Produce an error when arguments are not compatible for CONCAT()

sql/item.cc

@@ -180,13 +180,10 @@ bool Item::set_charset(CHARSET_INFO *cs1, enum coercion co1,
     set_charset(&my_charset_bin, COER_NOCOLL);
     return 0;
   }
-  
+
   if (!my_charset_same(cs1,cs2))
-  {
-    set_charset(&my_charset_bin, COER_NOCOLL);
-    return 0;
-  }
-  
+    return 1;
+
   if (co1 < co2)
   {
     set_charset(cs1, co1);
@@ -198,7 +195,12 @@ bool Item::set_charset(CHARSET_INFO *cs1, enum coercion co1,
   else  // co2 == co1
   {
     if (cs1 != cs2)
-      set_charset(&my_charset_bin, COER_NOCOLL);
+    {
+      CHARSET_INFO *bin= get_charset_by_csname(cs1->csname, MY_CS_BINSORT,MYF(0));
+      if (!bin)
+	return 1;
+      set_charset(bin, COER_NOCOLL);
+    }
     else
       set_charset(cs2, co2);
   }

sql/item_strfunc.cc

@@ -328,8 +328,12 @@ void Item_func_concat::fix_length_and_dec()
   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 (set_charset(charset(), coercibility,
+		args[i]->charset(), args[i]->coercibility))
+    {
+      my_error(ER_WRONG_ARGUMENTS,MYF(0),func_name());
+      break;
+    }
   }
 
   if (max_length > MAX_BLOB_WIDTH)