Remember first error in Dummy_error_handler

Use Dummy_error_handler in open_stat_tables() to ignore all errors
when opening statistics tables.

Author: montywi

sql/sql_base.h

@@ -658,7 +658,6 @@ class No_such_table_error_handler : public Internal_error_handler
     trapped and no other errors have been seen. FALSE otherwise.
   */
   bool safely_trapped_errors();
-  bool any_error() { return m_handled_errors == 0 || m_unhandled_errors == 0; }
   uint got_error() { return first_error; }
 
 private:

sql/sql_class.h

@@ -1989,25 +1989,33 @@ class Internal_error_handler
 /**
   Implements the trivial error handler which cancels all error states
   and prevents an SQLSTATE to be set.
+  Remembers the first error
 */
 
 class Dummy_error_handler : public Internal_error_handler
 {
+  uint m_unhandled_errors;
+  uint first_error;
 public:
+  Dummy_error_handler()
+    : m_unhandled_errors(0), first_error(0)
+  {}
   bool handle_condition(THD *thd,
                         uint sql_errno,
                         const char* sqlstate,
                         Sql_condition::enum_warning_level *level,
                         const char* msg,
                         Sql_condition ** cond_hdl)
   {
-    /* Ignore error */
-    return TRUE;
+    m_unhandled_errors++;
+    if (!first_error)
+      first_error= sql_errno;
+    return TRUE;                                // Ignore error
   }
-  Dummy_error_handler() = default;                    /* Remove gcc warning */
+  bool any_error() { return m_unhandled_errors != 0; }
+  uint got_error() { return first_error; }
 };
 
-
 /**
   Implements the trivial error handler which counts errors as they happen.
 */

sql/sql_statistics.cc

@@ -293,17 +293,17 @@ static inline int open_stat_table_for_ddl(THD *thd, TABLE_LIST *table,
                                           const LEX_CSTRING *stat_tab_name)
 {
   table->init_one_table(&MYSQL_SCHEMA_NAME, stat_tab_name, NULL, TL_WRITE);
-  No_such_table_error_handler nst_handler;
-  thd->push_internal_handler(&nst_handler);
+  Dummy_error_handler error_handler;
+  thd->push_internal_handler(&error_handler);
   int res= open_system_tables_for_read(thd, table);
   thd->pop_internal_handler();
-  if (res && nst_handler.any_error())
+  if (res && error_handler.any_error())
   {
     push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
                         ER_CHECK_NO_SUCH_TABLE,
                         "Got error %d when trying to open statistics "
                         "table %`s for updating statistics",
-                        nst_handler.got_error(), stat_table_name->str);
+                        error_handler.got_error(), stat_table_name->str);
   }
   return res;
 }