MDEV-31184 Remove parser tokens DECODE_MARIADB_SYM and DECODE_ORACLE_SYM

Changing the code handling sql_mode-dependent function DECODE():

- removing parser tokens DECODE_MARIADB_SYM and DECODE_ORACLE_SYM
- removing the DECODE() related code from sql_yacc.yy/sql_yacc_ora.yy
- adding handling of DECODE() with help of a new Create_func_func_decode

mysql-test/main/func_str.result

@@ -5270,5 +5270,17 @@ SELECT GROUP_CONCAT( UpdateXML( '<a>new year</a>', '/a', '2019-01-01 00:00:00' )
 f
 2019-01-01 00:00:00F}^i
 #
+# MDEV-31184 Remove parser tokens DECODE_MARIADB_SYM and DECODE_ORACLE_SYM
+#
+SELECT DECODE();
+ERROR 42000: Incorrect parameter count in the call to native function 'DECODE'
+SELECT DECODE(NULL);
+ERROR 42000: Incorrect parameter count in the call to native function 'DECODE'
+SELECT DECODE(NULL,NULL);
+DECODE(NULL,NULL)
+NULL
+SELECT DECODE(NULL, NULL, NULL);
+ERROR 42000: Incorrect parameter count in the call to native function 'DECODE'
+#
 # End of 10.4 tests
 #

mysql-test/main/func_str.test

@@ -2292,6 +2292,19 @@ DROP TABLE t1,t2;
 SELECT GROUP_CONCAT( UpdateXML( '<a>new year</a>', '/a', '2019-01-01 00:00:00' ), ENCODE('text','pass') ) AS f;
 
 
+--echo #
+--echo # MDEV-31184 Remove parser tokens DECODE_MARIADB_SYM and DECODE_ORACLE_SYM
+--echo #
+
+--error ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT
+SELECT DECODE();
+--error ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT
+SELECT DECODE(NULL);
+SELECT DECODE(NULL,NULL);
+--error ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT
+SELECT DECODE(NULL, NULL, NULL);
+
+
 --echo #
 --echo # End of 10.4 tests
 --echo #

mysql-test/suite/compat/oracle/r/func_decode.result

 SET sql_mode=ORACLE;
 SELECT DECODE(10);
-ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ')' at line 1
+ERROR 42000: Incorrect parameter count in the call to native function 'DECODE'
 SELECT DECODE(10,10);
-ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ')' at line 1
+ERROR 42000: Incorrect parameter count in the call to native function 'DECODE'
 SELECT DECODE(10,10,'x10');
 DECODE(10,10,'x10')
 x10
@@ -35,9 +35,9 @@ DROP TABLE decode;
 # MDEV-13863 sql_mode=ORACLE: DECODE does not treat two NULLs as equivalent
 #
 SELECT DECODE(10);
-ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ')' at line 1
+ERROR 42000: Incorrect parameter count in the call to native function 'DECODE'
 SELECT DECODE(10,10);
-ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ')' at line 1
+ERROR 42000: Incorrect parameter count in the call to native function 'DECODE'
 SELECT DECODE_ORACLE(10);
 ERROR 42000: Incorrect parameter count in the call to native function 'DECODE_ORACLE'
 SELECT DECODE_ORACLE(10,10);

mysql-test/suite/compat/oracle/t/func_decode.test

 SET sql_mode=ORACLE;
 
---error ER_PARSE_ERROR
+--error ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT
 SELECT DECODE(10);
---error ER_PARSE_ERROR
+--error ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT
 SELECT DECODE(10,10);
 
 SELECT DECODE(10,10,'x10');
@@ -25,9 +25,9 @@ DROP TABLE decode;
 --echo # MDEV-13863 sql_mode=ORACLE: DECODE does not treat two NULLs as equivalent
 --echo #
 
---error ER_PARSE_ERROR
+--error ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT
 SELECT DECODE(10);
---error ER_PARSE_ERROR
+--error ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT
 SELECT DECODE(10,10);
 
 --error ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT

sql/item_create.cc

@@ -602,7 +602,15 @@ class Create_func_decode_oracle : public Create_native_func
 {
 public:
   virtual Item *create_native(THD *thd, const LEX_CSTRING *name,
-                              List<Item> *item_list);
+                              List<Item> *item_list)
+  {
+    if (unlikely(!item_list || item_list->elements < 3))
+    {
+      my_error(ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT, MYF(0), name->str);
+      return NULL;
+    }
+    return new (thd->mem_root) Item_func_decode_oracle(thd, *item_list);
+  }
 
   static Create_func_decode_oracle s_singleton;
 
@@ -612,6 +620,33 @@ class Create_func_decode_oracle : public Create_native_func
 };
 
