Re:strange execution error

Re:strange execution error

[Zheng Long Gen]

>After compiling with GNAT I execute it and it gets completely frozen, 
>the most curious about it is that 4 processes are created. Gdb tells me 
>the error comes from messages.adb line 152:
>
>
>  Append(Source   => Str,
>         New_Item => Interrupt_ID'Pos(Msg.Value.Which));

acturally the problem  is caused by the first call to set_string in 
messages.adb 
   Set_String (UP => Str, S  => MFR_Arr(Msg.Cons);

this procedure set the contents of str an  access value which points to a 
library level aliased constant string. The procedure Append, however, will 
free the memory of this constant string after allocate new space of memory.
Work around:
procedure To_unbounded_string will be more safer :
    str:=to_unbounded_string(MFR_Arr(Msg.Cons).all);
By the way, the second local procedure append (...) which appends  a float to 
the unbounded string is also terrible:
        ............
         P : String_Access := null;
      begin
         Put(P.all, New_Item);
I don't think a string_access object pointing to null can hold anything 
legally.

    Hope this will help

    zhenggen
    20030223