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ConformanceLookupTable.cpp
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//===--- ConformanceLookupTable - Conformance Lookup Table ----------------===//
//
// 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 the ConformanceLookupTable class.
//
//===----------------------------------------------------------------------===//
#include "ConformanceLookupTable.h"
#include "swift/AST/ASTContext.h"
#include "swift/AST/ConformanceLookup.h"
#include "swift/AST/Decl.h"
#include "swift/AST/ExistentialLayout.h"
#include "swift/AST/GenericParamList.h"
#include "swift/AST/LazyResolver.h"
#include "swift/AST/Module.h"
#include "swift/AST/NameLookup.h"
#include "swift/AST/SourceFile.h"
#include "swift/AST/ProtocolConformance.h"
#include "swift/AST/ProtocolConformanceRef.h"
#include "swift/AST/TypeCheckRequests.h"
#include "swift/Basic/Assertions.h"
#include "llvm/Support/SaveAndRestore.h"
using namespace swift;
DeclContext *ConformanceLookupTable::ConformanceSource::getDeclContext() const {
switch (getKind()) {
case ConformanceEntryKind::Inherited:
return getInheritingClass();
case ConformanceEntryKind::Explicit:
return getExplicitDeclContext();
case ConformanceEntryKind::Implied:
return getImpliedSource()->Source.getDeclContext();
case ConformanceEntryKind::Synthesized:
return getSynthesizedDeclContext();
case ConformanceEntryKind::PreMacroExpansion:
return getMacroGeneratedDeclContext();
}
llvm_unreachable("Unhandled ConformanceEntryKind in switch.");
}
ProtocolDecl *ConformanceLookupTable::ConformanceEntry::getProtocol() const {
if (auto protocol = Conformance.dyn_cast<ProtocolDecl *>())
return protocol;
return Conformance.get<ProtocolConformance *>()->getProtocol();
}
void ConformanceLookupTable::ConformanceEntry::markSupersededBy(
ConformanceLookupTable &table,
ConformanceEntry *entry,
bool diagnose) {
assert(!isSuperseded() && "Already superseded");
// Note that we've been superseded.
SupersededBy = entry;
if (diagnose) {
// If an unavailable Sendable conformance is superseded by a
// retroactive one in the client, we need to record this error
// at the client decl context.
auto *dc = getDeclContext();
if (getProtocol()->isMarkerProtocol() && isFixed() &&
!entry->isFixed()) {
dc = entry->getDeclContext();
}
// Record the problem in the conformance table. We'll
// diagnose these in semantic analysis.
table.AllSupersededDiagnostics[dc].push_back(this);
}
}
void ConformanceLookupTable::ConformanceEntry::dump() const {
dump(llvm::errs());
}
void ConformanceLookupTable::ConformanceEntry::dump(raw_ostream &os,
unsigned indent) const {
os.indent(indent) << "(conformance @" << static_cast<const void *>(this);
os << " protocol=";
getProtocol()->dumpRef(os);
if (Loc.isValid()) {
os << " loc=";
Loc.print(os, getProtocol()->getASTContext().SourceMgr);
}
switch (getKind()) {
case ConformanceEntryKind::Implied:
os << " implied_by=@"
<< static_cast<const void *>(Source.getImpliedSource());
break;
case ConformanceEntryKind::Explicit:
os << " explicit";
break;
case ConformanceEntryKind::Inherited:
os << " inherited";
break;
case ConformanceEntryKind::Synthesized:
os << " synthesized";
break;
case ConformanceEntryKind::PreMacroExpansion:
os << " unexpanded macro";
break;
}
if (auto conf = getConformance()) {
os << " fixed_conformance=@" << static_cast<const void *>(conf);
}
if (SupersededBy)
os << " superseded_by=@" << static_cast<const void *>(SupersededBy);
os << ")\n";
}
ConformanceLookupTable::ConformanceLookupTable(ASTContext &ctx) {
// Register a cleanup with the ASTContext to call the conformance
// table destructor.
ctx.addCleanup([this]() {
this->destroy();
});
}
void ConformanceLookupTable::destroy() {
this->~ConformanceLookupTable();
}
namespace {
struct ConformanceConstructionInfo : public Located<ProtocolDecl *> {
/// The location of the "unchecked" attribute, if present.
const SourceLoc uncheckedLoc;
/// The location of the "preconcurrency" attribute if present.
