Google Git
Sign in
fuchsia / third_party / swift / 9dbd3163c4deab7c72db6a9d6e59c75407aa5dbc / . / lib / Sema / CSSimplify.cpp
blob: c77266c7ed7d7634405b0b0e94405e688eeb6ee2 [file] [log] [blame]
//===--- CSSimplify.cpp - Constraint Simplification -----------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// This file implements simplifications of constraints within the constraint
// system.
//
//===----------------------------------------------------------------------===//
#include "ConstraintSystem.h"
#include "swift/Basic/StringExtras.h"
#include "swift/ClangImporter/ClangModule.h"
using namespace swift;
using namespace constraints;
MatchCallArgumentListener::~MatchCallArgumentListener() { }
void MatchCallArgumentListener::extraArgument(unsigned argIdx) { }
void MatchCallArgumentListener::missingArgument(unsigned paramIdx) { }
void MatchCallArgumentListener::outOfOrderArgument(unsigned argIdx,
unsigned prevArgIdx) {
}
bool MatchCallArgumentListener::relabelArguments(ArrayRef<Identifier> newNames){
return true;
}
/// Produce a score (smaller is better) comparing a parameter name and
/// potentially-typo'd argument name.
///
/// \param paramName The name of the parameter.
/// \param argName The name of the argument.
/// \param maxScore The maximum score permitted by this comparison, or
/// 0 if there is no limit.
///
/// \returns the score, if it is good enough to even consider this a match.
/// Otherwise, an empty optional.
///
static Optional<unsigned> scoreParamAndArgNameTypo(StringRef paramName,
StringRef argName,
unsigned maxScore) {
using namespace camel_case;
// Compute the edit distance.
unsigned dist = argName.edit_distance(paramName, /*AllowReplacements=*/true,
/*MaxEditDistance=*/maxScore);
// If the edit distance would be too long, we're done.
if (maxScore != 0 && dist > maxScore)
return None;
// The distance can be zero due to the "with" transformation above.
if (dist == 0)
return 1;
// Only allow about one typo for every two properly-typed characters, which
// prevents completely-wacky suggestions in many cases.
if (dist > (argName.size() + 1) / 3)
return None;
return dist;
}
SmallVector<CallArgParam, 4> constraints::decomposeArgParamType(Type type) {
SmallVector<CallArgParam, 4> result;
switch (type->getKind()) {
case TypeKind::Tuple:
for (const auto &elt : cast<TupleType>(type.getPointer())->getElements()) {
CallArgParam argParam;
argParam.Ty = elt.isVararg() ? elt.getVarargBaseTy() : elt.getType();
argParam.Label = elt.getName();
argParam.HasDefaultArgument
= elt.getDefaultArgKind() != DefaultArgumentKind::None;
argParam.Variadic = elt.isVararg();
result.push_back(argParam);
}
break;
case TypeKind::Paren: {
CallArgParam argParam;
argParam.Ty = cast<ParenType>(type.getPointer())->getUnderlyingType();
result.push_back(argParam);
break;
}
default: {
CallArgParam argParam;
argParam.Ty = type;
result.push_back(argParam);
break;
}
}
return result;
}
/// Turn a param list into a symbolic and printable representation that does not
/// include the types, something like (_:, b:, c:)
std::string constraints::getParamListAsString(ArrayRef<CallArgParam> params){
std::string result = "(";
bool isFirst = true;
for (auto &param : params) {
if (isFirst)
isFirst = false;
else
result += ", ";
if (param.hasLabel())
result += param.Label.str();
else
result += "_";
result += ":";
}
result += ')';
return result;
}
bool constraints::
matchCallArguments(ArrayRef<CallArgParam> args,
ArrayRef<CallArgParam> params,
bool hasTrailingClosure,
bool allowFixes,
MatchCallArgumentListener &listener,
SmallVectorImpl<ParamBinding> &parameterBindings) {
// Keep track of the parameter we're matching and what argument indices
// got bound to each parameter.
unsigned paramIdx, numParams = params.size();
parameterBindings.clear();
parameterBindings.resize(numParams);
// Keep track of which arguments we have claimed from the argument tuple.
unsigned nextArgIdx = 0, numArgs = args.size();
SmallVector<bool, 4> claimedArgs(numArgs, false);
SmallVector<Identifier, 4> actualArgNames;
unsigned numClaimedArgs = 0;
// Indicates whether any of the arguments are potentially out-of-order,
// requiring further checking at the end.
bool potentiallyOutOfOrder = false;
// Local function that claims the argument at \c argNumber, returning the
// index of the claimed argument. This is primarily a helper for
// \c claimNextNamed.
auto claim = [&](Identifier expectedName, unsigned argNumber,
bool ignoreNameClash = false) -> unsigned {
// Make sure we can claim this argument.
assert(argNumber != numArgs && "Must have a valid index to claim");
assert(!claimedArgs[argNumber] && "Argument already claimed");
if (!actualArgNames.empty()) {
// We're recording argument names; record this one.
actualArgNames[argNumber] = expectedName;
} else if (args[argNumber].Label != expectedName && !ignoreNameClash) {
// We have an argument name mismatch. Start recording argument names.
actualArgNames.resize(numArgs);
// Figure out previous argument names from the parameter bindings.
for (unsigned i = 0; i != numParams; ++i) {
const auto &param = params[i];
bool firstArg = true;
for (auto argIdx : parameterBindings[i]) {
actualArgNames[argIdx] = firstArg ? param.Label : Identifier();
firstArg = false;
}
}
// Record this argument name.
actualArgNames[argNumber] = expectedName;
}
claimedArgs[argNumber] = true;
++numClaimedArgs;
return argNumber;
};
// Local function that skips over any claimed arguments.
auto skipClaimedArgs = [&]() {
while (nextArgIdx != numArgs && claimedArgs[nextArgIdx])
++nextArgIdx;
};
// Local function that retrieves the next unclaimed argument with the given
// name (which may be empty). This routine claims the argument.
auto claimNextNamed
= [&](Identifier name, bool ignoreNameMismatch) -> Optional<unsigned> {
// Skip over any claimed arguments.
skipClaimedArgs();
// If we've claimed all of the arguments, there's nothing more to do.
if (numClaimedArgs == numArgs)
return None;
// When the expected name is empty, we claim the next argument if it has
// no name.
if (name.empty()) {
// Nothing to claim.
if (nextArgIdx == numArgs ||
claimedArgs[nextArgIdx] ||
(args[nextArgIdx].hasLabel() && !ignoreNameMismatch))
return None;
return claim(name, nextArgIdx);
}
// If the name matches, claim this argument.
if (nextArgIdx != numArgs &&
(ignoreNameMismatch || args[nextArgIdx].Label == name)) {
return claim(name, nextArgIdx);
}
// The name didn't match. Go hunting for an unclaimed argument whose name
// does match.
Optional<unsigned> claimedWithSameName;
for (unsigned i = nextArgIdx; i != numArgs; ++i) {
// Skip arguments where the name doesn't match.
if (args[i].Label != name)
continue;
// Skip claimed arguments.
if (claimedArgs[i]) {
// Note that we have already claimed an argument with the same name.
if (!claimedWithSameName)
claimedWithSameName = i;
continue;
}
// We found a match. If the match wasn't the next one, we have
// potentially out of order arguments.
if (i != nextArgIdx)
potentiallyOutOfOrder = true;
// Claim it.
return claim(name, i);
}
// If we're not supposed to attempt any fixes, we're done.
if (!allowFixes)
return None;
// Several things could have gone wrong here, and we'll check for each
// of them at some point:
// - The keyword argument might be redundant, in which case we can point
// out the issue.
// - The argument might be unnamed, in which case we try to fix the
// problem by adding the name.
// - The keyword argument might be a typo for an actual argument name, in
// which case we should find the closest match to correct to.
// Redundant keyword arguments.
if (claimedWithSameName) {
// FIXME: We can provide better diagnostics here.
return None;
}
// Missing a keyword argument name.
if (nextArgIdx != numArgs && !args[nextArgIdx].hasLabel()) {
// Claim the next argument.
return claim(name, nextArgIdx);
}
// Typo correction is handled in a later pass.
return None;
};
// Local function that attempts to bind the given parameter to arguments in
// the list.
bool haveUnfulfilledParams = false;
auto bindNextParameter = [&](bool ignoreNameMismatch) {
const auto &param = params[paramIdx];
// Handle variadic parameters.
if (param.Variadic) {
// Claim the next argument with the name of this parameter.
auto claimed = claimNextNamed(param.Label, ignoreNameMismatch);
// If there was no such argument, leave the argument unf
if (!claimed) {
haveUnfulfilledParams = true;
return;
}
// Record the first argument for the variadic.
parameterBindings[paramIdx].push_back(*claimed);
// Claim any additional unnamed arguments.
while ((claimed = claimNextNamed(Identifier(), false))) {
parameterBindings[paramIdx].push_back(*claimed);
}
skipClaimedArgs();
return;
}
// Try to claim an argument for this parameter.
if (auto claimed = claimNextNamed(param.Label, ignoreNameMismatch)) {
parameterBindings[paramIdx].push_back(*claimed);
skipClaimedArgs();
return;
}
// There was no argument to claim. Leave the argument unfulfilled.
haveUnfulfilledParams = true;
};
// If we have a trailing closure, it maps to the last parameter.
if (hasTrailingClosure && numParams > 0) {
claimedArgs[numArgs-1] = true;
++numClaimedArgs;
parameterBindings[numParams-1].push_back(numArgs-1);
}
// Mark through the parameters, binding them to their arguments.
for (paramIdx = 0; paramIdx != numParams; ++paramIdx) {
if (parameterBindings[paramIdx].empty())
bindNextParameter(false);
}
// If we have any unclaimed arguments, complain about those.
if (numClaimedArgs != numArgs) {
// Find all of the named, unclaimed arguments.
llvm::SmallVector<unsigned, 4> unclaimedNamedArgs;
for (nextArgIdx = 0; skipClaimedArgs(), nextArgIdx != numArgs;
++nextArgIdx) {
if (args[nextArgIdx].hasLabel())
unclaimedNamedArgs.push_back(nextArgIdx);
}
if (!unclaimedNamedArgs.empty()) {
// Find all of the named, unfulfilled parameters.
llvm::SmallVector<unsigned, 4> unfulfilledNamedParams;
bool hasUnfulfilledUnnamedParams = false;
for (paramIdx = 0; paramIdx != numParams; ++paramIdx ) {
if (parameterBindings[paramIdx].empty()) {
if (params[paramIdx].hasLabel())
unfulfilledNamedParams.push_back(paramIdx);
else
hasUnfulfilledUnnamedParams = true;
}
}
if (!unfulfilledNamedParams.empty()) {
// Use typo correction to find the best matches.
// FIXME: There is undoubtedly a good dynamic-programming algorithm
// to find the best assignment here.
for (auto argIdx : unclaimedNamedArgs) {
auto argName = args[argIdx].Label;
// Find the closest matching unfulfilled named parameter.
unsigned bestScore = 0;
unsigned best = 0;
for (unsigned i = 0, n = unfulfilledNamedParams.size(); i != n; ++i) {
unsigned param = unfulfilledNamedParams[i];
auto paramName = params[param].Label;
if (auto score = scoreParamAndArgNameTypo(paramName.str(),
argName.str(),
bestScore)) {
if (*score < bestScore || bestScore == 0) {
bestScore = *score;
best = i;
}
}
}
// If we found a parameter to fulfill, do it.
if (bestScore > 0) {
// Bind this parameter to the argument.
nextArgIdx = argIdx;
paramIdx = unfulfilledNamedParams[best];
bindNextParameter(true);
// Erase this parameter from the list of unfulfilled named
// parameters, so we don't try to fulfill it again.
unfulfilledNamedParams.erase(unfulfilledNamedParams.begin() + best);
if (unfulfilledNamedParams.empty())
break;
}
}
// Update haveUnfulfilledParams, because we may have fulfilled some
// parameters above.
haveUnfulfilledParams = hasUnfulfilledUnnamedParams ||
!unfulfilledNamedParams.empty();
}
}
// Find all of the unfulfilled parameters, and match them up
// semi-positionally.
if (numClaimedArgs != numArgs) {
// Restart at the first argument/parameter.
nextArgIdx = 0;
skipClaimedArgs();
haveUnfulfilledParams = false;
for (paramIdx = 0; paramIdx != numParams; ++paramIdx) {
// Skip fulfilled parameters.
if (!parameterBindings[paramIdx].empty())
continue;
bindNextParameter(true);
}
}
// If we still haven't claimed all of the arguments, fail.
if (numClaimedArgs != numArgs) {
nextArgIdx = 0;
skipClaimedArgs();
listener.extraArgument(nextArgIdx);
return true;
}
// FIXME: If we had the actual parameters and knew the body names, those
// matches would be best.
potentiallyOutOfOrder = true;
}
// If we have any unfulfilled parameters, check them now.
if (haveUnfulfilledParams) {
for (paramIdx = 0; paramIdx != numParams; ++paramIdx) {
// If we have a binding for this parameter, we're done.
if (!parameterBindings[paramIdx].empty())
continue;
const auto &param = params[paramIdx];
// Variadic parameters can be unfulfilled.
if (param.Variadic)
continue;
// Parameters with defaults can be unfulfilled.
if (param.HasDefaultArgument)
continue;
listener.missingArgument(paramIdx);
return true;
}
}
// If any arguments were provided out-of-order, check whether we have
// violated any of the reordering rules.
if (potentiallyOutOfOrder) {
// Build a mapping from arguments to parameters.
SmallVector<unsigned, 4> argumentBindings(numArgs);
for(paramIdx = 0; paramIdx != numParams; ++paramIdx) {
for (auto argIdx : parameterBindings[paramIdx])
argumentBindings[argIdx] = paramIdx;
}
// Walk through the arguments, determining if any were bound to parameters
// out-of-order where it is not permitted.
unsigned prevParamIdx = argumentBindings[0];
for (unsigned argIdx = 1; argIdx != numArgs; ++argIdx) {
unsigned paramIdx = argumentBindings[argIdx];
// If this argument binds to the same parameter as the previous one or to
// a later parameter, just update the parameter index.
if (paramIdx >= prevParamIdx) {
prevParamIdx = paramIdx;
continue;
}
// The argument binds to a parameter that comes earlier than the
// previous argument. This is fine so long as this parameter and all of
// those parameters up to (and including) the previously-bound parameter
// are either variadic or have a default argument.
for (unsigned i = paramIdx; i != prevParamIdx + 1; ++i) {
const auto &param = params[i];
if (param.Variadic || param.HasDefaultArgument)
continue;
unsigned prevArgIdx = parameterBindings[prevParamIdx].front();
listener.outOfOrderArgument(argIdx, prevArgIdx);
return true;
}
}
}
// If no arguments were renamed, the call arguments match up with the
// parameters.
if (actualArgNames.empty())
return false;
// The arguments were relabeled; notify the listener.
return listener.relabelArguments(actualArgNames);
}
// Match the argument of a call to the parameter.
static ConstraintSystem::SolutionKind
matchCallArguments(ConstraintSystem &cs, TypeMatchKind kind,
Type argType, Type paramType,
ConstraintLocatorBuilder locator) {
/// Listener used to produce failures if they should be produced.
class Listener : public MatchCallArgumentListener {
ConstraintSystem &CS;
Type ArgType;
Type ParamType;
ConstraintLocatorBuilder &Locator;
public:
Listener(ConstraintSystem &cs, Type argType, Type paramType,
ConstraintLocatorBuilder &locator)
: CS(cs), ArgType(argType), ParamType(paramType), Locator(locator) { }
bool relabelArguments(ArrayRef<Identifier> newNames) override {
if (!CS.shouldAttemptFixes()) {
// FIXME: record why this failed. We have renaming.
return true;
}
// Add a fix for the name. This is only responsible for recording the fix.
auto result = CS.simplifyFixConstraint(
Fix::getRelabelTuple(CS, FixKind::RelabelCallTuple,
newNames),
ArgType, ParamType,
TypeMatchKind::ArgumentTupleConversion,
ConstraintSystem::TMF_None,
Locator);
return result != ConstraintSystem::SolutionKind::Solved;
}
};
// In the empty existential parameter case, we don't need to decompose the
// arguments.
if (paramType->isEmptyExistentialComposition()) {
if (argType->is<InOutType>()) {
return ConstraintSystem::SolutionKind::Error;
}
return ConstraintSystem::SolutionKind::Solved;
}
// Extract the arguments.
auto args = decomposeArgParamType(argType);
// Extract the parameters.
auto params = decomposeArgParamType(paramType);
// Match up the call arguments to the parameters.
