averello/swift-mirror
1
0
Fork 0
mirror of https://github.com/apple/swift.git synced 2025-12-14 20:36:38 +01:00
Code Issues Packages Projects Releases Wiki Activity
Files
4c0b58096e881ec775b8edab939250ccada94c31
swift-mirror/lib/Sema/CSGen.cpp

5354 lines
204 KiB
C++
Raw Blame History

//===--- CSGen.cpp - Constraint Generator ---------------------------------===//
//
// 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 constraint generation for the type checker.
//
//===----------------------------------------------------------------------===//
#include "TypeCheckConcurrency.h"
#include "TypeCheckDecl.h"
#include "TypeCheckMacros.h"
#include "TypeCheckType.h"
#include "TypeChecker.h"
#include "swift/AST/ASTVisitor.h"
#include "swift/AST/ASTWalker.h"
#include "swift/AST/ConformanceLookup.h"
#include "swift/AST/Expr.h"
#include "swift/AST/GenericSignature.h"
#include "swift/AST/GenericEnvironment.h"
#include "swift/AST/ParameterList.h"
#include "swift/AST/PrettyStackTrace.h"
#include "swift/AST/SubstitutionMap.h"
#include "swift/AST/TypeCheckRequests.h"
#include "swift/Basic/Assertions.h"
#include "swift/Sema/ConstraintGraph.h"
#include "swift/Sema/ConstraintSystem.h"
#include "swift/Sema/IDETypeChecking.h"
#include "swift/Sema/PreparedOverload.h"
#include "swift/Subsystems.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringSwitch.h"
#include <utility>
using namespace swift;
using namespace swift::constraints;
static bool isArithmeticOperatorDecl(ValueDecl *vd) {
return vd && vd->getBaseIdentifier().isArithmeticOperator();
}
static bool mergeRepresentativeEquivalenceClasses(ConstraintSystem &CS,
TypeVariableType* tyvar1,
TypeVariableType* tyvar2) {
if (tyvar1 && tyvar2) {
auto rep1 = CS.getRepresentative(tyvar1);
auto rep2 = CS.getRepresentative(tyvar2);
if (rep1 != rep2) {
auto fixedType2 = CS.getFixedType(rep2);
// If the there exists fixed type associated with the second
// type variable, and we simply merge two types together it would
// mean that portion of the constraint graph previously associated
// with that (second) variable is going to be disconnected from its
// new equivalence class, which is going to lead to incorrect solutions,
// so we need to make sure to re-bind fixed to the new representative.
if (fixedType2) {
CS.addConstraint(ConstraintKind::Bind, fixedType2, rep1,
rep1->getImpl().getLocator());
}
CS.mergeEquivalenceClasses(rep1, rep2, /*updateWorkList*/ false);
return true;
}
}
return false;
}
namespace {
/// Internal struct for tracking information about types within a series
/// of "linked" expressions. (Such as a chain of binary operator invocations.)
struct LinkedTypeInfo {
bool hasLiteral = false;
llvm::SmallSet<TypeBase*, 16> collectedTypes;
llvm::SmallVector<BinaryExpr *, 4> binaryExprs;
};
/// Walks an expression sub-tree, and collects information about expressions
/// whose types are mutually dependent upon one another.
class LinkedExprCollector : public ASTWalker {
llvm::SmallVectorImpl<Expr*> &LinkedExprs;
public:
LinkedExprCollector(llvm::SmallVectorImpl<Expr *> &linkedExprs)
: LinkedExprs(linkedExprs) {}
MacroWalking getMacroWalkingBehavior() const override {
return MacroWalking::Arguments;
}
PreWalkResult<Expr *> walkToExprPre(Expr *expr) override {
if (isa<ClosureExpr>(expr))
return Action::SkipNode(expr);
// Store top-level binary exprs for further analysis.
if (isa<BinaryExpr>(expr) ||
// Literal exprs are contextually typed, so store them off as well.
isa<LiteralExpr>(expr) ||
// We'd like to look at the elements of arrays and dictionaries.
isa<ArrayExpr>(expr) ||
isa<DictionaryExpr>(expr) ||
// assignment expression can involve anonymous closure parameters
// as source and destination, so it's beneficial for diagnostics if
// we look at the assignment.
isa<AssignExpr>(expr)) {
LinkedExprs.push_back(expr);
return Action::SkipNode(expr);
}
return Action::Continue(expr);
}
/// Ignore statements.
PreWalkResult<Stmt *> walkToStmtPre(Stmt *stmt) override {
return Action::SkipNode(stmt);
}
/// Ignore declarations.
PreWalkAction walkToDeclPre(Decl *decl) override {
return Action::SkipNode();
}
/// Ignore patterns.
PreWalkResult<Pattern *> walkToPatternPre(Pattern *pat) override {
return Action::SkipNode(pat);
}
/// Ignore types.
PreWalkAction walkToTypeReprPre(TypeRepr *T) override {
return Action::SkipNode();
}
};
/// Given a collection of "linked" expressions, analyzes them for
/// commonalities regarding their types. This will help us compute a
/// "best common type" from the expression types.
class LinkedExprAnalyzer : public ASTWalker {
LinkedTypeInfo &LTI;
ConstraintSystem &CS;
public:
LinkedExprAnalyzer(LinkedTypeInfo &lti, ConstraintSystem &cs) :
LTI(lti), CS(cs) {}
MacroWalking getMacroWalkingBehavior() const override {
return MacroWalking::Arguments;
}
PreWalkResult<Expr *> walkToExprPre(Expr *expr) override {
if (isa<LiteralExpr>(expr)) {
LTI.hasLiteral = true;
return Action::SkipNode(expr);
}
if (isa<CollectionExpr>(expr)) {
return Action::Continue(expr);
}
if (auto UDE = dyn_cast<UnresolvedDotExpr>(expr)) {
if (CS.hasType(UDE))
LTI.collectedTypes.insert(CS.getType(UDE).getPointer());
// Don't recurse into the base expression.
return Action::SkipNode(expr);
}
if (isa<ClosureExpr>(expr)) {
return Action::SkipNode(expr);
}
if (auto FVE = dyn_cast<ForceValueExpr>(expr)) {
LTI.collectedTypes.insert(CS.getType(FVE).getPointer());
return Action::SkipNode(expr);
}
if (auto DRE = dyn_cast<DeclRefExpr>(expr)) {
if (isa<VarDecl>(DRE->getDecl())) {
if (CS.hasType(DRE)) {
LTI.collectedTypes.insert(CS.getType(DRE).getPointer());
}
return Action::SkipNode(expr);
}
}
// In the case of a function application, we would have already captured
// the return type during constraint generation, so there's no use in
// looking any further.
if (isa<ApplyExpr>(expr) &&
!(isa<BinaryExpr>(expr) || isa<PrefixUnaryExpr>(expr) ||
isa<PostfixUnaryExpr>(expr))) {
return Action::SkipNode(expr);
}
if (auto *binaryExpr = dyn_cast<BinaryExpr>(expr)) {
LTI.binaryExprs.push_back(binaryExpr);
}
if (auto favoredType = CS.getFavoredType(expr)) {
LTI.collectedTypes.insert(favoredType);
return Action::SkipNode(expr);
}
// Optimize branches of a conditional expression separately.
if (auto IE = dyn_cast<TernaryExpr>(expr)) {
CS.optimizeConstraints(IE->getCondExpr());
CS.optimizeConstraints(IE->getThenExpr());
CS.optimizeConstraints(IE->getElseExpr());
return Action::SkipNode(expr);
}
// For exprs of a tuple, avoid favoring. (We need to allow for cases like
// (Int, Int32).)
if (isa<TupleExpr>(expr)) {
return Action::SkipNode(expr);
}
// Coercion exprs have a rigid type, so there's no use in gathering info
// about them.
if (auto *coercion = dyn_cast<CoerceExpr>(expr)) {
// Let's not collect information about types initialized by
// coercions just like we don't for regular initializer calls,
// because that might lead to overly eager type variable merging.
if (!coercion->isLiteralInit())
LTI.collectedTypes.insert(CS.getType(expr).getPointer());
return Action::SkipNode(expr);
}
// Don't walk into subscript expressions - to do so would risk factoring
// the index expression into edge contraction. (We don't want to do this
// if the index expression is a literal type that differs from the return
// type of the subscript operation.)
if (isa<SubscriptExpr>(expr) || isa<DynamicLookupExpr>(expr)) {
return Action::SkipNode(expr);
}
// Don't walk into unresolved member expressions - we avoid merging type
// variables inside UnresolvedMemberExpr and those outside, since they
// should be allowed to behave independently in CS.
if (isa<UnresolvedMemberExpr>(expr)) {
return Action::SkipNode(expr);
}
return Action::Continue(expr);
}
/// Ignore statements.
PreWalkResult<Stmt *> walkToStmtPre(Stmt *stmt) override {
return Action::SkipNode(stmt);
}
/// Ignore declarations.
PreWalkAction walkToDeclPre(Decl *decl) override {
return Action::SkipNode();
}
/// Ignore patterns.
PreWalkResult<Pattern *> walkToPatternPre(Pattern *pat) override {
return Action::SkipNode(pat);
}
/// Ignore types.
PreWalkAction walkToTypeReprPre(TypeRepr *T) override {
return Action::SkipNode();
}
};
/// For a given expression, given information that is global to the
/// expression, attempt to derive a favored type for it.
void computeFavoredTypeForExpr(Expr *expr, ConstraintSystem &CS) {
LinkedTypeInfo lti;
expr->walk(LinkedExprAnalyzer(lti, CS));
// Check whether we can proceed with favoring.
if (llvm::any_of(lti.binaryExprs, [](const BinaryExpr *op) {
auto *ODRE = dyn_cast<OverloadedDeclRefExpr>(op->getFn());
if (!ODRE)
return false;
// Attempting to favor based on operand types is wrong for
// nil-coalescing operator.
auto identifier = ODRE->getDecls().front()->getBaseIdentifier();
return identifier.isNilCoalescingOperator();
})) {
return;
}
if (lti.collectedTypes.size() == 1) {
// TODO: Compute the BCT.
// It's only useful to favor the type instead of
// binding it directly to arguments/result types,
// which means in case it has been miscalculated
// solver can still make progress.
auto favoredTy = (*lti.collectedTypes.begin())->getWithoutSpecifierType();
CS.setFavoredType(expr, favoredTy.getPointer());
// If we have a chain of identical binop expressions with homogeneous
// argument types, we can directly simplify the associated constraint
// graph.
auto simplifyBinOpExprTyVars = [&]() {
// Don't attempt to do linking if there are
// literals intermingled with other inferred types.
if (lti.hasLiteral)
return;
for (auto binExp1 : lti.binaryExprs) {
for (auto binExp2 : lti.binaryExprs) {
if (binExp1 == binExp2)
continue;
auto fnTy1 = CS.getType(binExp1)->getAs<TypeVariableType>();
auto fnTy2 = CS.getType(binExp2)->getAs<TypeVariableType>();
if (!(fnTy1 && fnTy2))
return;
auto ODR1 = dyn_cast<OverloadedDeclRefExpr>(binExp1->getFn());
auto ODR2 = dyn_cast<OverloadedDeclRefExpr>(binExp2->getFn());
if (!(ODR1 && ODR2))
return;
// TODO: We currently limit this optimization to known arithmetic
// operators, but we should be able to broaden this out to
// logical operators as well.
if (!isArithmeticOperatorDecl(ODR1->getDecls()[0]))
return;
if (ODR1->getDecls()[0]->getBaseName() !=
ODR2->getDecls()[0]->getBaseName())
return;
// All things equal, we can merge the tyvars for the function
// types.
auto rep1 = CS.getRepresentative(fnTy1);
auto rep2 = CS.getRepresentative(fnTy2);
if (rep1 != rep2) {
CS.mergeEquivalenceClasses(rep1, rep2,
/*updateWorkList*/ false);
}
auto odTy1 = CS.getType(ODR1)->getAs<TypeVariableType>();
auto odTy2 = CS.getType(ODR2)->getAs<TypeVariableType>();
if (odTy1 && odTy2) {
auto odRep1 = CS.getRepresentative(odTy1);
auto odRep2 = CS.getRepresentative(odTy2);
// Since we'll be choosing the same overload, we can merge
// the overload tyvar as well.
if (odRep1 != odRep2)
CS.mergeEquivalenceClasses(odRep1, odRep2,
/*updateWorkList*/ false);
}
}
}
};
simplifyBinOpExprTyVars();
}
}
/// Determine whether the given parameter type and argument should be
/// "favored" because they match exactly.
bool isFavoredParamAndArg(ConstraintSystem &CS, Type paramTy, Type argTy,
Type otherArgTy = Type()) {
// Determine the argument type.
argTy = argTy->getWithoutSpecifierType();
// Do the types match exactly?
if (paramTy->isEqual(argTy))
return true;
// Don't favor narrowing conversions.
if (argTy->isDouble() && paramTy->isCGFloat())
return false;
llvm::SmallSetVector<ProtocolDecl *, 2> literalProtos;
if (auto argTypeVar = argTy->getAs<TypeVariableType>()) {
auto constraints = CS.getConstraintGraph().gatherNearbyConstraints(
argTypeVar,
[](Constraint *constraint) {
return constraint->getKind() == ConstraintKind::LiteralConformsTo;
});
for (auto constraint : constraints) {
literalProtos.insert(constraint->getProtocol());
}
}
// Dig out the second argument type.
if (otherArgTy)
otherArgTy = otherArgTy->getWithoutSpecifierType();
for (auto literalProto : literalProtos) {
// If there is another, concrete argument, check whether it's type
// conforms to the literal protocol and test against it directly.
// This helps to avoid 'widening' the favored type to the default type for
// the literal.
if (otherArgTy && otherArgTy->getAnyNominal()) {
if (otherArgTy->isEqual(paramTy) &&
CS.lookupConformance(otherArgTy, literalProto)) {
return true;
}
} else if (Type defaultType =
TypeChecker::getDefaultType(literalProto, CS.DC)) {
// If there is a default type for the literal protocol, check whether
// it is the same as the parameter type.
// Check whether there is a default type to compare against.
if (paramTy->isEqual(defaultType) ||
(defaultType->isDouble() && paramTy->isCGFloat()))
return true;
}
}
return false;
}
/// Favor certain overloads in a call based on some basic analysis
/// of the overload set and call arguments.
///
/// \param expr The application.
/// \param isFavored Determine whether the given overload is favored, passing
/// it the "effective" overload type when it's being called.
/// \param mustConsider If provided, a function to detect the presence of
/// overloads which inhibit any overload from being favored.
void favorCallOverloads(ApplyExpr *expr,
ConstraintSystem &CS,
llvm::function_ref<bool(ValueDecl *, Type)> isFavored,
std::function<bool(ValueDecl *)>
mustConsider = nullptr) {
// Find the type variable associated with the function, if any.
auto tyvarType = CS.getType(expr->getFn())->getAs<TypeVariableType>();
if (!tyvarType || CS.getFixedType(tyvarType))
return;
// This type variable is only currently associated with the function
// being applied, and the only constraint attached to it should
// be the disjunction constraint for the overload group.
auto disjunction = CS.getUnboundBindOverloadDisjunction(tyvarType);
if (!disjunction)
return;
// Find the favored constraints and mark them.
SmallVector<Constraint *, 4> newlyFavoredConstraints;
unsigned numFavoredConstraints = 0;
Constraint *firstFavored = nullptr;
for (auto constraint : disjunction->getNestedConstraints()) {
auto *decl = constraint->getOverloadChoice().getDeclOrNull();
if (!decl)
continue;
if (mustConsider && mustConsider(decl)) {
// Roll back any constraints we favored.
for (auto favored : newlyFavoredConstraints)
favored->setFavored(false);
return;
}
Type overloadType = CS.getEffectiveOverloadType(
constraint->getLocator(), constraint->getOverloadChoice(),
/*allowMembers=*/true, CS.DC);
if (!overloadType)
continue;
if (!CS.isDeclUnavailable(decl, constraint->getLocator()) &&
!decl->getAttrs().hasAttribute<DisfavoredOverloadAttr>() &&
isFavored(decl, overloadType)) {
// If we might need to roll back the favored constraints, keep
// track of those we are favoring.
if (mustConsider && !constraint->isFavored())
newlyFavoredConstraints.push_back(constraint);
constraint->setFavored();
++numFavoredConstraints;
if (!firstFavored)
firstFavored = constraint;
}
}
// If there was one favored constraint, set the favored type based on its
// result type.
if (numFavoredConstraints == 1) {
auto overloadChoice = firstFavored->getOverloadChoice();
auto overloadType = CS.getEffectiveOverloadType(
firstFavored->getLocator(), overloadChoice, /*allowMembers=*/true,
CS.DC);
auto resultType = overloadType->castTo<AnyFunctionType>()->getResult();
if (!resultType->hasTypeParameter())
CS.setFavoredType(expr, resultType.getPointer());
}
}
/// Return a pair, containing the total parameter count of a function, coupled
/// with the number of non-default parameters.
std::pair<size_t, size_t> getParamCount(ValueDecl *VD) {
auto fTy = VD->getInterfaceType()->castTo<AnyFunctionType>();
size_t nOperands = fTy->getParams().size();
size_t nNoDefault = 0;
if (auto AFD = dyn_cast<AbstractFunctionDecl>(VD)) {
assert(!AFD->hasImplicitSelfDecl());
for (auto param : *AFD->getParameters()) {
if (!param->isDefaultArgument())
++nNoDefault;
}
} else {
nNoDefault = nOperands;
}
return { nOperands, nNoDefault };
}
bool hasContextuallyFavorableResultType(AnyFunctionType *choice,
Type contextualTy) {
// No restrictions of what result could be.
if (!contextualTy)
return true;
auto resultTy = choice->getResult();
// Result type of the call matches expected contextual type.
return contextualTy->isEqual(resultTy);
}
/// Favor unary operator constraints where we have exact matches
/// for the operand and contextual type.
void favorMatchingUnaryOperators(ApplyExpr *expr,
ConstraintSystem &CS) {
auto *unaryArg = expr->getArgs()->getUnaryExpr();
assert(unaryArg);
// Determine whether the given declaration is favored.
auto isFavoredDecl = [&](ValueDecl *value, Type type) -> bool {
auto fnTy = type->getAs<AnyFunctionType>();
if (!fnTy)
return false;
auto params = fnTy->getParams();
if (params.size() != 1)
return false;
auto paramTy = params[0].getPlainType();
auto argTy = CS.getType(unaryArg);
// There are no CGFloat overloads on some of the unary operators, so
// in order to preserve current behavior, let's not favor overloads
// which would result in conversion from CGFloat to Double; otherwise
// it would lead to ambiguities.
if (argTy->isCGFloat() && paramTy->isDouble())
return false;
return isFavoredParamAndArg(CS, paramTy, argTy) &&
hasContextuallyFavorableResultType(
fnTy,
CS.getContextualType(expr, /*forConstraint=*/false));
};
favorCallOverloads(expr, CS, isFavoredDecl);
}
void favorMatchingOverloadExprs(ApplyExpr *expr,
ConstraintSystem &CS) {
// Find the argument type.
size_t nArgs = expr->getArgs()->size();
auto fnExpr = expr->getFn();
auto mustConsiderVariadicGenericOverloads = [&](ValueDecl *overload) {
if (overload->getAttrs().hasAttribute<DisfavoredOverloadAttr>())
return false;
auto genericContext = overload->getAsGenericContext();
if (!genericContext)
return false;
auto *GPL = genericContext->getGenericParams();
if (!GPL)
return false;
return llvm::any_of(GPL->getParams(),
[&](const GenericTypeParamDecl *GP) {
return GP->isParameterPack();
});
};
// Check to ensure that we have an OverloadedDeclRef, and that we're not
// favoring multiple overload constraints. (Otherwise, in this case
// favoring is useless.
if (auto ODR = dyn_cast<OverloadedDeclRefExpr>(fnExpr)) {
bool haveMultipleApplicableOverloads = false;
for (auto VD : ODR->getDecls()) {
if (VD->getInterfaceType()->is<AnyFunctionType>()) {
auto nParams = getParamCount(VD);
if (nArgs == nParams.first) {
if (haveMultipleApplicableOverloads) {
return;
} else {
haveMultipleApplicableOverloads = true;
}
}
}
}
// Determine whether the given declaration is favored.
auto isFavoredDecl = [&](ValueDecl *value, Type type) -> bool {
// We want to consider all options for calls that might contain the code
// completion location, as missing arguments after the completion
// location are valid (since it might be that they just haven't been
// written yet).
if (CS.isForCodeCompletion())
return false;
if (!type->is<AnyFunctionType>())
return false;
auto paramCount = getParamCount(value);
return nArgs == paramCount.first ||
nArgs == paramCount.second;
};
favorCallOverloads(expr, CS, isFavoredDecl,
mustConsiderVariadicGenericOverloads);
}
// We only currently perform favoring for unary args.
auto *unaryArg = expr->getArgs()->getUnlabeledUnaryExpr();
if (!unaryArg)
return;
if (auto favoredTy = CS.getFavoredType(unaryArg)) {
// Determine whether the given declaration is favored.
auto isFavoredDecl = [&](ValueDecl *value, Type type) -> bool {
auto fnTy = type->getAs<AnyFunctionType>();
if (!fnTy || fnTy->getParams().size() != 1)
return false;
return favoredTy->isEqual(fnTy->getParams()[0].getPlainType());
};
// This is a hack to ensure we always consider the protocol requirement
// itself when calling something that has a default implementation in an
// extension. Otherwise, the extension method might be favored if we're
// inside an extension context, since any archetypes in the parameter
// list could match exactly.
auto mustConsider = [&](ValueDecl *value) -> bool {
return isa<ProtocolDecl>(value->getDeclContext()) ||
mustConsiderVariadicGenericOverloads(value);
};
favorCallOverloads(expr, CS, isFavoredDecl, mustConsider);
}
}
/// Favor binary operator constraints where we have exact matches
/// for the operands and contextual type.
void favorMatchingBinaryOperators(ApplyExpr *expr, ConstraintSystem &CS) {
// If we're generating constraints for a binary operator application,
// there are two special situations to consider:
// 1. If the type checker has any newly created functions with the
// operator's name. If it does, the overloads were created after the
// associated overloaded id expression was created, and we'll need to
// add a new disjunction constraint for the new set of overloads.
// 2. If any component argument expressions (nested or otherwise) are
// literals, we can favor operator overloads whose argument types are
// identical to the literal type, or whose return types are identical
// to any contextual type associated with the application expression.
// Find the argument types.
auto *args = expr->getArgs();
auto *lhs = args->getExpr(0);
auto *rhs = args->getExpr(1);
auto firstArgTy = CS.getType(lhs);
auto secondArgTy = CS.getType(rhs);
auto isOptionalWithMatchingObjectType = [](Type optional,
Type object) -> bool {
if (auto objTy = optional->getRValueType()->getOptionalObjectType())
return objTy->getRValueType()->isEqual(object->getRValueType());
return false;
};
auto isPotentialForcingOpportunity = [&](Type first, Type second) -> bool {
return isOptionalWithMatchingObjectType(first, second) ||
isOptionalWithMatchingObjectType(second, first);
};
// Determine whether the given declaration is favored.
auto isFavoredDecl = [&](ValueDecl *value, Type type) -> bool {
auto fnTy = type->getAs<AnyFunctionType>();
if (!fnTy)
return false;
auto firstFavoredTy = CS.getFavoredType(lhs);
auto secondFavoredTy = CS.getFavoredType(rhs);
auto favoredExprTy = CS.getFavoredType(expr);
if (isArithmeticOperatorDecl(value)) {
// If the parent has been favored on the way down, propagate that
// information to its children.
