryFlags == ConstraintLocator::getSummaryFlagsForPath(path));
// Check whether a locator with this anchor + path already exists.
llvm::FoldingSetNodeID id;
ConstraintLocator::Profile(id, anchor, path);
void *insertPos = nullptr;
auto locator = ConstraintLocators.FindNodeOrInsertPos(id, insertPos);
if (locator)
return locator;
// Allocate a new locator and add it to the set.
locator = ConstraintLocator::create(getAllocator(), anchor, path,
summaryFlags);
ConstraintLocators.InsertNode(locator, insertPos);
return locator;
}
ConstraintLocator *ConstraintSystem::getConstraintLocator(
const ConstraintLocatorBuilder &builder) {
// If the builder has an empty path, just extract its base locator.
if (builder.hasEmptyPath()) {
return builder.getBaseLocator();
}
// We have to build a new locator. Extract the paths from the builder.
SmallVector<LocatorPathElt, 4> path;
Expr *anchor = builder.getLocatorParts(path);
return getConstraintLocator(anchor, path, builder.getSummaryFlags());
}
Type ConstraintSystem::openUnboundGenericType(UnboundGenericType *unbound,
ConstraintLocatorBuilder locator,
OpenedTypeMap &replacements) {
auto unboundDecl = unbound->getDecl();
if (unboundDecl->isInvalid())
return ErrorType::get(getASTContext());
// If the unbound decl hasn't been validated yet, we have a circular
// dependency that isn't being diagnosed properly.
if (!unboundDecl->getGenericSignature()) {
TC.diagnose(unboundDecl, diag::circular_reference);
return ErrorType::get(unbound);
}
auto parentTy = unbound->getParent();
if (parentTy) {
parentTy = openUnboundGenericType(parentTy, locator);
unbound = UnboundGenericType::get(unboundDecl, parentTy,
getASTContext());
}
// Open up the generic type.
openGeneric(unboundDecl->getInnermostDeclContext(),
unboundDecl->getDeclContext(),
unboundDecl->getGenericSignature(),
/*skipProtocolSelfConstraint=*/false,
locator,
replacements);
if (parentTy) {
auto subs = parentTy->getContextSubstitutions(
unboundDecl->getDeclContext());
for (auto pair : subs) {
auto found = replacements.find(
cast<GenericTypeParamType>(pair.first));
assert(found != replacements.end() &&
"Missing generic parameter?");
addConstraint(ConstraintKind::Equal, found->second, pair.second,
locator);
}
}
// Map the generic parameters to their corresponding type variables.
llvm::SmallVector<TypeLoc, 4> arguments;
for (auto gp : unboundDecl->getInnermostGenericParamTypes()) {
auto found = replacements.find(
cast<GenericTypeParamType>(gp->getCanonicalType()));
assert(found != replacements.end() &&
"Missing generic parameter?");
arguments.push_back(TypeLoc::withoutLoc(found->second));
}
// FIXME: For some reason we can end up with unbound->getDecl()
// pointing at a generic TypeAliasDecl here. If we find a way to
// handle generic TypeAliases elsewhere, this can just become a
// call to BoundGenericType::get().
return TC.applyUnboundGenericArguments(
unbound, unboundDecl,
SourceLoc(), DC, arguments,
/*options*/TypeResolutionOptions(),
/*resolver*/nullptr,
/*unsatisfiedDependency*/nullptr);
}
Type ConstraintSystem::openUnboundGenericType(
Type type,
ConstraintLocatorBuilder locator) {
assert(!type->hasTypeParameter());
if (!type->hasUnboundGenericType())
return type;
return type.transform([&](Type type) -> Type {
if (auto unbound = type->getAs<UnboundGenericType>()) {
OpenedTypeMap replacements;
return openUnboundGenericType(unbound, locator, replacements);
}
return type;
});
}
Type ConstraintSystem::openType(Type type, OpenedTypeMap &replacements) {
assert(!type->hasUnboundGenericType());
if (!type->hasTypeParameter())
return type;
return type.transform([&](Type type) -> Type {
assert(!type->is<GenericFunctionType>());
// Replace a generic type parameter with its corresponding type variable.
if (auto genericParam = type->getAs<GenericTypeParamType>()) {
auto known = replacements.find(
cast<GenericTypeParamType>(genericParam->getCanonicalType()));
assert(known != replacements.end());
return known->second;
}
return type;
});
}
/// Remove argument labels from the function type.
static Type removeArgumentLabels(Type type, unsigned numArgumentLabels) {
// If there is nothing to remove, don't.
if (numArgumentLabels == 0) return type;
auto fnType = type->getAs<FunctionType>();
// Drop argument labels from the input type.
Type inputType = fnType->getInput();
if (auto tupleTy = dyn_cast<TupleType>(inputType.getPointer())) {
SmallVector<TupleTypeElt, 4> elements;
elements.reserve(tupleTy->getNumElements());
for (const auto &elt : tupleTy->getElements()) {
elements.push_back(elt.getWithoutName());
}
inputType = TupleType::get(elements, type->getASTContext());
}
return FunctionType::get(inputType,
removeArgumentLabels(fnType->getResult(),
numArgumentLabels - 1),
fnType->getExtInfo());
}
Type ConstraintSystem::openFunctionType(
AnyFunctionType *funcType,
unsigned numArgumentLabelsToRemove,
ConstraintLocatorBuilder locator,
OpenedTypeMap &replacements,
DeclContext *innerDC,
DeclContext *outerDC,
bool skipProtocolSelfConstraint) {
Type type;
if (auto *genericFn = funcType->getAs<GenericFunctionType>()) {
// Open up the generic parameters and requirements.
openGeneric(innerDC,
outerDC,
genericFn->getGenericSignature(),
skipProtocolSelfConstraint,
locator,
replacements);
// Transform the input and output types.
auto inputTy = openType(genericFn->getInput(), replacements);
auto resultTy = openType(genericFn->getResult(), replacements);
// Build the resulting (non-generic) function type.
funcType = FunctionType::get(inputTy, resultTy,
FunctionType::ExtInfo().