Listener listener(cs, argType, paramType, locator);
SmallVector<ParamBinding, 4> parameterBindings;
if (constraints::matchCallArguments(args, params,
hasTrailingClosure(locator),
cs.shouldAttemptFixes(), listener,
parameterBindings))
return ConstraintSystem::SolutionKind::Error;
// Check the argument types for each of the parameters.
unsigned subflags = ConstraintSystem::TMF_GenerateConstraints;
TypeMatchKind subKind;
switch (kind) {
case TypeMatchKind::ArgumentTupleConversion:
subKind = TypeMatchKind::ArgumentConversion;
break;
case TypeMatchKind::OperatorArgumentTupleConversion:
subKind = TypeMatchKind::OperatorArgumentConversion;
break;
case TypeMatchKind::Conversion:
case TypeMatchKind::ExplicitConversion:
case TypeMatchKind::OperatorArgumentConversion:
case TypeMatchKind::ArgumentConversion:
case TypeMatchKind::BindType:
case TypeMatchKind::BindParamType:
case TypeMatchKind::BindToPointerType:
case TypeMatchKind::SameType:
case TypeMatchKind::ConformsTo:
case TypeMatchKind::Subtype:
llvm_unreachable("Not a call argument constraint");
}
auto haveOneNonUserConversion =
(subKind != TypeMatchKind::OperatorArgumentConversion);
auto haveNilArgument = false;
auto nilLiteralProto = cs.TC.getProtocol(SourceLoc(),
KnownProtocolKind::
NilLiteralConvertible);
auto isNilLiteral = [&](Type t) -> bool {
if (auto tyvar = t->getAs<TypeVariableType>()) {
return tyvar->getImpl().literalConformanceProto == nilLiteralProto;
}
return false;
};
// If we're applying an operator function to a nil literal operand, we
// disallow value-to-optional conversions from taking place so as not to
// select an overly permissive overload.
auto allowOptionalConversion = [&](Type t) -> bool {
if (t->isLValueType())
t = t->getLValueOrInOutObjectType();
if (!t->getAnyOptionalObjectType().isNull())
return true;
if (isNilLiteral(t))
return true;
if (auto nt = t->getNominalOrBoundGenericNominal()) {
return nt->getName() == cs.TC.Context.Id_OptionalNilComparisonType;
}
return false;
};
// Pre-scan operator arguments for nil literals.
if (subKind == TypeMatchKind::OperatorArgumentConversion) {
for (auto arg : args) {
if (isNilLiteral(arg.Ty)) {
haveNilArgument = true;
break;
}
}
}
for (unsigned paramIdx = 0, numParams = parameterBindings.size();
paramIdx != numParams; ++paramIdx){
// Skip unfulfilled parameters. There's nothing to do for them.
if (parameterBindings[paramIdx].empty())
continue;
// Determine the parameter type.
const auto &param = params[paramIdx];
auto paramTy = param.Ty;
// Compare each of the bound arguments for this parameter.
for (auto argIdx : parameterBindings[paramIdx]) {
auto loc = locator.withPathElement(LocatorPathElt::
getApplyArgToParam(argIdx,
paramIdx));
auto argTy = args[argIdx].Ty;
if (haveNilArgument && !allowOptionalConversion(argTy)) {
subflags |= ConstraintSystem::TMF_ApplyingOperatorWithNil;
}
if (!haveOneNonUserConversion) {
subflags |= ConstraintSystem::TMF_ApplyingOperatorParameter;
}
switch (cs.matchTypes(argTy,paramTy,
subKind, subflags,
loc)) {
case ConstraintSystem::SolutionKind::Error:
return ConstraintSystem::SolutionKind::Error;
case ConstraintSystem::SolutionKind::Solved:
case ConstraintSystem::SolutionKind::Unsolved:
break;
}
}
}
return ConstraintSystem::SolutionKind::Solved;
}
ConstraintSystem::SolutionKind
ConstraintSystem::matchTupleTypes(TupleType *tuple1, TupleType *tuple2,
TypeMatchKind kind, unsigned flags,
ConstraintLocatorBuilder locator) {
unsigned subFlags = flags | TMF_GenerateConstraints;
// Equality and subtyping have fairly strict requirements on tuple matching,
// requiring element names to either match up or be disjoint.
if (kind < TypeMatchKind::Conversion) {
if (tuple1->getNumElements() != tuple2->getNumElements())
return SolutionKind::Error;
for (unsigned i = 0, n = tuple1->getNumElements(); i != n; ++i) {
const auto &elt1 = tuple1->getElement(i);
const auto &elt2 = tuple2->getElement(i);
// If the names don't match, we may have a conflict.
if (elt1.getName() != elt2.getName()) {
// Same-type requirements require exact name matches.
if (kind == TypeMatchKind::SameType)
return SolutionKind::Error;
// For subtyping constraints, just make sure that this name isn't
// used at some other position.
if (elt2.hasName() && tuple1->getNamedElementId(elt2.getName()) != -1)
return SolutionKind::Error;
}
// Variadic bit must match.
if (elt1.isVararg() != elt2.isVararg())
return SolutionKind::Error;
// Compare the element types.
switch (matchTypes(elt1.getType(), elt2.getType(), kind, subFlags,
locator.withPathElement(
LocatorPathElt::getTupleElement(i)))) {
case SolutionKind::Error:
return SolutionKind::Error;
case SolutionKind::Solved:
case SolutionKind::Unsolved:
break;
}
}
return SolutionKind::Solved;
}
assert(kind >= TypeMatchKind::Conversion);
TypeMatchKind subKind;
switch (kind) {
case TypeMatchKind::ArgumentTupleConversion:
subKind = TypeMatchKind::ArgumentConversion;
break;
case TypeMatchKind::OperatorArgumentTupleConversion:
subKind = TypeMatchKind::OperatorArgumentConversion;
break;
case TypeMatchKind::OperatorArgumentConversion:
case TypeMatchKind::ArgumentConversion:
case TypeMatchKind::ExplicitConversion:
case TypeMatchKind::Conversion:
subKind = TypeMatchKind::Conversion;
break;
case TypeMatchKind::BindType:
case TypeMatchKind::BindParamType:
case TypeMatchKind::BindToPointerType:
case TypeMatchKind::SameType:
case TypeMatchKind::Subtype:
case TypeMatchKind::ConformsTo:
llvm_unreachable("Not a conversion");
}
// Compute the element shuffles for conversions.
SmallVector<int, 16> sources;
SmallVector<unsigned, 4> variadicArguments;
if (computeTupleShuffle(tuple1, tuple2, sources, variadicArguments))
return SolutionKind::Error;
// Check each of the elements.
bool hasVariadic = false;
unsigned variadicIdx = sources.size();
for (unsigned idx2 = 0, n = sources.size(); idx2 != n; ++idx2) {
// Default-initialization always allowed for conversions.
if (sources[idx2] == TupleShuffleExpr::DefaultInitialize) {
continue;
}
// Variadic arguments handled below.
if (sources[idx2] == TupleShuffleExpr::Variadic) {
assert(!hasVariadic && "Multiple variadic parameters");
hasVariadic = true;
variadicIdx = idx2;
continue;
}
assert(sources[idx2] >= 0);
unsigned idx1 = sources[idx2];
// Match up the types.
const auto &elt1 = tuple1->getElement(idx1);
const auto &elt2 = tuple2->getElement(idx2);
switch (matchTypes(elt1.getType(), elt2.getType(), subKind, subFlags,
locator.withPathElement(
LocatorPathElt::getTupleElement(idx1)))) {
case SolutionKind::Error:
return SolutionKind::Error;
case SolutionKind::Solved:
case SolutionKind::Unsolved:
break;
}
}
// If we have variadic arguments to check, do so now.
if (hasVariadic) {
const auto &elt2 = tuple2->getElements()[variadicIdx];
auto eltType2 = elt2.getVarargBaseTy();
for (unsigned idx1 : variadicArguments) {
switch (matchTypes(tuple1->getElementType(idx1), eltType2, subKind,
subFlags,
locator.withPathElement(
LocatorPathElt::getTupleElement(idx1)))) {
case SolutionKind::Error:
return SolutionKind::Error;
case SolutionKind::Solved:
case SolutionKind::Unsolved:
break;
}
}
}
return SolutionKind::Solved;
}
ConstraintSystem::SolutionKind
ConstraintSystem::matchScalarToTupleTypes(Type type1, TupleType *tuple2,
TypeMatchKind kind, unsigned flags,
ConstraintLocatorBuilder locator) {
int scalarFieldIdx = tuple2->getElementForScalarInit();
assert(scalarFieldIdx >= 0 && "Invalid tuple for scalar-to-tuple");
const auto &elt = tuple2->getElement(scalarFieldIdx);
auto scalarFieldTy = elt.isVararg()? elt.getVarargBaseTy() : elt.getType();
return matchTypes(type1, scalarFieldTy, kind, flags,
locator.withPathElement(ConstraintLocator::ScalarToTuple));
}
ConstraintSystem::SolutionKind
ConstraintSystem::matchTupleToScalarTypes(TupleType *tuple1, Type type2,
TypeMatchKind kind, unsigned flags,
ConstraintLocatorBuilder locator) {
assert(tuple1->getNumElements() == 1 && "Wrong number of elements");
assert(!tuple1->getElement(0).isVararg() && "Should not be variadic");
return matchTypes(tuple1->getElementType(0),
type2, kind, flags,
locator.withPathElement(
LocatorPathElt::getTupleElement(0)));
}
// Returns 'false' (i.e. no error) if it is legal to match functions with the
// corresponding function type representations and the given match kind.
static bool matchFunctionRepresentations(FunctionTypeRepresentation rep1,
FunctionTypeRepresentation rep2,
TypeMatchKind kind) {
switch (kind) {
case TypeMatchKind::BindType:
case TypeMatchKind::BindParamType:
case TypeMatchKind::BindToPointerType:
case TypeMatchKind::SameType:
return rep1 != rep2;
case TypeMatchKind::ConformsTo:
llvm_unreachable("Not sure if we can end up here");
case TypeMatchKind::Subtype:
case TypeMatchKind::Conversion:
case TypeMatchKind::ExplicitConversion:
case TypeMatchKind::ArgumentConversion:
case TypeMatchKind::ArgumentTupleConversion:
case TypeMatchKind::OperatorArgumentTupleConversion:
case TypeMatchKind::OperatorArgumentConversion:
return false;
}
}
ConstraintSystem::SolutionKind
ConstraintSystem::matchFunctionTypes(FunctionType *func1, FunctionType *func2,
TypeMatchKind kind, unsigned flags,
ConstraintLocatorBuilder locator) {
// An @autoclosure function type can be a subtype of a
// non-@autoclosure function type.
if (func1->isAutoClosure() != func2->isAutoClosure() &&
(func2->isAutoClosure() || kind < TypeMatchKind::Subtype))
return SolutionKind::Error;
// A non-throwing function can be a subtype of a throwing function.
if (func1->throws() != func2->throws()) {
// Cannot drop 'throws'.
if (func1->throws() || (func2->throws() && kind < TypeMatchKind::Subtype))
return SolutionKind::Error;
}
// A @noreturn function type can be a subtype of a non-@noreturn function
// type.
if (func1->isNoReturn() != func2->isNoReturn() &&
(func2->isNoReturn() || kind < TypeMatchKind::SameType))
return SolutionKind::Error;
// A non-@noescape function type can be a subtype of a @noescape function
// type.
if (func1->isNoEscape() != func2->isNoEscape() &&
(func1->isNoEscape() || kind < TypeMatchKind::Subtype))
return SolutionKind::Error;
if (matchFunctionRepresentations(func1->getExtInfo().getRepresentation(),
func2->getExtInfo().getRepresentation(),
kind)) {
return SolutionKind::Error;
}
// Determine how we match up the input/result types.
TypeMatchKind subKind;
switch (kind) {
case TypeMatchKind::BindType:
case TypeMatchKind::BindParamType:
case TypeMatchKind::BindToPointerType:
case TypeMatchKind::SameType:
subKind = kind;
break;
case TypeMatchKind::ConformsTo:
llvm_unreachable("Not sure if we can end up here");
case TypeMatchKind::Subtype:
case TypeMatchKind::Conversion:
case TypeMatchKind::ExplicitConversion:
case TypeMatchKind::ArgumentConversion:
case TypeMatchKind::ArgumentTupleConversion:
case TypeMatchKind::OperatorArgumentTupleConversion:
case TypeMatchKind::OperatorArgumentConversion:
subKind = TypeMatchKind::Subtype;
break;
}
unsigned subFlags = flags | TMF_GenerateConstraints;
// Input types can be contravariant (or equal).
SolutionKind result = matchTypes(func2->getInput(), func1->getInput(),
subKind, subFlags,
locator.withPathElement(
ConstraintLocator::FunctionArgument));
if (result == SolutionKind::Error)
return SolutionKind::Error;
// Result type can be covariant (or equal).
switch (matchTypes(func1->getResult(), func2->getResult(), subKind,
subFlags,
locator.withPathElement(
ConstraintLocator::FunctionResult))) {
case SolutionKind::Error:
return SolutionKind::Error;
case SolutionKind::Solved:
result = SolutionKind::Solved;
break;
case SolutionKind::Unsolved:
result = SolutionKind::Unsolved;
break;
}
return result;
}
ConstraintSystem::SolutionKind
ConstraintSystem::matchSuperclassTypes(Type type1, Type type2,
TypeMatchKind kind, unsigned flags,
ConstraintLocatorBuilder locator) {
auto classDecl2 = type2->getClassOrBoundGenericClass();
bool done = false;
for (auto super1 = TC.getSuperClassOf(type1);
!done && super1;
super1 = TC.getSuperClassOf(super1)) {
if (super1->getClassOrBoundGenericClass() != classDecl2)
continue;
return matchTypes(super1, type2, TypeMatchKind::SameType,
TMF_GenerateConstraints, locator);
}
return SolutionKind::Error;
}
ConstraintSystem::SolutionKind
ConstraintSystem::matchDeepEqualityTypes(Type type1, Type type2,
ConstraintLocatorBuilder locator) {
// Handle nominal types that are not directly generic.
if (auto nominal1 = type1->getAs<NominalType>()) {
auto nominal2 = type2->castTo<NominalType>();
assert((bool)nominal1->getParent() == (bool)nominal2->getParent() &&
"Mismatched parents of nominal types");
if (!nominal1->getParent())
return SolutionKind::Solved;
// Match up the parents, exactly.
return matchTypes(nominal1->getParent(), nominal2->getParent(),
TypeMatchKind::SameType, TMF_GenerateConstraints,
locator.withPathElement(ConstraintLocator::ParentType));
}
auto bound1 = type1->castTo<BoundGenericType>();
auto bound2 = type2->castTo<BoundGenericType>();
// Match up the parents, exactly, if there are parents.
assert((bool)bound1->getParent() == (bool)bound2->getParent() &&
"Mismatched parents of bound generics");
if (bound1->getParent()) {
switch (matchTypes(bound1->getParent(), bound2->getParent(),
TypeMatchKind::SameType, TMF_GenerateConstraints,
locator.withPathElement(ConstraintLocator::ParentType))){
case SolutionKind::Error:
return SolutionKind::Error;
case SolutionKind::Solved:
case SolutionKind::Unsolved:
break;
}
}
// Match up the generic arguments, exactly.
auto args1 = bound1->getGenericArgs();
auto args2 = bound2->getGenericArgs();
if (args1.size() != args2.size()) {
return SolutionKind::Error;
}
for (unsigned i = 0, n = args1.size(); i != n; ++i) {
switch (matchTypes(args1[i], args2[i], TypeMatchKind::SameType,
TMF_GenerateConstraints,
locator.withPathElement(
LocatorPathElt::getGenericArgument(i)))) {
case SolutionKind::Error:
return SolutionKind::Error;
case SolutionKind::Solved:
case SolutionKind::Unsolved:
break;
}
}
return SolutionKind::Solved;
}
ConstraintSystem::SolutionKind
ConstraintSystem::matchExistentialTypes(Type type1, Type type2,
ConstraintKind kind, unsigned flags,
ConstraintLocatorBuilder locator) {
if (type1->is<InOutType>()) {
return SolutionKind::Error;
}
SmallVector<ProtocolDecl *, 4> protocols;
type2->getAnyExistentialTypeProtocols(protocols);
for (auto proto : protocols) {
switch (simplifyConformsToConstraint(type1, proto, kind, locator, flags)) {
case SolutionKind::Solved:
break;
case SolutionKind::Unsolved:
// Add the constraint.
addConstraint(kind, type1, proto->getDeclaredType(),
getConstraintLocator(locator));
break;
case SolutionKind::Error:
return SolutionKind::Error;
}
}
return SolutionKind::Solved;
}
/// \brief Map a type-matching kind to a constraint kind.
static ConstraintKind getConstraintKind(TypeMatchKind kind) {
switch (kind) {
case TypeMatchKind::BindType:
case TypeMatchKind::BindToPointerType:
return ConstraintKind::Bind;
case TypeMatchKind::BindParamType:
return ConstraintKind::BindParam;
case TypeMatchKind::SameType:
return ConstraintKind::Equal;
case TypeMatchKind::ConformsTo:
return ConstraintKind::ConformsTo;
case TypeMatchKind::Subtype:
return ConstraintKind::Subtype;
case TypeMatchKind::Conversion:
return ConstraintKind::Conversion;
case TypeMatchKind::ExplicitConversion:
return ConstraintKind::ExplicitConversion;
case TypeMatchKind::ArgumentConversion:
return ConstraintKind::ArgumentConversion;
case TypeMatchKind::ArgumentTupleConversion:
return ConstraintKind::ArgumentTupleConversion;
case TypeMatchKind::OperatorArgumentTupleConversion:
return ConstraintKind::OperatorArgumentTupleConversion;
case TypeMatchKind::OperatorArgumentConversion:
return ConstraintKind::OperatorArgumentConversion;
}
llvm_unreachable("unhandled type matching kind");
}
static bool isStringCompatiblePointerBaseType(TypeChecker &TC,
DeclContext *DC,
Type baseType) {
// Allow strings to be passed to pointer-to-byte or pointer-to-void types.
if (baseType->isEqual(TC.getInt8Type(DC)))
return true;
if (baseType->isEqual(TC.getUInt8Type(DC)))
return true;
if (baseType->isEqual(TC.Context.TheEmptyTupleType))
return true;
return false;
}
/// Determine whether the given type is a value type to which we can bridge a
/// value of its corresponding class type, such as 'String' bridging from
/// NSString.
static bool allowsBridgingFromObjC(TypeChecker &tc, DeclContext *dc,
Type type) {
auto objcType = tc.getBridgedToObjC(dc, type);
if (!objcType)
return false;
auto objcClass = objcType->getClassOrBoundGenericClass();
if (!objcClass)
return false;
return true;
}
/// Check whether the given value type is one of a few specific
/// bridged types.
static bool isArrayDictionarySetOrString(const ASTContext &ctx, Type type) {
if (auto structDecl = type->getStructOrBoundGenericStruct()) {
return (structDecl == ctx.getStringDecl() ||
structDecl == ctx.getArrayDecl() ||
structDecl == ctx.getDictionaryDecl() ||
structDecl == ctx.getSetDecl());
}
return false;
}
/// Given that 'tupleTy' is the argument type of a function that's being
/// invoked with a single unlabeled argument, return the type of the parameter
/// that matches that argument, or the null type if such a match is impossible.
static Type getTupleElementTypeForSingleArgument(TupleType *tupleTy) {
Type result;
for (auto &param : tupleTy->getElements()) {
bool mustClaimArg = !param.isVararg() &&
param.getDefaultArgKind() == DefaultArgumentKind::None;
bool canClaimArg = !param.hasName();
if (!result && canClaimArg) {
result = param.isVararg() ? param.getVarargBaseTy() : param.getType();
} else if (mustClaimArg) {
return Type();
}
}
return result;
}
ConstraintSystem::SolutionKind
ConstraintSystem::matchTypes(Type type1, Type type2, TypeMatchKind kind,
unsigned flags,
ConstraintLocatorBuilder locator) {
// If we have type variables that have been bound to fixed types, look through
// to the fixed type.
