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Sema: Fix ordering of constraint graph updates vs fixed type assignment

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This commit is contained in:
Slava Pestov
2024-10-22 16:56:29 -04:00
parent 0d3d31599f
commit 5690addb4e
3 changed files with 46 additions and 6 deletions
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36
lib/Sema/ConstraintGraph.cpp
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@@ -352,6 +352,36 @@ void ConstraintGraphNode::retractFromInference(Constraint *constraint) {
}
}
void ConstraintGraphNode::retractFromInference(Type fixedType) {
// Notify all of the type variables that reference this one.
//
// Since this type variable has been replaced with a fixed type
// all of the concrete types that reference it are going to change,
// which means that all of the not-yet-attempted bindings should
// change as well.
notifyReferencingVars(
[&](ConstraintGraphNode &node, Constraint *constraint) {
node.retractFromInference(constraint);
});
if (!fixedType->hasTypeVariable())
return;
SmallPtrSet<TypeVariableType *, 4> referencedVars;
fixedType->getTypeVariables(referencedVars);
for (auto *referencedVar : referencedVars) {
auto &node = CG[referencedVar];
// Newly referred vars need to re-introduce all constraints associated
// with this type variable since they are now going to be used in
// all of the constraints that reference bound type variable.
for (auto *constraint : getConstraints()) {
if (isUsefulForReferencedVars(constraint))
node.retractFromInference(constraint);
}
}
}
void ConstraintGraphNode::introduceToInference(Type fixedType) {
// Notify all of the type variables that reference this one.
@@ -362,7 +392,6 @@ void ConstraintGraphNode::introduceToInference(Type fixedType) {
// change as well.
notifyReferencingVars(
[&](ConstraintGraphNode &node, Constraint *constraint) {
node.retractFromInference(constraint);
node.introduceToInference(constraint);
});
@@ -380,7 +409,6 @@ void ConstraintGraphNode::introduceToInference(Type fixedType) {
// all of the constraints that reference bound type variable.
for (auto *constraint : getConstraints()) {
if (isUsefulForReferencedVars(constraint)) {
node.retractFromInference(constraint);
node.introduceToInference(constraint);
}
}
@@ -548,6 +576,10 @@ void ConstraintGraph::bindTypeVariable(TypeVariableType *typeVar, Type fixed) {
}
}
void ConstraintGraph::retractFromInference(TypeVariableType *typeVar, Type fixed) {
(*this)[typeVar].retractFromInference(fixed);
}
void ConstraintGraph::introduceToInference(TypeVariableType *typeVar, Type fixed) {
(*this)[typeVar].introduceToInference(fixed);
}