const SourceLoc preconcurrencyLoc;
ConformanceConstructionInfo() { }
ConformanceConstructionInfo(ProtocolDecl *item, SourceLoc loc,
SourceLoc uncheckedLoc,
SourceLoc preconcurrencyLoc)
: Located(item, loc), uncheckedLoc(uncheckedLoc),
preconcurrencyLoc(preconcurrencyLoc) {}
};
}
template<typename NominalFunc, typename ExtensionFunc>
void ConformanceLookupTable::forEachInStage(ConformanceStage stage,
NominalTypeDecl *nominal,
NominalFunc nominalFunc,
ExtensionFunc extensionFunc) {
assert(static_cast<unsigned>(stage) < NumConformanceStages &&
"NumConformanceStages has not been updated");
LastProcessedEntry &lastProcessed
= LastProcessed[nominal][static_cast<unsigned>(stage)];
// Handle the nominal type.
if (!lastProcessed.getInt()) {
lastProcessed.setInt(true);
// If we have conformances we can load, do so.
// FIXME: This could be lazier.
auto loader = nominal->takeConformanceLoader();
if (loader.first) {
SmallVector<ProtocolConformance *, 2> conformances;
loader.first->loadAllConformances(nominal, loader.second, conformances);
registerProtocolConformances(nominal, conformances);
}
nominalFunc(nominal);
}
// Protocol extensions do not contribute protocol conformances. This
// is enforced by semantic analysis, so the early exit here is a
// performance optimization and also prevents us from erroneously
// including those protocols before they get diagnosed.
if (isa<ProtocolDecl>(nominal))
return;
// Handle the extensions that we have not yet visited.
nominal->prepareExtensions();
while (auto next = lastProcessed.getPointer()
? lastProcessed.getPointer()->NextExtension.getPointer()
: nominal->FirstExtension) {
lastProcessed.setPointer(next);
SmallVector<ConformanceConstructionInfo, 2> protocols;
// If we have conformances we can load, do so.
// FIXME: This could be lazier.
auto loader = next->takeConformanceLoader();
if (loader.first) {
SmallVector<ProtocolConformance *, 2> conformances;
loader.first->loadAllConformances(next, loader.second, conformances);
registerProtocolConformances(next, conformances);
for (auto conf : conformances) {
protocols.push_back(
{conf->getProtocol(), SourceLoc(), SourceLoc(), SourceLoc()});
}
} else if (next->getParentSourceFile() ||
next->getParentModule()->isBuiltinModule()) {
InvertibleProtocolSet inverses;
bool anyObject = false;
for (const auto &found :
getDirectlyInheritedNominalTypeDecls(next, inverses, anyObject)) {
if (auto proto = dyn_cast<ProtocolDecl>(found.Item))
protocols.push_back(
{proto, found.Loc, found.uncheckedLoc, found.preconcurrencyLoc});
}
}
extensionFunc(next, protocols);
}
}
void ConformanceLookupTable::inheritConformances(ClassDecl *classDecl,
ClassDecl *superclassDecl,
ExtensionDecl *superclassExt) {
// Local function to return the location of the superclass. This
// takes a little digging, so compute on first use and cache it.
SourceLoc superclassLoc;
auto getSuperclassLoc = [&] {
if (superclassLoc.isValid())
return superclassLoc;
auto inheritedTypes = classDecl->getInherited();
for (unsigned i : inheritedTypes.getIndices()) {
if (auto inheritedType = inheritedTypes.getEntry(i).getType()) {
if (inheritedType->getClassOrBoundGenericClass()) {
superclassLoc = inheritedTypes.getEntry(i).getSourceRange().Start;
return superclassLoc;
}
if (inheritedType->isExistentialType()) {
auto layout = inheritedType->getExistentialLayout();
if (layout.explicitSuperclass) {
superclassLoc = inheritedTypes.getEntry(i).getSourceRange().Start;
return superclassLoc;
}
}
}
}
superclassLoc = superclassDecl->getLoc();
return superclassLoc;
};
llvm::SmallPtrSet<ProtocolDecl *, 4> protocols;
auto addInheritedConformance = [&](ConformanceEntry *entry) {
auto protocol = entry->getProtocol();
// Don't add redundant conformances here. This is merely an
// optimization; resolveConformances() would zap the duplicates
// anyway.
if (!protocols.insert(protocol).second)
return;
// Add the inherited entry.