withThrows(genericFn->throws()));
}
return removeArgumentLabels(funcType, numArgumentLabelsToRemove);
}
Optional<Type> ConstraintSystem::isArrayType(Type type) {
if (auto boundStruct = type->getAs<BoundGenericStructType>()) {
if (boundStruct->getDecl() == type->getASTContext().getArrayDecl())
return boundStruct->getGenericArgs()[0];
}
return None;
}
Optional<std::pair<Type, Type>> ConstraintSystem::isDictionaryType(Type type) {
if (auto boundStruct = type->getAs<BoundGenericStructType>()) {
if (boundStruct->getDecl() == type->getASTContext().getDictionaryDecl()) {
auto genericArgs = boundStruct->getGenericArgs();
return std::make_pair(genericArgs[0], genericArgs[1]);
}
}
return None;
}
Optional<Type> ConstraintSystem::isSetType(Type type) {
if (auto boundStruct = type->getAs<BoundGenericStructType>()) {
if (boundStruct->getDecl() == type->getASTContext().getSetDecl())
return boundStruct->getGenericArgs()[0];
}
return None;
}
bool ConstraintSystem::isAnyHashableType(Type type) {
if (auto tv = type->getAs<TypeVariableType>()) {
auto fixedType = getFixedType(tv);
return fixedType && isAnyHashableType(fixedType);
}
if (auto st = type->getAs<StructType>()) {
return st->getDecl() == TC.Context.getAnyHashableDecl();
}
return false;
}
Type ConstraintSystem::getFixedTypeRecursive(Type type,
TypeMatchOptions &flags,
bool wantRValue,
bool retainParens) {
if (wantRValue)
type = type->getRValueType();
if (retainParens) {
if (auto parenTy = dyn_cast<ParenType>(type.getPointer())) {
type = getFixedTypeRecursive(parenTy->getUnderlyingType(), flags,
wantRValue, retainParens);
return ParenType::get(getASTContext(), type);
}
}
while (true) {
if (auto depMemType = type->getAs<DependentMemberType>()) {
if (!depMemType->getBase()->isTypeVariableOrMember()) return type;
// FIXME: Perform a more limited simplification?
Type newType = simplifyType(type);
if (newType.getPointer() == type.getPointer()) return type;
if (wantRValue)
newType = newType->getRValueType();
type = newType;
// Once we've simplified a dependent member type, we need to generate a
// new constraint.
flags |= TMF_GenerateConstraints;
continue;
}
if (auto typeVar = type->getAs<TypeVariableType>()) {
if (auto fixed = getFixedType(typeVar)) {
if (wantRValue)
fixed = fixed->getRValueType();
type = fixed;
continue;
}
break;
}
break;
}
return type;
}
/// Does a var or subscript produce an l-value?
///
/// \param baseType - the type of the base on which this object
/// is being accessed; must be null if and only if this is not
/// a type member
static bool doesStorageProduceLValue(TypeChecker &TC,
AbstractStorageDecl *storage,
Type baseType, DeclContext *useDC,
const DeclRefExpr *base = nullptr) {
// Unsettable storage decls always produce rvalues.
if (!storage->isSettable(useDC, base))
return false;
if (TC.Context.LangOpts.EnableAccessControl &&
!storage->isSetterAccessibleFrom(useDC))
return false;
// If there is no base, or if the base isn't being used, it is settable.
// This is only possible for vars.
if (auto var = dyn_cast<VarDecl>(storage)) {
if (!baseType || var->isStatic())
return true;
}
// If the base is an lvalue, then a reference produces an lvalue.
if (baseType->is<LValueType>())
return true;
// Stored properties of reference types produce lvalues.
if (baseType->hasReferenceSemantics() && storage->hasStorage())
return true;
// So the base is an rvalue type. The only way an accessor can
// produce an lvalue is if we have a property where both the
// getter and setter are nonmutating.
return !storage->hasStorage() &&
!storage->isGetterMutating() &&
storage->isSetterNonMutating();
}
Type TypeChecker::getUnopenedTypeOfReference(VarDecl *value, Type baseType,
DeclContext *UseDC,
const DeclRefExpr *base,
bool wantInterfaceType) {
validateDecl(value);
if (value->isInvalid())
return ErrorType::get(Context);
Type requestedType = (wantInterfaceType
? value->getInterfaceType()
: value->getType());
requestedType = requestedType->getWithoutSpecifierType()
->getReferenceStorageReferent();
// If we're dealing with contextual types, and we referenced this type from
// a different context, map the type.
if (!wantInterfaceType && requestedType->hasArchetype()) {
auto valueDC = value->getDeclContext();
if (valueDC != UseDC) {
Type mapped = valueDC->mapTypeOutOfContext(requestedType);
requestedType = UseDC->mapTypeIntoContext(mapped);
}
}
// Qualify storage declarations with an lvalue when appropriate.
// Otherwise, they yield rvalues (and the access must be a load).
if (doesStorageProduceLValue(*this, value, baseType, UseDC, base)) {
return LValueType::get(requestedType);
}
return requestedType;
}
void ConstraintSystem::recordOpenedTypes(
ConstraintLocatorBuilder locator,
const OpenedTypeMap &replacements) {
if (replacements.empty())
return;
// If the last path element is an archetype or associated type, ignore it.
SmallVector<LocatorPathElt, 2> pathElts;
Expr *anchor = locator.getLocatorParts(pathElts);
if (!pathElts.empty() &&
(pathElts.back().getKind() == ConstraintLocator::Archetype ||
pathElts.back().getKind() == ConstraintLocator::AssociatedType))
return;
// If the locator is empty, ignore it.
if (!anchor && pathElts.empty())
return;
ConstraintLocator *locatorPtr = getConstraintLocator(locator);
assert(locatorPtr && "No locator for opened types?");
assert(std::find_if(OpenedTypes.begin(), OpenedTypes.end(),
[&](const std::pair<ConstraintLocator *,
ArrayRef<OpenedType>> &entry) {
return entry.first == locatorPtr;
}) == OpenedTypes.end() &&
"already registered opened types for this locator");
OpenedType* openedTypes
= Allocator.Allocate<OpenedType>(replacements.size());
std::copy(replacements.begin(), replacements.end(), openedTypes);
OpenedTypes.push_back({ locatorPtr,
llvm::makeArrayRef(openedTypes,
replacements.size()) });
}
/// Determine how many levels of argument labels should be removed from the
/// function type when referencing the given declaration.
static unsigned getNumRemovedArgumentLabels(TypeChecker &TC, ValueDecl *decl,
bool isCurriedInstanceReference,
FunctionRefKind functionRefKind) {
unsigned numParameterLists = 0;
// Enum element with associated value has to be treated
// as regular function value and all of the labels have to be
// stripped from its parameters.
