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TypeCheckGeneric.cpp
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//===--- TypeCheckGeneric.cpp - Generics ----------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// This file implements support for generics.
//
//===----------------------------------------------------------------------===//
#include "TypeCheckProtocol.h"
#include "TypeCheckType.h"
#include "TypeChecker.h"
#include "swift/AST/ASTWalker.h"
#include "swift/AST/DiagnosticsSema.h"
#include "swift/AST/ExistentialLayout.h"
#include "swift/AST/GenericEnvironment.h"
#include "swift/AST/ParameterList.h"
#include "swift/AST/ProtocolConformance.h"
#include "swift/AST/TypeCheckRequests.h"
#include "swift/AST/TypeResolutionStage.h"
#include "swift/AST/Types.h"
#include "swift/Basic/Defer.h"
#include "llvm/Support/ErrorHandling.h"
using namespace swift;
//
// Generic functions
//
/// Get the opaque type representing the return type of a declaration, or
/// create it if it does not yet exist.
OpaqueTypeDecl *
OpaqueResultTypeRequest::evaluate(Evaluator &evaluator,
ValueDecl *originatingDecl) const {
auto *repr = originatingDecl->getOpaqueResultTypeRepr();
assert(repr && "Declaration does not have an opaque result type");
auto *dc = originatingDecl->getInnermostDeclContext();
auto &ctx = dc->getASTContext();
// Protocol requirements can't have opaque return types.
//
// TODO: Maybe one day we could treat this as sugar for an associated type.
if (isa<ProtocolDecl>(originatingDecl->getDeclContext())
&& originatingDecl->isProtocolRequirement()) {
SourceLoc fixitLoc;
if (auto vd = dyn_cast<VarDecl>(originatingDecl)) {
fixitLoc = vd->getParentPatternBinding()->getStartLoc();
} else {
fixitLoc = originatingDecl->getStartLoc();
}
std::string result;
const char *const placeholder = "<#AssocType#>";
{
llvm::raw_string_ostream out(result);
out << "associatedtype " << placeholder << ": ";
// FIXME [OPAQUE SUPPORT]: to produce the right associate type for the
// replacement in general, we would need to recurse into the type repr and
// replace every `OpaqueReturnType` with its 'constraint'. Things get
// trickier when we allow named opaque return types.
if (isa<OpaqueReturnTypeRepr>(repr)) {
cast<OpaqueReturnTypeRepr>(repr)->getConstraint()->print(out);
} else {
out << "<#type#>";
}
out << "\n";
}
ctx.Diags
.diagnose(repr->getLoc(), diag::opaque_type_in_protocol_requirement)
.fixItInsert(fixitLoc, result)
.fixItReplace(repr->getSourceRange(), placeholder);
return nullptr;
}
// Check the availability of the opaque type runtime support.
if (!ctx.LangOpts.DisableAvailabilityChecking) {
auto runningOS =
TypeChecker::overApproximateAvailabilityAtLocation(
repr->getLoc(),
originatingDecl->getInnermostDeclContext());
auto availability = ctx.getOpaqueTypeAvailability();
if (!runningOS.isContainedIn(availability)) {
TypeChecker::diagnosePotentialOpaqueTypeUnavailability(
repr->getSourceRange(),
originatingDecl->getInnermostDeclContext(),
UnavailabilityReason::requiresVersionRange(availability.getOSVersion()));
}
}
// Create a generic signature for the opaque environment. This is the outer
// generic signature with an added generic parameters representing the opaque
// types and their interface constraints.
auto originatingDC = originatingDecl->getInnermostDeclContext();
auto outerGenericSignature = originatingDC->getGenericSignatureOfContext();
unsigned opaqueSignatureDepth =
outerGenericSignature
? outerGenericSignature.getGenericParams().back()->getDepth() + 1
: 0;
// Determine the context of the opaque type declaration we'll be creating.
auto parentDC = originatingDecl->getDeclContext();
auto originatingGenericContext = originatingDecl->getAsGenericContext();
GenericParamList *genericParams;
GenericSignature interfaceSignature;
CollectedOpaqueReprs opaqueReprs;
if (auto namedOpaque = dyn_cast<NamedOpaqueReturnTypeRepr>(repr)) {
// Produce the generic signature for the opaque type.
