modernize: replace typedef with using, use = default for default members

src/lmptype.h

@@ -104,10 +104,10 @@ static constexpr uint32_t MEMCPYMASK = (static_cast<uint32_t>(1) << 31) - 1U;
 
 #ifdef LAMMPS_SMALLBIG
 
-typedef int smallint;
-typedef int imageint;
-typedef int tagint;
-typedef int64_t bigint;
+using smallint = int;
+using imageint = int;
+using tagint = int;
+using bigint = int64_t;
 
 #define MAXSMALLINT INT_MAX
 #define MAXTAGINT INT_MAX
@@ -139,10 +139,10 @@ typedef int64_t bigint;
 
 #ifdef LAMMPS_BIGBIG
 
-typedef int smallint;
-typedef int64_t imageint;
-typedef int64_t tagint;
-typedef int64_t bigint;
+using smallint = int;
+using imageint = int64_t;
+using tagint = int64_t;
+using bigint = int64_t;
 
 #define MAXSMALLINT INT_MAX
 #define MAXTAGINT INT64_MAX

src/pointers.h

@@ -92,9 +92,9 @@ class Pointers {
     atomKK(ptr->atomKK),
     memoryKK(ptr->memoryKK),
     python(ptr->python) {}
-  virtual ~Pointers() noexcept(false) {}
+  virtual ~Pointers() noexcept(false) = default;
 
-  // remove other default members
+  // remove other default members where possible
 
   Pointers() = delete;
   Pointers(const Pointers &) = default;