diff --git a/extra/mariabackup/backup_mysql.cc b/extra/mariabackup/backup_mysql.cc
index bedb8ffb2ec..fee3b141206 100644
--- a/extra/mariabackup/backup_mysql.cc
+++ b/extra/mariabackup/backup_mysql.cc
@@ -334,7 +334,6 @@ get_mysql_vars(MYSQL *connection)
 	char *version_comment_var = NULL;
 	char *innodb_version_var = NULL;
 	char *have_backup_locks_var = NULL;
-	char *have_backup_safe_binlog_info_var = NULL;
 	char *log_bin_var = NULL;
 	char *lock_wait_timeout_var= NULL;
 	char *wsrep_on_var = NULL;
diff --git a/extra/mariabackup/xtrabackup.cc b/extra/mariabackup/xtrabackup.cc
index 7f3a04ff7ea..2af8c22533f 100644
--- a/extra/mariabackup/xtrabackup.cc
+++ b/extra/mariabackup/xtrabackup.cc
@@ -2014,7 +2014,6 @@ xtrabackup_read_metadata(char *filename)
 {
 	FILE	*fp;
 	my_bool	 r = TRUE;
-	int	 t;
 
 	fp = fopen(filename,"r");
 	if(!fp) {
@@ -5319,27 +5318,6 @@ innodb_free_param()
 }
 
 
-/** Store the current binary log coordinates in a specified file.
-@param[in]	filename	file name
-@param[in]	name		binary log file name
-@param[in]	pos		binary log file position
-@return whether the operation succeeded */
-static bool
-store_binlog_info(const char* filename, const char* name, ulonglong pos)
-{
-	FILE *fp = fopen(filename, "w");
-
-	if (!fp) {
-		msg("mariabackup: failed to open '%s'", filename);
-		return(false);
-	}
-
-	fprintf(fp, "%s\t%llu\n", name, pos);
-	fclose(fp);
-
-	return(true);
-}
-
 /** Check if file exists*/
 static bool file_exists(std::string name)
 {
diff --git a/sql/item_jsonfunc.cc b/sql/item_jsonfunc.cc
index 78eb58506ff..e236010c459 100644
--- a/sql/item_jsonfunc.cc
+++ b/sql/item_jsonfunc.cc
@@ -680,11 +680,11 @@ static int alloc_tmp_paths(THD *thd, uint n_paths,
 
       *paths= (json_path_with_flags *) alloc_root(root,
           sizeof(json_path_with_flags) * n_paths);
-      *tmp_paths= (String *) alloc_root(root, sizeof(String) * n_paths);
+
+      *tmp_paths= new (root) String[n_paths];
       if (*paths == 0 || *tmp_paths == 0)
         return 1;
 
-      bzero(*tmp_paths, sizeof(String) * n_paths);
       for (uint c_path=0; c_path < n_paths; c_path++)
         (*tmp_paths)[c_path].set_charset(&my_charset_utf8_general_ci);
     }
diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index da5e9707595..d7bbdeb82a4 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -1348,7 +1348,6 @@ QUICK_INDEX_SORT_SELECT::QUICK_INDEX_SORT_SELECT(THD *thd_param, TABLE *table)
   DBUG_ENTER("QUICK_INDEX_SORT_SELECT::QUICK_INDEX_SORT_SELECT");
   index= MAX_KEY;
   head= table;
-  bzero(&read_record, sizeof(read_record));
   init_sql_alloc(&alloc, thd->variables.range_alloc_block_size, 0,
                  MYF(MY_THREAD_SPECIFIC));
   DBUG_VOID_RETURN;
diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index 1d1cca0568e..ae6030115fa 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -772,7 +772,7 @@ enum enum_acl_tables
   ROLES_MAPPING_TABLE,
   TABLES_MAX // <== always the last
 };
-// bits for open_grant_tables
+
 static const int Table_user= 1 << USER_TABLE;
 static const int Table_db= 1 << DB_TABLE;
 static const int Table_tables_priv= 1 << TABLES_PRIV_TABLE;
@@ -853,7 +853,7 @@ class Grant_table_base
 
   Grant_table_base() : start_privilege_column(0), num_privilege_cols(0)
   {
-    bzero(&tl, sizeof(tl));
+    tl.reset();
   };
 
