MDEV-8909 union parser cleanup

This is the final patch removing some old remainders that are
not needed anymore.

(Other clean-ups were done in earlier commits)

sql/sql_lex.cc

@@ -2457,7 +2457,6 @@ bool st_select_lex::mark_as_dependent(THD *thd, st_select_lex *last,
   return FALSE;
 }
 
-bool st_select_lex_node::set_braces(bool value)      { return 1; }
 bool st_select_lex_node::inc_in_sum_expr()           { return 1; }
 uint st_select_lex_node::get_in_sum_expr()           { return 0; }
 TABLE_LIST* st_select_lex_node::get_table_list()     { return 0; }
@@ -2607,13 +2606,6 @@ st_select_lex* st_select_lex::outer_select()
 }
 
 
-bool st_select_lex::set_braces(bool value)
-{
-  braces= value;
-  return 0; 
-}
-
-
 bool st_select_lex::inc_in_sum_expr()
 {
   in_sum_expr++;

sql/sql_lex.h

@@ -531,7 +531,6 @@ class st_select_lex_node {
   virtual st_select_lex* outer_select()= 0;
   virtual st_select_lex* return_after_parsing()= 0;
 
-  virtual bool set_braces(bool value);
   virtual bool inc_in_sum_expr();
   virtual uint get_in_sum_expr();
   virtual TABLE_LIST* get_table_list();
@@ -955,7 +954,10 @@ class st_select_lex: public st_select_lex_node
 
   bool mark_as_dependent(THD *thd, st_select_lex *last, Item *dependency);
 
-  bool set_braces(bool value);
+  void set_braces(bool value)
+  {
+    braces= value;
+  }
   bool inc_in_sum_expr();
   uint get_in_sum_expr();
 

sql/sql_parse.cc

@@ -7468,22 +7468,16 @@ mysql_new_select(LEX *lex, bool move_down)
       my_error(ER_WRONG_USAGE, MYF(0), "UNION", "INTO");
       DBUG_RETURN(TRUE);
     }
-    if (lex->proc_list.elements!=0)
-    {
-      my_error(ER_WRONG_USAGE, MYF(0), "UNION",
-               "SELECT ... PROCEDURE ANALYSE()");
-      DBUG_RETURN(TRUE);
-    }
-    if (lex->current_select->order_list.first && !lex->current_select->braces)
-    {
-      my_error(ER_WRONG_USAGE, MYF(0), "UNION", "ORDER BY");
-      DBUG_RETURN(1);
-    }
-    if (lex->current_select->explicit_limit && !lex->current_select->braces)
-    {
-      my_error(ER_WRONG_USAGE, MYF(0), "UNION", "LIMIT");
-      DBUG_RETURN(1);
-    }
+
+    // SELECT 1 FROM t1 PROCEDURE ANALYSE() UNION ...  --    not possible
+    DBUG_ASSERT(lex->proc_list.elements == 0);
+    // SELECT 1 FROM t1 ORDER BY 1 UNION SELECT 1 FROM t1 -- not possible
+    DBUG_ASSERT(!lex->current_select->order_list.first ||
+                lex->current_select->braces);
+    // SELECT 1 FROM t1 LIMIT 1 UNION SELECT 1 FROM t1;   -- not possible
+    DBUG_ASSERT(!lex->current_select->explicit_limit ||
+                lex->current_select->braces);
+
     select_lex->include_neighbour(lex->current_select);
     SELECT_LEX_UNIT *unit= select_lex->master_unit();                              
     if (!unit->fake_select_lex && unit->add_fake_select_lex(lex->thd))

sql/sql_yacc.yy

@@ -714,34 +714,6 @@ bool add_select_to_union_list(LEX *lex, bool is_union_distinct,
   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(lex->thd, ER_SYNTAX_ERROR);
-    return TRUE;
-  }
-  */
-  DBUG_ASSERT(sel->braces);
-  if (sel->linkage == UNION_TYPE &&
-      !sel->master_unit()->first_select()->braces &&
-      sel->master_unit()->first_select()->linkage ==
-      UNION_TYPE)
-  {
-    my_parse_error(lex->thd, ER_SYNTAX_ERROR);
-    return TRUE;
-  }
-  return FALSE;
-}
 
 static bool add_create_index_prepare(LEX *lex, Table_ident *table)
 {
@@ -8398,8 +8370,7 @@ select_paren:
           SELECT_SYM select_options_and_item_list select_part3
           opt_select_lock_type
           {
-            if (setup_select_in_parentheses(Lex))
-              MYSQL_YYABORT;
+            DBUG_ASSERT(Lex->current_select->braces);
           }
         | '(' select_paren ')'
         ;
@@ -8415,8 +8386,7 @@ select_paren_union_query_term:
           SELECT_SYM select_options_and_item_list select_part3_union_query_term
           opt_select_lock_type
           {
-            if (setup_select_in_parentheses(Lex))
-              MYSQL_YYABORT;
+            DBUG_ASSERT(Lex->current_select->braces);
           }
         | '(' select_paren_union_query_term ')'
         ;
@@ -8432,8 +8402,7 @@ select_paren_view:
           SELECT_SYM select_options_and_item_list select_part3_view
           opt_select_lock_type
           {
-            if (setup_select_in_parentheses(Lex))
-              MYSQL_YYABORT;
+            DBUG_ASSERT(Lex->current_select->braces);
           }
         | '(' select_paren_view ')'
         ;
@@ -8449,8 +8418,7 @@ select_paren_derived:
           opt_limit_clause
           opt_select_lock_type
           {
-            if (setup_select_in_parentheses(Lex))
-              MYSQL_YYABORT;
+            DBUG_ASSERT(Lex->current_select->braces);
             $$= Lex->current_select->master_unit()->first_select();
           }
         | '(' select_paren_derived ')'  { $$= $2; }
@@ -11076,12 +11044,7 @@ union_list_derived:
 select_init2_derived:
           select_part2_derived
           {
-            LEX *lex= Lex;
-            if (lex->current_select->set_braces(0))
-            {
-              my_parse_error(thd, ER_SYNTAX_ERROR);
-              MYSQL_YYABORT;
-            }
+            Select->set_braces(0);
           }
         ;
 
@@ -11126,16 +11089,8 @@ select_derived:
 derived_query_specification:
           SELECT_SYM select_derived_init select_derived2
           {
-            LEX *lex= Lex;
-            SELECT_LEX *sel= lex->current_select;
             if ($2)
-            {
-              if (sel->set_braces(1))
-              {
-                my_parse_error(thd, ER_SYNTAX_ERROR);
-                MYSQL_YYABORT;
-              }
-            }
+              Select->set_braces(1);
             $$= NULL;
           }
         ;