genericParams = namedOpaque->getGenericParams();
genericParams->setDepth(opaqueSignatureDepth);
InferredGenericSignatureRequest request{
originatingDC->getParentModule(),
outerGenericSignature.getPointer(),
genericParams,
WhereClauseOwner(originatingDC, genericParams),
/*addedRequirements=*/{},
/*inferenceSources=*/{},
/*allowConcreteGenericParams=*/false};
interfaceSignature = evaluateOrDefault(
ctx.evaluator, request, GenericSignatureWithError())
.getPointer();
if (!interfaceSignature) {
// Already produced an error.
return nullptr;
}
} else {
opaqueReprs = repr->collectOpaqueReturnTypeReprs();
SmallVector<GenericTypeParamType *, 2> genericParamTypes;
SmallVector<Requirement, 2> requirements;
for (unsigned i = 0; i < opaqueReprs.size(); ++i) {
auto *currentRepr = opaqueReprs[i];
// Usually, we resolve the opaque constraint and bail if it isn't a class
// or existential type (see below). However, in this case we know we will
// fail, so we can bail early and provide a better diagnostic.
if (auto *optionalRepr =
dyn_cast<OptionalTypeRepr>(currentRepr->getConstraint())) {
std::string buf;
llvm::raw_string_ostream stream(buf);
stream << "(some " << optionalRepr->getBase() << ")?";
ctx.Diags.diagnose(currentRepr->getLoc(),
diag::opaque_type_invalid_constraint);
ctx.Diags
.diagnose(currentRepr->getLoc(), diag::opaque_of_optional_rewrite)
.fixItReplaceChars(currentRepr->getStartLoc(),
currentRepr->getEndLoc(), stream.str());
return nullptr;
}
auto *paramType = GenericTypeParamType::get(/*type sequence*/ false,
opaqueSignatureDepth, i, ctx);
genericParamTypes.push_back(paramType);
// Try to resolve the constraint repr in the parent decl context. It
// should be some kind of existential type. Pass along the error type if
// resolving the repr failed.
auto constraintType = TypeResolution::forInterface(
dc, TypeResolverContext::GenericRequirement,
// Unbound generics and placeholders are
// meaningless in opaque types.
/*unboundTyOpener*/ nullptr,
/*placeholderHandler*/ nullptr)
.resolveType(currentRepr->getConstraint());
if (constraintType->hasError())
return nullptr;
RequirementKind kind;
if (constraintType->isConstraintType())
kind = RequirementKind::Conformance;
else if (constraintType->getClassOrBoundGenericClass())
kind = RequirementKind::Superclass;
else {
// Error out if the constraint type isn't a class or existential type.
ctx.Diags.diagnose(currentRepr->getLoc(),
diag::opaque_type_invalid_constraint);
return nullptr;
}
assert(!constraintType->hasArchetype());
requirements.emplace_back(kind, paramType, constraintType);
}
interfaceSignature = buildGenericSignature(ctx, outerGenericSignature,
genericParamTypes,
std::move(requirements));
genericParams = originatingGenericContext
? originatingGenericContext->getGenericParams()
: nullptr;
}
// Create the OpaqueTypeDecl for the result type.
auto opaqueDecl = OpaqueTypeDecl::get(
originatingDecl, genericParams, parentDC, interfaceSignature,
opaqueReprs);
opaqueDecl->copyFormalAccessFrom(originatingDecl);
if (auto originatingSig = originatingDC->getGenericSignatureOfContext()) {
opaqueDecl->setGenericSignature(originatingSig);
}
// Resolving in the context of `opaqueDecl` allows type resolution to create
// opaque archetypes where needed
auto interfaceType =
TypeResolution::forInterface(opaqueDecl, TypeResolverContext::None,
/*unboundTyOpener*/ nullptr,
/*placeholderHandler*/ nullptr)
.resolveType(repr);
// Opaque types cannot be used in parameter position.
