Sema: Remove similar weirdness from ~ConjunctionStep

Author: slavapestov

lib/Sema/CSStep.cpp

@@ -430,10 +430,12 @@ StepResult ComponentStep::take(bool prevFailed) {
       return suspend(
           std::make_unique<DisjunctionStep>(CS, disjunction, Solutions));
     }
-    case StepKind::Conjunction:
+    case StepKind::Conjunction: {
+      CS.retireConstraint(conjunction);
       return suspend(
           std::make_unique<ConjunctionStep>(CS, conjunction, Solutions));
     }
+    }
     llvm_unreachable("Unhandled case in switch!");
   }
 

lib/Sema/CSStep.h

@@ -202,18 +202,6 @@ class SolverStep {
     return StepResult::unsolved(followup);
   }
 
-  /// Erase constraint from the constraint system (include constraint graph)
-  /// and return the constraint which follows it.
-  ConstraintList::iterator erase(Constraint *constraint) {
-    CS.CG.removeConstraint(constraint);
-    return CS.InactiveConstraints.erase(constraint);
-  }
-
-  void restore(ConstraintList::iterator &iterator, Constraint *constraint) {
-    CS.InactiveConstraints.insert(iterator, constraint);
-    CS.CG.addConstraint(constraint);
-  }
-
   void recordDisjunctionChoice(ConstraintLocator *disjunctionLocator,
                                unsigned index) const {
     CS.recordDisjunctionChoice(disjunctionLocator, index);
@@ -915,10 +903,6 @@ class ConjunctionStep : public BindingStep<ConjunctionElementProducer> {
 
   /// Conjunction constraint associated with this step.
   Constraint *Conjunction;
-  /// Position of the conjunction in the inactive constraints
-  /// list which is required to re-instate it to the system
-  /// after this step is done.
-  ConstraintList::iterator AfterConjunction;
 
   /// Indicates that one of the elements failed inference.
   bool HadFailure = false;
@@ -946,7 +930,7 @@ class ConjunctionStep : public BindingStep<ConjunctionElementProducer> {
                     conjunction->isIsolated() ? IsolatedSolutions : solutions),
         BestScore(getBestScore()),
         OuterScopeCount(cs.CountScopes, 0), Conjunction(conjunction),
-        AfterConjunction(erase(conjunction)), OuterSolutions(solutions) {
+        OuterSolutions(solutions) {
     assert(conjunction->getKind() == ConstraintKind::Conjunction);
 
     // Make a snapshot of the constraint system state before conjunction.
@@ -965,9 +949,6 @@ class ConjunctionStep : public BindingStep<ConjunctionElementProducer> {
     // Return all of the type variables and constraints back.
     Snapshot.reset();
 
-    // Restore conjunction constraint.
-    restore(AfterConjunction, Conjunction);
-
     // Restore best score only if conjunction fails because
     // successful outcome should keep a score set by `restoreOuterState`.
     if (HadFailure)