Getting closer to be more SQL99 in dyadic operations

mysql-test/r/ctype_collate.result:
  NO COLLATION has less coercibility than IMPLICIT and COERCIBLE
sql/item.cc:
  Function to choose collation for dyadic operations
sql/item.h:
  NO COLLATION has less coercibility than IMPLICIT and COERCIBLE
sql/item_func.cc:
  Function to choose collation for dyadic operations
sql/item_strfunc.cc:
  Function to choose collation for dyadic operations
sql/item_strfunc.h:
  Use arg's attributes

mysql-test/r/ctype_collate.result

@@ -523,7 +523,7 @@ Variable_name	Value
 client_collation	latin1
 SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
 charset('a')	collation('a')	coercibility('a')	'a'='A'
-latin1	latin1	2	1
+latin1	latin1	3	1
 SET NAMES latin1 COLLATE latin1_bin;
 SHOW VARIABLES LIKE 'client_collation';
 Variable_name	Value
@@ -538,35 +538,35 @@ Variable_name	Value
 client_collation	latin1_bin
 SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
 charset('a')	collation('a')	coercibility('a')	'a'='A'
-latin1	latin1_bin	2	0
+latin1	latin1_bin	3	0
 SET NAMES koi8r;
 SHOW VARIABLES LIKE 'client_collation';
 Variable_name	Value
 client_collation	koi8r
 SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
 charset('a')	collation('a')	coercibility('a')	'a'='A'
-latin1	latin1	2	1
+latin1	latin1	3	1
 SET COLLATION koi8r_bin;
 SHOW VARIABLES LIKE 'client_collation';
 Variable_name	Value
 client_collation	koi8r_bin
 SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
 charset('a')	collation('a')	coercibility('a')	'a'='A'
-latin1	latin1	2	1
+latin1	latin1	3	1
 SET COLLATION DEFAULT;
 SHOW VARIABLES LIKE 'client_collation';
 Variable_name	Value
 client_collation	koi8r
 SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
 charset('a')	collation('a')	coercibility('a')	'a'='A'
-latin1	latin1	2	1
+latin1	latin1	3	1
 SET NAMES DEFAULT;
 SHOW VARIABLES LIKE 'client_collation';
 Variable_name	Value
 client_collation	latin1
 SELECT charset('a'),collation('a'),coercibility('a'),'a'='A';
 charset('a')	collation('a')	coercibility('a')	'a'='A'
-latin1	latin1	2	1
+latin1	latin1	3	1
 SET NAMES latin1 COLLATE koi8r;
 COLLATION 'koi8r' is not valid for CHARACTER SET 'latin1'
 SET NAMES 'DEFAULT';

sql/item.cc

@@ -172,6 +172,39 @@ CHARSET_INFO * Item::default_charset() const
   return current_thd->db_charset;
 }
 
+bool Item::set_charset(CHARSET_INFO *cs1, enum coercion co1,
+		       CHARSET_INFO *cs2, enum coercion co2)
+{
+  if (cs1 == &my_charset_bin || cs2 == &my_charset_bin)
+  {
+    set_charset(&my_charset_bin, COER_NOCOLL);
+    return 0;
+  }
+  
+  if (!my_charset_same(cs1,cs2))
+  {
+    set_charset(&my_charset_bin, COER_NOCOLL);
+    return 0;
+  }
+  
+  if (co1 < co2)
+  {
+    set_charset(cs1, co1);
+  }
+  else if (co2 < co1)
+  {
+    set_charset(cs2, co2);
+  }
+  else  // co2 == co1
+  {
+    if (cs1 != cs2)
+      set_charset(&my_charset_bin, COER_NOCOLL);
+    else
+      set_charset(cs2, co2);
+  }
+  return 0;
+}
+
 Item_field::Item_field(Field *f) :Item_ident(NullS,f->table_name,f->field_name)
 {
   set_field(f);
@@ -195,8 +228,7 @@ void Item_field::set_field(Field *field_par)
   table_name=field_par->table_name;
   field_name=field_par->field_name;
   unsigned_flag=test(field_par->flags & UNSIGNED_FLAG);
-  set_charset(field_par->charset());
-  coercibility= COER_IMPLICIT;
+  set_charset(field_par->charset(), COER_IMPLICIT);
 }
 
 const char *Item_ident::full_name() const

sql/item.h

@@ -39,8 +39,8 @@ public:
              SUBSELECT_ITEM, ROW_ITEM, CACHE_ITEM};
 
   enum cond_result { COND_UNDEF,COND_OK,COND_TRUE,COND_FALSE };
-  enum coercion    { COER_NOCOLL=3,   COER_COERCIBLE=2, 
-  		     COER_IMPLICIT=1, COER_EXPLICIT=0  };
+  enum coercion    { COER_COERCIBLE=3, COER_IMPLICIT=2, 
+  		     COER_NOCOLL=1,    COER_EXPLICIT=0  };
 