   /* Initialization sequence common for all grant tables. This should be called
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 69aa8a97a87..1dfd6520e17 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -2447,7 +2447,7 @@ bool JOIN::make_aggr_tables_info()
 
         aggr_tables++;
         curr_tab= join_tab + exec_join_tab_cnt();
-        bzero(curr_tab, sizeof(JOIN_TAB));
+        bzero((void*)curr_tab, sizeof(JOIN_TAB));
         curr_tab->ref.key= -1;
         curr_tab->join= this;
 
@@ -2535,7 +2535,7 @@ bool JOIN::make_aggr_tables_info()
   {
     aggr_tables++;
     curr_tab= join_tab + exec_join_tab_cnt();
-    bzero(curr_tab, sizeof(JOIN_TAB));
+    bzero((void*)curr_tab, sizeof(JOIN_TAB));
     curr_tab->ref.key= -1;
     if (only_const_tables())
       first_select= sub_select_postjoin_aggr;
@@ -2663,7 +2663,7 @@ bool JOIN::make_aggr_tables_info()
       
       curr_tab++;
       aggr_tables++;
-      bzero(curr_tab, sizeof(JOIN_TAB));
+      bzero((void*)curr_tab, sizeof(JOIN_TAB));
       curr_tab->ref.key= -1;
 
       /* group data to new table */
@@ -17448,7 +17448,7 @@ bool Virtual_tmp_table::init(uint field_count)
                         &bitmaps, bitmap_buffer_size(field_count) * 6,
                         NullS))
     return true;
-  bzero(s, sizeof(*s));
+  s->reset();
   s->blob_field= blob_field;
   setup_tmp_table_column_bitmaps(this, bitmaps, field_count);
   m_alloced_field_count= field_count;
diff --git a/sql/sql_select.h b/sql/sql_select.h
index 09e8f5a3e10..5eea5937ea6 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -2046,9 +2046,9 @@ public:
   static void *operator new(size_t size, THD *thd) throw();
   static void operator delete(void *ptr, size_t size) {TRASH_FREE(ptr, size);}
 
-  Virtual_tmp_table(THD *thd)
+  Virtual_tmp_table(THD *thd) : m_alloced_field_count(0)
   {
-    bzero(this, sizeof(*this));
+    reset();
     temp_pool_slot= MY_BIT_NONE;
     in_use= thd;
   }
diff --git a/sql/sql_string.h b/sql/sql_string.h
index ea810f15f80..0065b1424ce 100644
--- a/sql/sql_string.h
+++ b/sql/sql_string.h
@@ -27,6 +27,7 @@
 #include "m_ctype.h"                            /* my_charset_bin */
 #include "my_sys.h"              /* alloc_root, my_free, my_realloc */
 #include "m_string.h"                           /* TRASH */
+#include "sql_list.h"
 
 class String;
 typedef struct st_io_cache IO_CACHE;
@@ -129,7 +130,7 @@ uint convert_to_printable(char *to, size_t to_len,
                           const char *from, size_t from_len,
                           CHARSET_INFO *from_cs, size_t nbytes= 0);
 
-class String
+class String : public Sql_alloc
 {
   char *Ptr;
   uint32 str_length,Alloced_length, extra_alloc;
@@ -179,16 +180,6 @@ public:
     alloced= thread_specific= 0;
     str_charset=str.str_charset;
   }
-  static void *operator new(size_t size, MEM_ROOT *mem_root) throw ()
-  { return (void*) alloc_root(mem_root, (uint) size); }
-  static void operator delete(void *ptr_arg, size_t size)
-  {
-    (void) ptr_arg;
-    (void) size;
-    TRASH_FREE(ptr_arg, size);
-  }
-  static void operator delete(void *, MEM_ROOT *)
-  { /* never called */ }
   ~String() { free(); }
 
   /* Mark variable thread specific it it's not allocated already */
diff --git a/storage/innobase/os/os0file.cc b/storage/innobase/os/os0file.cc
index bfebc2e1b12..bb6a06240af 100644
--- a/storage/innobase/os/os0file.cc
+++ b/storage/innobase/os/os0file.cc
@@ -5782,7 +5782,7 @@ AIO::AIO(
 	m_not_full = os_event_create("aio_not_full");
 	m_is_empty = os_event_create("aio_is_empty");
 