 
+class Create_func_decode : public Create_native_func
+{
+public:
+  virtual Item *create_native(THD *thd, const LEX_CSTRING *name,
+                              List<Item> *item_list)
+  {
+    if (thd->variables.sql_mode & MODE_ORACLE)
+      return Create_func_decode_oracle::s_singleton.create_native(thd, name,
+                                                                  item_list);
+    if (unlikely(!item_list || item_list->elements != 2))
+    {
+      my_error(ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT, MYF(0), name->str);
+      return NULL;
+    }
+    Item_args args(thd, *item_list);
+    return new (thd->mem_root) Item_func_decode(thd, args.arguments()[0],
+                                                     args.arguments()[1]);
+  }
+
+  static Create_func_decode s_singleton;
+
+protected:
+  Create_func_decode() {}
+  virtual ~Create_func_decode() {}
+};
+
+
 class Create_func_concat_ws : public Create_native_func
 {
 public:
@@ -4074,20 +4109,9 @@ Create_func_decode_histogram::create_2_arg(THD *thd, Item *arg1, Item *arg2)
   return new (thd->mem_root) Item_func_decode_histogram(thd, arg1, arg2);
 }
 
-Create_func_decode_oracle Create_func_decode_oracle::s_singleton;
+Create_func_decode Create_func_decode::s_singleton;
 
-Item*
-Create_func_decode_oracle::create_native(THD *thd, const LEX_CSTRING *name,
-                                         List<Item> *item_list)
-{
-  uint arg_count= item_list ? item_list->elements : 0;
-  if (unlikely(arg_count < 3))
-  {
-    my_error(ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT, MYF(0), name->str);
-    return NULL;
-  }
-  return new (thd->mem_root) Item_func_decode_oracle(thd, *item_list);
-}
+Create_func_decode_oracle Create_func_decode_oracle::s_singleton;
 
 Create_func_concat_ws Create_func_concat_ws::s_singleton;
 
@@ -7285,6 +7309,7 @@ const Native_func_registry func_array[] =
   { { STRING_WITH_LEN("DAYOFMONTH") }, BUILDER(Create_func_dayofmonth)},
   { { STRING_WITH_LEN("DAYOFWEEK") }, BUILDER(Create_func_dayofweek)},
   { { STRING_WITH_LEN("DAYOFYEAR") }, BUILDER(Create_func_dayofyear)},
+  { { STRING_WITH_LEN("DECODE") }, BUILDER(Create_func_decode)},
   { { STRING_WITH_LEN("DEGREES") }, BUILDER(Create_func_degrees)},
   { { STRING_WITH_LEN("DECODE_HISTOGRAM") }, BUILDER(Create_func_decode_histogram)},
   { { STRING_WITH_LEN("DECODE_ORACLE") }, BUILDER(Create_func_decode_oracle)},

sql/lex.h

@@ -744,7 +744,6 @@ SYMBOL sql_functions[] = {
   { "DATE_ADD",		SYM(DATE_ADD_INTERVAL)},
   { "DATE_SUB",		SYM(DATE_SUB_INTERVAL)},
   { "DATE_FORMAT",      SYM(DATE_FORMAT_SYM)},
-  { "DECODE",           SYM(DECODE_MARIADB_SYM)},
   { "DENSE_RANK",       SYM(DENSE_RANK_SYM)},
   { "EXTRACT",		SYM(EXTRACT_SYM)},
   { "FIRST_VALUE",      SYM(FIRST_VALUE_SYM)},

sql/sql_lex.cc

@@ -873,7 +873,6 @@ int Lex_input_stream::find_keyword(Lex_ident_cli_st *kwd,
       case CLOB_MARIADB_SYM:           return CLOB_ORACLE_SYM;
       case CONTINUE_MARIADB_SYM:       return CONTINUE_ORACLE_SYM;
       case DECLARE_MARIADB_SYM:        return DECLARE_ORACLE_SYM;
-      case DECODE_MARIADB_SYM:         return DECODE_ORACLE_SYM;
       case ELSEIF_MARIADB_SYM:         return ELSEIF_ORACLE_SYM;
       case ELSIF_MARIADB_SYM:          return ELSIF_ORACLE_SYM;
       case EXCEPTION_MARIADB_SYM:      return EXCEPTION_ORACLE_SYM;

sql/sql_yacc.yy

@@ -1275,8 +1275,6 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
 %token  <kwd>  DATE_SYM                      /* SQL-2003-R, Oracle-R, PLSQL-R */
 %token  <kwd>  DAY_SYM                       /* SQL-2003-R */
 %token  <kwd>  DEALLOCATE_SYM                /* SQL-2003-R */
-%token  <kwd>  DECODE_MARIADB_SYM            /* Function, non-reserved */
-%token  <kwd>  DECODE_ORACLE_SYM             /* Function, non-reserved */
 %token  <kwd>  DEFINER_SYM
 %token  <kwd>  DELAYED_SYM
 %token  <kwd>  DELAY_KEY_WRITE_SYM
@@ -1949,7 +1947,6 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
 %type <item_list>
         expr_list opt_udf_expr_list udf_expr_list when_list when_list_opt_else
         ident_list ident_list_arg opt_expr_list
-        decode_when_list_oracle
         execute_using
         execute_params
 
