Backport of Bug#33204 from mysql-pe to

mysql-next-mr-bugfixing.

Bug no 32858 was fixed in two different ways in what was
then called mysql 5.1 and 6.0. The fix in 6.0 was very
different since bugfix no 33204 was present.  Furthermore,
the two fixes were not compatible. Hence in order to
backport Bug#33204 to the 5.1-based mysql-next-mr-bugfixing,
it was necessary to remove the 5.1 fix of 32858 and apply
the 6.0 version of the fix.


mysql-test/r/subselect.result:
  Bug#33204-backport: Test result
mysql-test/r/union.result:
  
  Bug#33204-backport:
  - Reversal of test result: bugfix no 32858 for 5.1
  - Application of test result: bugfix no 32858 for 6.0
mysql-test/t/subselect.test:
  Bug#33204-backport: 
  - Changed tests
  - Test case
mysql-test/t/union.test:
  Bug#33204-backport:
  - Reversal of test: bugfix no 32858 for 5.1
  - Application of test: bugfix no 32858 for 6.0
sql/sql_class.cc:
  Bug#33204-backport: Reversal of bugfix no 32858 for 5.1
sql/sql_class.h:
  Bug#33204-backport: Reversal of bugfix no 32858 for 5.1
sql/sql_yacc.yy:
  Bug#33204-backport:
  - Reversal of bugfix no 32858 for 5.1
  - Application of bugfix no 32858 for 6.0
  - Application of bugfix no 33204

3 files changed, 224 insertions, 114 deletions

diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index 757f6abb00b..95bdbc5e093 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -1626,7 +1626,6 @@ void THD::rollback_item_tree_changes()
 select_result::select_result()
 {
   thd=current_thd;
-  nest_level= -1;
 }
 
 void select_result::send_error(uint errcode,const char *err)
diff --git a/sql/sql_class.h b/sql/sql_class.h
index aaa959feae9..cefa65925d2 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -2381,7 +2381,6 @@ class select_result :public Sql_alloc {
 protected:
   THD *thd;
   SELECT_LEX_UNIT *unit;
-  uint nest_level;
 public:
   select_result();
   virtual ~select_result() {};
@@ -2418,12 +2417,6 @@ public:
   */
   virtual void cleanup();
   void set_thd(THD *thd_arg) { thd= thd_arg; }
-  /**
-     The nest level, if supported. 
-     @return
-     -1 if nest level is undefined, otherwise a positive integer.
-   */
-  int get_nest_level() { return nest_level; }
 #ifdef EMBEDDED_LIBRARY
   virtual void begin_dataset() {}
 #else
@@ -2518,14 +2511,6 @@ class select_export :public select_to_file {
   CHARSET_INFO *write_cs; // output charset
 public:
   select_export(sql_exchange *ex) :select_to_file(ex) {}
-  /**
-     Creates a select_export to represent INTO OUTFILE <filename> with a
-     defined level of subquery nesting.
-   */
-  select_export(sql_exchange *ex, uint nest_level_arg) :select_to_file(ex) 
-  {
-    nest_level= nest_level_arg;
-  }
   ~select_export();
   int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
   bool send_data(List<Item> &items);
@@ -2535,15 +2520,6 @@ public:
 class select_dump :public select_to_file {
 public:
   select_dump(sql_exchange *ex) :select_to_file(ex) {}
-  /**
-     Creates a select_export to represent INTO DUMPFILE <filename> with a
-     defined level of subquery nesting.
-   */  
-  select_dump(sql_exchange *ex, uint nest_level_arg) : 
-    select_to_file(ex) 
-  {
-    nest_level= nest_level_arg;
-  }
   int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
   bool send_data(List<Item> &items);
 };
@@ -3014,16 +2990,6 @@ class select_dumpvar :public select_result_interceptor {
 public:
   List<my_var> var_list;
   select_dumpvar()  { var_list.empty(); row_count= 0;}
-  /**
-     Creates a select_dumpvar to represent INTO <variable> with a defined 
-     level of subquery nesting.
-   */
-  select_dumpvar(uint nest_level_arg)
-  {
-    var_list.empty();
-    row_count= 0;
-    nest_level= nest_level_arg;
-  }
   ~select_dumpvar() {}
   int prepare(List<Item> &list, SELECT_LEX_UNIT *u);
   bool send_data(List<Item> &items);
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 05283718162..43f5c73f5e7 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -468,6 +468,90 @@ Item* handle_sql2003_note184_exception(THD *thd, Item* left, bool equal,
   DBUG_RETURN(result);
 }
 