   String str_value;			/* used to store value */
   my_string name;			/* Name from select */
@@ -113,6 +113,13 @@ public:
   CHARSET_INFO *default_charset() const;
   CHARSET_INFO *charset() const { return str_value.charset(); };
   void set_charset(CHARSET_INFO *cs) { str_value.set_charset(cs); }
+  void set_charset(CHARSET_INFO *cs, enum coercion coer)
+  {
+    str_value.set_charset(cs);
+    coercibility= coer;
+  }
+  bool set_charset(CHARSET_INFO *cs1, enum coercion co1, 
+  		   CHARSET_INFO *cs2, enum coercion co2);
   virtual void set_outer_resolving() {}
 
   // Row emulation

sql/item_func.cc

@@ -107,7 +107,6 @@ Item_func::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
     return 0;					// Fatal error if flag is set!
   if (arg_count)
   {						// Print purify happy
-    bool first_coll= 1;
     for (arg=args, arg_end=args+arg_count; arg != arg_end ; arg++)
     {
       if ((*arg)->fix_fields(thd, tables, arg) ||
@@ -116,38 +115,6 @@ Item_func::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
       if ((*arg)->maybe_null)
 	maybe_null=1;
       
-      if ((*arg)->result_type() == STRING_RESULT)
-      {
-	/*
-	  Set return character set to first argument if we are returning a
-	  string.
-	*/
-	if (first_coll)
-	{
-	  set_charset((*arg)->charset());
-	  coercibility= (*args)->coercibility;
-	  first_coll= 0;
-	}
-	else if ((*arg)->charset() == &my_charset_bin || 
-		 charset() == &my_charset_bin)
-	{
-	  set_charset(&my_charset_bin);
-	  coercibility= COER_NOCOLL;
-	}
-	else if ((*arg)->coercibility < coercibility)
-	{
-	  if (!my_charset_same(charset(),(*arg)->charset()))
-	  {
-	    set_charset(&my_charset_bin);
-	    coercibility= COER_NOCOLL;
-	  }
-	  else
-	  {
-	    coercibility= (*arg)->coercibility;
-	    set_charset((*arg)->charset());
-	  }
-	}
-      }
       with_sum_func= with_sum_func || (*arg)->with_sum_func;
       used_tables_cache|=(*arg)->used_tables();
       const_item_cache&= (*arg)->const_item();

sql/item_strfunc.cc

@@ -321,9 +321,17 @@ null:
 
 void Item_func_concat::fix_length_and_dec()
 {
+  bool first_coll= 1;
   max_length=0;
+
+  set_charset(args[0]->charset(),args[0]->coercibility);
   for (uint i=0 ; i < arg_count ; i++)
+  {
     max_length+=args[i]->max_length;
+    set_charset(charset(), coercibility,
+		args[i]->charset(), args[i]->coercibility);
+  }
+
   if (max_length > MAX_BLOB_WIDTH)
   {
     max_length=MAX_BLOB_WIDTH;
@@ -978,6 +986,7 @@ void Item_func_substr::fix_length_and_dec()
 {
   max_length=args[0]->max_length;
 
+  set_charset(args[0]->charset(), args[0]->coercibility);
   if (args[1]->const_item())
   {
     int32 start=(int32) args[1]->val_int()-1;
@@ -1791,6 +1800,7 @@ inline String* alloc_buffer(String *res,String *str,String *tmp_value,
 
 void Item_func_repeat::fix_length_and_dec()
 {
+  set_charset(args[0]->charset(), args[0]->coercibility);
   if (args[1]->const_item())
   {
     max_length=(long) (args[0]->max_length * args[1]->val_int());
@@ -2028,8 +2038,7 @@ String *Item_func_conv_charset::val_str(String *str)
 void Item_func_conv_charset::fix_length_and_dec()
 {
   max_length = args[0]->max_length*conv_charset->mbmaxlen;
-  coercibility= COER_IMPLICIT;
-  set_charset(conv_charset);
+  set_charset(conv_charset, COER_IMPLICIT);
 }
 
 
@@ -2171,9 +2180,7 @@ bool Item_func_set_collation::fix_fields(THD *thd,struct st_table_list *tables,
       set_collation->name,args[0]->charset()->csname);
     return 1;
   }
-  set_charset(set_collation);
-  
-  coercibility= COER_EXPLICIT;
+  set_charset(set_collation, COER_EXPLICIT);
   with_sum_func= with_sum_func || args[0]->with_sum_func;
   used_tables_cache=args[0]->used_tables();
   const_item_cache=args[0]->const_item();

sql/item_strfunc.h

@@ -151,7 +151,11 @@ class Item_str_conv :public Item_str_func
 {
 public:
   Item_str_conv(Item *item) :Item_str_func(item) {}
-  void fix_length_and_dec() { max_length = args[0]->max_length; }
+  void fix_length_and_dec()
+  { 
+    set_charset(args[0]->charset(), args[0]->coercibility);
+    max_length = args[0]->max_length;
+  }
 };