Type desugared = interfaceType->getDesugaredType();
bool hasError = desugared.findIf([&](Type type) -> bool {
if (auto *fnType = type->getAs<FunctionType>()) {
for (auto param : fnType->getParams()) {
if (!param.getPlainType()->hasOpaqueArchetype())
continue;
ctx.Diags.diagnose(repr->getLoc(),
diag::opaque_type_in_parameter,
false, interfaceType);
return true;
}
}
return false;
});
if (hasError)
return nullptr;
auto metatype = MetatypeType::get(interfaceType);
opaqueDecl->setInterfaceType(metatype);
return opaqueDecl;
}
/// Determine whether the given type is \c Self, an associated type of \c Self,
/// or a concrete type.
static bool isSelfDerivedOrConcrete(Type protoSelf, Type type) {
// Check for a concrete type.
if (!type->hasTypeParameter())
return true;
if (type->isTypeParameter() &&
type->getRootGenericParam()->isEqual(protoSelf))
return true;
return false;
}
// For a generic requirement in a protocol, make sure that the requirement
// set didn't add any requirements to Self or its associated types.
void TypeChecker::checkProtocolSelfRequirements(ValueDecl *decl) {
// For a generic requirement in a protocol, make sure that the requirement
// set didn't add any requirements to Self or its associated types.
if (auto *proto = dyn_cast<ProtocolDecl>(decl->getDeclContext())) {
auto &ctx = proto->getASTContext();
auto protoSelf = proto->getSelfInterfaceType();
auto sig = decl->getInnermostDeclContext()->getGenericSignatureOfContext();
for (auto req : sig.getRequirements()) {
// If one of the types in the requirement is dependent on a non-Self
// type parameter, this requirement is okay.
if (!isSelfDerivedOrConcrete(protoSelf, req.getFirstType()) ||
!isSelfDerivedOrConcrete(protoSelf, req.getSecondType()))
continue;
// The conformance of 'Self' to the protocol is okay.
if (req.getKind() == RequirementKind::Conformance &&
req.getProtocolDecl() == proto &&
req.getFirstType()->is<GenericTypeParamType>())
continue;
ctx.Diags.diagnose(decl,
diag::requirement_restricts_self,
decl->getDescriptiveKind(), decl->getName(),
req.getFirstType().getString(),
static_cast<unsigned>(req.getKind()),
req.getSecondType().getString());
}
}
}
/// All generic parameters of a generic function must be referenced in the
/// declaration's type, otherwise we have no way to infer them.
void TypeChecker::checkReferencedGenericParams(GenericContext *dc) {
// Don't do this check for accessors: they're not used directly, so we
// never need to infer their generic arguments. This is mostly a
// compile-time optimization, but it also avoids problems with accessors
// like 'read' and 'modify' that would arise due to yields not being
// part of the formal type.
if (isa<AccessorDecl>(dc))
return;
auto *genericParams = dc->getGenericParams();
auto genericSig = dc->getGenericSignatureOfContext();
if (!genericParams)
return;
auto *decl = cast<ValueDecl>(dc->getInnermostDeclarationDeclContext());
// A helper class to collect referenced generic type parameters
// and dependent member types.
class ReferencedGenericTypeWalker : public TypeWalker {
SmallPtrSet<CanType, 4> ReferencedGenericParams;
public:
ReferencedGenericTypeWalker() {}
Action walkToTypePre(Type ty) override {
// Find generic parameters or dependent member types.
// Once such a type is found, don't recurse into its children.
if (!ty->hasTypeParameter())
return Action::SkipChildren;
if (ty->isTypeParameter()) {
ReferencedGenericParams.insert(ty->getCanonicalType());
return Action::SkipChildren;
}
return Action::Continue;
}
SmallPtrSetImpl<CanType> &getReferencedGenericParams() {
return ReferencedGenericParams;
}
};
// Collect all generic params referenced in parameter types and
// return type.
ReferencedGenericTypeWalker paramsAndResultWalker;
auto *funcTy = decl->getInterfaceType()->castTo<GenericFunctionType>();
for (const auto ¶m : funcTy->getParams())
param.getPlainType().walk(paramsAndResultWalker);
funcTy->getResult().walk(paramsAndResultWalker);
// Set of generic params referenced in parameter types,
// return type or requirements.
auto &referencedGenericParams =
paramsAndResultWalker.getReferencedGenericParams();
// Check if at least one of the generic params in the requirement refers
// to an already referenced generic parameter. If this is the case,
// then the other type is also considered as referenced, because
// it is used to put requirements on the first type.
auto reqTypesVisitor = [&referencedGenericParams](Requirement req) -> bool {
Type first;
Type second;
switch (req.getKind()) {
case RequirementKind::Superclass:
case RequirementKind::SameType:
second = req.getSecondType();
LLVM_FALLTHROUGH;
case RequirementKind::Conformance:
case RequirementKind::Layout:
first = req.getFirstType();
break;
}
// Collect generic parameter types referenced by types used in a requirement.