//
// enum E {
// case foo(a: Int)
// }
// let bar: [Int] = []
// bar.map(E.foo)
//
// `E.foo` has to act as a regular function type passed as a value.
if (!TC.getLangOpts().isSwiftVersion3()) {
if (auto *EED = dyn_cast<EnumElementDecl>(decl)) {
numParameterLists = EED->hasAssociatedValues() ? 2 : 1;
}
}
// Only applicable to functions. Nothing else should have argument labels in
// the type.
if (auto func = dyn_cast<AbstractFunctionDecl>(decl))
numParameterLists = func->getNumParameterLists();
if (numParameterLists == 0)
return 0;
switch (functionRefKind) {
case FunctionRefKind::Unapplied:
case FunctionRefKind::Compound:
// Always remove argument labels from unapplied references and references
// that use a compound name.
return numParameterLists;
case FunctionRefKind::SingleApply:
// If we have fewer than two parameter lists, leave the labels.
if (numParameterLists < 2)
return 0;
// If this is a curried reference to an instance method, where 'self' is
// being applied, e.g., "ClassName.instanceMethod(self)", remove the
// argument labels from the resulting function type. The 'self' parameter is
// always unlabeled, so this operation is a no-op for the actual application.
return isCurriedInstanceReference ? numParameterLists : 1;
case FunctionRefKind::DoubleApply:
// Never remove argument labels from a double application.
return 0;
}
llvm_unreachable("Unhandled FunctionRefKind in switch.");
}
std::pair<Type, Type>
ConstraintSystem::getTypeOfReference(ValueDecl *value,
FunctionRefKind functionRefKind,
ConstraintLocatorBuilder locator,
const DeclRefExpr *base) {
if (value->getDeclContext()->isTypeContext() && isa<FuncDecl>(value)) {
// Unqualified lookup can find operator names within nominal types.
auto func = cast<FuncDecl>(value);
assert(func->isOperator() && "Lookup should only find operators");
OpenedTypeMap replacements;
auto openedType = openFunctionType(
func->getInterfaceType()->castTo<AnyFunctionType>(),
/*numArgumentLabelsToRemove=*/0,
locator, replacements,
func->getInnermostDeclContext(),
func->getDeclContext(),
/*skipProtocolSelfConstraint=*/false);
auto openedFnType = openedType->castTo<FunctionType>();
// If we opened up any type variables, record the replacements.
recordOpenedTypes(locator, replacements);
// If this is a method whose result type is dynamic Self, replace
// DynamicSelf with the actual object type.
if (!func->getDeclContext()->getAsProtocolOrProtocolExtensionContext()) {
if (func->hasDynamicSelf()) {
Type selfTy = openedFnType->getInput()->getRValueInstanceType();
openedType = openedType->replaceCovariantResultType(
selfTy,
func->getNumParameterLists());
openedFnType = openedType->castTo<FunctionType>();
}
} else {
openedType = openedType->eraseDynamicSelfType();
openedFnType = openedType->castTo<FunctionType>();
}
// The reference implicitly binds 'self'.
return { openedType, openedFnType->getResult() };
}
// Unqualified reference to a local or global function.
if (auto funcDecl = dyn_cast<AbstractFunctionDecl>(value)) {
OpenedTypeMap replacements;
auto funcType = funcDecl->getInterfaceType()->castTo<AnyFunctionType>();
auto openedType =
openFunctionType(
funcType,
getNumRemovedArgumentLabels(TC, funcDecl,
/*isCurriedInstanceReference=*/false,
functionRefKind),
locator, replacements,
funcDecl->getInnermostDeclContext(),
funcDecl->getDeclContext(),
/*skipProtocolSelfConstraint=*/false);
// If we opened up any type variables, record the replacements.
recordOpenedTypes(locator, replacements);
return { openedType, openedType };
}
// Unqualified reference to a type.
if (auto typeDecl = dyn_cast<TypeDecl>(value)) {
// Resolve the reference to this type declaration in our current context.
auto type = TC.resolveTypeInContext(typeDecl, nullptr, DC,
TR_InExpression,
/*isSpecialized=*/false);
// Open the type.
type = openUnboundGenericType(type, locator);
// Module types are not wrapped in metatypes.
if (type->is<ModuleType>())
return { type, type };
// If it's a value reference, refer to the metatype.
type = MetatypeType::get(type);
return { type, type };
}
// Only remaining case: unqualified reference to a property.
auto *varDecl = cast<VarDecl>(value);
// Determine the type of the value, opening up that type if necessary.
bool wantInterfaceType = !varDecl->getDeclContext()->isLocalContext();
Type valueType = TC.getUnopenedTypeOfReference(varDecl, Type(), DC, base,
wantInterfaceType);
assert(!valueType->hasUnboundGenericType() &&
!valueType->hasTypeParameter());
// If this is a let-param whose type is a type variable, this is an untyped
// closure param that may be bound to an inout type later. References to the
// param should have lvalue type instead. Express the relationship with a new
// constraint.
if (auto *param = dyn_cast<ParamDecl>(varDecl)) {
if (param->isLet() && valueType->is<TypeVariableType>()) {
Type paramType = valueType;
valueType = createTypeVariable(getConstraintLocator(locator),
TVO_CanBindToLValue |
TVO_CanBindToInOut);
addConstraint(ConstraintKind::BindParam, paramType, valueType,
getConstraintLocator(locator));
}
}
return { valueType, valueType };
}
/// Bind type variables for archetypes that are determined from
/// context.
///
/// For example, if we are opening a generic function type
/// nested inside another function, we must bind the outer
/// generic parameters to context archetypes, because the
/// nested function can "capture" these outer generic parameters.
///
/// Another case where this comes up is if a generic type is
/// nested inside a function. We don't support codegen for this
/// yet, but again we need to bind any outer generic parameters
/// to context archetypes, because they're not free.
///
/// A final case we have to handle, even though it is invalid, is
/// when a type is nested inside another protocol. We bind the
/// protocol type variable for the protocol Self to its archetype
/// in protocol context. This of course makes no sense, but we
/// can't leave the type variable dangling, because then we crash
/// later.
///
/// If we ever do want to allow nominal types to be nested inside
/// protocols, the key is to set their declared type to a
/// NominalType whose parent is the 'Self' generic parameter, and
/// not the ProtocolType. Then, within a conforming type context,
/// we can 'reparent' the NominalType to that concrete type, and
/// resolve references to associated types inside that NominalType
/// relative to this concrete 'Self' type.
