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[GSB] Pull typo correction for nested types into delayed reqs handling.

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Rather than performing typo correction at the very end of finalize(),
do it as part of delayed requirement handling when we cannot otherwise
make progress. This is a cleaner way to cope with typo correction that
gives us a better chance of getting to a sane result.

Fixes rdar://problem/31048352 by eliminating the need for tracking the
number of unresolved potential archetypes altogether. Fixes
rdar://problem/32077627.
This commit is contained in:
Doug Gregor
2017-06-19 22:40:15 -07:00
parent 4860607700
commit fe7ba8b79b
3 changed files with 98 additions and 96 deletions
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189
lib/AST/GenericSignatureBuilder.cpp
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@@ -85,11 +85,6 @@ struct GenericSignatureBuilder::Implementation {
/// The potential archetypes for the generic parameters in \c GenericParams.
SmallVector<PotentialArchetype *, 4> PotentialArchetypes;
/// The number of nested types that haven't yet been resolved to archetypes.
/// Once all requirements have been added, this will be zero in well-formed
/// code.
unsigned NumUnresolvedNestedTypes = 0;
/// The nested types that have been renamed.
SmallVector<PotentialArchetype *, 4> RenamedNestedTypes;
@@ -1099,9 +1094,6 @@ void GenericSignatureBuilder::PotentialArchetype::resolveAssociatedType(
isUnresolvedNestedType = false;
identifier.assocTypeOrConcrete = assocType;
assert(assocType->getName() == getNestedName());
assert(builder.Impl->NumUnresolvedNestedTypes > 0 &&
"Mismatch in number of unresolved nested types");
--builder.Impl->NumUnresolvedNestedTypes;
}
void GenericSignatureBuilder::PotentialArchetype::resolveConcreteType(
@@ -1111,9 +1103,6 @@ void GenericSignatureBuilder::PotentialArchetype::resolveConcreteType(
isUnresolvedNestedType = false;
identifier.assocTypeOrConcrete = concreteDecl;
assert(concreteDecl->getName() == getNestedName());
assert(builder.Impl->NumUnresolvedNestedTypes > 0 &&
"Mismatch in number of unresolved nested types");
--builder.Impl->NumUnresolvedNestedTypes;
}
Optional<ConcreteConstraint>
@@ -1214,8 +1203,6 @@ void EquivalenceClass::dump() const {
void GenericSignatureBuilder::recordUnresolvedType(
PotentialArchetype *unresolvedPA) {
++Impl->NumUnresolvedNestedTypes;
Impl->DelayedRequirements.push_back(
{DelayedRequirement::Unresolved, unresolvedPA, RequirementRHS(),
FloatingRequirementSource::forAbstract()});
@@ -2806,8 +2793,59 @@ ConstraintResult GenericSignatureBuilder::addConformanceRequirement(
return ConstraintResult::Resolved;
}
/// Perform typo correction on the given nested type, producing the
/// corrected name (if successful).
static Identifier typoCorrectNestedType(
GenericSignatureBuilder::PotentialArchetype *pa) {
StringRef name = pa->getNestedName().str();
// Look through all of the associated types of all of the protocols
// to which the parent conforms.
llvm::SmallVector<Identifier, 2> bestMatches;
unsigned bestEditDistance = 0;
unsigned maxScore = (name.size() + 1) / 3;
for (auto proto : pa->getParent()->getConformsTo()) {
for (auto member : getProtocolMembers(proto)) {
auto assocType = dyn_cast<AssociatedTypeDecl>(member);
if (!assocType)
continue;
unsigned dist = name.edit_distance(assocType->getName().str(),
/*AllowReplacements=*/true,
maxScore);
assert(dist > 0 && "nested type should have matched associated type");
if (bestEditDistance == 0 || dist == bestEditDistance) {
bestEditDistance = dist;
maxScore = bestEditDistance;
bestMatches.push_back(assocType->getName());
} else if (dist < bestEditDistance) {
bestEditDistance = dist;
maxScore = bestEditDistance;
bestMatches.clear();
bestMatches.push_back(assocType->getName());
}
}
}
// FIXME: Look through the superclass.
// If we didn't find any matches at all, fail.
if (bestMatches.empty())
return Identifier();
// Make sure that we didn't find more than one match at the best
// edit distance.
for (auto other : llvm::makeArrayRef(bestMatches).slice(1)) {
if (other != bestMatches.front())
return Identifier();
}
return bestMatches.front();
}
ConstraintResult GenericSignatureBuilder::resolveUnresolvedType(
PotentialArchetype *pa) {
PotentialArchetype *pa,
bool allowTypoCorrection) {
// If something else resolved this type, we're done.
if (!pa->isUnresolved())
return ConstraintResult::Resolved;
@@ -2828,8 +2866,31 @@ ConstraintResult GenericSignatureBuilder::resolveUnresolvedType(
return ConstraintResult::Resolved;
}
// We are unable to resolve this constraint.
return ConstraintResult::Unresolved;
// If we aren't allowed to perform typo correction, we can't resolve the
// constraint.
if (!allowTypoCorrection)
return ConstraintResult::Unresolved;
// Try to typo correct to a nested type name.