ReferencedGenericTypeWalker walker;
if (first && first->hasTypeParameter())
first.walk(walker);
if (second && second->hasTypeParameter())
second.walk(walker);
auto &genericParamsUsedByRequirementTypes =
walker.getReferencedGenericParams();
// If at least one of the collected generic types or a root generic
// parameter of dependent member types is known to be referenced by
// parameter types, return types or other types known to be "referenced",
// then all the types used in the requirement are considered to be
// referenced, because they are used to defined something that is known
// to be referenced.
bool foundNewReferencedGenericParam = false;
if (std::any_of(genericParamsUsedByRequirementTypes.begin(),
genericParamsUsedByRequirementTypes.end(),
[&referencedGenericParams](CanType t) {
assert(t->isTypeParameter());
return referencedGenericParams.find(
t->getRootGenericParam()
->getCanonicalType()) !=
referencedGenericParams.end();
})) {
std::for_each(genericParamsUsedByRequirementTypes.begin(),
genericParamsUsedByRequirementTypes.end(),
[&referencedGenericParams,
&foundNewReferencedGenericParam](CanType t) {
// Add only generic type parameters, but ignore any
// dependent member types, because requirement
// on a dependent member type does not provide enough
// information to infer the base generic type
// parameter.
if (!t->is<GenericTypeParamType>())
return;
if (referencedGenericParams.insert(t).second)
foundNewReferencedGenericParam = true;
});
}
return foundNewReferencedGenericParam;
};
ArrayRef<Requirement> requirements;
auto FindReferencedGenericParamsInRequirements =
[&requirements, genericSig, &reqTypesVisitor] {
requirements = genericSig.getRequirements();
// Try to find new referenced generic parameter types in requirements until
// we reach a fix point. We need to iterate until a fix point, because we
// may have e.g. chains of same-type requirements like:
// not-yet-referenced-T1 == not-yet-referenced-T2.DepType2,
// not-yet-referenced-T2 == not-yet-referenced-T3.DepType3,
// not-yet-referenced-T3 == referenced-T4.DepType4.
// When we process the first of these requirements, we don't know yet that
// T2
// will be referenced, because T3 will be referenced,
// because T3 == T4.DepType4.
while (true) {
bool foundNewReferencedGenericParam = false;
for (auto req : requirements) {
if (reqTypesVisitor(req))
foundNewReferencedGenericParam = true;
}
if (!foundNewReferencedGenericParam)
break;
}
};
// Find the depth of the function's own generic parameters.
unsigned fnGenericParamsDepth = genericParams->getParams().front()->getDepth();
// Check that every generic parameter type from the signature is
// among referencedGenericParams.
for (auto *genParam : genericSig.getGenericParams()) {
auto *paramDecl = genParam->getDecl();
if (paramDecl->getDepth() != fnGenericParamsDepth)
continue;
if (!referencedGenericParams.count(genParam->getCanonicalType())) {
// Lazily search for generic params that are indirectly used in the
// function signature. Do it only if there is a generic parameter
// that is not known to be referenced yet.
if (requirements.empty()) {
FindReferencedGenericParamsInRequirements();
// Nothing to do if this generic parameter is considered to be
// referenced after analyzing the requirements from the generic
// signature.
if (referencedGenericParams.count(genParam->getCanonicalType()))
continue;
}
// Produce an error that this generic parameter cannot be bound.
paramDecl->diagnose(diag::unreferenced_generic_parameter,
paramDecl->getNameStr());
}
}
}
///
/// Generic types
///
/// Form the interface type of an extension from the raw type and the
/// extension's list of generic parameters.
static Type formExtensionInterfaceType(
ExtensionDecl *ext, Type type,
const GenericParamList *genericParams,
SmallVectorImpl<Requirement> &sameTypeReqs,
bool &mustInferRequirements) {
if (type->is<ErrorType>())
return type;
// Find the nominal type declaration and its parent type.
if (type->is<ProtocolCompositionType>())
type = type->getCanonicalType();
// A parameterized protocol type is not a nominal. Unwrap it to get
// the underlying nominal, and record a same-type requirement for
// the primary associated type.