-	memset(&m_slots[0], 0x0, sizeof(m_slots[0]) * m_slots.size());
+	memset((void*)&m_slots[0], 0x0, sizeof(m_slots[0]) * m_slots.size());
 #ifdef LINUX_NATIVE_AIO
 	memset(&m_events[0], 0x0, sizeof(m_events[0]) * m_events.size());
 #endif /* LINUX_NATIVE_AIO */
diff --git a/storage/mroonga/ha_mroonga.cpp b/storage/mroonga/ha_mroonga.cpp
index 46077a2671e..0c59398b90b 100644
--- a/storage/mroonga/ha_mroonga.cpp
+++ b/storage/mroonga/ha_mroonga.cpp
@@ -2591,7 +2591,7 @@ ha_mroonga::~ha_mroonga()
   }
   if (blob_buffers)
   {
-    ::delete [] blob_buffers;
+    delete [] blob_buffers;
   }
   grn_obj_unlink(ctx, &top_left_point);
   grn_obj_unlink(ctx, &bottom_right_point);
@@ -4726,11 +4726,8 @@ int ha_mroonga::storage_open_columns(void)
 
   if (table_share->blob_fields)
   {
-    if (blob_buffers)
-    {
-      delete [] blob_buffers;
-    }
-    if (!(blob_buffers = new String[n_columns]))
+    DBUG_ASSERT(!blob_buffers);
+    if (!(blob_buffers = new (&table->mem_root) String[n_columns]))
     {
       DBUG_RETURN(HA_ERR_OUT_OF_MEM);
     }
diff --git a/storage/rocksdb/ha_rocksdb.cc b/storage/rocksdb/ha_rocksdb.cc
index 768c967ef63..6ce00cb4d1c 100644
--- a/storage/rocksdb/ha_rocksdb.cc
+++ b/storage/rocksdb/ha_rocksdb.cc
@@ -676,7 +676,7 @@ static void rocksdb_set_rocksdb_info_log_level(
   RDB_MUTEX_LOCK_CHECK(rdb_sysvars_mutex);
   rocksdb_info_log_level = *static_cast<const uint64_t *>(save);
   rocksdb_db_options->info_log->SetInfoLogLevel(
-      static_cast<const rocksdb::InfoLogLevel>(rocksdb_info_log_level));
+      static_cast<rocksdb::InfoLogLevel>(rocksdb_info_log_level));
   RDB_MUTEX_UNLOCK_CHECK(rdb_sysvars_mutex);
 }
 
diff --git a/storage/rocksdb/rdb_datadic.cc b/storage/rocksdb/rdb_datadic.cc
index 4ca37897edd..8e286547940 100644
--- a/storage/rocksdb/rdb_datadic.cc
+++ b/storage/rocksdb/rdb_datadic.cc
@@ -127,9 +127,9 @@ Rdb_key_def::Rdb_key_def(const Rdb_key_def &k)
                   m_total_index_flags_length == 0);
   if (k.m_pack_info) {
     const size_t size = sizeof(Rdb_field_packing) * k.m_key_parts;
-    m_pack_info =
-        reinterpret_cast<Rdb_field_packing *>(my_malloc(size, MYF(0)));
-    memcpy(m_pack_info, k.m_pack_info, size);
+    void *pack_info= my_malloc(size, MYF(0));
+    memcpy(pack_info, k.m_pack_info, size);
+    m_pack_info = reinterpret_cast<Rdb_field_packing *>(pack_info);
   }
 
   if (k.m_pk_part_no) {
@@ -1090,7 +1090,7 @@ uint Rdb_key_def::pack_record(
       // Insert TTL timestamp
       if (has_ttl() && ttl_bytes) {
         write_index_flag_field(unpack_info,
-                               reinterpret_cast<const uchar *const>(ttl_bytes),
+                               reinterpret_cast<const uchar *>(ttl_bytes),
                                Rdb_key_def::TTL_FLAG);
       }
     }
diff --git a/storage/rocksdb/rdb_threads.cc b/storage/rocksdb/rdb_threads.cc
index 276f228d7cc..2214ce1a043 100644
--- a/storage/rocksdb/rdb_threads.cc
+++ b/storage/rocksdb/rdb_threads.cc
@@ -28,7 +28,7 @@ namespace myrocks {
 
 void *Rdb_thread::thread_func(void *const thread_ptr) {
   DBUG_ASSERT(thread_ptr != nullptr);
-  Rdb_thread *const thread = static_cast<Rdb_thread *const>(thread_ptr);
+  Rdb_thread *const thread = static_cast<Rdb_thread *>(thread_ptr);
   if (!thread->m_run_once.exchange(true)) {
     thread->setname();
     thread->run();