+/**
+   @brief Creates a new SELECT_LEX for a UNION branch.
+
+   Sets up and initializes a SELECT_LEX structure for a query once the parser
+   discovers a UNION token. The current SELECT_LEX is pushed on the stack and
+   the new SELECT_LEX becomes the current one.
+
+   @param lex The parser state.
+
+   @param is_union_distinct True if the union preceding the new select statement
+   uses UNION DISTINCT.
+
+   @param is_top_level This should be @c TRUE if the newly created SELECT_LEX
+   is a non-nested statement.
+
+   @return <code>false</code> if successful, <code>true</code> if an error was
+   reported. In the latter case parsing should stop.
+ */
+bool add_select_to_union_list(LEX *lex, bool is_union_distinct, 
+                              bool is_top_level)
+{
+  /* 
+     Only the last SELECT can have INTO. Since the grammar won't allow INTO in
+     a nested SELECT, we make this check only when creating a top-level SELECT.
+  */
+  if (is_top_level && lex->result)
+  {
+    my_error(ER_WRONG_USAGE, MYF(0), "UNION", "INTO");
+    return TRUE;
+  }
+  if (lex->current_select->linkage == GLOBAL_OPTIONS_TYPE)
+  {
+    my_parse_error(ER(ER_SYNTAX_ERROR));
+    return TRUE;
+  }
+  /* This counter shouldn't be incremented for UNION parts */
+  lex->nest_level--;
+  if (mysql_new_select(lex, 0))
+    return TRUE;
+  mysql_init_select(lex);
+  lex->current_select->linkage=UNION_TYPE;
+  if (is_union_distinct) /* UNION DISTINCT - remember position */
+    lex->current_select->master_unit()->union_distinct=
+      lex->current_select;
+  return FALSE;
+}
+
+/**
+   @brief Initializes a SELECT_LEX for a query within parentheses (aka
+   braces).
+
+   @return false if successful, true if an error was reported. In the latter
+   case parsing should stop.
+ */
+bool setup_select_in_parentheses(LEX *lex) 
+{
+  SELECT_LEX * sel= lex->current_select;
+  if (sel->set_braces(1))
+  {
+    my_parse_error(ER(ER_SYNTAX_ERROR));
+    return TRUE;
+  }
+  if (sel->linkage == UNION_TYPE &&
+      !sel->master_unit()->first_select()->braces &&
+      sel->master_unit()->first_select()->linkage ==
+      UNION_TYPE)
+  {
+    my_parse_error(ER(ER_SYNTAX_ERROR));
+    return TRUE;
+  }
+  if (sel->linkage == UNION_TYPE &&
+      sel->olap != UNSPECIFIED_OLAP_TYPE &&
+      sel->master_unit()->fake_select_lex)
+  {
+    my_error(ER_WRONG_USAGE, MYF(0), "CUBE/ROLLUP", "ORDER BY");
+    return TRUE;
+  }
+  /* select in braces, can't contain global parameters */
+  if (sel->master_unit()->fake_select_lex)
+    sel->master_unit()->global_parameters=
+      sel->master_unit()->fake_select_lex;
+  return FALSE;
+}
+
 %}
 %union {
   int  num;
@@ -521,10 +605,10 @@ bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
 
 %pure_parser                                    /* We have threads */
 /*
-  Currently there are 168 shift/reduce conflicts.
+  Currently there are 174 shift/reduce conflicts.
   We should not introduce new conflicts any more.
 */
-%expect 168
+%expect 174
 
 /*
    Comments for TOKENS.
@@ -1240,6 +1324,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
         join_table_list  join_table
         table_factor table_ref esc_table_ref
         select_derived derived_table_list
+        select_derived_union
 
 %type <date_time_type> date_time_type;
 %type <interval> interval
@@ -1275,8 +1360,9 @@ bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
 
 %type <variable> internal_variable_name
 
-%type <select_lex> subselect take_first_select
-        get_select_lex
+%type <select_lex> subselect
+        get_select_lex query_specification 
+        query_expression_body
 
 %type <boolfunc2creator> comp_op
 
@@ -6757,37 +6843,22 @@ select_init:
 select_paren:
           SELECT_SYM select_part2
           {
-            LEX *lex= Lex;
-            SELECT_LEX * sel= lex->current_select;
-            if (sel->set_braces(1))
-            {
-              my_parse_error(ER(ER_SYNTAX_ERROR));
+            if (setup_select_in_parentheses(Lex))
               MYSQL_YYABORT;
-            }
-            if (sel->linkage == UNION_TYPE &&
-                !sel->master_unit()->first_select()->braces &&
-                sel->master_unit()->first_select()->linkage ==
-                UNION_TYPE)
-            {
-              my_parse_error(ER(ER_SYNTAX_ERROR));
-              MYSQL_YYABORT;
-            }
-            if (sel->linkage == UNION_TYPE &&
-                sel->olap != UNSPECIFIED_OLAP_TYPE &&
-                sel->master_unit()->fake_select_lex)
-            {
-               my_error(ER_WRONG_USAGE, MYF(0),
-                        "CUBE/ROLLUP", "ORDER BY");
-               MYSQL_YYABORT;
-            }
-            /* select in braces, can't contain global parameters */
-            if (sel->master_unit()->fake_select_lex)
-              sel->master_unit()->global_parameters=
-                 sel->master_unit()->fake_select_lex;
           }
         | '(' select_paren ')'
         ;
 