(void)addProtocol(protocol, getSuperclassLoc(),
ConformanceSource::forInherited(classDecl));
};
// Add inherited conformances.
DeclContext *superDC = superclassExt;
if (!superclassExt)
superDC = superclassDecl;
for (auto entry : superclassDecl->ConformanceTable->AllConformances[superDC]){
addInheritedConformance(entry);
}
}
void ConformanceLookupTable::updateLookupTable(NominalTypeDecl *nominal,
ConformanceStage stage) {
switch (stage) {
case ConformanceStage::RecordedExplicit:
// Record all of the explicit conformances.
forEachInStage(
stage, nominal,
[&](NominalTypeDecl *nominal) {
auto source = ConformanceSource::forExplicit(nominal);
// Get all of the protocols in the inheritance clause.
InvertibleProtocolSet inverses;
bool anyObject = false;
for (const auto &found :
getDirectlyInheritedNominalTypeDecls(nominal, inverses, anyObject)) {
auto proto = dyn_cast<ProtocolDecl>(found.Item);
if (!proto)
continue;
auto kp = proto->getKnownProtocolKind();
assert(!found.isSuppressed ||
kp.has_value() &&
"suppressed conformance for non-known protocol!?");
if (!found.isSuppressed) {
addProtocol(proto, found.Loc,
source.withUncheckedLoc(found.uncheckedLoc)
.withPreconcurrencyLoc(found.preconcurrencyLoc));
}
}
addMacroGeneratedProtocols(
nominal, ConformanceSource::forUnexpandedMacro(nominal));
},
[&](ExtensionDecl *ext, ArrayRef<ConformanceConstructionInfo> protos) {
// The extension decl may not be validated, so we can't use
// its inherited protocols directly.
auto source = ConformanceSource::forExplicit(ext);
for (auto locAndProto : protos)
addProtocol(
locAndProto.Item, locAndProto.Loc,
source.withUncheckedLoc(locAndProto.uncheckedLoc)
.withPreconcurrencyLoc(locAndProto.preconcurrencyLoc));
});
break;
case ConformanceStage::Inherited:
updateLookupTable(nominal, ConformanceStage::RecordedExplicit);
// For classes, expand implied conformances of the superclass,
// because an implied conformance in the superclass is considered
// "fixed" in the subclass.
if (auto classDecl = dyn_cast<ClassDecl>(nominal)) {
if (auto superclassDecl = classDecl->getSuperclassDecl()) {
// Break infinite recursion when visiting ill-formed classes
// with circular inheritance.
if (VisitingSuperclass)
return;
llvm::SaveAndRestore<bool> visiting(VisitingSuperclass, true);
// Don't update our own lookup table if we inherit from ourselves.
if (classDecl == superclassDecl)
break;
// Resolve the conformances of the superclass.
superclassDecl->prepareConformanceTable();
superclassDecl->ConformanceTable->updateLookupTable(
superclassDecl,
ConformanceStage::Resolved);
// Expand inherited conformances from all superclasses.
// We may have circular inheritance in ill-formed classes, so keep an
// eye out for that.
auto circularSuperclass = superclassDecl->getSuperclassDecl();
do {
forEachInStage(
stage, superclassDecl,
[&](NominalTypeDecl *superclass) {
inheritConformances(classDecl, superclassDecl, nullptr);
},
[&](ExtensionDecl *ext,
ArrayRef<ConformanceConstructionInfo> protos) {
(void)protos;
inheritConformances(classDecl, superclassDecl, ext);
});
superclassDecl = superclassDecl->getSuperclassDecl();
if (circularSuperclass)
circularSuperclass = circularSuperclass->getSuperclassDecl();
if (circularSuperclass)
circularSuperclass = circularSuperclass->getSuperclassDecl();
} while (superclassDecl != circularSuperclass);
}
}
break;
case ConformanceStage::ExpandedImplied:
// Record explicit conformances and import inherited conformances
// before expanding.
updateLookupTable(nominal, ConformanceStage::Inherited);
// Expand inherited conformances.
forEachInStage(
stage, nominal,
[&](NominalTypeDecl *nominal) {
expandImpliedConformances(nominal, nominal);
},
[&](ExtensionDecl *ext,
ArrayRef<ConformanceConstructionInfo> protos) {
(void)protos;
expandImpliedConformances(nominal, ext);
});
break;
case ConformanceStage::Resolved:
// Expand inherited conformances so we have the complete set of
// conformances.