// TODO: This is only valid for arithmetic expressions.
if (!firstFavoredTy) {
CS.setFavoredType(lhs, favoredExprTy);
firstFavoredTy = favoredExprTy;
}
if (!secondFavoredTy) {
CS.setFavoredType(rhs, favoredExprTy);
secondFavoredTy = favoredExprTy;
}
}
auto params = fnTy->getParams();
if (params.size() != 2)
return false;
auto firstParamTy = params[0].getOldType();
auto secondParamTy = params[1].getOldType();
auto contextualTy = CS.getContextualType(expr, /*forConstraint=*/false);
// Avoid favoring overloads that would require narrowing conversion
// to match the arguments.
{
if (firstArgTy->isDouble() && firstParamTy->isCGFloat())
return false;
if (secondArgTy->isDouble() && secondParamTy->isCGFloat())
return false;
}
return (isFavoredParamAndArg(CS, firstParamTy, firstArgTy, secondArgTy) ||
isFavoredParamAndArg(CS, secondParamTy, secondArgTy,
firstArgTy)) &&
firstParamTy->isEqual(secondParamTy) &&
!isPotentialForcingOpportunity(firstArgTy, secondArgTy) &&
hasContextuallyFavorableResultType(fnTy, contextualTy);
};
favorCallOverloads(expr, CS, isFavoredDecl);
}
/// If \p expr is a call and that call contains the code completion token,
/// add the expressions of all arguments after the code completion token to
/// \p ignoredArguments.
/// Otherwise, returns an empty vector.
/// Assumes that we are solving for code completion.
void getArgumentsAfterCodeCompletionToken(
Expr *expr, ConstraintSystem &CS,
SmallVectorImpl<Expr *> &ignoredArguments) {
assert(CS.isForCodeCompletion());
/// Don't ignore the rhs argument if the code completion token is the lhs of
/// an operator call. Main use case is the implicit `<complete> ~= $match`
/// call created for pattern matching, in which we need to type-check
/// `$match` to get a contextual type for `<complete>`
if (isa<BinaryExpr>(expr)) {
return;
}
auto args = expr->getArgs();
auto argInfo = getCompletionArgInfo(expr, CS);
if (!args || !argInfo) {
return;
}
for (auto argIndex : indices(*args)) {
if (argInfo->isBefore(argIndex)) {
ignoredArguments.push_back(args->get(argIndex).getExpr());
}
}
}
class ConstraintOptimizer : public ASTWalker {
ConstraintSystem &CS;
public:
ConstraintOptimizer(ConstraintSystem &cs) :
CS(cs) {}
MacroWalking getMacroWalkingBehavior() const override {
return MacroWalking::Arguments;
}
PreWalkResult<Expr *> walkToExprPre(Expr *expr) override {
if (CS.isArgumentIgnoredForCodeCompletion(expr)) {
return Action::SkipNode(expr);
}
if (auto applyExpr = dyn_cast<ApplyExpr>(expr)) {
if (isa<PrefixUnaryExpr>(applyExpr) ||
isa<PostfixUnaryExpr>(applyExpr)) {
favorMatchingUnaryOperators(applyExpr, CS);
} else if (isa<BinaryExpr>(applyExpr)) {
favorMatchingBinaryOperators(applyExpr, CS);
} else {
favorMatchingOverloadExprs(applyExpr, CS);
}
}
// If the paren expr has a favored type, and the subExpr doesn't,
// propagate downwards. Otherwise, propagate upwards.
if (auto parenExpr = dyn_cast<ParenExpr>(expr)) {
if (!CS.getFavoredType(parenExpr->getSubExpr())) {
CS.setFavoredType(parenExpr->getSubExpr(),
CS.getFavoredType(parenExpr));
} else if (!CS.getFavoredType(parenExpr)) {
CS.setFavoredType(parenExpr,
CS.getFavoredType(parenExpr->getSubExpr()));
}
}
if (isa<ClosureExpr>(expr))
return Action::SkipNode(expr);
return Action::Continue(expr);
}
/// Ignore statements.
PreWalkResult<Stmt *> walkToStmtPre(Stmt *stmt) override {
return Action::SkipNode(stmt);
}
/// Ignore declarations.
PreWalkAction walkToDeclPre(Decl *decl) override {
return Action::SkipNode();
}
};
} // end anonymous namespace
void TypeVarRefCollector::inferTypeVars(Decl *D) {
// We're only interested in VarDecls.
if (!isa_and_nonnull<VarDecl>(D))
return;
auto ty = CS.getTypeIfAvailable(D);
if (!ty)
return;
SmallPtrSet<TypeVariableType *, 4> typeVars;
ty->getTypeVariables(typeVars);
TypeVars.insert(typeVars.begin(), typeVars.end());
}
void TypeVarRefCollector::inferTypeVars(PackExpansionExpr *E) {
auto expansionType = CS.getType(E)->castTo<PackExpansionType>();
SmallPtrSet<TypeVariableType *, 4> referencedVars;
expansionType->getTypeVariables(referencedVars);
TypeVars.insert(referencedVars.begin(), referencedVars.end());
}
ASTWalker::PreWalkResult<Expr *>
TypeVarRefCollector::walkToExprPre(Expr *expr) {
if (isa<ClosureExpr>(expr))
DCDepth += 1;
if (auto *DRE = dyn_cast<DeclRefExpr>(expr))
inferTypeVars(DRE->getDecl());
// FIXME: We can see UnresolvedDeclRefExprs here because we don't walk into
// patterns when running preCheckTarget, since we don't resolve patterns
// until CSGen. We ought to consider moving pattern resolution into
// pre-checking, which would allow us to pre-check patterns normally.
if (auto *declRef = dyn_cast<UnresolvedDeclRefExpr>(expr)) {
auto name = declRef->getName();
auto loc = declRef->getLoc();
if (name.isSimpleName() && loc.isValid()) {
auto *SF = CS.DC->getParentSourceFile();
auto *D = ASTScope::lookupSingleLocalDecl(SF, name.getFullName(), loc);
inferTypeVars(D);
}
}
if (auto *packElement = getAsExpr<PackElementExpr>(expr)) {
// If expansion hasn't been established yet, it means that pack expansion
// appears inside of this closure.
if (auto *outerExpansion = CS.getPackElementExpansion(packElement))
inferTypeVars(outerExpansion);
}
return Action::Continue(expr);
}
ASTWalker::PostWalkResult<Expr *>
TypeVarRefCollector::walkToExprPost(Expr *expr) {
if (isa<ClosureExpr>(expr))
DCDepth -= 1;
return Action::Continue(expr);
}
ASTWalker::PreWalkResult<Stmt *>
TypeVarRefCollector::walkToStmtPre(Stmt *stmt) {
// If we have a return without any intermediate DeclContexts in a ClosureExpr,
// we need to include any type variables in the closure's result type, since
// the conjunction will generate constraints using that type. We don't need to
// connect to returns in e.g nested closures since we'll connect those when we
// generate constraints for those closures. We also don't need to bother if
// we're generating constraints for the closure itself, since we'll connect
// the conjunction to the closure type variable itself.
if (auto *CE = dyn_cast<ClosureExpr>(DC)) {
if (isa<ReturnStmt>(stmt) && DCDepth == 0 &&
!Locator->directlyAt<ClosureExpr>()) {
SmallPtrSet<TypeVariableType *, 4> typeVars;
CS.getClosureType(CE)->getResult()->getTypeVariables(typeVars);
TypeVars.insert(typeVars.begin(), typeVars.end());
}
}
return Action::Continue(stmt);
}
namespace {
class ConstraintGenerator : public ExprVisitor<ConstraintGenerator, Type> {
ConstraintSystem &CS;
DeclContext *CurDC;
ConstraintSystemPhase CurrPhase;
/// A map from each UnresolvedMemberExpr to the respective (implicit) base
/// found during our walk.
llvm::MapVector<UnresolvedMemberExpr *, Type> UnresolvedBaseTypes;
/// A stack of pack expansions that can open pack elements.
llvm::SmallVector<PackExpansionExpr *, 1> OuterExpansions;
/// Returns false and emits the specified diagnostic if the member reference
/// base is a nil literal. Returns true otherwise.
bool isValidBaseOfMemberRef(Expr *base, Diag<> diagnostic) {
if (auto nilLiteral = dyn_cast<NilLiteralExpr>(base)) {
CS.getASTContext().Diags.diagnose(nilLiteral->getLoc(), diagnostic);
return false;
}
return true;
}
/// Retrieves a matching set of function params for an argument list.
void getMatchingParams(ArgumentList *argList,
SmallVectorImpl<AnyFunctionType::Param> &result) {
for (auto arg : *argList) {
ParameterTypeFlags flags;
auto ty = CS.getType(arg.getExpr());
if (arg.isInOut()) {
ty = ty->getInOutObjectType();
flags = flags.withInOut(true);
}
if (arg.isCompileTimeLiteral()) {
flags = flags.withCompileTimeLiteral(true);
}
result.emplace_back(ty, arg.getLabel(), flags);
}
}
/// If the provided type is a tuple, decomposes it into a matching set of
/// function params. Otherwise produces a single parameter of the type.
void decomposeTuple(Type ty,
SmallVectorImpl<AnyFunctionType::Param> &result) {
switch (ty->getKind()) {
case TypeKind::Tuple: {
auto tupleTy = cast<TupleType>(ty.getPointer());
for (auto &elt : tupleTy->getElements())
result.emplace_back(elt.getType(), elt.getName());
return;
}
default:
result.emplace_back(ty, Identifier());
}
}
/// Add constraints for a reference to a named member of the given
/// base type, and return the type of such a reference.
Type addMemberRefConstraints(Expr *expr, Expr *base, DeclNameRef name,
FunctionRefInfo functionRefInfo,
ArrayRef<ValueDecl *> outerAlternatives) {
// The base must have a member of the given name, such that accessing
// that member through the base returns a value convertible to the type
// of this expression.
auto baseTy = CS.getType(base);
if (isa<ErrorExpr>(base)) {
return CS.createTypeVariable(
CS.getConstraintLocator(expr, ConstraintLocator::Member),
TVO_CanBindToHole);
}
unsigned options = (TVO_CanBindToLValue |
TVO_CanBindToNoEscape);
if (!OuterExpansions.empty())
options |= TVO_CanBindToPack;
auto tv = CS.createTypeVariable(
CS.getConstraintLocator(expr, ConstraintLocator::Member),
options);
SmallVector<OverloadChoice, 4> outerChoices;
for (auto decl : outerAlternatives) {
outerChoices.push_back(OverloadChoice::getDecl(decl, functionRefInfo));
}
CS.addValueMemberConstraint(
baseTy, name, tv, CurDC, functionRefInfo, outerChoices,
CS.getConstraintLocator(expr, ConstraintLocator::Member));
return tv;
}
/// Add constraints for a reference to a specific member of the given
/// base type, and return the type of such a reference.
Type addMemberRefConstraints(Expr *expr, Expr *base, ValueDecl *decl,
FunctionRefInfo functionRefInfo) {
// If we're referring to an invalid declaration, fail.
if (!decl)
return nullptr;
if (decl->isInvalid())
return nullptr;
auto memberLocator =
CS.getConstraintLocator(expr, ConstraintLocator::Member);
auto tv = CS.createTypeVariable(memberLocator,
TVO_CanBindToLValue | TVO_CanBindToNoEscape);
auto choice =
OverloadChoice::getDecl(CS.getType(base), decl, functionRefInfo);
auto locator = CS.getConstraintLocator(expr, ConstraintLocator::Member);
CS.addBindOverloadConstraint(tv, choice, locator, CurDC);
return tv;
}
/// Attempt to infer a result type of a subscript reference where
/// the base type is either a stdlib Array or a Dictionary type.
/// This is a more principled version of the old performance hack
/// that used "favored" types deduced by the constraint optimizer
/// and is important to maintain pre-existing solver behavior.
Type inferCollectionSubscriptResultType(Type baseTy,
ArgumentList *argumentList) {
auto isLValueBase = false;
auto baseObjTy = baseTy;
if (baseObjTy->is<LValueType>()) {
isLValueBase = true;
baseObjTy = baseObjTy->getWithoutSpecifierType();
}
auto subscriptResultType = [&isLValueBase](Type valueTy,
bool isOptional) -> Type {
Type outputTy = isOptional ? OptionalType::get(valueTy) : valueTy;
return isLValueBase ? LValueType::get(outputTy) : outputTy;
};
if (auto *argument = argumentList->getUnlabeledUnaryExpr()) {
auto argumentTy = CS.getType(argument);
auto elementTy = baseObjTy->getArrayElementType();
if (!elementTy)
elementTy = baseObjTy->getInlineArrayElementType();
if (elementTy) {
if (auto arraySliceTy =
dyn_cast<ArraySliceType>(baseObjTy.getPointer())) {
baseObjTy = arraySliceTy->getDesugaredType();
}
if (argumentTy->isInt() || isExpr<IntegerLiteralExpr>(argument))
return subscriptResultType(elementTy, /*isOptional*/ false);
} else if (auto dictTy = CS.isDictionaryType(baseObjTy)) {
auto [keyTy, valueTy] = *dictTy;
if (keyTy->isString() &&
(isExpr<StringLiteralExpr>(argument) ||
isExpr<InterpolatedStringLiteralExpr>(argument)))
return subscriptResultType(valueTy, /*isOptional*/ true);
if (keyTy->isInt() && isExpr<IntegerLiteralExpr>(argument))
return subscriptResultType(valueTy, /*isOptional*/ true);
if (keyTy->isEqual(argumentTy))
return subscriptResultType(valueTy, /*isOptional*/ true);
}
}
return Type();
}
/// Add constraints for a subscript operation.
Type addSubscriptConstraints(
Expr *anchor, Type baseTy, ValueDecl *declOrNull, ArgumentList *argList,
ConstraintLocator *locator = nullptr,
SmallVectorImpl<TypeVariableType *> *addedTypeVars = nullptr) {
// Locators used in this expression.
if (locator == nullptr)
locator = CS.getConstraintLocator(anchor);
auto fnLocator =
CS.getConstraintLocator(locator,
ConstraintLocator::ApplyFunction);
auto memberLocator =
CS.getConstraintLocator(locator,
ConstraintLocator::SubscriptMember);
auto resultLocator =
CS.getConstraintLocator(locator,
ConstraintLocator::FunctionResult);
CS.associateArgumentList(memberLocator, argList);
Type outputTy;
// Attempt to infer the result type of a stdlib collection subscript.
if (isa<SubscriptExpr>(anchor))
outputTy = inferCollectionSubscriptResultType(baseTy, argList);
if (outputTy.isNull()) {
outputTy = CS.createTypeVariable(resultLocator,
TVO_CanBindToLValue | TVO_CanBindToNoEscape);
if (addedTypeVars)
addedTypeVars->push_back(outputTy->castTo<TypeVariableType>());
}
// FIXME: This can only happen when diagnostics successfully type-checked
// sub-expression of the subscript and mutated AST, but under normal
// circumstances subscript should never have InOutExpr as a direct child
// until type checking is complete and expression is re-written.
// Proper fix for such situation requires preventing diagnostics from
// re-writing AST after successful type checking of the sub-expressions.
if (auto inoutTy = baseTy->getAs<InOutType>()) {
baseTy = LValueType::get(inoutTy->getObjectType());
}
// Add the member constraint for a subscript declaration.
// FIXME: weak name!
auto memberTy = CS.createTypeVariable(
memberLocator, TVO_CanBindToLValue | TVO_CanBindToNoEscape);
if (addedTypeVars)
addedTypeVars->push_back(memberTy);
// FIXME: synthesizeMaterializeForSet() wants to statically dispatch to
// a known subscript here. This might be cleaner if we split off a new
// UnresolvedSubscriptExpr from SubscriptExpr.
if (auto decl = declOrNull) {
auto choice = OverloadChoice::getDecl(
baseTy, decl, FunctionRefInfo::doubleBaseNameApply());
CS.addBindOverloadConstraint(memberTy, choice, memberLocator,
CurDC);
} else {
CS.addValueMemberConstraint(baseTy, DeclNameRef::createSubscript(),
memberTy, CurDC,
FunctionRefInfo::doubleBaseNameApply(),
/*outerAlternatives=*/{}, memberLocator);
}
SmallVector<AnyFunctionType::Param, 8> params;
getMatchingParams(argList, params);
// Add the constraint that the index expression's type be convertible
// to the input type of the subscript operator.
CS.addApplicationConstraint(FunctionType::get(params, outputTy), memberTy,
/*trailingClosureMatching=*/std::nullopt,
CurDC, fnLocator);
if (CS.performanceHacksEnabled()) {
Type fixedOutputType =
CS.getFixedTypeRecursive(outputTy, /*wantRValue=*/false);
if (!fixedOutputType->isTypeVariableOrMember()) {
CS.setFavoredType(anchor, fixedOutputType.getPointer());
outputTy = fixedOutputType;
}
}
return outputTy;
}
/// Add constraints for argument resolution for `UnresolvedApply` key path
/// component kind.
Type addApplyConstraints(
Expr *anchor, Type memberTy, ArgumentList *argList,
ConstraintLocator *applyComponentLoc,
SmallVectorImpl<TypeVariableType *> *addedTypeVars = nullptr) {
// Locators used in this expression.
assert(applyComponentLoc != nullptr && "applyComponentLoc should not be null");
auto fnLocator = CS.getConstraintLocator(
applyComponentLoc, ConstraintLocator::ApplyFunction);
auto fnResultLocator = CS.getConstraintLocator(
applyComponentLoc, ConstraintLocator::FunctionResult);
CS.associateArgumentList(applyComponentLoc, argList);
Type outputTy = CS.createTypeVariable(
fnResultLocator, TVO_CanBindToLValue | TVO_CanBindToNoEscape);
if (addedTypeVars)
addedTypeVars->push_back(outputTy->castTo<TypeVariableType>());
SmallVector<AnyFunctionType::Param, 8> params;
getMatchingParams(argList, params);
SourceLoc loc =
CurDC->getAsDecl() ? CurDC->getAsDecl()->getLoc() : SourceLoc();
for (auto index : indices(params)) {
const auto &param = params[index];
CS.verifyThatArgumentIsHashable(index, param.getParameterType(),
applyComponentLoc, loc);
}
// Add the constraint that the index expression's type be convertible
// to the input type of the subscript operator.
CS.addApplicationConstraint(FunctionType::get(params, outputTy), memberTy,
/*trailingClosureMatching=*/std::nullopt,
CurDC, fnLocator);
return outputTy;
}
Type openPackElement(Type packType, ConstraintLocator *locator,
PackExpansionExpr *packElementEnvironment) {
if (!packElementEnvironment) {
return CS.createTypeVariable(locator,
TVO_CanBindToHole | TVO_CanBindToNoEscape);
}
// The type of a PackElementExpr is the opened pack element archetype
// of the pack reference.
OpenPackElementType openPackElement(CS, locator, packElementEnvironment);
return openPackElement(packType, /*packRepr*/ nullptr);
}
public:
ConstraintGenerator(ConstraintSystem &CS, DeclContext *DC)
: CS(CS), CurDC(DC ? DC : CS.DC), CurrPhase(CS.getPhase()) {
// Although constraint system is initialized in `constraint
// generation` phase, we have to set it here manually because e.g.
// result builders could generate constraints for its body
// in the middle of the solving.
CS.setPhase(ConstraintSystemPhase::ConstraintGeneration);
// Pick up the saved stack of pack expansions so we can continue
// to handle pack element references inside the closure body.
if (auto *ACE = dyn_cast<AbstractClosureExpr>(CurDC)) {
OuterExpansions = CS.getCapturedExpansions(ACE);
}
}
virtual ~ConstraintGenerator() {
CS.setPhase(CurrPhase);
}
ConstraintSystem &getConstraintSystem() const { return CS; }
void pushPackExpansionExpr(PackExpansionExpr *expr) {
OuterExpansions.push_back(expr);
SmallVector<ASTNode, 2> expandedPacks;
collectExpandedPacks(expr, expandedPacks);
for (auto pack : expandedPacks) {
if (auto *elementExpr = getAsExpr<PackElementExpr>(pack))
CS.recordPackElementExpansion(elementExpr, expr);
}
auto *patternLoc = CS.getConstraintLocator(
expr, ConstraintLocator::PackExpansionPattern);
auto patternType = CS.createTypeVariable(
patternLoc,
TVO_CanBindToPack | TVO_CanBindToNoEscape | TVO_CanBindToHole);
auto *shapeLoc =
CS.getConstraintLocator(expr, ConstraintLocator::PackShape);
auto *shapeTypeVar = CS.createTypeVariable(
shapeLoc, TVO_CanBindToPack | TVO_CanBindToHole);
auto expansionType = PackExpansionType::get(patternType, shapeTypeVar);
CS.setType(expr, expansionType);
}
/// Records a fix for an invalid AST node, and returns a potential hole
/// type variable for it.
Type recordInvalidNode(ASTNode node) {
CS.recordFix(
IgnoreInvalidASTNode::create(CS, CS.getConstraintLocator(node)));
return CS.createTypeVariable(CS.getConstraintLocator(node),
TVO_CanBindToHole);
}
virtual Type visitErrorExpr(ErrorExpr *E) {
return recordInvalidNode(E);
}
virtual Type visitCodeCompletionExpr(CodeCompletionExpr *E) {
CS.Options |= ConstraintSystemFlags::SuppressDiagnostics;
auto locator = CS.getConstraintLocator(E);
return CS.createTypeVariable(locator, TVO_CanBindToLValue |
TVO_CanBindToNoEscape |
TVO_CanBindToHole);
}
Type visitNilLiteralExpr(NilLiteralExpr *expr) {
auto literalTy = visitLiteralExpr(expr);
// Allow `nil` to be a hole so we can diagnose it via a fix
// if it turns out that there is no contextual information.
if (auto *typeVar = literalTy->getAs<TypeVariableType>())
CS.recordPotentialHole(typeVar);
return literalTy;
}
Type visitFloatLiteralExpr(FloatLiteralExpr *expr) {
auto &ctx = CS.getASTContext();
// Get the _MaxBuiltinFloatType decl, or look for it if it's not cached.
auto maxFloatTypeDecl = ctx.get_MaxBuiltinFloatTypeDecl();
if (!maxFloatTypeDecl ||
!maxFloatTypeDecl->getDeclaredInterfaceType()->is<BuiltinFloatType>()) {
ctx.Diags.diagnose(expr->getLoc(), diag::no_MaxBuiltinFloatType_found);
return nullptr;
}
return visitLiteralExpr(expr);
}
Type visitLiteralExpr(LiteralExpr *expr) {
// If the expression has already been assigned a type; just use that type.
if (expr->getType())
return expr->getType();
auto protocol = TypeChecker::getLiteralProtocol(CS.getASTContext(), expr);
if (!protocol)
return nullptr;
auto tv = CS.createTypeVariable(CS.getConstraintLocator(expr),
TVO_PrefersSubtypeBinding |
TVO_CanBindToNoEscape);
CS.addConstraint(ConstraintKind::LiteralConformsTo, tv,
protocol->getDeclaredInterfaceType(),
CS.getConstraintLocator(expr));
return tv;
}
Type
visitInterpolatedStringLiteralExpr(InterpolatedStringLiteralExpr *expr) {
// Dig out the ExpressibleByStringInterpolation protocol.
auto &ctx = CS.getASTContext();
auto interpolationProto = TypeChecker::getProtocol(
ctx, expr->getLoc(),
KnownProtocolKind::ExpressibleByStringInterpolation);
if (!interpolationProto) {
ctx.Diags.diagnose(expr->getStartLoc(),
diag::interpolation_missing_proto);
return nullptr;
}
// The type of the expression must conform to the
// ExpressibleByStringInterpolation protocol.
auto locator = CS.getConstraintLocator(expr);
auto tv = CS.createTypeVariable(locator,
TVO_PrefersSubtypeBinding |
TVO_CanBindToNoEscape);
CS.addConstraint(ConstraintKind::LiteralConformsTo, tv,
interpolationProto->getDeclaredInterfaceType(),
locator);
if (auto appendingExpr = expr->getAppendingExpr()) {
auto associatedTypeDecl = interpolationProto->getAssociatedType(
ctx.Id_StringInterpolation);
if (associatedTypeDecl == nullptr) {
ctx.Diags.diagnose(expr->getStartLoc(),
diag::interpolation_broken_proto);
return nullptr;
}
auto interpolationTV =
CS.createTypeVariable(locator, TVO_CanBindToNoEscape);
auto interpolationType =
DependentMemberType::get(tv, associatedTypeDecl);
CS.addConstraint(ConstraintKind::Equal, interpolationTV,
interpolationType, locator);
auto appendingExprType = CS.getType(appendingExpr);
auto appendingLocator = CS.getConstraintLocator(appendingExpr);
SmallVector<TypeVariableType *, 2> referencedVars;
if (auto *tap = getAsExpr<TapExpr>(appendingExpr)) {
// Collect all of the variable references that appear
// in the tap body, otherwise tap expression is going
// to get disconnected from the context.
if (auto *body = tap->getBody()) {
TypeVarRefCollector refCollector(
CS, tap->getVar()->getDeclContext(), locator);
body->walk(refCollector);
auto vars = refCollector.getTypeVars();
referencedVars.append(vars.begin(), vars.end());
}
}
// Must be Conversion; if it's Equal, then in semi-rare cases, the
// interpolation temporary variable cannot be @lvalue.