Identifier correction = typoCorrectNestedType(pa);
if (correction.empty()) {
pa->setInvalid();
return ConstraintResult::Conflicting;
}
// Note that this is being renamed.
pa->saveNameForRenaming();
Impl->RenamedNestedTypes.push_back(pa);
// Resolve the associated type and merge the potential archetypes.
auto replacement = pa->getParent()->getNestedType(correction, *this);
pa->resolveAssociatedType(replacement->getResolvedAssociatedType(),
*this);
addSameTypeRequirement(pa, replacement,
RequirementSource::forNestedTypeNameMatch(pa),
UnresolvedHandlingKind::GenerateConstraints);
return ConstraintResult::Resolved;
}
ConstraintResult GenericSignatureBuilder::addLayoutRequirementDirect(
@@ -3749,56 +3810,6 @@ void GenericSignatureBuilder::inferRequirements(
}
}
/// Perform typo correction on the given nested type, producing the
/// corrected name (if successful).
static Identifier typoCorrectNestedType(
GenericSignatureBuilder::PotentialArchetype *pa) {
StringRef name = pa->getNestedName().str();
// Look through all of the associated types of all of the protocols
// to which the parent conforms.
llvm::SmallVector<Identifier, 2> bestMatches;
unsigned bestEditDistance = 0;
unsigned maxScore = (name.size() + 1) / 3;
for (auto proto : pa->getParent()->getConformsTo()) {
for (auto member : getProtocolMembers(proto)) {
auto assocType = dyn_cast<AssociatedTypeDecl>(member);
if (!assocType)
continue;
unsigned dist = name.edit_distance(assocType->getName().str(),
/*AllowReplacements=*/true,
maxScore);
assert(dist > 0 && "nested type should have matched associated type");
if (bestEditDistance == 0 || dist == bestEditDistance) {
bestEditDistance = dist;
maxScore = bestEditDistance;
bestMatches.push_back(assocType->getName());
} else if (dist < bestEditDistance) {
bestEditDistance = dist;
maxScore = bestEditDistance;
bestMatches.clear();
bestMatches.push_back(assocType->getName());
}
}
}
// FIXME: Look through the superclass.
// If we didn't find any matches at all, fail.
if (bestMatches.empty())
return Identifier();
// Make sure that we didn't find more than one match at the best
// edit distance.
for (auto other : llvm::makeArrayRef(bestMatches).slice(1)) {
if (other != bestMatches.front())
return Identifier();
}
return bestMatches.front();
}
namespace swift {
template<typename T>
bool operator<(const Constraint<T> &lhs, const Constraint<T> &rhs) {
@@ -4104,33 +4115,6 @@ GenericSignatureBuilder::finalize(SourceLoc loc,
}
}
}
// If any nested types remain unresolved, produce diagnostics.
if (Impl->NumUnresolvedNestedTypes > 0) {
visitPotentialArchetypes([&](PotentialArchetype *pa) {
// We only care about nested types that haven't been resolved.
if (!pa->isUnresolved()) return;
// Try to typo correct to a nested type name.
Identifier correction = typoCorrectNestedType(pa);
if (correction.empty()) {
pa->setInvalid();
return;
}
// Note that this is being renamed.
pa->saveNameForRenaming();
Impl->RenamedNestedTypes.push_back(pa);
// Resolve the associated type and merge the potential archetypes.
auto replacement = pa->getParent()->getNestedType(correction, *this);
pa->resolveAssociatedType(replacement->getResolvedAssociatedType(),
*this);
addSameTypeRequirement(pa, replacement,
RequirementSource::forNestedTypeNameMatch(pa),
UnresolvedHandlingKind::GenerateConstraints);
});
}
}
bool GenericSignatureBuilder::diagnoseRemainingRenames(
@@ -4162,12 +4146,17 @@ static GenericSignatureBuilder::UnresolvedType asUnresolvedType(
void GenericSignatureBuilder::processDelayedRequirements() {
bool anySolved = !Impl->DelayedRequirements.empty();
bool allowTypoCorrection = false;
while (anySolved) {
// Steal the delayed requirements so we can reprocess them.
anySolved = false;
auto delayed = std::move(Impl->DelayedRequirements);
Impl->DelayedRequirements.clear();
// Whether we saw any unresolve type constraints that we couldn't
// resolve.
bool hasUnresolvedUnresolvedTypes = false;
// Process delayed requirements.
for (const auto &req : delayed) {
// Reprocess the delayed requirement.
@@ -4192,7 +4181,9 @@ void GenericSignatureBuilder::processDelayedRequirements() {
break;
case DelayedRequirement::Unresolved:
reqResult = resolveUnresolvedType(req.lhs.get<PotentialArchetype *>());
reqResult = resolveUnresolvedType(
req.lhs.get<PotentialArchetype *>(),
allowTypoCorrection);
break;
}
@@ -4210,9 +4201,19 @@ void GenericSignatureBuilder::processDelayedRequirements() {
case ConstraintResult::Unresolved:
// Add the requirement back.
Impl->DelayedRequirements.push_back(req);
if (req.kind == DelayedRequirement::Unresolved)
hasUnresolvedUnresolvedTypes = true;
break;
}
}
// If we didn't solve anything, but we did see some unresolved types,
// try again with typo correction enabled.
if (!anySolved && hasUnresolvedUnresolvedTypes && !allowTypoCorrection) {
allowTypoCorrection = true;
anySolved = true;
}
}
}