[CSOptimizer] NFC: Switch to llvm::Optional

Author: xedin

include/swift/Sema/ConstraintSystem.h

@@ -5214,7 +5214,7 @@ class ConstraintSystem {
   /// Pick a disjunction from the InactiveConstraints list.
   ///
   /// \returns The selected disjunction and a set of it's favored choices.
-  Optional<std::pair<Constraint *, llvm::TinyPtrVector<Constraint *>>>
+  llvm::Optional<std::pair<Constraint *, llvm::TinyPtrVector<Constraint *>>>
   selectDisjunction();
 
   /// Pick a conjunction from the InactiveConstraints list.

lib/Sema/CSOptimizer.cpp

@@ -170,9 +170,8 @@ static void determineBestChoicesInContext(
     }
 
     // Match arguments to the given overload choice.
-    auto matchArguments =
-        [&](OverloadChoice choice,
-            FunctionType *overloadType) -> Optional<MatchCallArgumentResult> {
+    auto matchArguments = [&](OverloadChoice choice, FunctionType *overloadType)
+        -> llvm::Optional<MatchCallArgumentResult> {
       auto *decl = choice.getDeclOrNull();
       assert(decl);
 
@@ -187,7 +186,7 @@ static void determineBestChoicesInContext(
       return matchCallArguments(argsWithLabels, overloadType->getParams(),
                                 paramListInfo,
                                 argumentList->getFirstTrailingClosureIndex(),
-                                /*allow fixes*/ false, listener, None);
+                                /*allow fixes*/ false, listener, llvm::None);
     };
 
     // Determine whether the candidate type is a subclass of the superclass
@@ -634,13 +633,13 @@ selectBestBindingDisjunction(ConstraintSystem &cs,
   return firstBindDisjunction;
 }
 
-Optional<std::pair<Constraint *, llvm::TinyPtrVector<Constraint *>>>
+llvm::Optional<std::pair<Constraint *, llvm::TinyPtrVector<Constraint *>>>
 ConstraintSystem::selectDisjunction() {
   SmallVector<Constraint *, 4> disjunctions;
 
   collectDisjunctions(disjunctions);
   if (disjunctions.empty())
-    return None;
+    return llvm::None;
 
   if (auto *disjunction = selectBestBindingDisjunction(*this, disjunctions))
     return std::make_pair(disjunction, llvm::TinyPtrVector<Constraint *>());
@@ -678,5 +677,5 @@ ConstraintSystem::selectDisjunction() {
   if (bestDisjunction != disjunctions.end())
     return std::make_pair(*bestDisjunction, favorings[*bestDisjunction]);
 
-  return None;
+  return llvm::None;
 }