TypeVariableType *typeVar1;
bool isArgumentTupleConversion
= kind == TypeMatchKind::ArgumentTupleConversion ||
kind == TypeMatchKind::OperatorArgumentTupleConversion;
type1 = getFixedTypeRecursive(type1, typeVar1,
kind == TypeMatchKind::SameType,
isArgumentTupleConversion);
auto desugar1 = type1->getDesugaredType();
TypeVariableType *typeVar2;
type2 = getFixedTypeRecursive(type2, typeVar2,
kind == TypeMatchKind::SameType,
isArgumentTupleConversion);
auto desugar2 = type2->getDesugaredType();
// If the types are obviously equivalent, we're done.
if (kind != TypeMatchKind::ConformsTo && desugar1->isEqual(desugar2))
return SolutionKind::Solved;
// If either (or both) types are type variables, unify the type variables.
if (typeVar1 || typeVar2) {
switch (kind) {
case TypeMatchKind::BindType:
case TypeMatchKind::BindToPointerType:
case TypeMatchKind::SameType: {
if (typeVar1 && typeVar2) {
auto rep1 = getRepresentative(typeVar1);
auto rep2 = getRepresentative(typeVar2);
if (rep1 == rep2) {
// We already merged these two types, so this constraint is
// trivially solved.
return SolutionKind::Solved;
}
// If exactly one of the type variables can bind to an lvalue, we
// can't merge these two type variables.
if (rep1->getImpl().canBindToLValue()
!= rep2->getImpl().canBindToLValue()) {
if (flags & TMF_GenerateConstraints) {
if (kind == TypeMatchKind::BindToPointerType) {
increaseScore(ScoreKind::SK_ScalarPointerConversion);
}
// Add a new constraint between these types. We consider the current
// type-matching problem to the "solved" by this addition, because
// this new constraint will be solved at a later point.
// Obviously, this must not happen at the top level, or the
// algorithm would not terminate.
addConstraint(getConstraintKind(kind), rep1, rep2,
getConstraintLocator(locator));
return SolutionKind::Solved;
}
return SolutionKind::Unsolved;
}
// Merge the equivalence classes corresponding to these two variables.
mergeEquivalenceClasses(rep1, rep2);
return SolutionKind::Solved;
}
// Provide a fixed type for the type variable.
bool wantRvalue = kind == TypeMatchKind::SameType;
if (typeVar1) {
// If we want an rvalue, get the rvalue.
if (wantRvalue)
type2 = type2->getRValueType();
// If the left-hand type variable cannot bind to an lvalue,
// but we still have an lvalue, fail.
if (!typeVar1->getImpl().canBindToLValue()) {
if (type2->isLValueType()) {
if (shouldRecordFailures()) {
recordFailure(getConstraintLocator(locator),
Failure::IsForbiddenLValue, type1, type2);
}
return SolutionKind::Error;
}
// Okay. Bind below.
}
// Check whether the type variable must be bound to a materializable
// type.
if (typeVar1->getImpl().mustBeMaterializable()) {
if (!type2->isMaterializable()) {
if (shouldRecordFailures()) {
// TODO: customize error message for closure vs. generic param
recordFailure(getConstraintLocator(locator),
Failure::IsNotMaterializable, type2);
}
return SolutionKind::Error;
} else {
setMustBeMaterializableRecursive(type2);
}
}
// A constraint that binds any pointer to a void pointer is
// ineffective, since any pointer can be converted to a void pointer.
if (kind == TypeMatchKind::BindToPointerType && desugar2->isVoid() &&
(flags & TMF_GenerateConstraints)) {
// Bind type1 to Void only as a last resort.
addConstraint(ConstraintKind::Defaultable, typeVar1, type2,
getConstraintLocator(locator));
return SolutionKind::Solved;
}
assignFixedType(typeVar1, type2);
// For symmetry with overload resolution, penalize conversions to empty
// existentials.
if (type2->isEmptyExistentialComposition())
increaseScore(ScoreKind::SK_EmptyExistentialConversion);
return SolutionKind::Solved;
}
// If we want an rvalue, get the rvalue.
if (wantRvalue)
type1 = type1->getRValueType();
if (!typeVar2->getImpl().canBindToLValue()) {
if (type1->isLValueType()) {
if (shouldRecordFailures()) {
recordFailure(getConstraintLocator(locator),
Failure::IsForbiddenLValue, type1, type2);
}
return SolutionKind::Error;
}
// Okay. Bind below.
}
assignFixedType(typeVar2, type1);
return SolutionKind::Solved;
}
case TypeMatchKind::BindParamType: {
if (typeVar2 && !typeVar1) {
if (auto *iot = dyn_cast<InOutType>(desugar1)) {
assignFixedType(typeVar2, LValueType::get(iot->getObjectType()));
} else {
assignFixedType(typeVar2, type1);
}
return SolutionKind::Solved;
} else if (typeVar1 && !typeVar2) {
if (auto *lvt = dyn_cast<LValueType>(desugar2)) {
assignFixedType(typeVar1, InOutType::get(lvt->getObjectType()));
} else {
assignFixedType(typeVar1, type2);
}
return SolutionKind::Solved;
}
return SolutionKind::Unsolved;
}
// We need to be careful about mapping 'raw' argument type variables to
// parameter tuples containing default args, or varargs in the first
// position. If we naively bind the type variable to the parameter tuple,
// we'll later end up looking to whatever expression created the type
// variable to find the declarations for default arguments. This can
// obviously be problematic if the expression in question is not an
// application. (For example, We don't want to introspect an 'if' expression
// to see if it has default arguments.) Instead, we should bind the type
// variable to the first element type of the tuple.
case TypeMatchKind::ArgumentTupleConversion:
if (typeVar1 &&
!typeVar1->getImpl().literalConformanceProto &&
(flags & TMF_GenerateConstraints) &&
dyn_cast<ParenType>(type1.getPointer())) {
if (auto tupleTy = type2->getAs<TupleType>()) {
if (auto tupleEltTy = getTupleElementTypeForSingleArgument(tupleTy)) {
addConstraint(getConstraintKind(kind),
typeVar1,
tupleEltTy,
getConstraintLocator(locator));
return SolutionKind::Solved;
}
}
}
SWIFT_FALLTHROUGH;
case TypeMatchKind::ConformsTo:
case TypeMatchKind::Subtype:
case TypeMatchKind::Conversion:
case TypeMatchKind::ExplicitConversion:
case TypeMatchKind::ArgumentConversion:
case TypeMatchKind::OperatorArgumentTupleConversion:
case TypeMatchKind::OperatorArgumentConversion:
if (flags & TMF_GenerateConstraints) {
// Add a new constraint between these types. We consider the current
// type-matching problem to the "solved" by this addition, because
// this new constraint will be solved at a later point.
// Obviously, this must not happen at the top level, or the algorithm
// would not terminate.
addConstraint(getConstraintKind(kind), type1, type2,
getConstraintLocator(locator));
return SolutionKind::Solved;
}
// We couldn't solve this constraint. If only one of the types is a type
// variable, perhaps we can do something with it below.
if (typeVar1 && typeVar2)
return typeVar1 == typeVar2 ? SolutionKind::Solved
: SolutionKind::Unsolved;
break;
}
}
llvm::SmallVector<RestrictionOrFix, 4> conversionsOrFixes;
bool concrete = !typeVar1 && !typeVar2;
// If this is an argument conversion, handle it directly. The rules are
// different from normal conversions.
if (kind == TypeMatchKind::ArgumentTupleConversion ||
kind == TypeMatchKind::OperatorArgumentTupleConversion) {
if (concrete) {
return ::matchCallArguments(*this, kind, type1, type2, locator);
}
if (flags & TMF_GenerateConstraints) {
// Add a new constraint between these types. We consider the current
// type-matching problem to the "solved" by this addition, because
// this new constraint will be solved at a later point.
// Obviously, this must not happen at the top level, or the algorithm
// would not terminate.
addConstraint(getConstraintKind(kind), type1, type2,
getConstraintLocator(locator));
return SolutionKind::Solved;
}
return SolutionKind::Unsolved;
}
// Decompose parallel structure.
unsigned subFlags = (flags | TMF_GenerateConstraints) & ~TMF_ApplyingFix;
if (desugar1->getKind() == desugar2->getKind()) {
switch (desugar1->getKind()) {
#define SUGARED_TYPE(id, parent) case TypeKind::id:
#define TYPE(id, parent)
#include "swift/AST/TypeNodes.def"
llvm_unreachable("Type has not been desugared completely");
#define ARTIFICIAL_TYPE(id, parent) case TypeKind::id:
#define TYPE(id, parent)
#include "swift/AST/TypeNodes.def"
llvm_unreachable("artificial type in constraint");
#define BUILTIN_TYPE(id, parent) case TypeKind::id:
#define TYPE(id, parent)
#include "swift/AST/TypeNodes.def"
case TypeKind::Module:
if (desugar1 == desugar2) {
return SolutionKind::Solved;
}
return SolutionKind::Error;
case TypeKind::Error:
case TypeKind::Unresolved:
return SolutionKind::Error;
case TypeKind::GenericTypeParam:
case TypeKind::DependentMember:
llvm_unreachable("unmapped dependent type in type checker");
case TypeKind::TypeVariable:
case TypeKind::Archetype:
// Nothing to do here; handle type variables and archetypes below.
break;
case TypeKind::Tuple: {
// Try the tuple-to-tuple conversion.
conversionsOrFixes.push_back(ConversionRestrictionKind::TupleToTuple);
break;
}
case TypeKind::Enum:
case TypeKind::Struct:
case TypeKind::Class: {
auto nominal1 = cast<NominalType>(desugar1);
auto nominal2 = cast<NominalType>(desugar2);
if (nominal1->getDecl() == nominal2->getDecl()) {
conversionsOrFixes.push_back(ConversionRestrictionKind::DeepEquality);
}
// Check for CF <-> ObjectiveC bridging.
if (desugar1->getKind() == TypeKind::Class &&
kind >= TypeMatchKind::Subtype) {
auto class1 = cast<ClassDecl>(nominal1->getDecl());
auto class2 = cast<ClassDecl>(nominal2->getDecl());
// CF -> Objective-C via toll-free bridging.
if (class1->isForeign() && !class2->isForeign() &&
class1->getAttrs().hasAttribute<ObjCBridgedAttr>()) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::CFTollFreeBridgeToObjC);
}
// Objective-C -> CF via toll-free bridging.
if (class2->isForeign() && !class1->isForeign() &&
class2->getAttrs().hasAttribute<ObjCBridgedAttr>()) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::ObjCTollFreeBridgeToCF);
}
}
break;
}
case TypeKind::DynamicSelf:
// FIXME: Deep equality? What is the rule between two DynamicSelfs?
break;
case TypeKind::Protocol:
// Nothing to do here; try existential and user-defined conversions below.
break;
case TypeKind::Metatype:
case TypeKind::ExistentialMetatype: {
auto meta1 = cast<AnyMetatypeType>(desugar1);
auto meta2 = cast<AnyMetatypeType>(desugar2);
TypeMatchKind subKind = TypeMatchKind::SameType;
// A.Type < B.Type if A < B and both A and B are classes.
if (isa<MetatypeType>(desugar1) &&
kind != TypeMatchKind::SameType &&
meta1->getInstanceType()->mayHaveSuperclass() &&
meta2->getInstanceType()->getClassOrBoundGenericClass())
subKind = std::min(kind, TypeMatchKind::Subtype);
// P.Type < Q.Type if P < Q, both P and Q are protocols, and P.Type
// and Q.Type are both existential metatypes.
else if (isa<ExistentialMetatypeType>(meta1)
&& isa<ExistentialMetatypeType>(meta2))
subKind = std::min(kind, TypeMatchKind::Subtype);
return matchTypes(meta1->getInstanceType(), meta2->getInstanceType(),
subKind, subFlags,
locator.withPathElement(
ConstraintLocator::InstanceType));
}
case TypeKind::Function:
return matchFunctionTypes(cast<FunctionType>(desugar1),
cast<FunctionType>(desugar2),
kind, flags, locator);
case TypeKind::PolymorphicFunction:
case TypeKind::GenericFunction:
llvm_unreachable("Polymorphic function type should have been opened");
case TypeKind::ProtocolComposition:
// Existential types handled below.
break;
case TypeKind::LValue:
if (kind == TypeMatchKind::BindParamType) {
recordFailure(getConstraintLocator(locator),
Failure::IsForbiddenLValue, type1, type2);
return SolutionKind::Error;
}
return matchTypes(cast<LValueType>(desugar1)->getObjectType(),
cast<LValueType>(desugar2)->getObjectType(),
TypeMatchKind::SameType, subFlags,
locator.withPathElement(
ConstraintLocator::ArrayElementType));
case TypeKind::InOut:
// If the RHS is an inout type, the LHS must be an @lvalue type.
if (kind == TypeMatchKind::BindParamType ||
kind >= TypeMatchKind::OperatorArgumentConversion) {
if (shouldRecordFailures())
recordFailure(getConstraintLocator(locator),
Failure::IsForbiddenLValue, type1, type2);
return SolutionKind::Error;
}
return matchTypes(cast<InOutType>(desugar1)->getObjectType(),
cast<InOutType>(desugar2)->getObjectType(),
TypeMatchKind::SameType, subFlags,
locator.withPathElement(ConstraintLocator::ArrayElementType));
case TypeKind::UnboundGeneric:
llvm_unreachable("Unbound generic type should have been opened");
case TypeKind::BoundGenericClass:
case TypeKind::BoundGenericEnum:
case TypeKind::BoundGenericStruct: {
auto bound1 = cast<BoundGenericType>(desugar1);
auto bound2 = cast<BoundGenericType>(desugar2);
if (bound1->getDecl() == bound2->getDecl()) {
conversionsOrFixes.push_back(ConversionRestrictionKind::DeepEquality);
}
break;
}
}
}
if (concrete && kind >= TypeMatchKind::Subtype) {
auto tuple1 = type1->getAs<TupleType>();
auto tuple2 = type2->getAs<TupleType>();
// Detect when the source and destination are both permit scalar
// conversions, but the source has a name and the destination does not have
// the same name.
bool tuplesWithMismatchedNames = false;
if (tuple1 && tuple2) {
int scalar1 = tuple1->getElementForScalarInit();
int scalar2 = tuple2->getElementForScalarInit();
if (scalar1 >= 0 && scalar2 >= 0) {
auto name1 = tuple1->getElement(scalar1).getName();
auto name2 = tuple2->getElement(scalar2).getName();
tuplesWithMismatchedNames = !name1.empty() && name1 != name2;
}
}
if (tuple2 && !tuplesWithMismatchedNames) {
// A scalar type is a trivial subtype of a one-element, non-variadic tuple
// containing a single element if the scalar type is a subtype of
// the type of that tuple's element.
//
// A scalar type can be converted to an argument tuple so long as
// there is at most one non-defaulted element.
// For non-argument tuples, we can do the same conversion but not
// to a tuple with varargs.
if ((tuple2->getNumElements() == 1 &&
!tuple2->getElement(0).isVararg()) ||
(kind >= TypeMatchKind::Conversion &&
tuple2->getElementForScalarInit() >= 0 &&
(isArgumentTupleConversion ||
!tuple2->getVarArgsBaseType()))) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::ScalarToTuple);
// FIXME: Prohibits some user-defined conversions for tuples.
goto commit_to_conversions;
}
}
if (tuple1 && !tuplesWithMismatchedNames) {
// A single-element tuple can be a trivial subtype of a scalar.
if (tuple1->getNumElements() == 1 &&
!tuple1->getElement(0).isVararg()) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::TupleToScalar);
}
}
// Subclass-to-superclass conversion.
if (type1->mayHaveSuperclass() && type2->mayHaveSuperclass() &&
type2->getClassOrBoundGenericClass() &&
type1->getClassOrBoundGenericClass()
!= type2->getClassOrBoundGenericClass()) {
conversionsOrFixes.push_back(ConversionRestrictionKind::Superclass);
}
// Metatype to object conversion.
//
// Class and protocol metatypes are interoperable with certain Objective-C
// runtime classes, but only when ObjC interop is enabled.
if (TC.getLangOpts().EnableObjCInterop) {
// These conversions are between concrete types that don't need further
// resolution, so we can consider them immediately solved.
auto addSolvedRestrictedConstraint
= [&](ConversionRestrictionKind restriction) -> SolutionKind {
auto constraint = Constraint::createRestricted(*this,
ConstraintKind::Subtype,
restriction,
type1, type2,
getConstraintLocator(locator));
addConstraint(constraint);
return SolutionKind::Solved;
};
if (auto meta1 = type1->getAs<MetatypeType>()) {
if (meta1->getInstanceType()->mayHaveSuperclass()
&& type2->isAnyObject()) {
increaseScore(ScoreKind::SK_UserConversion);
return addSolvedRestrictedConstraint(
ConversionRestrictionKind::ClassMetatypeToAnyObject);
}
// Single @objc protocol value metatypes can be converted to the ObjC
// Protocol class type.
auto isProtocolClassType = [&](Type t) -> bool {
if (auto classDecl = t->getClassOrBoundGenericClass())
if (classDecl->getName() == getASTContext().Id_Protocol
&& classDecl->getModuleContext()->getName()
== getASTContext().Id_ObjectiveC)
return true;
return false;
};
if (auto protoTy = meta1->getInstanceType()->getAs<ProtocolType>()) {
if (protoTy->getDecl()->isObjC()
&& isProtocolClassType(type2)) {
increaseScore(ScoreKind::SK_UserConversion);
return addSolvedRestrictedConstraint(
ConversionRestrictionKind::ProtocolMetatypeToProtocolClass);
}
}
}
if (auto meta1 = type1->getAs<ExistentialMetatypeType>()) {
// Class-constrained existential metatypes can be converted to AnyObject.
if (meta1->getInstanceType()->isClassExistentialType()
&& type2->isAnyObject()) {
increaseScore(ScoreKind::SK_UserConversion);
return addSolvedRestrictedConstraint(
ConversionRestrictionKind::ExistentialMetatypeToAnyObject);
}
}
}
// Implicit collection conversions.
if (kind >= TypeMatchKind::Conversion) {
if (isArrayType(desugar1) && isArrayType(desugar2)) {
conversionsOrFixes.push_back(ConversionRestrictionKind::ArrayUpcast);
} else if (isDictionaryType(desugar1) && isDictionaryType(desugar2)) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::DictionaryUpcast);
} else if (isSetType(desugar1) && isSetType(desugar2)) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::SetUpcast);
}
}
}
if (kind == TypeMatchKind::BindToPointerType) {
if (desugar2->isEqual(getASTContext().TheEmptyTupleType))
return SolutionKind::Solved;
}
if (concrete && kind >= TypeMatchKind::Conversion) {
// An lvalue of type T1 can be converted to a value of type T2 so long as
// T1 is convertible to T2 (by loading the value).
if (type1->is<LValueType>())
conversionsOrFixes.push_back(
ConversionRestrictionKind::LValueToRValue);
// An expression can be converted to an auto-closure function type, creating
// an implicit closure.
if (auto function2 = type2->getAs<FunctionType>()) {
if (function2->isAutoClosure())
return matchTypes(type1, function2->getResult(), kind, subFlags,
locator.withPathElement(ConstraintLocator::Load));
}
// Bridging from a value type to an Objective-C class type.
