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[ConstraintSystem] Avoid member lookup if base type is a "hole"

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Member lookup on a "hole" is not going to produce any results
and it makes sense to detect early and short-circuit the constraint.
This commit is contained in:
Pavel Yaskevich
2019-12-04 14:23:12 -08:00
parent 805a5e9a1e
commit bbe0c098ba
1 changed files with 25 additions and 21 deletions
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46
lib/Sema/CSSimplify.cpp
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@@ -6060,20 +6060,33 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyMemberConstraint(
auto locator = getConstraintLocator(locatorB);
// If this is an unresolved member ref e.g. `.foo` and its contextual base
// type has been determined to be a "hole", let's mark the resulting member
// type as a potential hole and continue solving.
if (shouldAttemptFixes() && kind == ConstraintKind::UnresolvedValueMember &&
baseObjTy->getMetatypeInstanceType()->isHole()) {
auto *fix =
SpecifyBaseTypeForContextualMember::create(*this, member, locator);
if (recordFix(fix))
return SolutionKind::Error;
// If the base type of this member lookup is a "hole" there is no
// reason to perform a lookup because it wouldn't return any results.
if (shouldAttemptFixes()) {
auto markMemberTypeAsPotentialHole = [&](Type memberTy) {
if (auto *typeVar = memberTy->getAs<TypeVariableType>())
recordPotentialHole(typeVar);
};
if (auto *typeVar = memberTy->getAs<TypeVariableType>())
recordPotentialHole(typeVar);
// If this is an unresolved member ref e.g. `.foo` and its contextual base
// type has been determined to be a "hole", let's mark the resulting member
// type as a potential hole and continue solving.
if (kind == ConstraintKind::UnresolvedValueMember &&
baseObjTy->getMetatypeInstanceType()->isHole()) {
auto *fix =
SpecifyBaseTypeForContextualMember::create(*this, member, locator);
if (recordFix(fix))
return SolutionKind::Error;
return SolutionKind::Solved;
markMemberTypeAsPotentialHole(memberTy);
return SolutionKind::Solved;
} else if (kind == ConstraintKind::ValueMember && baseObjTy->isHole()) {
// If base type is a "hole" there is no reason to record any
// more "member not found" fixes for chained member references.
increaseScore(SK_Fix);
markMemberTypeAsPotentialHole(memberTy);
return SolutionKind::Solved;
}
}
MemberLookupResult result =
@@ -6345,15 +6358,6 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyMemberConstraint(
// fake its presence based on use, that makes it possible to diagnose
// problems related to member lookup more precisely.
// If base type is a "hole" there is no reason to record any
// more "member not found" fixes for chained member references.
if (baseTy->isHole()) {
increaseScore(SK_Fix);
if (auto *memberTypeVar = memberTy->getAs<TypeVariableType>())
recordPotentialHole(memberTypeVar);
return SolutionKind::Solved;
}
return fixMissingMember(origBaseTy, memberTy, locator);
}
return SolutionKind::Error;