[Constraint solver] Eliminate addConstraint(Constraint*).

We no longer build constraints just to immediately simplify them.

Author: DougGregor

lib/Sema/ConstraintSystem.cpp

@@ -333,37 +333,6 @@ ConstraintLocator *ConstraintSystem::getConstraintLocator(
   return getConstraintLocator(anchor, path, builder.getSummaryFlags());
 }
 
-bool ConstraintSystem::addConstraint(Constraint *constraint) {
-  switch (simplifyConstraint(*constraint)) {
-  case SolutionKind::Error:
-    if (!failedConstraint) {
-      failedConstraint = constraint;
-    }
-
-    if (solverState) {
-      solverState->retiredConstraints.push_front(constraint);
-      solverState->generatedConstraints.push_back(constraint);
-    }
-
-    return false;
-
-  case SolutionKind::Solved:
-    // This constraint has already been solved; there is nothing more
-    // to do.
-    // Record solved constraint.
-    if (solverState) {
-      solverState->retiredConstraints.push_front(constraint);
-      solverState->generatedConstraints.push_back(constraint);
-    }
-
-    return true;
-
-  case SolutionKind::Unsolved:
-    addUnsolvedConstraint(constraint);
-    return false;
-  }
-}
-
 TypeVariableType *
 ConstraintSystem::getMemberType(TypeVariableType *baseTypeVar, 
                                 AssociatedTypeDecl *assocType,

lib/Sema/ConstraintSystem.h

@@ -1373,12 +1373,6 @@ class ConstraintSystem {
   /// emits an error message.
   void diagnoseFailureForExpr(Expr *expr);
 
-  /// \brief Add a newly-allocated constraint after attempting to simplify
-  /// it.
-  ///
-  /// \returns true if this constraint was solved.
-  bool addConstraint(Constraint *constraint);
-
   /// \brief Add a constraint to the constraint system.
   void addConstraint(ConstraintKind kind, Type first, Type second,
                      ConstraintLocatorBuilder locator,