if (auto *paramProtoTy = type->getAs<ParameterizedProtocolType>()) {
auto *protoTy = paramProtoTy->getBaseType();
type = protoTy;
paramProtoTy->getRequirements(
protoTy->getDecl()->getSelfInterfaceType(),
sameTypeReqs);
}
Type parentType = type->getNominalParent();
GenericTypeDecl *genericDecl = type->getAnyGeneric();
// Reconstruct the parent, if there is one.
if (parentType) {
// Build the nested extension type.
auto parentGenericParams = genericDecl->getGenericParams()
? genericParams->getOuterParameters()
: genericParams;
parentType =
formExtensionInterfaceType(ext, parentType, parentGenericParams,
sameTypeReqs, mustInferRequirements);
}
// Find the nominal type.
auto nominal = dyn_cast<NominalTypeDecl>(genericDecl);
auto typealias = dyn_cast<TypeAliasDecl>(genericDecl);
if (!nominal) {
type = typealias->getUnderlyingType();
nominal = type->getNominalOrBoundGenericNominal();
}
// Form the result.
Type resultType;
SmallVector<Type, 2> genericArgs;
if (!nominal->isGeneric() || isa<ProtocolDecl>(nominal)) {
resultType = NominalType::get(nominal, parentType,
nominal->getASTContext());
} else if (genericParams) {
auto currentBoundType = type->getAs<BoundGenericType>();
// Form the bound generic type with the type parameters provided.
unsigned gpIndex = 0;
for (auto gp : *genericParams) {
SWIFT_DEFER { ++gpIndex; };
auto gpType = gp->getDeclaredInterfaceType();
genericArgs.push_back(gpType);
if (currentBoundType) {
sameTypeReqs.emplace_back(RequirementKind::SameType, gpType,
currentBoundType->getGenericArgs()[gpIndex]);
}
}
resultType = BoundGenericType::get(nominal, parentType, genericArgs);
}
// If we have a typealias, try to form type sugar.
if (typealias && TypeChecker::isPassThroughTypealias(
typealias, typealias->getUnderlyingType(), nominal)) {
auto typealiasSig = typealias->getGenericSignature();
SubstitutionMap subMap;
if (typealiasSig) {
subMap = typealiasSig->getIdentitySubstitutionMap();
mustInferRequirements = true;
}
resultType = TypeAliasType::get(typealias, parentType, subMap, resultType);
}
return resultType;
}
/// Retrieve the generic parameter depth of the extended type.
static unsigned getExtendedTypeGenericDepth(ExtensionDecl *ext) {
auto nominal = ext->getSelfNominalTypeDecl();
if (!nominal) return static_cast<unsigned>(-1);
auto sig = nominal->getGenericSignatureOfContext();
if (!sig) return static_cast<unsigned>(-1);
return sig.getGenericParams().back()->getDepth();
}
GenericSignature
GenericSignatureRequest::evaluate(Evaluator &evaluator,
GenericContext *GC) const {
auto &ctx = GC->getASTContext();
// The signature of a Protocol is trivial (Self: TheProtocol) so let's compute
// it.
if (auto PD = dyn_cast<ProtocolDecl>(GC)) {
auto self = PD->getSelfInterfaceType()->castTo<GenericTypeParamType>();
auto req =
Requirement(RequirementKind::Conformance, self,
PD->getDeclaredInterfaceType());
auto sig = GenericSignature::get({self}, {req});
// Debugging of the generic signature builder and generic signature
// generation.
if (ctx.TypeCheckerOpts.DebugGenericSignatures) {
llvm::errs() << "\n";
PD->printContext(llvm::errs());
llvm::errs() << "Generic signature: ";
PrintOptions Opts;
Opts.ProtocolQualifiedDependentMemberTypes = true;
sig->print(llvm::errs(), Opts);
llvm::errs() << "\n";
llvm::errs() << "Canonical generic signature: ";
sig.getCanonicalSignature()->print(llvm::errs(), Opts);
llvm::errs() << "\n";
}
return sig;
}
bool allowConcreteGenericParams = false;
const auto *genericParams = GC->getGenericParams();
const auto *where = GC->getTrailingWhereClause();
if (genericParams) {
// Setup the depth of the generic parameters.
const_cast<GenericParamList *>(genericParams)
->setDepth(GC->getGenericContextDepth());
// Accessors can always use the generic context of their storage
// declarations. This is a compile-time optimization since it lets us
// avoid the requirements-gathering phase, but it also simplifies that
// work for accessors which don't mention the value type in their formal
// signatures (like the read and modify coroutines, since yield types
// aren't tracked in the AST type yet).