///
/// Also, of course IRGen would have to know to store the 'Self'
/// metadata as an extra hidden generic parameter in the metadata
/// of such a type, etc.
static void bindArchetypesFromContext(
ConstraintSystem &cs,
DeclContext *outerDC,
ConstraintLocator *locatorPtr,
const OpenedTypeMap &replacements) {
auto *genericEnv = cs.DC->getGenericEnvironmentOfContext();
for (const auto *parentDC = outerDC;
!parentDC->isModuleScopeContext();
parentDC = parentDC->getParent()) {
if (parentDC->isTypeContext() &&
(parentDC == outerDC ||
!parentDC->getAsProtocolOrProtocolExtensionContext()))
continue;
auto *genericSig = parentDC->getGenericSignatureOfContext();
if (!genericSig)
break;
for (auto *paramTy : genericSig->getGenericParams()) {
auto found = replacements.find(cast<GenericTypeParamType>(
paramTy->getCanonicalType()));
// We might not have a type variable for this generic parameter
// because either we're opening up an UnboundGenericType,
// in which case we only want to infer the innermost generic
// parameters, or because this generic parameter was constrained
// away into a concrete type.
if (found != replacements.end()) {
auto typeVar = found->second;
auto contextTy = genericEnv->mapTypeIntoContext(paramTy);
cs.addConstraint(ConstraintKind::Bind, typeVar, contextTy,
locatorPtr);
}
}
break;
}
}
void ConstraintSystem::openGeneric(
DeclContext *innerDC,
DeclContext *outerDC,
GenericSignature *sig,
bool skipProtocolSelfConstraint,
ConstraintLocatorBuilder locator,
OpenedTypeMap &replacements) {
if (sig == nullptr)
return;
auto locatorPtr = getConstraintLocator(locator);
auto *genericEnv = innerDC->getGenericEnvironmentOfContext();
// Create the type variables for the generic parameters.
for (auto gp : sig->getGenericParams()) {
auto contextTy = genericEnv->mapTypeIntoContext(gp);
if (auto *archetype = contextTy->getAs<ArchetypeType>())
locatorPtr = getConstraintLocator(
locator.withPathElement(LocatorPathElt(archetype)));
auto typeVar = createTypeVariable(locatorPtr,
TVO_PrefersSubtypeBinding);
auto result = replacements.insert(
std::make_pair(cast<GenericTypeParamType>(gp->getCanonicalType()),
typeVar));
assert(result.second);
(void) result;
}
// Remember that any new constraints generated by opening this generic are
// due to the opening.
locatorPtr = getConstraintLocator(
locator.withPathElement(ConstraintLocator::OpenedGeneric));
bindArchetypesFromContext(*this, outerDC, locatorPtr, replacements);
// Add the requirements as constraints.
for (auto req : sig->getRequirements()) {
switch (req.getKind()) {
case RequirementKind::Conformance: {
auto subjectTy = openType(req.getFirstType(), replacements);
auto proto = req.getSecondType()->castTo<ProtocolType>();
auto protoDecl = proto->getDecl();
// Determine whether this is the protocol 'Self' constraint we should
// skip.
if (skipProtocolSelfConstraint &&
protoDecl == outerDC &&
protoDecl->getSelfInterfaceType()->isEqual(req.getFirstType()))
break;
addConstraint(ConstraintKind::ConformsTo, subjectTy, proto,
locatorPtr);
break;
}
case RequirementKind::Layout: {
auto subjectTy = openType(req.getFirstType(), replacements);
auto layoutConstraint = req.getLayoutConstraint();
if (layoutConstraint->isClass())
addConstraint(ConstraintKind::ConformsTo, subjectTy,
TC.Context.getAnyObjectType(),
locatorPtr);
// Nothing else can appear outside of @_specialize yet, and Sema
// doesn't know how to check.
break;
}
case RequirementKind::Superclass: {
auto subjectTy = openType(req.getFirstType(), replacements);
auto boundTy = openType(req.getSecondType(), replacements);
addConstraint(ConstraintKind::Subtype, subjectTy, boundTy, locatorPtr);
break;
}
case RequirementKind::SameType: {
auto firstTy = openType(req.getFirstType(), replacements);
auto secondTy = openType(req.getSecondType(), replacements);
addConstraint(ConstraintKind::Bind, firstTy, secondTy, locatorPtr);
break;
}
}
}
}
/// Add the constraint on the type used for the 'Self' type for a member
/// reference.
///
/// \param cs The constraint system.
///
/// \param objectTy The type of the object that we're using to access the
/// member.
///
/// \param selfTy The instance type of the context in which the member is
/// declared.
static void addSelfConstraint(ConstraintSystem &cs, Type objectTy, Type selfTy,
ConstraintLocatorBuilder locator){
assert(!selfTy->is<ProtocolType>());
// Otherwise, use a subtype constraint for classes to cope with inheritance.
if (selfTy->getClassOrBoundGenericClass()) {
cs.addConstraint(ConstraintKind::Subtype, objectTy, selfTy,
cs.getConstraintLocator(locator));
return;
}
// Otherwise, the types must be equivalent.
cs.addConstraint(ConstraintKind::Equal, objectTy, selfTy,
cs.getConstraintLocator(locator));
}
/// Determine whether the given locator is for a witness or requirement.
static bool isRequirementOrWitness(const ConstraintLocatorBuilder &locator) {
if (auto last = locator.last()) {
return last->getKind() == ConstraintLocator::Requirement ||
last->getKind() == ConstraintLocator::Witness;
}
return false;
}
std::pair<Type, Type>
ConstraintSystem::getTypeOfMemberReference(
Type baseTy, ValueDecl *value, DeclContext *useDC,
bool isDynamicResult,
FunctionRefKind functionRefKind,
ConstraintLocatorBuilder locator,
const DeclRefExpr *base,
OpenedTypeMap *replacementsPtr) {
// Figure out the instance type used for the base.