updateLookupTable(nominal, ConformanceStage::ExpandedImplied);
/// Determine whether any extensions were added that might require
/// us to compute conformances again.
bool anyChanged = false;
forEachInStage(stage, nominal,
[&](NominalTypeDecl *nominal) { anyChanged = true; },
[&](ExtensionDecl *ext,
ArrayRef<ConformanceConstructionInfo>) {
anyChanged = true;
});
if (anyChanged) {
// Compute the conformances for each protocol.
bool anySuperseded = false;
for (const auto &entry : Conformances) {
if (resolveConformances(entry.first))
anySuperseded = true;
}
if (anySuperseded) {
// Update the lists of all conformances to remove superseded
// conformances.
for (auto &conformances : AllConformances) {
conformances.second.erase(
std::remove_if(conformances.second.begin(),
conformances.second.end(),
[&](ConformanceEntry *entry) {
return entry->isSuperseded();
}),
conformances.second.end());
}
}
}
break;
}
}
void ConformanceLookupTable::registerProtocolConformances(
DeclContext *dc,
ArrayRef<ProtocolConformance*> conformances) {
// If this declaration context came from source, there's nothing to
// do here.
assert(!dc->getParentSourceFile() &&
!dc->getParentModule()->isBuiltinModule());
// Add entries for each loaded conformance.
for (auto conformance : conformances) {
registerProtocolConformance(dc, conformance);
}
}
bool ConformanceLookupTable::addProtocol(ProtocolDecl *protocol, SourceLoc loc,
ConformanceSource source) {
DeclContext *dc = source.getDeclContext();
ASTContext &ctx = dc->getASTContext();
// Determine the kind of conformance.
ConformanceEntryKind kind = source.getKind();
// If this entry is synthesized or implied, scan to determine
// whether there are any explicit better conformances that make this
// conformance trivially superseded (and, therefore, not worth
// recording).
auto &conformanceEntries = Conformances[protocol];
if (kind == ConformanceEntryKind::Implied ||
kind == ConformanceEntryKind::Synthesized) {
for (const auto *existingEntry : conformanceEntries) {
switch (existingEntry->getKind()) {
case ConformanceEntryKind::Explicit:
case ConformanceEntryKind::Inherited:
case ConformanceEntryKind::PreMacroExpansion:
return false;
case ConformanceEntryKind::Implied:
// Ignore implied circular protocol inheritance
if (existingEntry->getDeclContext() == dc)
return false;
// An implied conformance is better than a synthesized one, unless
// the implied conformance was deserialized.
if (kind == ConformanceEntryKind::Synthesized &&
existingEntry->getDeclContext()->getParentSourceFile() == nullptr)
return false;
break;
case ConformanceEntryKind::Synthesized:
// An implied conformance is better unless it was deserialized.
if (dc->getParentSourceFile() == nullptr)
return false;
break;
}
}
}
/// Build the conformance entry (if it hasn't been built before).
ConformanceEntry *entry = new (ctx) ConformanceEntry(loc, protocol, source);
conformanceEntries.push_back(entry);
// Record this as a conformance within the given declaration
// context.
AllConformances[dc].push_back(entry);
return true;
}
void ConformanceLookupTable::addMacroGeneratedProtocols(
NominalTypeDecl *nominal, ConformanceSource source) {
nominal->forEachAttachedMacro(
MacroRole::Extension,
[&](CustomAttr *attr, MacroDecl *macro) {
SmallVector<ProtocolDecl *, 2> conformances;
macro->getIntroducedConformances(
nominal, MacroRole::Extension, conformances);
for (auto *protocol : conformances) {
addProtocol(protocol, attr->getLocation(), source);
}
});
}
void ConformanceLookupTable::expandImpliedConformances(NominalTypeDecl *nominal,
DeclContext *dc) {
ASTContext &ctx = nominal->getASTContext();
// Note: recursive type-checking implies that AllConformances
// may be reallocated during this traversal, so pay the lookup cost
// during each iteration.
for (unsigned i = 0; i != AllConformances[dc].size(); ++i) {
/// FIXME: Avoid the possibility of an infinite loop by fixing the root
/// cause instead (incomplete circularity detection).