CS.addUnsolvedConstraint(Constraint::create(
CS, ConstraintKind::Conversion, appendingExprType, interpolationTV,
appendingLocator, referencedVars));
}
return tv;
}
Type visitMagicIdentifierLiteralExpr(MagicIdentifierLiteralExpr *expr) {
#ifdef SWIFT_BUILD_SWIFT_SYNTAX
auto &ctx = CS.getASTContext();
if (ctx.LangOpts.hasFeature(Feature::BuiltinMacros)) {
auto kind = MagicIdentifierLiteralExpr::getKindString(expr->getKind())
.drop_front();
auto protocol =
TypeChecker::getLiteralProtocol(CS.getASTContext(), expr);
if (!protocol)
return Type();
auto macroIdent = ctx.getIdentifier(kind);
auto macros = lookupMacros(Identifier(), macroIdent,
FunctionRefInfo::unappliedBaseName(),
MacroRole::Expression);
if (!macros.empty()) {
// Introduce an overload set for the macro reference.
auto locator = CS.getConstraintLocator(expr);
auto macroRefType = Type(CS.createTypeVariable(locator, 0));
CS.addOverloadSet(macroRefType, macros, CurDC, locator);
// FIXME: Can this be encoded in the macro definition somehow?
CS.addConstraint(ConstraintKind::LiteralConformsTo, macroRefType,
protocol->getDeclaredInterfaceType(),
CS.getConstraintLocator(expr));
return macroRefType;
}
}
// Fall through to use old implementation.
#endif
switch (expr->getKind()) {
// Magic pointer identifiers are of type UnsafeMutableRawPointer.
#define MAGIC_POINTER_IDENTIFIER(NAME, STRING) \
case MagicIdentifierLiteralExpr::NAME:
#include "swift/AST/MagicIdentifierKinds.def"
{
auto &ctx = CS.getASTContext();
if (TypeChecker::requirePointerArgumentIntrinsics(ctx, expr->getLoc()))
return nullptr;
return ctx.getUnsafeRawPointerType();
}
default:
// Others are actual literals and should be handled like any literal.
return visitLiteralExpr(expr);
}
llvm_unreachable("Unhandled MagicIdentifierLiteralExpr in switch.");
}
Type visitObjectLiteralExpr(ObjectLiteralExpr *expr) {
auto *exprLoc = CS.getConstraintLocator(expr);
CS.associateArgumentList(exprLoc, expr->getArgs());
// If the expression has already been assigned a type; just use that type.
if (expr->getType())
return expr->getType();
auto &ctx = CS.getASTContext();
auto &de = ctx.Diags;
auto protocol = TypeChecker::getLiteralProtocol(ctx, expr);
if (!protocol) {
de.diagnose(expr->getLoc(), diag::use_unknown_object_literal_protocol,
expr->getLiteralKindPlainName());
return nullptr;
}
auto witnessType = CS.createTypeVariable(
exprLoc, TVO_PrefersSubtypeBinding | TVO_CanBindToNoEscape |
TVO_CanBindToHole);
CS.addConstraint(ConstraintKind::LiteralConformsTo, witnessType,
protocol->getDeclaredInterfaceType(), exprLoc);
// The arguments are required to be argument-convertible to the
// idealized parameter type of the initializer, which generally
// simplifies the first label (e.g. "colorLiteralRed:") by stripping
// all the redundant stuff about literals (leaving e.g. "red:").
// Constraint application will quietly rewrite the type of 'args' to
// use the right labels before forming the call to the initializer.
auto constrName = TypeChecker::getObjectLiteralConstructorName(ctx, expr);
assert(constrName);
auto *constr = dyn_cast_or_null<ConstructorDecl>(
protocol->getSingleRequirement(constrName));
if (!constr) {
de.diagnose(protocol, diag::object_literal_broken_proto);
return nullptr;
}
auto *memberLoc =
CS.getConstraintLocator(expr, ConstraintLocator::ConstructorMember);
auto *fnLoc =
CS.getConstraintLocator(expr, ConstraintLocator::ApplyFunction);
auto *memberTypeLoc = CS.getConstraintLocator(
fnLoc, LocatorPathElt::ConstructorMemberType());
auto *memberType =
CS.createTypeVariable(memberTypeLoc, TVO_CanBindToNoEscape);
CS.addValueMemberConstraint(MetatypeType::get(witnessType, ctx),
DeclNameRef(constrName), memberType, CurDC,
FunctionRefInfo::doubleBaseNameApply(), {},
memberLoc);
SmallVector<AnyFunctionType::Param, 8> params;
getMatchingParams(expr->getArgs(), params);
auto resultType = CS.createTypeVariable(
CS.getConstraintLocator(expr, ConstraintLocator::FunctionResult),
TVO_CanBindToNoEscape);
CS.addApplicationConstraint(
FunctionType::get(params, resultType), memberType,
/*trailingClosureMatching=*/std::nullopt, CurDC, fnLoc);
if (constr->isFailable())
return OptionalType::get(witnessType);
return witnessType;
}
Type visitRegexLiteralExpr(RegexLiteralExpr *E) {
// Retrieve the computed Regex type from the compiler regex library.
auto ty = E->getRegexType();
if (!ty)
return recordInvalidNode(E);
return ty;
}
PackExpansionExpr *getParentPackExpansionExpr(Expr *E) const {
auto *current = E;
while (auto *parent = CS.getParentExpr(current)) {
if (auto *expansion = dyn_cast<PackExpansionExpr>(parent)) {
return expansion;
}
current = parent;
}
return nullptr;
}
Type visitDeclRefExpr(DeclRefExpr *E) {
auto locator = CS.getConstraintLocator(E);
auto invalidateReference = [&]() -> Type {
auto *hole = CS.createTypeVariable(locator, TVO_CanBindToHole);
(void)CS.recordFix(AllowRefToInvalidDecl::create(CS, locator));
CS.setType(E, hole);
return hole;
};
Type knownType;
if (auto *VD = dyn_cast<VarDecl>(E->getDecl())) {
knownType = CS.getTypeIfAvailable(VD);
if (!knownType)
knownType = VD->getTypeInContext();
if (knownType) {
// An out-of-scope type variable(s) could appear the type of
// a declaration only in diagnostic mode when invalid variable
// declaration is recursively referenced inside of a multi-statement
// closure located somewhere within its initializer e.g.:
// `let x = [<call>] { ... print(x) }`. It happens because the
// variable assumes the result type of its initializer unless
// its specified explicitly.
if (isa<ClosureExpr>(CurDC) && knownType->hasTypeVariable()) {
if (knownType.findIf([&](Type type) {
auto *typeVar = type->getAs<TypeVariableType>();
if (!typeVar || CS.getFixedType(typeVar))
return false;
return !CS.isActiveTypeVariable(typeVar);
}))
return invalidateReference();
}
// If the known type has an error, bail out.
if (knownType->hasError()) {
return invalidateReference();
}
// value packs cannot be referenced without `each` immediately
// preceding them.
if (auto *expansionType = knownType->getAs<PackExpansionType>()) {
if (!isExpr<PackElementExpr>(CS.getParentExpr(E))) {
auto packType = expansionType->getPatternType();
(void)CS.recordFix(
IgnoreMissingEachKeyword::create(CS, packType, locator));
return openPackElement(packType, locator,
getParentPackExpansionExpr(E));
}
}
if (CS.performanceHacksEnabled()) {
if (!knownType->hasPlaceholder()) {
// Set the favored type for this expression to the known type.
CS.setFavoredType(E, knownType.getPointer());
}
}
}
}
// If declaration is invalid, let's turn it into a potential hole
// and keep generating constraints.
// For code completion, we still resolve the overload and replace error
// types inside the function decl with placeholders
// (in getTypeOfReference) so we can match non-error param types.
if (!knownType && E->getDecl()->isInvalid() &&
!CS.isForCodeCompletion()) {
return invalidateReference();
}
unsigned options = (TVO_CanBindToLValue |
TVO_CanBindToNoEscape);
if (!OuterExpansions.empty())
options |= TVO_CanBindToPack;
// Create an overload choice referencing this declaration and immediately
// resolve it. This records the overload for use later.
auto tv = CS.createTypeVariable(locator, options);
auto choice =
OverloadChoice::getDecl(E->getDecl(), E->getFunctionRefInfo());
CS.addBindOverloadConstraint(tv, choice, locator, CurDC);
return tv;
}
Type visitOtherConstructorDeclRefExpr(OtherConstructorDeclRefExpr *E) {
return E->getType();
}
Type visitSuperRefExpr(SuperRefExpr *E) {
if (E->getType())
return E->getType();
// Resolve the super type of 'self'.
auto *selfDecl = E->getSelf();
DeclContext *typeContext = selfDecl->getDeclContext()->getParent();
assert(typeContext);
auto selfTy =
CS.DC->mapTypeIntoContext(typeContext->getDeclaredInterfaceType());
auto superclassTy = selfTy->getSuperclass();
if (!superclassTy)
return Type();
if (selfDecl->getInterfaceType()->is<MetatypeType>())
superclassTy = MetatypeType::get(superclassTy);
return superclassTy;
}
Type
resolveTypeReferenceInExpression(TypeRepr *repr,
TypeResolutionOptions options,
const ConstraintLocatorBuilder &locator) {
// Introduce type variables for unbound generics.
const auto genericOpener = OpenUnboundGenericType(CS, locator);
const auto placeholderHandler = HandlePlaceholderType(CS, locator);
const auto requirementOpener =
OpenGenericTypeRequirements(CS, locator,
/*preparedOverload*/ nullptr);
// Add a PackElementOf constraint for 'each T' type reprs.
PackExpansionExpr *elementEnv = nullptr;
if (!OuterExpansions.empty()) {
options |= TypeResolutionFlags::AllowPackReferences;
elementEnv = OuterExpansions.back();
}
const auto packElementOpener = OpenPackElementType(CS, locator, elementEnv);
const auto result = TypeResolution::resolveContextualType(
repr, CS.DC, options, genericOpener, placeholderHandler,
packElementOpener, requirementOpener);
// If we have an error, record a fix and produce a hole for the type.
if (result->hasError()) {
CS.recordFix(
IgnoreInvalidASTNode::create(CS, CS.getConstraintLocator(locator)));
return PlaceholderType::get(CS.getASTContext(), repr);
}
// Diagnose top-level usages of placeholder types.
if (auto *ty = dyn_cast<PlaceholderTypeRepr>(repr->getWithoutParens())) {
auto *loc = CS.getConstraintLocator(locator, {LocatorPathElt::PlaceholderType(ty)});
CS.recordFix(IgnoreInvalidPlaceholder::create(CS, loc));
}
return result;
}
Type visitTypeExpr(TypeExpr *E) {
Type type;
// If this is an implicit TypeExpr, don't validate its contents.
auto *const locator = CS.getConstraintLocator(E);
if (E->isImplicit()) {
type = CS.getInstanceType(CS.cacheType(E));
assert(type && "Implicit type expr must have type set!");
type = CS.replaceInferableTypesWithTypeVars(type, locator);
} else {
auto *repr = E->getTypeRepr();
assert(repr && "Explicit node has no type repr!");
type = resolveTypeReferenceInExpression(
repr, TypeResolverContext::InExpression, locator);
}
if (!type || type->hasError()) return Type();
return MetatypeType::get(type);
}
Type visitTypeValueExpr(TypeValueExpr *E) {
auto ty = E->getParamDecl()->getValueType();
if (ty->hasError())
return recordInvalidNode(E);
return ty;
}
Type visitDotSyntaxBaseIgnoredExpr(DotSyntaxBaseIgnoredExpr *expr) {
llvm_unreachable("Already type-checked");
}
Type visitOverloadedDeclRefExpr(OverloadedDeclRefExpr *expr) {
// For a reference to an overloaded declaration, we create a type variable
// that will be equal to different types depending on which overload
// is selected.
auto locator = CS.getConstraintLocator(expr);
auto tv = CS.createTypeVariable(locator,
TVO_CanBindToLValue | TVO_CanBindToNoEscape);
ArrayRef<ValueDecl*> decls = expr->getDecls();
SmallVector<OverloadChoice, 4> choices;
for (unsigned i = 0, n = decls.size(); i != n; ++i) {
// If the result is invalid, skip it.
// FIXME: Note this as invalid, in case we don't find a solution,
// so we don't let errors cascade further.
if (decls[i]->isInvalid())
continue;
auto choice =
OverloadChoice::getDecl(decls[i], expr->getFunctionRefInfo());
choices.push_back(choice);
}
if (choices.empty()) {
// There are no suitable overloads. Just fail.
return nullptr;
}
// Record this overload set.
CS.addOverloadSet(tv, choices, CurDC, locator);
return tv;
}
Type visitUnresolvedDeclRefExpr(UnresolvedDeclRefExpr *expr) {
// This is an error case, where we're trying to use type inference
// to help us determine which declaration the user meant to refer to.
// FIXME: Do we need to note that we're doing some kind of recovery?
return CS.createTypeVariable(CS.getConstraintLocator(expr),
TVO_CanBindToLValue |
TVO_CanBindToNoEscape);
}
Type visitMemberRefExpr(MemberRefExpr *expr) {
return addMemberRefConstraints(
expr, expr->getBase(), expr->getMember().getDecl(),
/*FIXME:*/ FunctionRefInfo::doubleBaseNameApply());
}
Type visitDynamicMemberRefExpr(DynamicMemberRefExpr *expr) {
llvm_unreachable("Already typechecked");
}
void setUnresolvedBaseType(UnresolvedMemberExpr *UME, Type ty) {
UnresolvedBaseTypes.insert({UME, ty});
}
Type getUnresolvedBaseType(UnresolvedMemberExpr *UME) {
auto result = UnresolvedBaseTypes.find(UME);
assert(result != UnresolvedBaseTypes.end());
return result->second;
}
virtual Type visitUnresolvedMemberExpr(UnresolvedMemberExpr *expr) {
auto baseLocator = CS.getConstraintLocator(
expr,
ConstraintLocator::MemberRefBase);
auto memberLocator
= CS.getConstraintLocator(expr, ConstraintLocator::UnresolvedMember);
// Since base type in this case is completely dependent on context it
// should be marked as a potential hole.
auto baseTy = CS.createTypeVariable(baseLocator, TVO_CanBindToNoEscape |
TVO_CanBindToHole);
setUnresolvedBaseType(expr, baseTy);
auto memberTy = CS.createTypeVariable(
memberLocator, TVO_CanBindToLValue | TVO_CanBindToNoEscape);
// An unresolved member expression '.member' is modeled as a value member
// constraint
//
// T0.Type[.member] == T1
//
// for fresh type variables T0 and T1, which pulls out a static
// member, i.e., an enum case or a static variable.
auto baseMetaTy = MetatypeType::get(baseTy);
CS.addUnresolvedValueMemberConstraint(baseMetaTy, expr->getName(),
memberTy, CurDC,
expr->getFunctionRefInfo(),
memberLocator);
return memberTy;
}
Type visitUnresolvedMemberChainResultExpr(
UnresolvedMemberChainResultExpr *expr) {
auto *tail = expr->getSubExpr();
auto memberTy = CS.getType(tail);
auto *base = expr->getChainBase();
assert(base == TypeChecker::getUnresolvedMemberChainBase(tail));
// The result type of the chain is represented by a new type variable.
auto locator = CS.getConstraintLocator(
expr, ConstraintLocator::UnresolvedMemberChainResult);
auto chainResultTy = CS.createTypeVariable(
locator,
TVO_CanBindToLValue | TVO_CanBindToHole | TVO_CanBindToNoEscape);
auto chainBaseTy = getUnresolvedBaseType(base);
// The result of the last element of the chain must be convertible to the
// whole chain, and the type of the whole chain must be equal to the base.
CS.addConstraint(ConstraintKind::Conversion, memberTy, chainResultTy,
locator);
CS.addConstraint(ConstraintKind::UnresolvedMemberChainBase, chainResultTy,
chainBaseTy, locator);
return chainResultTy;
}
Type visitUnresolvedDotExpr(UnresolvedDotExpr *expr) {
// UnresolvedDot applies the base to remove a single curry level from a
// member reference without using an applicable function constraint so
// we record the call argument matching here so it can be found later when
// a solution is applied to the AST.
CS.recordMatchCallArgumentResult(
CS.getConstraintLocator(expr, ConstraintLocator::ApplyArgument),
MatchCallArgumentResult::forArity(1));
// If this is Builtin.type_join*, just return any type and move
// on since we're going to discard this, and creating any type
// variables for the reference will cause problems.
auto &ctx = CS.getASTContext();
auto typeOperation = getTypeOperation(expr, ctx);
if (typeOperation != TypeOperation::None)
return ctx.getAnyExistentialType();
// If this is `Builtin.trigger_fallback_diagnostic()`, fail
// without producing any diagnostics, in order to test fallback error.
if (isTriggerFallbackDiagnosticBuiltin(expr, ctx))
return Type();
// Open a member constraint for constructor delegations on the
// subexpr type.
if (TypeChecker::getSelfForInitDelegationInConstructor(CS.DC, expr)) {
auto baseTy = CS.getType(expr->getBase())
->getWithoutSpecifierType();
// 'self' or 'super' will reference an instance, but the constructor
// is semantically a member of the metatype. This:
// self.init()
// super.init()
// is really more like:
// self = Self.init()
// self.super = Super.init()
baseTy = MetatypeType::get(baseTy, ctx);
auto memberTypeLoc = CS.getConstraintLocator(
expr, LocatorPathElt::ConstructorMemberType(
/*shortFormOrSelfDelegating*/ true));
auto methodTy =
CS.createTypeVariable(memberTypeLoc, TVO_CanBindToNoEscape);
// HACK: Bind the function's parameter list as a tuple to a type
// variable. This only exists to preserve compatibility with
// rdar://85263844, as it can affect the prioritization of bindings,
// which can affect behavior for tuple matching as tuple subtyping is
// currently a *weaker* constraint than tuple conversion.
if (!CS.getASTContext().isSwiftVersionAtLeast(6)) {
auto paramTypeVar = CS.createTypeVariable(
CS.getConstraintLocator(expr, ConstraintLocator::ApplyArgument),
TVO_CanBindToLValue | TVO_CanBindToInOut | TVO_CanBindToNoEscape |
TVO_CanBindToPack);
CS.addConstraint(ConstraintKind::BindTupleOfFunctionParams, methodTy,
paramTypeVar, CS.getConstraintLocator(expr));
}
CS.addValueMemberConstraint(
baseTy, expr->getName(), methodTy, CurDC,
expr->getFunctionRefInfo(),
/*outerAlternatives=*/{},
CS.getConstraintLocator(expr,
ConstraintLocator::ConstructorMember));
// The result of the expression is the partial application of the
// constructor to the subexpression.
return methodTy;
}
return addMemberRefConstraints(expr, expr->getBase(), expr->getName(),
expr->getFunctionRefInfo(),
expr->getOuterAlternatives());
}
/// Given a set of specialization arguments, resolve those arguments and
/// introduce them as an explicit generic arguments constraint.
///
/// \returns true if resolving any of the specialization types failed.
void addSpecializationConstraint(ConstraintLocator *locator, Type boundType,
SourceLoc lAngleLoc,
ArrayRef<TypeRepr *> specializationArgs) {
auto &ctx = CS.getASTContext();
// Resolve each type.
SmallVector<Type, 2> specializationArgTypes;
auto options =
TypeResolutionOptions(TypeResolverContext::InExpression);
ConstraintLocatorBuilder locBuilder(locator);
for (auto idx : indices(specializationArgs)) {
auto specializationArg = specializationArgs[idx];
auto argLocator =
locBuilder.withPathElement(LocatorPathElt::GenericArgument(idx));
PackExpansionExpr *elementEnv = nullptr;
if (!OuterExpansions.empty()) {
options |= TypeResolutionFlags::AllowPackReferences;
elementEnv = OuterExpansions.back();
}
auto alreadyInvalid = specializationArg->isInvalid();
auto result = TypeResolution::resolveContextualType(
specializationArg, CurDC, options,
// Introduce type variables for unbound generics.