Type baseObjTy = getFixedTypeRecursive(baseTy, /*wantRValue=*/true);
bool isInstance = true;
if (auto baseMeta = baseObjTy->getAs<AnyMetatypeType>()) {
baseObjTy = baseMeta->getInstanceType();
isInstance = false;
}
// If the base is a module type, just use the type of the decl.
if (baseObjTy->is<ModuleType>()) {
return getTypeOfReference(value, functionRefKind, locator, base);
}
// Don't open existentials when accessing typealias members of
// protocols.
if (auto *alias = dyn_cast<TypeAliasDecl>(value)) {
if (baseObjTy->isExistentialType()) {
auto memberTy = alias->getDeclaredInterfaceType();
// If we end up with a protocol typealias here, it's underlying
// type must be fully concrete.
assert(!memberTy->hasTypeParameter());
auto openedType = FunctionType::get(baseObjTy, memberTy);
return { openedType, memberTy };
}
}
if (auto *typeDecl = dyn_cast<TypeDecl>(value)) {
assert(!isa<ModuleDecl>(typeDecl) && "Nested module?");
auto memberTy = TC.substMemberTypeWithBase(DC->getParentModule(),
typeDecl, baseObjTy);
// Open the type if it was a reference to a generic type.
memberTy = openUnboundGenericType(memberTy, locator);
// Wrap it in a metatype.
memberTy = MetatypeType::get(memberTy);
auto openedType = FunctionType::get(baseObjTy, memberTy);
return { openedType, memberTy };
}
// Figure out the declaration context to use when opening this type.
DeclContext *innerDC = value->getInnermostDeclContext();
DeclContext *outerDC = value->getDeclContext();
// Open the type of the generic function or member of a generic type.
Type openedType;
OpenedTypeMap localReplacements;
auto &replacements = replacementsPtr ? *replacementsPtr : localReplacements;
bool isCurriedInstanceReference = value->isInstanceMember() && !isInstance;
unsigned numRemovedArgumentLabels =
getNumRemovedArgumentLabels(TC, value, isCurriedInstanceReference,
functionRefKind);
AnyFunctionType *funcType;
if (isa<AbstractFunctionDecl>(value) ||
isa<EnumElementDecl>(value)) {
// This is the easy case.
funcType = value->getInterfaceType()->castTo<AnyFunctionType>();
} else {
// For a property, build a type (Self) -> PropType.
// For a subscript, build a type (Self) -> (Indices...) -> ElementType.
//
// If the access is mutating, wrap the storage type in an lvalue type.
Type refType;
if (auto *subscript = dyn_cast<SubscriptDecl>(value)) {
auto elementTy = subscript->getElementInterfaceType();
if (doesStorageProduceLValue(TC, subscript, baseTy, useDC, base))
elementTy = LValueType::get(elementTy);
// See ConstraintSystem::resolveOverload() -- optional and dynamic
// subscripts are a special case, because the optionality is
// applied to the result type and not the type of the reference.
if (!isRequirementOrWitness(locator)) {
if (subscript->getAttrs().hasAttribute<OptionalAttr>())
elementTy = OptionalType::get(elementTy->getRValueType());
else if (isDynamicResult) {
elementTy = ImplicitlyUnwrappedOptionalType::get(
elementTy->getRValueType());
}
}
auto indicesTy = subscript->getIndicesInterfaceType();
refType = FunctionType::get(indicesTy, elementTy,
AnyFunctionType::ExtInfo());
} else {
refType = TC.getUnopenedTypeOfReference(cast<VarDecl>(value),
baseTy, useDC, base,
/*wantInterfaceType=*/true);
}
auto selfTy = outerDC->getSelfInterfaceType();
// If self is a value type and the base type is an lvalue, wrap it in an
// inout type.
if (!outerDC->getDeclaredTypeOfContext()->hasReferenceSemantics() &&
baseTy->is<LValueType>() &&
!selfTy->hasError())
selfTy = InOutType::get(selfTy);
// If the storage is generic, add a generic signature.
if (auto *sig = innerDC->getGenericSignatureOfContext()) {
funcType = GenericFunctionType::get(sig, selfTy, refType,
AnyFunctionType::ExtInfo());
} else {
funcType = FunctionType::get(selfTy, refType,
AnyFunctionType::ExtInfo());
}
}
openedType = openFunctionType(funcType, numRemovedArgumentLabels,
locator, replacements, innerDC, outerDC,
/*skipProtocolSelfConstraint=*/true);
if (!outerDC->getAsProtocolOrProtocolExtensionContext()) {
// Class methods returning Self as well as constructors get the
// result replaced with the base object type.
if (auto func = dyn_cast<AbstractFunctionDecl>(value)) {
if ((isa<FuncDecl>(func) &&
cast<FuncDecl>(func)->hasDynamicSelf()) ||
(isa<ConstructorDecl>(func) &&
!baseObjTy->getAnyOptionalObjectType())) {
openedType = openedType->replaceCovariantResultType(
baseObjTy,
func->getNumParameterLists());
}
}
} else {
// Protocol requirements returning Self have a dynamic Self return
// type. Erase the dynamic Self since it only comes into play during
// protocol conformance checking.
openedType = openedType->eraseDynamicSelfType();
}
// If we are looking at a member of an existential, open the existential.
Type baseOpenedTy = baseObjTy;
if (baseObjTy->isExistentialType()) {
ArchetypeType *openedArchetype = ArchetypeType::getOpened(baseObjTy);
OpenedExistentialTypes.push_back({ getConstraintLocator(locator),
openedArchetype });
baseOpenedTy = openedArchetype;
}
// Constrain the 'self' object type.
auto openedFnType = openedType->castTo<FunctionType>();
Type selfObjTy = openedFnType->getInput()->getRValueInstanceType();
if (outerDC->getAsProtocolOrProtocolExtensionContext()) {
// For a protocol, substitute the base object directly. We don't need a
// conformance constraint because we wouldn't have found the declaration
// if it didn't conform.
addConstraint(ConstraintKind::Equal, baseOpenedTy, selfObjTy,
getConstraintLocator(locator));
} else if (!isDynamicResult) {
addSelfConstraint(*this, baseOpenedTy, selfObjTy, locator);
}
// Compute the type of the reference.
