Bug #32858: Erro: "Incorrect usage of UNION and INTO" does not take

subselects into account

It is forbidden to use the SELECT INTO construction inside UNION statements
unless on the last SELECT of the union. The parser records whether it 
has seen INTO or not when parsing a UNION statement. But if the INTO was
legally used in an outer query, an error is thrown if UNION is seen in a
subquery. Fixed in 5.0 by remembering the nesting level of INTO tokens and 
mitigate the error unless it collides with the UNION.


mysql-test/r/union.result:
  Bug#32858: Test result
mysql-test/t/union.test:
  Bug#32858: Test case
sql/sql_class.cc:
  Bug#32858: Initializing new member
sql/sql_class.h:
  Bug#32858: Added property nest_level to select_result class.
sql/sql_yacc.yy:
  Bug#32858: The fix.

3 files changed, 51 insertions, 12 deletions

diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index b67f63778dc..87553837641 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -931,6 +931,7 @@ 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 e6d65f3133a..80665f8b4dc 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -1891,6 +1891,7 @@ class select_result :public Sql_alloc {
 protected:
   THD *thd;
   SELECT_LEX_UNIT *unit;
+  uint nest_level;
 public:
   select_result();
   virtual ~select_result() {};
@@ -1927,6 +1928,12 @@ 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
@@ -2006,7 +2013,14 @@ class select_export :public select_to_file {
   bool is_unsafe_field_sep;
   bool fixed_row_size;
 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);
@@ -2015,7 +2029,15 @@ 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);
 };
@@ -2422,7 +2444,16 @@ class select_dumpvar :public select_result_interceptor {
   ha_rows row_count;
 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 82100b3d3dd..0c2c8c2bc8e 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -6356,7 +6356,8 @@ procedure_item:
 select_var_list_init:
 	   {
              LEX *lex=Lex;
-	     if (!lex->describe && (!(lex->result= new select_dumpvar())))
+	     if (!lex->describe && 
+                 (!(lex->result= new select_dumpvar(lex->nest_level))))
 	        MYSQL_YYABORT;
 	   }
 	   select_var_list
@@ -6430,7 +6431,7 @@ 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->result= new select_export(lex->exchange, lex->nest_level)))
             MYSQL_YYABORT;
 	}
 	opt_field_term opt_line_term
@@ -6442,7 +6443,7 @@ 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)))
+	    if (!(lex->result= new select_dump(lex->exchange, lex->nest_level)))
 	      MYSQL_YYABORT;
 	  }
 	}
@@ -9421,12 +9422,18 @@ union_list:
 	UNION_SYM union_option
 	{
 	  LEX *lex=Lex;
-	  if (lex->result)
-	  {
-	    /* Only the last SELECT can have  INTO...... */
-	    my_error(ER_WRONG_USAGE, MYF(0), "UNION", "INTO");
-	    MYSQL_YYABORT;
-	  }
+	  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));