// FIXME: Banned for operator parameters, like user conversions are.
// NOTE: The plan for <rdar://problem/18311362> was to make such bridging
// conversions illegal except when explicitly converting with the 'as'
// operator. But using a String to subscript an [NSObject : AnyObject] is
// sufficiently common due to bridging that disallowing such conversions is
// not yet feasible, and a more targeted fix in the type checker is hard to
// justify.
if (type1->isPotentiallyBridgedValueType() &&
type1->getAnyNominal()
!= TC.Context.getImplicitlyUnwrappedOptionalDecl() &&
!(flags & TMF_ApplyingOperatorParameter)) {
auto isBridgeableTargetType = type2->isBridgeableObjectType();
// Allow bridged conversions to CVarArgType through NSObject.
if (!isBridgeableTargetType && type2->isExistentialType()) {
if (auto nominalType = type2->getAs<NominalType>())
isBridgeableTargetType = nominalType->getDecl()->getName() ==
TC.Context.Id_CVarArgType;
}
if (isBridgeableTargetType && TC.getBridgedToObjC(DC, type1)) {
conversionsOrFixes.push_back(ConversionRestrictionKind::BridgeToObjC);
}
}
if (kind == TypeMatchKind::ExplicitConversion) {
// Bridging from an Objective-C class type to a value type.
// Note that specifically require a class or class-constrained archetype
// here, because archetypes cannot be bridged.
if (type1->mayHaveSuperclass() && type2->isPotentiallyBridgedValueType() &&
type2->getAnyNominal()
!= TC.Context.getImplicitlyUnwrappedOptionalDecl() &&
allowsBridgingFromObjC(TC, DC, type2)) {
conversionsOrFixes.push_back(ConversionRestrictionKind::BridgeFromObjC);
}
// Bridging from an ErrorType to an Objective-C NSError.
if (auto errorType = TC.Context.getProtocol(KnownProtocolKind::ErrorType)) {
if (TC.containsProtocol(type1, errorType, DC,
ConformanceCheckFlags::InExpression))
if (auto NSErrorTy = TC.getNSErrorType(DC))
if (type2->isEqual(NSErrorTy))
conversionsOrFixes.push_back(
ConversionRestrictionKind::BridgeToNSError);
}
}
// Pointer arguments can be converted from pointer-compatible types.
if (kind >= TypeMatchKind::ArgumentConversion) {
if (auto bgt2 = type2->getAs<BoundGenericType>()) {
if (bgt2->getDecl() == getASTContext().getUnsafeMutablePointerDecl()
|| bgt2->getDecl() == getASTContext().getUnsafePointerDecl()) {
// UnsafeMutablePointer can be converted from an inout reference to a
// scalar or array.
if (auto inoutType1 = dyn_cast<InOutType>(desugar1)) {
auto inoutBaseType = inoutType1->getInOutObjectType();
auto isWrappedArray = isArrayType(inoutBaseType);
if (auto baseTyVar1 = dyn_cast<TypeVariableType>(inoutBaseType.
getPointer())) {
TypeVariableType *tv1;
auto bt1 = getFixedTypeRecursive(baseTyVar1, tv1,
kind == TypeMatchKind::SameType,
isArgumentTupleConversion);
isWrappedArray = isArrayType(bt1);
}
if (isWrappedArray) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::ArrayToPointer);
}
conversionsOrFixes.push_back(
ConversionRestrictionKind::InoutToPointer);
}
if (!(flags & TMF_ApplyingOperatorParameter) &&
// Operators cannot use these implicit conversions.
(kind == TypeMatchKind::ArgumentConversion ||
kind == TypeMatchKind::ArgumentTupleConversion)) {
auto bgt1 = type1->getAs<BoundGenericType>();
// We can potentially convert from an UnsafeMutablePointer
// of a different type, if we're a void pointer.
if (bgt1 && bgt1->getDecl()
== getASTContext().getUnsafeMutablePointerDecl()) {
// Favor an UnsafeMutablePointer-to-UnsafeMutablePointer
// conversion.
if (bgt1->getDecl() != bgt2->getDecl())
increaseScore(ScoreKind::SK_ScalarPointerConversion);
conversionsOrFixes.push_back(
ConversionRestrictionKind::PointerToPointer);
}
// UnsafePointer can also be converted from an array
// or string value, or a UnsafePointer or
// AutoreleasingUnsafeMutablePointer.
if (bgt2->getDecl() == getASTContext().getUnsafePointerDecl()){
if (isArrayType(type1)) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::ArrayToPointer);
}
// The pointer can be converted from a string, if the element type
// is compatible.
if (type1->isEqual(TC.getStringType(DC))) {
TypeVariableType *tv = nullptr;
auto baseTy = getFixedTypeRecursive(bgt2->getGenericArgs()[0],
tv, false, false);
if (tv || isStringCompatiblePointerBaseType(TC, DC, baseTy))
conversionsOrFixes.push_back(
ConversionRestrictionKind::StringToPointer);
}
if (bgt1 && bgt1->getDecl()
== getASTContext().getUnsafePointerDecl()) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::PointerToPointer);
}
if (bgt1 && bgt1->getDecl() == getASTContext()
.getAutoreleasingUnsafeMutablePointerDecl()) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::PointerToPointer);
}
}
}
} else if (
bgt2->getDecl() == getASTContext()
.getAutoreleasingUnsafeMutablePointerDecl()) {
// AutoUnsafeMutablePointer can be converted from an inout
// reference to a scalar.
if (type1->is<InOutType>()) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::InoutToPointer);
}
}
}
}
}
if (concrete && kind >= TypeMatchKind::OperatorArgumentConversion) {
// If the RHS is an inout type, the LHS must be an @lvalue type.
if (auto *iot = type2->getAs<InOutType>()) {
return matchTypes(type1, LValueType::get(iot->getObjectType()),
kind, subFlags,
locator.withPathElement(
ConstraintLocator::ArrayElementType));
}
}
// Conformance of a metatype to an existential metatype is actually
// equivalent to a conformance relationship on the instance types.
// This applies to nested metatype levels, so if A : P then
// A.Type : P.Type.
if (concrete && kind >= TypeMatchKind::ConformsTo) {
if (auto meta1 = type1->getAs<MetatypeType>()) {
if (auto meta2 = type2->getAs<ExistentialMetatypeType>()) {
return matchTypes(meta1->getInstanceType(),
meta2->getInstanceType(),
TypeMatchKind::ConformsTo, subFlags,
locator.withPathElement(
ConstraintLocator::InstanceType));
}
}
}
// Instance type check for the above. We are going to check conformance once
// we hit commit_to_conversions below, but we have to add a token restriction
// to ensure we wrap the metatype value in a metatype erasure.
if (concrete && type2->isExistentialType()) {
// If we're binding to an empty existential, we need to make sure that the
// conversion is valid.
if (kind == TypeMatchKind::BindType &&
type2->isEmptyExistentialComposition()) {
conversionsOrFixes.push_back(ConversionRestrictionKind::Existential);
addConstraint(ConstraintKind::SelfObjectOfProtocol,
type1, type2, getConstraintLocator(locator));
return SolutionKind::Solved;
}
if (kind == TypeMatchKind::ConformsTo) {
conversionsOrFixes.push_back(ConversionRestrictionKind::
MetatypeToExistentialMetatype);
} else if (kind >= TypeMatchKind::Subtype) {
conversionsOrFixes.push_back(ConversionRestrictionKind::Existential);
}
}
// A value of type T can be converted to type U? if T is convertible to U.
// A value of type T? can be converted to type U? if T is convertible to U.
// The above conversions also apply to implicitly unwrapped optional types,
// except that there is no implicit conversion from T? to T!.
{
BoundGenericType *boundGenericType2;
if (concrete && kind >= TypeMatchKind::Subtype &&
(boundGenericType2 = type2->getAs<BoundGenericType>())) {
auto decl2 = boundGenericType2->getDecl();
if (auto optionalKind2 = decl2->classifyAsOptionalType()) {
assert(boundGenericType2->getGenericArgs().size() == 1);
BoundGenericType *boundGenericType1 = type1->getAs<BoundGenericType>();
if (boundGenericType1) {
auto decl1 = boundGenericType1->getDecl();
if (decl1 == decl2) {
assert(boundGenericType1->getGenericArgs().size() == 1);
conversionsOrFixes.push_back(
ConversionRestrictionKind::OptionalToOptional);
} else if (optionalKind2 == OTK_Optional &&
decl1 == TC.Context.getImplicitlyUnwrappedOptionalDecl()) {
assert(boundGenericType1->getGenericArgs().size() == 1);
conversionsOrFixes.push_back(
ConversionRestrictionKind::ImplicitlyUnwrappedOptionalToOptional);
} else if (optionalKind2 == OTK_ImplicitlyUnwrappedOptional &&
kind >= TypeMatchKind::Conversion &&
decl1 == TC.Context.getOptionalDecl()) {
assert(boundGenericType1->getGenericArgs().size() == 1);
conversionsOrFixes.push_back(
ConversionRestrictionKind::OptionalToImplicitlyUnwrappedOptional);
}
}
// Do not attempt a value-to-optional conversion when resolving the
// applicable overloads for an operator application with nil operands.
if (!(subFlags & TMF_ApplyingOperatorWithNil)) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::ValueToOptional);
}
}
}
}
// A value of type T! can be (unsafely) forced to U if T
// is convertible to U.
{
Type objectType1;
if (concrete && kind >= TypeMatchKind::Conversion &&
(objectType1 = lookThroughImplicitlyUnwrappedOptionalType(type1))) {
conversionsOrFixes.push_back(
ConversionRestrictionKind::ForceUnchecked);
}
}
// If the types disagree, but we're comparing a non-void, single-expression
// closure result type to a void function result type, allow the conversion.
{
if (concrete && kind >= TypeMatchKind::Subtype && type2->isVoid()) {
SmallVector<LocatorPathElt, 2> parts;
locator.getLocatorParts(parts);
while (!parts.empty()) {
if (parts.back().getKind() == ConstraintLocator::ClosureResult) {
increaseScore(SK_FunctionConversion);
return SolutionKind::Solved;
}
parts.pop_back();
}
}
}
if (concrete && kind == TypeMatchKind::BindParamType) {
if (auto *iot = dyn_cast<InOutType>(desugar1)) {
if (auto *lvt = dyn_cast<LValueType>(desugar2)) {
return matchTypes(iot->getObjectType(), lvt->getObjectType(),
TypeMatchKind::BindType, subFlags,
locator.withPathElement(
ConstraintLocator::ArrayElementType));
}
}
}
commit_to_conversions:
// When we hit this point, we're committed to the set of potential
// conversions recorded thus far.
//
//
// FIXME: One should only jump to this label in the case where we want to
// cut off other potential conversions because we know none of them apply.
// Gradually, those gotos should go away as we can handle more kinds of
// conversions via disjunction constraints.
// If we should attempt fixes, add those to the list. They'll only be visited
// if there are no other possible solutions.
if (shouldAttemptFixes() && !typeVar1 && !typeVar2 &&
!(flags & TMF_ApplyingFix) && kind >= TypeMatchKind::Conversion) {
Type objectType1 = type1->getRValueObjectType();
// If we have an optional type, try to force-unwrap it.
// FIXME: Should we also try '?'?
if (objectType1->getOptionalObjectType()) {
conversionsOrFixes.push_back(FixKind::ForceOptional);
}
// If we have a value of type AnyObject that we're trying to convert to
// a class, force a downcast.
// FIXME: Also allow types bridged through Objective-C classes.
if (objectType1->isAnyObject() &&
type2->getClassOrBoundGenericClass()) {
conversionsOrFixes.push_back(Fix::getForcedDowncast(*this, type2));
}
// Look through IUO's.
auto type1WithoutIUO = objectType1;
if (auto elt = type1WithoutIUO->getImplicitlyUnwrappedOptionalObjectType())
type1WithoutIUO = elt;
// If we could perform a bridging cast, try it.
if (isArrayDictionarySetOrString(TC.Context, type2) &&
TC.getDynamicBridgedThroughObjCClass(DC, type1WithoutIUO, type2)){
conversionsOrFixes.push_back(Fix::getForcedDowncast(*this, type2));
}
// If we're converting an lvalue to an inout type, add the missing '&'.
if (type2->getRValueType()->is<InOutType>() && type1->is<LValueType>()) {
conversionsOrFixes.push_back(FixKind::AddressOf);
}
}
if (conversionsOrFixes.empty()) {
// If one of the types is a type variable, we leave this unsolved.
if (typeVar1 || typeVar2)
return SolutionKind::Unsolved;
return SolutionKind::Error;
}
// Where there is more than one potential conversion, create a disjunction
// so that we'll explore all of the options.
if (conversionsOrFixes.size() > 1) {
auto fixedLocator = getConstraintLocator(locator);
SmallVector<Constraint *, 2> constraints;
for (auto potential : conversionsOrFixes) {
auto constraintKind = getConstraintKind(kind);
if (auto restriction = potential.getRestriction()) {
// Determine the constraint kind. For a deep equality constraint, only
// perform equality.
if (*restriction == ConversionRestrictionKind::DeepEquality)
constraintKind = ConstraintKind::Equal;
constraints.push_back(
Constraint::createRestricted(*this, constraintKind, *restriction,
type1, type2, fixedLocator));
continue;
}
// If the first thing we found is a fix, add a "don't fix" marker.
if (conversionsOrFixes.empty()) {
constraints.push_back(
Constraint::createFixed(*this, constraintKind, FixKind::None,
type1, type2, fixedLocator));
}
auto fix = *potential.getFix();
constraints.push_back(
Constraint::createFixed(*this, constraintKind, fix, type1, type2,
fixedLocator));
}
addConstraint(Constraint::createDisjunction(*this, constraints,
fixedLocator));
return SolutionKind::Solved;
}
// For a single potential conversion, directly recurse, so that we
// don't allocate a new constraint or constraint locator.
// Handle restrictions.
if (auto restriction = conversionsOrFixes[0].getRestriction()) {
ConstraintRestrictions.push_back(
std::make_tuple(type1, type2, *restriction));
if (flags & TMF_UnwrappingOptional) {
subFlags |= TMF_UnwrappingOptional;
}
return simplifyRestrictedConstraint(*restriction, type1, type2,
kind, subFlags, locator);
}
// Handle fixes.
auto fix = *conversionsOrFixes[0].getFix();
return simplifyFixConstraint(fix, type1, type2, kind, subFlags, locator);
}
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyConstructionConstraint(Type valueType,
FunctionType *fnType,
unsigned flags,
ConstraintLocator *locator) {
// Desugar the value type.
auto desugarValueType = valueType->getDesugaredType();
// If we have a type variable that has been bound to a fixed type,
// look through to that fixed type.
auto desugarValueTypeVar = dyn_cast<TypeVariableType>(desugarValueType);
if (desugarValueTypeVar) {
if (auto fixed = getFixedType(desugarValueTypeVar)) {
valueType = fixed;
desugarValueType = fixed->getDesugaredType();
desugarValueTypeVar = nullptr;
}
}
Type argType = fnType->getInput();
Type resultType = fnType->getResult();
switch (desugarValueType->getKind()) {
#define SUGARED_TYPE(id, parent) case TypeKind::id:
#define TYPE(id, parent)
#include "swift/AST/TypeNodes.def"
llvm_unreachable("Type has not been desugared completely");
#define ARTIFICIAL_TYPE(id, parent) case TypeKind::id:
#define TYPE(id, parent)
#include "swift/AST/TypeNodes.def"
llvm_unreachable("artificial type in constraint");
case TypeKind::Unresolved:
case TypeKind::Error:
return SolutionKind::Error;
case TypeKind::GenericFunction:
case TypeKind::GenericTypeParam:
case TypeKind::DependentMember:
llvm_unreachable("unmapped dependent type");
case TypeKind::TypeVariable:
return SolutionKind::Unsolved;
case TypeKind::Tuple: {
// Tuple construction is simply tuple conversion.
if (matchTypes(resultType, desugarValueType,
TypeMatchKind::BindType,
flags,
ConstraintLocatorBuilder(locator)
.withPathElement(ConstraintLocator::ApplyFunction))
== SolutionKind::Error)
return SolutionKind::Error;
return matchTypes(argType, valueType, TypeMatchKind::Conversion,
flags|TMF_GenerateConstraints, locator);
}
case TypeKind::Enum:
case TypeKind::Struct:
case TypeKind::Class:
case TypeKind::BoundGenericClass:
case TypeKind::BoundGenericEnum:
case TypeKind::BoundGenericStruct:
case TypeKind::Archetype:
case TypeKind::DynamicSelf:
case TypeKind::ProtocolComposition:
case TypeKind::Protocol:
// Break out to handle the actual construction below.
break;
case TypeKind::PolymorphicFunction:
llvm_unreachable("Polymorphic function type should have been opened");
case TypeKind::UnboundGeneric:
llvm_unreachable("Unbound generic type should have been opened");
#define BUILTIN_TYPE(id, parent) case TypeKind::id:
#define TYPE(id, parent)
#include "swift/AST/TypeNodes.def"
case TypeKind::ExistentialMetatype:
case TypeKind::Metatype:
case TypeKind::Function:
case TypeKind::LValue:
case TypeKind::InOut:
case TypeKind::Module:
return SolutionKind::Error;
}
NameLookupOptions lookupOptions = defaultConstructorLookupOptions;
if (isa<AbstractFunctionDecl>(DC))
lookupOptions |= NameLookupFlags::KnownPrivate;
auto ctors = TC.lookupConstructors(DC, valueType, lookupOptions);
if (!ctors) {
// If we are supposed to record failures, do so.
if (shouldRecordFailures()) {
recordFailure(locator, Failure::NoPublicInitializers, valueType);
}
return SolutionKind::Error;
}
auto &context = getASTContext();
auto name = context.Id_init;
auto applyLocator = getConstraintLocator(locator,
ConstraintLocator::ApplyArgument);
auto fnLocator = getConstraintLocator(locator,
ConstraintLocator::ApplyFunction);
auto tv = createTypeVariable(applyLocator,
TVO_CanBindToLValue|TVO_PrefersSubtypeBinding);
// The constructor will have function type T -> T2, for a fresh type
// variable T. T2 is the result type provided via the construction
// constraint itself.
addValueMemberConstraint(MetatypeType::get(valueType, TC.Context), name,
FunctionType::get(tv, resultType),
getConstraintLocator(
fnLocator,
ConstraintLocator::ConstructorMember));
// The first type must be convertible to the constructor's argument type.
addConstraint(ConstraintKind::ArgumentTupleConversion, argType, tv,
applyLocator);
return SolutionKind::Solved;
}
ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
Type type,
Type protocol,
ConstraintKind kind,
ConstraintLocatorBuilder locator,
unsigned flags) {
if (auto proto = protocol->getAs<ProtocolType>()) {
return simplifyConformsToConstraint(type, proto->getDecl(), kind,
locator, flags);
}
return matchExistentialTypes(type, protocol, kind, flags, locator);
}
ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
Type type,
ProtocolDecl *protocol,
ConstraintKind kind,
ConstraintLocatorBuilder locator,
unsigned flags) {
// Dig out the fixed type to which this type refers.