+/* The equivalent of select_paren for nested queries. */
+select_paren_derived:
+          SELECT_SYM select_part2_derived
+          {
+            if (setup_select_in_parentheses(Lex))
+              MYSQL_YYABORT;
+          }
+        | '(' select_paren_derived ')'
+        ;
+
 select_init2:
           select_part2
           {
@@ -8626,6 +8697,7 @@ when_list:
           }
         ;
 
+/* Equivalent to <table reference> in the SQL:2003 standard. */
 /* Warning - may return NULL in case of incomplete SELECT */
 table_ref:
           table_factor { $$=$1; }
@@ -8653,6 +8725,7 @@ esc_table_ref:
       | '{' ident table_ref '}' { $$=$3; }
       ;
 
+/* Equivalent to <table reference list> in the SQL:2003 standard. */
 /* Warning - may return NULL in case of incomplete SELECT */
 derived_table_list:
           esc_table_ref { $$=$1; }
@@ -8806,6 +8879,13 @@ normal_join:
         | CROSS JOIN_SYM {}
         ;
 
+/* 
+   This is a flattening of the rules <table factor> and <table primary>
+   in the SQL:2003 standard, since we don't have <sample clause>
+
+   I.e.
+   <table factor> ::= <table primary> [ <sample clause> ]
+*/   
 /* Warning - may return NULL in case of incomplete SELECT */
 table_factor:
           {
@@ -8843,12 +8923,29 @@ table_factor:
             /* incomplete derived tables return NULL, we must be
                nested in select_derived rule to be here. */
           }
-        | '(' get_select_lex select_derived union_opt ')' opt_table_alias
+          /*
+            Represents a flattening of the following rules from the SQL:2003
+            standard. This sub-rule corresponds to the sub-rule
+            <table primary> ::= ... | <derived table> [ AS ] <correlation name>
+            
+            The following rules have been flattened into query_expression_body
+            (since we have no <with clause>).
+
+            <derived table> ::= <table subquery>
+            <table subquery> ::= <subquery>
+            <subquery> ::= <left paren> <query expression> <right paren>
+            <query expression> ::= [ <with clause> ] <query expression body>
+
+            For the time being we use the non-standard rule
+            select_derived_union which is a compromise between the standard
+            and our parser. Possibly this rule could be replaced by our
+            query_expression_body.
+          */
+        | '(' get_select_lex select_derived_union ')' opt_table_alias
           {
             /* Use $2 instead of Lex->current_select as derived table will
                alter value of Lex->current_select. */
-
-            if (!($3 || $6) && $2->embedding &&
+            if (!($3 || $5) && $2->embedding &&
                 !$2->embedding->nested_join->join_list.elements)
             {
               /* we have a derived table ($3 == NULL) but no alias,
@@ -8870,7 +8967,7 @@ table_factor:
               if (ti == NULL)
                 MYSQL_YYABORT;
               if (!($$= sel->add_table_to_list(lex->thd,
-                                               ti, $6, 0,
+                                               new Table_ident(unit), $5, 0,
                                                TL_READ)))
 
                 MYSQL_YYABORT;
@@ -8878,7 +8975,8 @@ table_factor:
               lex->pop_context();
               lex->nest_level--;
             }
-            else if ($4 || $6)
+            else if ($3->select_lex &&
+                     $3->select_lex->master_unit()->is_union() || $5)
             {
               /* simple nested joins cannot have aliases or unions */
               my_parse_error(ER(ER_SYNTAX_ERROR));
@@ -8893,6 +8991,62 @@ table_factor:
           }
         ;
 