if (auto accessor = dyn_cast<AccessorDecl>(GC->getAsDecl())) {
return cast<SubscriptDecl>(accessor->getStorage())->getGenericSignature();
}
}
// ...or we may only have a contextual where clause.
if (where) {
// If there is no generic context for the where clause to
// rely on, diagnose that now and bail out.
if (!GC->isGenericContext()) {
ctx.Diags.diagnose(where->getWhereLoc(),
GC->getParent()->isModuleScopeContext()
? diag::where_nongeneric_toplevel
: diag::where_nongeneric_ctx);
return nullptr;
}
}
if (!genericParams && where)
allowConcreteGenericParams = true;
if (!genericParams && !where) {
// We can fast-path computing the generic signature of non-generic
// declarations by re-using the parent context's signature.
if (auto accessor = dyn_cast<AccessorDecl>(GC->getAsDecl()))
if (auto subscript = dyn_cast<SubscriptDecl>(accessor->getStorage()))
return subscript->getGenericSignature();
return GC->getParentForLookup()->getGenericSignatureOfContext();
}
auto parentSig = GC->getParentForLookup()->getGenericSignatureOfContext();
SmallVector<TypeLoc, 2> inferenceSources;
SmallVector<Requirement, 2> sameTypeReqs;
if (auto VD = dyn_cast_or_null<ValueDecl>(GC->getAsDecl())) {
auto func = dyn_cast<AbstractFunctionDecl>(VD);
auto subscr = dyn_cast<SubscriptDecl>(VD);
// For functions and subscripts, resolve the parameter and result types and
// note them as inference sources.
if (subscr || func) {
const auto baseOptions =
TypeResolutionOptions(func ? TypeResolverContext::AbstractFunctionDecl
: TypeResolverContext::SubscriptDecl);
const auto resolution =
TypeResolution::forStructural(GC, baseOptions,
/*unboundTyOpener*/ nullptr,
/*placeholderHandler*/ nullptr);
auto params = func ? func->getParameters() : subscr->getIndices();
for (auto param : *params) {
auto *typeRepr = param->getTypeRepr();
if (typeRepr == nullptr)
continue;
auto paramOptions = baseOptions;
paramOptions.setContext(param->isVariadic()
? TypeResolverContext::VariadicFunctionInput
: TypeResolverContext::FunctionInput);
paramOptions |= TypeResolutionFlags::Direct;
const auto type =
resolution.withOptions(paramOptions).resolveType(typeRepr);
if (auto *specifier = dyn_cast<SpecifierTypeRepr>(typeRepr))
typeRepr = specifier->getBase();
inferenceSources.emplace_back(typeRepr, type);
}
// Gather requirements from the result type.
auto *resultTypeRepr = [&subscr, &func]() -> TypeRepr * {
if (subscr) {
return subscr->getElementTypeRepr();
} else if (auto *FD = dyn_cast<FuncDecl>(func)) {
return FD->getResultTypeRepr();
} else {
return nullptr;
}
}();
if (resultTypeRepr && !resultTypeRepr->hasOpaque()) {
const auto resultType =
resolution.withOptions(TypeResolverContext::FunctionResult)
.resolveType(resultTypeRepr);
inferenceSources.emplace_back(resultTypeRepr, resultType);
}
}
} else if (auto *ext = dyn_cast<ExtensionDecl>(GC)) {
// Form the interface type of the extension so we can use it as an inference
// source.
//
// FIXME: Push this into the "get interface type" request.
bool mustInferRequirements = false;
Type extInterfaceType =
formExtensionInterfaceType(ext, ext->getExtendedType(),
genericParams, sameTypeReqs,
mustInferRequirements);
auto cannotReuseNominalSignature = [&]() -> bool {
const auto finalDepth = genericParams->getParams().back()->getDepth();
return mustInferRequirements
|| !sameTypeReqs.empty()
|| ext->getTrailingWhereClause()
|| (getExtendedTypeGenericDepth(ext) != finalDepth);
};
// Re-use the signature of the type being extended by default.
if (!cannotReuseNominalSignature()) {
return ext->getSelfNominalTypeDecl()->getGenericSignatureOfContext();
}
// Allow parameters to be equated with concrete types.