TypeVariableType *typeVar;
type = getFixedTypeRecursive(type, typeVar, /*wantRValue=*/true);
// If we hit a type variable without a fixed type, we can't
// solve this yet.
if (typeVar)
return SolutionKind::Unsolved;
// For purposes of argument type matching, existential types don't need to
// conform -- they only need to contain the protocol, so check that
// separately.
switch (kind) {
case ConstraintKind::SelfObjectOfProtocol:
if (TC.containsProtocol(type, protocol, DC,
ConformanceCheckFlags::InExpression))
return SolutionKind::Solved;
break;
case ConstraintKind::ConformsTo:
// Check whether this type conforms to the protocol.
if (TC.conformsToProtocol(type, protocol, DC,
ConformanceCheckFlags::InExpression))
return SolutionKind::Solved;
break;
default:
llvm_unreachable("bad constraint kind");
}
if (!shouldAttemptFixes())
return SolutionKind::Error;
// See if there's anything we can do to fix the conformance:
OptionalTypeKind optionalKind;
if (auto optionalObjectType = type->getAnyOptionalObjectType(optionalKind)) {
if (protocol->isSpecificProtocol(KnownProtocolKind::BooleanType)) {
// Optionals don't conform to BooleanType; suggest '!= nil'.
if (recordFix(FixKind::OptionalToBoolean, getConstraintLocator(locator)))
return SolutionKind::Error;
return SolutionKind::Solved;
} else if (optionalKind == OTK_Optional) {
// The underlying type of an optional may conform to the protocol if the
// optional doesn't; suggest forcing if that's the case.
auto result = simplifyConformsToConstraint(
optionalObjectType, protocol, kind,
locator.withPathElement(LocatorPathElt::getGenericArgument(0)), flags);
if (result == SolutionKind::Solved) {
if (recordFix(FixKind::ForceOptional, getConstraintLocator(locator))) {
return SolutionKind::Error;
}
}
return result;
}
}
// There's nothing more we can do; fail.
return SolutionKind::Error;
}
/// Determine the kind of checked cast to perform from the given type to
/// the given type.
///
/// This routine does not attempt to check whether the cast can actually
/// succeed; that's the caller's responsibility.
static CheckedCastKind getCheckedCastKind(ConstraintSystem *cs,
Type fromType,
Type toType) {
// Array downcasts are handled specially.
if (cs->isArrayType(fromType) && cs->isArrayType(toType)) {
return CheckedCastKind::ArrayDowncast;
}
// Dictionary downcasts are handled specially.
if (cs->isDictionaryType(fromType) && cs->isDictionaryType(toType)) {
return CheckedCastKind::DictionaryDowncast;
}
// Set downcasts are handled specially.
if (cs->isSetType(fromType) && cs->isSetType(toType)) {
return CheckedCastKind::SetDowncast;
}
// If we can bridge through an Objective-C class, do so.
auto &tc = cs->getTypeChecker();
if (tc.getDynamicBridgedThroughObjCClass(cs->DC, fromType, toType)) {
return CheckedCastKind::BridgeFromObjectiveC;
}
return CheckedCastKind::ValueCast;
}
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyCheckedCastConstraint(
Type fromType, Type toType,
ConstraintLocatorBuilder locator) {
do {
// Dig out the fixed type to which this type refers.
TypeVariableType *typeVar1;
fromType = getFixedTypeRecursive(fromType, typeVar1, /*wantRValue=*/true);
// If we hit a type variable without a fixed type, we can't
// solve this yet.
if (typeVar1)
return SolutionKind::Unsolved;
// Dig out the fixed type to which this type refers.
TypeVariableType *typeVar2;
toType = getFixedTypeRecursive(toType, typeVar2, /*wantRValue=*/true);
// If we hit a type variable without a fixed type, we can't
// solve this yet.
if (typeVar2)
return SolutionKind::Unsolved;
Type origFromType = fromType;
Type origToType = toType;
// Peel off optionals metatypes from the types, because we might cast through
// them.
toType = toType->lookThroughAllAnyOptionalTypes();
fromType = fromType->lookThroughAllAnyOptionalTypes();
// Peel off metatypes, since if we can cast two types, we can cast their
// metatypes.
while (auto toMetatype = toType->getAs<MetatypeType>()) {
auto fromMetatype = fromType->getAs<MetatypeType>();
if (!fromMetatype)
break;
toType = toMetatype->getInstanceType();
fromType = fromMetatype->getInstanceType();
}
// Peel off a potential layer of existential<->concrete metatype conversion.
if (auto toMetatype = toType->getAs<AnyMetatypeType>()) {
if (auto fromMetatype = fromType->getAs<MetatypeType>()) {
toType = toMetatype->getInstanceType();
fromType = fromMetatype->getInstanceType();
}
}
// If nothing changed, we're done.
if (fromType.getPointer() == origFromType.getPointer() &&
toType.getPointer() == origToType.getPointer())
break;
} while (true);
auto kind = getCheckedCastKind(this, fromType, toType);
switch (kind) {
case CheckedCastKind::ArrayDowncast: {
auto fromBaseType = getBaseTypeForArrayType(fromType.getPointer());
auto toBaseType = getBaseTypeForArrayType(toType.getPointer());
// FIXME: Deal with from/to base types that haven't been solved
// down to type variables yet.
// Check whether we need to bridge through an Objective-C class.
if (auto classType = TC.getDynamicBridgedThroughObjCClass(DC,
fromBaseType,
toBaseType)) {
// The class we're bridging through must be a subtype of the type we're
// coming from.
addConstraint(ConstraintKind::Subtype, classType, fromBaseType,
getConstraintLocator(locator));
return SolutionKind::Solved;
}
addConstraint(ConstraintKind::Subtype, toBaseType, fromBaseType,
getConstraintLocator(locator));
return SolutionKind::Solved;
}
case CheckedCastKind::DictionaryDowncast:
case CheckedCastKind::DictionaryDowncastBridged: {
Type fromKeyType, fromValueType;
std::tie(fromKeyType, fromValueType) = *isDictionaryType(fromType);
Type toKeyType, toValueType;
std::tie(toKeyType, toValueType) = *isDictionaryType(toType);
// FIXME: Deal with from/to base types that haven't been solved
// down to type variables yet.
// Check whether we need to bridge the key through an Objective-C class.
if (auto bridgedKey = TC.getDynamicBridgedThroughObjCClass(DC,
fromKeyType,
toKeyType)) {
toKeyType = bridgedKey;
}
// Perform subtype check on the possibly-bridged-through key type.
unsigned subFlags = TMF_GenerateConstraints;
auto result = matchTypes(toKeyType, fromKeyType, TypeMatchKind::Subtype,
subFlags, locator);
if (result == SolutionKind::Error)
return result;
// Check whether we need to bridge the value through an Objective-C class.
if (auto bridgedValue = TC.getDynamicBridgedThroughObjCClass(DC,
fromValueType,
toValueType)) {
toValueType = bridgedValue;
}
// Perform subtype check on the possibly-bridged-through value type.
switch (matchTypes(toValueType, fromValueType, TypeMatchKind::Subtype,
subFlags, locator)) {
case SolutionKind::Solved:
return result;
case SolutionKind::Unsolved:
return SolutionKind::Unsolved;
case SolutionKind::Error:
return SolutionKind::Error;
}
}
case CheckedCastKind::SetDowncast:
case CheckedCastKind::SetDowncastBridged: {
auto fromBaseType = getBaseTypeForSetType(fromType.getPointer());
auto toBaseType = getBaseTypeForSetType(toType.getPointer());
// FIXME: Deal with from/to base types that haven't been solved
// down to type variables yet.
// Check whether we need to bridge through an Objective-C class.
if (auto classType = TC.getDynamicBridgedThroughObjCClass(DC,
fromBaseType,
toBaseType)) {
// The class we're bridging through must be a subtype of the type we're
// coming from.
addConstraint(ConstraintKind::Subtype, classType, fromBaseType,
getConstraintLocator(locator));
return SolutionKind::Solved;
}
addConstraint(ConstraintKind::Subtype, toBaseType, fromBaseType,
getConstraintLocator(locator));
return SolutionKind::Solved;
}
case CheckedCastKind::ValueCast: {
// If casting among classes, and there are open
// type variables remaining, introduce a subtype constraint to help resolve
// them.
if (fromType->getClassOrBoundGenericClass()
&& toType->getClassOrBoundGenericClass()
&& (fromType->hasTypeVariable() || toType->hasTypeVariable())) {
addConstraint(ConstraintKind::Subtype, toType, fromType,
getConstraintLocator(locator));
}
return SolutionKind::Solved;
}
case CheckedCastKind::BridgeFromObjectiveC: {
// This existential-to-concrete cast might bridge through an Objective-C
// class type.
Type objCClass = TC.getDynamicBridgedThroughObjCClass(DC,
fromType,
toType);
assert(objCClass && "Type must be bridged");
(void)objCClass;
// Otherwise no constraint is necessary; as long as both objCClass and
// fromType are Objective-C types, they can't have any open type variables,
// and conversion between unrelated classes will be diagnosed in
// typeCheckCheckedCast.
return SolutionKind::Solved;
}
case CheckedCastKind::Coercion:
case CheckedCastKind::Unresolved:
llvm_unreachable("Not a valid result");
}
}
/// Determine whether the given type is the Self type of the protocol.
static bool isProtocolSelf(Type type) {
if (auto genericParam = type->getAs<GenericTypeParamType>())
return genericParam->getDepth() == 0;
return false;
}
/// Determine whether the given type contains a reference to the 'Self' type
/// of a protocol.
static bool containsProtocolSelf(Type type) {
// If the type is not dependent, it doesn't refer to 'Self'.
if (!type->hasTypeParameter())
return false;
return type.findIf([](Type type) -> bool {
return isProtocolSelf(type);
});
}
/// Determine whether the given protocol member's signature prevents
/// it from being used in an existential reference.
static bool isUnavailableInExistential(TypeChecker &tc, ValueDecl *decl) {
Type type = decl->getInterfaceType();
if (!type) // FIXME: deal with broken recursion
return true;
// For a function or constructor, skip the implicit 'this'.
if (auto afd = dyn_cast<AbstractFunctionDecl>(decl)) {
type = type->castTo<AnyFunctionType>()->getResult();
// Allow functions to return Self, but not have Self anywhere in
// their argument types.
for (unsigned i = 1, n = afd->getNumParameterLists(); i != n; ++i) {
// Check whether the input type contains Self anywhere.
auto fnType = type->castTo<AnyFunctionType>();
if (containsProtocolSelf(fnType->getInput()))
return true;
type = fnType->getResult();
}
// Look through one level of optional on the result type.
if (auto valueType = type->getAnyOptionalObjectType())
type = valueType;
if (isProtocolSelf(type) || type->is<DynamicSelfType>())
return false;
return containsProtocolSelf(type);
}
return containsProtocolSelf(type);
}
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyOptionalObjectConstraint(const Constraint &constraint)
{
// Resolve the optional type.
Type optLValueTy = simplifyType(constraint.getFirstType());
Type optTy = optLValueTy->getRValueType();
if (optTy->is<TypeVariableType>()) {
return SolutionKind::Unsolved;
}
// If the base type is not optional, the constraint fails.
Type objectTy = optTy->getAnyOptionalObjectType();
if (!objectTy)
return SolutionKind::Error;
// The object type is an lvalue if the optional was.
if (optLValueTy->is<LValueType>())
objectTy = LValueType::get(objectTy);
// Equate it to the other type in the constraint.
addConstraint(ConstraintKind::Bind, objectTy, constraint.getSecondType(),
constraint.getLocator());
return SolutionKind::Solved;
}
/// If the given type conforms to the RawRepresentable protocol,
/// return its underlying raw type.
static Type getRawRepresentableValueType(TypeChecker &tc, DeclContext *dc,
Type type) {
auto proto = tc.Context.getProtocol(KnownProtocolKind::RawRepresentable);
if (!proto)
return nullptr;
if (type->hasTypeVariable())
return nullptr;
ProtocolConformance *conformance = nullptr;
if (!tc.conformsToProtocol(type, proto, dc,
ConformanceCheckFlags::InExpression, &conformance))
return nullptr;
return tc.getWitnessType(type, proto, conformance, tc.Context.Id_RawValue,
diag::broken_raw_representable_requirement);
}
/// Retrieve the argument labels that are provided for a member
/// reference at the given locator.
static Optional<ArrayRef<Identifier>>
getArgumentLabels(ConstraintSystem &cs, ConstraintLocatorBuilder locator) {
SmallVector<LocatorPathElt, 2> parts;
Expr *anchor = locator.getLocatorParts(parts);
if (!anchor)
return None;
while (!parts.empty()) {
if (parts.back().getKind() == ConstraintLocator::Member ||
parts.back().getKind() == ConstraintLocator::SubscriptMember) {
parts.pop_back();
continue;
}
if (parts.back().getKind() == ConstraintLocator::ApplyFunction) {
if (auto applyExpr = dyn_cast<ApplyExpr>(anchor)) {
anchor = applyExpr->getFn()->getSemanticsProvidingExpr();
}
parts.pop_back();
continue;
}
if (parts.back().getKind() == ConstraintLocator::ConstructorMember) {
// FIXME: Workaround for strange anchor on ConstructorMember locators.
if (auto optionalWrapper = dyn_cast<BindOptionalExpr>(anchor))
anchor = optionalWrapper->getSubExpr();
else if (auto forceWrapper = dyn_cast<ForceValueExpr>(anchor))
anchor = forceWrapper->getSubExpr();
parts.pop_back();
continue;
}
break;
}
if (!parts.empty())
return None;
auto known = cs.ArgumentLabels.find(cs.getConstraintLocator(anchor));
if (known == cs.ArgumentLabels.end())
return None;
return known->second;
}
/// Given a ValueMember, UnresolvedValueMember, or TypeMember constraint,
/// perform a lookup into the specified base type to find a candidate list.
/// The list returned includes the viable candidates as well as the unviable
/// ones (along with reasons why they aren't viable).
MemberLookupResult ConstraintSystem::
performMemberLookup(ConstraintKind constraintKind,
DeclName memberName, Type baseTy,
ConstraintLocator *memberLocator) {
Type baseObjTy = baseTy->getRValueType();
// Dig out the instance type and figure out what members of the instance type
// we are going to see.
bool isMetatype = false;
bool hasInstanceMembers = false;
bool hasInstanceMethods = false;
bool hasStaticMembers = false;
Type instanceTy = baseObjTy;
if (baseObjTy->is<ModuleType>()) {
hasStaticMembers = true;
} else if (auto baseObjMeta = baseObjTy->getAs<AnyMetatypeType>()) {
instanceTy = baseObjMeta->getInstanceType();
isMetatype = true;
if (baseObjMeta->is<ExistentialMetatypeType>()) {
// An instance of an existential metatype is a concrete type conforming
// to the existential, say Self. Instance members of the concrete type
// have type Self -> T -> U, but we don't know what Self is at compile
// time so we cannot refer to them. Static methods are fine, on the other
// hand -- we already know that they do not have Self or associated type
// requirements, since otherwise we would not be able to refer to the
// existential metatype in the first place.
hasStaticMembers = true;
} else if (instanceTy->isExistentialType()) {
// A protocol metatype has instance methods with type P -> T -> U, but
// not instance properties or static members -- the metatype value itself
// doesn't give us a witness so there's no static method to bind.
hasInstanceMethods = true;
} else {
// Metatypes of nominal types and archetypes have instance methods and
// static members, but not instance properties.
// FIXME: partial application of properties
hasInstanceMethods = true;
hasStaticMembers = true;
}
} else {
// Otherwise, we can access all instance members.
hasInstanceMembers = true;
hasInstanceMethods = true;
}
bool isExistential = instanceTy->isExistentialType();
if (instanceTy->is<TypeVariableType>() ||
instanceTy->is<UnresolvedType>()) {
MemberLookupResult result;
result.OverallResult = MemberLookupResult::Unsolved;
return result;
}
// Okay, start building up the result list.
MemberLookupResult result;
result.OverallResult = MemberLookupResult::HasResults;
// If the base type is a tuple type, look for the named or indexed member
// of the tuple.
if (auto baseTuple = baseObjTy->getAs<TupleType>()) {
// Tuples don't have compound-name members.
if (!memberName.isSimpleName())
return result; // No result.
StringRef nameStr = memberName.getBaseName().str();
int fieldIdx = -1;
// Resolve a number reference into the tuple type.
unsigned Value = 0;
if (!nameStr.getAsInteger(10, Value) &&
Value < baseTuple->getNumElements()) {
fieldIdx = Value;
} else {
fieldIdx = baseTuple->getNamedElementId(memberName.getBaseName());
}
if (fieldIdx == -1)
return result; // No result.
// Add an overload set that selects this field.
result.ViableCandidates.push_back(OverloadChoice(baseTy, fieldIdx));
return result;
}
// If we have a simple name, determine whether there are argument
// labels we can use to restrict the set of lookup results.
