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[Type checker] Eliminate the 'literalConformanceProto' state on type variables.

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The 'literalConformanceProto' field of
TypeVariableType::Implementation didn't take into account equivalence
classes of type variables. Eliminate it, and either look at the actual
expressions (for optimizing constraints during constraint generation)
or the actual constraints on a given type variable (for determining
whether to include optionals in the set of potential type variable
bindings).

(cherry picked from commit 6bdd9cfae5)
This commit is contained in:
Doug Gregor
2016-10-11 16:57:53 -07:00
parent 053f3b4b48
commit 49b833b51a
7 changed files with 101 additions and 74 deletions
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3
lib/Sema/CSDiag.cpp
View File

@@ -2920,7 +2920,8 @@ bool FailureDiagnosis::diagnoseGeneralConversionFailure(Constraint *constraint){
// If simplification has turned this into the same types, then this isn't the
// broken constraint that we're looking for.
if (fromType->isEqual(toType) &&
constraint->getKind() != ConstraintKind::ConformsTo)
constraint->getKind() != ConstraintKind::ConformsTo &&
constraint->getKind() != ConstraintKind::LiteralConformsTo)
return false;

98
lib/Sema/CSGen.cpp
View File

@@ -500,49 +500,47 @@ namespace {
return false;
}
/// Determine whether the given parameter and argument type should be
/// Determine whether the given parameter type and argument should be
/// "favored" because they match exactly.
bool isFavoredParamAndArg(ConstraintSystem &CS,
Type paramTy,
Expr *arg,
Type argTy,
Type otherArgTy) {
if (argTy->getAs<LValueType>())
Expr *otherArg = nullptr,
Type otherArgTy = Type()) {
// Determine the argument type.
argTy = argTy->getLValueOrInOutObjectType();
if (!otherArgTy.isNull() &&
otherArgTy->getAs<LValueType>())
otherArgTy = otherArgTy->getLValueOrInOutObjectType();
// Do the types match exactly?
if (paramTy->isEqual(argTy))
return true;
// If the argument is a type variable created for a literal that has a
// default type, this is a favored param/arg pair if the parameter is of
// that default type.
// Is the argument a type variable...
if (auto argTypeVar = argTy->getAs<TypeVariableType>()) {
if (auto proto = argTypeVar->getImpl().literalConformanceProto) {
// If it's a struct type associated with the literal conformance,
// test against it directly. This helps to avoid 'widening' the
// favored type to the default type for the literal.
if (!otherArgTy.isNull() &&
otherArgTy->getAs<StructType>()) {
// If the argument is a literal, this is a favored param/arg pair if
// the parameter is of that default type.
auto &tc = CS.getTypeChecker();
auto literalProto = tc.getLiteralProtocol(arg->getSemanticsProvidingExpr());
if (!literalProto) return false;
if (CS.TC.conformsToProtocol(otherArgTy,
proto,
CS.DC,
ConformanceCheckFlags::InExpression)) {
return otherArgTy->isEqual(paramTy);
}
} else if (auto defaultTy = CS.TC.getDefaultType(proto, CS.DC)) {
if (paramTy->isEqual(defaultTy)) {
return true;
}
}
}
// Dig out the second argument type.
if (otherArgTy)
otherArgTy = otherArgTy->getLValueOrInOutObjectType();
// If there is another, concrete argument, check whether it's type
// conforms to the literal protocol and test against it directly.
// This helps to avoid 'widening' the favored type to the default type for
// the literal.
if (otherArgTy && otherArgTy->getAnyNominal()) {
return otherArgTy->isEqual(paramTy) &&
tc.conformsToProtocol(otherArgTy, literalProto, CS.DC,
ConformanceCheckFlags::InExpression);
}
// If there is a default type for the literal protocol, check whether
// it is the same as the parameter type.
// Check whether there is a default type to compare against.
if (Type defaultType = tc.getDefaultType(literalProto, CS.DC))
return paramTy->isEqual(defaultType);
return false;
}
@@ -742,9 +740,6 @@ namespace {
