[MDEV-7978] Update grammar for new syntax

Extend the syntax accepted by the grammar to account for the new create user
and alter user syntax.

sql/mysqld.cc

@@ -3827,6 +3827,7 @@ SHOW_VAR com_status_vars[]= {
   {"alter_server",         STMT_STATUS(SQLCOM_ALTER_SERVER)},
   {"alter_table",          STMT_STATUS(SQLCOM_ALTER_TABLE)},
   {"alter_tablespace",     STMT_STATUS(SQLCOM_ALTER_TABLESPACE)},
+  {"alter_user",           STMT_STATUS(SQLCOM_ALTER_USER)},
   {"analyze",              STMT_STATUS(SQLCOM_ANALYZE)},
   {"assign_to_keycache",   STMT_STATUS(SQLCOM_ASSIGN_TO_KEYCACHE)},
   {"begin",                STMT_STATUS(SQLCOM_BEGIN)},

sql/sp_head.cc

@@ -283,6 +283,7 @@ sp_get_flags_for_command(LEX *lex)
   case SQLCOM_CREATE_USER:
   case SQLCOM_CREATE_ROLE:
   case SQLCOM_ALTER_TABLE:
+  case SQLCOM_ALTER_USER:
   case SQLCOM_GRANT:
   case SQLCOM_GRANT_ROLE:
   case SQLCOM_REVOKE:

sql/sql_acl.cc

@@ -9744,6 +9744,26 @@ bool mysql_rename_user(THD *thd, List <LEX_USER> &list)
   DBUG_RETURN(result);
 }
 
+/*
+  Alter a user's connection and resource settings.
+
+  SYNOPSIS
+    mysql_alter_user()
+    thd                         The current thread.
+    list                        The users to alter.
+
+  RETURN
+    > 0         Error. Error message already sent.
+    0           OK.
+    < 0         Error. Error message not yet sent.
+*/
+int mysql_alter_user(THD* thd, List<LEX_USER> &users_list)
+{
+  DBUG_ENTER("mysql_alter_user");
+  int result= 0;
+  // TODO implement the alter user logic.
+  DBUG_RETURN(result);
+}
 
 /*
   Revoke all privileges from a list of users.

sql/sql_acl.h

@@ -251,6 +251,7 @@ void get_mqh(const char *user, const char *host, USER_CONN *uc);
 bool mysql_create_user(THD *thd, List <LEX_USER> &list, bool handle_as_role);
 bool mysql_drop_user(THD *thd, List <LEX_USER> &list, bool handle_as_role);
 bool mysql_rename_user(THD *thd, List <LEX_USER> &list);
+int mysql_alter_user(THD *thd, List <LEX_USER> &list);
 bool mysql_revoke_all(THD *thd, List <LEX_USER> &list);
 void fill_effective_table_privileges(THD *thd, GRANT_INFO *grant,
                                      const char *db, const char *table);

sql/sql_cmd.h

@@ -93,6 +93,7 @@ enum enum_sql_command {
   SQLCOM_CREATE_ROLE, SQLCOM_DROP_ROLE, SQLCOM_GRANT_ROLE, SQLCOM_REVOKE_ROLE,
   SQLCOM_COMPOUND,
   SQLCOM_SHOW_GENERIC,
+  SQLCOM_ALTER_USER,
 
   /*
     When a command is added here, be sure it's also added in mysqld.cc

sql/sql_parse.cc

@@ -438,6 +438,7 @@ void init_update_queries(void)
   sql_command_flags[SQLCOM_CREATE_USER]=       CF_CHANGES_DATA;
   sql_command_flags[SQLCOM_RENAME_USER]=       CF_CHANGES_DATA;
   sql_command_flags[SQLCOM_DROP_USER]=         CF_CHANGES_DATA;
+  sql_command_flags[SQLCOM_ALTER_USER]=        CF_CHANGES_DATA;
   sql_command_flags[SQLCOM_CREATE_ROLE]=       CF_CHANGES_DATA;
   sql_command_flags[SQLCOM_GRANT]=             CF_CHANGES_DATA;
   sql_command_flags[SQLCOM_GRANT_ROLE]=        CF_CHANGES_DATA;
@@ -494,6 +495,7 @@ void init_update_queries(void)
   sql_command_flags[SQLCOM_CHECKSUM]=  CF_REPORT_PROGRESS;
 
