‘explain_node’ may be used uninitialized in this function

[ 51%] Building CXX object sql/CMakeFiles/sql.dir/sql_select.cc.o

In file included from /home/svoj/devel/maria/10.0/sql/handler.h:34:0,

                 from /home/svoj/devel/maria/10.0/sql/datadict.h:18,

                 from /home/svoj/devel/maria/10.0/sql/table.h:23,

                 from /home/svoj/devel/maria/10.0/sql/field.h:29,

                 from /home/svoj/devel/maria/10.0/sql/unireg.h:172,

                 from /home/svoj/devel/maria/10.0/sql/sql_select.cc:33:

/home/svoj/devel/maria/10.0/sql/sql_array.h: In member function ‘int JOIN::save_explain_data_intern(Explain_query*, bool, bool, bool, const char*)’:

/home/svoj/devel/maria/10.0/sql/sql_array.h:159:38: warning: ‘explain_node’ may be used uninitialized in this function [-Wmaybe-uninitialized]

     return insert_dynamic(&array, &el);

                                      ^

/home/svoj/devel/maria/10.0/sql/sql_select.cc:23218:17: note: ‘explain_node’ was declared here

   Explain_node *explain_node;

                 ^