OpenUnboundGenericType(CS, argLocator),
HandlePlaceholderType(CS, argLocator),
OpenPackElementType(CS, argLocator, elementEnv),
OpenGenericTypeRequirements(CS, locator,
/*preparedOverload*/ nullptr));
if (result->hasError()) {
if (!alreadyInvalid) {
ctx.Diags.diagnose(lAngleLoc,
diag::while_parsing_as_left_angle_bracket);
}
CS.recordFix(IgnoreInvalidASTNode::create(
CS, CS.getConstraintLocator(argLocator)));
result = PlaceholderType::get(ctx, specializationArg);
}
specializationArgTypes.push_back(result);
}
auto constraint = Constraint::create(
CS, ConstraintKind::ExplicitGenericArguments, boundType,
PackType::get(ctx, specializationArgTypes), locator);
CS.addUnsolvedConstraint(constraint);
CS.activateConstraint(constraint);
}
Type visitUnresolvedSpecializeExpr(UnresolvedSpecializeExpr *expr) {
auto baseTy = CS.getType(expr->getSubExpr());
auto *overloadLocator = CS.getConstraintLocator(expr->getSubExpr());
addSpecializationConstraint(
overloadLocator, baseTy->getMetatypeInstanceType(),
expr->getLAngleLoc(), expr->getUnresolvedParams());
return baseTy;
}
Type visitSequenceExpr(SequenceExpr *expr) {
// If a SequenceExpr survived until CSGen, then there was an upstream
// error that was already reported.
return Type();
}
Type visitArrowExpr(ArrowExpr *expr) {
// If an ArrowExpr survived until CSGen, then there was an upstream
// error that was already reported.
return Type();
}
Type visitIdentityExpr(IdentityExpr *expr) {
return CS.getType(expr->getSubExpr());
}
Type visitCopyExpr(CopyExpr *expr) {
auto valueTy = CS.createTypeVariable(CS.getConstraintLocator(expr),
TVO_PrefersSubtypeBinding |
TVO_CanBindToNoEscape);
CS.addConstraint(ConstraintKind::Equal, valueTy,
CS.getType(expr->getSubExpr()),
CS.getConstraintLocator(expr));
return valueTy;
}
Type visitConsumeExpr(ConsumeExpr *expr) {
auto valueTy = CS.createTypeVariable(CS.getConstraintLocator(expr),
TVO_PrefersSubtypeBinding |
TVO_CanBindToNoEscape);
CS.addConstraint(ConstraintKind::Equal, valueTy,
CS.getType(expr->getSubExpr()),
CS.getConstraintLocator(expr));
return valueTy;
}
Type visitAnyTryExpr(AnyTryExpr *expr) {
return CS.getType(expr->getSubExpr());
}
Type visitOptionalTryExpr(OptionalTryExpr *expr) {
auto valueTy = CS.createTypeVariable(CS.getConstraintLocator(expr),
TVO_PrefersSubtypeBinding |
TVO_CanBindToNoEscape);
Type optTy = getOptionalType(expr->getSubExpr()->getLoc(), valueTy);
if (!optTy)
return Type();
bool isDelegationToOptionalInit = false;
{
Expr *e = expr->getSubExpr();
while (true) {
e = e->getSemanticsProvidingExpr();
// Look through force-value expressions.
if (auto *FVE = dyn_cast<ForceValueExpr>(e)) {
e = FVE->getSubExpr();
continue;
}
break;
}
if (auto *CE = dyn_cast<CallExpr>(e)) {
if (auto *UDE = dyn_cast<UnresolvedDotExpr>(CE->getFn())) {
if (!CS.getType(UDE->getBase())->is<AnyMetatypeType>()) {
auto overload =
CS.findSelectedOverloadFor(CS.getConstraintLocator(
UDE, ConstraintLocator::ConstructorMember));
if (overload) {
auto *decl = overload->choice.getDeclOrNull();
if (decl && isa<ConstructorDecl>(decl) &&
decl->getDeclContext()
->getSelfNominalTypeDecl()
->isOptionalDecl())
isDelegationToOptionalInit = true;
}
}
}
}
}
// Prior to Swift 5, 'try?' always adds an additional layer of
// optionality, even if the sub-expression was already optional.
//
// NB Keep adding the additional layer in Swift 5 and on if this 'try?'
// applies to a delegation to an 'Optional' initializer, or else we won't
// discern the difference between a failure and a constructed value.
if (CS.getASTContext().LangOpts.isSwiftVersionAtLeast(5) &&
!isDelegationToOptionalInit) {
CS.addConstraint(ConstraintKind::Conversion,
CS.getType(expr->getSubExpr()), optTy,
CS.getConstraintLocator(expr));
} else {
CS.addConstraint(ConstraintKind::OptionalObject,
optTy, CS.getType(expr->getSubExpr()),
CS.getConstraintLocator(expr));
}
return optTy;
}
virtual Type visitParenExpr(ParenExpr *expr) {
// If the ParenExpr contains a pack expansion, generate a tuple
// type containing the pack expansion type.
if (CS.getType(expr->getSubExpr())->getAs<PackExpansionType>()) {
return TupleType::get({CS.getType(expr->getSubExpr())},
CS.getASTContext());
}
if (CS.performanceHacksEnabled()) {
if (auto favoredTy = CS.getFavoredType(expr->getSubExpr())) {
CS.setFavoredType(expr, favoredTy);
}
}
return CS.getType(expr->getSubExpr());
}
Type visitTupleExpr(TupleExpr *expr) {
// The type of a tuple expression is simply a tuple of the types of
// its subexpressions.
SmallVector<TupleTypeElt, 4> elements;
elements.reserve(expr->getNumElements());
for (unsigned i = 0, n = expr->getNumElements(); i != n; ++i) {
elements.emplace_back(CS.getType(expr->getElement(i)),
expr->getElementName(i));
}
return TupleType::get(elements, CS.getASTContext());
}
Type visitSubscriptExpr(SubscriptExpr *expr) {
ValueDecl *decl = nullptr;
if (expr->hasDecl()) {
decl = expr->getDecl().getDecl();
if (decl->isInvalid())
return Type();
}
auto *base = expr->getBase();
if (!isValidBaseOfMemberRef(base, diag::cannot_subscript_nil_literal))
return nullptr;
return addSubscriptConstraints(expr, CS.getType(base), decl,
expr->getArgs());
}
Type visitArrayExpr(ArrayExpr *expr) {
auto &ctx = CS.getASTContext();
// An array expression can be of a type T that conforms to the
// ExpressibleByArrayLiteral protocol.
auto *arrayProto = TypeChecker::getProtocol(
ctx, expr->getLoc(),
KnownProtocolKind::ExpressibleByArrayLiteral);
if (!arrayProto) {
return Type();
}
// Assume that ExpressibleByArrayLiteral contains a single associated type.
auto *elementAssocTy = arrayProto->getAssociatedTypeMembers()[0];
if (!elementAssocTy)
return Type();
auto locator = CS.getConstraintLocator(expr);
auto contextualType = CS.getContextualType(expr, /*forConstraint=*/false);
auto contextualPurpose = CS.getContextualTypePurpose(expr);
auto joinElementTypes = [&](std::optional<Type> elementType) {
const auto elements = expr->getElements();
unsigned index = 0;
using Iterator = decltype(elements)::iterator;
CS.addJoinConstraint<Iterator>(
locator, elements.begin(), elements.end(), elementType,
[&](const auto it) {
auto *locator = CS.getConstraintLocator(
expr, LocatorPathElt::TupleElement(index++));
return std::make_pair(CS.getType(*it), locator);
});
};
// If a contextual type exists for this expression, apply it directly.
if (contextualType &&
(contextualType->getArrayElementType() ||
contextualType->getInlineArrayElementType())) {
// Now that we know we're actually going to use the type, get the
// version for use in a constraint.
contextualType = CS.getContextualType(expr, /*forConstraint=*/true);
// FIXME: This is the wrong place to be opening the opaque type.
contextualType = CS.openOpaqueType(
contextualType, contextualPurpose, locator, /*ownerDecl=*/nullptr);
Type eltType;
if (contextualType->isArray())
eltType = contextualType->getArrayElementType();
if (contextualType->isInlineArray() || contextualType->is_InlineArray())
eltType = contextualType->getInlineArrayElementType();
CS.addConstraint(ConstraintKind::LiteralConformsTo, contextualType,
arrayProto->getDeclaredInterfaceType(),
locator);
joinElementTypes(eltType);
return contextualType;
}
// Produce a specialized diagnostic if this is an attempt to initialize
// or convert an array literal to a dictionary e.g.
// `let _: [String: Int] = ["A", 0]`
auto isDictionaryContextualType = [&](Type contextualType) -> bool {
if (!contextualType)
return false;
auto type = contextualType->lookThroughAllOptionalTypes();
if (lookupConformance(type, arrayProto))
return false;
if (auto *proto = ctx.getProtocol(KnownProtocolKind::ExpressibleByDictionaryLiteral))
if (lookupConformance(type, proto))
return true;
return false;
};
if (isDictionaryContextualType(contextualType)) {
auto &DE = CS.getASTContext().Diags;
auto numElements = expr->getNumElements();
// Empty and single element array literals with dictionary contextual
// types are fixed during solving, so continue as normal in those
// cases.
if (numElements > 1) {
bool isIniting =
CS.getContextualTypePurpose(expr) == CTP_Initialization;
DE.diagnose(expr->getStartLoc(), diag::should_use_dictionary_literal,
contextualType->lookThroughAllOptionalTypes(), isIniting);
auto diagnostic =
DE.diagnose(expr->getStartLoc(), diag::meant_dictionary_lit);
// If there is an even number of elements in the array, let's produce
// a fix-it which suggests to replace "," with ":" to form a dictionary
// literal.
if ((numElements & 1) == 0) {
const auto commaLocs = expr->getCommaLocs();
if (commaLocs.size() == numElements - 1) {
for (unsigned i = 0, e = numElements / 2; i != e; ++i)
diagnostic.fixItReplace(commaLocs[i * 2], ":");
}
}
return nullptr;
}
}
auto arrayTy = CS.createTypeVariable(locator,
TVO_PrefersSubtypeBinding |
TVO_CanBindToNoEscape);
// The array must be an array literal type.
CS.addConstraint(ConstraintKind::LiteralConformsTo, arrayTy,
arrayProto->getDeclaredInterfaceType(),
locator);
// Its subexpression should be convertible to a tuple (T.Element...).
Type arrayElementTy = DependentMemberType::get(arrayTy, elementAssocTy);
// Introduce conversions from each element to the element type of the
// array.
joinElementTypes(arrayElementTy);
// The array element type defaults to 'Any'.
CS.addConstraint(ConstraintKind::Defaultable, arrayElementTy,
ctx.getAnyExistentialType(), locator);
return arrayTy;
}
static bool isMergeableValueKind(Expr *expr) {
return isa<StringLiteralExpr>(expr) || isa<IntegerLiteralExpr>(expr) ||
isa<FloatLiteralExpr>(expr);
}
Type visitDictionaryExpr(DictionaryExpr *expr) {
ASTContext &C = CS.getASTContext();
// A dictionary expression can be of a type T that conforms to the
// ExpressibleByDictionaryLiteral protocol.
// FIXME: This isn't actually used for anything at the moment.
ProtocolDecl *dictionaryProto = TypeChecker::getProtocol(
C, expr->getLoc(), KnownProtocolKind::ExpressibleByDictionaryLiteral);
if (!dictionaryProto) {
return Type();
}
// FIXME: Protect against broken standard library.
auto keyAssocTy = dictionaryProto->getAssociatedType(C.Id_Key);
auto valueAssocTy = dictionaryProto->getAssociatedType(C.Id_Value);
auto locator = CS.getConstraintLocator(expr);
auto contextualType = CS.getContextualType(expr, /*forConstraint=*/false);
auto contextualPurpose = CS.getContextualTypePurpose(expr);
// If a contextual type exists for this expression and is a dictionary
// type, apply it directly.
if (contextualType && ConstraintSystem::isDictionaryType(contextualType)) {
// Now that we know we're actually going to use the type, get the
// version for use in a constraint.
contextualType = CS.getContextualType(expr, /*forConstraint=*/true);
// FIXME: This is the wrong place to be opening the opaque type.
auto openedType =
CS.openOpaqueType(contextualType, contextualPurpose, locator,
/*ownerDecl=*/nullptr);
auto dictionaryKeyValue =
ConstraintSystem::isDictionaryType(openedType);
Type contextualDictionaryKeyType;
Type contextualDictionaryValueType;
std::tie(contextualDictionaryKeyType,
contextualDictionaryValueType) = *dictionaryKeyValue;
// Form an explicit tuple type from the contextual type's key and value types.
TupleTypeElt tupleElts[2] = { TupleTypeElt(contextualDictionaryKeyType),
TupleTypeElt(contextualDictionaryValueType) };
Type contextualDictionaryElementType = TupleType::get(tupleElts, C);
CS.addConstraint(ConstraintKind::LiteralConformsTo, openedType,
dictionaryProto->getDeclaredInterfaceType(), locator);
unsigned index = 0;
for (auto element : expr->getElements()) {
CS.addConstraint(ConstraintKind::Conversion,
CS.getType(element),
contextualDictionaryElementType,
CS.getConstraintLocator(
expr, LocatorPathElt::TupleElement(index++)));
}
return openedType;
}
auto dictionaryTy = CS.createTypeVariable(locator,
TVO_PrefersSubtypeBinding |
TVO_CanBindToNoEscape);
// The dictionary must be a dictionary literal type.
CS.addConstraint(ConstraintKind::LiteralConformsTo, dictionaryTy,
dictionaryProto->getDeclaredInterfaceType(),
locator);
// Its subexpression should be convertible to a tuple ((T.Key,T.Value)...).
ConstraintLocatorBuilder locatorBuilder(locator);
auto dictionaryKeyTy = DependentMemberType::get(dictionaryTy,
keyAssocTy);
auto dictionaryValueTy = DependentMemberType::get(dictionaryTy,
valueAssocTy);
TupleTypeElt tupleElts[2] = { TupleTypeElt(dictionaryKeyTy),
TupleTypeElt(dictionaryValueTy) };
Type elementTy = TupleType::get(tupleElts, C);
// Keep track of which elements have been "merged". This way, we won't create
// needless conversion constraints for elements whose equivalence classes have
// been merged.
llvm::DenseSet<Expr *> mergedElements;
// If no contextual type is present, Merge equivalence classes of key
// and value types as necessary.
if (!CS.getContextualType(expr, /*forConstraint=*/false)) {
for (auto element1 : expr->getElements()) {
for (auto element2 : expr->getElements()) {
if (element1 == element2)
continue;
auto tty1 = CS.getType(element1)->getAs<TupleType>();
auto tty2 = CS.getType(element2)->getAs<TupleType>();
if (tty1 && tty2) {
auto mergedKey = false;
auto mergedValue = false;
auto keyTyvar1 = tty1->getElementTypes()[0]->
getAs<TypeVariableType>();
auto keyTyvar2 = tty2->getElementTypes()[0]->
getAs<TypeVariableType>();
auto keyExpr1 = cast<TupleExpr>(element1)->getElements()[0];
auto keyExpr2 = cast<TupleExpr>(element2)->getElements()[0];
if (keyExpr1->getKind() == keyExpr2->getKind() &&
isMergeableValueKind(keyExpr1)) {
mergedKey = mergeRepresentativeEquivalenceClasses(CS,
keyTyvar1, keyTyvar2);
}
auto valueTyvar1 = tty1->getElementTypes()[1]->
getAs<TypeVariableType>();
auto valueTyvar2 = tty2->getElementTypes()[1]->
getAs<TypeVariableType>();
auto elemExpr1 = cast<TupleExpr>(element1)->getElements()[1];
auto elemExpr2 = cast<TupleExpr>(element2)->getElements()[1];
if (elemExpr1->getKind() == elemExpr2->getKind() &&
isMergeableValueKind(elemExpr1)) {
mergedValue = mergeRepresentativeEquivalenceClasses(CS,
valueTyvar1, valueTyvar2);
}
if (mergedKey && mergedValue)
mergedElements.insert(element2);
}
}
}
}
// Introduce conversions from each element to the element type of the
// dictionary. (If the equivalence class of an element has already been
// merged with a previous one, skip it.)
unsigned index = 0;
for (auto element : expr->getElements()) {
if (!mergedElements.count(element))
CS.addConstraint(ConstraintKind::Conversion,
CS.getType(element),
elementTy,
CS.getConstraintLocator(
expr, LocatorPathElt::TupleElement(index++)));
}
// The dictionary key type defaults to 'AnyHashable'.
auto &ctx = CS.getASTContext();
if (dictionaryKeyTy->isTypeVariableOrMember() &&
ctx.getAnyHashableDecl()) {
auto anyHashable = ctx.getAnyHashableDecl();
CS.addConstraint(ConstraintKind::Defaultable, dictionaryKeyTy,
anyHashable->getDeclaredInterfaceType(), locator);
}
// The dictionary value type defaults to 'Any'.
if (dictionaryValueTy->isTypeVariableOrMember()) {
CS.addConstraint(ConstraintKind::Defaultable, dictionaryValueTy,
ctx.getAnyExistentialType(), locator);
}
return dictionaryTy;
}
Type visitDynamicSubscriptExpr(DynamicSubscriptExpr *expr) {
return addSubscriptConstraints(expr, CS.getType(expr->getBase()),
/*decl*/ nullptr, expr->getArgs());
}
Type visitTupleElementExpr(TupleElementExpr *expr) {
ASTContext &context = CS.getASTContext();
DeclNameRef name(
context.getIdentifier(llvm::utostr(expr->getFieldNumber())));
return addMemberRefConstraints(expr, expr->getBase(), name,
FunctionRefInfo::unappliedBaseName(),
/*outerAlternatives=*/{});
}
/// If \p allowResultBindToHole is \c true, we always allow the closure's
/// result type to bind to a hole, otherwise the result type may only bind
/// to a hole if the closure does not participate in type inference. Setting
/// \p allowResultBindToHole to \c true is useful when ignoring a closure
/// argument in a function call after the code completion token and thus
/// wanting to ignore the closure's type.
FunctionType *inferClosureType(ClosureExpr *closure,
bool allowResultBindToHole = false) {
SmallVector<AnyFunctionType::Param, 4> closureParams;
if (auto *paramList = closure->getParameters()) {
for (unsigned i = 0, n = paramList->size(); i != n; ++i) {
auto *param = paramList->get(i);
auto *paramLoc =
CS.getConstraintLocator(closure, LocatorPathElt::TupleElement(i));
// If one of the parameters represents a destructured tuple
// e.g. `{ (x: Int, (y: Int, z: Int)) in ... }` let's fail
// inference here and not attempt to solve the system because:
//
// a. Destructuring has already been diagnosed by the parser;
// b. Body of the closure would have error expressions for
// each incorrect parameter reference and solver wouldn't
// be able to produce any viable solutions.
if (param->isDestructured())
return nullptr;
Type externalType;
if (param->getTypeRepr()) {
auto declaredTy = param->getTypeInContext();
// If closure parameter couldn't be resolved, let's record
// a fix to make sure that type resolution diagnosed the
// problem and replace it with a placeholder, so that solver
// can make forward progress (especially important for result
// builders).
if (declaredTy->hasError()) {
CS.recordFix(AllowRefToInvalidDecl::create(
CS, CS.getConstraintLocator(param)));
declaredTy = PlaceholderType::get(CS.getASTContext(), param);
}
externalType = CS.replaceInferableTypesWithTypeVars(declaredTy,
paramLoc);
} else {
// Let's allow parameters which haven't been explicitly typed
// to become holes by default, this helps in situations like
// `foo { a in }` where `foo` doesn't exist.
externalType = CS.createTypeVariable(
paramLoc,
TVO_CanBindToInOut | TVO_CanBindToNoEscape | TVO_CanBindToHole);
}
closureParams.push_back(param->toFunctionParam(externalType));
}
checkVariadicParameters(paramList, closure);
}
auto extInfo = CS.closureEffects(closure);
auto resultLocator =
CS.getConstraintLocator(closure, ConstraintLocator::ClosureResult);
auto thrownErrorLocator =
CS.getConstraintLocator(closure, ConstraintLocator::ClosureThrownError);
// Determine the thrown error type, when appropriate.
Type thrownErrorTy = [&] {
// Explicitly-specified thrown type.
if (closure->getExplicitThrownTypeRepr()) {
if (Type explicitType = closure->getExplicitThrownType()) {
// The thrown type may have errors, open as placeholders if needed.
return CS.replaceInferableTypesWithTypeVars(explicitType,
thrownErrorLocator);
}
}
// Explicitly-specified 'throws' without a type is untyped throws.
// Use a NULL return here so that the inferred type is written with
// `throws` instead of `throws(any Error)`, although the two are
// semantically equivalent.
if (closure->getThrowsLoc().isValid())
return Type();
// Thrown type inferred from context.
if (auto contextualType = CS.getContextualType(
closure, /*forConstraint=*/false)) {
if (auto fnType = contextualType->getAs<AnyFunctionType>()) {
if (Type thrownErrorTy = fnType->getThrownError())
return thrownErrorTy;
}
}
// We do not try to infer a thrown error type if one isn't immediately
// available.
return Type();
}();
if (thrownErrorTy) {
// Record the thrown error type in the extended info for the function
// type of the closure.
extInfo = extInfo.withThrows(true, thrownErrorTy);
// Ensure that the thrown error type conforms to Error.
if (auto errorProto =
CS.getASTContext().getProtocol(KnownProtocolKind::Error)) {
CS.addConstraint(
ConstraintKind::ConformsTo, thrownErrorTy,
errorProto->getDeclaredInterfaceType(), thrownErrorLocator);
}
}
// Closure expressions always have function type. In cases where a
// parameter or return type is omitted, a fresh type variable is used to
// stand in for that parameter or return type, allowing it to be inferred
// from context.
Type resultTy = [&] {
if (closure->hasExplicitResultType()) {
if (auto declaredTy = closure->getExplicitResultType()) {
return declaredTy;
}
auto options =
TypeResolutionOptions(TypeResolverContext::InExpression);
options.setContext(TypeResolverContext::ClosureExpr);
const auto resolvedTy = resolveTypeReferenceInExpression(
closure->getExplicitResultTypeRepr(), options, resultLocator);
if (resolvedTy)
return resolvedTy;
}
// Because we are only pulling out the result type from the contextual
// type, we avoid prematurely converting any inferrable types by setting
// forConstraint=false. Later on in inferClosureType we call
// replaceInferableTypesWithTypeVars before returning to ensure we don't
// introduce any placeholders into the constraint system.
if (auto contextualType =
CS.getContextualType(closure, /*forConstraint=*/false)) {
if (auto fnType = contextualType->getAs<FunctionType>())
return fnType->getResult();
}
// If no return type was specified, create a fresh type
// variable for it and mark it as possible hole.
//
// If this is a multi-statement closure, let's mark result
// as potential hole right away.
return Type(CS.createTypeVariable(
resultLocator, allowResultBindToHole ? TVO_CanBindToHole : 0));
}();
// Determine the isolation of the closure.
auto isolation = [&] {
// Priority goes to an explicit isolated parameter.
if (hasIsolatedParameter(closureParams))
return FunctionTypeIsolation::forParameter();
// Honor an explicit global actor. This is suppressed if the
// closure is async (but should it be?).
if (!extInfo.isAsync()) {
if (auto actorType = getExplicitGlobalActor(closure))
return FunctionTypeIsolation::forGlobalActor(actorType);
}
if (closure->getAttrs().hasAttribute<ConcurrentAttr>()) {
return FunctionTypeIsolation::forNonIsolated();
}
return FunctionTypeIsolation::forNonIsolated();
}();
extInfo = extInfo.withIsolation(isolation);
if (isolation.isGlobalActor() &&
CS.getASTContext().LangOpts.hasFeature(Feature::GlobalActorIsolatedTypesUsability)) {
extInfo = extInfo.withSendable();
}
auto *fnTy = FunctionType::get(closureParams, resultTy, extInfo);
return CS.replaceInferableTypesWithTypeVars(
fnTy, CS.getConstraintLocator(closure))->castTo<FunctionType>();
}
/// Produces a type for the given pattern, filling in any missing
/// type information with fresh type variables.
///
/// \param pattern The pattern.
///
/// \param locator The locator to use for generated constraints and
/// type variables.
///
/// \param bindPatternVarsOneWay When true, generate fresh type variables
/// for the types of each variable declared within the pattern, along
/// with a one-way constraint binding that to the type to which the
/// variable will be ascribed or inferred.