assert(i <= 16384 &&
"Infinite loop due to circular protocol inheritance?");
ConformanceEntry *conformanceEntry = AllConformances[dc][i];
ProtocolDecl *conformingProtocol = conformanceEntry->getProtocol();
// An @objc enum that explicitly conforms to the Error protocol
// also implicitly conforms to _ObjectiveCBridgeableError, via the
// known protocol _BridgedNSError.
if (conformingProtocol->isSpecificProtocol(
KnownProtocolKind::Error) &&
isa<EnumDecl>(nominal) && nominal->isObjC() &&
cast<EnumDecl>(nominal)->hasCases() &&
cast<EnumDecl>(nominal)->hasOnlyCasesWithoutAssociatedValues()) {
if (auto bridgedNSError
= ctx.getProtocol(KnownProtocolKind::BridgedNSError)) {
addProtocol(bridgedNSError, SourceLoc(),
ConformanceSource::forImplied(conformanceEntry));
}
}
auto source = ConformanceSource::forImplied(conformanceEntry);
for (auto *inherited : conformingProtocol->getInheritedProtocols()) {
// Conforming a ~Copyable nominal to a protocol that inherits Copyable
// should not imply a Copyable conformance on the nominal.
if (inherited->getInvertibleProtocolKind())
continue;
addProtocol(inherited, SourceLoc(), source);
}
}
}
/// Determine whether the given conformance entry kind can be replaced.
static bool isReplaceable(ConformanceEntryKind kind) {
switch (kind) {
case ConformanceEntryKind::Implied:
case ConformanceEntryKind::Synthesized:
case ConformanceEntryKind::PreMacroExpansion:
return true;
case ConformanceEntryKind::Explicit:
case ConformanceEntryKind::Inherited:
return false;
}
llvm_unreachable("Unhandled ConformanceEntryKind in switch.");
}
ConformanceLookupTable::Ordering ConformanceLookupTable::compareConformances(
ConformanceEntry *lhs,
ConformanceEntry *rhs,
bool &diagnoseSuperseded) {
ConformanceEntryKind lhsKind = lhs->getRankingKind();
ConformanceEntryKind rhsKind = rhs->getRankingKind();
// Pre-expanded macro conformances are always superseded by
// conformances written in source. If the conformance is not
// written in the original source, the pre-expanded conformance
// will be superseded by the conformance in the macro expansion
// buffer.
if (lhsKind == ConformanceEntryKind::PreMacroExpansion ||
rhsKind == ConformanceEntryKind::PreMacroExpansion) {
if (lhsKind != rhsKind) {
return (lhs->getKind() < rhs->getKind()
? Ordering::Before
: Ordering::After);
}
}
// If only one of the conformances is unconditionally available on the
// current deployment target, pick that one.
//
// FIXME: Conformance lookup should really depend on source location for
// this to be 100% correct.
// FIXME: When a class and an extension with the same availability declare the
// same conformance, this silently takes the class and drops the extension.
if (lhs->getDeclContext()->isAlwaysAvailableConformanceContext() !=
rhs->getDeclContext()->isAlwaysAvailableConformanceContext()) {
// Diagnose conflicting marker protocol conformances that differ in
// un-availability.
diagnoseSuperseded = lhs->getProtocol()->isMarkerProtocol();
return (lhs->getDeclContext()->isAlwaysAvailableConformanceContext()
? Ordering::Before
: Ordering::After);
}
// If one entry is fixed and the other is not, we have our answer.
if (lhs->isFixed() != rhs->isFixed()) {
// If the non-fixed conformance is not replaceable, we have a failure to
// diagnose.
// FIXME: We should probably diagnose if they have different constraints.
diagnoseSuperseded = (lhs->isFixed() && !isReplaceable(rhs->getRankingKind())) ||
(rhs->isFixed() && !isReplaceable(lhs->getRankingKind()));
return lhs->isFixed() ? Ordering::Before : Ordering::After;
}
if (lhsKind != ConformanceEntryKind::Implied ||
rhsKind != ConformanceEntryKind::Implied) {
// If both conformances are non-replaceable, diagnose the
// superseded one.
diagnoseSuperseded = !isReplaceable(lhsKind) && !isReplaceable(rhsKind) &&
!(lhsKind == ConformanceEntryKind::Inherited &&
rhsKind == ConformanceEntryKind::Inherited);
// If we can order by kind, do so.
