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ConstraintSystem.cpp
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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 - 2018 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 "CSDiagnostics.h"
#include "TypeChecker.h"
#include "TypeCheckAvailability.h"
#include "TypeCheckType.h"
#include "swift/AST/Initializer.h"
#include "swift/AST/GenericEnvironment.h"
#include "swift/AST/ParameterList.h"
#include "swift/AST/ProtocolConformance.h"
#include "swift/AST/TypeCheckRequests.h"
#include "swift/Basic/Defer.h"
#include "swift/Basic/Statistic.h"
#include "swift/Sema/CSFix.h"
#include "swift/Sema/ConstraintGraph.h"
#include "swift/Sema/ConstraintSystem.h"
#include "swift/Sema/SolutionResult.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Format.h"
using namespace swift;
using namespace constraints;
using namespace inference;
#define DEBUG_TYPE "ConstraintSystem"
ExpressionTimer::ExpressionTimer(Expr *E, ConstraintSystem &CS)
: E(E),
Context(CS.getASTContext()),
StartTime(llvm::TimeRecord::getCurrentTime()),
PrintDebugTiming(CS.getASTContext().TypeCheckerOpts.DebugTimeExpressions),
PrintWarning(true) {
}
ExpressionTimer::~ExpressionTimer() {
auto elapsed = getElapsedProcessTimeInFractionalSeconds();
unsigned elapsedMS = static_cast<unsigned>(elapsed * 1000);
if (PrintDebugTiming) {
// 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 (!PrintWarning)
return;
const auto WarnLimit = getWarnLimit();
if (WarnLimit != 0 && elapsedMS >= WarnLimit && E->getLoc().isValid())
Context.Diags.diagnose(E->getLoc(), diag::debug_long_expression,
elapsedMS, WarnLimit)
.highlight(E->getSourceRange());
}
ConstraintSystem::ConstraintSystem(DeclContext *dc,
ConstraintSystemOptions options)
: Context(dc->getASTContext()), DC(dc), Options(options),
Arena(dc->getASTContext(), Allocator),
CG(*new ConstraintGraph(*this))
{
assert(DC && "context required");
// Respect the global debugging flag, but turn off debugging while
// parsing and loading other modules.
if (Context.TypeCheckerOpts.DebugConstraintSolver &&
DC->getParentModule()->isMainModule()) {
Options |= ConstraintSystemFlags::DebugConstraints;
}
if (Context.LangOpts.UseClangFunctionTypes)
Options |= ConstraintSystemFlags::UseClangFunctionTypes;
}
ConstraintSystem::~ConstraintSystem() {
delete &CG;
}
void ConstraintSystem::incrementScopeCounter() {
++CountScopes;
// FIXME: (transitional) increment the redundant "always-on" counter.
if (auto *Stats = getASTContext().Stats)
++Stats->getFrontendCounters().NumConstraintScopes;
}
void ConstraintSystem::incrementLeafScopes() {
if (auto *Stats = getASTContext().Stats)
++Stats->getFrontendCounters().NumLeafScopes;
}
bool ConstraintSystem::hasFreeTypeVariables() {
// Look for any free type variables.
return llvm::any_of(TypeVariables, [](const TypeVariableType *typeVar) {
return !typeVar->getImpl().hasRepresentativeOrFixed();
});
}
void ConstraintSystem::addTypeVariable(TypeVariableType *typeVar) {
TypeVariables.insert(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) {
SmallPtrSet<TypeVariableType *, 4> typeVars;
type->getTypeVariables(typeVars);
bool occurs = typeVars.count(typeVar);
if (involvesOtherTypeVariables) {
*involvesOtherTypeVariables =
occurs ? typeVars.size() > 1 : !typeVars.empty();
}
return occurs;
}
void ConstraintSystem::assignFixedType(TypeVariableType *typeVar, Type type,
bool updateState,
bool notifyBindingInference) {
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.
//
// 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->directlyAt<CollectionExpr>() ||
locator->directlyAt<LiteralExpr>())))
continue;
auto *literalProtocol = TypeChecker::getLiteralProtocol(
getASTContext(), castToExpr(locator->getAnchor()));
if (!literalProtocol)
continue;
// If the protocol has a default type, check it.
if (auto defaultType = TypeChecker::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);
}
}
break;
}
}
// Notify the constraint graph.
