Initialize the Hash_set during creation

If the Hash_set is not initialized, one can not call find() on it before
at least one element has been inserted into it.

sql/sql_hset.h

@@ -28,17 +28,15 @@ class Hash_set
 public:
   enum { START_SIZE= 8 };
   /**
-    Constructs an empty hash. Does not allocate memory, it is done upon
-    the first insert. Thus does not cause or return errors.
+    Constructs an empty unique hash.
   */
   Hash_set(PSI_memory_key psi_key, uchar *(*K)(const T *, size_t *, my_bool),
            CHARSET_INFO *cs= &my_charset_bin)
   {
-    my_hash_clear(&m_hash);
-    m_hash.get_key= (my_hash_get_key)K;
-    m_hash.charset= cs;
-    m_hash.array.m_psi_key= psi_key;
+    my_hash_init(psi_key, &m_hash, cs, START_SIZE, 0, 0, (my_hash_get_key)K, 0,
+                 HASH_UNIQUE);
   }
+
   Hash_set(PSI_memory_key psi_key, CHARSET_INFO *charset, ulong default_array_elements,
            size_t key_offset, size_t key_length, my_hash_get_key get_key,
            void (*free_element)(void*), uint flags)
@@ -65,8 +63,6 @@ class Hash_set
   */
   bool insert(T *value)
   {
-    my_hash_init_opt(m_hash.array.m_psi_key, &m_hash, m_hash.charset,
-                     START_SIZE, 0, 0, m_hash.get_key, 0, HASH_UNIQUE);
     return my_hash_insert(&m_hash, reinterpret_cast<const uchar*>(value));
   }
   bool remove(T *value)