Type getTypeForPattern(
Pattern *pattern, ConstraintLocatorBuilder locator,
bool bindPatternVarsOneWay,
PatternBindingDecl *patternBinding = nullptr,
unsigned patternBindingIndex = 0) {
assert(pattern);
// Local function that must be called for each "return" throughout this
// function, to set the type of the pattern.
auto setType = [&](Type type) {
CS.setType(pattern, type);
return type;
};
switch (pattern->getKind()) {
case PatternKind::Paren: {
auto *paren = cast<ParenPattern>(pattern);
auto *subPattern = paren->getSubPattern();
auto underlyingType = getTypeForPattern(
subPattern,
locator.withPathElement(LocatorPathElt::PatternMatch(subPattern)),
bindPatternVarsOneWay);
return setType(underlyingType);
}
case PatternKind::Binding: {
auto *subPattern = cast<BindingPattern>(pattern)->getSubPattern();
auto type = getTypeForPattern(subPattern, locator,
bindPatternVarsOneWay);
// Var doesn't affect the type.
return setType(type);
}
case PatternKind::Any: {
Type type;
// If this is a situation like `[let] _ = <expr>`, return
// initializer expression.
auto getInitializerExpr = [&locator]() -> Expr * {
auto last = locator.last();
if (!last)
return nullptr;
auto contextualTy = last->getAs<LocatorPathElt::ContextualType>();
return (contextualTy && contextualTy->isFor(CTP_Initialization))
? locator.trySimplifyToExpr()
: nullptr;
};
auto matchLoc =
locator.withPathElement(LocatorPathElt::PatternMatch(pattern));
// Always prefer a contextual type when it's available.
if (auto *initializer = getInitializerExpr()) {
// For initialization always assume a type of initializer.
type = CS.getType(initializer)->getRValueType();
} else {
type = CS.createTypeVariable(
CS.getConstraintLocator(matchLoc,
LocatorPathElt::AnyPatternDecl()),
TVO_CanBindToNoEscape | TVO_CanBindToHole);
}
return setType(type);
}
case PatternKind::Named: {
auto var = cast<NamedPattern>(pattern)->getDecl();
Type varType;
// Determine whether optionality will be required.
auto ROK = ReferenceOwnership::Strong;
if (auto *OA = var->getAttrs().getAttribute<ReferenceOwnershipAttr>())
ROK = OA->get();
auto optionality = optionalityOf(ROK);
// If we have a type from an initializer expression, and that
// expression does not produce an InOut type, use it. This
// will avoid exponential typecheck behavior in the case of
// tuples, nested arrays, and dictionary literals.
//
// FIXME: This should be handled in the solver, not here.
//
// Otherwise, create a new type variable.
if (var->getParentPatternBinding() &&
!var->hasAttachedPropertyWrapper() &&
optionality != ReferenceOwnershipOptionality::Required) {
if (auto boundExpr = locator.trySimplifyToExpr()) {
if (!boundExpr->isSemanticallyInOutExpr()) {
varType = CS.getType(boundExpr)->getRValueType();
}
}
}
auto matchLoc =
locator.withPathElement(LocatorPathElt::PatternMatch(pattern));
if (!varType) {
varType = CS.createTypeVariable(
CS.getConstraintLocator(matchLoc,
LocatorPathElt::NamedPatternDecl()),
TVO_CanBindToNoEscape | TVO_CanBindToHole);
// If this is either a `weak` declaration or capture e.g.
// `weak var ...` or `[weak self]`. Let's wrap type variable
// into an optional.
if (optionality == ReferenceOwnershipOptionality::Required)
varType = TypeChecker::getOptionalType(var->getLoc(), varType);
}
auto makeTypeLocatableIfPossible = [&var](Type type) -> Type {
if (auto loc = var->getLoc()) {
return LocatableType::get(loc, type);
}
return type;
};
auto useLocatableTypes = [&]() -> bool {
if (!CS.inSalvageMode())
return false;
return var->isImplicit() &&
var->getNameStr().starts_with("$__builder");
};
// When we are supposed to bind pattern variables, create a fresh
// type variable and a one-way constraint to assign it to either the
// deduced type or the externally-imposed type.
Type oneWayVarType;
if (bindPatternVarsOneWay) {
oneWayVarType = CS.createTypeVariable(
CS.getConstraintLocator(locator), TVO_CanBindToNoEscape);
// If there is externally-imposed type, and the variable
// is marked as `weak`, let's fallthrough and allow the
// `one-way` constraint to be fixed in diagnostic mode.
//
// That would make sure that type of this variable is
// recorded in the constraint system, which would then
// be used instead of `getVarType` upon discovering a
// reference to this variable in subsequent expression(s).
//
// If we let constraint generation fail here, it would trigger
// interface type request via `var->getType()` that would
// attempt to validate `weak` attribute, and produce a
// diagnostic in the middle of the solver path.
//
// FIXME: getVarType() is now gone. Is the above still
// relevant?
CS.addConstraint(ConstraintKind::OneWayEqual, oneWayVarType,
varType, locator);
if (useLocatableTypes())
oneWayVarType = makeTypeLocatableIfPossible(oneWayVarType);
}
// Ascribe a type to the declaration so it's always available to
// constraint system.
if (oneWayVarType) {
CS.setType(var, oneWayVarType);
} else {
// Otherwise, let's use the type of the pattern. The type
// of the declaration has to be r-value, so let's add an
// equality constraint if pattern type has any type variables
// that are allowed to be l-value.
bool foundLValueVars = false;
// Note that it wouldn't be always correct to allocate a single type
// variable, that disallows l-value types, to use as a declaration
// type because equality constraint would drop TVO_CanBindToLValue
// from the right-hand side (which is not the case for `OneWayEqual`)
// e.g.:
//
// struct S { var x, y: Int }
//
// func test(s: S) {
// let (x, y) = (s.x, s.y)
// }
//
// Single type variable approach results in the following constraint:
// `$T_x_y = ($T_s_x, $T_s_y)` where both `$T_s_x` and `$T_s_y` have
// to allow l-value, but `$T_x_y` does not. Early simplification of `=`
// constraint (due to right-hand side being a "concrete" tuple type)
// would drop l-value option from `$T_s_x` and `$T_s_y` which leads to
// a failure during member lookup because `x` and `y` are both
// `@lvalue Int`. To avoid that, declaration type would mimic pattern
// type with all l-value options stripped, so the equality constraint
// becomes `($T_x, $_T_y) = ($T_s_x, $T_s_y)` which doesn't result in
// stripping of l-value flag from the right-hand side since
// simplification can only happen when either side is resolved.
auto declTy = varType.transformRec([&](Type type) -> std::optional<Type> {
if (auto *typeVar = type->getAs<TypeVariableType>()) {
if (typeVar->getImpl().canBindToLValue()) {
foundLValueVars = true;
// Drop l-value from the options but preserve the rest.
auto options = typeVar->getImpl().getRawOptions();
options &= ~TVO_CanBindToLValue;
return Type(CS.createTypeVariable(typeVar->getImpl().getLocator(),
options));
}
}
return std::nullopt;
});
// If pattern types allows l-value types, let's create an
// equality constraint between r-value only declaration type
// and l-value pattern type that would take care of looking
// through l-values when necessary.
if (foundLValueVars) {
CS.addConstraint(ConstraintKind::Equal, declTy, varType,
CS.getConstraintLocator(locator));
}
if (useLocatableTypes())
declTy = makeTypeLocatableIfPossible(declTy);
CS.setType(var, declTy);
}
return setType(varType);
}
case PatternKind::Typed: {
// FIXME: Need a better locator for a pattern as a base.
// Compute the type ascribed to the pattern.
auto contextualPattern = patternBinding
? ContextualPattern::forPatternBindingDecl(
patternBinding, patternBindingIndex)
: ContextualPattern::forRawPattern(pattern, CurDC);
Type type = TypeChecker::typeCheckPattern(contextualPattern);
// Look through reference storage types.
type = type->getReferenceStorageReferent();
Type replacedType = CS.replaceInferableTypesWithTypeVars(type, locator);
Type openedType =
CS.openOpaqueType(replacedType, CTP_Initialization, locator,
patternBinding);
assert(openedType);
auto *subPattern = cast<TypedPattern>(pattern)->getSubPattern();
// Determine the subpattern type. It will be convertible to the
// ascribed type.
Type subPatternType = getTypeForPattern(
subPattern,
locator.withPathElement(LocatorPathElt::PatternMatch(subPattern)),
bindPatternVarsOneWay);
// NOTE: The order here is important! Pattern matching equality is
// not symmetric (we need to fix that either by using a different
// constraint, or actually making it symmetric).
CS.addConstraint(
ConstraintKind::Equal, openedType, subPatternType,
locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));
// FIXME [OPAQUE SUPPORT]: the distinction between where we want opaque
// types in opened vs. un-unopened form is *very* tricky. The pattern
// ultimately needs the un-opened type and it gets this from the set
// type of the expression.
CS.setType(pattern, replacedType);
return openedType;
}
case PatternKind::Tuple: {
auto tuplePat = cast<TuplePattern>(pattern);
SmallVector<TupleTypeElt, 4> tupleTypeElts;
tupleTypeElts.reserve(tuplePat->getNumElements());
for (unsigned i = 0, e = tuplePat->getNumElements(); i != e; ++i) {
auto &tupleElt = tuplePat->getElement(i);
auto *eltPattern = tupleElt.getPattern();
Type eltTy = getTypeForPattern(
eltPattern,
locator.withPathElement(LocatorPathElt::PatternMatch(eltPattern)),
bindPatternVarsOneWay);
tupleTypeElts.push_back(TupleTypeElt(eltTy, tupleElt.getLabel()));
}
return setType(TupleType::get(tupleTypeElts, CS.getASTContext()));
}
case PatternKind::OptionalSome: {
auto *subPattern = cast<OptionalSomePattern>(pattern)->getSubPattern();
// The subpattern must have optional type.
Type subPatternType = getTypeForPattern(
subPattern,
locator.withPathElement(LocatorPathElt::PatternMatch(subPattern)),
bindPatternVarsOneWay);
return setType(OptionalType::get(subPatternType));
}
case PatternKind::Is: {
auto isPattern = cast<IsPattern>(pattern);
const Type castType = resolveTypeReferenceInExpression(
isPattern->getCastTypeRepr(), TypeResolverContext::InExpression,
locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));
// Allow `is` pattern to infer type from context which is then going
// to be propaged down to its sub-pattern via conversion. This enables
// correct handling of patterns like `_ as Foo` where `_` would
// get a type of `Foo` but `is` pattern enclosing it could still be
// inferred from enclosing context.
auto isType =
CS.createTypeVariable(CS.getConstraintLocator(pattern),
TVO_CanBindToNoEscape | TVO_CanBindToHole);
// Make sure we can cast from the subpattern type to the type we're
// checking; if it's impossible, fail.
CS.addConstraint(
ConstraintKind::CheckedCast, isType, castType,
locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));
if (auto *subPattern = isPattern->getSubPattern()) {
auto subPatternType = getTypeForPattern(
subPattern,
locator.withPathElement(LocatorPathElt::PatternMatch(subPattern)),
bindPatternVarsOneWay);
// NOTE: The order here is important! Pattern matching equality is
// not symmetric (we need to fix that either by using a different
// constraint, or actually making it symmetric).
CS.addConstraint(
ConstraintKind::Equal, castType, subPatternType,
locator.withPathElement(LocatorPathElt::PatternMatch(pattern)));
}
return setType(isType);
}
case PatternKind::Bool:
return setType(CS.getASTContext().getBoolType());
case PatternKind::EnumElement: {
auto enumPattern = cast<EnumElementPattern>(pattern);
// Create a type variable to represent the pattern.
Type patternType =
CS.createTypeVariable(CS.getConstraintLocator(locator),
TVO_CanBindToNoEscape);
// Form the member constraint for a reference to a member of this
// type.
Type baseType;
Type memberType = CS.createTypeVariable(
CS.getConstraintLocator(locator),
TVO_CanBindToLValue | TVO_CanBindToNoEscape);
// Tuple splat is still allowed for patterns (with a warning in Swift 5)
// so we need to set a non-compound reference to make sure that e.g.
// `case test(x: Int, y: Int)` gets the labels preserved when matched
// with `case let .test(tuple)`.
auto functionRefInfo = FunctionRefInfo::unappliedBaseName();
if (enumPattern->hasSubPattern())
functionRefInfo = functionRefInfo.addingApplicationLevel();
// If sub-pattern is a tuple we'd need to mark reference as compound,
// that would make sure that the labels are dropped in cases
// when `case` has a single tuple argument (tuple explosion) or multiple
// arguments (tuple-to-tuple conversion).
// FIXME: We ought to be preserving labels and matching in the solver.
if (dyn_cast_or_null<TuplePattern>(enumPattern->getSubPattern()))
functionRefInfo = FunctionRefInfo::singleCompoundNameApply();
auto patternLocator =
locator.withPathElement(LocatorPathElt::PatternMatch(pattern));
if (enumPattern->getParentType() || enumPattern->getParentTypeRepr()) {
// Resolve the parent type.
const auto parentType = [&] {
auto *const patternMatchLoc = CS.getConstraintLocator(
locator, {LocatorPathElt::PatternMatch(pattern),
ConstraintLocator::ParentType});
// FIXME: Sometimes the parent type is realized eagerly in
// ResolvePattern::visitUnresolvedDotExpr, so we have to open it
// ex post facto. Remove this once we learn how to resolve patterns
// while generating constraints to keep the opening of generic types
// contained within the type resolver.
if (const auto preresolvedTy = enumPattern->getParentType()) {
const auto openedTy =
CS.replaceInferableTypesWithTypeVars(preresolvedTy,
patternMatchLoc);
assert(openedTy);
return openedTy;
}
return resolveTypeReferenceInExpression(
enumPattern->getParentTypeRepr(),
TypeResolverContext::InExpression, patternMatchLoc);
}();
// Perform member lookup into the parent's metatype.
Type parentMetaType = MetatypeType::get(parentType);
CS.addValueMemberConstraint(parentMetaType, enumPattern->getName(),
memberType, CurDC, functionRefInfo, {},
patternLocator);
// Parent type needs to be convertible to the pattern type; this
// accounts for cases where the pattern type is existential.
CS.addConstraint(
ConstraintKind::Conversion, parentType, patternType,
patternLocator.withPathElement(
ConstraintLocator::EnumPatternImplicitCastMatch));
baseType = parentType;
} else {
// Use the pattern type for member lookup.
CS.addUnresolvedValueMemberConstraint(
MetatypeType::get(patternType), enumPattern->getName(),
memberType, CurDC, functionRefInfo, patternLocator);
baseType = patternType;
}
if (auto subPattern = enumPattern->getSubPattern()) {
// When there is a subpattern, the member will have function type,
// and we're matching the type of that subpattern to the parameter
// types.
Type subPatternType = getTypeForPattern(
subPattern,
locator.withPathElement(LocatorPathElt::PatternMatch(subPattern)),
bindPatternVarsOneWay);
SmallVector<AnyFunctionType::Param, 4> params;
decomposeTuple(subPatternType, params);
// Remove parameter labels; they aren't used when matching cases,
// but outright conflicts will be checked during coercion.
for (auto &param : params) {
param = param.getWithoutLabels();
}
Type outputType = CS.createTypeVariable(
CS.getConstraintLocator(locator),
TVO_CanBindToNoEscape);
// Equal constraints require ExtInfo comparison.
// FIXME: Verify ExtInfo state is correct, not working by accident.
FunctionType::ExtInfo info;
Type functionType = FunctionType::get(params, outputType, info);
// TODO: Convert to own constraint? Note that ApplicableFn isn't quite
// right, as pattern matching has data flowing *into* the apply result
// and call arguments, not the other way around.
// NOTE: The order here is important! Pattern matching equality is
// not symmetric (we need to fix that either by using a different
// constraint, or actually making it symmetric).
CS.addConstraint(ConstraintKind::Equal, functionType, memberType,
patternLocator);
CS.addConstraint(ConstraintKind::Conversion, outputType, baseType,
patternLocator);
}
return setType(patternType);
}
case PatternKind::Expr: {
// We generate constraints for ExprPatterns in a separate pass. For
// now, just create a type variable.
return setType(CS.createTypeVariable(CS.getConstraintLocator(locator),
TVO_CanBindToNoEscape));
}
}
llvm_unreachable("Unhandled pattern kind");
}
Type visitCaptureListExpr(CaptureListExpr *expr) {
// The type of the capture list is just the type of its closure.
return CS.getType(expr->getClosureBody());
}
Type visitClosureExpr(ClosureExpr *closure) {
auto *locator = CS.getConstraintLocator(closure);
auto closureType = CS.createTypeVariable(locator, TVO_CanBindToNoEscape);
TypeVarRefCollector refCollector(CS, /*DC*/ closure, locator);
// Walk the capture list if this closure has one, because it could
// reference declarations from the outer closure.
if (auto *captureList =
getAsExpr<CaptureListExpr>(CS.getParentExpr(closure))) {
captureList->walk(refCollector);
} else {
closure->walk(refCollector);
}
auto inferredType = inferClosureType(closure);
if (!inferredType || inferredType->hasError())
return Type();
auto referencedVars = refCollector.getTypeVars();
CS.addUnsolvedConstraint(
Constraint::create(CS, ConstraintKind::FallbackType, closureType,
inferredType, locator, referencedVars));
if (!OuterExpansions.empty())
CS.setCapturedExpansions(closure, OuterExpansions);
CS.setClosureType(closure, inferredType);
return closureType;
}
Type visitAutoClosureExpr(AutoClosureExpr *expr) {
// AutoClosureExpr is introduced by CSApply.
llvm_unreachable("Already type-checked");
}
Type visitInOutExpr(InOutExpr *expr) {
// The address-of operator produces an explicit inout T from an lvalue T.
// We model this with the constraint
//
// S < lvalue T
//
// where T is a fresh type variable.
auto lvalue = CS.createTypeVariable(CS.getConstraintLocator(expr),
TVO_CanBindToNoEscape);
auto bound = LValueType::get(lvalue);
auto result = InOutType::get(lvalue);
CS.addConstraint(ConstraintKind::Conversion,
CS.getType(expr->getSubExpr()), bound,
CS.getConstraintLocator(expr));
return result;
}
Type visitVarargExpansionExpr(VarargExpansionExpr *expr) {
// Create a fresh type variable.
auto element = CS.createTypeVariable(CS.getConstraintLocator(expr),
TVO_CanBindToNoEscape);
// Try to build the appropriate type for a variadic argument list of
// the fresh element type. If that failed, just bail out.
auto variadicSeq = VariadicSequenceType::get(element);
// Require the operand to be convertible to the array type.
CS.addConstraint(ConstraintKind::Conversion,
CS.getType(expr->getSubExpr()), variadicSeq,
CS.getConstraintLocator(expr));
return variadicSeq;
}
void collectExpandedPacks(PackExpansionExpr *expansion,
SmallVectorImpl<ASTNode> &packs) {
struct PackCollector : public ASTWalker {
private:
ConstraintSystem &CS;
SmallVectorImpl<ASTNode> &Packs;
public:
PackCollector(ConstraintSystem &cs, SmallVectorImpl<ASTNode> &packs)
: CS(cs), Packs(packs) {}
/// Walk everything that's available.
MacroWalking getMacroWalkingBehavior() const override {
return MacroWalking::ArgumentsAndExpansion;
}
virtual PreWalkResult<Expr *> walkToExprPre(Expr *E) override {
// Don't walk into nested pack expansions
if (isa<PackExpansionExpr>(E)) {
return Action::SkipNode(E);
}
if (isa<PackElementExpr>(E)) {
Packs.push_back(E);
}
if (auto *declRef = dyn_cast<DeclRefExpr>(E)) {
auto type = CS.getTypeIfAvailable(declRef);
if (!type)
return Action::Continue(E);
if (type->is<ElementArchetypeType>() &&
CS.hasFixFor(CS.getConstraintLocator(declRef),
FixKind::IgnoreMissingEachKeyword)) {
auto *packElementExpr =
PackElementExpr::create(CS.getASTContext(),
/*eachLoc=*/{}, declRef,
/*implicit=*/true, type);
Packs.push_back(CS.cacheType(packElementExpr));
}
}
return Action::Continue(E);
}
virtual PreWalkAction walkToTypeReprPre(TypeRepr *T) override {
// Don't walk into nested pack expansions
if (isa<PackExpansionTypeRepr>(T)) {
return Action::SkipNode();
}
if (isa<PackElementTypeRepr>(T)) {
Packs.push_back(T);
}
return Action::Continue();
}
} packCollector(CS, packs);
expansion->getPatternExpr()->walk(packCollector);
}
Type visitPackExpansionExpr(PackExpansionExpr *expr) {
assert(OuterExpansions.back() == expr);
OuterExpansions.pop_back();
auto expansionType = CS.getType(expr)->castTo<PackExpansionType>();
auto elementResultType = CS.getType(expr->getPatternExpr());
CS.addConstraint(ConstraintKind::PackElementOf, elementResultType,
expansionType->getPatternType(),
CS.getConstraintLocator(expr));
// Generate ShapeOf constraints between all packs expanded by this
// pack expansion expression through the shape type variable.
SmallVector<ASTNode, 2> expandedPacks;
collectExpandedPacks(expr, expandedPacks);
if (expandedPacks.empty()) {
(void)CS.recordFix(AllowValueExpansionWithoutPackReferences::create(
CS, CS.getConstraintLocator(expr)));
}
for (auto pack : expandedPacks) {
Type packType;
/// Skipping over pack elements because the relationship to its
/// environment is now established during \c pushPackExpansionExpr
/// upon visiting its pack expansion and the Shape constraint added
/// upon visiting the pack element.
if (isExpr<PackElementExpr>(pack)) {
continue;
} else if (auto *elementType =
getAsTypeRepr<PackElementTypeRepr>(pack)) {
// OpenPackElementType sets types for 'each T' type reprs in
// expressions. Some invalid code won't make it there, and
// the constraint system won't have recorded a type.
if (!CS.hasType(elementType->getPackType()))
return Type();
packType = CS.getType(elementType->getPackType());
} else {
llvm_unreachable("unsupported pack reference ASTNode");
}
auto *elementShape = CS.createTypeVariable(
CS.getConstraintLocator(pack, ConstraintLocator::PackShape),
TVO_CanBindToPack);
CS.addConstraint(
ConstraintKind::ShapeOf, elementShape, packType,
CS.getConstraintLocator(pack, ConstraintLocator::PackShape));
CS.addConstraint(
ConstraintKind::Equal, elementShape, expansionType->getCountType(),
CS.getConstraintLocator(expr, ConstraintLocator::PackShape));
}
return expansionType;
}
Type visitPackElementExpr(PackElementExpr *expr) {
auto packType = CS.getType(expr->getPackRefExpr());
auto *packExpansion = CS.getPackElementExpansion(expr);
auto elementType = openPackElement(
packType, CS.getConstraintLocator(expr), packExpansion);
if (packExpansion) {
auto expansionType =
CS.getType(packExpansion)->castTo<PackExpansionType>();
CS.addConstraint(ConstraintKind::ShapeOf, expansionType->getCountType(),
packType,
CS.getConstraintLocator(packExpansion,
ConstraintLocator::PackShape));
} else {
CS.recordFix(AllowInvalidPackReference::create(
CS, packType, CS.getConstraintLocator(expr->getPackRefExpr())));
}
return elementType;
}
Type visitMaterializePackExpr(MaterializePackExpr *expr) {
llvm_unreachable("MaterializePackExpr already type-checked");
}
Type visitDynamicTypeExpr(DynamicTypeExpr *expr) {
auto tv = CS.createTypeVariable(CS.getConstraintLocator(expr),
TVO_CanBindToNoEscape);
CS.addConstraint(
ConstraintKind::DynamicTypeOf, tv, CS.getType(expr->getBase()),
CS.getConstraintLocator(expr, ConstraintLocator::DynamicType));
return tv;
}
Type visitOpaqueValueExpr(OpaqueValueExpr *expr) {
return expr->getType();
}
Type visitPropertyWrapperValuePlaceholderExpr(
PropertyWrapperValuePlaceholderExpr *expr) {
if (auto ty = expr->getType()) {
CS.cacheType(expr);
return ty;
}
assert(CS.getType(expr));
return CS.getType(expr);
}
Type visitAppliedPropertyWrapperExpr(AppliedPropertyWrapperExpr *expr) {
return expr->getType();
}
Type visitDefaultArgumentExpr(DefaultArgumentExpr *expr) {
return expr->getType();
}
Type visitApplyExpr(ApplyExpr *expr) {
auto fnExpr = expr->getFn();
CS.associateArgumentList(CS.getConstraintLocator(expr), expr->getArgs());
if (auto *UDE = dyn_cast<UnresolvedDotExpr>(fnExpr)) {
auto typeOperation = getTypeOperation(UDE, CS.getASTContext());
if (typeOperation != TypeOperation::None)
return resultOfTypeOperation(typeOperation, expr->getArgs());
}
// The result type is a fresh type variable.