CG.bindTypeVariable(typeVar, type);
addTypeVariableConstraintsToWorkList(typeVar);
if (notifyBindingInference)
CG[typeVar].introduceToInference(type);
}
void ConstraintSystem::addTypeVariableConstraintsToWorkList(
TypeVariableType *typeVar) {
// Activate the constraints affected by a change to this type variable.
auto gatheringKind = ConstraintGraph::GatheringKind::AllMentions;
for (auto *constraint : CG.gatherConstraints(typeVar, gatheringKind))
if (!constraint->isActive())
activateConstraint(constraint);
}
/// 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)) {
auto ty = asd->getInterfaceType();
// Strip off a generic signature if we have one. This matches the logic
// for methods, and ensures that we don't take a protocol's generic
// signature into account for a subscript requirement.
if (auto *genericFn = ty->getAs<GenericFunctionType>()) {
ty = FunctionType::get(genericFn->getParams(), genericFn->getResult(),
genericFn->getExtInfo());
}
// Handle properties and subscripts, anchored by the getter's selector.
return std::make_tuple(asd->isStatic(), asd->getObjCGetterSelector(),
ty->getCanonicalType());
}
llvm_unreachable("Not a valid @objc member");
}
LookupResult &ConstraintSystem::lookupMember(Type base, DeclNameRef name) {
// Check whether we've already performed this lookup.
auto &result = MemberLookups[{base, name}];
if (result) return *result;
// Lookup the member.
result = TypeChecker::lookupMember(DC, base, name, defaultMemberLookupOptions);
// 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::DenseMap<std::tuple<char, ObjCSelector, CanType>, ValueDecl *> known;
bool anyRemovals = false;
for (const auto &entry : *result) {
auto *decl = entry.getValueDecl();
// Remove invalid declarations so the constraint solver doesn't need to
// cope with them.
if (decl->isInvalid()) {
anyRemovals = true;
continue;
}
// If this is the first entry with the signature, record it.
auto &uniqueEntry = known[getDynamicResultSignature(decl)];
if (!uniqueEntry) {
uniqueEntry = decl;
continue;
}
// We have duplication; note that we'll need to remove something,
anyRemovals = true;
// If the entry we recorded was unavailable but this new entry is not,
// replace the recorded entry with this one.
if (isDeclUnavailable(uniqueEntry) && !isDeclUnavailable(decl)) {
uniqueEntry = decl;
}
}
// If there's anything to remove, filter it out now.
if (anyRemovals) {
result->filter([&](LookupResultEntry entry, bool isOuter) -> bool {
auto *decl = entry.getValueDecl();
// Remove invalid declarations so the constraint solver doesn't need to
// cope with them.
if (decl->isInvalid())
return false;
return known[getDynamicResultSignature(decl)] == decl;
});
}
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 = getASTContext().getProtocol(
KnownProtocolKind::ExpressibleByFloatLiteral)) {
if (auto defaultType = TypeChecker::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];
}
bool ConstraintSystem::containsCodeCompletionLoc(Expr *expr) const {
SourceRange range = expr->getSourceRange();
if (range.isInvalid())
return false;
return Context.SourceMgr.rangeContainsCodeCompletionLoc(range);
}
ConstraintLocator *ConstraintSystem::getConstraintLocator(
ASTNode anchor, ArrayRef<ConstraintLocator::PathElement> path) {
auto summaryFlags = ConstraintLocator::getSummaryFlagsForPath(path);
return getConstraintLocator(anchor, path, summaryFlags);
}
ConstraintLocator *ConstraintSystem::getConstraintLocator(
ASTNode 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;
auto anchor = builder.getLocatorParts(path);
return getConstraintLocator(anchor, path, builder.getSummaryFlags());
}
ConstraintLocator *ConstraintSystem::getConstraintLocator(
ConstraintLocator *locator,
ArrayRef<ConstraintLocator::PathElement> newElts) {
auto oldPath = locator->getPath();
SmallVector<ConstraintLocator::PathElement, 4> newPath;
newPath.append(oldPath.begin(), oldPath.end());
newPath.append(newElts.begin(), newElts.end());
return getConstraintLocator(locator->getAnchor(), newPath);
}
ConstraintLocator *ConstraintSystem::getConstraintLocator(
const ConstraintLocatorBuilder &builder,
ArrayRef<ConstraintLocator::PathElement> newElts) {
SmallVector<ConstraintLocator::PathElement, 4> newPath;
auto anchor = builder.getLocatorParts(newPath);
newPath.append(newElts.begin(), newElts.end());
return getConstraintLocator(anchor, newPath);
}
ConstraintLocator *ConstraintSystem::getCalleeLocator(
ConstraintLocator *locator, bool lookThroughApply,
llvm::function_ref<Type(Expr *)> getType,
llvm::function_ref<Type(Type)> simplifyType,
llvm::function_ref<Optional<SelectedOverload>(ConstraintLocator *)>
getOverloadFor) {
auto anchor = locator->getAnchor();
assert(bool(anchor) && "Expected an anchor!");
auto path = locator->getPath();
{
// If we have a locator for a member found through key path dynamic member
// lookup, then we need to chop off the elements after the
// KeyPathDynamicMember element to get the callee locator.