if (lhsKind != rhsKind) {
return (static_cast<unsigned>(lhsKind) < static_cast<unsigned>(rhsKind))
? Ordering::Before
: Ordering::After;
}
// We shouldn't get two synthesized conformances. It's not harmful
// per se, but it's indicative of redundant logic in the frontend.
assert((lhs->getKind() != ConformanceEntryKind::Synthesized ||
rhs->getKind() != ConformanceEntryKind::Synthesized) &&
"Shouldn't ever get two truly synthesized conformances");
// FIXME: Deterministic ordering.
return Ordering::Before;
}
// Both the left- and right-hand sides are implied, so determine where the
// conformance should go.
assert(lhsKind == ConformanceEntryKind::Implied &&
"Expected implied conformance");
assert(rhsKind == ConformanceEntryKind::Implied &&
"Expected implied conformance");
diagnoseSuperseded = false;
// First, try to use the stated explicit conformances to determine where the
// conformance should go.
auto lhsExplicit = lhs->getDeclaredConformance();
auto lhsExplicitProtocol = lhsExplicit->getProtocol();
auto rhsExplicit = rhs->getDeclaredConformance();
auto rhsExplicitProtocol = rhsExplicit->getProtocol();
if (lhsExplicitProtocol != rhsExplicitProtocol) {
// If the explicit protocol for the left-hand side is implied by
// the explicit protocol for the right-hand side, the left-hand
// side supersedes the right-hand side.
if (rhsExplicitProtocol->inheritsFrom(lhsExplicitProtocol))
return Ordering::Before;
// If the explicit protocol for the right-hand side is implied by
// the explicit protocol for the left-hand side, the right-hand
// side supersedes the left-hand side.
if (lhsExplicitProtocol->inheritsFrom(rhsExplicitProtocol))
return Ordering::After;
}
// Prefer the least conditional implier, which we approximate by seeing if one
// of the contexts syntactically has no generic requirements. This misses
// redundant cases like `struct Foo<T: P> {} extension Foo: P where T: P {}`
// (Foo : P is unconditional), but isConstrainedExtension doesn't fly as it
// requires the generic signature of the extension to exist, which requires
// conformances to exist, which is what we're doing here.
auto hasAdditionalRequirements = [&](ConformanceEntry *entry) {
if (auto ED = dyn_cast<ExtensionDecl>(entry->getDeclContext()))
if (auto TWC = ED->getTrailingWhereClause())
return !TWC->getRequirements().empty();
return false;
};
bool lhsHasReqs = hasAdditionalRequirements(lhs);
bool rhsHasReqs = hasAdditionalRequirements(rhs);
if (lhsHasReqs != rhsHasReqs)
return lhsHasReqs ? Ordering::After : Ordering::Before;
// If the two conformances come from the same file, pick the first context
// in the file.
auto lhsSF = lhs->getDeclContext()->getParentSourceFile();
auto rhsSF = rhs->getDeclContext()->getParentSourceFile();
if (lhsSF && lhsSF == rhsSF) {
ASTContext &ctx = lhsSF->getASTContext();
return ctx.SourceMgr.isBeforeInBuffer(lhs->getDeclaredLoc(),
rhs->getDeclaredLoc())
? Ordering::Before
: Ordering::After;
}
// If one of the conformances comes from the same file as the type
// declaration, pick that one; this is so that conformance synthesis works if
// there's any implied conformance in the same file as the type.
auto NTD = lhs->getDeclContext()->getSelfNominalTypeDecl();
auto typeSF = NTD->getParentSourceFile();
if (typeSF) {
if (typeSF == lhsSF)
return Ordering::Before;
if (typeSF == rhsSF)
return Ordering::After;
}
// Otherwise, pick the earlier file unit.
auto lhsFileUnit
= dyn_cast<FileUnit>(lhs->getDeclContext()->getModuleScopeContext());
auto rhsFileUnit
= dyn_cast<FileUnit>(rhs->getDeclContext()->getModuleScopeContext());
assert(lhsFileUnit && rhsFileUnit && "Not from a file unit?");
if (lhsFileUnit == rhsFileUnit) {
// If the file units are the same, just pick arbitrarily; we're not
// actually emitting anything.