Type resultType = CS.createTypeVariable(
CS.getConstraintLocator(expr, ConstraintLocator::FunctionResult),
TVO_CanBindToNoEscape);
// A direct call to a ClosureExpr makes it noescape.
FunctionType::ExtInfo extInfo;
if (isa<ClosureExpr>(fnExpr->getSemanticsProvidingExpr()))
extInfo = extInfo.withNoEscape();
SmallVector<AnyFunctionType::Param, 8> params;
getMatchingParams(expr->getArgs(), params);
CS.addApplicationConstraint(
FunctionType::get(params, resultType, extInfo), CS.getType(fnExpr),
/*trailingClosureMatching=*/std::nullopt, CurDC,
CS.getConstraintLocator(expr, ConstraintLocator::ApplyFunction));
// If we ended up resolving the result type variable to a concrete type,
// set it as the favored type for this expression.
if (CS.performanceHacksEnabled()) {
Type fixedType =
CS.getFixedTypeRecursive(resultType, /*wantRvalue=*/true);
if (!fixedType->isTypeVariableOrMember()) {
CS.setFavoredType(expr, fixedType.getPointer());
resultType = fixedType;
}
}
return resultType;
}
Type visitRebindSelfInConstructorExpr(RebindSelfInConstructorExpr *expr) {
// The result is void.
return TupleType::getEmpty(CS.getASTContext());
}
Type visitTernaryExpr(TernaryExpr *expr) {
// Condition must convert to Bool.
auto boolDecl = CS.getASTContext().getBoolDecl();
if (!boolDecl)
return Type();
CS.addConstraint(
ConstraintKind::Conversion, CS.getType(expr->getCondExpr()),
boolDecl->getDeclaredInterfaceType(),
CS.getConstraintLocator(expr, ConstraintLocator::Condition));
// The branches must be convertible to a common type.
return CS.addJoinConstraint(
CS.getConstraintLocator(expr),
{{CS.getType(expr->getThenExpr()),
CS.getConstraintLocator(expr, LocatorPathElt::TernaryBranch(true))},
{CS.getType(expr->getElseExpr()),
CS.getConstraintLocator(expr,
LocatorPathElt::TernaryBranch(false))}});
}
virtual Type visitImplicitConversionExpr(ImplicitConversionExpr *expr) {
llvm_unreachable("Already type-checked");
}
Type
createTypeVariableAndDisjunctionForIUOCoercion(Type toType,
ConstraintLocator *locator) {
auto typeVar = CS.createTypeVariable(locator, TVO_CanBindToNoEscape);
CS.buildDisjunctionForImplicitlyUnwrappedOptional(typeVar, toType,
locator);
return typeVar;
}
Type getTypeForCast(ExplicitCastExpr *E) {
if (auto *const repr = E->getCastTypeRepr()) {
// Validate the resulting type.
return resolveTypeReferenceInExpression(
repr, TypeResolverContext::ExplicitCastExpr,
CS.getConstraintLocator(E));
}
assert(E->isImplicit());
return E->getCastType();
}
Type visitForcedCheckedCastExpr(ForcedCheckedCastExpr *expr) {
auto fromExpr = expr->getSubExpr();
if (!fromExpr) // Either wasn't constructed correctly or wasn't folded.
return nullptr;
auto toType = getTypeForCast(expr);
if (!toType)
return Type();
auto *const repr = expr->getCastTypeRepr();
// Cache the type we're casting to.
if (repr) CS.setType(repr, toType);
auto fromType = CS.getType(fromExpr);
auto locator = CS.getConstraintLocator(expr);
// The source type can be checked-cast to the destination type.
CS.addConstraint(ConstraintKind::CheckedCast, fromType, toType, locator);
// If the result type was declared IUO, add a disjunction for
// bindings for the result of the coercion.
if (repr && repr->getKind() == TypeReprKind::ImplicitlyUnwrappedOptional)
return createTypeVariableAndDisjunctionForIUOCoercion(toType, locator);
return toType;
}
Type visitCoerceExpr(CoerceExpr *expr) {
// Validate the resulting type.
auto toType = getTypeForCast(expr);
if (!toType)
return nullptr;
auto *const repr = expr->getCastTypeRepr();
// Cache the type we're casting to.
if (repr) CS.setType(repr, toType);
auto fromType = CS.getType(expr->getSubExpr());
auto locator =
CS.getConstraintLocator(expr, ConstraintLocator::CoercionOperand);
// Literal initialization (e.g. `UInt32(0)`) doesn't require
// a conversion because the literal is supposed to assume the
// `to` type.
//
// `to` type could be a type variable if i.e. the repr is invalid,
// in such cases a slower conversion path is a better choice to
// let it be inferred from the context and/or from the literal itself.
if (expr->isLiteralInit() && !toType->isTypeVariableOrMember()) {
CS.addConstraint(ConstraintKind::Equal, fromType, toType, locator);
} else {
// Add a conversion constraint for the direct conversion between
// types.
CS.addExplicitConversionConstraint(fromType, toType, RememberChoice,
locator);
}
// If the result type was declared IUO, add a disjunction for
// bindings for the result of the coercion.
if (repr &&
repr->getKind() == TypeReprKind::ImplicitlyUnwrappedOptional) {
return createTypeVariableAndDisjunctionForIUOCoercion(
toType, CS.getConstraintLocator(expr));
}
return toType;
}
Type visitConditionalCheckedCastExpr(ConditionalCheckedCastExpr *expr) {
auto fromExpr = expr->getSubExpr();
if (!fromExpr) // Either wasn't constructed correctly or wasn't folded.
return nullptr;
// Validate the resulting type.
const auto toType = getTypeForCast(expr);
if (!toType)
return nullptr;
auto *const repr = expr->getCastTypeRepr();
// Cache the type we're casting to.
if (repr) CS.setType(repr, toType);
auto fromType = CS.getType(fromExpr);
auto locator = CS.getConstraintLocator(expr);
CS.addConstraint(ConstraintKind::CheckedCast, fromType, toType, locator);
// If the result type was declared IUO, add a disjunction for
// bindings for the result of the coercion.
if (repr && repr->getKind() == TypeReprKind::ImplicitlyUnwrappedOptional)
return createTypeVariableAndDisjunctionForIUOCoercion(
OptionalType::get(toType), locator);
return OptionalType::get(toType);
}
Type visitIsExpr(IsExpr *expr) {
auto toType = getTypeForCast(expr);
if (!toType)
return nullptr;
auto *const repr = expr->getCastTypeRepr();
// Cache the type we're checking.
if (repr)
CS.setType(repr, toType);
// Add a checked cast constraint.
auto fromType = CS.getType(expr->getSubExpr());
CS.addConstraint(ConstraintKind::CheckedCast, fromType, toType,
CS.getConstraintLocator(expr));
auto &ctx = CS.getASTContext();
// The result is Bool.
auto boolDecl = ctx.getBoolDecl();
if (!boolDecl) {
ctx.Diags.diagnose(SourceLoc(), diag::broken_stdlib_type, "Bool");
return Type();
}
return boolDecl->getDeclaredInterfaceType();
}
Type visitDiscardAssignmentExpr(DiscardAssignmentExpr *expr) {
auto locator = CS.getConstraintLocator(expr);
auto typeVar = CS.createTypeVariable(locator, TVO_CanBindToNoEscape);
return LValueType::get(typeVar);
}
static Type genAssignDestType(Expr *expr, ConstraintSystem &CS) {
if (auto *TE = dyn_cast<TupleExpr>(expr)) {
SmallVector<TupleTypeElt, 4> destTupleTypes;
for (unsigned i = 0; i != TE->getNumElements(); ++i) {
Type subType = genAssignDestType(TE->getElement(i), CS);
destTupleTypes.push_back(TupleTypeElt(subType, TE->getElementName(i)));
}
return TupleType::get(destTupleTypes, CS.getASTContext());
} else {
auto *locator = CS.getConstraintLocator(expr);
auto exprType = CS.getType(expr);
auto *destTy = CS.createTypeVariable(locator, TVO_CanBindToNoEscape);
CS.addConstraint(ConstraintKind::LValueObject, exprType, destTy,
locator);
return destTy;
}
}
Type visitAssignExpr(AssignExpr *expr) {
// Handle invalid code.
if (!expr->getDest() || !expr->getSrc())
return Type();
Type destTy = genAssignDestType(expr->getDest(), CS);
CS.addConstraint(ConstraintKind::Conversion,
CS.getType(expr->getSrc()), destTy,
CS.getConstraintLocator(expr));
return TupleType::getEmpty(CS.getASTContext());
}
Type visitUnresolvedPatternExpr(UnresolvedPatternExpr *expr) {
// Encountering an UnresolvedPatternExpr here means we have an invalid
// ExprPattern with a Pattern node like 'let x' nested in it. Record a
// fix, and assign ErrorTypes to any VarDecls bound.
auto *locator = CS.getConstraintLocator(expr);
auto *P = expr->getSubPattern();
CS.recordFix(IgnoreInvalidPatternInExpr::create(CS, P, locator));
P->forEachVariable([&](VarDecl *VD) {
CS.setType(VD, ErrorType::get(CS.getASTContext()));
});
return CS.createTypeVariable(locator, TVO_CanBindToHole);
}
/// Get the type T?
///
/// This is not the ideal source location, but it's only used for
/// diagnosing ill-formed standard libraries, so it really isn't
/// worth QoI efforts.
Type getOptionalType(SourceLoc optLoc, Type valueTy) {
auto optTy = TypeChecker::getOptionalType(optLoc, valueTy);
if (optTy->hasError() ||
TypeChecker::requireOptionalIntrinsics(CS.getASTContext(), optLoc))
return Type();
return optTy;
}
Type visitBindOptionalExpr(BindOptionalExpr *expr) {
// The operand must be coercible to T?, and we will have type T.
auto locator = CS.getConstraintLocator(expr);
auto objectTy = CS.createTypeVariable(locator,
TVO_PrefersSubtypeBinding |
TVO_CanBindToLValue |
TVO_CanBindToNoEscape);
// The result is the object type of the optional subexpression.
CS.addConstraint(ConstraintKind::OptionalObject,
CS.getType(expr->getSubExpr()), objectTy,
locator);
return objectTy;
}
Type visitOptionalEvaluationExpr(OptionalEvaluationExpr *expr) {
// The operand must be coercible to T? for some type T. We'd
// like this to be the smallest possible nesting level of
// optional types, e.g. T? over T??; otherwise we don't really
// have a preference.
auto valueTy = CS.createTypeVariable(CS.getConstraintLocator(expr),
TVO_PrefersSubtypeBinding |
TVO_CanBindToNoEscape);
Type optTy = getOptionalType(expr->getSubExpr()->getLoc(), valueTy);
if (!optTy)
return Type();
CS.addConstraint(ConstraintKind::Conversion,
CS.getType(expr->getSubExpr()), optTy,
CS.getConstraintLocator(expr));
return optTy;
}
Type visitForceValueExpr(ForceValueExpr *expr) {
// Force-unwrap an optional of type T? to produce a T.
auto locator = CS.getConstraintLocator(expr);
auto options = TVO_CanBindToLValue | TVO_CanBindToNoEscape;
if (isExpr<UnresolvedDotExpr>(expr->getSubExpr()))
options |= TVO_PrefersSubtypeBinding;
auto objectTy = CS.createTypeVariable(locator, options);
auto *valueExpr = expr->getSubExpr();
// It's invalid to force unwrap `nil` literal e.g. `_ = nil!` or
// `_ = (try nil)!` and similar constructs.
if (auto *nilLiteral = dyn_cast<NilLiteralExpr>(
valueExpr->getSemanticsProvidingExpr())) {
CS.recordFix(SpecifyContextualTypeForNil::create(
CS, CS.getConstraintLocator(nilLiteral)));
}
// The result is the object type of the optional subexpression.
CS.addConstraint(ConstraintKind::OptionalObject, CS.getType(valueExpr),
objectTy, locator);
return objectTy;
}
Type visitOpenExistentialExpr(OpenExistentialExpr *expr) {
llvm_unreachable("Already type-checked");
}
Type visitMakeTemporarilyEscapableExpr(MakeTemporarilyEscapableExpr *expr) {
llvm_unreachable("Already type-checked");
}
Type visitKeyPathApplicationExpr(KeyPathApplicationExpr *expr) {
// This should only appear in already-type-checked solutions, but we may
// need to re-check for failure diagnosis.
auto locator = CS.getConstraintLocator(expr);
auto projectedTy = CS.createTypeVariable(locator,
TVO_CanBindToLValue |
TVO_CanBindToNoEscape);
CS.addKeyPathApplicationConstraint(CS.getType(expr->getKeyPath()),
CS.getType(expr->getBase()),
projectedTy,
locator);
return projectedTy;
}
Type visitEnumIsCaseExpr(EnumIsCaseExpr *expr) {
return CS.getASTContext().getBoolType();
}
Type visitLazyInitializerExpr(LazyInitializerExpr *expr) {
llvm_unreachable("Already type-checked");
}
Type visitEditorPlaceholderExpr(EditorPlaceholderExpr *E) {
auto *locator = CS.getConstraintLocator(E);
if (auto *placeholderRepr = E->getPlaceholderTypeRepr()) {
// Let's try to use specified type, if that's impossible,
// fallback to a type variable.
if (auto preferredTy = resolveTypeReferenceInExpression(
placeholderRepr, TypeResolverContext::InExpression, locator))
return preferredTy;
}
// A placeholder may have any type, but default to Void type if
// otherwise unconstrained.
auto *placeholderTy =
CS.createTypeVariable(locator, TVO_CanBindToNoEscape);
CS.addConstraint(ConstraintKind::Defaultable, placeholderTy,
TupleType::getEmpty(CS.getASTContext()), locator);
return placeholderTy;
}
Type visitObjCSelectorExpr(ObjCSelectorExpr *E) {
// #selector only makes sense when we have the Objective-C
// runtime.
auto &ctx = CS.getASTContext();
if (!ctx.LangOpts.EnableObjCInterop) {
ctx.Diags.diagnose(E->getLoc(), diag::expr_selector_no_objc_runtime);
return nullptr;
}
// Make sure we can reference ObjectiveC.Selector.
// FIXME: Fix-It to add the import?
auto type = CS.getASTContext().getSelectorType();
if (!type) {
ctx.Diags.diagnose(E->getLoc(), diag::expr_selector_module_missing);
return nullptr;
}
return type;
}
Type visitKeyPathExpr(KeyPathExpr *E) {
if (E->isObjC())
return CS.getType(E->getObjCStringLiteralExpr());
auto kpDecl = CS.getASTContext().getKeyPathDecl();
if (!kpDecl) {
auto &de = CS.getASTContext().Diags;
de.diagnose(E->getLoc(), diag::expr_keypath_no_keypath_type);
return ErrorType::get(CS.getASTContext());
}
// For native key paths, traverse the key path components to set up
// appropriate type relationships at each level.
auto rootLocator =
CS.getConstraintLocator(E, ConstraintLocator::KeyPathRoot);
auto locator = CS.getConstraintLocator(E);
auto *root = CS.createTypeVariable(rootLocator, TVO_CanBindToNoEscape |
TVO_CanBindToHole);
// If a root type was explicitly given, then resolve it now.
if (auto rootRepr = E->getExplicitRootType()) {
const auto rootObjectTy = resolveTypeReferenceInExpression(
rootRepr, TypeResolverContext::InExpression, locator);
if (!rootObjectTy || rootObjectTy->hasError())
return Type();
CS.setType(rootRepr, rootObjectTy);
// Allow \Derived.property to be inferred as \Base.property to
// simulate a sort of covariant conversion from
// KeyPath<Derived, T> to KeyPath<Base, T>.
CS.addConstraint(ConstraintKind::Subtype, rootObjectTy, root,
rootLocator);
}
bool didOptionalChain = false;
// We start optimistically from an lvalue base.
Type base = LValueType::get(root);
SmallVector<TypeVariableType *, 2> componentTypeVars;
for (unsigned i : indices(E->getComponents())) {
auto &component = E->getComponents()[i];
auto memberLocator = CS.getConstraintLocator(
locator, LocatorPathElt::KeyPathComponent(i));
auto resultLocator = CS.getConstraintLocator(
memberLocator, ConstraintLocator::KeyPathComponentResult);
switch (auto kind = component.getKind()) {
case KeyPathExpr::Component::Kind::Invalid:
CS.recordFix(IgnoreInvalidASTNode::create(CS, memberLocator));
break;
case KeyPathExpr::Component::Kind::CodeCompletion:
// We don't know what the code completion might resolve to, so we are
// creating a new type variable for its result, which might be a hole.
base = CS.createTypeVariable(
resultLocator,
TVO_CanBindToLValue | TVO_CanBindToNoEscape | TVO_CanBindToHole);
break;
case KeyPathExpr::Component::Kind::UnresolvedMember:
// This should only appear in resolved ASTs, but we may need to
// re-type-check the constraints during failure diagnosis.
case KeyPathExpr::Component::Kind::Member: {
auto memberTy = CS.createTypeVariable(resultLocator,
TVO_CanBindToLValue |
TVO_CanBindToNoEscape);
componentTypeVars.push_back(memberTy);
auto lookupName =
kind == KeyPathExpr::Component::Kind::UnresolvedMember
? DeclNameRef(
component.getUnresolvedDeclName()) // FIXME: type change
// needed
: component.getDeclRef().getDecl()->createNameRef();
auto refKind = component.getFunctionRefInfo();
CS.addValueMemberConstraint(base, lookupName, memberTy, CurDC,
refKind,
/*outerAlternatives=*/{}, memberLocator);
base = memberTy;
break;
}
case KeyPathExpr::Component::Kind::UnresolvedSubscript:
// Subscript should only appear in resolved ASTs, but we may need to
// re-type-check the constraints during failure diagnosis.
case KeyPathExpr::Component::Kind::Subscript: {
auto *args = component.getArgs();
base = addSubscriptConstraints(E, base, /*decl*/ nullptr, args,
memberLocator, &componentTypeVars);
auto &ctx = CS.getASTContext();
// All of the type variables that appear in subscript arguments
// need to be connected to a key path, otherwise it won't be
// possible to determine sendability of the key path type if
// the arguments are disconnected from it before being fully
// resolved.
if (args &&
ctx.LangOpts.hasFeature(Feature::InferSendableFromCaptures)) {
SmallPtrSet<TypeVariableType *, 2> referencedVars;
for (const auto &arg : *args) {
CS.getType(arg.getExpr())->getTypeVariables(referencedVars);
}
componentTypeVars.append(referencedVars.begin(),
referencedVars.end());
}
break;
}
case KeyPathExpr::Component::Kind::UnresolvedApply:
case KeyPathExpr::Component::Kind::Apply: {
base = addApplyConstraints(E, base, component.getArgs(),
memberLocator, &componentTypeVars);
break;
}
case KeyPathExpr::Component::Kind::TupleElement: {
// Note: If implemented, the logic in `getCalleeLocator` will need
// updating to return the correct callee locator for this.
llvm_unreachable("not implemented");
break;
}
case KeyPathExpr::Component::Kind::OptionalChain: {
didOptionalChain = true;
// We can't assign an optional back through an optional chain
// today. Force the base to an rvalue.
auto rvalueTy = CS.createTypeVariable(resultLocator,
TVO_CanBindToNoEscape);
componentTypeVars.push_back(rvalueTy);
CS.addConstraint(ConstraintKind::Equal, base, rvalueTy,
resultLocator);
base = rvalueTy;
LLVM_FALLTHROUGH;
}
case KeyPathExpr::Component::Kind::OptionalForce: {
auto optionalObjTy = CS.createTypeVariable(resultLocator,
TVO_CanBindToLValue |
TVO_CanBindToNoEscape);
componentTypeVars.push_back(optionalObjTy);
CS.addConstraint(ConstraintKind::OptionalObject, base, optionalObjTy,
resultLocator);
base = optionalObjTy;
break;
}
case KeyPathExpr::Component::Kind::OptionalWrap: {
// This should only appear in resolved ASTs, but we may need to
// re-type-check the constraints during failure diagnosis.
base = OptionalType::get(base);
break;
}
case KeyPathExpr::Component::Kind::Identity:
break;
case KeyPathExpr::Component::Kind::DictionaryKey:
llvm_unreachable("DictionaryKey only valid in #keyPath");
break;
}
// By now, `base` is the result type of this component. Set it in the
// constraint system so we can find it later.
CS.setType(E, i, base);
}
auto valueLocator =
CS.getConstraintLocator(E, ConstraintLocator::KeyPathValue);
// If there was an optional chaining component, the end result must be
// optional.
if (didOptionalChain) {
auto objTy = CS.createTypeVariable(locator, TVO_CanBindToNoEscape |
TVO_CanBindToHole);
componentTypeVars.push_back(objTy);
auto optTy = OptionalType::get(objTy);
CS.addConstraint(ConstraintKind::Conversion, base, optTy, valueLocator);
base = optTy;
}
// If we have a malformed KeyPathExpr e.g. let _: KeyPath<A, C> = \A
// let's record a AllowKeyPathMissingComponent fix.
if (E->hasSingleInvalidComponent()) {
(void)CS.recordFix(AllowKeyPathWithoutComponents::create(CS, locator));
}
auto *value = CS.createTypeVariable(valueLocator, TVO_CanBindToNoEscape |
TVO_CanBindToHole);
CS.addConstraint(ConstraintKind::Equal, base, value, valueLocator);
CS.recordKeyPath(E, root, value, CurDC);
// The result is a KeyPath from the root to the end component.
// The type of key path depends on the overloads chosen for the key
// path components.
auto typeLoc =
CS.getConstraintLocator(locator, LocatorPathElt::KeyPathType());
Type kpTy = CS.createTypeVariable(typeLoc, TVO_CanBindToNoEscape |
TVO_CanBindToHole);
CS.addKeyPathConstraint(kpTy, root, value, componentTypeVars, locator);
// Add a fallback constraint so we have an anchor to use for
// capability inference when there is no context.