/// for the operand and contextual type.
void favorMatchingUnaryOperators(ApplyExpr *expr,
ConstraintSystem &CS) {
// Find the argument type.
auto argTy = expr->getArg()->getType()->getWithoutParens();
// Determine whether the given declaration is favored.
auto isFavoredDecl = [&](ValueDecl *value) -> bool {
auto valueTy = value->getType();
@@ -762,7 +757,8 @@ namespace {
auto resultTy = fnTy->getResult();
auto contextualTy = CS.getContextualType(expr);
return isFavoredParamAndArg(CS, paramTy, argTy, Type()) &&
return isFavoredParamAndArg(CS, paramTy, expr->getArg(),
expr->getArg()->getType()->getWithoutParens()) &&
(!contextualTy || contextualTy->isEqual(resultTy));
};
@@ -881,8 +877,10 @@ namespace {
if (!fnTy)
return false;
auto firstFavoredTy = CS.getFavoredType(argTupleExpr->getElement(0));
auto secondFavoredTy = CS.getFavoredType(argTupleExpr->getElement(1));
Expr *firstArg = argTupleExpr->getElement(0);
auto firstFavoredTy = CS.getFavoredType(firstArg);
Expr *secondArg = argTupleExpr->getElement(1);
auto secondFavoredTy = CS.getFavoredType(secondArg);
auto favoredExprTy = CS.getFavoredType(expr);
@@ -926,8 +924,10 @@ namespace {
auto contextualTy = CS.getContextualType(expr);
return
(isFavoredParamAndArg(CS, firstParamTy, firstArgTy, secondArgTy) ||
isFavoredParamAndArg(CS, secondParamTy, secondArgTy, firstArgTy)) &&
(isFavoredParamAndArg(CS, firstParamTy, firstArg, firstArgTy,
secondArg, secondArgTy) ||
isFavoredParamAndArg(CS, secondParamTy, secondArg, secondArgTy,
firstArg, firstArgTy)) &&
firstParamTy->isEqual(secondParamTy) &&
(!contextualTy || contextualTy->isEqual(resultTy));
};
@@ -1083,7 +1083,7 @@ namespace {
auto keyTy = dictTy->first;
auto valueTy = dictTy->second;
if (isFavoredParamAndArg(CS, keyTy, index->getType(), Type())) {
if (isFavoredParamAndArg(CS, keyTy, index, index->getType())) {
outputTy = OptionalType::get(valueTy);
if (isLValueBase)
@@ -1164,10 +1164,7 @@ namespace {
auto tv = CS.createTypeVariable(CS.getConstraintLocator(expr),
TVO_PrefersSubtypeBinding);
tv->getImpl().literalConformanceProto = protocol;
CS.addConstraint(ConstraintKind::ConformsTo, tv,
CS.addConstraint(ConstraintKind::LiteralConformsTo, tv,
protocol->getDeclaredType(),
CS.getConstraintLocator(expr));
return tv;
@@ -1190,8 +1187,7 @@ namespace {
// ExpressibleByStringInterpolation protocol.
auto locator = CS.getConstraintLocator(expr);
auto tv = CS.createTypeVariable(locator, TVO_PrefersSubtypeBinding);
tv->getImpl().literalConformanceProto = interpolationProto;
CS.addConstraint(ConstraintKind::ConformsTo, tv,
CS.addConstraint(ConstraintKind::LiteralConformsTo, tv,
interpolationProto->getDeclaredType(),
locator);
@@ -1264,9 +1260,7 @@ namespace {
auto tv = CS.createTypeVariable(CS.getConstraintLocator(expr),
TVO_PrefersSubtypeBinding);
tv->getImpl().literalConformanceProto = protocol;
CS.addConstraint(ConstraintKind::ConformsTo, tv,
CS.addConstraint(ConstraintKind::LiteralConformsTo, tv,
protocol->getDeclaredType(),
CS.getConstraintLocator(expr));
@@ -1683,7 +1677,7 @@ namespace {
contextualArrayElementType =
CS.getBaseTypeForArrayType(contextualType.getPointer());
CS.addConstraint(ConstraintKind::ConformsTo, contextualType,
CS.addConstraint(ConstraintKind::LiteralConformsTo, contextualType,
arrayProto->getDeclaredType(),
locator);
@@ -1703,7 +1697,7 @@ namespace {
auto arrayTy = CS.createTypeVariable(locator, TVO_PrefersSubtypeBinding);
// The array must be an array literal type.
CS.addConstraint(ConstraintKind::ConformsTo, arrayTy,
CS.addConstraint(ConstraintKind::LiteralConformsTo, arrayTy,
arrayProto->getDeclaredType(),
locator);
@@ -1769,8 +1763,8 @@ namespace {
auto dictionaryTy = CS.createTypeVariable(locator,
TVO_PrefersSubtypeBinding);
// The array must be a dictionary literal type.
CS.addConstraint(ConstraintKind::ConformsTo, dictionaryTy,
// The dictionary must be a dictionary literal type.
CS.addConstraint(ConstraintKind::LiteralConformsTo, dictionaryTy,
dictionaryProto->getDeclaredType(),
locator);