auto iter = path.rbegin();
if (locator->findLast<LocatorPathElt::KeyPathDynamicMember>(iter)) {
auto newPath = path.drop_back(iter - path.rbegin());
return getConstraintLocator(anchor, newPath);
}
}
if (locator->findLast<LocatorPathElt::DynamicCallable>()) {
return getConstraintLocator(anchor, LocatorPathElt::ApplyFunction());
}
if (locator->isLastElement<LocatorPathElt::ArgumentAttribute>()) {
return getConstraintLocator(anchor, path.drop_back());
}
// If we have a locator that starts with a key path component element, we
// may have a callee given by a property or subscript component.
if (auto componentElt =
locator->getFirstElementAs<LocatorPathElt::KeyPathComponent>()) {
auto *kpExpr = castToExpr<KeyPathExpr>(anchor);
auto component = kpExpr->getComponents()[componentElt->getIndex()];
using ComponentKind = KeyPathExpr::Component::Kind;
switch (component.getKind()) {
case ComponentKind::UnresolvedSubscript:
case ComponentKind::Subscript:
// For a subscript the callee is given by 'component -> subscript member'.
return getConstraintLocator(
anchor, {*componentElt, ConstraintLocator::SubscriptMember});
case ComponentKind::UnresolvedProperty:
case ComponentKind::Property:
// For a property, the choice is just given by the component.
return getConstraintLocator(anchor, *componentElt);
case ComponentKind::TupleElement:
llvm_unreachable("Not implemented by CSGen");
break;
case ComponentKind::Invalid:
case ComponentKind::OptionalForce:
case ComponentKind::OptionalChain:
case ComponentKind::OptionalWrap:
case ComponentKind::Identity:
case ComponentKind::DictionaryKey:
// These components don't have any callee associated, so just continue.
break;
}
}
// Make sure we handle subscripts before looking at apply exprs. We don't
// want to return a subscript member locator for an expression such as x[](y),
// as its callee is not the subscript, but rather the function it returns.
if (isExpr<SubscriptExpr>(anchor))
return getConstraintLocator(anchor, ConstraintLocator::SubscriptMember);
auto getSpecialFnCalleeLoc = [&](Type fnTy) -> ConstraintLocator * {
fnTy = simplifyType(fnTy);
// It's okay for function type to contain type variable(s) e.g.
// opened generic function types, but not to be one.
assert(!fnTy->is<TypeVariableType>());
// For an apply of a metatype, we have a short-form constructor. Unlike
// other locators to callees, these are anchored on the apply expression
// rather than the function expr.
if (fnTy->is<AnyMetatypeType>()) {
return getConstraintLocator(anchor,
{LocatorPathElt::ApplyFunction(),
LocatorPathElt::ConstructorMember()});
}
// Handle an apply of a nominal type which supports callAsFunction.
if (fnTy->isCallableNominalType(DC)) {
return getConstraintLocator(anchor,
{LocatorPathElt::ApplyFunction(),
LocatorPathElt::ImplicitCallAsFunction()});
}
// Handling an apply for a nominal type that supports @dynamicCallable.
if (fnTy->hasDynamicCallableAttribute()) {
return getConstraintLocator(anchor, LocatorPathElt::ApplyFunction());
}
return nullptr;
};
if (lookThroughApply) {
if (auto *applyExpr = getAsExpr<ApplyExpr>(anchor)) {
auto *fnExpr = applyExpr->getFn();
// Handle special cases for applies of non-function types.