   sql_command_flags[SQLCOM_CREATE_USER]|=       CF_AUTO_COMMIT_TRANS;
+  sql_command_flags[SQLCOM_ALTER_USER]|=        CF_AUTO_COMMIT_TRANS;
   sql_command_flags[SQLCOM_DROP_USER]|=         CF_AUTO_COMMIT_TRANS;
   sql_command_flags[SQLCOM_RENAME_USER]|=       CF_AUTO_COMMIT_TRANS;
   sql_command_flags[SQLCOM_CREATE_ROLE]|=       CF_AUTO_COMMIT_TRANS;
@@ -587,6 +589,7 @@ void init_update_queries(void)
   sql_command_flags[SQLCOM_ALTER_EVENT]|=      CF_DISALLOW_IN_RO_TRANS;
   sql_command_flags[SQLCOM_DROP_EVENT]|=       CF_DISALLOW_IN_RO_TRANS;
   sql_command_flags[SQLCOM_CREATE_USER]|=      CF_DISALLOW_IN_RO_TRANS;
+  sql_command_flags[SQLCOM_ALTER_USER]|=       CF_DISALLOW_IN_RO_TRANS;
   sql_command_flags[SQLCOM_RENAME_USER]|=      CF_DISALLOW_IN_RO_TRANS;
   sql_command_flags[SQLCOM_DROP_USER]|=        CF_DISALLOW_IN_RO_TRANS;
   sql_command_flags[SQLCOM_CREATE_SERVER]|=    CF_DISALLOW_IN_RO_TRANS;
@@ -4638,6 +4641,7 @@ mysql_execute_command(THD *thd)
       my_ok(thd);
     break;
   }
+  case SQLCOM_ALTER_USER:
   case SQLCOM_RENAME_USER:
   {
     if (check_access(thd, UPDATE_ACL, "mysql", NULL, NULL, 1, 1) &&
@@ -4645,7 +4649,11 @@ mysql_execute_command(THD *thd)
       break;
     /* Conditionally writes to binlog */
     WSREP_TO_ISOLATION_BEGIN(WSREP_MYSQL_DB, NULL, NULL)
-    if (!(res= mysql_rename_user(thd, lex->users_list)))
+    if (lex->sql_command == SQLCOM_ALTER_USER)
+      res= mysql_alter_user(thd, lex->users_list);
+    else
+      res= mysql_rename_user(thd, lex->users_list);
+    if (!res)
       my_ok(thd);
     break;
   }

sql/sql_yacc.yy

@@ -2575,6 +2575,7 @@ create:
           }
           view_or_trigger_or_sp_or_event { }
         | create_or_replace USER opt_if_not_exists clear_privileges grant_list
+          require_clause resource_options
           {
             if (Lex->set_command_with_check(SQLCOM_CREATE_USER, $1 | $3))
               MYSQL_YYABORT;
@@ -7341,6 +7342,11 @@ alter:
             lex->sql_command= SQLCOM_ALTER_SERVER;
             lex->server_options.reset($3);
           } OPTIONS_SYM '(' server_options_list ')' { }
+        | ALTER opt_if_exists USER clear_privileges user_list
+          require_clause resource_options
+          {
+            Lex->sql_command= SQLCOM_ALTER_USER;
+          }
         ;
 
 ev_alter_on_schedule_completion:
@@ -15741,24 +15747,8 @@ require_clause:
           }
         ;
 
-grant_options:
-          /* empty */ {}
-        | WITH grant_option_list
-        ;
-
-opt_grant_option:
-          /* empty */ {}
-        | WITH GRANT OPTION { Lex->grant |= GRANT_ACL;}
-        ;
-
-grant_option_list:
-          grant_option_list grant_option {}
-        | grant_option {}
-        ;
-
-grant_option:
-          GRANT OPTION { Lex->grant |= GRANT_ACL;}
-        | MAX_QUERIES_PER_HOUR ulong_num
+resource_option:
+        MAX_QUERIES_PER_HOUR ulong_num
           {
             LEX *lex=Lex;
             lex->mqh.questions=$2;
@@ -15790,6 +15780,37 @@ grant_option:
           }
         ;
 
+resource_option_list:
+	  resource_option_list resource_option {}
+	| resource_option {}
+        ;
+
+resource_options:
+	  /* empty */ {}
+	| WITH resource_option_list
+        ;
+
+
+grant_options:
+          /* empty */ {}
+        | WITH grant_option_list {}
+        ;
+
+opt_grant_option:
+          /* empty */ {}
+        | WITH GRANT OPTION { Lex->grant |= GRANT_ACL;}
+        ;
+
+grant_option_list:
+          grant_option_list grant_option {}
+        | grant_option {}
+        ;
+
+grant_option:
+          GRANT OPTION { Lex->grant |= GRANT_ACL;}
+	| resource_option {}
+        ;
+
 begin:
           BEGIN_SYM
           {