allowConcreteGenericParams = true;
inferenceSources.emplace_back(nullptr, extInterfaceType);
}
auto request = InferredGenericSignatureRequest{
GC->getParentModule(), parentSig.getPointer(),
GC->getGenericParams(), WhereClauseOwner(GC),
sameTypeReqs, inferenceSources,
allowConcreteGenericParams};
auto sig = evaluateOrDefault(ctx.evaluator, request,
GenericSignatureWithError()).getPointer();
// Debugging of the generic signature builder and generic signature
// generation.
if (ctx.TypeCheckerOpts.DebugGenericSignatures) {
llvm::errs() << "\n";
if (auto *VD = dyn_cast_or_null<ValueDecl>(GC->getAsDecl())) {
VD->dumpRef(llvm::errs());
llvm::errs() << "\n";
} else {
GC->printContext(llvm::errs());
}
llvm::errs() << "Generic signature: ";
PrintOptions Opts;
Opts.ProtocolQualifiedDependentMemberTypes = true;
sig->print(llvm::errs(), Opts);
llvm::errs() << "\n";
llvm::errs() << "Canonical generic signature: ";
sig.getCanonicalSignature()->print(llvm::errs(), Opts);
llvm::errs() << "\n";
}
return sig;
}
///
/// Checking bound generic type arguments
///
/// Create a text string that describes the bindings of generic parameters
/// that are relevant to the given set of types, e.g.,
/// "[with T = Bar, U = Wibble]".
///
/// \param types The types that will be scanned for generic type parameters,
/// which will be used in the resulting type.
///
/// \param genericParams The generic parameters to use to resugar any
/// generic parameters that occur within the types.
///
/// \param substitutions The generic parameter -> generic argument
/// substitutions that will have been applied to these types.
/// These are used to produce the "parameter = argument" bindings in the test.
static std::string gatherGenericParamBindingsText(
ArrayRef<Type> types, TypeArrayView<GenericTypeParamType> genericParams,
TypeSubstitutionFn substitutions) {
llvm::SmallPtrSet<GenericTypeParamType *, 2> knownGenericParams;
for (auto type : types) {
if (type.isNull()) continue;
type.visit([&](Type type) {
if (auto gp = type->getAs<GenericTypeParamType>()) {
knownGenericParams.insert(
gp->getCanonicalType()->castTo<GenericTypeParamType>());
}
});
}
if (knownGenericParams.empty())
return "";
SmallString<128> result;
for (auto gp : genericParams) {
auto canonGP = gp->getCanonicalType()->castTo<GenericTypeParamType>();
if (!knownGenericParams.count(canonGP))
continue;
if (result.empty())
result += " [with ";
else
result += ", ";
result += gp->getName().str();
result += " = ";
auto type = substitutions(canonGP);
if (!type)
return "";
result += type.getString();
}
result += "]";
return result.str().str();
}
void TypeChecker::diagnoseRequirementFailure(
const CheckGenericArgumentsResult::RequirementFailureInfo &reqFailureInfo,
SourceLoc errorLoc, SourceLoc noteLoc, Type targetTy,
TypeArrayView<GenericTypeParamType> genericParams,
TypeSubstitutionFn substitutions, ModuleDecl *module) {
assert(errorLoc.isValid() && noteLoc.isValid());
const auto &req = reqFailureInfo.Req;
const auto &substReq = reqFailureInfo.SubstReq;
Diag<Type, Type, Type> diagnostic;
Diag<Type, Type, StringRef> diagnosticNote;
const auto reqKind = req.getKind();
switch (reqKind) {
case RequirementKind::Conformance: {
diagnoseConformanceFailure(substReq.getFirstType(),
substReq.getProtocolDecl(), module, errorLoc);
if (reqFailureInfo.ReqPath.empty())
return;
diagnostic = diag::type_does_not_conform_owner;
diagnosticNote = diag::type_does_not_inherit_or_conform_requirement;
break;
}
case RequirementKind::Layout:
diagnostic = diag::type_is_not_a_class;
diagnosticNote = diag::anyobject_requirement;
break;
case RequirementKind::Superclass:
diagnostic = diag::type_does_not_inherit;
diagnosticNote = diag::type_does_not_inherit_or_conform_requirement;
break;
case RequirementKind::SameType:
diagnostic = diag::types_not_equal;
diagnosticNote = diag::types_not_equal_requirement;
break;
}
Type secondTy, substSecondTy;
if (req.getKind() != RequirementKind::Layout) {
secondTy = req.getSecondType();
substSecondTy = substReq.getSecondType();
}
ASTContext &ctx = module->getASTContext();
// FIXME: Poor source-location information.
