The second cleanup patch in scope of BUG#11986.

1. Introduce parse_sql() as a high-level replacement for MYSQLparse().
parse_sql() is responsible to switch and restore "parser context"
(THD::m_lip for now).

2. Fix typo in sp.cc: THD::spcont should be reset *before* calling
the parser.

sql/event_data_objects.cc

@@ -1875,11 +1875,9 @@ Event_job_data::execute(THD *thd, bool drop)
 
   {
     Lex_input_stream lip(thd, thd->query, thd->query_length);
-    thd->m_lip= &lip;
     lex_start(thd);
-    int err= MYSQLparse(thd);
 
-    if (err || thd->is_fatal_error)
+    if (parse_sql(thd, &lip))
     {
       sql_print_error("Event Scheduler: "
                       "%serror during compilation of %s.%s",

sql/mysql_priv.h

@@ -618,6 +618,8 @@ bool check_string_char_length(LEX_STRING *str, const char *err_msg,
                               uint max_char_length, CHARSET_INFO *cs,
                               bool no_error);
 
+bool parse_sql(THD *thd, class Lex_input_stream *lip);
+
 enum enum_mysql_completiontype {
   ROLLBACK_RELEASE=-2, ROLLBACK=1,  ROLLBACK_AND_CHAIN=7,
   COMMIT_RELEASE=-1,   COMMIT=0,    COMMIT_AND_CHAIN=6
@@ -1953,7 +1955,6 @@ void free_list(I_List <i_string_pair> *list);
 void free_list(I_List <i_string> *list);
 
 /* sql_yacc.cc */
-extern int MYSQLparse(void *thd);
 #ifndef DBUG_OFF
 extern void turn_parser_debug_on();
 #endif

sql/sp.cc

@@ -384,15 +384,13 @@ db_load_routine(THD *thd, int type, sp_name *name, sp_head **sphp,
   if ((ret= sp_use_new_db(thd, name->m_db, &old_db, 1, &dbchanged)))
     goto end;
 
+  thd->spcont= NULL;
+
   {
     Lex_input_stream lip(thd, defstr.c_ptr(), defstr.length());
-    thd->m_lip= &lip;
     lex_start(thd);
-    ret= MYSQLparse(thd);
-  }
 
-  thd->spcont= 0;
-  if (ret || thd->is_fatal_error || newlex.sphead == NULL)
+    if (parse_sql(thd, &lip) || newlex.sphead == NULL)
     {
       sp_head *sp= newlex.sphead;
 
@@ -410,6 +408,8 @@ db_load_routine(THD *thd, int type, sp_name *name, sp_head **sphp,
       (*sphp)->set_info(created, modified, &chistics, sql_mode);
       (*sphp)->optimize();
     }
+  }
+
 end:
   lex_end(thd->lex);
   thd->spcont= old_spcont;

sql/sql_class.cc

@@ -342,7 +342,8 @@ THD::THD()
    in_lock_tables(0),
    bootstrap(0),
    derived_tables_processing(FALSE),
-   spcont(NULL)
+   spcont(NULL),
+   m_lip(NULL)
 {
   ulong tmp;
 

sql/sql_parse.cc

@@ -5343,12 +5343,11 @@ void mysql_parse(THD *thd, const char *inBuf, uint length,
     sp_cache_flush_obsolete(&thd->sp_func_cache);
 
     Lex_input_stream lip(thd, inBuf, length);
-    thd->m_lip= &lip;
 
-    int err= MYSQLparse(thd);
+    bool err= parse_sql(thd, &lip);
     *found_semicolon= lip.found_semicolon;
 
-    if (!err && ! thd->is_fatal_error)
+    if (!err)
     {
 #ifndef NO_EMBEDDED_ACCESS_CHECKS
       if (mqh_used && thd->user_connect &&
@@ -5371,8 +5370,8 @@ void mysql_parse(THD *thd, const char *inBuf, uint length,
             PROCESSLIST.
             Note that we don't need LOCK_thread_count to modify query_length.
           */
-          if (lip.found_semicolon &&
-              (thd->query_length= (ulong)(lip.found_semicolon - thd->query)))
+          if (*found_semicolon &&
+              (thd->query_length= (ulong)(*found_semicolon - thd->query)))
             thd->query_length--;
           /* Actually execute the query */
 	  mysql_execute_command(thd);
@@ -5426,12 +5425,10 @@ bool mysql_test_parse_for_slave(THD *thd, char *inBuf, uint length)
   DBUG_ENTER("mysql_test_parse_for_slave");
 
   Lex_input_stream lip(thd, inBuf, length);
-  thd->m_lip= &lip;
   lex_start(thd);
   mysql_reset_thd_for_next_command(thd);
-  int err= MYSQLparse((void*) thd);
 