Type type;
if (!value->isInstanceMember() || isInstance) {
// For a static member referenced through a metatype or an instance
// member referenced through an instance, strip off the 'self'.
type = openedFnType->getResult();
} else if (isDynamicResult && isa<AbstractFunctionDecl>(value)) {
// For a dynamic result referring to an instance function through
// an object of metatype type, replace the 'Self' parameter with
// a AnyObject member.
auto anyObjectTy = TC.Context.getAnyObjectType();
type = openedFnType->replaceSelfParameterType(anyObjectTy);
} else {
// For an unbound instance method reference, replace the 'Self'
// parameter with the base type.
type = openedFnType->replaceSelfParameterType(baseObjTy);
}
// When accessing protocol members with an existential base, replace
// the 'Self' type parameter with the existential type, since formally
// the access will operate on existentials and not type parameters.
if (!isDynamicResult &&
baseObjTy->isExistentialType() &&
outerDC->getAsProtocolOrProtocolExtensionContext()) {
auto selfTy = replacements[
cast<GenericTypeParamType>(outerDC->getSelfInterfaceType()
->getCanonicalType())];
type = type.transform([&](Type t) -> Type {
if (auto *selfTy = t->getAs<DynamicSelfType>())
t = selfTy->getSelfType();
if (t->is<TypeVariableType>())
if (t->isEqual(selfTy))
return baseObjTy;
if (auto *metatypeTy = t->getAs<MetatypeType>())
if (metatypeTy->getInstanceType()->isEqual(selfTy))
return ExistentialMetatypeType::get(baseObjTy);
return t;
});
}
// If we opened up any type variables, record the replacements.
recordOpenedTypes(locator, replacements);
return { openedType, type };
}
void ConstraintSystem::addOverloadSet(Type boundType,
ArrayRef<OverloadChoice> choices,
DeclContext *useDC,
ConstraintLocator *locator,
OverloadChoice *favoredChoice) {
assert(!choices.empty() && "Empty overload set");
// If there is a single choice, add the bind overload directly.
if (choices.size() == 1) {
addBindOverloadConstraint(boundType, choices.front(), locator, useDC);
return;
}
SmallVector<Constraint *, 4> overloads;
// As we do for other favored constraints, if a favored overload has been
// specified, let it be the first term in the disjunction.
if (favoredChoice) {
auto bindOverloadConstraint =
Constraint::createBindOverload(*this,
boundType,
*favoredChoice,
useDC,
locator);
assert((!favoredChoice->isDecl() ||
!favoredChoice->getDecl()->getAttrs().isUnavailable(
getASTContext())) &&
"Cannot make unavailable decl favored!");
bindOverloadConstraint->setFavored();
overloads.push_back(bindOverloadConstraint);
}
for (auto choice : choices) {
if (favoredChoice && (favoredChoice == &choice))
continue;
overloads.push_back(Constraint::createBindOverload(*this, boundType, choice,
useDC, locator));
}
addDisjunctionConstraint(overloads, locator, ForgetChoice, favoredChoice);
}
/// If we're resolving an overload set with a decl that has special type
/// checking semantics, set up the special-case type system and return true;
/// otherwise return false.
static bool
resolveOverloadForDeclWithSpecialTypeCheckingSemantics(ConstraintSystem &CS,
ConstraintLocator *locator,
Type boundType,
OverloadChoice choice,
Type &refType,
Type &openedFullType) {
assert(choice.getKind() == OverloadChoiceKind::Decl);
switch (CS.TC.getDeclTypeCheckingSemantics(choice.getDecl())) {
case DeclTypeCheckingSemantics::Normal:
return false;
case DeclTypeCheckingSemantics::TypeOf: {
// Proceed with a "DynamicType" operation. This produces an existential
// metatype from existentials, or a concrete metatype from non-
// existentials (as seen from the current abstraction level), which can't
// be expressed in the type system currently.
auto input = CS.createTypeVariable(
CS.getConstraintLocator(locator, ConstraintLocator::FunctionArgument),
TVO_CanBindToInOut);
auto output = CS.createTypeVariable(
CS.getConstraintLocator(locator, ConstraintLocator::FunctionResult),
TVO_CanBindToInOut);
auto inputArg = TupleTypeElt(input, CS.getASTContext().getIdentifier("of"));
auto inputTuple = TupleType::get(inputArg, CS.getASTContext());
CS.addConstraint(ConstraintKind::DynamicTypeOf, output, input,
CS.getConstraintLocator(locator, ConstraintLocator::RvalueAdjustment));
refType = FunctionType::get(inputTuple, output);
openedFullType = refType;
return true;
}
case DeclTypeCheckingSemantics::WithoutActuallyEscaping: {
// Proceed with a "WithoutActuallyEscaping" operation. The body closure
// receives a copy of the argument closure that is temporarily made
// @escaping.
auto noescapeClosure = CS.createTypeVariable(
CS.getConstraintLocator(locator, ConstraintLocator::FunctionArgument),
TVO_CanBindToInOut);
auto escapeClosure = CS.createTypeVariable(
CS.getConstraintLocator(locator, ConstraintLocator::FunctionArgument),
TVO_CanBindToInOut);
CS.addConstraint(ConstraintKind::EscapableFunctionOf,
escapeClosure, noescapeClosure,
CS.getConstraintLocator(locator, ConstraintLocator::RvalueAdjustment));
auto result = CS.createTypeVariable(
CS.getConstraintLocator(locator, ConstraintLocator::FunctionResult),
TVO_CanBindToInOut);
auto bodyClosure = FunctionType::get(
ParenType::get(CS.getASTContext(), escapeClosure), result,
FunctionType::ExtInfo(FunctionType::Representation::Swift,
/*autoclosure*/ false,
/*noescape*/ true,
/*throws*/ true));
TupleTypeElt argTupleElts[] = {
TupleTypeElt(noescapeClosure),
TupleTypeElt(bodyClosure, CS.getASTContext().getIdentifier("do")),
};
auto argTuple = TupleType::get(argTupleElts, CS.getASTContext());
refType = FunctionType::get(argTuple, result,
FunctionType::ExtInfo(FunctionType::Representation::Swift,
/*autoclosure*/ false,
/*noescape*/ false,
/*throws*/ true));
openedFullType = refType;
return true;
}
case DeclTypeCheckingSemantics::OpenExistential: {
// The body closure receives a freshly-opened archetype constrained by the
// existential type as its input.
auto openedTy = CS.createTypeVariable(
CS.getConstraintLocator(locator, ConstraintLocator::FunctionArgument),
TVO_CanBindToInOut);
auto existentialTy = CS.createTypeVariable(
CS.getConstraintLocator(locator, ConstraintLocator::FunctionArgument),
TVO_CanBindToInOut);
CS.addConstraint(ConstraintKind::OpenedExistentialOf,
openedTy, existentialTy,
CS.getConstraintLocator(locator, ConstraintLocator::RvalueAdjustment));
auto result = CS.createTypeVariable(
CS.getConstraintLocator(locator, ConstraintLocator::FunctionResult),
TVO_CanBindToInOut);
auto bodyClosure = FunctionType::get(
ParenType::get(CS.getASTContext(), openedTy), result,
FunctionType::ExtInfo(FunctionType::Representation::Swift,
/*autoclosure*/ false,
/*noescape*/ true,
/*throws*/ true));
TupleTypeElt argTupleElts[] = {
TupleTypeElt(existentialTy),
TupleTypeElt(bodyClosure, CS.getASTContext().getIdentifier("do")),
};
auto argTuple = TupleType::get(argTupleElts, CS.getASTContext());
refType = FunctionType::get(argTuple, result,
FunctionType::ExtInfo(FunctionType::Representation::Swift,
/*autoclosure*/ false,
/*noescape*/ false,
/*throws*/ true));
openedFullType = refType;
return true;
}
}
llvm_unreachable("Unhandled DeclTypeCheckingSemantics in switch.");
}
void ConstraintSystem::resolveOverload(ConstraintLocator *locator,
Type boundType,
OverloadChoice choice,
DeclContext *useDC) {
// Determine the type to which we'll bind the overload set's type.