Optional<ArrayRef<Identifier>> argumentLabels;
if (memberName.isSimpleName()) {
argumentLabels = getArgumentLabels(*this,
ConstraintLocatorBuilder(memberLocator));
// If we're referencing AnyObject and we have argument labels, put
// the argument labels into the name: we don't want to look for
// anything else, because the cost of the general search is so
// high.
if (baseObjTy->isAnyObject() && argumentLabels) {
memberName = DeclName(TC.Context, memberName.getBaseName(),
*argumentLabels);
argumentLabels.reset();
}
}
/// Determine whether the given declaration has compatible argument
/// labels.
auto hasCompatibleArgumentLabels = [&](ValueDecl *decl) -> bool {
if (!argumentLabels)
return true;
auto name = decl->getFullName();
if (name.isSimpleName())
return true;
for (auto argLabel : *argumentLabels) {
if (argLabel.empty())
continue;
if (std::find(name.getArgumentNames().begin(),
name.getArgumentNames().end(),
argLabel) == name.getArgumentNames().end()) {
return false;
}
}
return true;
};
// Handle initializers, they have their own approach to name lookup.
if (memberName.isSimpleName(TC.Context.Id_init)) {
NameLookupOptions lookupOptions = defaultConstructorLookupOptions;
if (isa<AbstractFunctionDecl>(DC))
lookupOptions |= NameLookupFlags::KnownPrivate;
LookupResult ctors = TC.lookupConstructors(DC, baseObjTy, lookupOptions);
if (!ctors)
return result; // No result.
// The constructors are only found on the metatype.
if (!isMetatype)
return result;
TypeBase *favoredType = nullptr;
if (auto anchor = memberLocator->getAnchor()) {
if (auto applyExpr = dyn_cast<ApplyExpr>(anchor)) {
auto argExpr = applyExpr->getArg();
favoredType = getFavoredType(argExpr);
if (!favoredType) {
optimizeConstraints(argExpr);
favoredType = getFavoredType(argExpr);
}
}
}
// Introduce a new overload set.
retry_ctors_after_fail:
bool labelMismatch = false;
for (auto constructor : ctors) {
// If the constructor is invalid, we fail entirely to avoid error cascade.
TC.validateDecl(constructor, true);
if (constructor->isInvalid())
return result.markErrorAlreadyDiagnosed();
// If the argument labels for this result are incompatible with
// the call site, skip it.
if (!hasCompatibleArgumentLabels(constructor)) {
labelMismatch = true;
result.addUnviable(constructor, MemberLookupResult::UR_LabelMismatch);
continue;
}
// If our base is an existential type, we can't make use of any
// constructor whose signature involves associated types.
if (isExistential &&
isUnavailableInExistential(getTypeChecker(), constructor)) {
result.addUnviable(constructor,
MemberLookupResult::UR_UnavailableInExistential);
continue;
}
// If the invocation's argument expression has a favored constraint,
// use that information to determine whether a specific overload for
// the initializer should be favored.
if (favoredType && result.FavoredChoice == ~0U) {
// Only try and favor monomorphic initializers.
if (auto fnTypeWithSelf =
constructor->getType()->getAs<FunctionType>()) {
if (auto fnType =
fnTypeWithSelf->getResult()->getAs<FunctionType>()) {
auto argType = fnType->getInput();
if (auto parenType =
dyn_cast<ParenType>(argType.getPointer())) {
argType = parenType->getUnderlyingType();
}
if (argType->isEqual(favoredType))
result.FavoredChoice = result.ViableCandidates.size();
}
}
}
result.addViable(OverloadChoice(baseTy, constructor,
/*isSpecialized=*/false, *this));
}
// If we rejected some possibilities due to an argument-label
// mismatch and ended up with nothing, try again ignoring the
// labels. This allows us to perform typo correction on the labels.
if (result.ViableCandidates.empty() && labelMismatch &&
shouldAttemptFixes()) {
argumentLabels.reset();
goto retry_ctors_after_fail;
}
// FIXME: Should we look for constructors in bridged types?
return result;
}
// If we want member types only, use member type lookup.
if (constraintKind == ConstraintKind::TypeMember) {
// Types don't have compound names.
// FIXME: Customize diagnostic to mention types and compound names.
if (!memberName.isSimpleName())
return result; // No result.
NameLookupOptions lookupOptions = defaultMemberTypeLookupOptions;
if (isa<AbstractFunctionDecl>(DC))
lookupOptions |= NameLookupFlags::KnownPrivate;
auto lookup = TC.lookupMemberType(DC, baseObjTy, memberName.getBaseName(),
lookupOptions);
// Form the overload set.
for (auto candidate : lookup) {
// If the result is invalid, don't cascade errors.
TC.validateDecl(candidate.first, true);
if (candidate.first->isInvalid())
return result.markErrorAlreadyDiagnosed();
result.addViable(OverloadChoice(baseTy, candidate.first,
/*isSpecialized=*/false));
}
return result;
}
// Look for members within the base.
LookupResult &lookup = lookupMember(baseObjTy, memberName);
// The set of directly accessible types, which is only used when
// we're performing dynamic lookup into an existential type.
bool isDynamicLookup = instanceTy->isAnyObject();
// If the instance type is String bridged to NSString, compute
// the type we'll look in for bridging.
Type bridgedClass;
Type bridgedType;
if (instanceTy->getAnyNominal() == TC.Context.getStringDecl()) {
if (Type classType = TC.getBridgedToObjC(DC, instanceTy)) {
bridgedClass = classType;
bridgedType = isMetatype ? MetatypeType::get(classType) : classType;
}
}
bool labelMismatch = false;
// Local function that adds the given declaration if it is a
// reasonable choice.
auto addChoice = [&](ValueDecl *cand, bool isBridged,
bool isUnwrappedOptional) {
// If the result is invalid, skip it.
TC.validateDecl(cand, true);
if (cand->isInvalid()) {
result.markErrorAlreadyDiagnosed();
return;
}
// If the argument labels for this result are incompatible with
// the call site, skip it.
if (!hasCompatibleArgumentLabels(cand)) {
labelMismatch = true;
result.addUnviable(cand, MemberLookupResult::UR_LabelMismatch);
return;
}
// If our base is an existential type, we can't make use of any
// member whose signature involves associated types.
if (isExistential && isUnavailableInExistential(getTypeChecker(), cand)) {
result.addUnviable(cand, MemberLookupResult::UR_UnavailableInExistential);
return;
}
// See if we have an instance method, instance member or static method,
// and check if it can be accessed on our base type.
if (cand->isInstanceMember()) {
if ((isa<FuncDecl>(cand) && !hasInstanceMethods) ||
(!isa<FuncDecl>(cand) && !hasInstanceMembers)) {
result.addUnviable(cand, MemberLookupResult::UR_InstanceMemberOnType);
return;
}
} else {
if (!hasStaticMembers) {
result.addUnviable(cand, MemberLookupResult::UR_TypeMemberOnInstance);
return;
}
}
// If we have an rvalue base, make sure that the result isn't 'mutating'
// (only valid on lvalues).
if (!isMetatype &&
!baseTy->is<LValueType>() && cand->isInstanceMember()) {
if (auto *FD = dyn_cast<FuncDecl>(cand))
if (FD->isMutating()) {
result.addUnviable(cand,
MemberLookupResult::UR_MutatingMemberOnRValue);
return;
}
// Subscripts and computed properties are ok on rvalues so long
// as the getter is nonmutating.
if (auto storage = dyn_cast<AbstractStorageDecl>(cand)) {
if (storage->isGetterMutating()) {
result.addUnviable(cand,
MemberLookupResult::UR_MutatingGetterOnRValue);
return;
}
}
}
// If the result's type contains delayed members, we need to force them now.
if (auto NT = dyn_cast<NominalType>(cand->getType().getPointer())) {
if (auto *NTD = dyn_cast<NominalTypeDecl>(NT->getDecl())) {
TC.forceExternalDeclMembers(NTD);
}
}
// If we're looking into an existential type, check whether this
// result was found via dynamic lookup.
if (isDynamicLookup) {
assert(cand->getDeclContext()->isTypeContext() && "Dynamic lookup bug");
// We found this declaration via dynamic lookup, record it as such.
result.addViable(OverloadChoice::getDeclViaDynamic(baseTy, cand));
return;
}
// If we have a bridged type, we found this declaration via bridging.
if (isBridged) {
result.addViable(OverloadChoice::getDeclViaBridge(bridgedType, cand));
return;
}
// If we got the choice by unwrapping an optional type, unwrap the base
// type.
Type ovlBaseTy = baseTy;
if (isUnwrappedOptional) {
ovlBaseTy = MetatypeType::get(baseTy->castTo<MetatypeType>()
->getInstanceType()
->getAnyOptionalObjectType());
result.addViable(OverloadChoice::getDeclViaUnwrappedOptional(ovlBaseTy,
cand));
} else {
result.addViable(OverloadChoice(ovlBaseTy, cand,
/*isSpecialized=*/false, *this));
}
};
// Add all results from this lookup.
retry_after_fail:
labelMismatch = false;
for (auto result : lookup)
addChoice(result, /*isBridged=*/false, /*isUnwrappedOptional=*/false);
// If the instance type is a bridged to an Objective-C type, perform
// a lookup into that Objective-C type.
if (bridgedType) {
LookupResult &bridgedLookup = lookupMember(bridgedClass, memberName);
Module *foundationModule = nullptr;
for (auto result : bridgedLookup) {
// Ignore results from the Objective-C "Foundation"
// module. Those core APIs are explicitly provided by the
// Foundation module overlay.
auto module = result->getModuleContext();
if (foundationModule) {
if (module == foundationModule)
continue;
} else if (ClangModuleUnit::hasClangModule(module) &&
module->getName().str() == "Foundation") {
// Cache the foundation module name so we don't need to look
// for it again.
foundationModule = module;
continue;
}
addChoice(result, /*isBridged=*/true, /*isUnwrappedOptional=*/false);
}
}
// If we're looking into a metatype for an unresolved member lookup, look
// through optional types.
//
// FIXME: The short-circuit here is lame.
if (result.ViableCandidates.empty() && isMetatype &&
constraintKind == ConstraintKind::UnresolvedValueMember) {
if (auto objectType = instanceTy->getAnyOptionalObjectType()) {
LookupResult &optionalLookup = lookupMember(MetatypeType::get(objectType),
memberName);
for (auto result : optionalLookup)
addChoice(result, /*bridged*/false, /*isUnwrappedOptional=*/true);
}
}
// If we rejected some possibilities due to an argument-label
// mismatch and ended up with nothing, try again ignoring the
// labels. This allows us to perform typo correction on the labels.
if (result.ViableCandidates.empty() && labelMismatch && shouldAttemptFixes()){
argumentLabels.reset();
goto retry_after_fail;
}
return result;
}
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyMemberConstraint(const Constraint &constraint) {
// Resolve the base type, if we can. If we can't resolve the base type,
// then we can't solve this constraint.
Type baseTy = simplifyType(constraint.getFirstType());
Type baseObjTy = baseTy->getRValueType();
// Try to look through ImplicitlyUnwrappedOptional<T>; the result is
// always an l-value if the input was.
if (auto objTy = lookThroughImplicitlyUnwrappedOptionalType(baseObjTy)) {
increaseScore(SK_ForceUnchecked);
baseObjTy = objTy;
if (baseTy->is<LValueType>())
baseTy = LValueType::get(objTy);
else
baseTy = objTy;
}
MemberLookupResult result =
performMemberLookup(constraint.getKind(), constraint.getMember(),
baseTy, constraint.getLocator());
DeclName name = constraint.getMember();
Type memberTy = constraint.getSecondType();
switch (result.OverallResult) {
case MemberLookupResult::Unsolved:
return SolutionKind::Unsolved;
case MemberLookupResult::ErrorAlreadyDiagnosed:
return SolutionKind::Error;
case MemberLookupResult::HasResults:
// Keep going!
break;
}
// If we found viable candidates, then we're done!
if (!result.ViableCandidates.empty()) {
addOverloadSet(memberTy, result.ViableCandidates, constraint.getLocator(),
result.getFavoredChoice());
return SolutionKind::Solved;
}
// If we found some unviable results, then fail, but without recovery.
if (!result.UnviableCandidates.empty())
return SolutionKind::Error;
// If the lookup found no hits at all (either viable or unviable), diagnose it
// as such and try to recover in various ways.
if (constraint.getKind() == ConstraintKind::TypeMember) {
// If the base type was an optional, try to look through it.
if (shouldAttemptFixes() && baseObjTy->getOptionalObjectType()) {
// Note the fix.
if (recordFix(FixKind::ForceOptional, constraint.getLocator()))
return SolutionKind::Error;
// Look through one level of optional.
addConstraint(Constraint::create(*this, ConstraintKind::TypeMember,
baseObjTy->getOptionalObjectType(),
constraint.getSecondType(),
constraint.getMember(),
constraint.getLocator()));
return SolutionKind::Solved;
}
return SolutionKind::Error;
}
auto instanceTy = baseObjTy;
if (auto MTT = instanceTy->getAs<MetatypeType>())
instanceTy = MTT->getInstanceType();
// Value member lookup has some hacks too.
Type rawValueType;
if (shouldAttemptFixes() && name == TC.Context.Id_fromRaw &&
(rawValueType = getRawRepresentableValueType(TC, DC, instanceTy))) {
// Replace a reference to ".fromRaw" with a reference to init(rawValue:).
// FIXME: This is temporary.
// Record this fix.
if (recordFix(FixKind::FromRawToInit, constraint.getLocator()))
return SolutionKind::Error;
// Form the type that "fromRaw" would have had and bind the
// member type to it.
Type fromRawType = FunctionType::get(ParenType::get(TC.Context,
rawValueType),
OptionalType::get(instanceTy));
addConstraint(ConstraintKind::Bind, memberTy, fromRawType,
constraint.getLocator());
return SolutionKind::Solved;
}
if (shouldAttemptFixes() && name == TC.Context.Id_toRaw &&
(rawValueType = getRawRepresentableValueType(TC, DC, instanceTy))) {
// Replace a call to "toRaw" with a reference to rawValue.
// FIXME: This is temporary.
// Record this fix.
if (recordFix(FixKind::ToRawToRawValue, constraint.getLocator()))
return SolutionKind::Error;
// Form the type that "toRaw" would have had and bind the member
// type to it.
Type toRawType = FunctionType::get(TupleType::getEmpty(TC.Context),
rawValueType);
addConstraint(ConstraintKind::Bind, memberTy, toRawType,
constraint.getLocator());
return SolutionKind::Solved;
}
if (shouldAttemptFixes() && name.isSimpleName("allZeros") &&
(rawValueType = getRawRepresentableValueType(TC, DC, instanceTy))) {
// Replace a reference to "X.allZeros" with a reference to X().
// FIXME: This is temporary.
// Record this fix.
if (recordFix(FixKind::AllZerosToInit, constraint.getLocator()))
return SolutionKind::Error;
// Form the type that "allZeros" would have had and bind the
// member type to it.
addConstraint(ConstraintKind::Bind, memberTy, rawValueType,
constraint.getLocator());
return SolutionKind::Solved;
}
if (shouldAttemptFixes() && baseObjTy->getOptionalObjectType()) {
// If the base type was an optional, look through it.
// Note the fix.
if (recordFix(FixKind::ForceOptional, constraint.getLocator()))
return SolutionKind::Error;
// Look through one level of optional.
addValueMemberConstraint(baseObjTy->getOptionalObjectType(),
constraint.getMember(),
constraint.getSecondType(),
constraint.getLocator());
return SolutionKind::Solved;
}
return SolutionKind::Error;
}
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyArchetypeConstraint(const Constraint &constraint) {
// Resolve the base type, if we can. If we can't resolve the base type,
// then we can't solve this constraint.
Type baseTy = constraint.getFirstType()->getRValueType();
if (auto tv = dyn_cast<TypeVariableType>(baseTy.getPointer())) {
auto fixed = getFixedType(tv);
if (!fixed)
return SolutionKind::Unsolved;
// Continue with the fixed type.
baseTy = fixed->getRValueType();
}
if (baseTy->is<ArchetypeType>())
return SolutionKind::Solved;
return SolutionKind::Error;
}
/// Simplify the given type for use in a type property constraint.
static Type simplifyForTypePropertyConstraint(ConstraintSystem &cs, Type type) {
if (auto tv = type->getAs<TypeVariableType>()) {
auto fixed = cs.getFixedType(tv);
if (!fixed)
return Type();
// Continue with the fixed type.
type = fixed;
// Look through parentheses.
while (auto paren = dyn_cast<ParenType>(type.getPointer()))
type = paren->getUnderlyingType();
}
return type;
}
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyClassConstraint(const Constraint &constraint){
auto baseTy = simplifyForTypePropertyConstraint(*this,
constraint.getFirstType());
if (!baseTy)
return SolutionKind::Unsolved;
if (baseTy->getClassOrBoundGenericClass())
return SolutionKind::Solved;
if (auto archetype = baseTy->getAs<ArchetypeType>()) {
if (archetype->requiresClass())
return SolutionKind::Solved;
}
return SolutionKind::Error;
}
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyBridgedToObjectiveCConstraint(
const Constraint &constraint)
{
auto baseTy = simplifyForTypePropertyConstraint(*this,
constraint.getFirstType());
if (!baseTy)
return SolutionKind::Unsolved;
if (TC.getBridgedToObjC(DC, baseTy)) {
increaseScore(SK_UserConversion);
return SolutionKind::Solved;
}
// Record this failure.
recordFailure(constraint.getLocator(),
Failure::IsNotBridgedToObjectiveC,
baseTy);
return SolutionKind::Error;
}
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyDefaultableConstraint(const Constraint &constraint) {
// Leave the constraint around if the first variable is still opaque.
auto baseTy = simplifyForTypePropertyConstraint(*this,
constraint.getFirstType());
if (!baseTy)
return SolutionKind::Unsolved;
// Otherwise, any type is fine.
return SolutionKind::Solved;
}
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyDynamicTypeOfConstraint(const Constraint &constraint) {
// Solve forward.
TypeVariableType *typeVar2;
Type type2 = getFixedTypeRecursive(constraint.getSecondType(), typeVar2,
/*wantRValue=*/ true);
if (!typeVar2) {
Type dynamicType2;
if (type2->isAnyExistentialType()) {
dynamicType2 = ExistentialMetatypeType::get(type2);
} else {
dynamicType2 = MetatypeType::get(type2);
}
return matchTypes(constraint.getFirstType(), dynamicType2,
TypeMatchKind::BindType, TMF_GenerateConstraints,
constraint.getLocator());
}
// Okay, can't solve forward. See what we can do backwards.
