[CS] Remove ConstraintSystemPhase

Author: hamishknight

include/swift/Sema/ConstraintSystem.h

@@ -2129,11 +2129,6 @@ class SyntacticElementTargetRewriter {
   virtual ~SyntacticElementTargetRewriter() = default;
 };
 
-enum class ConstraintSystemPhase {
-  ConstraintGeneration,
-  Solving
-};
-
 /// Retrieve the closure type from the constraint system.
 struct GetClosureType {
   ConstraintSystem &cs;
@@ -2195,9 +2190,6 @@ class ConstraintSystem {
   /// Do not set directly, call \c recordFailedConstraint instead.
   Constraint *failedConstraint = nullptr;
 
-  /// Current phase of the constraint system lifetime.
-  ConstraintSystemPhase Phase = ConstraintSystemPhase::ConstraintGeneration;
-
   /// The set of expressions for which we have generated constraints.
   llvm::SetVector<Expr *> InputExprs;
 
@@ -2675,30 +2667,6 @@ class ConstraintSystem {
   /// \c nullptr if no constraint has failed.
   Constraint *getFailedConstraint() const { return failedConstraint; }
 
-  ConstraintSystemPhase getPhase() const { return Phase; }
-
-  /// Move constraint system to a new phase of its lifetime.
-  void setPhase(ConstraintSystemPhase newPhase) {
-    if (Phase == newPhase)
-      return;
-
-#ifndef NDEBUG
-    switch (Phase) {
-    case ConstraintSystemPhase::ConstraintGeneration:
-      assert(newPhase == ConstraintSystemPhase::Solving);
-      break;
-
-    case ConstraintSystemPhase::Solving:
-      // We can come back to constraint generation phase while
-      // processing result builder body.
-      assert(newPhase == ConstraintSystemPhase::ConstraintGeneration);
-      break;
-    }
-#endif
-
-    Phase = newPhase;
-  }
-
   /// Check whether constraint system is in valid state e.g.
   /// has left-over active/inactive constraints which should
   /// have been simplified.
@@ -3906,7 +3874,7 @@ class ConstraintSystem {
     // Add this constraint to the constraint graph.
     CG.addConstraint(constraint);
 
-    if (isDebugMode() && getPhase() == ConstraintSystemPhase::Solving) {
+    if (isDebugMode() && solverState) {
       auto &log = llvm::errs();
       log.indent(solverState->getCurrentIndent() + 4) << "(added constraint: ";
       constraint->print(log, &getASTContext().SourceMgr,
@@ -3927,7 +3895,7 @@ class ConstraintSystem {
     if (solverState)
       recordChange(SolverTrail::Change::RetiredConstraint(where, constraint));
 
-    if (isDebugMode() && getPhase() == ConstraintSystemPhase::Solving) {
+    if (isDebugMode() && solverState) {
       auto &log = llvm::errs();
       log.indent(solverState->getCurrentIndent() + 4)
           << "(removed constraint: ";

lib/Sema/CSGen.cpp

@@ -944,7 +944,6 @@ namespace {
   class ConstraintGenerator : public ExprVisitor<ConstraintGenerator, Type> {
     ConstraintSystem &CS;
     DeclContext *CurDC;
-    ConstraintSystemPhase CurrPhase;
 
     /// A map from each UnresolvedMemberExpr to the respective (implicit) base
     /// found during our walk.
@@ -1253,23 +1252,15 @@ namespace {
 
   public:
     ConstraintGenerator(ConstraintSystem &CS, DeclContext *DC)
-        : CS(CS), CurDC(DC ? DC : CS.DC), CurrPhase(CS.getPhase()) {
-      // Although constraint system is initialized in `constraint
-      // generation` phase, we have to set it here manually because e.g.
-      // result builders could generate constraints for its body
-      // in the middle of the solving.
-      CS.setPhase(ConstraintSystemPhase::ConstraintGeneration);
-
+        : CS(CS), CurDC(DC ? DC : CS.DC) {
       // Pick up the saved stack of pack expansions so we can continue
       // to handle pack element references inside the closure body.
       if (auto *ACE = dyn_cast<AbstractClosureExpr>(CurDC)) {
         OuterExpansions = CS.getCapturedExpansions(ACE);
       }
     }
 
-    virtual ~ConstraintGenerator() {
-      CS.setPhase(CurrPhase);
-    }
+    virtual ~ConstraintGenerator() = default;
 
     ConstraintSystem &getConstraintSystem() const { return CS; }
 

lib/Sema/CSSolver.cpp

@@ -1577,8 +1577,6 @@ bool ConstraintSystem::solve(SmallVectorImpl<Solution> &solutions,
 void ConstraintSystem::solveImpl(SmallVectorImpl<Solution> &solutions) {
   assert(solverState);
 
-  setPhase(ConstraintSystemPhase::Solving);
-
   // If constraint system failed while trying to
   // genenerate constraints, let's stop right here.
   if (failedConstraint)