if (auto *loc = getSpecialFnCalleeLoc(getType(fnExpr)))
return loc;
// Otherwise fall through and look for locators anchored on the function
// expr. For CallExprs, this can look through things like parens and
// optional chaining.
if (auto *callExpr = getAsExpr<CallExpr>(anchor)) {
anchor = callExpr->getDirectCallee();
} else {
anchor = fnExpr;
}
}
}
if (auto *UDE = getAsExpr<UnresolvedDotExpr>(anchor)) {
return getConstraintLocator(
anchor, TypeChecker::getSelfForInitDelegationInConstructor(DC, UDE)
? ConstraintLocator::ConstructorMember
: ConstraintLocator::Member);
}
if (auto *UME = getAsExpr<UnresolvedMemberExpr>(anchor)) {
return getConstraintLocator(UME, ConstraintLocator::UnresolvedMember);
}
if (isExpr<MemberRefExpr>(anchor))
return getConstraintLocator(anchor, ConstraintLocator::Member);
if (isExpr<ObjectLiteralExpr>(anchor))
return getConstraintLocator(anchor, ConstraintLocator::ConstructorMember);
return getConstraintLocator(anchor);
}
/// Extend the given depth map by adding depths for all of the subexpressions
/// of the given expression.
static void extendDepthMap(
Expr *expr,
llvm::DenseMap<Expr *, std::pair<unsigned, Expr *>> &depthMap) {
class RecordingTraversal : public ASTWalker {
SmallVector<ClosureExpr *, 4> Closures;
public:
llvm::DenseMap<Expr *, std::pair<unsigned, Expr *>> &DepthMap;
unsigned Depth = 0;
explicit RecordingTraversal(
llvm::DenseMap<Expr *, std::pair<unsigned, Expr *>> &depthMap)
: DepthMap(depthMap) {}
std::pair<bool, Expr *> walkToExprPre(Expr *E) override {
DepthMap[E] = {Depth, Parent.getAsExpr()};
++Depth;
if (auto CE = dyn_cast<ClosureExpr>(E))
Closures.push_back(CE);
return { true, E };
}
Expr *walkToExprPost(Expr *E) override {
if (auto CE = dyn_cast<ClosureExpr>(E)) {
assert(Closures.back() == CE);
Closures.pop_back();
}
--Depth;
return E;
}
std::pair<bool, Stmt *> walkToStmtPre(Stmt *S) override {
if (auto RS = dyn_cast<ReturnStmt>(S)) {
// For return statements, treat the parent of the return expression
// as the closure itself.
if (RS->hasResult() && !Closures.empty()) {
llvm::SaveAndRestore<ParentTy> SavedParent(Parent, Closures.back());
auto E = RS->getResult();
E->walk(*this);
return { false, S };
}
}
return { true, S };
}
};
RecordingTraversal traversal(depthMap);
expr->walk(traversal);
}
Optional<std::pair<unsigned, Expr *>> ConstraintSystem::getExprDepthAndParent(
Expr *expr) {
// Bring the set of expression weights up to date.
while (NumInputExprsInWeights < InputExprs.size()) {
extendDepthMap(InputExprs[NumInputExprsInWeights], ExprWeights);
++NumInputExprsInWeights;
}
auto e = ExprWeights.find(expr);
if (e != ExprWeights.end())
return e->second;
return None;
}
Type ConstraintSystem::openUnboundGenericType(
GenericTypeDecl *decl, Type parentTy, ConstraintLocatorBuilder locator) {
if (parentTy) {
parentTy = replaceInferableTypesWithTypeVars(parentTy, locator);
}
// Open up the generic type.