TypeVariableType *typeVar1;
Type type1 = getFixedTypeRecursive(constraint.getFirstType(), typeVar1, true);
// If we have an existential metatype, that's good enough to solve
// the constraint.
if (auto metatype1 = type1->getAs<ExistentialMetatypeType>())
return matchTypes(metatype1->getInstanceType(), type2,
TypeMatchKind::BindType,
TMF_GenerateConstraints, constraint.getLocator());
// If we have a normal metatype, we can't solve backwards unless we
// know what kind of object it is.
if (auto metatype1 = type1->getAs<MetatypeType>()) {
TypeVariableType *instanceTypeVar1;
Type instanceType1 = getFixedTypeRecursive(metatype1->getInstanceType(),
instanceTypeVar1, true);
if (!instanceTypeVar1) {
return matchTypes(instanceType1, type2,
TypeMatchKind::BindType,
TMF_GenerateConstraints, constraint.getLocator());
}
// If it's definitely not either kind of metatype, then we can
// report failure right away.
} else if (!typeVar1) {
return SolutionKind::Error;
}
return SolutionKind::Unsolved;
}
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyApplicableFnConstraint(const Constraint &constraint) {
// By construction, the left hand side is a type that looks like the
// following: $T1 -> $T2.
Type type1 = constraint.getFirstType();
assert(type1->is<FunctionType>());
// Drill down to the concrete type on the right hand side.
TypeVariableType *typeVar2;
Type type2 = getFixedTypeRecursive(constraint.getSecondType(), typeVar2,
/*wantRValue=*/true);
auto desugar2 = type2->getDesugaredType();
// Try to look through ImplicitlyUnwrappedOptional<T>: the result is always an
// r-value.
if (auto objTy = lookThroughImplicitlyUnwrappedOptionalType(desugar2)) {
type2 = objTy;
desugar2 = type2->getDesugaredType();
}
// Force the right-hand side to be an rvalue.
unsigned flags = TMF_GenerateConstraints;
// If the types are obviously equivalent, we're done.
if (type1.getPointer() == desugar2)
return SolutionKind::Solved;
// If right-hand side is a type variable, the constraint is unsolved.
if (typeVar2)
return SolutionKind::Unsolved;
// Strip the 'ApplyFunction' off the locator.
// FIXME: Perhaps ApplyFunction can go away entirely?
ConstraintLocatorBuilder locator = constraint.getLocator();
SmallVector<LocatorPathElt, 2> parts;
Expr *anchor = locator.getLocatorParts(parts);
assert(!parts.empty() && "Nonsensical applicable-function locator");
assert(parts.back().getKind() == ConstraintLocator::ApplyFunction);
assert(parts.back().getNewSummaryFlags() == 0);
parts.pop_back();
ConstraintLocatorBuilder outerLocator =
getConstraintLocator(anchor, parts, locator.getSummaryFlags());
retry:
// For a function, bind the output and convert the argument to the input.
auto func1 = type1->castTo<FunctionType>();
if (desugar2->getKind() == TypeKind::Function) {
auto func2 = cast<FunctionType>(desugar2);
// If this application is part of an operator, then we allow an implicit
// lvalue to be compatible with inout arguments. This is used by
// assignment operators.
TypeMatchKind ArgConv = TypeMatchKind::ArgumentTupleConversion;
if (isa<PrefixUnaryExpr>(anchor) || isa<PostfixUnaryExpr>(anchor) ||
isa<BinaryExpr>(anchor))
ArgConv = TypeMatchKind::OperatorArgumentTupleConversion;
// The argument type must be convertible to the input type.
if (matchTypes(func1->getInput(), func2->getInput(),
ArgConv, flags,
outerLocator.withPathElement(
ConstraintLocator::ApplyArgument))
== SolutionKind::Error)
return SolutionKind::Error;
// The result types are equivalent.
if (matchTypes(func1->getResult(), func2->getResult(),
TypeMatchKind::BindType,
flags,
locator.withPathElement(ConstraintLocator::FunctionResult))
== SolutionKind::Error)
return SolutionKind::Error;
// If our type constraints is for a FunctionType, move over the @noescape
// flag.
if (func1->isNoEscape() && !func2->isNoEscape()) {
auto &extraExtInfo = extraFunctionAttrs[func2];
extraExtInfo = extraExtInfo.withNoEscape();
}
return SolutionKind::Solved;
}
// For a metatype, perform a construction.
if (auto meta2 = dyn_cast<AnyMetatypeType>(desugar2)) {
// Construct the instance from the input arguments.
return simplifyConstructionConstraint(meta2->getInstanceType(), func1,
flags,
getConstraintLocator(outerLocator));
}
if (!shouldAttemptFixes())
return SolutionKind::Error;
// If we're coming from an optional type, unwrap the optional and try again.
if (auto objectType2 = desugar2->getOptionalObjectType()) {
if (recordFix(FixKind::ForceOptional, getConstraintLocator(locator)))
return SolutionKind::Error;
type2 = objectType2;
desugar2 = type2->getDesugaredType();
goto retry;
}
// If this is a '()' call, drop the call.
if (func1->getInput()->isEqual(TupleType::getEmpty(getASTContext()))) {
// We don't bother with a 'None' case, because at this point we won't get
// a better diagnostic from that case.
if (recordFix(FixKind::RemoveNullaryCall, getConstraintLocator(locator)))
return SolutionKind::Error;
return matchTypes(func1->getResult(), type2,
TypeMatchKind::BindType,
flags | TMF_ApplyingFix | TMF_GenerateConstraints,
locator.withPathElement(
ConstraintLocator::FunctionResult));
}
return SolutionKind::Error;
}
/// \brief Retrieve the type-matching kind corresponding to the given
/// constraint kind.
static TypeMatchKind getTypeMatchKind(ConstraintKind kind) {
switch (kind) {
case ConstraintKind::Bind: return TypeMatchKind::BindType;
case ConstraintKind::Equal: return TypeMatchKind::SameType;
case ConstraintKind::BindParam: return TypeMatchKind::BindParamType;
case ConstraintKind::Subtype: return TypeMatchKind::Subtype;
case ConstraintKind::Conversion: return TypeMatchKind::Conversion;
case ConstraintKind::ExplicitConversion:
return TypeMatchKind::ExplicitConversion;
case ConstraintKind::ArgumentConversion:
return TypeMatchKind::ArgumentConversion;
case ConstraintKind::ArgumentTupleConversion:
return TypeMatchKind::ArgumentTupleConversion;
case ConstraintKind::OperatorArgumentTupleConversion:
return TypeMatchKind::OperatorArgumentTupleConversion;
case ConstraintKind::OperatorArgumentConversion:
return TypeMatchKind::OperatorArgumentConversion;
case ConstraintKind::ApplicableFunction:
llvm_unreachable("ApplicableFunction constraints don't involve "
"type matches");
case ConstraintKind::DynamicTypeOf:
llvm_unreachable("DynamicTypeOf constraints don't involve type matches");
case ConstraintKind::BindOverload:
llvm_unreachable("Overload binding constraints don't involve type matches");
case ConstraintKind::ConformsTo:
case ConstraintKind::SelfObjectOfProtocol:
llvm_unreachable("Conformance constraints don't involve type matches");
case ConstraintKind::CheckedCast:
llvm_unreachable("Checked cast constraints don't involve type matches");
case ConstraintKind::ValueMember:
case ConstraintKind::UnresolvedValueMember:
case ConstraintKind::TypeMember:
llvm_unreachable("Member constraints don't involve type matches");
case ConstraintKind::OptionalObject:
llvm_unreachable("optional object constraints don't involve type matches");
case ConstraintKind::Archetype:
case ConstraintKind::Class:
case ConstraintKind::BridgedToObjectiveC:
case ConstraintKind::Defaultable:
llvm_unreachable("Type properties don't involve type matches");
case ConstraintKind::Disjunction:
llvm_unreachable("Con/disjunction constraints don't involve type matches");
}
}
Type ConstraintSystem::getBaseTypeForArrayType(TypeBase *type) {
type = type->lookThroughAllAnyOptionalTypes().getPointer();
if (auto bound = type->getAs<BoundGenericStructType>()) {
if (bound->getDecl() == getASTContext().getArrayDecl()) {
return bound->getGenericArgs()[0];
}
}
type->dump();
llvm_unreachable("attempted to extract a base type from a non-array type");
}
Type ConstraintSystem::getBaseTypeForSetType(TypeBase *type) {
type = type->lookThroughAllAnyOptionalTypes().getPointer();
if (auto bound = type->getAs<BoundGenericStructType>()) {
if (bound->getDecl() == getASTContext().getSetDecl()) {
return bound->getGenericArgs()[0];
}
}
type->dump();
llvm_unreachable("attempted to extract a base type from a non-set type");
}
static Type getBaseTypeForPointer(ConstraintSystem &cs, TypeBase *type) {
auto bgt = type->castTo<BoundGenericType>();
assert((bgt->getDecl() == cs.getASTContext().getUnsafeMutablePointerDecl()
|| bgt->getDecl() == cs.getASTContext().getUnsafePointerDecl()
|| bgt->getDecl()
== cs.getASTContext().getAutoreleasingUnsafeMutablePointerDecl())
&& "conversion is not to a pointer type");
return bgt->getGenericArgs()[0];
}
/// Given that we have a conversion constraint between two types, and
/// that the given constraint-reduction rule applies between them at
/// the top level, apply it and generate any necessary recursive
/// constraints.
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyRestrictedConstraint(ConversionRestrictionKind restriction,
Type type1, Type type2,
TypeMatchKind matchKind,
unsigned flags,
ConstraintLocatorBuilder locator) {
// Add to the score based on context.
auto addContextualScore = [&] {
// Okay, we need to perform one or more conversions. If this
// conversion will cause a function conversion, score it as worse.
// This induces conversions to occur within closures instead of
// outside of them wherever possible.
if (locator.isFunctionConversion()) {
increaseScore(SK_FunctionConversion);
}
};
// We'll apply user conversions for operator arguments at the application
// site.
if (matchKind == TypeMatchKind::OperatorArgumentConversion) {
flags |= TMF_ApplyingOperatorParameter;
}
unsigned subFlags = flags | TMF_GenerateConstraints;
switch (restriction) {
// for $< in { <, <c, <oc }:
// T_i $< U_i ===> (T_i...) $< (U_i...)
case ConversionRestrictionKind::TupleToTuple:
return matchTupleTypes(type1->castTo<TupleType>(),
type2->castTo<TupleType>(),
matchKind, subFlags, locator);
// T <c U ===> T <c (U)
case ConversionRestrictionKind::ScalarToTuple:
return matchScalarToTupleTypes(type1,
type2->castTo<TupleType>(),
matchKind, subFlags, locator);
// for $< in { <, <c, <oc }:
// T $< U ===> (T) $< U
case ConversionRestrictionKind::TupleToScalar:
return matchTupleToScalarTypes(type1->castTo<TupleType>(),
type2,
matchKind, subFlags, locator);
case ConversionRestrictionKind::DeepEquality:
return matchDeepEqualityTypes(type1, type2, locator);
case ConversionRestrictionKind::Superclass:
addContextualScore();
return matchSuperclassTypes(type1, type2, matchKind, subFlags, locator);
case ConversionRestrictionKind::LValueToRValue:
return matchTypes(type1->getRValueType(), type2,
matchKind, subFlags, locator);
// for $< in { <, <c, <oc }:
// T $< U, U : P_i ===> T $< protocol<P_i...>
case ConversionRestrictionKind::Existential:
addContextualScore();
return matchExistentialTypes(type1, type2,
ConstraintKind::SelfObjectOfProtocol,
subFlags, locator);
// for $< in { <, <c, <oc }:
// for T protocol,
// T : S ===> T.Protocol $< S.Type
// else,
// T : S ===> T.Type $< S.Type
case ConversionRestrictionKind::MetatypeToExistentialMetatype:
addContextualScore();
return matchExistentialTypes(type1, type2,
ConstraintKind::ConformsTo,
subFlags, locator);
// for $< in { <, <c, <oc }:
// T $< U ===> T $< U?
case ConversionRestrictionKind::ValueToOptional: {
addContextualScore();
increaseScore(SK_ValueToOptional);
assert(matchKind >= TypeMatchKind::Subtype);
auto generic2 = type2->castTo<BoundGenericType>();
assert(generic2->getDecl()->classifyAsOptionalType());
return matchTypes(type1, generic2->getGenericArgs()[0],
matchKind, (subFlags | TMF_UnwrappingOptional), locator);
}
// for $< in { <, <c, <oc }:
// T $< U ===> T? $< U?
// T $< U ===> T! $< U!
// T $< U ===> T! $< U?
// also:
// T <c U ===> T? <c U!
case ConversionRestrictionKind::OptionalToImplicitlyUnwrappedOptional:
case ConversionRestrictionKind::ImplicitlyUnwrappedOptionalToOptional:
case ConversionRestrictionKind::OptionalToOptional: {
addContextualScore();
assert(matchKind >= TypeMatchKind::Subtype);
auto generic1 = type1->castTo<BoundGenericType>();
auto generic2 = type2->castTo<BoundGenericType>();
assert(generic1->getDecl()->classifyAsOptionalType());
assert(generic2->getDecl()->classifyAsOptionalType());
return matchTypes(generic1->getGenericArgs()[0],
generic2->getGenericArgs()[0],
matchKind, subFlags,
locator.withPathElement(
LocatorPathElt::getGenericArgument(0)));
}
// T <c U ===> T! <c U
//
// We don't want to allow this after user-defined conversions:
// - it gets really complex for users to understand why there's
// a dereference in their code
// - it would allow nil to be coercible to a non-optional type
// Fortunately, user-defined conversions only allow subtype
// conversions on their results.
case ConversionRestrictionKind::ForceUnchecked: {
addContextualScore();
assert(matchKind >= TypeMatchKind::Conversion);
auto boundGenericType1 = type1->castTo<BoundGenericType>();
assert(boundGenericType1->getDecl()->classifyAsOptionalType()
== OTK_ImplicitlyUnwrappedOptional);
assert(boundGenericType1->getGenericArgs().size() == 1);
Type valueType1 = boundGenericType1->getGenericArgs()[0];
increaseScore(SK_ForceUnchecked);
return matchTypes(valueType1, type2,
matchKind, subFlags,
locator.withPathElement(
LocatorPathElt::getGenericArgument(0)));
}
case ConversionRestrictionKind::ClassMetatypeToAnyObject:
case ConversionRestrictionKind::ExistentialMetatypeToAnyObject:
case ConversionRestrictionKind::ProtocolMetatypeToProtocolClass: {
// Nothing more to solve.
addContextualScore();
return SolutionKind::Solved;
}
// T <p U ===> T[] <a UnsafeMutablePointer<U>
case ConversionRestrictionKind::ArrayToPointer: {
addContextualScore();
auto obj1 = type1;
// Unwrap an inout type.
if (auto inout1 = obj1->getAs<InOutType>()) {
obj1 = inout1->getObjectType();
}
TypeVariableType *tv1;
obj1 = getFixedTypeRecursive(obj1, tv1, false, false);
auto t1 = obj1->getDesugaredType();
auto t2 = type2->getDesugaredType();
auto baseType1 = getBaseTypeForArrayType(t1);
auto baseType2 = getBaseTypeForPointer(*this, t2);
return matchTypes(baseType1, baseType2,
TypeMatchKind::BindToPointerType,
subFlags, locator);
}
// String ===> UnsafePointer<[U]Int8>
case ConversionRestrictionKind::StringToPointer: {
addContextualScore();
auto baseType2 = getBaseTypeForPointer(*this, type2->getDesugaredType());
// The pointer element type must be void or a byte-sized type.
// TODO: Handle different encodings based on pointer element type, such as
// UTF16 for [U]Int16 or UTF32 for [U]Int32. For now we only interop with
// Int8 pointers using UTF8 encoding.
TypeVariableType *btv2 = nullptr;
baseType2 = getFixedTypeRecursive(baseType2, btv2, false, false);
// If we haven't resolved the element type, generate constraints.
if (btv2) {
if (flags & TMF_GenerateConstraints) {
auto int8Con = Constraint::create(*this, ConstraintKind::Bind,
btv2, TC.getInt8Type(DC),
DeclName(),
getConstraintLocator(locator));
auto uint8Con = Constraint::create(*this, ConstraintKind::Bind,
btv2, TC.getUInt8Type(DC),
DeclName(),
getConstraintLocator(locator));
auto voidCon = Constraint::create(*this, ConstraintKind::Bind,
btv2, TC.Context.TheEmptyTupleType,
DeclName(),
getConstraintLocator(locator));
Constraint *disjunctionChoices[] = {int8Con, uint8Con, voidCon};
auto disjunction = Constraint::createDisjunction(*this,
disjunctionChoices,
getConstraintLocator(locator));
addConstraint(disjunction);
return SolutionKind::Solved;
}
return SolutionKind::Unsolved;
}
if (!isStringCompatiblePointerBaseType(TC, DC, baseType2)) {
return SolutionKind::Unsolved;
}
return SolutionKind::Solved;
}
// T <p U ===> inout T <a UnsafeMutablePointer<U>
case ConversionRestrictionKind::InoutToPointer: {
addContextualScore();
auto t2 = type2->getDesugaredType();
auto baseType1 = type1->getInOutObjectType();
auto baseType2 = getBaseTypeForPointer(*this, t2);
// Set up the disjunction for the array or scalar cases.
return matchTypes(baseType1, baseType2,
TypeMatchKind::BindToPointerType,
subFlags, locator);
}
// T <p U ===> UnsafeMutablePointer<T> <a UnsafeMutablePointer<U>
case ConversionRestrictionKind::PointerToPointer: {
auto t1 = type1->getDesugaredType();
auto t2 = type2->getDesugaredType();
Type baseType1 = getBaseTypeForPointer(*this, t1);
Type baseType2 = getBaseTypeForPointer(*this, t2);
return matchTypes(baseType1, baseType2,
TypeMatchKind::BindToPointerType,
subFlags, locator);
}
// T < U or T is bridged to V where V < U ===> Array<T> <c Array<U>
case ConversionRestrictionKind::ArrayUpcast: {
auto t1 = type1->getDesugaredType();
auto t2 = type2->getDesugaredType();
Type baseType1 = getBaseTypeForArrayType(t1);
Type baseType2 = getBaseTypeForArrayType(t2);
// Look through type variables in the first element type; we need to know
// it's structure before we can decide whether this can be an array upcast.
