Switch from `typedef` to `using` in C++ code. NFC (#5258)

This is more modern and (IMHO) easier to read than that old C typedef
syntax.

3 files changed, 8 insertions, 8 deletions

diff --git a/src/support/insert_ordered.h b/src/support/insert_ordered.h
index 6b0f54968..1460c4329 100644
--- a/src/support/insert_ordered.h
+++ b/src/support/insert_ordered.h
@@ -32,7 +32,7 @@ template<typename T> struct InsertOrderedSet {
   std::unordered_map<T, typename std::list<T>::iterator> Map;
   std::list<T> List;
 
-  typedef typename std::list<T>::iterator iterator;
+  using iterator = typename std::list<T>::iterator;
   iterator begin() { return List.begin(); }
   iterator end() { return List.end(); }
 
@@ -87,7 +87,7 @@ template<typename Key, typename T> struct InsertOrderedMap {
     Map;
   std::list<std::pair<const Key, T>> List;
 
-  typedef typename std::list<std::pair<const Key, T>>::iterator iterator;
+  using iterator = typename std::list<std::pair<const Key, T>>::iterator;
   iterator begin() { return List.begin(); }
   iterator end() { return List.end(); }
 
diff --git a/src/support/json.h b/src/support/json.h
index 269b6c0e9..bc880f382 100644
--- a/src/support/json.h
+++ b/src/support/json.h
@@ -65,8 +65,8 @@ struct Value {
 
   Type type = Null;
 
-  typedef std::vector<Ref> ArrayStorage;
-  typedef std::unordered_map<IString, Ref> ObjectStorage;
+  using ArrayStorage = std::vector<Ref>;
+  using ObjectStorage = std::unordered_map<IString, Ref>;
 
   // MSVC does not allow unrestricted unions:
   // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2544.pdf
@@ -403,7 +403,7 @@ struct Value {
   }
 };
 
-typedef Value::Ref Ref;
+using Ref = Value::Ref;
 
 } // namespace json
 
diff --git a/src/support/small_vector.h b/src/support/small_vector.h
index 7c03ae02b..c798dc594 100644
--- a/src/support/small_vector.h
+++ b/src/support/small_vector.h
@@ -148,9 +148,9 @@ public:
   // iteration
 
   template<typename Parent, typename Iterator> struct IteratorBase {
-    typedef T value_type;
-    typedef long difference_type;
-    typedef T& reference;
+    using value_type = T;
+    using difference_type = long;
+    using reference = T&;
 
     Parent* parent;
     size_t index;