Type refType;
Type openedFullType;
switch (auto kind = choice.getKind()) {
case OverloadChoiceKind::Decl:
// If we refer to a top-level decl with special type-checking semantics,
// handle it now.
if (resolveOverloadForDeclWithSpecialTypeCheckingSemantics(
*this, locator, boundType, choice, refType, openedFullType))
break;
LLVM_FALLTHROUGH;
case OverloadChoiceKind::DeclViaBridge:
case OverloadChoiceKind::DeclViaDynamic:
case OverloadChoiceKind::DeclViaUnwrappedOptional: {
bool isDynamicResult
= choice.getKind() == OverloadChoiceKind::DeclViaDynamic;
// Retrieve the type of a reference to the specific declaration choice.
if (auto baseTy = choice.getBaseType()) {
assert(!baseTy->hasTypeParameter());
auto getDotBase = [](const Expr *E) -> const DeclRefExpr * {
if (E == nullptr) return nullptr;
switch (E->getKind()) {
case ExprKind::MemberRef: {
auto Base = cast<MemberRefExpr>(E)->getBase();
return dyn_cast<const DeclRefExpr>(Base);
}
case ExprKind::UnresolvedDot: {
auto Base = cast<UnresolvedDotExpr>(E)->getBase();
return dyn_cast<const DeclRefExpr>(Base);
}
default:
return nullptr;
}
};
auto anchor = locator ? locator->getAnchor() : nullptr;
auto base = getDotBase(anchor);
std::tie(openedFullType, refType)
= getTypeOfMemberReference(baseTy, choice.getDecl(), useDC,
isDynamicResult,
choice.getFunctionRefKind(),
locator, base, nullptr);
} else {
std::tie(openedFullType, refType)
= getTypeOfReference(choice.getDecl(),
choice.getFunctionRefKind(), locator);
}
if (!isRequirementOrWitness(locator) &&
choice.getDecl()->getAttrs().hasAttribute<OptionalAttr>() &&
!isa<SubscriptDecl>(choice.getDecl())) {
// For a non-subscript declaration that is an optional
// requirement in a protocol, strip off the lvalue-ness (FIXME:
// one cannot assign to such declarations for now) and make a
// reference to that declaration be optional.
//
// Subscript declarations are handled within
// getTypeOfMemberReference(); their result types are optional.
refType = OptionalType::get(refType->getRValueType());
}
// For a non-subscript declaration found via dynamic lookup, strip
// off the lvalue-ness (FIXME: as a temporary hack. We eventually
// want this to work) and make a reference to that declaration be
// an implicitly unwrapped optional.
//
// Subscript declarations are handled within
// getTypeOfMemberReference(); their result types are unchecked
// optional.
else if (isDynamicResult && !isa<SubscriptDecl>(choice.getDecl())) {
refType = ImplicitlyUnwrappedOptionalType::get(refType->getRValueType());
}
// If the declaration is unavailable, note that in the score.
if (choice.getDecl()->getAttrs().isUnavailable(getASTContext())) {
increaseScore(SK_Unavailable);
}
break;
}
case OverloadChoiceKind::BaseType:
refType = choice.getBaseType();
break;
case OverloadChoiceKind::TupleIndex:
if (auto lvalueTy = choice.getBaseType()->getAs<LValueType>()) {
// When the base of a tuple lvalue, the member is always an lvalue.
auto tuple = lvalueTy->getObjectType()->castTo<TupleType>();
refType = tuple->getElementType(choice.getTupleIndex())->getRValueType();
refType = LValueType::get(refType);
} else {
// When the base is a tuple rvalue, the member is always an rvalue.
auto tuple = choice.getBaseType()->castTo<TupleType>();
refType = tuple->getElementType(choice.getTupleIndex())->getRValueType();
}
break;
case OverloadChoiceKind::KeyPathApplication: {
// Key path application looks like a subscript(keyPath: KeyPath<Base, T>).
// The element type is T or @lvalue T based on the key path subtype and
// the mutability of the base.
auto keyPathIndexTy = createTypeVariable(
getConstraintLocator(locator, ConstraintLocator::FunctionArgument),
TVO_CanBindToInOut);
auto elementTy = createTypeVariable(
getConstraintLocator(locator, ConstraintLocator::FunctionArgument),
TVO_CanBindToLValue |
TVO_CanBindToInOut);
auto elementObjTy = createTypeVariable(
getConstraintLocator(locator, ConstraintLocator::FunctionArgument),
TVO_CanBindToInOut);
addConstraint(ConstraintKind::Equal, elementTy, elementObjTy, locator);
// The element result is an lvalue or rvalue based on the key path class.
addKeyPathApplicationConstraint(
keyPathIndexTy, choice.getBaseType(), elementTy, locator);
TupleTypeElt indexTupleElts[] = {
TupleTypeElt(keyPathIndexTy, getASTContext().Id_keyPath),
};
auto indexTuple = TupleType::get(indexTupleElts, getASTContext());
auto subscriptTy = FunctionType::get(indexTuple, elementTy);
auto fullTy = FunctionType::get(choice.getBaseType(), subscriptTy);
openedFullType = fullTy;
refType = subscriptTy;
// Increase the score so that actual subscripts get preference.
increaseScore(SK_KeyPathSubscript);
}
}
assert(!refType->hasTypeParameter() && "Cannot have a dependent type here");
// If we're binding to an init member, the 'throws' need to line up between
// the bound and reference types.
if (choice.isDecl()) {
auto decl = choice.getDecl();
if (auto CD = dyn_cast<ConstructorDecl>(decl)) {
auto boundFunctionType = boundType->getAs<AnyFunctionType>();
if (boundFunctionType &&
CD->hasThrows() != boundFunctionType->throws()) {
boundType = FunctionType::get(boundFunctionType->getInput(),
boundFunctionType->getResult(),
boundFunctionType->getExtInfo().