CS.addUnsolvedConstraint(Constraint::create(
CS, ConstraintKind::FallbackType, kpTy,
BoundGenericType::get(kpDecl, /*parent=*/Type(), {root, value}),
CS.getConstraintLocator(E, ConstraintLocator::FallbackType)));
return kpTy;
}
Type visitCurrentContextIsolationExpr(CurrentContextIsolationExpr *E) {
// If this was expanded from the builtin `#isolation` macro, it
// already has a type.
if (auto type = E->getType())
return type;
// Otherwise, this was created for a `for await` loop, where its
// type is always `(any Actor)?`.
auto actorProto = CS.getASTContext().getProtocol(
KnownProtocolKind::Actor);
return OptionalType::get(actorProto->getDeclaredExistentialType());
}
Type visitExtractFunctionIsolationExpr(ExtractFunctionIsolationExpr *E) {
llvm_unreachable("found ExtractFunctionIsolationExpr in CSGen");
}
Type visitKeyPathDotExpr(KeyPathDotExpr *E) {
llvm_unreachable("found KeyPathDotExpr in CSGen");
}
Type visitSingleValueStmtExpr(SingleValueStmtExpr *E) {
llvm_unreachable("Handled by the walker directly");
}
Type visitTapExpr(TapExpr *expr) {
DeclContext *varDC = expr->getVar()->getDeclContext();
ASSERT(varDC != nullptr);
ASSERT((varDC == CS.DC ||
isa<AbstractClosureExpr>(varDC) ||
varDC->isChildContextOf(CS.DC)) &&
"TapExpr var should be in the same DeclContext we're checking it in!");
auto locator = CS.getConstraintLocator(expr);
auto tv = CS.createTypeVariable(locator, TVO_CanBindToNoEscape);
if (auto subExpr = expr->getSubExpr()) {
auto subExprType = CS.getType(subExpr);
CS.addConstraint(ConstraintKind::Bind, subExprType, tv, locator);
}
return tv;
}
Type visitTypeJoinExpr(TypeJoinExpr *expr) {
auto *locator = CS.getConstraintLocator(expr);
SmallVector<std::pair<Type, ConstraintLocator *>, 4> elements;
elements.reserve(expr->getNumElements());
if (auto *SVE = expr->getSingleValueStmtExpr()) {
// If we have a SingleValueStmtExpr, form a join of the branch types.
SmallVector<Expr *, 4> scratch;
auto branches = SVE->getResultExprs(scratch);
for (auto idx : indices(branches)) {
auto *eltLoc = CS.getConstraintLocator(
SVE, {LocatorPathElt::SingleValueStmtResult(idx)});
elements.emplace_back(CS.getType(branches[idx]), eltLoc);
}
} else {
for (auto *element : expr->getElements()) {
elements.emplace_back(CS.getType(element),
CS.getConstraintLocator(element));
}
}
Type resultTy;
if (auto *var = expr->getVar()) {
resultTy = CS.getType(var);
} else {
resultTy = expr->getType();
}
assert(resultTy);
// If we have a single branch of a SingleValueStmtExpr, we want a
// conversion of the result, not a join, which would skip the conversion.
// This is needed to ensure we apply the Void/Never conversions.
if (elements.size() == 1 && expr->getSingleValueStmtExpr()) {
auto &elt = elements[0];
CS.addConstraint(ConstraintKind::Conversion, elt.first,
resultTy, elt.second);
return resultTy;
}
// The type of a join expression is obtained by performing
// a "join-meet" operation on deduced types of its elements
// and the underlying variable.
auto joinedTy = CS.addJoinConstraint(locator, elements);
CS.addConstraint(ConstraintKind::Equal, resultTy, joinedTy, locator);
return resultTy;
}
/// Lookup all macros with the given macro name.
SmallVector<OverloadChoice, 1> lookupMacros(DeclName moduleName,
DeclName macroName,
FunctionRefInfo functionRefInfo,
MacroRoles roles) {
SmallVector<OverloadChoice, 1> choices;
auto results = namelookup::lookupMacros(CurDC, DeclNameRef(moduleName),
DeclNameRef(macroName), roles);
for (const auto &result : results) {
// Ignore invalid results. This matches the OverloadedDeclRefExpr
// logic.
if (result->isInvalid())
continue;
auto choice = OverloadChoice::getDecl(result, functionRefInfo);
choices.push_back(choice);
}
// FIXME: At some point, we need to check for function-like macros without
// arguments and vice-versa.
return choices;
}
Type visitMacroExpansionExpr(MacroExpansionExpr *expr) {
// Assign a discriminator.
(void)expr->getDiscriminator();
auto &ctx = CS.getASTContext();
auto locator = CS.getConstraintLocator(expr);
CS.associateArgumentList(locator, expr->getArgs());
// Look up the macros with this name.
auto moduleIdent = expr->getModuleName().getBaseName();
auto macroIdent = expr->getMacroName().getBaseName();
FunctionRefInfo functionRefInfo = FunctionRefInfo::singleBaseNameApply();
auto macros = lookupMacros(moduleIdent, macroIdent, functionRefInfo,
expr->getMacroRoles());
if (macros.empty()) {
ctx.Diags.diagnose(expr->getMacroNameLoc(), diag::macro_undefined,
macroIdent)
.highlight(expr->getMacroNameLoc().getSourceRange());
return Type();
}
// Introduce an overload set for the macro reference.
auto macroRefType = Type(CS.createTypeVariable(locator, 0));
CS.addOverloadSet(macroRefType, macros, CurDC, locator);
// Add explicit generic arguments, if there were any.
if (expr->getGenericArgsRange().isValid()) {
addSpecializationConstraint(CS.getConstraintLocator(expr), macroRefType,
expr->getGenericArgsRange().Start,
expr->getGenericArgs());
}
// Form the applicable-function constraint. The result type
// is the result of that call.
SmallVector<AnyFunctionType::Param, 8> params;
getMatchingParams(expr->getArgs(), params);
Type resultType = CS.createTypeVariable(
CS.getConstraintLocator(expr, ConstraintLocator::FunctionResult),
TVO_CanBindToNoEscape);
CS.addApplicationConstraint(
FunctionType::get(params, resultType),
macroRefType,
/*trailingClosureMatching=*/std::nullopt,
CurDC,
CS.getConstraintLocator(
expr, ConstraintLocator::ApplyFunction));
return resultType;
}
static bool isTriggerFallbackDiagnosticBuiltin(UnresolvedDotExpr *UDE,
ASTContext &Context) {
auto *DRE = dyn_cast<DeclRefExpr>(UDE->getBase());
if (!DRE)
return false;
if (DRE->getDecl() != Context.TheBuiltinModule)
return false;
auto member = UDE->getName().getBaseName().userFacingName();
return member == "trigger_fallback_diagnostic";
}
enum class TypeOperation { None,
Join,
JoinInout,
JoinMeta,
JoinNonexistent,
};
static TypeOperation getTypeOperation(UnresolvedDotExpr *UDE,
ASTContext &Context) {
auto *DRE = dyn_cast<DeclRefExpr>(UDE->getBase());
if (!DRE)
return TypeOperation::None;
if (DRE->getDecl() != Context.TheBuiltinModule)
return TypeOperation::None;
return llvm::StringSwitch<TypeOperation>(
UDE->getName().getBaseIdentifier().str())
.Case("type_join", TypeOperation::Join)
.Case("type_join_inout", TypeOperation::JoinInout)
.Case("type_join_meta", TypeOperation::JoinMeta)
.Case("type_join_nonexistent", TypeOperation::JoinNonexistent)
.Default(TypeOperation::None);
}
Type resultOfTypeOperation(TypeOperation op, ArgumentList *Args) {
auto *lhs = Args->getExpr(0);
auto *rhs = Args->getExpr(1);
switch (op) {
case TypeOperation::None:
llvm_unreachable(
"We should have a valid type operation at this point!");
case TypeOperation::Join: {
auto lhsMeta = CS.getType(lhs)->getAs<MetatypeType>();
auto rhsMeta = CS.getType(rhs)->getAs<MetatypeType>();
if (!lhsMeta || !rhsMeta)
llvm_unreachable("Unexpected argument types for Builtin.type_join!");
auto &ctx = lhsMeta->getASTContext();
auto join =
Type::join(lhsMeta->getInstanceType(), rhsMeta->getInstanceType());
if (!join)
return ErrorType::get(ctx);
return MetatypeType::get(*join, ctx)->getCanonicalType();
}
case TypeOperation::JoinInout: {
auto lhsInOut = CS.getType(lhs)->getAs<InOutType>();
auto rhsMeta = CS.getType(rhs)->getAs<MetatypeType>();
if (!lhsInOut || !rhsMeta)
llvm_unreachable("Unexpected argument types for Builtin.type_join!");
auto &ctx = lhsInOut->getASTContext();
auto join =
Type::join(lhsInOut, rhsMeta->getInstanceType());
if (!join)
return ErrorType::get(ctx);
return MetatypeType::get(*join, ctx)->getCanonicalType();
}
case TypeOperation::JoinMeta: {
auto lhsMeta = CS.getType(lhs)->getAs<MetatypeType>();
auto rhsMeta = CS.getType(rhs)->getAs<MetatypeType>();
if (!lhsMeta || !rhsMeta)
llvm_unreachable("Unexpected argument types for Builtin.type_join!");
auto &ctx = lhsMeta->getASTContext();
auto join = Type::join(lhsMeta, rhsMeta);
if (!join)
return ErrorType::get(ctx);
return *join;
}
case TypeOperation::JoinNonexistent: {
auto lhsMeta = CS.getType(lhs)->getAs<MetatypeType>();
auto rhsMeta = CS.getType(rhs)->getAs<MetatypeType>();
if (!lhsMeta || !rhsMeta)
llvm_unreachable("Unexpected argument types for Builtin.type_join_nonexistent!");
auto &ctx = lhsMeta->getASTContext();
auto join =
Type::join(lhsMeta->getInstanceType(), rhsMeta->getInstanceType());
// Verify that we could not compute a join.
if (join)
llvm_unreachable("Unexpected result from join - it should not have been computable!");
// The return value is unimportant.
return MetatypeType::get(ctx.getAnyExistentialType())->getCanonicalType();
}
}
llvm_unreachable("unhandled operation");
}
/// Assuming that we are solving for code completion, assign \p expr a fresh
/// and unconstrained type variable as its type.
void setTypeForArgumentIgnoredForCompletion(Expr *expr) {
assert(CS.isForCodeCompletion());
ConstraintSystem &CS = getConstraintSystem();
if (auto closure = dyn_cast<ClosureExpr>(expr)) {
FunctionType *closureTy =
inferClosureType(closure, /*allowResultBindToHole=*/true);
CS.setClosureType(closure, closureTy);
CS.setType(closure, closureTy);
} else {
TypeVariableType *exprType = CS.createTypeVariable(
CS.getConstraintLocator(expr),
TVO_CanBindToLValue | TVO_CanBindToInOut | TVO_CanBindToNoEscape |
TVO_CanBindToHole);
CS.setType(expr, exprType);
}
}
};
class ConstraintWalker : public ASTWalker {
ConstraintGenerator &CG;
public:
ConstraintWalker(ConstraintGenerator &CG) : CG(CG) { }
MacroWalking getMacroWalkingBehavior() const override {
return MacroWalking::Arguments;
}
PreWalkResult<Expr *> walkToExprPre(Expr *expr) override {
auto &CS = CG.getConstraintSystem();
if (CS.isArgumentIgnoredForCodeCompletion(expr)) {
CG.setTypeForArgumentIgnoredForCompletion(expr);
return Action::SkipNode(expr);
}
if (auto *SVE = dyn_cast<SingleValueStmtExpr>(expr)) {
if (CS.generateConstraints(SVE))
return Action::Stop();
return Action::SkipNode(expr);
}
// Note that the subexpression of a #selector expression is
// unevaluated.
if (auto sel = dyn_cast<ObjCSelectorExpr>(expr)) {
auto *subExpr = sel->getSubExpr()->getSemanticsProvidingExpr();
CG.getConstraintSystem().UnevaluatedRootExprs.insert(subExpr);
}
// Check an objc key-path expression, which fills in its semantic
// expression as a string literal.
if (auto keyPath = dyn_cast<KeyPathExpr>(expr)) {
if (keyPath->isObjC()) {
auto &cs = CG.getConstraintSystem();
(void)TypeChecker::checkObjCKeyPathExpr(cs.DC, keyPath);
}
}
// Generate constraints for each of the entries in the capture list.
if (auto captureList = dyn_cast<CaptureListExpr>(expr)) {
TypeChecker::diagnoseDuplicateCaptureVars(captureList);
}
// Both multi- and single-statement closures now behave the same way
// when it comes to constraint generation.
if (auto closure = dyn_cast<ClosureExpr>(expr)) {
auto &CS = CG.getConstraintSystem();
auto closureType = CG.visitClosureExpr(closure);
if (!closureType)
return Action::Stop();
CS.setType(expr, closureType);
return Action::SkipNode(expr);
}
// Don't visit CoerceExpr with an empty sub expression. They may occur
// if the body of a closure was not visited while pre-checking because
// of an error in the closure's signature.
if (auto coerceExpr = dyn_cast<CoerceExpr>(expr)) {
if (!coerceExpr->getSubExpr()) {
return Action::SkipNode(expr);
}
}
// Don't visit TernaryExpr with empty sub expressions. They may occur
// if the body of a closure was not visited while pre-checking because
// of an error in the closure's signature.
if (auto *ternary = dyn_cast<TernaryExpr>(expr)) {
if (!ternary->getThenExpr() || !ternary->getElseExpr())
return Action::SkipNode(expr);
}
if (CS.isForCodeCompletion()) {
SmallVector<Expr *, 2> ignoredArgs;
getArgumentsAfterCodeCompletionToken(expr, CS, ignoredArgs);
for (auto ignoredArg : ignoredArgs) {
CS.markArgumentIgnoredForCodeCompletion(ignoredArg);
}
}
if (auto *expansion = dyn_cast<PackExpansionExpr>(expr)) {
CG.pushPackExpansionExpr(expansion);
}
return Action::Continue(expr);
}
/// Once we've visited the children of the given expression,
/// generate constraints from the expression.
PostWalkResult<Expr *> walkToExprPost(Expr *expr) override {
auto &CS = CG.getConstraintSystem();
// Translate special type-checker Builtin calls into simpler expressions.
if (auto *apply = dyn_cast<ApplyExpr>(expr)) {
auto fnExpr = apply->getFn();
if (auto *UDE = dyn_cast<UnresolvedDotExpr>(fnExpr)) {
auto typeOperation =
ConstraintGenerator::getTypeOperation(UDE, CS.getASTContext());
if (typeOperation !=
ConstraintGenerator::TypeOperation::None) {
// Handle the Builtin.type_join* family of calls by replacing
// them with dot_self_expr of type_expr with the type being the
// result of the join.
auto joinMetaTy =
CG.resultOfTypeOperation(typeOperation, apply->getArgs());
auto joinTy = joinMetaTy->castTo<MetatypeType>();
auto *TE = TypeExpr::createImplicit(joinTy->getInstanceType(),
CS.getASTContext());
CS.cacheType(TE);
auto *DSE = new (CS.getASTContext())
DotSelfExpr(TE, SourceLoc(), SourceLoc(), CS.getType(TE));
DSE->setImplicit();
CS.cacheType(DSE);
return Action::Continue(DSE);
}
}
}
if (auto type = CG.visit(expr)) {
auto simplifiedType = CS.simplifyType(type);
CS.setType(expr, simplifiedType);
return Action::Continue(expr);
}
return Action::Stop();
}
/// Ignore statements.
PreWalkResult<Stmt *> walkToStmtPre(Stmt *stmt) override {
return Action::SkipNode(stmt);
}
/// Ignore declarations.
PreWalkAction walkToDeclPre(Decl *decl) override {
return Action::SkipNode();
}
};
} // end anonymous namespace
static Expr *generateConstraintsFor(ConstraintSystem &cs, Expr *expr,
DeclContext *DC) {
// Walk the expression, generating constraints.
ConstraintGenerator cg(cs, DC);
ConstraintWalker cw(cg);
Expr *result = expr->walk(cw);
if (result)
cs.optimizeConstraints(result);
return result;
}
bool ConstraintSystem::generateWrappedPropertyTypeConstraints(
VarDecl *wrappedVar, Type initializerType, Type propertyType) {
Type wrappedValueType;
Type wrapperType;
auto wrapperAttributes = wrappedVar->getAttachedPropertyWrappers();
for (unsigned i : indices(wrapperAttributes)) {
// FIXME: We should somehow pass an OpenUnboundGenericTypeFn to
// AttachedPropertyWrapperTypeRequest::evaluate to open up unbound
// generics on the fly.
Type rawWrapperType = wrappedVar->getAttachedPropertyWrapperType(i);
auto wrapperInfo = wrappedVar->getAttachedPropertyWrapperTypeInfo(i);
if (rawWrapperType->hasError() || !wrapperInfo)
return true;
auto *typeExpr = wrapperAttributes[i]->getTypeExpr();
if (!wrappedValueType) {
// Equate the outermost wrapper type to the initializer type.
auto *locator = getConstraintLocator(typeExpr);
wrapperType =
replaceInferableTypesWithTypeVars(rawWrapperType, locator);
if (initializerType)
addConstraint(ConstraintKind::Equal, wrapperType, initializerType, locator);
} else {
// The former wrappedValue type must be equal to the current wrapper type
auto *locator = getConstraintLocator(
typeExpr, LocatorPathElt::WrappedValue(wrapperType));
wrapperType =
replaceInferableTypesWithTypeVars(rawWrapperType, locator);
addConstraint(ConstraintKind::Equal, wrapperType, wrappedValueType, locator);
}
setType(typeExpr, wrapperType);
wrappedValueType = wrapperType->getTypeOfMember(
wrapperInfo.valueVar);
}
// The property type must be equal to the wrapped value type
addConstraint(
ConstraintKind::Equal, propertyType, wrappedValueType,
getConstraintLocator(
wrappedVar, LocatorPathElt::ContextualType(CTP_WrappedProperty)));
ContextualTypeInfo contextInfo(wrappedValueType, CTP_WrappedProperty);
setContextualInfo(wrappedVar, contextInfo);
return false;
}
/// Generate additional constraints for the pattern of an initialization.
static bool generateInitPatternConstraints(ConstraintSystem &cs,
SyntacticElementTarget target,
Expr *initializer) {
auto locator = cs.getConstraintLocator(
initializer, LocatorPathElt::ContextualType(CTP_Initialization));
Type patternType;
if (auto pattern = target.getInitializationPattern()) {
patternType = cs.generateConstraints(
pattern, locator, target.shouldBindPatternVarsOneWay(),
target.getInitializationPatternBindingDecl(),
target.getInitializationPatternBindingIndex());
} else {
patternType = cs.createTypeVariable(locator, TVO_CanBindToNoEscape);
}
if (auto wrappedVar = target.getInitializationWrappedVar())
return cs.generateWrappedPropertyTypeConstraints(
wrappedVar, cs.getType(target.getAsExpr()), patternType);
// Add a conversion constraint between the types.
cs.addConstraint(ConstraintKind::Conversion, cs.getType(target.getAsExpr()),
patternType, locator, /*isFavored*/true);
return false;
}
/// Generate constraints for a for-in statement preamble where the expression
/// is a `PackExpansionExpr`.
static std::optional<PackIterationInfo>
generateForEachStmtConstraints(ConstraintSystem &cs, DeclContext *dc,
PackExpansionExpr *expansion, Type patternType) {
auto packIterationInfo = PackIterationInfo();
auto elementLocator = cs.getConstraintLocator(
expansion, ConstraintLocator::SequenceElementType);
{
SyntacticElementTarget target(expansion, dc, CTP_Unused,
/*contextualType=*/Type(),
/*isDiscarded=*/false);
if (cs.generateConstraints(target))
return std::nullopt;
cs.setTargetFor(expansion, target);
}
auto elementType = cs.getType(expansion->getPatternExpr());
cs.addConstraint(ConstraintKind::Conversion, elementType, patternType,
elementLocator);
packIterationInfo.patternType = patternType;
return packIterationInfo;
}
/// Generate constraints for a for-in statement preamble, expecting an
/// expression that conforms to `Swift.Sequence`.
static std::optional<SequenceIterationInfo>
generateForEachStmtConstraints(ConstraintSystem &cs, DeclContext *dc,
ForEachStmt *stmt, Pattern *typeCheckedPattern,
bool shouldBindPatternVarsOneWay) {
ASTContext &ctx = cs.getASTContext();
bool isAsync = stmt->getAwaitLoc().isValid();
auto *sequenceExpr = stmt->getParsedSequence();
// If we have an unsafe expression for the sequence, lift it out of the
// sequence expression. We'll put it back after we've introduced the
// various calls.
UnsafeExpr *unsafeExpr = dyn_cast<UnsafeExpr>(sequenceExpr);
if (unsafeExpr) {
sequenceExpr = unsafeExpr->getSubExpr();
}
auto contextualLocator = cs.getConstraintLocator(
sequenceExpr, LocatorPathElt::ContextualType(CTP_ForEachSequence));
auto elementLocator = cs.getConstraintLocator(
sequenceExpr, ConstraintLocator::SequenceElementType);
auto sequenceIterationInfo = SequenceIterationInfo();
// The expression type must conform to the Sequence protocol.
auto sequenceProto = TypeChecker::getProtocol(
cs.getASTContext(), stmt->getForLoc(),
isAsync ? KnownProtocolKind::AsyncSequence : KnownProtocolKind::Sequence);
if (!sequenceProto)
return std::nullopt;
std::string name;
{
if (auto np = dyn_cast_or_null<NamedPattern>(stmt->getPattern()))
name = "$"+np->getBoundName().str().str();
name += "$generator";
}
auto *makeIteratorVar = new (ctx)
VarDecl(/*isStatic=*/false, VarDecl::Introducer::Var,
sequenceExpr->getStartLoc(), ctx.getIdentifier(name), dc);
makeIteratorVar->setImplicit();
// FIXME: Apply `nonisolated(unsafe)` to async iterators.
//
// Async iterators are not `Sendable`; they're only meant to be used from
// the isolation domain that creates them. But the `next()` method runs on
// the generic executor, so calling it from an actor-isolated context passes
// non-`Sendable` state across the isolation boundary. `next()` should
// inherit the isolation of the caller, but for now, use the opt out.
if (isAsync) {
auto *nonisolated =
NonisolatedAttr::createImplicit(ctx, NonIsolatedModifier::Unsafe);
makeIteratorVar->getAttrs().add(nonisolated);
}
// First, let's form a call from sequence to `.makeIterator()` and save
// that in a special variable which is going to be used by SILGen.
{
FuncDecl *makeIterator = isAsync ? ctx.getAsyncSequenceMakeAsyncIterator()
: ctx.getSequenceMakeIterator();
auto *makeIteratorRef = new (ctx) UnresolvedDotExpr(
sequenceExpr, SourceLoc(), DeclNameRef(makeIterator->getName()),
DeclNameLoc(stmt->getForLoc()), /*implicit=*/true);
makeIteratorRef->setFunctionRefInfo(FunctionRefInfo::singleBaseNameApply());
Expr *makeIteratorCall =
CallExpr::createImplicitEmpty(ctx, makeIteratorRef);
// Swap in the 'unsafe' expression.
if (unsafeExpr) {
unsafeExpr->setSubExpr(makeIteratorCall);
makeIteratorCall = unsafeExpr;
}
Pattern *pattern = NamedPattern::createImplicit(ctx, makeIteratorVar);
auto *PB = PatternBindingDecl::createImplicit(
ctx, StaticSpellingKind::None, pattern, makeIteratorCall, dc);
auto makeIteratorTarget = SyntacticElementTarget::forInitialization(
makeIteratorCall, /*patternType=*/Type(), PB, /*index=*/0,
/*shouldBindPatternsOneWay=*/false);
ContextualTypeInfo contextInfo(sequenceProto->getDeclaredInterfaceType(),
CTP_ForEachSequence);
cs.setContextualInfo(sequenceExpr, contextInfo);
if (cs.generateConstraints(makeIteratorTarget))
return std::nullopt;
sequenceIterationInfo.makeIteratorVar = PB;
// Type of sequence expression has to conform to Sequence protocol.