// FIXME: Only because we're synthesizing conformances for deserialized
// protocols. Once that's no longer true (because we're serializing
// everything appropriately in the module), we should assert that this
// does not happen.
assert(!lhsSF && !rhsSF && "Source files shouldn't conflict");
return Ordering::Before;
}
auto module = lhs->getDeclContext()->getParentModule();
assert(lhs->getDeclContext()->getParentModule()
== rhs->getDeclContext()->getParentModule() &&
"conformances should be in the same module");
for (auto file : module->getFiles()) {
if (file == lhsFileUnit)
return Ordering::Before;
if (file == rhsFileUnit)
return Ordering::After;
}
llvm_unreachable("files weren't in the parent module?");
}
bool ConformanceLookupTable::resolveConformances(ProtocolDecl *protocol) {
// Find any entries that are superseded by other entries.
ConformanceEntries &entries = Conformances[protocol];
llvm::SmallPtrSet<DeclContext *, 4> knownConformances;
bool anySuperseded = false;
for (auto entry : entries) {
// If this entry has a conformance associated with it, note that.
if (entry->getConformance())
knownConformances.insert(entry->getDeclContext());
// If this entry was superseded, move on.
if (entry->isSuperseded()) {
anySuperseded = true;
continue;
}
// Determine whether this entry is superseded by (or supersedes)
// some other entry.
for (auto otherEntry : entries) {
if (entry == otherEntry)
continue;
if (otherEntry->isSuperseded()) {
anySuperseded = true;
continue;
}
bool diagnoseSuperseded = false;
bool doneWithEntry = false;
switch (compareConformances(entry, otherEntry, diagnoseSuperseded)) {
case Ordering::Equivalent:
break;
case Ordering::Before:
otherEntry->markSupersededBy(*this, entry, diagnoseSuperseded);
anySuperseded = true;
break;
case Ordering::After:
entry->markSupersededBy(*this, otherEntry, diagnoseSuperseded);
anySuperseded = true;
doneWithEntry = true;
break;
}
if (doneWithEntry)
break;
}
}
// If any entries were superseded, remove them now.
if (anySuperseded) {
entries.erase(std::remove_if(entries.begin(), entries.end(),
[&](ConformanceEntry *entry) {
return entry->isSuperseded();
}),
entries.end());
}
return anySuperseded;
}
DeclContext *ConformanceLookupTable::getConformingContext(
NominalTypeDecl *nominal,
ConformanceEntry *entry) {
ProtocolDecl *protocol = entry->getProtocol();
// Dig through the inherited entries to find a non-inherited one.
// Handle recursive inheritance.
SmallPtrSet<ClassDecl *, 4> visited;
while (entry->getKind() == ConformanceEntryKind::Inherited) {
// Make sure we have an up-to-date conformance table for the
// superclass.
auto classDecl = cast<ClassDecl>(nominal);
if (!visited.insert(classDecl).second)
return nullptr;
// If we had a circular dependency, the superclass may not exist.
auto superclassDecl
= classDecl->getSuperclassDecl();
if (!superclassDecl)
return nullptr;
if (!classDecl->ConformanceTable->VisitingSuperclass) {
llvm::SaveAndRestore<bool> visiting(
classDecl->ConformanceTable
->VisitingSuperclass,
true);
superclassDecl->prepareConformanceTable();
superclassDecl->ConformanceTable->resolveConformances(protocol);
}
// Grab the superclass entry and continue searching for a
// non-inherited conformance.
// FIXME: Ambiguity detection and resolution.
const auto &superclassConformances =
superclassDecl->ConformanceTable->Conformances[protocol];
if (superclassConformances.empty()) {
assert(protocol->isSpecificProtocol(KnownProtocolKind::Sendable) ||
protocol->isSpecificProtocol(KnownProtocolKind::Copyable));
// Go dig for a superclass that does conform to Sendable.
// FIXME: This is a hack because the inherited conformances aren't
// getting updated properly.
Type classTy = nominal->getDeclaredInterfaceType();
do {
Type superclassTy = classTy->getSuperclassForDecl(superclassDecl);
if (superclassTy->is<ErrorType>())
return nullptr;
auto inheritedConformance = swift::lookupConformance(
superclassTy, protocol, /*allowMissing=*/false);
if (inheritedConformance)
return superclassDecl;
} while ((superclassDecl = superclassDecl->getSuperclassDecl()));
return nullptr;
}
entry = superclassConformances.front();
nominal = superclassDecl;
}
return entry->getDeclContext();
}
ProtocolConformance *
ConformanceLookupTable::getConformance(NominalTypeDecl *nominal,
ConformanceEntry *entry) {
// If we already have a conformance, we're done.
if (auto conformance = entry->getConformance())
return conformance;
ProtocolDecl *protocol = entry->getProtocol();
// Determine where the explicit conformance actually lives.