3
lib/Sema/CSSimplify.cpp
View File

@@ -2288,6 +2288,7 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
return SolutionKind::Solved;
break;
case ConstraintKind::ConformsTo:
case ConstraintKind::LiteralConformsTo:
// Check whether this type conforms to the protocol.
if (TC.conformsToProtocol(type, protocol, DC,
ConformanceCheckFlags::InExpression))
@@ -3467,6 +3468,7 @@ static TypeMatchKind getTypeMatchKind(ConstraintKind kind) {
llvm_unreachable("Overload binding constraints don't involve type matches");
case ConstraintKind::ConformsTo:
case ConstraintKind::LiteralConformsTo:
case ConstraintKind::SelfObjectOfProtocol:
llvm_unreachable("Conformance constraints don't involve type matches");
@@ -4126,6 +4128,7 @@ ConstraintSystem::simplifyConstraint(const Constraint &constraint) {
return SolutionKind::Solved;
case ConstraintKind::ConformsTo:
case ConstraintKind::LiteralConformsTo:
case ConstraintKind::SelfObjectOfProtocol:
return simplifyConformsToConstraint(
constraint.getFirstType(),

42
lib/Sema/CSSolver.cpp
View File

@@ -62,14 +62,24 @@ static Optional<Type> checkTypeOfBinding(ConstraintSystem &cs,
return None;
// If the type is a type variable itself, don't permit the binding.
// FIXME: This is a hack. We need to be smarter about whether there's enough
// structure in the type to produce an interesting binding, or not.
if (auto bindingTypeVar = type->getRValueType()->getAs<TypeVariableType>()) {
if (isNilLiteral &&
bindingTypeVar->getImpl().literalConformanceProto &&
bindingTypeVar->getImpl().literalConformanceProto->isSpecificProtocol(
KnownProtocolKind::ExpressibleByNilLiteral))
if (isNilLiteral) {
*isNilLiteral = false;
// Look for a literal-conformance constraint on the type variable.
SmallVector<Constraint *, 8> constraints;
cs.getConstraintGraph().gatherConstraints(bindingTypeVar, constraints);
for (auto constraint : constraints) {
if (constraint->getKind() == ConstraintKind::LiteralConformsTo &&
constraint->getProtocol()->isSpecificProtocol(
KnownProtocolKind::ExpressibleByNilLiteral) &&
cs.simplifyType(constraint->getFirstType())
->isEqual(bindingTypeVar)) {
*isNilLiteral = true;
break;
}
}
}
return None;
}
@@ -667,6 +677,7 @@ static bool shouldBindToValueType(Constraint *constraint)
case ConstraintKind::Equal:
case ConstraintKind::BindParam:
case ConstraintKind::ConformsTo:
case ConstraintKind::LiteralConformsTo:
case ConstraintKind::CheckedCast:
case ConstraintKind::SelfObjectOfProtocol:
case ConstraintKind::ApplicableFunction:
@@ -782,8 +793,19 @@ static PotentialBindings getPotentialBindings(ConstraintSystem &cs,
result.InvolvesTypeVariables = true;
continue;
case ConstraintKind::LiteralConformsTo:
// If there is a 'nil' literal constraint, we might need optional
// supertype bindings.
if (constraint->getProtocol()->isSpecificProtocol(
KnownProtocolKind::ExpressibleByNilLiteral))
addOptionalSupertypeBindings = true;
SWIFT_FALLTHROUGH;
case ConstraintKind::ConformsTo:
case ConstraintKind::SelfObjectOfProtocol: {
// FIXME: Only for LiteralConformsTo?
// If there is a default literal type for this protocol, it's a
// potential binding.
auto defaultType = tc.getDefaultType(constraint->getProtocol(), cs.DC);
@@ -908,13 +930,17 @@ static PotentialBindings getPotentialBindings(ConstraintSystem &cs,
// Check whether we can perform this binding.
// FIXME: this has a super-inefficient extraneous simplifyType() in it.
bool isNilLiteral = false;
if (auto boundType = checkTypeOfBinding(cs, typeVar, type, &isNilLiteral)) {
bool *isNilLiteralPtr = nullptr;
if (!addOptionalSupertypeBindings && kind == AllowedBindingKind::Supertypes)
isNilLiteralPtr = &isNilLiteral;
if (auto boundType = checkTypeOfBinding(cs, typeVar, type,
isNilLiteralPtr)) {
type = *boundType;
if (type->hasTypeVariable())
result.InvolvesTypeVariables = true;
} else {
// If the bound is a 'nil' literal type, add optional supertype bindings.
if (isNilLiteral && kind == AllowedBindingKind::Supertypes) {
if (isNilLiteral) {
addOptionalSupertypeBindings = true;
continue;
}