//
// Note that the following emulates having `$generator` separately
// type-checked by introducing a `TVO_PrefersSubtypeBinding` type
// variable that would make sure that result of `.makeIterator` would
// get ranked standalone.
{
auto *externalIteratorType = cs.createTypeVariable(
cs.getConstraintLocator(sequenceExpr), TVO_PrefersSubtypeBinding);
cs.addConstraint(ConstraintKind::Equal, externalIteratorType,
cs.getType(sequenceExpr),
externalIteratorType->getImpl().getLocator());
cs.addConstraint(ConstraintKind::ConformsTo, externalIteratorType,
sequenceProto->getDeclaredInterfaceType(),
contextualLocator);
sequenceIterationInfo.sequenceType = cs.getType(sequenceExpr);
}
cs.setTargetFor({PB, /*index=*/0}, makeIteratorTarget);
}
// Now, result type of `.makeIterator()` is used to form a call to
// `.next()`. `next()` is called on each iteration of the loop.
{
FuncDecl *nextFn =
TypeChecker::getForEachIteratorNextFunction(dc, stmt->getForLoc(), isAsync);
Identifier nextId = nextFn ? nextFn->getName().getBaseIdentifier()
: ctx.Id_next;
TinyPtrVector<Identifier> labels;
if (nextFn && nextFn->getParameters()->size() == 1)
labels.push_back(ctx.Id_isolation);
auto *makeIteratorVarRef =
new (ctx) DeclRefExpr(makeIteratorVar, DeclNameLoc(stmt->getForLoc()),
/*Implicit=*/true);
auto *nextRef = new (ctx)
UnresolvedDotExpr(makeIteratorVarRef, SourceLoc(),
DeclNameRef(DeclName(ctx, nextId, labels)),
DeclNameLoc(stmt->getForLoc()), /*implicit=*/true);
nextRef->setFunctionRefInfo(FunctionRefInfo::singleBaseNameApply());
ArgumentList *nextArgs;
if (nextFn && nextFn->getParameters()->size() == 1) {
auto isolationArg =
new (ctx) CurrentContextIsolationExpr(stmt->getForLoc(), Type());
nextArgs = ArgumentList::createImplicit(
ctx, {Argument(SourceLoc(), ctx.Id_isolation, isolationArg)});
} else {
nextArgs = ArgumentList::createImplicit(ctx, {});
}
Expr *nextCall = CallExpr::createImplicit(ctx, nextRef, nextArgs);
// `next` is always async but witness might not be throwing
if (isAsync) {
nextCall =
AwaitExpr::createImplicit(ctx, nextCall->getLoc(), nextCall);
}
// Wrap the 'next' call in 'unsafe', if the for..in loop has that
// effect or if the loop is async (in which case the iterator variable
// is nonisolated(unsafe).
if (stmt->getUnsafeLoc().isValid() ||
(isAsync &&
ctx.LangOpts.StrictConcurrencyLevel == StrictConcurrency::Complete)) {
SourceLoc loc = stmt->getUnsafeLoc();
bool implicit = stmt->getUnsafeLoc().isInvalid();
if (loc.isInvalid())
loc = stmt->getForLoc();
nextCall = new (ctx) UnsafeExpr(loc, nextCall, Type(), implicit);
}
// The iterator type must conform to IteratorProtocol.
{
ProtocolDecl *iteratorProto = TypeChecker::getProtocol(
cs.getASTContext(), stmt->getForLoc(),
isAsync ? KnownProtocolKind::AsyncIteratorProtocol
: KnownProtocolKind::IteratorProtocol);
if (!iteratorProto)
return std::nullopt;
ContextualTypeInfo contextInfo(iteratorProto->getDeclaredInterfaceType(),
CTP_ForEachSequence);
cs.setContextualInfo(nextRef->getBase(), contextInfo);
}
SyntacticElementTarget nextTarget(nextCall, dc, CTP_Unused,
/*contextualType=*/Type(),
/*isDiscarded=*/false);
if (cs.generateConstraints(nextTarget, FreeTypeVariableBinding::Disallow))
return std::nullopt;
sequenceIterationInfo.nextCall = nextTarget.getAsExpr();
cs.setTargetFor(sequenceIterationInfo.nextCall, nextTarget);
}
// Generate constraints for the pattern.
Type initType =
cs.generateConstraints(typeCheckedPattern, elementLocator,
shouldBindPatternVarsOneWay, nullptr, 0);
if (!initType)
return std::nullopt;
// Add a conversion constraint between the element type of the sequence
// and the type of the element pattern.
auto *elementTypeLoc = cs.getConstraintLocator(
elementLocator, ConstraintLocator::OptionalInjection);
auto elementType = cs.createTypeVariable(elementTypeLoc,
/*flags=*/0);
{
auto nextType = cs.getType(sequenceIterationInfo.nextCall);
cs.addConstraint(ConstraintKind::OptionalObject, nextType, elementType,
elementTypeLoc);
cs.addConstraint(ConstraintKind::Conversion, elementType, initType,
elementLocator);
}
// Populate all of the information for a for-each loop.
sequenceIterationInfo.elementType = elementType;
sequenceIterationInfo.initType = initType;
return sequenceIterationInfo;
}
static std::optional<SyntacticElementTarget>
generateForEachPreambleConstraints(ConstraintSystem &cs,
SyntacticElementTarget target) {
ForEachStmt *stmt = target.getAsForEachStmt();
auto *forEachExpr = stmt->getParsedSequence();
auto *dc = target.getDeclContext();
auto elementLocator = cs.getConstraintLocator(
forEachExpr, ConstraintLocator::SequenceElementType);
Pattern *pattern = TypeChecker::resolvePattern(stmt->getPattern(), dc,
/*isStmtCondition*/ false);
if (!pattern)
return std::nullopt;
target.setPattern(pattern);
if (isa<PackExpansionExpr>(forEachExpr)) {
auto *expansion = cast<PackExpansionExpr>(forEachExpr);
// Generate constraints for the pattern.
Type patternType = cs.generateConstraints(
pattern, elementLocator, target.shouldBindPatternVarsOneWay(), nullptr,
0);
if (!patternType)
return std::nullopt;
if (auto whereClause = stmt->getWhere()) {
cs.recordFix(IgnoreWhereClauseInPackIteration::create(
cs, cs.getConstraintLocator(whereClause)));
}
auto packIterationInfo =
generateForEachStmtConstraints(cs, dc, expansion, patternType);
if (!packIterationInfo) {
return std::nullopt;
}
target.getForEachStmtInfo() = *packIterationInfo;
} else {
auto sequenceIterationInfo = generateForEachStmtConstraints(
cs, dc, stmt, pattern, target.shouldBindPatternVarsOneWay());
if (!sequenceIterationInfo) {
return std::nullopt;
}
target.getForEachStmtInfo() = *sequenceIterationInfo;
}
return target;
}
bool ConstraintSystem::generateConstraints(
SyntacticElementTarget &target,
FreeTypeVariableBinding allowFreeTypeVariables) {
if (Expr *expr = target.getAsExpr()) {
// If the target requires an optional of some type, form a new appropriate
// type variable and update the target's type with an optional of that
// type variable.
if (target.isOptionalSomePatternInit()) {
assert(!target.getExprContextualType() &&
"some pattern cannot have contextual type pre-configured");
auto *convertTypeLocator = getConstraintLocator(
expr, LocatorPathElt::ContextualType(
target.getExprContextualTypePurpose()));
Type var = createTypeVariable(convertTypeLocator, TVO_CanBindToNoEscape);
target.setExprConversionType(TypeChecker::getOptionalType(expr->getLoc(), var));
}
// If we have a parent return statement, record whether it's implied.
if (auto *RS = target.getParentReturnStmt()) {
if (RS->isImplied())
recordImpliedResult(expr, ImpliedResultKind::Regular);
}
expr = buildTypeErasedExpr(expr, target.getDeclContext(),
target.getExprContextualType(),
target.getExprContextualTypePurpose());
// Generate constraints for the main system.
expr = generateConstraints(expr, target.getDeclContext());
if (!expr)
return true;
target.setExpr(expr);
// If there is a type that we're expected to convert to, add the conversion
// constraint.
if (Type convertType = target.getExprConversionType()) {
ContextualTypePurpose ctp = target.getExprContextualTypePurpose();
// If a custom locator wasn't specified, create a locator anchored on
// the expression itself.
auto *convertTypeLocator = target.getExprConvertTypeLocator();
if (!convertTypeLocator) {
convertTypeLocator =
getConstraintLocator(expr, LocatorPathElt::ContextualType(ctp));
}
// If the contextual type has an error, we can't apply the solution.
// Record a fix for an invalid AST node.
if (convertType->hasError())
recordFix(IgnoreInvalidASTNode::create(*this, convertTypeLocator));
// Substitute type variables in for placeholder and error types.
convertType =
convertType.transformRec([&](Type type) -> std::optional<Type> {
auto *tyPtr = type.getPointer();
// Open a type variable for a placeholder type repr. Note we don't
// do this for arbitrary placeholders since they may be existing
// holes when e.g generating the constraints for a ReturnStmt in a
// closure.
if (auto *placeholderTy = dyn_cast<PlaceholderType>(tyPtr)) {
auto originator = placeholderTy->getOriginator();
auto *typeRepr = originator.dyn_cast<TypeRepr *>();
if (!isa_and_nonnull<PlaceholderTypeRepr>(typeRepr))
return std::nullopt;
auto *loc = getConstraintLocator(
convertTypeLocator,
LocatorPathElt::PlaceholderType(typeRepr));
return createTypeVariable(loc, TVO_CanBindToNoEscape |
TVO_PrefersSubtypeBinding |
TVO_CanBindToHole);
}
// For ErrorTypes we want to eagerly produce a hole since we know
// this is where the issue is.
if (auto *errTy = dyn_cast<ErrorType>(tyPtr)) {
return PlaceholderType::get(getASTContext(), errTy);
}
return std::nullopt;
});
addContextualConversionConstraint(expr, convertType, ctp,
convertTypeLocator);
}
// For an initialization target, generate constraints for the pattern.
if (target.isForInitialization() &&
generateInitPatternConstraints(*this, target, expr)) {
return true;
}
if (isDebugMode()) {
auto &log = llvm::errs();
log << "\n---Initial constraints for the given expression---\n";
print(log, expr);
log << "\n";
print(log);
log << "\n";
}
return false;
}
switch (target.kind) {
case SyntacticElementTarget::Kind::expression:
llvm_unreachable("Handled above");
case SyntacticElementTarget::Kind::closure:
case SyntacticElementTarget::Kind::caseLabelItem:
case SyntacticElementTarget::Kind::function:
case SyntacticElementTarget::Kind::stmtCondition:
llvm_unreachable("Handled separately");
case SyntacticElementTarget::Kind::patternBinding: {
auto patternBinding = target.getAsPatternBinding();
auto dc = target.getDeclContext();
bool hadError = false;
/// Generate constraints for each pattern binding entry
for (unsigned index : range(patternBinding->getNumPatternEntries())) {
auto *pattern = TypeChecker::resolvePattern(
patternBinding->getPattern(index), dc, /*isStmtCondition=*/true);
if (!pattern)
return true;
// Reset binding to point to the resolved pattern. This is required
// before calling `forPatternBindingDecl`.
patternBinding->setPattern(index, pattern);
auto contextualPattern =
ContextualPattern::forPatternBindingDecl(patternBinding, index);
Type patternType = TypeChecker::typeCheckPattern(contextualPattern);
auto *init = patternBinding->getInit(index);
if (!init && patternBinding->isDefaultInitializable(index) &&
pattern->hasStorage()) {
init = TypeChecker::buildDefaultInitializer(patternType);
}
auto target = init ? SyntacticElementTarget::forInitialization(
init, patternType, patternBinding, index,
/*bindPatternVarsOneWay=*/true)
: SyntacticElementTarget::forUninitializedVar(
patternBinding, index, patternType);
if (generateConstraints(target)) {
hadError = true;
continue;
}
// Keep track of this binding entry.
setTargetFor({patternBinding, index}, target);
}
return hadError;
}
case SyntacticElementTarget::Kind::uninitializedVar: {
if (auto *wrappedVar = target.getAsUninitializedWrappedVar()) {
auto propertyType = wrappedVar->getTypeInContext();
if (propertyType->hasError())
return true;
return generateWrappedPropertyTypeConstraints(
wrappedVar, /*initializerType=*/Type(), propertyType);
} else {
auto pattern = target.getAsUninitializedVar();
auto locator = getConstraintLocator(
pattern, LocatorPathElt::ContextualType(CTP_Initialization));
// Generate constraints to bind all of the internal declarations
// and verify the pattern.
Type patternType = generateConstraints(
pattern, locator, /*shouldBindPatternVarsOneWay*/ true,
target.getPatternBindingOfUninitializedVar(),
target.getIndexOfUninitializedVar());
return !patternType;
}
}
case SyntacticElementTarget::Kind::forEachPreamble: {
// For a for-each statement, generate constraints for the pattern, where
// clause, and sequence traversal.
auto resultTarget = generateForEachPreambleConstraints(*this, target);
if (!resultTarget)
return true;
target = *resultTarget;
return false;
}
}
}
Expr *ConstraintSystem::generateConstraints(Expr *expr, DeclContext *dc) {
InputExprs.insert(expr);
return generateConstraintsFor(*this, expr, dc);
}
Type ConstraintSystem::generateConstraints(
Pattern *pattern, ConstraintLocatorBuilder locator,
bool bindPatternVarsOneWay, PatternBindingDecl *patternBinding,
unsigned patternIndex) {
ConstraintGenerator cg(*this, nullptr);
auto ty = cg.getTypeForPattern(pattern, locator, bindPatternVarsOneWay,
patternBinding, patternIndex);
assert(ty);
// Gather the ExprPatterns, and form a conjunction for their expressions.
SmallVector<ExprPattern *, 4> exprPatterns;
pattern->forEachNode([&](Pattern *P) {
if (auto *EP = dyn_cast<ExprPattern>(P))
exprPatterns.push_back(EP);
});
if (!exprPatterns.empty())
generateConstraints(exprPatterns, getConstraintLocator(pattern));
return ty;
}
bool ConstraintSystem::generateConstraints(StmtCondition condition,
DeclContext *dc) {
// FIXME: This should be folded into constraint generation for conditions.
auto boolDecl = getASTContext().getBoolDecl();
if (!boolDecl) {
return true;
}
Type boolTy = boolDecl->getDeclaredInterfaceType();
for (auto &condElement : condition) {
switch (condElement.getKind()) {
case StmtConditionElement::CK_Availability:
// Nothing to do here.
continue;
case StmtConditionElement::CK_HasSymbol: {
Expr *symbolExpr = condElement.getHasSymbolInfo()->getSymbolExpr();
auto target = SyntacticElementTarget(symbolExpr, dc, CTP_Unused, Type(),
/*isDiscarded=*/false);
if (generateConstraints(target))
return true;
setTargetFor(&condElement, target);
continue;
}
case StmtConditionElement::CK_Boolean: {
Expr *condExpr = condElement.getBoolean();
auto target = SyntacticElementTarget(condExpr, dc, CTP_Condition, boolTy,
/*isDiscarded=*/false);
if (generateConstraints(target, FreeTypeVariableBinding::Disallow))
return true;
setTargetFor(&condElement, target);
continue;
}
case StmtConditionElement::CK_PatternBinding: {
auto *pattern = TypeChecker::resolvePattern(
condElement.getPattern(), dc, /*isStmtCondition*/true);
if (!pattern)
return true;
auto target = SyntacticElementTarget::forInitialization(
condElement.getInitializer(), dc, Type(), pattern,
/*bindPatternVarsOneWay=*/true);
if (generateConstraints(target, FreeTypeVariableBinding::Disallow))
return true;
setTargetFor(&condElement, target);
continue;
}
}
}
return false;
}
void ConstraintSystem::applyPropertyWrapper(
Expr *anchor, AppliedPropertyWrapper applied,
PreparedOverloadBuilder *preparedOverload) {
if (preparedOverload) {
ASSERT(PreparingOverload);
preparedOverload->appliedPropertyWrapper(applied);
return;
}
ASSERT(!PreparingOverload);
appliedPropertyWrappers[anchor].push_back(applied);
if (solverState)
recordChange(SolverTrail::Change::AppliedPropertyWrapper(anchor));
}
void ConstraintSystem::removePropertyWrapper(Expr *anchor) {
auto found = appliedPropertyWrappers.find(anchor);
ASSERT(found != appliedPropertyWrappers.end());
auto &wrappers = found->second;
ASSERT(!wrappers.empty());
wrappers.pop_back();
if (wrappers.empty()) {
bool erased = appliedPropertyWrappers.erase(anchor);
ASSERT(erased);
}
}
ConstraintSystem::TypeMatchResult
ConstraintSystem::applyPropertyWrapperToParameter(
Type wrapperType,
Type paramType,
ParamDecl *param,
Identifier argLabel,
ConstraintKind matchKind,
ConstraintLocator *locator,
ConstraintLocator *calleeLocator,
PreparedOverloadBuilder *preparedOverload) {
Expr *anchor = getAsExpr(calleeLocator->getAnchor());
auto recordPropertyWrapperFix = [&](ConstraintFix *fix) -> TypeMatchResult {
if (!shouldAttemptFixes())
return getTypeMatchFailure(locator);
recordAnyTypeVarAsPotentialHole(paramType);
if (recordFix(fix, /*impact=*/1, preparedOverload))
return getTypeMatchFailure(locator);
return getTypeMatchSuccess();
};
// Incorrect use of projected value argument
if (argLabel.hasDollarPrefix() &&
(!param || !param->hasExternalPropertyWrapper())) {
auto *loc = getConstraintLocator(locator);
auto *fix =
RemoveProjectedValueArgument::create(*this, wrapperType, param, loc);
return recordPropertyWrapperFix(fix);
}
// Missing wrapped value initializer
auto wrapperInfo = param->getAttachedPropertyWrapperTypeInfo(0);
if (!argLabel.hasDollarPrefix() && !wrapperInfo.wrappedValueInit &&
param->hasExternalPropertyWrapper()) {
auto *loc = getConstraintLocator(locator);
auto *fix = UsePropertyWrapper::create(
*this, param, /*usingProjection=*/true, paramType, wrapperType, loc);
return recordPropertyWrapperFix(fix);
}
if (argLabel.hasDollarPrefix()) {
Type projectionType = computeProjectedValueType(param, wrapperType);
addConstraint(matchKind, paramType, projectionType, locator,
/*isFavored=*/false,
preparedOverload);
if (param->hasImplicitPropertyWrapper()) {
auto wrappedValueType = getType(param->getPropertyWrapperWrappedValueVar());
addConstraint(ConstraintKind::PropertyWrapper,
projectionType, wrappedValueType,
getConstraintLocator(param),
/*isFavored=*/false,
preparedOverload);
setType(param->getPropertyWrapperProjectionVar(), projectionType);
}
applyPropertyWrapper(anchor,
{ wrapperType, PropertyWrapperInitKind::ProjectedValue },
preparedOverload);
} else if (param->hasExternalPropertyWrapper()) {
Type wrappedValueType = computeWrappedValueType(param, wrapperType);
addConstraint(matchKind, paramType, wrappedValueType,
locator,
/*isFavored=*/false,
preparedOverload);
setType(param->getPropertyWrapperWrappedValueVar(), wrappedValueType,
preparedOverload);
applyPropertyWrapper(anchor,
{ wrapperType, PropertyWrapperInitKind::WrappedValue },
preparedOverload);
} else {
return getTypeMatchFailure(locator);
}
return getTypeMatchSuccess();
}
void ConstraintSystem::optimizeConstraints(Expr *e) {
if (!performanceHacksEnabled())
return;
SmallVector<Expr *, 16> linkedExprs;
// Collect any linked expressions.
LinkedExprCollector collector(linkedExprs);
e->walk(collector);
// Favor types, as appropriate.
for (auto linkedExpr : linkedExprs) {
computeFavoredTypeForExpr(linkedExpr, *this);
}
// Optimize the constraints.
ConstraintOptimizer optimizer(*this);
e->walk(optimizer);
}
struct ResolvedMemberResult::Implementation {
llvm::SmallVector<ValueDecl*, 4> AllDecls;
unsigned ViableStartIdx;
std::optional<unsigned> BestIdx;
};
ResolvedMemberResult::ResolvedMemberResult(): Impl(new Implementation()) {}
ResolvedMemberResult::~ResolvedMemberResult() { delete Impl; }
ResolvedMemberResult::operator bool() const {
return !Impl->AllDecls.empty();
}
bool ResolvedMemberResult::
hasBestOverload() const { return Impl->BestIdx.has_value(); }
ValueDecl* ResolvedMemberResult::
getBestOverload() const { return Impl->AllDecls[Impl->BestIdx.value()]; }
ArrayRef<ValueDecl*> ResolvedMemberResult::
getMemberDecls(InterestedMemberKind Kind) {
auto Result = llvm::ArrayRef(Impl->AllDecls);
switch (Kind) {
case InterestedMemberKind::Viable:
return Result.slice(Impl->ViableStartIdx);
case InterestedMemberKind::Unviable:
return Result.slice(0, Impl->ViableStartIdx);
case InterestedMemberKind::All:
return Result;
}
llvm_unreachable("unhandled kind");
}
ResolvedMemberResult swift::resolveValueMember(DeclContext &DC, Type BaseTy,
DeclName Name) {
ResolvedMemberResult Result;
ConstraintSystem CS(&DC, std::nullopt);
// Look up all members of BaseTy with the given Name.
MemberLookupResult LookupResult =
CS.performMemberLookup(ConstraintKind::ValueMember, DeclNameRef(Name),
BaseTy, FunctionRefInfo::singleBaseNameApply(),
CS.getConstraintLocator({}), false);
// Keep track of all the unviable members.
for (auto Can : LookupResult.UnviableCandidates)
Result.Impl->AllDecls.push_back(Can.getDecl());
// Keep track of the start of viable choices.
Result.Impl->ViableStartIdx = Result.Impl->AllDecls.size();
// If no viable members, we are done.
if (LookupResult.ViableCandidates.empty())
return Result;
// If there's only one viable member, that is the best one.
if (LookupResult.ViableCandidates.size() == 1) {
Result.Impl->BestIdx = Result.Impl->AllDecls.size();
Result.Impl->AllDecls.push_back(LookupResult.ViableCandidates[0].getDecl());
return Result;
}
// Try to figure out the best overload.
ConstraintLocator *Locator = CS.getConstraintLocator({});
TypeVariableType *TV = CS.createTypeVariable(Locator,
TVO_CanBindToLValue |
TVO_CanBindToNoEscape);
CS.addOverloadSet(TV, LookupResult.ViableCandidates, &DC, Locator);
std::optional<Solution> OpSolution = CS.solveSingle();
ValueDecl *Selected = nullptr;
if (OpSolution.has_value()) {
Selected = OpSolution.value().overloadChoices[Locator].choice.getDecl();
}
for (OverloadChoice& Choice : LookupResult.ViableCandidates) {
ValueDecl *VD = Choice.getDecl();
// If this VD is the best overload, keep track of its index.
if (VD == Selected)
Result.Impl->BestIdx = Result.Impl->AllDecls.size();
Result.Impl->AllDecls.push_back(VD);
}
return Result;
}
Reference in New Issue View Git Blame Copy Permalink