TypeVariableType *baseTypeVar1;
baseType1 = getFixedTypeRecursive(baseType1, baseTypeVar1, false, false);
if (baseTypeVar1) {
if (flags & TMF_GenerateConstraints) {
addConstraint(
Constraint::createRestricted(*this, getConstraintKind(matchKind),
restriction, type1, type2,
getConstraintLocator(locator)));
return SolutionKind::Solved;
}
return SolutionKind::Unsolved;
}
bool isSimpleUpcast = baseType1->isBridgeableObjectType();
if (isSimpleUpcast) {
increaseScore(SK_CollectionUpcastConversion);
} else {
// Check whether this is a bridging upcast.
Type bridgedType1 = TC.getBridgedToObjC(DC, baseType1);
if (!bridgedType1) {
// FIXME: Record error.
return SolutionKind::Error;
}
// Replace the base type so we perform the appropriate subtype check.
baseType1 = bridgedType1;
increaseScore(SK_CollectionBridgedConversion);
}
addContextualScore();
assert(matchKind >= TypeMatchKind::Conversion);
return matchTypes(baseType1,
baseType2,
TypeMatchKind::Subtype,
subFlags,
locator);
}
// K1 < K2 && V1 < V2 || K1 bridges to K2 && V1 bridges to V2 ===>
// Dictionary<K1, V1> <c Dictionary<K2, V2>
case ConversionRestrictionKind::DictionaryUpcast: {
auto t1 = type1->getDesugaredType();
Type key1, value1;
std::tie(key1, value1) = *isDictionaryType(t1);
auto t2 = type2->getDesugaredType();
Type key2, value2;
std::tie(key2, value2) = *isDictionaryType(t2);
// Look through type variables in the first key and value type; we
// need to know their structure before we can decide whether this
// can be an upcast.
TypeVariableType *keyTypeVar1 = nullptr;
TypeVariableType *valueTypeVar1 = nullptr;
key1 = getFixedTypeRecursive(key1, keyTypeVar1, false, false);
if (!keyTypeVar1) {
value1 = getFixedTypeRecursive(value1, valueTypeVar1, false, false);
}
if (keyTypeVar1 || valueTypeVar1) {
if (flags & TMF_GenerateConstraints) {
addConstraint(
Constraint::createRestricted(*this, getConstraintKind(matchKind),
restriction, type1, type2,
getConstraintLocator(locator)));
return SolutionKind::Solved;
}
return SolutionKind::Unsolved;
}
// If both the first key and value types are bridgeable object
// types, this can only be an upcast.
bool isUpcast = key1->isBridgeableObjectType() &&
value1->isBridgeableObjectType();
if (isUpcast) {
increaseScore(SK_CollectionUpcastConversion);
} else {
// This might be a bridged upcast.
Type bridgedKey1 = TC.getBridgedToObjC(DC, key1);
Type bridgedValue1;
if (bridgedKey1) {
bridgedValue1 = TC.getBridgedToObjC(DC, value1);
}
// Both the key and value types need to be bridged.
if (!bridgedKey1 || !bridgedValue1) {
// FIXME: Record failure.
return SolutionKind::Error;
}
// Look through the destination key and value types. We need
// their structure to determine whether we'll be bridging or
// upcasting the key and value.
TypeVariableType *keyTypeVar2 = nullptr;
TypeVariableType *valueTypeVar2 = nullptr;
key2 = getFixedTypeRecursive(key2, keyTypeVar2, false, false);
if (!keyTypeVar2) {
value2 = getFixedTypeRecursive(value2, valueTypeVar2, false, false);
}
// If either the destination key or value type is a type
// variable, we can't simplify this now.
if (keyTypeVar2 || valueTypeVar2) {
if (flags & TMF_GenerateConstraints) {
addConstraint(
Constraint::createRestricted(*this, getConstraintKind(matchKind),
restriction, type1, type2,
getConstraintLocator(locator)));
return SolutionKind::Solved;
}
return SolutionKind::Unsolved;
}
// This can be a bridging upcast.
if (key2->isBridgeableObjectType())
key1 = bridgedKey1;
if (value2->isBridgeableObjectType())
value1 = bridgedValue1;
increaseScore(SK_CollectionBridgedConversion);
}
addContextualScore();
assert(matchKind >= TypeMatchKind::Conversion);
// The source key and value types must be subtypes of the destination
// key and value types, respectively.
auto result = matchTypes(key1, key2, TypeMatchKind::Subtype, subFlags,
locator);
if (result == SolutionKind::Error)
return result;
switch (matchTypes(value1, value2, TypeMatchKind::Subtype, subFlags,
locator)) {
case SolutionKind::Solved:
return result;
case SolutionKind::Unsolved:
return SolutionKind::Unsolved;
case SolutionKind::Error:
return SolutionKind::Error;
}
}
// T1 < T2 || T1 bridges to T2 ===> Set<T1> <c Set<T2>
case ConversionRestrictionKind::SetUpcast: {
auto t1 = type1->getDesugaredType();
Type baseType1 = getBaseTypeForSetType(t1);
auto t2 = type2->getDesugaredType();
Type baseType2 = getBaseTypeForSetType(t2);
// Look through type variables in the first base type; we need to know
// their structure before we can decide whether this can be an upcast.
TypeVariableType *baseTypeVar1 = nullptr;
baseType1 = getFixedTypeRecursive(baseType1, baseTypeVar1, false, false);
if (baseTypeVar1) {
if (flags & TMF_GenerateConstraints) {
addConstraint(
Constraint::createRestricted(*this, getConstraintKind(matchKind),
restriction, type1, type2,
getConstraintLocator(locator)));
return SolutionKind::Solved;
}
return SolutionKind::Unsolved;
}
// If the first base type is a bridgeable object type, this can only be an
// upcast.
bool isUpcast = baseType1->isBridgeableObjectType();
if (isUpcast) {
increaseScore(SK_CollectionUpcastConversion);
} else {
// This might be a bridged upcast.
Type bridgedBaseType1 = TC.getBridgedToObjC(DC, baseType1);
if (!bridgedBaseType1) {
// FIXME: Record failure.
return SolutionKind::Error;
}
// Look through the destination base type. We need its structure to
// determine whether we'll be bridging or upcasting the base type.
TypeVariableType *baseTypeVar2 = nullptr;
baseType2 = getFixedTypeRecursive(baseType2, baseTypeVar2, false, false);
// If the destination base type is a type variable, we can't simplify
// this now.
if (baseTypeVar2) {
if (flags & TMF_GenerateConstraints) {
addConstraint(
Constraint::createRestricted(*this, getConstraintKind(matchKind),
restriction, type1, type2,
getConstraintLocator(locator)));
return SolutionKind::Solved;
}
return SolutionKind::Unsolved;
}
// This can be a bridging upcast.
if (baseType2->isBridgeableObjectType())
baseType1 = bridgedBaseType1;
increaseScore(SK_CollectionBridgedConversion);
}
addContextualScore();
assert(matchKind >= TypeMatchKind::Conversion);
// The source base type must be a subtype of the destination base type.
return matchTypes(baseType1, baseType2, TypeMatchKind::Subtype, subFlags,
locator);
}
// T bridges to C and C < U ===> T <c U
case ConversionRestrictionKind::BridgeToObjC: {
auto objcClass = TC.getBridgedToObjC(DC, type1);
assert(objcClass && "type is not bridged to Objective-C?");
addContextualScore();
increaseScore(SK_UserConversion); // FIXME: Use separate score kind?
if (worseThanBestSolution()) {
return SolutionKind::Error;
}
// If the bridged value type is generic, the generic arguments
// must be bridged to Objective-C for bridging to succeed.
if (auto bgt1 = type1->getAs<BoundGenericType>()) {
unsigned argIdx = 0;
for (auto arg: bgt1->getGenericArgs()) {
addConstraint(
Constraint::create(*this,
ConstraintKind::BridgedToObjectiveC,
arg, Type(), DeclName(),
getConstraintLocator(
locator.withPathElement(
LocatorPathElt::getGenericArgument(
argIdx++)))));
}
}
return matchTypes(objcClass, type2, TypeMatchKind::Subtype, subFlags,
locator);
}
// U bridges to C and T < C ===> T <c U
case ConversionRestrictionKind::BridgeFromObjC: {
auto objcClass = TC.getBridgedToObjC(DC, type2);
assert(objcClass && "type is not bridged to Objective-C?");
addContextualScore();
increaseScore(SK_UserConversion); // FIXME: Use separate score kind?
if (worseThanBestSolution()) {
return SolutionKind::Error;
}
// If the bridged value type is generic, the generic arguments
// must match the
// FIXME: This should be an associated type of the protocol.
if (auto bgt1 = type2->getAs<BoundGenericType>()) {
if (bgt1->getDecl() == TC.Context.getArrayDecl()) {
// [AnyObject]
addConstraint(ConstraintKind::Bind, bgt1->getGenericArgs()[0],
TC.Context.getProtocol(KnownProtocolKind::AnyObject)
->getDeclaredType(),
getConstraintLocator(
locator.withPathElement(
LocatorPathElt::getGenericArgument(0))));
} else if (bgt1->getDecl() == TC.Context.getDictionaryDecl()) {
// [NSObject : AnyObject]
auto NSObjectType = TC.getNSObjectType(DC);
if (!NSObjectType) {
// Not a bridging case. Should we detect this earlier?
return SolutionKind::Error;
}
addConstraint(ConstraintKind::Bind, bgt1->getGenericArgs()[0],
NSObjectType,
getConstraintLocator(
locator.withPathElement(
LocatorPathElt::getGenericArgument(0))));
addConstraint(ConstraintKind::Bind, bgt1->getGenericArgs()[1],
TC.Context.getProtocol(KnownProtocolKind::AnyObject)
->getDeclaredType(),
getConstraintLocator(
locator.withPathElement(
LocatorPathElt::getGenericArgument(1))));
} else if (bgt1->getDecl() == TC.Context.getSetDecl()) {
auto NSObjectType = TC.getNSObjectType(DC);
if (!NSObjectType) {
// Not a bridging case. Should we detect this earlier?
return SolutionKind::Error;
}
addConstraint(ConstraintKind::Bind, bgt1->getGenericArgs()[0],
NSObjectType,
getConstraintLocator(
locator.withPathElement(
LocatorPathElt::getGenericArgument(0))));
} else {
llvm_unreachable("unhandled generic bridged type");
}
}
return matchTypes(type1, objcClass, TypeMatchKind::Subtype, subFlags,
locator);
}
case ConversionRestrictionKind::BridgeToNSError: {
increaseScore(SK_UserConversion); // FIXME: Use separate score kind?
// The input type must be an ErrorType subtype.
auto errorType = TC.Context.getProtocol(KnownProtocolKind::ErrorType)
->getDeclaredType();
return matchTypes(type1, errorType, TypeMatchKind::Subtype, subFlags,
locator);
}
// T' < U and T a toll-free-bridged to T' ===> T' <c U
case ConversionRestrictionKind::CFTollFreeBridgeToObjC: {
increaseScore(SK_UserConversion); // FIXME: Use separate score kind?
if (worseThanBestSolution()) {
return SolutionKind::Error;
}
auto nativeClass = type1->getClassOrBoundGenericClass();
auto bridgedObjCClass
= nativeClass->getAttrs().getAttribute<ObjCBridgedAttr>()->getObjCClass();
return matchTypes(bridgedObjCClass->getDeclaredInterfaceType(),
type2, TypeMatchKind::Subtype, subFlags, locator);
}
// T < U' and U a toll-free-bridged to U' ===> T <c U
case ConversionRestrictionKind::ObjCTollFreeBridgeToCF: {
increaseScore(SK_UserConversion); // FIXME: Use separate score kind?
if (worseThanBestSolution()) {
return SolutionKind::Error;
}
auto nativeClass = type2->getClassOrBoundGenericClass();
auto bridgedObjCClass
= nativeClass->getAttrs().getAttribute<ObjCBridgedAttr>()->getObjCClass();
return matchTypes(type1,
bridgedObjCClass->getDeclaredInterfaceType(),
TypeMatchKind::Subtype, subFlags, locator);
}
}
llvm_unreachable("bad conversion restriction");
}
bool ConstraintSystem::recordFix(Fix fix, ConstraintLocatorBuilder locator) {
auto &ctx = getASTContext();
if (ctx.LangOpts.DebugConstraintSolver) {
auto &log = ctx.TypeCheckerDebug->getStream();
log.indent(solverState? solverState->depth * 2 + 2 : 0)
<< "(attempting fix ";
fix.print(log, this);
log << " @";
getConstraintLocator(locator)->dump(&ctx.SourceMgr, log);
log << ")\n";
}
// Record the fix.
if (fix.getKind() != FixKind::None) {
// Increase the score. If this would make the current solution worse than
// the best solution we've seen already, stop now.
increaseScore(SK_Fix);
if (worseThanBestSolution())
return true;
Fixes.push_back({fix, getConstraintLocator(locator)});
}
return false;
}
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyFixConstraint(Fix fix,
Type type1, Type type2,
TypeMatchKind matchKind,
unsigned flags,
ConstraintLocatorBuilder locator) {
if (recordFix(fix, locator)) {
return SolutionKind::Error;
}
// Try with the fix.
unsigned subFlags = flags | TMF_ApplyingFix | TMF_GenerateConstraints;
switch (fix.getKind()) {
case FixKind::None:
return matchTypes(type1, type2, matchKind, subFlags, locator);
case FixKind::RemoveNullaryCall:
llvm_unreachable("Always applied directly");
case FixKind::ForceOptional:
// Assume that '!' was applied to the first type.
return matchTypes(type1->getRValueObjectType()->getOptionalObjectType(),
type2, matchKind, subFlags, locator);
case FixKind::ForceDowncast:
// These work whenever they are suggested.
return SolutionKind::Solved;
case FixKind::AddressOf:
// Assume that '&' was applied to the first type, turning an lvalue into
// an inout.
return matchTypes(InOutType::get(type1->getRValueType()), type2,
matchKind, subFlags, locator);
case FixKind::TupleToScalar:
return matchTypes(type1->castTo<TupleType>()->getElementType(0),
type2, matchKind, subFlags,
locator.withPathElement(
LocatorPathElt::getTupleElement(0)));
case FixKind::ScalarToTuple: {
auto tuple2 = type2->castTo<TupleType>();
int scalarFieldIdx = tuple2->getElementForScalarInit();
assert(scalarFieldIdx >= 0 && "Invalid tuple for scalar-to-tuple");
const auto &elt = tuple2->getElement(scalarFieldIdx);
auto scalarFieldTy = elt.isVararg()? elt.getVarargBaseTy() : elt.getType();
return matchTypes(type1, scalarFieldTy, matchKind, subFlags,
locator.withPathElement(
ConstraintLocator::ScalarToTuple));
}
case FixKind::RelabelCallTuple:
case FixKind::OptionalToBoolean:
// The actual semantics are handled elsewhere.
return SolutionKind::Solved;
case FixKind::FromRawToInit:
case FixKind::ToRawToRawValue:
case FixKind::CoerceToCheckedCast:
case FixKind::AllZerosToInit:
llvm_unreachable("handled elsewhere");
}
}
ConstraintSystem::SolutionKind
ConstraintSystem::simplifyConstraint(const Constraint &constraint) {
switch (constraint.getKind()) {
case ConstraintKind::Bind:
case ConstraintKind::Equal:
case ConstraintKind::BindParam:
case ConstraintKind::Subtype:
case ConstraintKind::Conversion:
case ConstraintKind::ExplicitConversion:
case ConstraintKind::ArgumentConversion:
case ConstraintKind::ArgumentTupleConversion:
case ConstraintKind::OperatorArgumentTupleConversion:
case ConstraintKind::OperatorArgumentConversion: {
// For relational constraints, match up the types.
auto matchKind = getTypeMatchKind(constraint.getKind());
// If there is a fix associated with this constraint, apply it before
// we continue.
if (auto fix = constraint.getFix()) {
return simplifyFixConstraint(*fix, constraint.getFirstType(),
constraint.getSecondType(), matchKind,
TMF_GenerateConstraints,
constraint.getLocator());
}
// If there is a restriction on this constraint, apply it directly rather
// than going through the general \c matchTypes() machinery.
if (auto restriction = constraint.getRestriction()) {
SolutionKind result = simplifyRestrictedConstraint(*restriction,
constraint.getFirstType(),
constraint.getSecondType(),
matchKind,
0,
constraint.getLocator());
// If we actually solved something, record what we did.
switch(result) {
case SolutionKind::Error:
case SolutionKind::Unsolved:
break;
case SolutionKind::Solved:
ConstraintRestrictions.push_back(
std::make_tuple(constraint.getFirstType(),
constraint.getSecondType(), *restriction));
break;
}
return result;
}
return matchTypes(constraint.getFirstType(), constraint.getSecondType(),
matchKind,
TMF_None, constraint.getLocator());
}
case ConstraintKind::ApplicableFunction:
return simplifyApplicableFnConstraint(constraint);
case ConstraintKind::DynamicTypeOf:
return simplifyDynamicTypeOfConstraint(constraint);
case ConstraintKind::BindOverload:
resolveOverload(constraint.getLocator(), constraint.getFirstType(),
constraint.getOverloadChoice());
return SolutionKind::Solved;
case ConstraintKind::ConformsTo:
case ConstraintKind::SelfObjectOfProtocol:
return simplifyConformsToConstraint(
constraint.getFirstType(),
constraint.getSecondType(),
constraint.getKind(),
constraint.getLocator(),
TMF_None);
case ConstraintKind::CheckedCast: {
auto result = simplifyCheckedCastConstraint(constraint.getFirstType(),
constraint.getSecondType(),
constraint.getLocator());
// NOTE: simplifyCheckedCastConstraint() may return Unsolved, e.g. if the
// subexpression's type is unresolved. Don't record the fix until we
// successfully simplify the constraint.
if (result == SolutionKind::Solved) {
if (auto fix = constraint.getFix()) {
if (recordFix(*fix, constraint.getLocator())) {
return SolutionKind::Error;
}
}
}
return result;
}
case ConstraintKind::OptionalObject:
return simplifyOptionalObjectConstraint(constraint);
case ConstraintKind::ValueMember:
case ConstraintKind::UnresolvedValueMember:
case ConstraintKind::TypeMember:
return simplifyMemberConstraint(constraint);
case ConstraintKind::Archetype:
return simplifyArchetypeConstraint(constraint);
case ConstraintKind::BridgedToObjectiveC:
return simplifyBridgedToObjectiveCConstraint(constraint);
case ConstraintKind::Class:
return simplifyClassConstraint(constraint);
case ConstraintKind::Defaultable:
return simplifyDefaultableConstraint(constraint);
case ConstraintKind::Disjunction:
// Disjunction constraints are never solved here.
return SolutionKind::Unsolved;
}
}