5
lib/Sema/Constraint.cpp
View File

@@ -61,6 +61,7 @@ Constraint::Constraint(ConstraintKind Kind, Type First, Type Second,
case ConstraintKind::OperatorArgumentTupleConversion:
case ConstraintKind::OperatorArgumentConversion:
case ConstraintKind::ConformsTo:
case ConstraintKind::LiteralConformsTo:
case ConstraintKind::CheckedCast:
case ConstraintKind::SelfObjectOfProtocol:
case ConstraintKind::DynamicTypeOf:
@@ -144,6 +145,7 @@ Constraint::Constraint(ConstraintKind kind, Fix fix,
ProtocolDecl *Constraint::getProtocol() const {
assert((Kind == ConstraintKind::ConformsTo ||
Kind == ConstraintKind::LiteralConformsTo ||
Kind == ConstraintKind::SelfObjectOfProtocol)
&& "Not a conformance constraint");
return Types.Second->castTo<ProtocolType>()->getDecl();
@@ -162,6 +164,7 @@ Constraint *Constraint::clone(ConstraintSystem &cs) const {
case ConstraintKind::OperatorArgumentTupleConversion:
case ConstraintKind::OperatorArgumentConversion:
case ConstraintKind::ConformsTo:
case ConstraintKind::LiteralConformsTo:
case ConstraintKind::CheckedCast:
case ConstraintKind::DynamicTypeOf:
case ConstraintKind::SelfObjectOfProtocol:
@@ -238,6 +241,7 @@ void Constraint::print(llvm::raw_ostream &Out, SourceManager *sm) const {
case ConstraintKind::OperatorArgumentConversion:
Out << " operator arg conv "; break;
case ConstraintKind::ConformsTo: Out << " conforms to "; break;
case ConstraintKind::LiteralConformsTo: Out << " literal conforms to "; break;
case ConstraintKind::CheckedCast: Out << " checked cast to "; break;
case ConstraintKind::SelfObjectOfProtocol: Out << " Self type of "; break;
case ConstraintKind::ApplicableFunction: Out << " applicable fn "; break;
@@ -486,6 +490,7 @@ gatherReferencedTypeVars(Constraint *constraint,
case ConstraintKind::BindOverload:
case ConstraintKind::Class:
case ConstraintKind::ConformsTo:
case ConstraintKind::LiteralConformsTo:
case ConstraintKind::SelfObjectOfProtocol:
constraint->getFirstType()->getTypeVariables(typeVars);

4
lib/Sema/Constraint.h
View File

@@ -81,6 +81,9 @@ enum class ConstraintKind : char {
/// \brief The first type must conform to the second type (which is a
/// protocol type).
ConformsTo,
/// \brief The first type describes a literal that conforms to the second
/// type, which is one of the known expressible-by-literal protocols.
LiteralConformsTo,
/// A checked cast from the first type to the second.
CheckedCast,
/// \brief The first type can act as the Self type of the second type (which
@@ -473,6 +476,7 @@ public:
case ConstraintKind::OperatorArgumentTupleConversion:
case ConstraintKind::OperatorArgumentConversion:
case ConstraintKind::ConformsTo:
case ConstraintKind::LiteralConformsTo:
case ConstraintKind::CheckedCast:
case ConstraintKind::SelfObjectOfProtocol:
case ConstraintKind::ApplicableFunction:

6
lib/Sema/ConstraintSystem.h
View File

@@ -158,12 +158,6 @@ class TypeVariableType::Implementation {
friend class constraints::SavedTypeVariableBinding;
public:
/// \brief If this type variable is an opened literal expression, keep track
/// of the associated literal conformance for optimization and diagnostic
/// purposes.
ProtocolDecl *literalConformanceProto = nullptr;
explicit Implementation(constraints::ConstraintLocator *locator,
unsigned options)
: Options(options), locator(locator),