@@ -11027,18 +11024,6 @@ function_call_nonkeyword:
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | DECODE_MARIADB_SYM '(' expr ',' expr ')'
-          {
-            $$= new (thd->mem_root) Item_func_decode(thd, $3, $5);
-            if (unlikely($$ == NULL))
-              MYSQL_YYABORT;
-          }
-        | DECODE_ORACLE_SYM '(' expr ',' decode_when_list_oracle ')'
-          {
-            $5->push_front($3, thd->mem_root);
-            if (unlikely(!($$= new (thd->mem_root) Item_func_decode_oracle(thd, *$5))))
-              MYSQL_YYABORT;
-          }
         | EXTRACT_SYM '(' interval FROM expr ')'
           {
             $$=new (thd->mem_root) Item_extract(thd, $3, $5);
@@ -12209,25 +12194,6 @@ when_list_opt_else:
           }
         ;
 
-decode_when_list_oracle:
-          expr ',' expr
-          {
-            $$= new (thd->mem_root) List<Item>;
-            if (unlikely($$ == NULL) ||
-                unlikely($$->push_back($1, thd->mem_root)) ||
-                unlikely($$->push_back($3, thd->mem_root)))
-              MYSQL_YYABORT;
-
-          }
-        | decode_when_list_oracle ',' expr
-          {
-            $$= $1;
-            if (unlikely($$->push_back($3, thd->mem_root)))
-              MYSQL_YYABORT;
-          }
-        ;
-
-
 /* Equivalent to <table reference> in the SQL:2003 standard. */
 /* Warning - may return NULL in case of incomplete SELECT */
 table_ref:
@@ -16365,8 +16331,6 @@ keyword_sp_var_and_label:
         | DATAFILE_SYM
         | DATE_FORMAT_SYM
         | DAY_SYM
-        | DECODE_MARIADB_SYM
-        | DECODE_ORACLE_SYM
         | DEFINER_SYM
         | DELAY_KEY_WRITE_SYM
         | DES_KEY_FILE

sql/sql_yacc_ora.yy

@@ -751,8 +751,6 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
 %token  <kwd>  DATE_SYM                      /* SQL-2003-R, Oracle-R, PLSQL-R */
 %token  <kwd>  DAY_SYM                       /* SQL-2003-R */
 %token  <kwd>  DEALLOCATE_SYM                /* SQL-2003-R */
-%token  <kwd>  DECODE_MARIADB_SYM            /* Function, non-reserved */
-%token  <kwd>  DECODE_ORACLE_SYM             /* Function, non-reserved */
 %token  <kwd>  DEFINER_SYM
 %token  <kwd>  DELAYED_SYM
 %token  <kwd>  DELAY_KEY_WRITE_SYM
@@ -1432,7 +1430,6 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
 %type <item_list>
         expr_list opt_udf_expr_list udf_expr_list when_list when_list_opt_else
         ident_list ident_list_arg opt_expr_list
-        decode_when_list_oracle
         execute_using
         execute_params
 
@@ -11142,18 +11139,6 @@ function_call_nonkeyword:
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | DECODE_MARIADB_SYM '(' expr ',' expr ')'
-          {
-            $$= new (thd->mem_root) Item_func_decode(thd, $3, $5);
-            if (unlikely($$ == NULL))
-              MYSQL_YYABORT;
-          }
-        | DECODE_ORACLE_SYM '(' expr ',' decode_when_list_oracle ')'
-          {
-            $5->push_front($3, thd->mem_root);
-            if (unlikely(!($$= new (thd->mem_root) Item_func_decode_oracle(thd, *$5))))
-              MYSQL_YYABORT;
-          }
         | EXTRACT_SYM '(' interval FROM expr ')'
           {
             $$=new (thd->mem_root) Item_extract(thd, $3, $5);
@@ -12324,25 +12309,6 @@ when_list_opt_else:
           }
         ;
 
-decode_when_list_oracle:
-          expr ',' expr
-          {
-            $$= new (thd->mem_root) List<Item>;
-            if (unlikely($$ == NULL) ||
-                unlikely($$->push_back($1, thd->mem_root)) ||
-                unlikely($$->push_back($3, thd->mem_root)))
-              MYSQL_YYABORT;
-
-          }
-        | decode_when_list_oracle ',' expr
-          {
-            $$= $1;
-            if (unlikely($$->push_back($3, thd->mem_root)))
-              MYSQL_YYABORT;
-          }
-        ;
-
-
 /* Equivalent to <table reference> in the SQL:2003 standard. */
 /* Warning - may return NULL in case of incomplete SELECT */
 table_ref:
@@ -16535,8 +16501,6 @@ keyword_sp_var_and_label:
         | DATAFILE_SYM
         | DATE_FORMAT_SYM
         | DAY_SYM
-        | DECODE_MARIADB_SYM
-        | DECODE_ORACLE_SYM
         | DEFINER_SYM
         | DELAY_KEY_WRITE_SYM
         | DES_KEY_FILE