// FIXME: This is a hack to ensure that inherited conformances are
// always "single step", which is bad for resilience but is assumed
// elsewhere in the compiler.
DeclContext *conformingDC = getConformingContext(nominal, entry);
if (!conformingDC)
return nullptr;
// Never produce a conformance for a pre-macro-expansion conformance. They
// are placeholders that will be superseded.
if (entry->getKind() == ConformanceEntryKind::PreMacroExpansion) {
if (auto supersedingEntry = entry->SupersededBy) {
return getConformance(nominal, supersedingEntry);
}
return nullptr;
}
auto *conformingNominal = conformingDC->getSelfNominalTypeDecl();
// Form the conformance.
Type type = entry->getDeclContext()->getDeclaredInterfaceType();
ASTContext &ctx = nominal->getASTContext();
if (protocol->getInvertibleProtocolKind() &&
entry->getDeclContext() == nominal &&
(entry->getKind() == ConformanceEntryKind::Synthesized ||
entry->getKind() == ConformanceEntryKind::Inherited)) {
// Unconditional conformances to Copyable and Escapable are represented as
// builtin conformances, which do not need to store a substitution map.
//
// This avoids an exponential blowup when constructing the context
// substitution map for a type like G<G<G<G<...>>>>.
Type conformingType = nominal->getSelfInterfaceType();
entry->Conformance = ctx.getBuiltinConformance(
conformingType, protocol, BuiltinConformanceKind::Synthesized);
} else if (entry->getKind() == ConformanceEntryKind::Inherited) {
// For an inherited conformance, the conforming nominal type will
// be different from the nominal type.
assert(conformingNominal != nominal && "Broken inherited conformance");
// Find the superclass type that matches where the conformance was
// declared.
auto *conformingClass = cast<ClassDecl>(conformingNominal);
Type superclassTy = type->getSuperclassForDecl(conformingClass);
if (superclassTy->is<ErrorType>())
return nullptr;
// Look up the inherited conformance.
auto inheritedConformance = swift::lookupConformance(
superclassTy, protocol, /*allowMissing=*/true);
// Form the inherited conformance.
entry->Conformance =
ctx.getInheritedConformance(type, inheritedConformance.getConcrete());
} else {
// Protocols don't have conformance lookup tables. Self-conformance is
// handled directly in lookupConformance().
assert(!isa<ProtocolDecl>(conformingNominal));
assert(!isa<ProtocolDecl>(conformingDC->getSelfNominalTypeDecl()));
Type conformingType = conformingDC->getSelfInterfaceType();
SourceLoc conformanceLoc =
entry->getLoc().isValid() ? entry->getLoc()
: (conformingNominal == conformingDC
? conformingNominal->getLoc()
: cast<ExtensionDecl>(conformingDC)->getLoc());
NormalProtocolConformance *implyingConf = nullptr;
if (entry->Source.getKind() == ConformanceEntryKind::Implied) {
auto implyingEntry = entry->Source.getImpliedSource();
auto origImplyingConf = getConformance(conformingNominal, implyingEntry);
if (!origImplyingConf)
return nullptr;
implyingConf = origImplyingConf->getRootNormalConformance();
}
// Create or find the normal conformance.
auto normalConf = ctx.getNormalConformance(
conformingType, protocol, conformanceLoc, conformingDC,
ProtocolConformanceState::Incomplete,
entry->Source.getUncheckedLoc().isValid(),
entry->Source.getPreconcurrencyLoc().isValid(),
entry->Source.getPreconcurrencyLoc());
// Invalid code may cause the getConformance call below to loop, so break
// the infinite recursion by setting this eagerly to shortcircuit with the
// early return at the start of this function.
entry->Conformance = normalConf;
normalConf->setSourceKindAndImplyingConformance(entry->Source.getKind(),
implyingConf);
// If the conformance was synthesized by the ClangImporter, give it a
// lazy loader that will be used to populate the conformance.
// First, if this is a conformance to a base protocol of a derived
// protocol, find the most derived protocol.
auto *impliedEntry = entry;