+select_derived_union:
+          select_derived opt_order_clause opt_limit_clause
+        | select_derived_union
+          UNION_SYM
+          union_option
+          {
+            if (add_select_to_union_list(Lex, (bool)$3, FALSE))
+              MYSQL_YYABORT;
+          }
+          query_specification
+          {
+            /*
+              Remove from the name resolution context stack the context of the
+              last select in the union.
+             */
+            Lex->pop_context();
+          }
+          opt_order_clause opt_limit_clause
+        ;
+
+/* The equivalent of select_init2 for nested queries. */
+select_init2_derived:
+          select_part2_derived
+          {
+            LEX *lex= Lex;
+            SELECT_LEX * sel= lex->current_select;
+            if (lex->current_select->set_braces(0))
+            {
+              my_parse_error(ER(ER_SYNTAX_ERROR));
+              MYSQL_YYABORT;
+            }
+            if (sel->linkage == UNION_TYPE &&
+                sel->master_unit()->first_select()->braces)
+            {
+              my_parse_error(ER(ER_SYNTAX_ERROR));
+              MYSQL_YYABORT;
+            }
+          }
+        ;
+
+/* The equivalent of select_part2 for nested queries. */
+select_part2_derived:
+          {
+            LEX *lex= Lex;
+            SELECT_LEX *sel= lex->current_select;
+            if (sel->linkage != UNION_TYPE)
+              mysql_init_select(lex);
+            lex->current_select->parsing_place= SELECT_LIST;
+          }
+          select_options select_item_list
+          {
+            Select->parsing_place= NO_MATTER;
+          }
+          opt_select_from select_lock_type
+        ;
+
 /* handle contents of parentheses in join expression */
 select_derived:
           get_select_lex
@@ -9508,8 +9662,7 @@ procedure_item:
 select_var_list_init:
           {
             LEX *lex=Lex;
-            if (!lex->describe && 
-                  (!(lex->result= new select_dumpvar(lex->nest_level))))
+            if (!lex->describe && (!(lex->result= new select_dumpvar())))
               MYSQL_YYABORT;
           }
           select_var_list
@@ -9590,7 +9743,7 @@ into_destination:
             LEX *lex= Lex;
             lex->uncacheable(UNCACHEABLE_SIDEEFFECT);
             if (!(lex->exchange= new sql_exchange($2.str, 0)) ||
-                !(lex->result= new select_export(lex->exchange, lex->nest_level)))
+                !(lex->result= new select_export(lex->exchange)))
               MYSQL_YYABORT;
           }
           opt_load_data_charset
@@ -9604,7 +9757,7 @@ into_destination:
               lex->uncacheable(UNCACHEABLE_SIDEEFFECT);
               if (!(lex->exchange= new sql_exchange($2.str,1)))
                 MYSQL_YYABORT;
-              if (!(lex->result= new select_dump(lex->exchange, lex->nest_level)))
+              if (!(lex->result= new select_dump(lex->exchange)))
                 MYSQL_YYABORT;
             }
           }
@@ -13223,33 +13376,8 @@ union_clause:
 union_list:
           UNION_SYM union_option
           {
-            LEX *lex=Lex;
-            if (lex->result && 
-               (lex->result->get_nest_level() == -1 ||
-                lex->result->get_nest_level() == lex->nest_level))
-              {
-                /* 
-                   Only the last SELECT can have INTO unless the INTO and UNION
-                   are at different nest levels. In version 5.1 and above, INTO
-                   will onle be allowed at top level.
-                */
-                my_error(ER_WRONG_USAGE, MYF(0), "UNION", "INTO");
-                MYSQL_YYABORT;
-              }
-            if (lex->current_select->linkage == GLOBAL_OPTIONS_TYPE)
-            {
-              my_parse_error(ER(ER_SYNTAX_ERROR));
-              MYSQL_YYABORT;
-            }
-            /* This counter shouldn't be incremented for UNION parts */
-            Lex->nest_level--;
-            if (mysql_new_select(lex, 0))
+            if (add_select_to_union_list(Lex, (bool)$2, TRUE))
               MYSQL_YYABORT;
-            mysql_init_select(lex);
-            lex->current_select->linkage=UNION_TYPE;
-            if ($2) /* UNION DISTINCT - remember position */
-              lex->current_select->master_unit()->union_distinct=
-                lex->current_select;
           }
           select_init
           {
@@ -13302,22 +13430,39 @@ union_option:
         | ALL       { $$=0; }
         ;
 
-take_first_select: /* empty */
-        {
-          $$= Lex->current_select->master_unit()->first_select();
-        };
+query_specification:
+          SELECT_SYM select_init2_derived
+          { 
+            $$= Lex->current_select->master_unit()->first_select();
+          }
+        | '(' select_paren_derived ')'
+          {
+            $$= Lex->current_select->master_unit()->first_select();
+          }
+        ;
 
+query_expression_body:
+          query_specification
+        | query_expression_body
+          UNION_SYM union_option 
+          {
+            if (add_select_to_union_list(Lex, (bool)$3, FALSE))
+              MYSQL_YYABORT;
+          }
+          query_specification
+          {
+            Lex->pop_context();
+            $$= $1;
+          }
+        ;
+
+/* Corresponds to <query expression> in the SQL:2003 standard. */
 subselect:
-        SELECT_SYM subselect_start select_init2 take_first_select 
-        subselect_end
-        {
-          $$= $4;
-        }
-        | '(' subselect_start select_paren take_first_select 
-        subselect_end ')'
-        {
-          $$= $4;
-        };
+          subselect_start query_expression_body subselect_end
+          { 
+            $$= $2;
+          }
+        ;
 
 subselect_start:
           {