withThrows());
}
}
}
// Add the type binding constraint.
addConstraint(ConstraintKind::Bind, boundType, refType, locator);
// Note that we have resolved this overload.
resolvedOverloadSets
= new (*this) ResolvedOverloadSetListItem{resolvedOverloadSets,
boundType,
choice,
locator,
openedFullType,
refType};
if (TC.getLangOpts().DebugConstraintSolver) {
auto &log = getASTContext().TypeCheckerDebug->getStream();
log.indent(solverState ? solverState->depth * 2 : 2)
<< "(overload set choice binding "
<< boundType->getString() << " := "
<< refType->getString() << ")\n";
}
}
/// Given that we're accessing a member of an ImplicitlyUnwrappedOptional<T>, is
/// the DC one of the special cases where we should not instead look at T?
static bool isPrivilegedAccessToImplicitlyUnwrappedOptional(DeclContext *DC,
NominalTypeDecl *D) {
assert(D == DC->getASTContext().getImplicitlyUnwrappedOptionalDecl());
// Walk up through the chain of current contexts.
for (; ; DC = DC->getParent()) {
assert(DC && "ran out of contexts before finding a module scope?");
// Look through local contexts.
if (DC->isLocalContext()) {
continue;
// If we're in a type context that's defining or extending
// ImplicitlyUnwrappedOptional<T>, we're privileged.
} else if (DC->isTypeContext()) {
if (DC->getAsNominalTypeOrNominalTypeExtensionContext() == D)
return true;
// Otherwise, we're privileged if we're within the same file that
// defines ImplicitlyUnwrappedOptional<T>.
} else {
assert(DC->isModuleScopeContext());
return (DC == D->getModuleScopeContext());
}
}
}
Type ConstraintSystem::lookThroughImplicitlyUnwrappedOptionalType(Type type) {
if (auto boundTy = type->getAs<BoundGenericEnumType>()) {
auto boundDecl = boundTy->getDecl();
if (boundDecl == TC.Context.getImplicitlyUnwrappedOptionalDecl() &&
!isPrivilegedAccessToImplicitlyUnwrappedOptional(DC, boundDecl))
return boundTy->getGenericArgs()[0];
}
return Type();
}
template <typename Fn>
Type simplifyTypeImpl(ConstraintSystem &cs, Type type, Fn getFixedTypeFn) {
return type.transform([&](Type type) -> Type {
if (auto tvt = dyn_cast<TypeVariableType>(type.getPointer()))
return getFixedTypeFn(tvt);
// If this is a dependent member type for which we end up simplifying
// the base to a non-type-variable, perform lookup.
if (auto depMemTy = dyn_cast<DependentMemberType>(type.getPointer())) {
// Simplify the base.
Type newBase = simplifyTypeImpl(cs, depMemTy->getBase(), getFixedTypeFn);
// If nothing changed, we're done.
if (newBase.getPointer() == depMemTy->getBase().getPointer())
return type;
// Dependent member types should only be created for associated types.
auto assocType = depMemTy->getAssocType();
assert(depMemTy->getAssocType() && "Expected associated type!");
// FIXME: It's kind of weird in general that we have to look
// through lvalue, inout and IUO types here
Type lookupBaseType = newBase->getWithoutSpecifierType();
auto *module = cs.DC->getParentModule();
// "Force" the IUO for substitution purposes. We can end up in
// this situation if we use the results of overload resolution
// as a generic type and the overload resolution resulted in an
// IUO-typed entity.
while (auto objectType =
lookupBaseType->getImplicitlyUnwrappedOptionalObjectType()) {
// If we're accessing a type member of the IUO itself,
// stop here. Ugh...
if (module->lookupConformance(lookupBaseType,
assocType->getProtocol(),
&cs.getTypeChecker())) {
break;
}
lookupBaseType = objectType;
}
if (lookupBaseType->mayHaveMembers()) {
auto subs = lookupBaseType->getContextSubstitutionMap(
cs.DC->getParentModule(),
assocType->getDeclContext());
auto result = assocType->getDeclaredInterfaceType().subst(subs);
if (result)
return result;
}
return DependentMemberType::get(lookupBaseType, assocType);
}
return type;
});
}
Type ConstraintSystem::simplifyType(Type type) {
if (!type->hasTypeVariable())
return type;
// Map type variables down to the fixed types of their representatives.
return simplifyTypeImpl(
*this, type,
[&](TypeVariableType *tvt) -> Type {
tvt = getRepresentative(tvt);
if (auto fixed = getFixedType(tvt)) {
return simplifyType(fixed);
}
return tvt;
});
}
Type Solution::simplifyType(Type type) const {
if (!type->hasTypeVariable())
return type;
// Map type variables to fixed types from bindings.
return simplifyTypeImpl(
getConstraintSystem(), type,
[&](TypeVariableType *tvt) -> Type {
auto known = typeBindings.find(tvt);
assert(known != typeBindings.end());
return known->second;
});
}
size_t Solution::getTotalMemory() const {
return sizeof(*this) + typeBindings.getMemorySize() +
overloadChoices.getMemorySize() +
ConstraintRestrictions.getMemorySize() +
llvm::capacity_in_bytes(Fixes) + DisjunctionChoices.getMemorySize() +
OpenedTypes.getMemorySize() + OpenedExistentialTypes.getMemorySize() +
(DefaultedConstraints.size() * sizeof(void *)) +
llvm::capacity_in_bytes(Conformances);
}
DeclName OverloadChoice::getName() const {
switch (getKind()) {
case OverloadChoiceKind::Decl:
case OverloadChoiceKind::DeclViaDynamic:
case OverloadChoiceKind::DeclViaBridge:
case OverloadChoiceKind::DeclViaUnwrappedOptional:
return getDecl()->getFullName();
case OverloadChoiceKind::KeyPathApplication: {
// TODO: This should probably produce subscript(keyPath:), but we
// don't currently pre-filter subscript overload sets by argument
// keywords, so "subscript" is still the name that keypath subscripts
// are looked up by.
return DeclBaseName::createSubscript();
}
case OverloadChoiceKind::BaseType:
case OverloadChoiceKind::TupleIndex:
llvm_unreachable("no name!");
}
llvm_unreachable("Unhandled OverloadChoiceKind in switch.");
}
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