ctx.Diags.diagnose(errorLoc, diagnostic, targetTy, substReq.getFirstType(),
substSecondTy);
const auto genericParamBindingsText = gatherGenericParamBindingsText(
{req.getFirstType(), secondTy}, genericParams, substitutions);
ctx.Diags.diagnose(noteLoc, diagnosticNote, req.getFirstType(), secondTy,
genericParamBindingsText);
ParentConditionalConformance::diagnoseConformanceStack(
ctx.Diags, noteLoc, reqFailureInfo.ReqPath);
}
RequirementCheckResult TypeChecker::checkGenericArguments(
ModuleDecl *module, SourceLoc loc, SourceLoc noteLoc, Type owner,
TypeArrayView<GenericTypeParamType> genericParams,
ArrayRef<Requirement> requirements,
TypeSubstitutionFn substitutions,
SubstOptions options) {
bool valid = true;
struct RequirementSet {
ArrayRef<Requirement> Requirements;
SmallVector<ParentConditionalConformance, 4> Parents;
};
SmallVector<RequirementSet, 8> pendingReqs;
pendingReqs.push_back({requirements, {}});
ASTContext &ctx = module->getASTContext();
while (!pendingReqs.empty()) {
auto current = pendingReqs.pop_back_val();
for (const auto &rawReq : current.Requirements) {
auto req = rawReq;
if (current.Parents.empty()) {
auto substed = rawReq.subst(
substitutions, LookUpConformanceInModule(module), options);
if (!substed) {
// Another requirement will fail later; just continue.
valid = false;
continue;
}
req = *substed;
}
ArrayRef<Requirement> conditionalRequirements;
if (req.isSatisfied(conditionalRequirements, /*allowMissing=*/true)) {
if (!conditionalRequirements.empty()) {
assert(req.getKind() == RequirementKind::Conformance);
auto history = current.Parents;
history.push_back({req.getFirstType(), req.getProtocolDecl()});
pendingReqs.push_back({conditionalRequirements, std::move(history)});
}
continue;
}
if (loc.isValid()) {
Diag<Type, Type, Type> diagnostic;
Diag<Type, Type, StringRef> diagnosticNote;
switch (req.getKind()) {
case RequirementKind::Conformance: {
diagnoseConformanceFailure(req.getFirstType(), req.getProtocolDecl(),
module, loc);
if (current.Parents.empty())
return RequirementCheckResult::Failure;
diagnostic = diag::type_does_not_conform_owner;
diagnosticNote = diag::type_does_not_inherit_or_conform_requirement;
break;
}
case RequirementKind::Layout:
diagnostic = diag::type_is_not_a_class;
diagnosticNote = diag::anyobject_requirement;
break;
case RequirementKind::Superclass:
diagnostic = diag::type_does_not_inherit;
diagnosticNote = diag::type_does_not_inherit_or_conform_requirement;
break;
case RequirementKind::SameType:
diagnostic = diag::types_not_equal;
diagnosticNote = diag::types_not_equal_requirement;
break;
}
Type rawSecondType, secondType;
if (req.getKind() != RequirementKind::Layout) {
rawSecondType = rawReq.getSecondType();
secondType = req.getSecondType();
}
// FIXME: Poor source-location information.
ctx.Diags.diagnose(loc, diagnostic, owner,
req.getFirstType(), secondType);
std::string genericParamBindingsText;
if (!genericParams.empty()) {
genericParamBindingsText =
gatherGenericParamBindingsText(
{rawReq.getFirstType(), rawSecondType},
genericParams, substitutions);
}
ctx.Diags.diagnose(noteLoc, diagnosticNote,
rawReq.getFirstType(), rawSecondType,
genericParamBindingsText);
ParentConditionalConformance::diagnoseConformanceStack(
ctx.Diags, noteLoc, current.Parents);
}
return RequirementCheckResult::Failure;
}
}
if (valid)
return RequirementCheckResult::Success;
return RequirementCheckResult::SubstitutionFailure;