OpenedTypeMap replacements;
openGeneric(decl->getDeclContext(), decl->getGenericSignature(), locator,
replacements);
recordOpenedTypes(locator, replacements);
if (parentTy) {
auto subs = parentTy->getContextSubstitutions(decl->getDeclContext());
for (auto pair : subs) {
auto found = replacements.find(
cast<GenericTypeParamType>(pair.first));
if (found == replacements.end()) {
// Can happen with invalid generic code.
continue;
}
addConstraint(ConstraintKind::Bind, found->second, pair.second,
locator);
}
}
// Map the generic parameters to their corresponding type variables.
llvm::SmallVector<Type, 2> arguments;
for (auto gp : decl->getInnermostGenericParamTypes()) {
auto found = replacements.find(
cast<GenericTypeParamType>(gp->getCanonicalType()));
assert(found != replacements.end() &&
"Missing generic parameter?");
arguments.push_back(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 TypeChecker::applyUnboundGenericArguments(
decl, parentTy, SourceLoc(),
TypeResolution::forContextual(DC, None, /*unboundTyOpener*/ nullptr,
/*placeholderHandler*/ nullptr),
arguments);
}
static void checkNestedTypeConstraints(ConstraintSystem &cs, Type type,
ConstraintLocatorBuilder locator) {
// If this is a type defined inside of constrainted extension, let's add all
// of the generic requirements to the constraint system to make sure that it's
// something we can use.
GenericTypeDecl *decl = nullptr;
Type parentTy;
SubstitutionMap subMap;
if (auto *NAT = dyn_cast<TypeAliasType>(type.getPointer())) {
decl = NAT->getDecl();
parentTy = NAT->getParent();
subMap = NAT->getSubstitutionMap();
} else if (auto *AGT = type->getAs<AnyGenericType>()) {
decl = AGT->getDecl();
parentTy = AGT->getParent();
// the context substitution map is fine here, since we can't be adding more
// info than that, unlike a typealias
}
if (!parentTy)
return;
// If this decl is generic, the constraints are handled when the generic
// parameters are applied, so we don't have to handle them here (which makes
// getting the right substitution maps easier).
if (!decl || decl->isGeneric())
return;
// struct A<T> {
// let foo: [T]
// }
//
// extension A : Codable where T: Codable {
// enum CodingKeys: String, CodingKey {
// case foo = "foo"
// }
// }
//
// Reference to `A.CodingKeys.foo` would point to `A` as an
// unbound generic type. Conditional requirements would be
// added when `A` is "opened". Les delay this check until then.
if (parentTy->hasUnboundGenericType())
return;
auto extension = dyn_cast<ExtensionDecl>(decl->getDeclContext());
if (extension && extension->isConstrainedExtension()) {
auto contextSubMap = parentTy->getContextSubstitutionMap(
extension->getParentModule(), extension->getSelfNominalTypeDecl());
if (!subMap) {
// The substitution map wasn't set above, meaning we should grab the map
// for the extension itself.
subMap = parentTy->getContextSubstitutionMap(extension->getParentModule(),
extension);
}
if (auto signature = decl->getGenericSignature()) {
cs.openGenericRequirements(
extension, signature, /*skipProtocolSelfConstraint*/ true, locator,
[&](Type type) {
// Why do we look in two substitution maps? We have to use the
// context substitution map to find types, because we need to
// avoid thinking about them when handling the constraints, or all
// the requirements in the signature become tautologies (if the
// extension has 'T == Int', subMap will map T -> Int, so the
// requirement becomes Int == Int no matter what the actual types
// are here). However, we need the conformances for the extension
// because the requirements might look like `T: P, T.U: Q`, where
// U is an associated type of protocol P.
return type.subst(QuerySubstitutionMap{contextSubMap},
LookUpConformanceInSubstitutionMap(subMap));
});
}
}
// And now make sure sure the parent is okay, for things like X<T>.Y.Z.
checkNestedTypeConstraints(cs, parentTy, locator);
}
Type ConstraintSystem::replaceInferableTypesWithTypeVars(
Type type, ConstraintLocatorBuilder locator) {
assert(!type->getCanonicalType()->hasTypeParameter());
if (!type->hasUnboundGenericType() && !type->hasPlaceholder())
return type;
type = type.transform([&](Type type) -> Type {
if (auto unbound = type->getAs<UnboundGenericType>()) {
return openUnboundGenericType(unbound->getDecl(), unbound->getParent(),
locator);
} else if (auto *placeholderTy = type->getAs<PlaceholderType>()) {
if (auto *placeholderRepr = placeholderTy->getOriginator()
.dyn_cast<PlaceholderTypeRepr *>()) {
return createTypeVariable(
getConstraintLocator(
locator, LocatorPathElt::PlaceholderType(placeholderRepr)),
TVO_CanBindToNoEscape | TVO_PrefersSubtypeBinding |
TVO_CanBindToHole);
}
}
return type;
});
if (!type)
return ErrorType::get(getASTContext());
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()));
// FIXME: This should be an assert, however protocol generic signatures
// drop outer generic parameters.
