[gardening][Driver] Replace typedef with using

include/swift/Driver/Action.h

@@ -34,9 +34,9 @@ namespace driver {
 
 class Action {
 public:
-  typedef ArrayRef<const Action *>::size_type size_type;
-  typedef ArrayRef<const Action *>::iterator iterator;
-  typedef ArrayRef<const Action *>::const_iterator const_iterator;
+  using size_type = ArrayRef<const Action *>::size_type;
+  using iterator = ArrayRef<const Action *>::iterator;
+  using const_iterator = ArrayRef<const Action *>::const_iterator;
 
   enum ActionClass {
     Input = 0,

include/swift/Driver/DependencyGraph.h

@@ -140,11 +140,11 @@ class DependencyGraphImpl {
   class StringSetIterator {
     llvm::StringSet<>::const_iterator I;
   public:
-    typedef llvm::StringSet<>::const_iterator::value_type value_type;
-    typedef std::input_iterator_tag iterator_category;
-    typedef ptrdiff_t difference_type;
-    typedef value_type &reference;
-    typedef value_type *pointer;
+    using value_type = llvm::StringSet<>::const_iterator::value_type;
+    using iterator_category = std::input_iterator_tag;
+    using difference_type = ptrdiff_t;
+    using reference = value_type &;
+    using pointer = value_type *;
 
     /*implicit*/ StringSetIterator(llvm::StringSet<>::const_iterator base)
        : I(base) {}

include/swift/Driver/Util.h

@@ -27,9 +27,9 @@ namespace swift {
 
 namespace driver {
   /// An input argument from the command line and its inferred type.
-  typedef std::pair<file_types::ID, const llvm::opt::Arg *> InputPair;
+  using InputPair = std::pair<file_types::ID, const llvm::opt::Arg *>;
   /// Type used for a list of input arguments.
-  typedef SmallVector<InputPair, 16> InputFileList;
+  using InputFileList = SmallVector<InputPair, 16>;
 
   enum class LinkKind {
     None,

lib/Driver/Driver.cpp

@@ -776,8 +776,7 @@ static Arg *makeInputArg(const DerivedArgList &Args, OptTable &Opts,
   return A;
 }
 
-
-typedef std::function<void(InputArgList &, unsigned)> RemainingArgsHandler;
+using RemainingArgsHandler = std::function<void(InputArgList &, unsigned)>;
 
 std::unique_ptr<InputArgList>
 parseArgsUntil(const llvm::opt::OptTable& Opts,

lib/Driver/ParseableOutput.cpp

@@ -30,7 +30,7 @@ namespace {
     CommandInput(StringRef Path) : Path(Path) {}
   };
 
-  typedef std::pair<file_types::ID, std::string> OutputPair;
+  using OutputPair = std::pair<file_types::ID, std::string>;
 } // end anonymous namespace
 
 namespace swift {