-  if (!err && ! thd->is_fatal_error &&
+  if (!parse_sql(thd, &lip) &&
       all_tables_not_ok(thd,(TABLE_LIST*) lex->select_lex.table_list.first))
     error= 1;                  /* Ignore question */
   thd->end_statement();
@@ -7123,3 +7120,34 @@ bool check_string_char_length(LEX_STRING *str, const char *err_msg,
     my_error(ER_WRONG_STRING_LENGTH, MYF(0), str->str, err_msg, max_char_length);
   return TRUE;
 }
+
+
+extern int MYSQLparse(void *thd); // from sql_yacc.cc
+
+
+/**
+  This is a wrapper of MYSQLparse(). All the code should call parse_sql()
+  instead of MYSQLparse().
+
+  @param thd Thread context.
+  @param lip Lexer context.
+
+  @return Error status.
+    @retval FALSE on success.
+    @retval TRUE on parsing error.
+*/
+
+bool parse_sql(THD *thd, Lex_input_stream *lip)
+{
+  bool err_status;
+
+  DBUG_ASSERT(thd->m_lip == NULL);
+
+  thd->m_lip= lip;
+
+  err_status= MYSQLparse(thd) != 0 || thd->is_fatal_error;
+
+  thd->m_lip= NULL;
+
+  return err_status;
+}

sql/sql_partition.cc

@@ -3696,7 +3696,6 @@ bool mysql_unpack_partition(THD *thd,
   thd->variables.character_set_client= system_charset_info;
 
   Lex_input_stream lip(thd, part_buf, part_info_len);
-  thd->m_lip= &lip;
 
   lex_start(thd);
   /*
@@ -3725,7 +3724,7 @@ bool mysql_unpack_partition(THD *thd,
   lex.part_info->part_state= part_state;
   lex.part_info->part_state_len= part_state_len;
   DBUG_PRINT("info", ("Parse: %s", part_buf));
-  if (MYSQLparse((void*)thd) || thd->is_fatal_error)
+  if (parse_sql(thd, &lip))
   {
     thd->free_items();
     goto end;

sql/sql_prepare.cc

@@ -2858,12 +2858,11 @@ bool Prepared_statement::prepare(const char *packet, uint packet_len)
 
   Lex_input_stream lip(thd, thd->query, thd->query_length);
   lip.stmt_prepare_mode= TRUE;
-  thd->m_lip= &lip;
   lex_start(thd);
-  int err= MYSQLparse((void *)thd);
 
-  error= err || thd->is_fatal_error ||
-      thd->net.report_error || init_param_array(this);
+  error= parse_sql(thd, &lip) ||
+         thd->net.report_error ||
+         init_param_array(this);
 
   /*
     While doing context analysis of the query (in check_prepared_statement)

sql/sql_trigger.cc

@@ -981,12 +981,10 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
         thd->variables.sql_mode= (ulong)*trg_sql_mode;
 
         Lex_input_stream lip(thd, trg_create_str->str, trg_create_str->length);
-        thd->m_lip= &lip;
         lex_start(thd);
         thd->spcont= 0;
-        int err= MYSQLparse((void *)thd);
 
-        if (err || thd->is_fatal_error)
+        if (parse_sql(thd, &lip))
         {
           /* Currently sphead is always deleted in case of a parse error */
           DBUG_ASSERT(lex.sphead == 0);

sql/sql_view.cc

@@ -893,7 +893,7 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
   LEX *old_lex, *lex;
   Query_arena *arena, backup;
   TABLE_LIST *top_view= table->top_table();
-  int res;
+  bool res;
   bool result, view_is_mergeable;
   TABLE_LIST *view_main_select_tables;
   DBUG_ENTER("mysql_make_view");
@@ -1005,7 +1005,6 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
 
   {
     Lex_input_stream lip(thd, table->query.str, table->query.length);
-    thd->m_lip= &lip;
     lex_start(thd);
     view_select= &lex->select_lex;
     view_select->select_number= ++thd->select_number;
@@ -1039,7 +1038,7 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
                                 MODE_IGNORE_SPACE | MODE_NO_BACKSLASH_ESCAPES);
     CHARSET_INFO *save_cs= thd->variables.character_set_client;
     thd->variables.character_set_client= system_charset_info;
-    res= MYSQLparse((void *)thd);
+    res= parse_sql(thd, &lip);
 
     if ((old_lex->sql_command == SQLCOM_SHOW_FIELDS) ||
         (old_lex->sql_command == SQLCOM_SHOW_CREATE))
@@ -1048,7 +1047,7 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
     thd->variables.character_set_client= save_cs;
     thd->variables.sql_mode= save_mode;
   }
-  if (!res && !thd->is_fatal_error)
+  if (!res)
   {
     TABLE_LIST *view_tables= lex->query_tables;
     TABLE_LIST *view_tables_tail= 0;