// assert(known != replacements.end());
if (known == replacements.end())
return ErrorType::get(getASTContext());
return known->second;
}
return type;
});
}
FunctionType *ConstraintSystem::openFunctionType(
AnyFunctionType *funcType,
ConstraintLocatorBuilder locator,
OpenedTypeMap &replacements,
DeclContext *outerDC) {
if (auto *genericFn = funcType->getAs<GenericFunctionType>()) {
auto signature = genericFn->getGenericSignature();
openGenericParameters(outerDC, signature, replacements, locator);
openGenericRequirements(
outerDC, signature, /*skipProtocolSelfConstraint=*/false, locator,
[&](Type type) -> Type { return openType(type, replacements); });
funcType = genericFn->substGenericArgs(
[&](Type type) { return openType(type, replacements); });
}
return funcType->castTo<FunctionType>();
}
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 st = type->getAs<StructType>()) {
auto &ctx = type->getASTContext();
return st->getDecl() == ctx.getAnyHashableDecl();
}
return false;
}
Type ConstraintSystem::getFixedTypeRecursive(Type type,
TypeMatchOptions &flags,
bool wantRValue) const {
if (wantRValue)
type = type->getRValueType();
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;
// Once we've simplified a dependent member type, we need to generate a
// new constraint.
flags |= TMF_GenerateConstraints;
return getFixedTypeRecursive(newType, flags, wantRValue);
}
if (auto typeVar = type->getAs<TypeVariableType>()) {
if (auto fixed = getFixedType(typeVar))
return getFixedTypeRecursive(fixed, flags, wantRValue);
return getRepresentative(typeVar);
}
return type;
}
TypeVariableType *ConstraintSystem::isRepresentativeFor(
TypeVariableType *typeVar, ConstraintLocator::PathElementKind kind) const {
// We only attempt to look for this if type variable is
// a representative.
if (getRepresentative(typeVar) != typeVar)
return nullptr;
auto &CG = getConstraintGraph();
auto result = CG.lookupNode(typeVar);
auto equivalence = result.first.getEquivalenceClass();
auto member = llvm::find_if(equivalence, [=](TypeVariableType *eq) {
auto *loc = eq->getImpl().getLocator();
if (!loc)
return false;
auto path = loc->getPath();
return !path.empty() && path.back().getKind() == kind;
});
if (member == equivalence.end())
return nullptr;
return *member;
}
static Optional<std::pair<VarDecl *, Type>>
getPropertyWrapperInformationFromOverload(
SelectedOverload resolvedOverload, DeclContext *DC,
llvm::function_ref<Optional<std::pair<VarDecl *, Type>>(VarDecl *)>
getInformation) {
if (auto *decl =
dyn_cast_or_null<VarDecl>(resolvedOverload.choice.getDeclOrNull())) {
if (auto declInformation = getInformation(decl)) {
Type type;
VarDecl *memberDecl;
std::tie(memberDecl, type) = *declInformation;
if (Type baseType = resolvedOverload.choice.getBaseType()) {
type =
baseType->getTypeOfMember(DC->getParentModule(), memberDecl, type);
}
return std::make_pair(decl, type);
}
}
return None;
}
Optional<std::pair<VarDecl *, Type>>
ConstraintSystem::getPropertyWrapperProjectionInfo(
SelectedOverload resolvedOverload) {
return getPropertyWrapperInformationFromOverload(
resolvedOverload, DC,
[](VarDecl *decl) -> Optional<std::pair<VarDecl *, Type>> {
if (!decl->hasAttachedPropertyWrapper())
return None;
auto projectionVar = decl->getPropertyWrapperProjectionVar();
if (!projectionVar)
return None;
return std::make_pair(projectionVar,
projectionVar->getInterfaceType());
});
}
Optional<std::pair<VarDecl *, Type>>
ConstraintSystem::getPropertyWrapperInformation(
SelectedOverload resolvedOverload) {
return getPropertyWrapperInformationFromOverload(
resolvedOverload, DC,
[](VarDecl *decl) -> Optional<std::pair<VarDecl *, Type>> {
if (!decl->hasAttachedPropertyWrapper())
return None;